The NC-4 transatlantic flight seaplane aloft, as seen from one of her companion flying boats The Vickers " Vimy " bomber leaving St. John's for the non-stop transatlantic flight .TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING HY HENRY WOODHOUSE u IHOR OF "TEXTBOOK or KAVAI AEBONAI n. ." "IIXTBOOK or MILITARY AERONAUTICS," "AIRO BIXE BOOK." MEMBER or TIM: BOARD of UOVKRNORR or AKRO nr or AMERICA. vici-l-Rrsn.. v t AKRIAl I I V..' r. Or AMERICA, MEMBER OF NATIONAL AERIAL COAST FATROL COM- MI-.IMS. III. Mil VM..IIVI..MVX ol COMMITTEE OK AERONAl'TK NATIONAL iv-HTITr OF Fill. II- Y. MEMBER OF THE gOCIKTY Ot AVTOMOTITE ri -|UM VM> INDI-ITBIAI. DEI.EOATE PAN-AMERICAN FEDERATION. ETC., ETC., ETC. NEW YORK THE CENTURY CO. 1920 3 Copyright, 1920, by THE CENTUBY Co. Published, January, 1920 Textbook of Applied Aeronautic Engineering INTRODUCTION Thi- ni-nunm-nt.-il work on aeronautic -n-in, -. mi- i- ,-inl importance .-ind value .-it this time In cause it tells in a simple laminate, anil without difficult formulas. Imu l.-iri." icroplancs ..in ! Imilt for arrial transporta- .TII!. by i:ivini: tin drawings, ili aurains and photo- graph- iif existing ami (iroposrcl types of aeroplane- .iii,l i . iltli nt engineering data, will ,-issist engineers in hiiildint: aeroplane- large and small, for .-irri.-il transporta- ul other purposes. While travelliii!: tlirouiili South and Central Am- ri.- i \ I was n-mimli-d daily that South and Central rii-a in waiting fr aerial transportation. In tin i eoiintrii-s we have many ditlieult prolili-nis of traiisportati..ii whieh eati lie easily solved liy aircraft. L'pon the solution of this, prohlems depends the cco- noniie wcifa'rc and eiiiiim-rei.il developmi-nt of these roun- trie-. lii re mountains, forests and waterways make the of building railroads prohihitiv- The stupendous flights of the X. ('. I. the Vickers "Vimy and other large aeroplanes have aroused hopes that i. rial transportation lines will be established in the future. In everv o n. of tin Latin Amerieaii countries there arc people with imagination and capital who would like to tak. steps to establish air lines, but they do not quite know how to go about it. Soon, we hope, enterprising experts in the I 'nit-d States will come to our assistance and establish these lines. While tin- I'an American aeronautic movement is youth- ful, having IM-I-II conceived by Mr. Henry WoodhoUM in I'll I. and -volvcd l>y him and the other energetic and in- men. who are responsible for so many im- portant aeronautic movements Messrs. Alan R. Hawley. H. ar Vdmiral Hob, rt K. Peary, John Barrett, and Henry A. \\ i- Wind it is advancing in gigantic strides. ins, of the broad expanse of territory, the lack of roads into all sections of the country, the excellent ways, all kinds of aircraft will be of great value to tin I'nitcd States and Canada, as well as to South and r.d America. I u. years ago I went with Mr. Woodhouse to visit tin ( urtiss Aeroplane factory at Buffalo. The pur|M>sc of our visit was to prove to ourselves that an aeroplane .etually being built that could lift a ton. Reports had bei n circulated that such an aeroplane was being designed, but the thing was not considered possible or practical. Mr. Woodhouse and mvs.l! had IM-I-II study- ing the need of aerial transportation in South ami < n tral Am. ne.i and w. rcali/.rd that, if it was true that such an aeroplane was Ix-ing built, there were prospects for the establishing of aerial transportation lines in South and Central America within a few years, which would solve the difficult problems of transportation. We went to HuH'alo with keen , \peetation. but did not expect to actually see a large aeroplane under construction, be- cause at the time even the highest engineers did not admit the possibility of building large aeroplanes that would fly successfully. They generally held that a, n. planes with two motors were impractical, because in the event of one motor stopping, the aeroplane, according to their computations, would spin around and it would be impossible for the pilot to control it. They also held that propellers would not stand the vibrations of high horse power engines. To our great satisfaction and wonderment we found in the Curtiss factory a huge seaplane almost completed which, we know now. was a prototype of the N. C I. which Hew across the Atlantic. I clearly recall how very few people believed an when we reported to them what we had seen. It seemed impossible ! In this valuable Textbook. Mr. \Voodhousc points out the possibility of building aeroplanes to lift twenty tons of useful load, and he explain* hou- H can be done! It is not prophecy on his part; it is knowledge of the broadest aspects of aeronautic engineering and of the aeronautic art as a whole, with the development of which he has Ix-cn closely identified for the past ten years. Furthermore. Mr. Womlhouse urges original experi- ments in the distribution of the 10,000 square feet of wing space which is required to lift twenty tons of us, ful load. He presents the problems to be solved in clear, simple language and clearly defines the factors which will make for success in developing large machines for aerial trans- portation. Then-fore, this Textbook will be of great assistance to aeronautic engineers and to every IMTSOII who is interested in the development of aerial trans- portation and the use of aeroplanes for general pur P ALBERTO SANTOS-DI-MONT, Honorary Prrtiilrnl l'a-.-lmrrira .Irronaulir pntrratiii*. r, .; CONTENTS PAGE CHAPTER I STATI-S OF APPLIED AERONAITI. Bva NKKUINIi 3 \\.ir Developed Speed Kcgardlcss of Klying Kfficicllt-y 3 ,t Bomliini: and Antiaircraft llrnii^ht . \lMint Vnl- lialilr DcM-lop Mil-lit-, ill AiTi>|.|.-inr Construction . 5 K.ngiiiecrintr \il\antiijrcs in I Urge M i. hines ... o Phwoixl Coiistrm -lion Our t Most Important l>,\.| incuts T\p.sot II. .*icr Th.in \ir Aircraft 7 Status .if Present l>.-i> Aeroplanes . Detailed Views of NC-l Transatlantic T\ pc Seaplane 12 Cellini: tin- Sniiif KngiMccring liesiilts liy Diffi-rrnt Distriliiiti.uis of \Vin;r \re.i .... 14 Mow Can \Vr DistriUitc tli.- KMKI Square Feet of Wing Surface ltri|iiiri-.l to Lift -' Tons of L'se- ful l.oadr 1 \rca Distrih-ition. Win^s with \-pcct Uatin of 6 to 1 17 Kclation of Cap to Chord 17 Tandem Planes lti-pr.--.-nt tin- Solution I'rolilenis of Trussing HIM! Bracing B.xlv C. instruct ion 19 II Mi I.TI AEROPLANES 23 The .i-Motornl C.-riiian Biplane . Tlir l-Motornl Voisin Triplane ....... -'"' Hi,- t Moton-d llaiidlcy-Pagc Biplane ..... -'> III.- l-Mot.ir<-il Sikorsky Biplane ....... -' Hi, I M,.lor,-d Zeppelin Biplane . . x -Curtiss No I TnuiMitlantic- SfiijtUne 33 The Capraol Bombing TrtpUne Type CA-4 . ... 37 Curtiss II li- A l-'lyinu Boat ........ 41 I , I \ ivj I l\ini: Uoit . . . il.in.ll.-> Page Type O-MM Bomber ..... +7 Tlir Martin Cruisinjr Bomljer ........ *0 Cl.-iiii 1.. Martin Bomlx-r ......... ' Siiiulstitlt-lliinnrvi); Si-a]>lnnr ...... Bur^'--' Twin-.Motcin-il llydroai-roplani- ..... 59 Thr TransatlantU- 'I'vpr VirkiTs - \'iiny " .... 60 Uro Twin l-'.njrini-d Bonilx-r . . . Ijiwson Aerial Transport . The Krii-ilri.-li-.hafm Twin-Motoml Biplane ... 67 The Cotlia Twin-Motor.-d Biplane - Type (5O. G5 . The C.-rman A. K. C . ({.milling Biplane .... 79 Cnrtixs M.xlrl 1H-B Biplane ....... "0 The Cnrti-s "Oriole" Biplane ....... 81 C'n \PTER III SiNoi.K MOTORED AEROPLANES . . 82 The Ai-riniiiiriiK- Tniininp Tractor ...... The Hellnnea Biplane .......... * Cnrtiss M.Hlrl .IN-tl) Tra.-tor ........ 87 The IV Havillan.l t Trai-tor Biplane ...... * The I). II. '. I'ursiiit Biplanr ........ 93 The I).- llavillanil No. 5 ......... 94 I'hr T-l MesM-np-r ........... 96 The Berekman-. Speeil Si-out ........ The Christinas Stnitlrss Biplane ....... 101 The I,nws,m M. T. -' Traetor Biplane . . . Oallnudrt K.-l. .' Mononl.inr ... The C.allnnilet K.-l. .' " Chiiiiimy KlynlK.nt " Monoplane 1M The I.e Pere Kijihter .......... 1" Onlnanre Knaineerlne Srout SO Ix-Rhftne . The (). I. . C TM..-S B ami C Single Sealer . . . . 1O9 The Martin K-III Single Sealer ...... The Parltanl Aeroplane ..... 11* FAOE The Standard K-l Single Seater 117 The VK-7 TraininK Biplam- ll The Three-Motored White Monoplane 119 The Standard Mo.1,-1 I. I Mail Aeroplane . . . . 1-'" Thomas-Morse, T\| " l< s mv .|,- ^-ater Sront . . 1.'-' Thomas-Morse, T\ p. - II Sin^le-seiiter Scout . . 1-'-' Thomas-Morse, Type -S-ti Tandem Two-seater . . I-"-' Thomas-Morse, T>pe S 7 Side. I.) -Side To-seater . I .'. The Thomas-Morse Type M-B-H, :X) h.p. Ilispano Kncine KiRhter ." l-'l The Kren.h A. . Biplane IM The Bn-truet Biplane 1JH The Sopwith Maehine 130 The Short .Miii-hine ISO The Martinsyde Type l:JI Crahame-White \.-ro Limousine . 1:1-' The C.TIM:, ii Gothas. th. Aviatiks and the Ago Bi- planes l: The Nieiiport P. Planes 135 The S|>a.l Seoul. Type S VII I.! 1 ' Bristol Si-out so I.e l< hone 11:1 I S. B.-l British Kighter 1** 300 Hispiino-Siiizu {'. S. Army Tests 144 Martinsydr Seoul IWKI I lispaiio-Suizii 147 The Knglish S. K. :> Single-Seiiter Kighter .... 151 S. K. j IKO llis]).ino-Suixa 154 The British Sopwith Planes . . 15fi The Sopwith "Camel" 156 British Avro Aeroplanes 157 The S. V. A. Kiphtinp Seoul 159 The I'oinilio Heeonimissanee T\ pe Traetor .... 161 The A. K. C'i. Cerman Armored Biplane .... 163 The German Api Kighling Biplane 165 The Allmtros Type "I V " 1-Vt" I 70 The Kokker SinVlf Seater Biplane T> pe O-7 . . 186 Tlie Tarranl "TalMir" Triplane 191 The MallH-rstadl l-'ighter '"-' The Cerman llansH-Brandenhiirg Traetor .... 195 Details of Ihe Austrian Hansa-Brandeiihiirj: Traetor l'i; The Wittemann-I.rwis Commereial Biplane .... 198 The Holand Chaser I). II -'IX) The I.. V. C. Biplane Type C. V The Ae.-Mot.ired Single Seater Aee Biplane . . . iK)4 The Hannoveraner Biplane 207 IlallM-rstadt-Kil) Mem-des JOB The PfaU Biplane I). Ill -M" Pfalr. Seoul S.* I I7-1WI Mer.-edes JU Trails on Avialik No. G.IMJ. I . 214 Dimensions and Kquipmrnt of Ihe 1918-1919 Types of Cerman Aeroplanes -'I* The C. IV Kiimpler Biplane 216 The Curtiss Model IH-T Triplane .... The Sopwith Triplane . Perspective Sketches of the Cerman Kokker Triplane J.'t The Kokker Triplane The Aeromarine Training Seaplane The Aeromarine " T-.VI " Three Seater Flying Boat . Boeing Seaplane Type C-I-K ** The Burgess Speed Scout Seaplane The Curtiss II- \ Hydro 23M Curtiss M.Kl.-l IIS- .'-I. Klying Boat 235 Curtiss M.nlel MK Klying Boal . . The Gallaudet D- l.iirht Bomlx-r S-apliine Thomas-Morse T\ pe -S-.'. Single-seater Seaplane . . 241 V, v i M .' Bahy Seaplane The'K. B. A. Klying Boat .... 243 CONTEXTS Au*triiin Apo Flyinsr Boat 2*8 The Lohner Flying Boat 2*9 CHAPTER IV AEROPLANE AND SEAPLANE ENGI- NEERING 251 CHAPTER V NAVY DEPARTMENT AEROPLANE SPE- CIFICATIONS 263 CHAPTER VI METHOD OF SELECTION OF AN AERO- PLANE WING AS TO AREA AND SECTION . . . 271 CHAPTER VII NOMOGHAPHIC CHARTS FOR THE AERIAL PROPELLER 276 CHAPTER VIII METHODS USED IN FINDING FUSEL- AGE STRESSES 280 PAGE CHAPTER IX THEORY OF FLIGHT 28 1 CHAPTER X SHIPPING, UNLOADING AND ASSEMBLING 29-1 CHAPTER XI RIGGING 296 CHAPTER XII ALIGNMENT 303 CHAPTER XIII CARE AND INSPECTION .... 308 CHAPTER XIV MINOR REPAIRS 310 CHAPTER XV VALUE OF PLYWOOD IN AEROPLANE FUSELAGE CONSTRUCTION 312 Properties of Various Woods 315 CHAPTER XVI NOMENCLATURE FOR AERONAUTICS 316 The Metric System .324 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Hear view of the 1903 Wright 1 lyrr The first aeroplane to fly. CHAPTER I STATUS OF APPLIED AERONAUTIC ENGINEERING Aeronautic Kngineering as an applied art is only ;i few years old. From December 17. 1903. when the Wrights made their first flight, to 1916, tin- world's aero- nautic engineers were so few that they could be counted mi one's finger tips. In 1 !!_>. there were no schools of aeronautic cn-rim-cring and Mr. Henry A. Wise Wood, the editor ,,f "Flying Maga/ine," and the writer urged tlie leading Universities to establish a course ill aeronautic engineering. Only one University responded. The others stated that the need for such a course was not sufficiently evident to justify the step. In 1917-1918 courses in aeronautic engineer- ing were established at a mimlrcr of Universities, but the purpose was mainly to give cadets an elementary course on the theory of flight; to teach them the most elementary principles in the slim-test time possible. The text of the most complete course of its kind is reproduced in the Index, entitled "Theory of Flight." The greatest work in aeronautic engineering in the United States was done at the U. S. Army Aeroplane Engineering Department at Dayton in 1918-1919 and at the largest aero- plane factories. Their work was. however, lim- ited to some extent by the exigencies of war, which confined them to the analysis and con- struction of only the types of aircraft which were being considered for production. It did not, to any extent, bring about the combining of the best characteristics of different machines of different countries, as might have been expected; nor did it bring about to any extent, the adoption of best engineering prac- tice in aircraft construction. This was due to the fact that the problems of aeronautic en- gineering were too complex to be mastered within a year, even by the best engineers, and the necessity for lightness in construction did not permit the adoption of automobile or naval engineering practice. War Developed Speed Regardles* of Flying Efficiency While collectively the developments in aero- plane construction brought about by the war N-C-1 F-LYING BOAT P-5-L PLYING 50AT SUNDSTtDT-HANNEVIG H-S 2-L FLYING 5OAT McCaughlin STATUS OF . \1MM.IKI) A KHONAt TU K\<;i\ KKKINt; I In- 1 1 .inillrj -I'ajti- iMimlirr ri|iii|i|>nl with I Hull- Itny r motor-.. Our of the first l-inotiirrd planes In ! ]>r,>,lu.vcl. It w.i- luiilt in Great Britain. represent :i stupendous achiex cment. we- find tliat as :i whole tl;c \\;ir rcmiircmciits resulted in sacrificing Hying efficiency for high speed and fa-t climbing. Machines \\cre greatly overpowered and Mich important factors for peace Hying as slow landing speed and high gliding angle were overshadowed by the vital importance of fast climbing and speed. Night Bombing and Antiaircraft Brought About Valuable Developments in Aeroplane Construction The increasing range of the antiaircraft guns jWeed high flying and was responsible for the developing of high ceiling aeroplanes of light 'construction and remarkable efficiency. The extension of night bombing operations brought ahout the construction of larger aeroplanes such as the C'aproni, Hand ley- Page, Vickers, A\ ro. etc. 1 Tin- same thing was true in the construction of seaplanes. The need of Ion if distance air cruisers and torpedoplanes brought ahout the construction of large seaplanes, of which the \arious I'nrtiss types constructed in the I'nit- 1 States and England are representative ex: m- pl- The war also brought about the construction of seaplanes capable of starting from and land- Kvolutinn of the Military \eroplnnc in thr " Textbook of Military \.-ron uitirs." published h\ tlie ('ntim ('... \. Y. r ntii>n of Marine Flying, " TcxtlvKik of Naval \T,,n.nti, s." publish) by the Ontury Co X. Y., for detailed lii-tory of thf evolution of seaplane construction. ing on fairly rough seas. This development is of great importance for Hying for sport, pleas- ure and commerce. Engineering Advantages in Large Machines Large machines permit refinements in con- struction, such as tic use of hollow struts and hollow members, which is not possible in small aeroplanes. This has made it possible to increase the ratio of useful load by over ten per cent, and to get nearer the goal of economic aerial trans- portation. It is hardly necessary to point out that the old theories to the effect that large aeroplanes could not be constructed have been exploded. There can still be found misinformed people who hold that as the thickness of the wings must i'-crease in proportion to the span of the win there comes a point where the weight of the wings is so great that their lifting capacity is not sufficient to lift the machine from the ground. We have heard such foolish arguments, which for the past fifteen years, and up to the Sum- r-er of 11*17, were actually responsible for de- laying the construction of larger aeroplanes in the I'nited States just as the fallacious theory that if one of the motors of a twin-motored plane stopped the plane would spin around, delayed the advent of twin motored planes. They are. at present, to a smaller extent, delaying con- struction of very large aeroplanes. As a mat- STANDARD 'E -4 THOMAS-MORSE 54- 1 1 VOUGHT V.E.7 5E V McC&ughiin STATIS OF APPLIKl) AKKONAITK r.N(.INKI.HIM. te found in the Index, with other aeronautic nomenclature. The helicopter and the ornithopter were con- ceived earlier than the aeroplane. Leonardo Da Vinci designed an ornithopter or Happing wing machine in the fifteenth century. Prac- S*e Appendix for Chapter on I'lywoods and Veneers In Ano- plane t'on-l ruction. The Navy-Curtlss NC-1, the prototype of the Xavy-Curtlss transntlnntir seaplnnrs. \ n,.,,,lH-r of Interesting engineering features are incoVporat.-.! in the .l.>ipn in this machine. T,e pilot is l,K-ate,l outs ami ,1^, the hull. The tail unit is supported by outriggers, instead of being carried on the rear of the 1 ull, a. n in n flying txmt. HANDLEY PAGE O-400 "A.C.E " LAW5ON MT-2 sT.vrrs or AIMM.IJ.D AKUONAITH ENGINEERING tic-ally every ^rcat inventor including Thomas Kdison. OrvilK- Wright. Louis HIcriot, IVter Cooper Hewitt, Kniil licrlincr has. during the J);l.st tit'tci-ll \cars xiveil serious consideration tti the problem of building a helicopter. And v\c may t\|)cct oood results in tin- near future. Now that tfo<)<) t.et. which is hi^hrr than the world's highest mountains, and nmre than 50 passen^, T> |, ;1V| . I,,.,.,, carried m i.iie ill-lit. In l.ict the accc.inplislimeiits of aeroplanes have e\cee<|ed t he ex pectat imis e\ en of those to uhum the suh.ject of aviation has lieen a life study. In spite of these accomplishments, those \\\\<, can see the future of aeronautics from a hroad standpoint reali/.e that in so far as the construc- tion of an aeroplane is concerned, aeronautics is in exactly the same position to-day as the art f shipbuilding would he if ship boilden had (inly reached the sta^c of building racing boats and small yachts! Analogous to the racing boat we have the speed aeroplane. The War has necessitated the design and construction of small inaehiiu s. whose prime requisites \\ere jjreat speed and nianoL-uverahility to be Used for combat pur- poses. Several successful designs were worked out, especially on the other side. The small 'I'lii- " i-Vlixstowe Fury," Uie Porte triplane tl> inir boat. This monster flying boat, thr larp-st in cxlstrncr. Is Hriti.-h mi- with Hritish rnfri'nrs. It is fitted with five Hnlls-Hoyrr " Knfrlc-s " rnfrinrs arrnnfml In tandem wt* and ant sinflc lii-r." l'ri|>l.iii< service Ix-tMri-n Paris and I-onclmi fnrtahle <-al)in. il oom- wing area and high landing speed of these planes make them suitable- only for \cry expert han- dling, and for enjoying all the thrills and stunts of expert flying for sport's sake. \\ arc | list beginning to liuild low priced aeroplanes which will represent in aeronautics the equivalent of the motor boat. There are already small aeroplanes with a wing spread of IS to 20 feet, capable of going at a speed of 60 to HO miles per hour, traveling about '20 miles to the gallon of gasoline. These small planes represent in aeronautics what the motor boat represents in the marine field or what the Ford and Dodge cars represent in automobiles and will be powerful factors in popularizing avia- tion. Hut as regards large aeroplanes. \\e have only in to build the equivalent of small yachts and to go beyond this brings up a large number of problems. The Navy-Curtiss Flying Boats have a wing spread of J-jf, feet; the chord and gap of the planes are !'_' feet. The machine is driven by four Liberty engines of 400 h.p. each. A speed of over 80 miles has been made, and in ten minutes the machine has ascended to a height of 2000 feet. Fully loaded this mac bine weighs 28.000 pounds. It can carry a useful load amounting to more than six tons. A more comprehensive idea of its carrying capacity may be had from the fact that, on one trip .)() people have been carried. While there are several planes under con- struction at the date of writing which have a wing span of up to 100 feet, the \C type sea- plane and the Ilandley-Pauc aeroplane may lie said to approach the limit in biplane construc- tion. It is apparent that to double the si/e of the XT it would be necessary to find a new way of distributing the surfaces to lift such a large flying boat. The four-motored Ilandley-Page air cruiser, which can carry 4' | is and which nas given some fine demonstrations, is about l.'iO feet in span. It is apparent also that this type of plane could not very well he double:! in si/e without devising a different method of distrib- uting the amount of surface requind to lift a machine of such proportions. Caproni has built a 5000 hor-e powered tri- plane and is now working on larger planes. He has gone further in experiments with tri- Detailed Views of NC-4 Transatlantic Type Seaplane 1 Forward part of hull. The ladder leads to pilots' cockpits. 3 The commander's cockpit at the extreme front of the hull. 5 "Wing tip float under the lower left main plane. 7 The hiplane tail group. There are two fins and three rudders. 2 One of the power units, showing streamline engine nacelle. 4 The pilots' compartments showing special compass installation. 6 Pilots' compartments as seen from the front, showing windshields. 8 Side view of front of hull, showing placement of the navigator. sT.vrrs or .MMM.IF.D AF.KOX.UTU KN^INKKKIM; fummmiinii Ilir \I.-irt.ii "Mini- Mini" ,,,,,1 tl,,- \larlin " I ..,-],. " \ niM |, N , ,, M . ,,.,;_ ,|,,. ,,,,. () \, m . ri , an ,,,-n,HMiili.' <-n ftaeer. II., " Kin,- Mini" has wi,,i..s ,,,,h Is ,,., , ,,|,. ; ,,,,| ,, nh u ,,.,,,, ..,, ,,, s _ wi((| . m(i||ir ^.^ ^ |if (|| h ^ |( wi|| ( ^ ,.n nu , Mimtry r,,.,,l ,n,l p, ,,|,,,,il .'n mil.-s ,, L ..,||,,,, ,,f ^.M.li,,.-. II,,. Martin " l-:,,|rlr " is <-<|iii|,|-,l uilli tv,, IIKI kp I . ''"- i "" 1 is r;lt " 1 '" ' ; ' rr > ' l ""- " ( "--f"' l " ; " 1 "'' ( " IW ., rmisinp r;i.lin> ,,f OTCt .'"'Mi mil,-,. M,,tl, i,,arl,in. ,'- bet of renwrkaMe n-- engineering f.-,(nr,-s iii<-|inlin K tin- K-l.ar ,-,-llul,- truss, tlie retractable c-hawiis, ,-tc. Tli,- \ arf , r m...-liiin- has i drive truumiMion t,, UK- |ir,i|>,-ll,-rs. plain--, tlian ninst ul' tl.c o!ln-r (lesion, -rs and lie f ln-rd'uiv lias : antarc s i;i that direction, lint in plaiinintr his larger | l.iin-s !:< als. finds it necessary to ado;>t diilVn-nt | rincipK-s in ciis- pMsin-r of the enonni>"s an u m ,-i ssary to oh- tain the desired lii't he will ha\e tandem tri- planes. In order to hrin^ the aeroplane up to tin- standards set I iv iiiarini- einistruetors. we must de\elop a earjro earryin^ tyj-e of plane. It is (Mivions that the eoiiiinereial value of this type of niaehine is enonnoiis. Although we do not hope, at least for the pre-ent. to en-ate machines eapahle of carrying as iniic-h load as an ocean goin^r steamer, we do require a (ilane that will carry a sufficiently heavy load, which, taken to- gether with the \ast saving in time, will make the final tonnage transported close enough for coiiiparisiui. ; The Ctlt-nn I.. Martin twin inotornl hiplnnr, rrs. Getting the same Engineering Results by Different Distributions of Wing Area Bristol Triplane, Type Bracinar with 4 I'unia Engines. ' The Pemberton-Billing quadruplane. Designed by the English aeronautic enthusiast. The height of a machine of this type be- gins to be a serious problem, both in landing and in housing it. Experimental Tandem Biplane of ( olli.-x Jeans.m. View of machine taking off. Wing area, US sq. meters Span -X meters It is equipped with i motors of 300 h.p. each. Weight of machine, 3700 kilos. 14 STATt'S OF APPI.IKI) AKKON.U TIC \-.\C, I N KKHI N(. HANDILY PACE: BIPLANE: AB.E-A 1.648 5 r T /PAN - UPPER PLANt WO FT -LOWIS.70F-* CHORD IOF7 SHADED AHCAS INDICATE T^ LOWfcR PLANE- -A ( ) A" CUBfUCl N-C-1 HYING 50 AT AEtA tE PlANt \16 F T -LOWtB.96 T- T J CHORD 1 FT 2PT BIPLANE- WITH AWING ARtA Of- 10.00O ./PAN, E>OTH PLANtS. 171 FT CHORD 28*7 INCH fry -iow Can We Distribute the 10,000 Square Feet of Wing Surface Required to Lift 20 Tons of Useful Load? For commercial success the aeroplane should e Iniilt to carry 'JO tons of useful load. How can the 1O.IMM) square feet of wing siir- e required to lift this useful load lie dis- rihutedf It would he absolutely out of the uestioii to think of constructing a monoplane f that area. Since experiments have shown ie most desirable winj; proportion is to have ie spun ahout six times the width of the plane, r in other words, the aspect ratio should be bout > to 1. This would mean that in order obtain 1(1.000 square feet of surface in a lonoplane. its surface would have to be 244.8 .et in length or span, and 40.8 feet in width r chord. 1 1' the same area is to be obtained in a biplane, rvinjr the .same aspect ratio or span to hord relation, our span would be 171 feet and 'tc chord -_'K..) feet. It is claimed tHht when ir faces are superimposed the full lift is not ob- lined from all the planes. In the triplane the ft of the middle wing is somewhat decreased eeause of the interference of the plane above nd the plane below. Some engineers have ven gone so far as to claim that the middle plane ^i\es practically no lift whatever. This. of course, is a mistaken notion. Provided that the gap between the planes is great enough, each of the planes is as efficient as a monoplane sur- face. The middle plane gives a decreased lift when the adjacent planes are placed too close to it, for then the air flow is interfered with. It remains with the designers of triplancs and mul- tiplanes to determine the aenxlynamical effi- ciency of the aerofoil. Structural advantages are to be had in tri- plane and multiplane combinations and very often the disadvantages resulting in decreased efficiency of the wings are more than offset by the structural advantages gained. If we tried to build a triplane with lo.mm feet of surface it would have to be close ' feet high. Here comes the difficult problems of landing. We recall that the Avro triplane at the lioston- Harvard Meet, September. 1910, had the tend- ency of toppling over at the least cause. That machine established a traditional prejudice against triplanes and quadruplanes. But the height of aeroplanes has gone up ; and although 16 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING MONOPLANE- ./PAN 244.5 ?! CHORD 40.8 F-T BIPLANE yPAN 171 PI CHOP-D 3 PLANED 4 PLANE./ 1 5 PLANE-./" -E -i- E-E ./PAN 141 CHORD 23.5 /PAN 121.6 CHORD 203 JPM 109.2 CHOBD 18.2 COMBINED MONOPLANES AND BIPLANES 5 PLANED 7 PLANED 1 12 PLANED 8 PLANED J'PAN 86.4 CHORD 14.4 109.2 CHORD 18.2 ./TAN 92.4 CHOBD 19-4 ./PAN 7O.2 CHORP 11.7 COMBINED BIPLANES AND TPlPLANf ./PAN 141 PT CHOBD 23.5 PT 10 PLANty Z5 PLANtv/- JTAN 92. A CHQKP 15.4 yPAN 77. 4 CHORD 12-9 ./'PAN 48.6 CHORP B.l COMBINED TRIPLANLV & QUADRUPLANE,/ 1 17 PLANED QUADP.UPLANE yPAN 121.8 PT CHOBD 20.3 PT 15 PLANE,/ 63 CHORD 10.5 -/"PAN 48.6 CHORD 8.1 ./TAN 59.4 F-T CHORD 9-9 FT MULTIPLANE COMBINATIONS the prejudice still remains, the height of aero- planes is increasing year by year. The Porte triplane is over 27 ft. 6 in. high; the Caproni tri- plane is over 19 ft. high, the Gotha-Zeppelin is 21 ft. high, the Voisin triplanes are 18 and 19 ft. high respectively, the Handley-Pages are from 18 to 20 ft. high; the Curtiss NC is 24% ft. high. Such a machine as* proposed would possess a high center of gravity and would be apt to over- turn on landing, due to inertia, unless the body and lever arm were of sufficient length to coun- teract this force. Then also we must consider that it would necessitate a hangar of unusual structure to properly house such a machine. This is one of the allied problems which come up when unusual planes are contemplated. When Handley-Page built his large biplane, in 1916, and adopted a ten-foot chord, instead of the conventional 6%-foot chord, he started a new development. He demonstrated the possi- bility of using a greater chord to solve the prob- lem of building larger planes without going into extreme wing spans or excessive heights. But while adopting a greater chord may be a partial solution in building an aeroplane with 5000 square feet of wing surface, it does not afford -a practical solution in building a plane with 10,000 square feet of surface. We- must, therefore, turn to new sources for solution of the problem of distributing 10,000 square feet of wing surface in order to lift the 20 tons of useful load referred to above. The following table has been prepared to show how an area of 10,000 square feet can be disposed and divided into from 1 to 25 planes, each preserving the proper aspect ratio. STATTS OF AIM'TIKI) AKU< >.\ ATTIC F..\ ( . I M .1 .H I \(i Area Distribution, Wings with Aspect Ratio of 6 to 1 17 \iinilirr of Surl 1 -. i III 11 19 l.t 11 l.i u II I- II .'II .'I lull Siirf.Kv (M|. ft.) III.IHNI .'..IHMI -VVMI .'.INK) I.'. '.i. l.l> 1,111 1.IMMI ...... -- ,,, 400 4JV I il 416 400 l'h.ir.1 ( f.,-1 , I-..' I'M, I.-..J 111 11.7 ll.li Kl.l 9.9 9.6 9.1 -.i 8.4 8.3 8.1 Sp.ni i;i .u iii.n ttU -i n 7u..' H i MM, 39.4 57.6 .'.I. i. 41.0 IM i- ii It is noticed that in flic larger aeroplanes the aspect ratio tends to increase. Fur example, tin Handli-y-1'a.ne lias a ratio of 10 for the up- plane and 7 Tor tin- lower. Tins IN true als,, of tin- Caproni Triplaiu- \\lu-n- the aspect ratio of all three planes is aliout Id. Where : , on-atrr aspect ratio i<, under consideration land the trend of design in lary;rr machines leads us to the adoption of greater spam a different tal.l. of dinieiisions. would, of course, he necessary, hut the one sho\\n ahove ^i\ " wliidi is , Mi-nun: p i~. HL-. -r. U-t,,- n I'.irU Mini l.iniiliin. Thr .' 'nu|.ir> arc rnrlosed in strcain- Im. .1 n.i.-.-IIrs in .iril.-r In drrrrusi- Hi.- resistance. struts ;iii(l bracing :iiiil tin- resistance they pre- .SCllt. of finding proper relation between the gap and chord, distances between sets of planes and of the reduction to a minimum of parasite resist- Tandem Planes Represent the Solution a nee. Thr lirst possible solution tllilt suggests it- sell' is that tin- 10.000 square I'cct of wing sur- face lie distributed in Tandem Plant's. Hut what should the Tandem Planes he? Mono- planes' Hi|. lanes.' Multij Liu's? Tlie first noteworthy experime its with Tan- dem plains \\cre made by Sainucl P. Lan^ley. Sinee'then a nuinhi-r of experiments have been made with tandem planes hut few of the experi- menters have had the opportunity of testing triplanes and ffettin^ aenulynamieal data so as to ascertain the relative efficiency of Tandem 1 Manes. This is a tremendous field and here the aeronautic engineers will have to find the correct relation between surfaces that are dis- posed one above the other and in Tandem Planes, the distances between the planes or groups of planes. If three or more sets of planes are to he used, then the problems multi- ply. for. then will come in again the problem Problems of Trussing and Bracing The employment of many lifting surfaces, either superimposed or adjacent, will necessi- tate new structural methods. In this field, our engineers and bridge builders can help us. \\Y need the simplest forms of structural stiffening. in order not to create too much parasite resist- ance. By dividing up our wing area into many small planes, the loading on each plane will IK.' comparatively light, and consequently it would seem that a light but sufficiently safe structure can l>e used for these wings. (See in Appen- dix article on the Evolution of Aeroplane Wing Trussing.) Body Construction We will assume that the distribution of the 10.000 square feet of wing area necessary to lift \ C.iunt Hriti-li Flyintr Boat, driven by three motors a(rfrrr(tatin(f HMHI li.p. Thfc boat wa* used by the British at Helip.l.ui.l I.itrlit for patrol duty It lias a larfre rruisin(r radius and rnn carry a considerable load. A reconstructed plane of thin type will tnaki- a jrixHl type of commercial passenp-r and freight carrier. The interior of a Handlev-Pape, electrically heated passenger carrying biplane used for regular passenger carrying air lines The " Braemar" Mark II Bristol Triplane, driven by four 400-h.p. Liberty Engines. It has a wing span of 82 feet, and carries a useful load of 8,000 Ibs. 20 STATl'S OF Al'I'I.IKl) AKRON ATTIC KN<; I N KKRI Ni. llritMi Ariiistn.ntf WhiUnrth l.'ii.iilrii|,|.nit- uill. a I in ti |> I i ML'im- It is ii two s.-atrr, jfrnrral utility lu.K-liiiif ntiil inakrs a spi'.h. nt (rround Irvrl. This wait onr of the first quadruplanes to l.< l.uilt. JO tons o!' cargo has been successfully worked out. At this point we art- confronted liy an- other serious |>rol>Icm. I low arc we going *" construct a body or fuselage for this Multi- plain-' We must provide spaces for the cargo in such locations as to make them readily access- ible, and at the same time to make the moments ahout the center of gravity of the whole machine either comparatively small or else nicely cmial- i/.ed. in order to prevent undesirable flying de- fects. The problem of furl storage is also pres- ent. The machine would be multi-motored, and the location of these motors and tin ir fuel sup- plies will involve a large amount of careful plan- ning. Furthermore, if our plane is to be a passenger carrier, comfortable (|iiarters must be provided. Hire again \\e must try to emulate the stand- ards of yacht and ship builders. We should try to locate our passengers so that they could obtain an unimpaired view, since the latter is of the supreme joys of an air voyage. The type of multiplane will also involve proh- l< ins. If it is to be a flying boat type, it must be made strong and seaworthy, and at the same time not unduly heavy. If we are planning a land niaehine, the landing gear must he propor- tioned to wi'hstand the heavy loads with a good factor of safety and yet not offer too mueh air resistance in flight. There follow herewith the designs and details of construction of practically all the important types of aeroplanes in existence to-day. The engineer is, therefore, enabled to compare them and see what the l>e.st aeronautic engineering practice of different countries is. Sikorsky I i|i|ane r<)ui|>|-ci with 4 Argus motors of I4O h.|>. rnrli was tin- |>n>tuty|H- of the iiiiilliiituloriil plane*. 22 TKXTBOOK OF APPLIED AERONAUTIC ENGINEERING This 1917 Sikorsky biplane was equipped with 4 Renault motors of -'-0 h.p. each. It was built in Russia. A 5-motored German Giant Biplane. In the nose of the machine is an engine driving a tractor screw. The other four en- gines are mounted in tandem sets of two. A machine of this kind represents a possible type of commercial aeroplane of the im- mediate future. However, it can readily be seen that the proportions of a machine of this lifting capacity are approaching a limit. Some other method of distribution of the aerofoil surfaces is needed to obtain a still greater lift. A view of the Forward nacelle showing the covering of the front motor, the radiator mounting, etc. The observers have an excellent view, both ahead and behind. The two sets of tandem motors in the German 5-motor Biplane are mounted on long engine bearers. They dri their propellers through gear boxes. The cutting-out of t trailing edges of the wings for pusher propeller clearance thereby avoided. The importance of using geared drive f weight carrying aeroplanes has been fully demonstrated. CIIAI'TKH II MULTI-MOTORED AEROPLANES The 5-Motored German Biplane Complete details of this m.-irliinr ;irc not axailable at the present time. Tin- wreck of our of (lie bombing machines of this type \x is can fnlly studied by members of (lie Brit- ish Technical Department :iMil :in approximate idea of its construction xvas obtained. Tin- power plants are arranged as follows: In the nose nf the inachiiie is one engine drix ing n tractor screw. On each side of the fuselage, supported by the wings, is a long pair of engine hearers, carrying two engines apiece, which drive tractor and pusher screws, in a manner similar to that employed in the earlier designs of the Russian giant plane constructed by Sikorsky in I!IM. The engines used are the Max bach 300 h.p. standard ti-cy Under \ertical type, driving the propellers through a \-i>\ and driving shaft. This necessitates the employ- ment of a My wheel on the engine, to which is added the female portion of a flexible coupling. The .rear box casing consists of a massive aluminum casting provided with four feet which are bolted to the engine 1 carers. Two kinds of gear boxes are employed. These differ only in oxer all dimensions and the length of the propeller shaft. The larger type is used for the pusher screw in order to obviate the necessity of cutting a slice out of the trailing I the main planes. In each case the gear reduction is 21 41. Plain spur pinions are used having a pitch of 22 mm. and a width across the teeth of ~."> mm. The diameter of the smaller of the driving pinions is 162. ."> mm., and that of the larger pinion 282 mm. The larger pinion is considerably dished, but the web is not lightened by any perforations. The oxer-all dimensions of the longer gear box is as follows: I .u-th. Iii2.'> mm. Hreadth. 673 mm. Height. .">.'<;> mm. The driving pinion runs on two large diameter roller bearings carried in gunmetal housings supported in the inner end of the gear box. This part is split vertically, and united by the usual transverse bolts, whilst the conical- shaped portion of the box is solid. The usual oil-thrower of helical type are fitted. 23 At its outer end the pinion shaft terminates in a ring of serrations which engage with serrations provided in the male portion of the flexible coupling, these two parts Ix-ing held together with bolts and clamping plates. The engine is thus close up against the gear box. in contradistinction to the design of the (-engine power plant. There i* pmr- 1 1< ally no external shaft at all. The larger pinion is mounted on a hollow shaft of !'.' mm. diameter, carried on roller bearings at each end for radial load and furnish- d at the nose end with ball thrust hearings. In the shorter type of gear box the larger pinion shaft is left solid, and it would appear that the gear box casing, instead of being made in three pieces, is made in two pieces, i.e., the whole box is simply split vertically. The smaller pinion shaft projects right through the gear box, and at its outer end carries a projection fitted with a small ball thrust race. This projection acts as a drive for the oil pump, which is mounted on the oil radiator used in connection with each gear box. It is worthy of notice that the German designers have fully realized the importance of using geared engines for weight carrying aeroplanes, and are apparently satisfied with the external gear box principle, although in this case they have made it a very ponderous affair. Needless to say, a great amount of the weight could have been saved if 12-eylinder engines had l>ccn used instead of 6-cylinder. The weights* of the gear box and its attachments are an follows: Gear box, long type. HO Ibs. Fly wheel and female clutch, 11 Ibs. Male clutch. ;. Ibs. Oil radiator, 12" L . Ibs. This, it will Ix' seen, represents, an additional weight of considerably more than 1 Ib. |x-r h.p. The oil radiator used in conjunction with each gear box is of a roughly semi-circular shape, and is slung under- neath the main transxerse members of the engine bearer* so that it comes immediately beneath the large feet of the gear box. This radiator is entirely of steel construction, and embraces 65 tubes of approximately 20 mm. internal diameter. These are expanded and sweated into the end plates, to one of which is fitted a stout flange, against which is bolted a small gcnr pump which constantly circu- lates the oil from the gear box case through the radiator. This gear pump is driven by a flexible shaft from the small pinion, the shaft and its easing being in all respects TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING similar to those employed for engine revolution counters. This flexible drive is taken off a small worm gear. Underneath the oil pump of the gear box proper an elec- trical thermometer is fitted, which communicates with a dial on the dashboard. It is a little difficult to see what object can be served by this thermometer, unless it be to indicate the desirability of throttling down a little in the event of the oil getting unduly hot, as there is no apparent means of controlling the draught of air through the oil radiator. Fitted on each gear box and working in connection with the oil circulation is a filter. This is provided with an aluminum case and a detachable gauze cylinder through which the oil passes. The arrangement of the gear box is such that the axis of the propeller is raised about 220 mm. above that of the engine crankshaft. The construction of the long engine bearers is not with- out interest. Each bearer consists of a spruce or pine cen- tral portion, to which are applied, top and bottom, five laminations of ash. On each side are glued panels of 3-ply, about Vs in- thick. The engine bearers taper sharply at each end. and are strengthened by massive steel girders under each gear- box. The screws revolve at approximately half the speed of the engine, and having therefore a moderately light cen- trifugal load to carry, are made of a common wood that would scarcely be safe for direct driving screws. The diameter is K.'iO meters and the pitch 3.30, for the pusher screw, but it is not possible to state whether the tractor screws are of the same dimensions and pitch. The construction is very interesting; each screw is made of 17 laminations of what appears to be soft pine, and these laminations are themselves in pieces, and do not run continuously from tip to tip. They are, of course, slag- gered, so that the joints in successive layers do not coin- cide. Two plies of very thin birch veneer are wrapped round the blades. The grain of this veneer runs across the blade instead of along it. It is difficult to say from the appearance of the screw whether this veneer has been put on in the form of 2-ply or as two separate layers, one after the other. The engine control consists of five stout steel tubular levers. The levers are fitted with ratchets, so that each one can be operated individually; but the presence of the large-diameter toothed wheel in the center of the lever shaft would seem to indicate that all five levers could, when desired, be controlled simultaneously. The Douglas type of engine, carried for the purpose of driving the dynamo of the wireless and heating installa- tion, is used. The engine is a very close copv of the 2% h.p. Douglas and is made by Bosch. The flv wheel is furnished with radial vanes which induce a draught, through a sheet-iron casing, and directs it past cowls on to the cylinder heads and valve chests. The generator is direct-driven through the medium of a pack of flat leaf springs, which act as dogs and engage with the slots on the fly wheel boss. An apparent transformer, used in conjunction with the wireless set, was also in use. The tail skid of the machine is built up of laminations of MULTI-MOTORED A KUOl'l.A \ ES 25 jisli and is furnislu-il with :\ lieax y s|< < 1 slim- .unl .1 large unixersal :itt;iflinii lit. The 4-Motored Voisin Triplane In order to axoid eonstructiiii; a machim >! huge pro- portions in order to obtain the desired lift, tin- French haxe taken a step in tin 1 riylit direction in distributing into thriv planes thr necessary aerofoil ana. Tin- Voisin triplanes .-in- an example of this type of machine. They arc powered with four motors, operating in a manner similar to those on the Handle] chine. The tail is supported liy streamlined oatn_ as shown in tin- illustration In-low. The 4-Motored Handley-Page Biplane This Iriijc niai-hiiii- was designed by Mr. Joseph Hand- .11 Kn^lish aeronautic engineer of over ten v ears' experience. It is powered with four Itolls-Koyce or Lib- erty motors, mounted in pairs. one liehind the other and driving tractor and pusher screws. The niacliiiie is capable of carrying more fuel and use- ful lo .-id than would In- required to cross tin- Atlantic In November. l!Ms, forty p isscngers were car- ricil o\i r the city of London in a maeliine of this type, and a month later a flight was made trout London to Cairo and from Cairo to Delhi. India. These demonstrations established this type of plane as a longdistance passenger and mail carrier. The 4-Motored Sikorsky Biplane The originality and energy of the Russian aviator and inventor. Mr. I. I. Sikorsky, made him one of the pioneers in the design and construction of huge, multi-motored bi- planes. In the sprinsr of 1913, his first giant aeroplane was ready to lake the air. II. called it the " Uiissi.m Knight." In general arr in-einent. the " Kiiss, HI Knight" was ch iraeli ri/t d ly a xery hm^. shallow liody. nliotit IS) in- It rs in h iiiilh. nhoxe which the cahin portion extended for a conaiderable distance. Tin ~p.::i ot its win^s is '' rs with a chord of :i meters. A monoplane tail and four vertical rud.h rs constituted the (nil units. The cahin portion of the mai him- forms the most inti r- eslin;; feature. It was dixidrd into three compartments. In the front one wen t.. s, ,ts. ..n. on e-i h sid, (if the cahin, in front of which were the dual controls. \.ir mally the controls on the hit win- the main ones, and in front of them were mounted all the various instruments. Between the two s,,ts was an open space hading to n door opening out on to the open part of th< hody in the extreme n.-si I-' nun here observations could l>e made with ease, as the position was so far forward ns to Ix w. II clear of all obstructions. For use at night n searchlight was placed right o:it in the lx>w, where it would not ila/./li- (lie pilot but would i'luminatc the landing ground. The central portion of the cabin was set aside for the accommodation of pass, M-, rs As was to be expected in a machine so elaborately equipped, the passengers were not asked to si|ucc/c into seats of the ordinary bucket type. Chairs, well upholstered and not fixed to the floor were pi -iced alongside the windows. Communication between passengers' and pilot's cabins was by means of a glass door, and thus any passenger could walk through the pilot's compartment out on the <>|>cn front portion of the body, where a more unobstructed view was obtainable. From illustrations, the doors leading out into the open appear to be. instead of sliding, of the swinging pattern. so that opening them against the pressure of the air may have been attended with some difficulty. To the rear of the passengers' compartment was n par- tition, with a door leading to the aft cabin, which was divided into two parts, one part of it being set aside for housing spare parts, while the other contained a sofa on X v- x The t- toreil Voisin Tri|>liinc. The rec|iiireni|ii>rtii.iis c,i (lie whole machine to a reasonable standard. 'l"h** . : . Dia,;rii.iiiiiatic view of lln- constrii; lion of thr /.cp|tclin l-motorcd Iliplimc. Tlir ue.-tr li\ consists ot a casing i>f aluminum, prov ithcl With ffiiiljll^ f',11-.. Mi-ni-.ilh c. it-li i;r.-ir t-.iM i> .-i >in;ill r:uli:itor fur cotilin)! tin- liilirir.'itin-z "il cirt'ul.-ili il tlinri^li tin- rnu'ir-. This r-nli-ittir t-Kii-ists of ;i tl:it si-nii-cirt-ulnr tank, fitted with iruni-ro-.i- (T.-ITI-M r^t- Cil't--. .it fairly Inrj;c ilinmctcr ( about -,'n nun.) in a ni.uiiie r similar to that of n honryromh ratli- ntur. A pump Miiiiintcd at the linsr of the radiator is also ftirnislii-d with an electrical thermometer, giving a reading on i ili il in tin- ciu-kpit. i-iii;ini' !< fitted with a self starting arrangement of the tv|x- usually fitted tt> Mavhat-h motors. The exhaust pipe may he closed l>y mean-, of a shutter, and all the cylinders can l filled with gas from the carburettor by - of a large hand-pump, for whi;-h pur|x>se all the \al\es are held open. \\'ht n these valves are closed, and the starting magneto operatitl. the engine tires aiiil con- tinni-s running. Kach engine has its own radiator, whh'h is in united directly above it. and supported by stnts and 'ires at a point about half-way In'tween the top and ^i planes. These radiators are of the usual type. They are rectangular in shape, with their greater length placed hori/.ontally, and the radiating surface consists of i zig-zag tubes placed vertically. The engine hearers consist of stout ash spars, reinforeed with mulii-ply wood. The engine controls appear to be made chicHy of ash and covered with a thin veneer. Wing Construction Tin spars are built up very elaborately in sections, and consisting of no less than seven sections of spruce, rein- forced with multi-ply on each side, and finally carefully it! with doped fabric. The spars of the lower wings are continuous, that is to they run right across tile center section of the fusel- age, to the longerons of which they are secured, contrary to the usual practice, in which special compression mem- bers, forming part of the fuselage construction, are em- ployed. The wing surface, both upper and lower, is di- vided into three sections, of which the middle section ex- tends to the engine mountings on each side. Tl.i spars in this section are both at right angles to the axis of the fuselage. At each side of the middle section the leading edge of the wings is boldly swept back as well as tapered. The rear spars of the wings, together with those of the center section, form a straight line from wing-tip to wing- tip, but the front spars are swept back. Tin ribs are built up, and of girder form. Between the leading edge and the leading spar, numer- is extra ribs occur in addition to the main ribs. Internal bracing against drag takes the form of steel tubular com- pression members and steel cables, the former being placet! at a point coincident with the attachment of each inter- plane strut. An additional bracing is installed, of which the compression member consists of a double rib placed half-way between the struts. In each case the bracing wires pass obliquely right through the spars. The ribs are mounted parallel to the line of flight. The dis|>osal of the spars is as follows: Top Plant Leading eclfre to center of leading spar. . . 1 ft. 9i/ t in. Distance lietween centers of spurs i ft. ~'/in. Trailing edjre to center of rear mnin spar 5 ft. lloltom Plant 1 .ratlin? edfrr to center of lending spur. . . 1 ft. TV, in. Distances U'twern centers of m.-iin spurs. 5 ft. I in. Trnilinjr edge to center of rear main spar 5 ft. (approximately). The trailing edge of this aeroplane was too badly dam- aged to permit of this measurement being given accurately. 30 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING fofa/e >,t "00 F,0. 3 eH. - Avion .n, Zm.ll* - E ^^,- ^ n ^Ti"^ n ^^^^^ ^'^ ^^' """ ~ ""* "' ""' Giant Zeppelin Aeroplane, al - duralumin; b wood; c- cable; f - steel cable; g- sheath; t tubing. Between the interplane struts the rear spars are thinned down in width, but their depth remains practically constant from root to tip. Such tapering as exists is so arranged as to promote a decided wash-out of the angle of incidence near the tip. This is done by tapering the front spar on its upper edge, and the rear spar on its lower edge. Ailerons These are on the top planes only, and are provided with a framework of steel tubing. They are not balanced, and the controls are led in the usual manner through the bot- tom plane from the aileron lever. The span of each aileron is 22 ft. 5 in., and the chord 3 ft. 4 in. Inter-plane Struts These are of large-diameter steel tube, covered in with a streamline fairing consisting of three-ply mounted on a light rib-work of wood. Bracing The attachment of the bracing cables to the spars is somewhat similar to the bracing of the Fokker fuselage; that is to say, the wires, instead of being anchored at each end to an eyebolt, are double, and are looped round the spar, to which is fixed a grooved channel-piece for the reception of the cable. It is difficult to see that any ad- vantage is gained by this arrangement. Tail Unit A biplane tail, somewhat similar to that of the Handley- Page, is fitted. The fixed tail planes, the angle of inci- dence of which can be adjusted through small limits, are of wooden construction, and have the following dimen- Span each side of fuselage 12 ft. 4 in. Chord (average) 4 ft. 10 in. Gap 6ft. 9y s in. The Bristol Bomber Triplane Type "Braemar" with 4 Puma engines. The motors are mounted in tandem pairs. Ailerons are fitted to the ends of the two upper planes only. MULTI-MOTORED AKKoi'LANKS virw of the liristol 1-inotorccl llraemar Tripl.uie. The continuous middle wing over the fuselage is an interesting feature. Elevators Tin se arc fitted to both tlir top .-mil bottom tail planes. and ari ..( .iliiiiiiiiiiin construction. tin- rilis. being of girder form, sunn what similar in construction to tin ribs of the mum planes. Tin ili 'valors ari- not balanced; the top and l)ottom delators. are titled with independent control levers. lint arc prcsiimalilv operated together from the control .stick. Their dimensions arc ax follows: S|...n .............................................. -". 6 in. Choril ;.t lip ....................................... -'ft. tin. Chord lit center .................................... I fl. i". Fins There are three fins; two outer ones forming interplanr struts, and an inm-r central one of triangular shape. Rudders The framework of these orirans is hiiilt up of aluminum. There is also a quadrant nt the foot of the rudder posts by means of which the\ are operated; each rudder |K>st it fitted with ball bearings, both top and bottom. Undercarriage Beneath each engine section is an undercarriage consist- ing of a massive axle fitted with four wheels at each end. This axle is attached by india-rubber shock absorbers to the tubular steel V-struts which form extensions of the engine bearer struts. A third undercarriage is mounted under the forward pnrt of the fuselage, and consists of an axle with one pair of wheels. Photograph of the famous IV llnviland 10, which is being used in the London to Paris passenger service. This machine is equipped with two Koll.s-Hoyce motors, and has a maximum speed of 128 miles per hour. 32 MULTI-MOTORED .\KK< HM.ANK The I > \ ,.\ i urti-- No. I. (ir-t to cro-s tin- \tl.intic The U. S. Navy-Curtiss No. 4 Transatlantic Seaplane Tlii- \( Type of Hying boats constructed liy tin- Cnrtiss Cn!ii|i.iiiy. represent- strictly original American elcvelop- IM. tit. Tin- design was initial, d in the Fall of I!H7 by Rear Ailmiral I). \V. Taylor, chii-f constructor of the I S. \.-i\y. The big boats were designed for weight carrying and it was intended to use them in eomlritini; the submarine menace which had assumed alarmini; pro portions in 1!>18. The NC-1 was completed and given her trials in October. I'.US. Since that time the NC-2, \i ''. and NC-1- followed in quirk succession. Fully loaded the machine weighs 28,000 Ibs. and when empty ( hut including radiator water nnd fixed instru- ments .-mil equipment) l;>,K7t- Ihs. The useful load avail aMe for crew, supplies and fuel is. therefore, 12,126 Ibs. or oxer I-:! per cent. This useful load may be put into fuel, freight, etc.. in any proportion desired. For an endurance High) there would be food, v/ater, signal lights. spare parts, and miscellaneous equipment (52 } Ibs.), oil (7.10 Ihs.). and gasoline (!K5.0 Ibs.). This should suf- fice for a flight of 1100 sea miles. The radio outfit is of sufficient power to communicate with ships 2OO miles away. The radio telephone would be used to talk to other planes in the formation or within x'5 miles. The principal dimensions of all the NC Machines are as follows: General Dimensions Span, upper plane 1 36 ft. in. Spun, lower plane 91 ft. In. Chord I.' ft. in. Gap, maximum 13 ft. 6 in. Gap, minimum I -1 ft. in. I-ength overall 68 ft. 3% In. Height overall 34 ft. 5% In. Areas Main planes (including aileron-) Ailerons , Stiiliilizrrs Rudders Elevators Fins Of. /I 905 40 79 Angles tn hull . . Kn^ine- to hull . Staliiliftcr to hull Dihedral, upper . . Dihedral, lower 3" 0* r 0" 3 s Weights Pound, Machine empty !5,H?i Fully lomlrd iHjOOO Csefiil lo.id I Weight per l>.h.p 17.i Tank Capacities Gruvitv '/of/on* . 91 Fuel 1.800 Oil . 160 Performance Knoll Speed rnnge for IHflM Ilis 74-58 Speed range for J4/WO Ibs 84-53 Main Planes Considerable research and experiment was necessary to determine the best disposition of material to adopt for wings of this si/e. The R. A. F. 6 curve is used. The structural weight of the completed wings is only 1 ' .. pounds per square foot, and they can carry a load of 11.7 pounds. Wing spars are of spruce, box section. Ribs are made up of spruce cap strips tied by a system of vertical and diagonal strips of spruce. Each rib weighs but '2fi ounces. On test they were required to carry a proof sand load of 1AO pounds for 21 hours without showing signs of weakness. The leading edges of main planes are hinged to permit accessibility to the aileron control cables, which run con- cealed in the wing. Interplanc struts arc of unusual construction. Tliev are of box section spruce, faired off to a streamline shape by -tiff fibre. To reduce any tendency of the struts to 34 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING with 4 Liberty motors bow under load, the middle points are connected by steel cable. The metal fittings where struts and wires are fastened to the wings presented a serious problem. The forces to be taken care of were so large that it was necessary to abandon the usual methods of the aeroplane builder and adopt those of the bridge designer. All forces acting at a joint pass through a common center. In this case, as in a pin bridge, the forces are all applied to a large hol- low bolt at the center of the wing beam. In the design of the metal fittings to reduce the amount of metal needed, it was decided to employ a special alloy steel of 150,000 Ibs. per square inch tensile strength. To increase bear- ing areas, bolts and pins are made of large diameter but hollow. The upper plane is in three sections ; center section 25 ft. 6Vi> in. in span. Lower plane in four sections ; inner sections of the lower wing are built into hull. There is a clearance of ^4 inch between outer and inner plane sec- tions. Outer lower sections have a 3 dihedral; elsewhere plane sections are in flat span. Ends of struts supporting middle engines are centered 50% inches apart. Between these struts the middle en- gines are located 6 ft. 10 3/16 in. above the center line of the front wing beam. The center line of the top front wing beam is located 6 ft. 7 15/16 in. above center line of nacelle. The outer engine nacelles are centered 10 ft. 6 11/16 in. from the middle of the machine, and 5 ft. 5 1/16 in. above the top of the front wing beam. The center engines are located 2 ft. in. higher than the outer engines. The span of the upper plane not including the aileron extensions is 114 ft. Ailerons on the upper plane are 36 ft. long. Chord 43 in. At the balanced portion the chord is 6 ft. 1 in. Balanced portion extends 6 ft. beyond the end of upper rear main wing beam. Ends of ailerons project 15 ft. beyond lower plane. Chord of main planes 12 ft. Forward main wing beam centered 16 ] /i in. from leading edge; beams center 84 in. apart; trailing edge 43 1 /-; in. from center of rear beam. Hull The hull or boat proper is 44 ft. 8% in. long by 10 feet beam. The bottom is a double plank Vee with a single step, somewhat similar in form to the standard N'avy pontoon for smaller seaplanes. Five bulkheads divide the hull into six watertight compartments, with watertight doors in a wing passage for access. The forward com- partment has a cockpit for the lookout and navigator. In the next compartment are seated side by side the principal pilot, or aviator, and his assistant. Next comes a com- partment for the members of the crew off watch to rest or sleep. After this are two compartments containing the gasoline tanks (where a mechanician is in attendance) and finally a space for the radio man and his apparatus. The minimum crew consists of five men, but normally a relief crew could be carried in addition. The hull is designed to have an easy flaring bow so that it can be driven through a seaway to get up the speed necessary to take the air and a strong Vee bottom to cushion the shock of landing on the water. The combination of great strengtli to stand rough water with the light weight required was a delicate compromise, and it is believed that a remarkable. result has been ob- tained in this design. The bare hull, as completed by the yacht builder and ready for installation of equipment, weighs only 2800 Ibs., yet the displacement is 28,000 Ibs., or one-tenth of a pound of boat per pound of displace- MULTI-MOTORED . \KKO1M..\\K Tin- Nl I, transatlantic t\ |ie seaplane, powered liy four l.ilierly motors m< nt. Tliis lightness of construction was attained liy :i car, III! selection ;ili(l distribution of mat, rials. Tin- keel is of Sitka spruce, as is tin- planking. Longi- tudinal strength is thru liy two girders cif spruce braced with sti-t-1 wire. To insure w ater tightness and yet keep tin- planking Ihin. linn is a layer of muslin set in marine between the two piles of planking. The Hull is H ft. S-, in. in 01, rail length. Step is loeated _'T ft. 8 :! , in. from the bow. The stern rises in a straight line from the step in a total height of H ' _. in. The hull has a maximum depth of 7 ft. 5"^ in., and a maximum width of 10 ft. The leading edge of upper main plane is located 18 ft. 2 in. from the bow. Tail Group The biplane tail is carried on three hollow spruce nut- Front beam of upper horizontal stabilizer is MO ft. I I ' | in. from trailing edge of main plane. Gap be- tail planes. ;i ft. 3 in. The single lower outrigger from the hull to the lower stabilizer is attached to the stahili/.i r at a point 10 ft. 11 in. above the lowest point the hull. Span of upper elevator. .'17 ft. 11 in. The lower sta- bili/.er is 32 ft. in span. Knds of upper elevator project 5 ft. I 1 ' L . in. beyond the lower stabilizer. The balanced portion of tile elevators is (i ft. ~> ill. in width. Tin- upper stabilizer is :t I ft. in span. I.ower stabilizer in span. Chord of both stabilizers .5 ft. 6 in. Vertical tins between stabilizer planes are loeated at ends of lower stabilizer. From these tins, rudders are Wnged, interconnected to balanced rudder situated at the middle of tail plane. The tail planes have a positive incidence angle of 2. Controls The steering and control in the air are arranged in principle exactly as in a small aeroplane, but it was not ;s\- problem to arrange that this 1 1-ton boat could be handled with ease by one man. To obtain easy opera- tion, each control surface was balanced in accordance with expi rim, nts made in a wind tunnel on a scale model. The operating cables were run through ball Ix'aring pulleys, and all avoidable friction eliminated. Finally, the entire craft was so balanced that the center of gravity of all weights came at the resultant center of lift of all lifting surfaces and at the tail surfaces so adjusted that the ma- chine would be inherently stable in flight. As a result, the boat will fly herself and will continue on her course without the constant attention of the pilot. When he wishes to change course, however, a slight movement of the controls is .sufficient to swing the boat promptly. There is provision, however, for an assistant to the pilot to relieve him in rough air if he becomes fatigued or wishes to leave his post to move about the boat. Engines The four Liberty engines which drive the boat are mounted between the wings. At MM) brake h.p. per engine, the maximum power is 1600 h.p.. or with the full load of 28,000 pounds, 17.3 pounds carried per h.p. One en- gine is mounted with a tractor pro|-ller on each side of the center line, and on the center line the two remaining engines are mounted in tandem, or one behind the other. The front engine has a tractor propeller and the rear engine a pusher propeller. This arrangement of engines is novel and has the advantage of concentrating weights near the center of the boat so that it can be manoeuvred more easily in the air. A feature that is new in this boat is the use of welded aluminum tanks for gasoline. There are nine v2O()-gallon tanks made of sheet aluminum with welded seams. F.ach tank weighs but 7S. The Caproni Bombing Triplane Type CA-4 The ( aproni triplanc represents n type designed and built by the famous Italian constructor since 1915. This iii.-tchine was err atcd at th.it time for the night bombing of important military and naval bases, railroad stations and war plants. There are three motors, distributed on the two fuse lages and on the central nacelle. The central motor is tor a pusher propeller, while the two lateral motors have i i. li a tractor. Both tractors turn in the same direction. Fuselages and nacelle are attached to the spars of the middle wing. The center wing section, lower plane, holds the bomb rack. This bomb-dropping apparatus was also devised by Kngineer Caproni. Normally the crew of the maehine consists of two pi- lot,, seated side by side, as it is usual with the Caproni bombing planes, a gunner in the front nacelle cock pit. who operates a 1 ' ..-inch gun and two Fiat machine guns, coupled on the same mount. The front gunner also oper- ates a searchlight of the Sautter-Marie type. The rear defence is entrusted to two gunners, each of whom is seated in one of the fuselages; they also handle Fiat ma- chine guns coupled on the same mount. F.ach of the five men can move from one part of the maehine to another. Between the central naeelle and the fuselages on the middle wing a passage covered with r wood is installed for this purpose. The bomb sight and the five handles controlling the bomb rack are operated by the pilot on the right-hand si at. The CA-l triplanc has been successively equipped with three different ty|'s of motors. At first three Isotta- Fraschini 8-cylinder (vertical) 2-10/250 h.p. engines were used; it was later equipped with three Fiat A 14-Bis 6- cylinder (vertical) engines, and finally three Libcrty-12 engines. Navy ty|x- (low compression) were adopted. With an aggregated useful military load of OOOO Ibg. the performance of this triplanc, equipped with Liberty engines, have IN-CII. especially in climbing, considerably better than those obtained with the other two types of motors. In the official tests, at full load and fully armed. a speed of 98 ni.p.h., registered at 65fiO feet, was reached. The average rates of climbing attained with Liberty mo- tors at full military loads were: frrt in li minutes 6,560 fret in II minutes 10,000 fret in .'. minutes The ceiling is at about 16,000 feet. The total weight of the machine, empty, is 11,100 Ibs. With full military load the machine weighs 17,7ml Ibs. With a complete fuel load of 550 gallons, the bomb rack is supposed to be loaded with 2500 Ibs. of bombs. but practically in almost all bombing raids the load of bombs exceeded SOOO Ibs. The following is a table of the general specifications. General Eimensions Overall wing span at trailing (edge) ........... 96 ft. 6 in. Overall height to top of aileron, lever in nornml position ..................................... 20 ft. 8 in. Overall length ................................. *-' ft. II in. Chord ......................................... 6 ft 11% In. TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A Caproni 3-motored Biplane in flight. The central pusher propeller, and the tail construction can readily be seen. Span, 76 ft. 9 in. Chord, 9 ft. Gap, 8 ft. 9 in. Over-all height, 14 ft. 9 in. Over-all length, 40 ft. 9 in. Engines, 3 Liberty 400 h.p. Gap 7 ft. 13i/ 2 in. Main Planes Gap -r- Chord . ach of t , )e three p j anes ig bu0t up in seyen wing sec . Areas tions. The corresponding sections in upper, middle and EACH lower wings are equal in length. The wing spars are of SECTIOX ToT 'Y' box beam section. The ribs, double ribs and box ribs are Upper, middle and lower center section '1.413 U5.240 in white-wood and ash (cap-strip). Between rib and rib Upper, middle and lower inner intermediate the wing spars are wrapped with strong linen. The con- section 91.589 549.534 nection between the two subsequent sections is obtained Upper, middle and lower outer intermediate w j t ], t ] le ma l e an d f ema le box-fitting system. section 91.589 549.534 m, , . . ,. . . . . ,. .. . ~ -. The chord is. for the entire length of the wings. 6 ft. Upper, middle and lower outer section 130.282 781.692 Aileron area 37.810 226.863 J 1 % m. The covering is of linen, nailed on the rib cap- strips and on the leading and trailing edges. On the Total area 2,222.86: linen, above and below the wing, maple batten strips are Rudder 26.943 80.829 screwed in correspondence to the ribs. Stabilizer 109.752 . Elevator 81.614 * or tne mterplane struts, ash, spruce and seamless steel tubes are used. Some of the struts have adjustable ends. Detailed Dimensions The bracing is, as usual, with steel cables and wires. Upper, middle and lower center section length . . 5 ft. 6% 4 in. Gasoline System Upper, middle and lower inner intermediate section length 13 ft. iy lfl in. The gasoline is supplied by three tanks disposed ; two, Upper, middle and lower outer intermediate sec- one in each of the fuselages and one in the nacelle. Three tion length 1 f t. 1% in. wind-driven centrifugal pumps pump the gasoline from Upper, middle and lower outer section length. Wft % in. ^ ^ to & ^^ ^.^r, and from this to the Aileron ... ! 19 ft. 4i$ 8 to. carburetors of the three motors. The pilots have close Stabilizer length .34 ft. li% 2 in. at hand the devices necessary for the regulation of the Stabilizer breadth 3 ft. 12%,j in. gasoline pressure. For the testing of the motors on the Elevator length J Mil 8U? i g roun d two small gravity tanks are provided; these are Elevator breadth .. 1ft. l%\n. ' excluded from the circuit while the machine is in flight. Front strut height (average) 7 ft. 3^' fl in. Each of the three tanks is divided in three compartments. Rear strut height (average) 7 ft. 8i% 2 in. a nd at the bottom of each of said compartments a check valve is applied, this valve working so as to avoid that in the event one of the compartments is shelled -the gnso- ctT-r wing , c '7 d / I I de - S0 min ' line in the undamaged compartments should leak through Stabilizer chord minimum 3 deg. , , , Stabilizer chord-maximum 8 deg. the hole bored m the damaged one. Motor inclination 2 deg. Chassis Stagger deg. Sweepback deg. The landing gear is of a special Caproni design and Dihedral deg. very robust. The two M-struts are of laminated ash and MULTI-MOTORED .\KKOIM..\NKS A (':i|ir<>iii hyilroaeroplime cquip|tcil with three l-'int imitors of :K> h.|>. mch. spruce, wrapped with strong cam -is f ihrie. The chassis carries on r-irh side one front .-mil on<- rear a\le; these avlcs nre attached to the rh.-i-.sis by means of shock ab- sorlx-r rulilii-r curd .-mil rods fastened at the other end in n universal joint, so as to adsorb whatever oscillation the maehine IM.IV make in taxing or landing. Kach of the front axles carries two double wheels, one on each side of the M strut. The chassis is braced in the usual man- ner with double steel cables. Nacelle Tin- nacelle is perfectly streamlined (dirigible form). Two main longerons with compression steel tube struts bet u i en them and diagonal steel brace wire and cables form the frame on which a set of ribs of appropriate de- sign are fastened. The outer edge of the rilis determine the shape of the nacelle. Hirch veneer and walnut are employed in the construction of these ribs, said construc- tion In -ing of a manner similar to that employed for .similar elements of rtyin^ bo-its. The front of the nacelle, upper part, is formed by :i cowling made of plywood with in- terposed layers of fabric. The two pilots are seated back of the front gunner. 1'chind, they h.ive a gasoline tank, and before them a large dasbl-o-ird for the instruments, while between them thev have board for the controls i gas. spnrk and altitude ad- justage) for the three engines. The gasoline system i controlled by various cocks and a special distributor, all disposed in such a manner as to render them easily acces- sible to either of pilots. In the rear of the gas tank, which is of the same circular section that the nacelle has in that tract, there is a short path that allows the mechanic free access to the rear motor. The engine bed in con- veniently braced with adjustable steel tubes and steel braces. The rear part of the nacelle around the engine is also cowled. For the remaining parts linen and veneer are used. Fuselages The fuselages are flat-sided and of the usual construc- tion with four ash longerons, and between them compres- sion struts, steel cables and wire bracing. All the fittings, to which the diagonals are fastened, can be manufactured with the same set of dies. They are extremely simple and light in weight, without welding or bracing, and are attached without drilling the longerons. The front end of the fuselage around the motor is aluminum cowled. A gas tank is placed in the rear of the motor, and an oil tank under it. At a short distance from the trailing edge of the middle wing a seat for the rear gunner, with the The Ameriran-maile Caproni, equipped with three l.iherly motors 40 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A Caproni hydroaeroplane equipped with three Fiat A. -1-2 motors rated at 300 h.p. eaeh. The Caproni Biplane has also been suc- cessfully used in naval work. For this purpose twin pontoons have been fitted to the lower plane, with suitable attaching braces. usual arrangement for machine guns and ammunition, is installed. From the height of the gunner's seat to the rear end the fuselages are linen covered. A Pensuti tail skid with shock absorber is at the end of each fuselage. Control Surfaces As on all Caproni bombing planes, the stabilizer, ele- vator, rudders and ailerons are of steel tubes. The tail surfaces are very ample, as can be observed from the di- mensions given. The stabilizer is solidly braced to the fuselage by means of cables and steel tube struts. It bears the three characteristic vertical rudders. The ailer- ons are six in number, one at each of the ends of the three wings. As also on the other Caproni bombers, dual control is fitted so that the plane can be controlled by either pilot at will. The control system for ailerons and elevator is a combination of the wheel and stick method; the vertical rudders are controlled by a foot bar of the usual type. For emergency use, the pilot on the left also operates a hand pump, sufficient to feed the three motors by pump- ing from the central tank. Each motor has its own oil tank and a small radiator for the cooling of the oil. The lateral motors have a nose radiator, fastened on the same beams forming the engine bed. The central mo- tor has two radiators, high, narrow and streamlined, each placed at the two rear interplane struts between the cen- ter wing sections, middle and upper plane. All the ra- diators are of the honeycomb type, and equipped with shutters. Lighting and Heating The lighting systems for navigation, signalling and landing, and the heating system for the crew are fed by a wind-driven generator of one kilowatt, combined with a large storage battery. Instruments The instruments are all set in a large dashboard in front of the pilots. Besides the usual standard instru- ments for navigation, motor and radiator control, each pilot has a Pensuti Air Speed Indicator. Some machines are also equipped with an Absolute Speed Indicator. CAP12ON1 Left One of the two tail skids. The skid itself is of ash, wrapped with linen and shod with a metal shoe. Right- One of the two landing chassis units, composed of four wheels with double rims and double tires. MULTI-MOTORED . \KKori..\NKS II , \ pcll.-rs Hi'- hull has a (in ami two steps. This Up,- of boat was much used for patrol duly. Curtiss H-16-A Flying Boat Tin II -Mi A is :i t in-i-iiiiiin-d M-aplaiic with a flying- l>oat hull, usin^ trai-tor propellers. The pilot and ob- scner .-in- seated in a cockpit about half-way ln-twrrn the linw mil tin- winjjs. where they have an e\ei Hi lit view. The 11 li! is also fitted with a gunner's cockpit the same as tin IIS :. In addition, a wirrlrss opi-rator is rarricd "nside the hull just forward of the wings and hark of tin- pilots. Ali-ilt tin- winiis an additional nun ring is fitted COM rim; tin arc of tin- al'ovr and between tlie wings and tin- tail controls and to take care of the region to the rear- and l low tin- tail .-ontrols; gun mounts are also fitted. swinjiini: i\ brackets through side doors in the hull. The hoinh near is opi-ratrd from the forward gunner's eoekpit and four lioinli-. wi-n- rarrii-d. two under either wing. This typi- of boat proved very MTV in-able. General Dimensions Win? S))n I'pprr Plum- 98 ft. 6% in. ^|>.in - l.owrr I'lnnr 68 ft. 11% in. Di-ptli ..f \V in); Chonl 84<%4 In. ti.-ip iM'twrrn XVinjr- Sfi^ili In. .. r Nun.- ,,f Mm-hini- ovrrull 46 ft. l%o in. M.-i-lit of MarliiiH- overall 17 ft. 8% in. i- of Incidence 4 dejrrees Dihrilnil Anfflr 1 degree luu-k None \Vint' Curv R. A. F. No. 6 lli.ri/.Mital -it.'iliilixer Anple of Incldenrr ... 2 degrees pos. Areas I'pper (without Ailrrons) 616.2 sq. ft. I.i wrr 4-13.1 sq. ft. .is 131 sq. ft. Horizontal -ital.iliwr 108 sq.ft. Vertical St il.iliier 31.1 sq. ft or- 58.4 sq. ft. Kudili r J7.9 sq. ft. nl* ?4 sq. ft. Totnl Sui)|H)rnii)f Surface 1.190J sq. ft. (welfrht carried per MJ. ft. of support- 8.S4 lb. in|r surfaci-) Londinir (per H. H. I'.) 15.42 Ihs. Weights Net Wei(rht Mnrhine Kinpty i;.'i:,i; ll.s. Cross Wright Mnrhine nnn(! Ihs. Fuel and oil I^.T Ihs. Crew i Ihs. load . . 1.029 Ihs. Totnl :Wlfi Ihg. Performance Speed Minimum Horizontal Klipht 9.5 miles per hour Sprnl Minimum Horizontal Kli(rht j.i miles per hour Climhin)! S|M-1 I.OOO fret In 10 minutes Motors 2 Liberty- 1-' cylinder. Vre. Four-Stroke Cycle Water cooled Horse I'nwer (rarh motor IMO) 660 Weight per rated I lorsc I'ower 2,55 Bore and Stroke 5x7 in. Furl Consumption pi-r birr (loth motors) 62.8 gals. Fuel Tank Capacity 300 gals. Oil Capacity Provided 10 gals. Fi-l Consumption per Brake Hnrsi- I'ower per 0.57 Ibs. Hour Oil Consumption per Brake Horse Power per 0.03 Ibs. Hour Propeller Material Diameter, according to requirements of performance. Pitch, according to requirements of performance. Maximum Range At economic speed, about 875 miles. 42 MILTI-MOTOKK1) .\KKOPI..\\KS I . I N from >' | In lin . hours. In iiml'.K-tiire. ng Bout, equipped uitli two Liberty inuturs. It ca n. and li.is a cruising railins of Throughout, I In- \arious p.irt re so designed that efficient priMluction methods ean ! used in its F-5-L Navy Flying Boat Tin- II I lying Moat is a twin-motored tractor bi- plane, ha \ing n total Hyinn weight nf lu-arly 7 tons, a cruising radius of ]iil._. hours as a tighter, or S 1 - hours as -i liiiiiilu-r. It carries a military load of over I KM) Ibs., with -i crew of four mm. It is so designed that it may l)r ijiiii-kly .-Hid efficiently built. Tin- I ' ." I is i somewhat larger machine than either the II-l-J or the H-l(i and is capable of carrying a greater useful load. I Mini urn iit.illy the plnnc is similar to our American Curtiss Hying bouts particularly the H-1G model. Hut in si/e .'11111 details it is quite different, being larger and better titled to emergency production. For example, with \eeptinns the fittings are soft sheet steel, cut from Hat patterns and bent to shape. This obviated the necessity of dies and drop forcings, which are particularly difficult to obtain under war condi- tions. The struts, likewise, are uniform sections, that is, not tapered, so that they can be shaped with a minimum of hand labor. Throughout, the parts are such that du- plication is easy, production methods possible, and read- ily available equipment suitable. The specifications herewith will give some idea of the si/, mil eapaeity of this seaplane. It will be noted that the lift per square foot of surface is from 9.3 to 9.") Ibs. ,uare foot and is somewhat greater than land prac- The I-' -.1-1. is the latest development of the boat type seaplane, having the tail surfaces carried on the fuselage construction and the fuselage entering into the hull of the boat. The Curtis, boat seaplane may be i sidcrcd a forerunner of this type. The characteristics nre a fuse- lage similar to that of a land machine, planked in to form a boat body and having planes or steps similar to a hydro- plane at the forward end. Sl'l.c II If VI IciNS OK \.\VY F-5-L FLYING IK i \ I Overall upper wing (including ailerons) 103 ft. 9% In. Overall lower win* 7 ft. I in. Overall li-ii(rtli of lin.it 49 ft. 311,,, in. Overall heijflit of boat 1H ft. 91 4 ' in. \Vimr chonl (II-IJ curve) H ft. Cup iM-twren upper and lower panels C. I.. brams.H ft. 10% In. Antflr <>f incidence of wlnjrs plus 3 drg. 4<) mln. Dihedral of winjf 1 ' . d. ir Stagger of win);* Nnne Angle of incidence horizontal stab, plus iy t deg. F.ngine sect, panel 10H sq. ft. liili-nn. and upper outer panels (31 1 s<). ft. each) 611 sq. ft. A il.-nins (.',!) sq. ft. each) 11H q. ft. Sidewalks (: s<|. ft. each) 66 sq. ft. Ixiwer wings (.'Ml sq. ft. each) - Nun-skid planes ( l.i si|. ft. each) 3i- * << one pilot and two or three gunner*, and an observer who operates the bomb- dropping devices. Their placing is ns follows: At the Areas forward end of the fuselage is the gunner who operates a Si/nor* ii.iir of flexible Lewis machine guns. Bowden cables at .... , , , , T, I pper plane with ailerons lOlH one side of the cockpit permit the release of bombs. Be- y^WJM (2) each Hi lun.l th< -gunner is the pilot's cockpit from which the gun- | x)Wer p | ane 630 ner's cockpit is reached through an opening in the bulkhead Total wing area with ailerons 1648 separating the two compartments. The pilot is seated at I'pper stabilizer th. right side of the cockpit. Beside him is the observer's {^*" to ^ ah ( "'j"' r ^0 seat, hinged so it may be raised so as to permit access. j.. jn H 7 Bomb-releasing controls are placed on the left side of the Rudders (3) 46 observer extending to the forward gunner's compartment and running back to the bomb racks located in the fuselage Weights, General Pound , just between the wings. Machine empty 1466* Forward compartments are reached via a triangular FueJ am j () j| 3496 door on the under side of the fuselage. Bomhs So* Aft of the bomb rack compartment, the rear gunners Military I-oad . are placed. Two guns are located at the top of the fusel- **?*, ' 1 1 ; ; '. ; \ ] \ \ \ \ \ \ \ ] \ \ \ \ \ [ \ [ \ \ \ \ \ * M age and a third is arranged to fire through an opening in Weignt per h orM . pawn 175 the under side of the fuselage. One gunner may have charge of all the rear guns, although usually two gunners Summation of Weights man them. A platform is situated half way between upper Power Plant . . . and lower longerons of the fuselage, upon which the gun- fjjjj^ am j 'n,,^,,,,,^' ^uip^nt '^i '.! ! ! i!" !! 610 ner stands when operating the upper guns. Armament 3* Machines of this type can be utilized for commercial Bombing equipment 3000 aerial transportation, and are capable of carrying loads Body structure . which would enable them to efficiently perform this func- Tall ""^^^ '"' ^^^ tion. By leaving off the various military fixtures, the use- ch j) u 710 fill carrying capacity, for passengers or freight, will be greatly increased. Total 48 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING WEIGHT SCHEDULE Power Plant Engin.e complete with carburetor and ignition system J x 835 = Radiator 2 x 112 = Hadiators and engine water -2 x 150 = Fuel tank empty and pipes Oil tank empty and pipes 16x2= Exhaust manifolds -2 x 7.5 = Propeller and propeller hubs 3 \ GO = Cowling -2 x 100 = rounds 1688 994 300 350 32 150 190 200 Volumes Bomb section, 3 ft. 5% in. x 5 ft. 2 15/16 in.x4 ft. 5 in. Hear gunner's platform (upper) 3 ft. 3'/ 8 in. x 5 ft. 1% in. x 4 ft. -"/, in Hear gunner's platform (lower) 2 ft. 4. in. x 5 ft. 1% in. x 4 ft. ->'/, in Cu. Ft. 80.6 71.45 54.2 Total volume 200.25 Total Height (Feet) . 5,000 . 7,000 Performances Speed Time of Climb (M.l'.ll.) (Minutes) . . . 92 . . . 90 12 18 Fuel and Oil 10,000 85 32 Fuel (280 gallons) 2280 Oil (2x 15.3 gallons 2x 108 ll,s.) =J18 Planes are not swept back and have no stagger nor Total -196 decalage. Beyond the engine nacelles, both upper and Passengers and Equipment l wer P lanes have a dihedral angle of 4 degrees. Pilot and clothing 170 ^'ing section employed, R. A. F. No. 6. Angle of lower Gunners and clothing 340 wing chord to propeller axis, 3 degrees. Dashboard instruments, fire extinguisher, tools and Aspect ratio of upper wing, 10; lower wing, 7. ma P s Planes are in nine sections. Upper plane center section Total gjO 16 ft. in. wide. Intermediate sections 22 ft. in. wide; overhang sections 16 ft. 10 in. wide. Beyond this, the Armament ailerons project for a distance of 3 ft. 2 in. Two forward machine guns, mounting and ejection am- Lower , ne jn four sections . two between fuselage and munition and sights 12X) Three rear machine guns, mounting and ejection am- en g' ne nacelles and two outer sections. munition and sights 180 Interplane struts spaced as follows : nacelle struts 8 ft. in. from center of body; intermediate struts 10 ft. in. Total from nacelle struts ; outer struts 1 2 ft. in. from inter- Bombing Equipment mediate struts. Overhang rods anchored 14 ft. in. from Bombs 2500 outer struts. Overhang beyond bracing 6 ft. in., includ- Bomb releases and sights 500 j n g ailerons. Ailerons are 20 ft. 7% i n - 5 n ; 3 ft. 9 in. in chord. i otal oOOO Overhang portion 3 ft. lyj in. wide. Body The accompanying drawing illustrates the manner in Body frame 953 + 97 = whieh the main planes are hinged aft o f the eng j ne n a- Front control' and rear control' !!!!!! i!/!! !'" !!!!"!! 100 celles ' Permitting the wings to be folded back so as to fa- cilitate housing in a comparatively narrow hangar. In Total 1210 folded position the measurement from leading edge of Tail Surfaces with Bracing wi ? * centerl ' ne of fusela g e is 15 ft - 6 in - ,_ For bracing between planes, oval section steel rods are Stabilizers (no covering) 3 57.2 Elevators (no covering) 4 34.4 used exclusively. Jinds are formed to a solid section Fin (no covering) 1 6.4 which is threaded and fitted with a trunnion barrel and Rudder (no covering) 2 28.8 forked terminals. Covering 35.4 _ . Struts and wires , 24.4 The fuselage is built up with the usual longerons and Total 187. cross members. Bracing is with solid wires with swaged Wing Structure or forked ends ' Upper wing with fittings, aileron and fuel tank in center Total len g th of fuselage, 62 ft. 10% in.; maximum section; lower wing with fittings 2032 width at tile wings, 4 ft. 9 in., tapering in straight lines to Interplane struts 235.5 2 ft. 11 in. wide at the stern ; maximum height, 6 ft. 10 in. Interplane cables ... 261 j n fl ving position the top longerons are horizontal to the Nacelle supports 2 x 105 = 210 " ,, , , ,. . propeller axes; top longerons 12 ft. 3 in. above ground. Xotal 2738.5 Leading edge of planes 1 2 ft. 2 in. aft of fuselage nose. Chassis Tail Group Wheels complete, 2 x 170 = 340 The tail is of the biplane type with a gap of 6 ft. in. Shock absorber, 4 Average chord, 8 ft. 6 17/32 in. Chord, above bodv, 5 ft. Miscellaneous parts, 4 x 30 == 120 _ ,' ' Tail skid 50 ln ' ^pan f stabilizers, 16 ft. 7y-> in. There are two pairs of elevators 1 ft. 10 15/32 in. wide Total 710 and 8 ft. 5 J X> in. long. MII.TI-.MOTOKKI) AKKOIM..XM- - M The iiu; rim-triirtion of tin- lliiinllc\-l'.ij:e machine-. Struts fruiii hotly to top t.-iil plane spaced 2 ft. !' t in. from renter to center. From these, tlir outrr forward struts and rudders are spaced i> ft. :>' in. Central M rtical tin, I ft. () in. wide. Rudders are balanced. Width t ft. HI' -in. Control failles run to their tr.-iilini; > ili:< >. and a MBpeBMtfag cable runs through the fin from the leading edge of one rudder to the Icadiiii: cdae of the other. Landing Gear The landing gear comprises four 2 ft. 11 7/16 in. dinm- cter wheels with tires 7^ j,, wide. Wheels arranged in tun |i i;r- < :ieh pair h.-iving a 4 ft. 6 in. tread, and inner wheels spaced 5 ft. Sfo in. from center to center. .\\le-, -in Imiu" il at center. Vertical shock absorber iiiecli.-inisiii enclosed in /in aluminum casing. Tail skid is the usual swivelled pylon-mounted ash skid, shod with a sheet steel plate. Engines Tin- Liberty engines are entirely enclosed in streamlined sheet aluminum nacelles between the planes. Propeller axes 10 ft. Ill 16 in. above ground when machine is in Hying position. MANDLEY-PAGE ((Mr Hi' till' four shock ;lli sorlx-r units nf the IUmll<-\ Pafrr ItmulH-r. The stream- line sliet-t .iliniiimiMi en-iriu' is rrmoxetl til sliow the nirth IM) nf -trin^illj.' the rlasti<' cnril tH-twt ell v.nlilles llttlicheil tn tin- I i \i-il linicr MI ii I the .slidini.' rinls res|iecti\fl\. Propellers 10 ft. 6 in. diameter. Imth revolving in the same direction. Kadiator faces have adju.stnhle shutters to regulate tin- air admittance. Water capacity of radiators, ,S(M) Ibs. Each of the two Liberty " 1-J " engines gives -KM) h.p. at 1.625 r p.m. More and stroke 5x~ inches. I in I ton sumption, ..95 Ibs. per h.p. hour; oil, .03 Ibs. per h.p. hour. Engine weight, M, (Ht Ibs. with propeller. Tanks located above bomb compartment. Fuel capac- ity, 280 gallons; oil, 15.3 gallons. Thr transatlantic type. British make. Handle) -Pap- biplane, powered with four Rolls-Kojcc motors 50 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The J. V. Martin Cruising Bomber. One of the very original machines developed in this country by Captain James V. Martin for the U. S. Army. Two Liberty "1-3" engines, located within the fuselage, drive two four-bladed tractor screws by means of bevel gears. This machine has the Martin automatic wing-end ailerons, K-bar interplane struts and other un- usual mechanical constructional features. The Martin Cruising Bomber The Martin Cruising Bomber is equipped with two en- gines located in the fuselage and driving two tractor pro- pellers by means of bevel gear transmission. Since either engine will drive both propellers, the failure of one of the engines does not impair the efficiency of the plane. Either two Sunbeam 300 h.p will drive the plane at 74 m.p.h., or two Liberty 400 h.p. engines will drive plane at 81 m.p.h.; in either case with a two ton useful load. Fully loaded the machine can make a.speed of 110 miles an hour. The useful load is three tons not including one ton of fuel and oil. The K-bar cellule truss is used, which eliminates half of the cellule structural resistance due to wires transverse to the line of flight. The machine is also provided with the Martin retract- able landing chassis, which has been found to be strong, light and reliable. It eliminates 14 per cent of the struc- tural resistance of the Bomber. Mr. Martin claims that safety and dependability are increased because of independent transmission support, for the propeller breakage will not endanger cellule truss, and because cellule stresses are low and are more ac- curately calculable. As the engines are enclosed, resistance is no greater than where a single engine is used. Such placing makes the engines accessible for minor repairs and adjustments. View of the power plant of the J. V. Martin Cruising Bomber. A view of the Martin Blue Bird in flight. This small machine has the K-bar truss and retractable landing gear, as does the Martin Bomber described above. Mn/n-MOTOHKI) AKKOl'I.AM.S 51 Tin Martin Twin l.ilx-rtv Motored Bomber. Glenn L. Martin Bomber The Martin bomber is a machine of excellent perform- ance, as show n in its official trials. An official high speed at the ground of 11H.."> m.p.li. was made on the first trials, with t ill bomhiin: load on l>oard. This speed lias been bettered since, due to the l>etter propeller efficiency arrived at by e\pi-nsj\e experiments. With full bomb load, the cliinhinir time to III.OIMI ft. was I ,"i niin.. and a service ccilini: of between lii.oiin and I7.OIM1 ft. was attained. As i militarv in.-ieliiiie. the Martin Twin is built to ful- fill tin rci|uircnicnts of the four following classes: (1) night bomber: (2) day bomber; (3) long distance photog- raphy; ( 1) gun machine. \- i night bomber it is armed with three flexible I w is machine guns, one mounted on the front turret, one on the re.-ir turret, and the third inside the body, and firing to the rear, liclow and to the sides, under the concave lower surface of the body. It carries l.'.(M) pounds of bombs and looo rounds of ammunition. A radio tele- phone s, t and the necessary instruments are carried on all four types. The fuel capacity in all four types is suffi- cient for one-half hour full power at the ground and six hours' full power at 1 .1,000 feet, and enough more for about six hundred miles. As a day bomber two more Lewis guns are carried, one more on each turret. The bomb capacity is cut to !bs. to give the higher ceiling necessary for day- work. (3) When equipped as a photography machine, the same number of guns as in the case of the day bomber are carried ; but in plaee of the bombs two cameras are mounted in the rear gunner's cockpit. One camera is a short focal length semi-automatic, and the other is a long focal length hand-operated type. The gun machine is equipped for the purpose of breaking up enemy formations. In addition to the five machine guns and their ammunition as carried on the photographic machine, a semi-flexible 37 mm. cannon is mounted in the front gun cockpit, firing forward, and with m fairly wide range in elevation and azimuth. This can- non fires either shell or shot, and is a formidable weapon. The Martin Twin is easily adaptable to tin- commercial uses that are now practical. They are: (1) mail and express carrying; ( ' ) transportation of passengers; ( :( ) aerial map and .survey work. (1) As a mail or express machine, a ton may be carried with comfort not only because of the ability of the machine to efficiently handle the load, but because generous bulk stowage room is available. (2) Twelve passengers, ill addition to the pilot and mechanic, can be carried for non-stop runs up to six hun- dred miles. (S) The photographic machine, as developed for war purposes, is at once adaptab.< to the aerial mapping of what will become the main flying routes throughout the General Dimensions and Data 1. Power Plant Two l.'-cyl. Liberty engines. i. Wing nml Control Surface Areas. Main planes (total) 1070 sq. ft I'pper planes (including ailerons 450 I.ower planes (including ailerons ) '>'<> Ailerons (each) MJ No. of ailrrnns * Vertical Fins (each) 8.8 No. of fins i Stabiliwr Hewitor M .''' Rudders (each) 16,50 Vo. of rudders 3. Overall Dimensions Span, upper and lower 71ft. 5 In. Chord, upper and lower 1 " 10 " Gap " " Length overall * " Height overall 14 " 7 " Incidence of wings with propeller axis Dihedral None Sweep back None Deealage (wings) None Stabiliser, setting with wing chord adjustable between ** normal letting 9 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING country. The accuracy that is being obtained in aerial photography should be of vast value in surveying and topographical map work. Wing Structure The wing truss is conventional outside of each of the engines. From one engine through the body to the other engine, the truss system is a very rigid but light one of streamlined steel tube tension and compression members. These members are arranged primarily with three objects in view, that is: (1) Ease of removal of the engines. (2) Rigidity throughout the landing and power system. (3) Simplicity and hence low weight and resistance. The wing spars are of the conventional spruce eye- beam type. Interplane wood struts are two-part and hollow, and they are pin connected to the wing fittings. The wing ribs are of a novel type, developed through very extensive experiments on all types. They weigh, each, eleven ounces and have a minimum factor of safety of eight. Scrap spruce is employed in their manufacture, and by the use of a clever jig, speed and accuracy in their assembly make it a fine production job. The wing fittings completely surround the beam in every case, and are designed from every minute consideration to give a factor of safety in excess of six. Double flying cables and single landing and incidence cables are used throughout. No turnbuckles are employed. A right and a left-hand threaded eye-bolt made into the cable by the conventional warp method, engage similarly threaded clevises, pinned to the fitting ears. Streamline wires are interchangeable with the cables in this system. Swaged tie rods are used throughout for the internal wing bracing. Pin joint connections tie the lower wings to the body, and are also used at all panel connections. A minimum factor of safety of six is secured throughout the wing truss for the heaviest loaded conditions. The body in many respects is the most interesting part of the airplane. At the nose is the cockpit for the front gunner, mounting at its edge the scarfed gun mount. The front gunner has access to a passageway through which he can go aft to handle the rear lower gun, or sit beside the pilot on a folding seat. The pilot is placed on the right- hand side of the body and well up so that his range of vision is the best possible. He is provided with a wheel type control and has a splendid view of the instrument board. At his right and under his seat is the hand wheel which operates the adjust- able stabilizer. Behind the pilot are the three main gaso- line tanks. The passageway and firing platform for the rear lower gun terminates at the rear wing beam station. Here, on a special mount, is the lower gun, which commands a large field of fire horizontally to the rear, below, and to both sides. This gun is operated from a prone position by either the front gunner, rear gunner, or a third man, if four are carried. The tunneling of the bottom of the body to permit the mounting of the lower gun has introduced difficulties in trussing which have satisfactorily been solved in a simple and light manner. The lower transverse strut and cross of transverse bracing wires usually found at each trans- verse section in the truss type body are replaced by two steel tubing struts. The ends of these struts are threaded right and left- handed, and engage similarly threaded forked ends which pin to the body fittings. By this means the transverse sections are squared up. In all other features the body is a combination of two standard types : the wire and strut truss, and the veneer plated wood truss. Three-ply birch or mahogany veneer is used on the body sides, at the nose and tail, and in the bulkheads employed in the body. Swaged tie rods and threaded clevises are employed throughout for truss ten- sion members. The longerons aft of the rear wing beam station are hollowed out between fitting attachment points, the degree of routing increasing with the progress to the rear. A cheap, simple and effective steel plate longeron fitting is employed at the rear body panel points, while heat-treated chrome vanadium fittings are found at the main wing truss attachment points. The tail skid is braced entirely by the internal body structure at this point. It is universally pivoted and is sprung by sturdy elastic chords inside the body to receive the landing shock. Engine Units The Liberty engine is firmly mounted in a light girder box of veneer, resting on brackets on the four main wing struts. It is so secured that engine, radiator, airscrew and nacelle may be removed intact from the wing struc- 1 One of the four landing wheels showing the streamline shock absorber casing and the wheel guard to protect the propeller from stones and mud. -2 One of the main ribs, showing sections through wing beam and leading edge. 3 Fit- ting at ends of wing struts. 4 Tail skid unit, with shock-absorber elastic removed. MlLTI-MOTOHKl) .\KHO1M..\N I - turr. A nose radiator nf tubular i-i-ll construction, weigh- ing Complete ^ ll>-.. is mounted in a unii|uc and \rr\ satisfactory iiiainn r. Two ll.iiii;. .1 steel rinys are In Id together h\ machine screws, .mil when in plan- wedge a strip of rnlilx-r firmly between (lu-in and tin laces .if the rirculiir Imlr cut in tin- radiator tor tin airscrew shaft. Thr rear ring carries platrs. which in turn liolt to plate-, secured .-it the cnil of the engine hearers. The whole weight of tin- radiator then is carried from its central hole. \o |nrt of the- nd:.itor touches am part of the mounting hut has a cushion of rul>l>er si paratmg it from the mounting and absorbing the- shock Iroiu the engine. I ich radiator is ei|iiippeil with shutters, operated nt tin- will of the pilot, for the purpose of regulating the water temperature. An expansion tank is let in to the trading portion of the upper wing above each radiator, and is connected to it. The top of (he engine is .\poscd. This aids iii cooling, of course; makes the engine more acces- sible for working o\i r. and permits the n diictioii of cowl- ing weight to minimum consistent with low head resistance. The airscrew used is the Douglas type, and is 9 ft. 8 in. diameter and li ft. 1 ill. face pitch. It is the best over- all hlade git ing a satisfactory high speed and climb at reasonable rev olutions. The three controls from each engine, carburetor, igni- tion and altitude arc positive controls, operated easily and convcnicnth bv the pilot, either in pairs or singly. An ample supply of oil is carried in a tank situated in each motor nacelle. Undercarriage The undercarriage is composed of four 800 by ISO mm. wheels. Four sets of triangulated struts carry the load from the two axles to the four main structural points of the machine. The axles are hung on the usual rubber cord suspension, but have a large amount of freedom not only vertically, but in the other two directions. All the lateral forces are taken up at the center trussing under the body. The two outside sets of struts are free to swing laterally, and hence only absorb the vertical component of the landing shock. Simplicity with extreme low weight and head resistance has in this manner I ecu secured but at no expense to the proper functioning and wear and tear n sistance of the gear. The flexibility of this arrangement absorbs all kinds of shocks in a very satisfactory manner. Controls and Control Surfaces A single wheel and foot -bar control is provided in the pilot's cockpit. The interesting point about the wheel control is that the usual weaknesses of this tyj)e have been eliminated. The aileron rabies pass over no drums, nor they hidden within tubes where wear can be detected. The dangers of the chain and sprocket aileron control, with its e\er present tendency to jam, are not encountered in this type. The IS in. wheel is keyed to a steel shaft which carries on it, within the upper gear case, an alloy steel bevel gear. This meshes with another gear keyed to a vertical torque tulic. running in ball-bearings mounted inside the control column. At the lower end, the tori|iie shaft carries a pinion which engages with a steel rack. The rack i guided inside the lower gear case, and has attached to it the dual aileron control cal h s. The whole unit is v.rv strong, rigid ami reasonably light. 1'ropcr power on tin- lateral controls is readily obtained, which in the (Base of either of the other types would m\ol\e ditiiciiltu s. e.|iial ami unbalanced nilerons are carried. These supplv the ncci ss-inh ln-li .1. -n . .>f lateral controllability required of ,-i machine of this t v pi The tail siirfans ,r. of steel and wood const ruction. It is noteworthy that the stabili/.er is adjustable from the I'll I hi , niir. tail surface structure is hinged at the rear stabilizer spar. The front truss system termi- nates in a \ertical tube, mounted in hi arings inside tin- body and threaded to engage a nut. Tables wound on a drum operated by the hand wheel at the pilot's side turn the nut and thus raise or lower the front of the stabiliser, and with it the tail surface trussing. A range in angle .>! the stabilizer of plus or minus three degrees from neutral gives the pilot n powerful means of halnncing the airplane in any flying attitude or for any load distribution. The ihvatiir is one piece, and, with its generous area and ease of operation, forms a positive control to be relied on in any emergency. Two balanced rudders, working in synchronism, permit the pilot to control his direction under any conditions with ease. In fact, when flying with one engine dead, the amount of rudder movement necessary to correct the off- setting force of the other engine is surprisingly small. It leaves an ample margin of control for maii.eim ring under these conditions. Gasoline System The gasoline system has been developed to eliminate the many troubles usually encountered from this vital part of the airplane. Three sturdy tanks, mounted securely inside the body, contain the main supply of gasoline. Two gravity tanks, mounted in the upper wing one over each engine, each hold gasoline enough for one-half hour's flight. All tanks are made from tinned steel. They are braced securely by many internal bulkheads, all scams are double lap. rolled and sweated, and all rivets used arc large headed tinned rop|>cr rivets. None of the tanks are subjected to any pressure when the system is in operation. The three main gasoline tanks drain into a combination distributing valve and sump operated from the pilot's com- partment. Any tank can be rut in or out of the line at will. I'ipes from the sump lead the gas to the two air-driven gear pumps located In-low the body. Valves, controlled by the pilot from his seat, arc provided in the pump lines. Hy means of these valves either pump may be by-passed on itself or allowed to feed gasoline to the carburetors. One pump alone is more than sufficient to feed both motors full on. Two are provided as a safety means. Leads from the pumps run out to the carburetors of both engines. A lead running from each of these main supply lines to the gravity tanks supplies them with gaso- line and serves to carry off the excess gasoline pumped by the main pump. An overflow pipi is led from each gravitv tank to the main tanks. A hand operated plunger pump is installed, and may be used to fill the gravity tanks or to supply the engines should I oth air-driven pumps fail. IO 5UNDSTEDT-HANNEVIO TWIN MOTOBtD SEAPLANE 54 MII/n-MOTOKKI) AKKOPLANKS The Sumlste.lt-H.mniM..- Seaplane equipped with two Moilrl "I I" 1 1 ,II-S. ,.tt Kn|(inev (lluilt l>\ tin- \\itteiii.iim I.rwis Airri -.<-.) The Sundstedt-Hannevig Seaplane Tin- Stffidatodt-Hannevig seaplane lias In en d, signed for tin specific purpose of long distance tlvinir over the sea. In genrrnl. it lias been designed with an extra heavy sub- stantial eiinstriietinn. partieularlv on those parts subjected to tin- iircatcst amount of strain during flight and at land- ings. Midi as pontoon-.. HJII^S. and the entire rigging. In tin desiiiti. liowi-vi-r. only proved aerodynamienl prin- ciples have been embodied, assuring a positively efficient maeliine. and ("apt. Sundstedt lias made a large number of inipro\enients in structural details, affording the utmost .strength anil lightness of construetion. Tin seaplane is equipped for two pilots and two pas- 's in the cabin of the fuselage. General Dimensions in. 6 in. in. in. .' in. 6 in. 7 in. plane ............................... 100 ft. nwer plane ................................ 71 ft. Imril. lower pl.nie ......................... 8 ft. luinl, upper plane ........................ 8 ft. '"tween w iiip. ............................. 8 ft. 'i nf i.nieliine over all ...................... 50 ft. Height of in n dine 'over all ...................... 17 ft. Dilinlr.il nnirle. lower plane .............................. 2* urvc .................................. f. S. A. No. 5 n'timr surfHee ............................. 1,537 sq. ft. Ku.lil.-r area ....................................... sq. ft. T area ...................................... 44 sq. ft. \\YitrM ........................................... 10,000 Ihs. I n.iili'iir |HT h.p ....................................... 33 Ihs. l.iwilinir per sq. ft ...................................... 6 Ibs. estimated, full load .......................... 80 m.p.h. ('liinliiiifr s|>citl, estimated ................. 3,000 ft. in 10 min. total ........................................ +40 Pontoons Tin pontoons are of special Sundstedt design, embody- ing the highest developed features of streamline and fol- low tin most accepted construction practice. They are in pi' of Capt. A. P. Lundin's special three-ply Balsa wood veneer, covered with linen, and are each divided into eight watertight compartments, painted and varnished with torpedo gray enamel. They are 32 ft. in. long, spaced 16 ft. () in. apart from centers, and are light in weight, being 400 pounds apiece, including fittings. Each pontoon is equipped with an emergeiiey food locker accessible from the deck by means of a handhole. The pontoons are braced to the fuselage and wings by a series of steel tubing struts with Halsa wood streamline fairing. These tubes are of large diameter and tit into sockets mounted on the pontoons and wing spars. The entire assembly is amply braced by steel cables and tub- ing connecting struts. Fuselage The fuselage is of streamline design, and is flat .siiled in order to provide sufficient vertical surface necessary for good directional stability. It has a curved streamline bottom and hood running fore and aft. The construction is of white ash and spruce, consisting of four longerons and ash and spruce compression struts fastened thereto with light universal steel fittings, to which are also fast- ened and connected diagonally the solid steel brace wires and turnbuckles. The front end of the fuselage is fitted up much after the style of a closed motor car, with comfortable up- holstered seats for the pilots and passengers. This cabin is accessible by a door on each side at the rear end of the cabin. A very complete field of vision is obtained through a series of glass windows around the front of the pilots' seats, forming a recess in the upper deck forward of the windows. Directly behind this cabin, and balancing with the cen- ter of pressure is the main gasoline tank, with a capacity of 750 gallons, sufficient for 22 hours of full speed flying, and to the rearward of this is the adjustable open truss- ing, with a detachable hood and covering for access and inspection. The forward section is covered with a thin three-ply mahogany veneer up to the rear of the cabin doors, and 56 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Sundstedt Aerial Cruiser being assembled. It is equipped with two Hall-Scott motors. aft of these, it is covered with linen, doped, painted and varnished. Control The control system operates on the standard wheel and rudder bar method, and is of special Sundstedt design, whereby all cables are located beneath the floor, leaving a clean control column and rudder bar without any wires in the way of the passengers or pilots. Dual control is fitted, side by side, directly connected, so that the ma- chine can be controlled by either pilot at will. All engine controls and switches are located on the dashboard, operative from both seats. Instruments A substantial dashboard is fitted in front of the pilots' seats in a plainly visible position, and is equipped with tachometers for both motors, clock, altimeter, speedometer, radiator thermometers, oil pressure gauges, shut off valves, ignition switches, and so forth, which are located within easy reach of the pilot. Power Equipment The power plant consists of two Hall-Scott Model " L-6 " h.p. engines, directly connected to two bladed pusher propellers. Each is mounted on a specially con- structed bed by the Vee method of interplane struts, with the engine beds, housings, and radiators all securely braced to the wings, pontoons and fuselage. The engines are supplied with gasoline by turbine driven Miller gasoline pumps which maintain a pressure of 3 Ibs. in a special reservoir of the pump itself, under auto- matic adjustment, and eliminating all of the difficulties and dangers of the gravity and pressure feed systems. These pumps are regulated from the cabin and within easy reach of the pilots. Wings The wings are built up of five sections in the top plane and three in the lower. The center section of both the upper and lower planes are 18 ft. 10 in. long, and so de- signed that the pontoons, the power plant, and the fuse- lage can all be assembled completely before adding the remaining outer wing sections, thereby taking up a mini- mum amount of space in assembly during manufacture. The main spars are of laminated built up section, serv- ing to give a very high strength and exceptionally light construction of a combined I-beam and a box beam section. The upper wing has a chord of 10 ft. in. at near the junction to the center section, and narrows down to 8 ft. 6 in. at the inside of the aileron cutout. Of this, 8 ft. in. is well constructed web form of rib, while beyond this distance the cap-strips are run out with a small piece of spruce between, serving as a very flexible trailing edge, greatly increasing the stability and gliding efficiency of the machine. The underside of fuselage showing control connections on the Sundstedt-Hannevig Seaplane. It is covered by an alumi- num cowling. MII.TI MOTOKKI) .\KltoiM..\\KS other strains on the wings, and subjecting the wing ribs to the one purpose of lift only. The wing seetion used in the I'. S. A. No. .'>, whieli is especially designed f or |,J K |, S J M .,.,I nm j Kn . at | if , Sl . rv j ng as a medium between a scout and an extra heavy lifting wing, and, as well, lias high structural safety factors. The iiiterplane struts are nil made of seamless steel round tubing, streamlined with Halsa wood encased in linen, and the struts with reinforced ends are fitted into sockets which are bolted to the main spars of the wings l>y tour nicklc steel bolts straddling the wing spar to tie plates on the opposite side of the spar. The lower plain- is entirely constructed of solid rilis. with a chord of S ft. () in. The wing ribs are cut out of a spe.-ial thro ply x. n< , r. with lipped end-., ti t ting closely into the boxes of the I-beams, and fastened in place bv means of two cap straps, glued, nailed and screwed to the webs and wing spars. At the points of fastening the iiiterplane struts to the main spars of the wind's, there is an internal steel com pression tube, reinforced at the ends, bolted in place, and .socket, fastened directly to the main spars, mtcrhraccd diagonally with solid steel wires fitted with turnbuckles for adjustment and locked, taking up all of the drift and ** i | Thr Kennedy " Ciant " Xeroplnne, equipped with I S.ilmsmi eriirfiies of .W h.p. each. Span. U.' ft.: length, HO ft.; height, in.; chord. II) ft.; gap. IO ft.; total weight, Ifl.lKK) ll.s. empty. Ttiis mnrhinr was ahamlonrcl in 1!U7, hut th- results !,- iniil with it h-ne l.e.-n put t,i use i,, huilding n not her Inrirr machine. This Inttrr nrroplnnc has a span of 100 ft.; length, 44 hei-ht. .'. ft ; estimated speed. 130-130 m.p.h.; estimated useful load. 6400 Ib*. in additinn to erew and fuel necessary for i .VHP inHe flight. \l BURGESS TWIN - MOTORED SEAPLANE SCALL of FEtT McUughlin 58 Mri/n-MOTOKKI) AKHOIM.ANKS Burgess Twin-Motored Hydroaeroplane Tliis machine, besides being equipped with tin- usual complement of instruments, has the Sperrv gvroscopic stabilizer anil other impro\cd installations. General Dimensions Span, upper plain- 7 .' f t. in. Span, lower plane 51 ft. !l in. Chord, Ixith planes 7 ft. 7 in. Cap iM-tween planes 6 ft. 11 in. Ix-nplli over all :<-' ft. 5 in. II, ..-hi over all IS ft. * in. Cross writ-lit 5,380 II. s. Motors (.') Sturdevant 5A, rnch 140 h.p. ( Hiding anple 8 1 /, to 1 Climl> in in minutes 3^00 feet Spenl Miiirc, loaded 78-45 m.p.h. Planes I'pper pl.-ine is in .', sections the flat center section 12 ft. (i in. wide; the outer sections each Hi ft. 8 in. wide; and the overhanging sections 1 1 ft. -I- in. wide. The ends of the ailerons project beyond the wing tips at either side for a distance of 1 ft. 6 in. Ailerons on the upper plane arc 12 ft. 10 in. in length, minimum with 2 ft. 1 in., maximum width 3 ft. 5 in. A small balancing portion beyond the wiring tips extends forward of the rear main wing beam. Control arms are located 7 ft. in. from the inner end of aileron. With the exception of the center sections, the planes are swept back at an angle of 3 degrees. On the lower plane, this angle corresponds to a distance of 10% in. that the straight portion of the leading edge recedes from a straight line at right angles to the fuselage center. Dihedral angle, center section, upper plane, 180 degrees. Dihedral angle of other wing sections 178 degrees. I'pper and lower planes are set at a 3-degree incidence angle, equal to rise in the leading edges of 4 13/16 in. The transverse and lateral center of gravity is located 2 ft. 11 in. from the leading edge, at which point a hoist- ing eye is located. Centers of wing beams are located as follows: Front beam i' 1 ( in. from leading edge; beams 4 ft. 6 in. apart; trailing edge 2 ft. .S" s in. from center of rear beam. Wing chord, 7 ft. 7% in. Fuselage The fuselage is 27 ft. 6\'-> in. long; maximum width, 2 ft. I- in. Maximum depth between longerons, 2 ft. 11 in. The nose extends 6 ft. 11 in. forward of the main planes. The observer's cockpit is located at the nose, and the pilot is located immediately below the trailing edge of the up|>cr plane. Location of vertical fuselage members are indicated by dotted lines on the drawing. The fuselage termination is IK in. high, formed by a strut which carries the central rudder and also supports the tail float Tail Group llori/.ontal stabilizer, 16 ft. in. across at the trailing edge. Width. I ft. " ._. in. The leading edge is Straight for a distance of 13 ft. I in., then curved in a 9 in. radius to a raked angle. It is non-lifting. Klcvators are 16 ft. 8% in. from tip to tip. Maximum width, 3 ft. 8 in. Control posts located 6 ft. in. apart, one on each flap. The vertical fin is 3 ft. 2 in. high, and to it the central unbalanced rudder is hinged. The central rudder is 2 ft. 3 in. wide. In addition to the central rudder, there are a pair of balanced rudders located 6 ft. in. to either side of the rin. These rudders have a maximum height of 3 ft. 2 in. and a width of 2 ft. 2 in. Float* Floats are arranged catamaran style, with centers 10 ft. in. apart. Each float 3 ft. in. wide, 19 ft. 1 Vj in. long and 2 ft. in. in overall depth. A step 3% in. deep is located 11 ft. lO'/.. in. from the front end. Struts to the fuselage are located at the following distances from the nose: 4 ft. S in.; 4 ft. 9 in.; 5 ft. in. The dotted and dashed line indicates the water line with the machine fully loaded with a weight of 5380 Ibs. The tail float is 19 in. wide, 4 ft 8 in. long and 11% in. deep. Motor Group Motor carrying struts are located 1 1 ft. 7% in. apart. The drawing shows the motors covered in with metal cowling. Propellers are 8 ft. 10 in. in diameter, rotating in opposite directions. The motors are Sturtevant model 5 A, rated at 150 h.p. These motors are 8-cylinder, 4-stroke cycle, water cooled, with a 4-inch bore and .">'. inch stroke. The normal operating speed of the crankshaft is 2000 r.p.m., and the propeller shaft is driven through reducing gears. The weight per h.p. of the motor is 3.4 Ibs. Fuel is consumed at the rate of 26 gallons per hour, and tanks have a capacity sufficient for an eight-hour flight ^^H The Vickers "Vimv-1! type, biplane, equipped with two Holls-Hoycc 303 h.p. motors The Transatlantic Type Vickers " Vimy " This type of plane was made famous by the historic flight of Captain Alcock and Lieut. Bronton The wing span of the Vickers- Vimy Biplane is 67' 2" ' and the chord 10'-6", both wings, upper and lower, being identical in dimensions. The area of the upper wing is 686 square feet, that of the lower 614, giving a total wing surface of 1330 square feet. The angle of incidence of both upper and lower wing is S^b", whereas the dihedral is 3. The surface of the ailerons is 2-1 '2 square feet. The areas in square feet of the control surfaces are as follows: tail plane, 11-1.5; elevators, 63; fins, 17; rudder, 21.5. The Vickers-Vimy is powered either by two 350 horse- power Rolls-Royce Eagle engines or 2 Salmon engines. It was one of the former type which made the successful trans-Atlantic flight. With the Rolls-Royce its weight empty, is 6,700 pounds; loaded, 12,500 pounds, witli a fuel capacity sufficient for 8.5 hours, or a distance of 835 miles. The speed is 98 miles an hour, and an altitude of 5,000 feet is gained in 15 minutes. The ceiling is 10,500 feet, with a military load of 2.870 pounds. The weight per square foot is 9.4 pounds, and weight per horsepower 17.9 pounds. The transatlantic type Vickers " Viniy-Rolls " biplane CO Mil /ri -M( )T( )1{ Kl ) A KK< >1M . A N KS Til.- l.ouplii-.-til liiphmr, i-.|iii|.|ii-il with two Hnll-S-ott A-...I motor*. h'ronl virw of Louche nl twiii-niotorril tlyinjr hunt with two Ilnll-Siotl A -.'HI motor*. Tl 1. ral.am. \\hite "Bantam," with its span of JO feet, nrxt to a 20 pnswngrr Grahamc- White twin-motored l.iplnnr havinjr span of H9 fcrt. 62 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A group of twin-motored A. V. Roe bombing planes. The machine on the extreme left is equipped with two Sunbeam aero en- gines, in the centre two Green engines, and on the right two Rolls-Royce engines. The Avro Twin Engined Bomber Fitted with the 230 h.p. Galloway B.H.P. Motors, this machine has the following performance when fully loaded with bombs, etc. Ileic/Jit 'o 5,000 10,000 15,000 17,000 Climbing Trial. Time min. 19 \ il steel tubing, securely fasti-neil to tin- ril s. Tin- bracing plate and strut attaelmient on tin- wings are extremely lie it and simple. Tile eml of tin- struts are lilted with a snitalile hemispherical enil which tits into a specially de- signed cup headed dolt, the bolt also forming the attach ment for the bracing plate. This method of construction is patented. Engine Units Tin- power is supplied by two _':>(> h.p. Galloway B.ll.l'. Motors, driving din-et two airscrews 9 ft. 6 in. in diam i ter. The engines are mounted on special M-plv and spruce engine mountings which are l>uilt into the renter sections of the liottom wind's, forming an extremity lif(lit and rigid lias,-. The main petrol tank is mounted inimi- iliatelv l>< hind tin engine, anil behind the petrol tank is the oil tank. The radiator is mounted in front of the engine, and the whole unit is carefully faired off to reduce head resistance. A small auxiliary petrol tank is mount* d on the top plane just ai;ove the power units and is used for running the engine when on the ground and netting off. Tin petrol is fed from the main tank to the auxiliarv petrol tank, or direct to the carlmrctors of the- engine by means of a positive pump driven by a small windmill. The main tanks are provided with dial petrol level indicators, which ;l\ r. id from tin- pilot's seat. It may be as well to point out here, that practically am existing type of engine can lie easily accommodated in this machine. Any engine from .'()() h.p. to .inn h.p. being suitable, machines of this type have been fitted with Rolls- Koyce. Sunbeam and dreen Motors, with very satisfactory results. Tin- engine controls are conveniently placed at eaeh side of the pilot, the two dependent throttle controls being on the pilot's right hand side, and the magneto controls on the left hand sidi The engine controls can IK- moved together or inde- pendently, as. for example, when a sharp turn is required, one throttle ean be left open and the other closed, so that the engine thrust helps the turn. I.cvers are also pro- vided for adjusting the carburetors for altitude. Body The body of the machine is of the usual box girder con strurtion. with spruce rails and struts and swaged steel rod.s for bracing. The body rails are stiffened by IIH .-HIS Ii wood formers in the Standard Airo in inner. This construction makes the rails extremely strong and obiiates the tendency ot the rails to warp. The body is of a good streamline lorm and proinlcs ample accommo- dation for (In- enw and the bombs. The nose of the fuselage is eon red with :: ply wood and the decks and iNimh compartment are lornnd ot the same material. Un- rest ot the body being eoiered with doped fabric carried OUT stringirs to preserie the shape. To permit the rear gunner to tire underneath the tail, a sp, ,-ial ^ at i, m.idi in the floor through the rear coekpit, and a long hole is ar ranged in tin floor through which a good view downward and backwards is obtained. When it is not rei|iiin d to use this opening, it is covered hi means of a sliding dooT. Steps are provided in the side of the body and a small light steel ladder, hung from the side of the machine, enables the crew to climb easily into their pl.i Tail Unit This consists of an adjustable tail plane, the angle of in. -nli nee of which ean be varied by the pilot whilst in flight, by means of the patent Avro tail adjusting gear. The elevators are hinged to the trailing edge of the tail in the usual manner. The fixed fin is fitted on top of tin- body . and hinged to the stern post is a large bal rudder. All the empennage members are built up of spruce and steel tubing and covered with doped fabric. The tail is braced by streamline steel wire*. Controls The elevator and aileron control is of the wheel and column type. The large hand-wheel being mounted ver- tically in front of the pilot on the top of the rocking col- umn. The rudder in operated by means of foot bar in the usual manner. All control surfaces are actuated by means of flexible steel cable passing over ball bearing pulleys. Landing Gear The landing gear in of uni<|u< design, weight and head resistance having lx-en cut down to the absolute minimum without sacrificing strength. The landing gear consists of two wheels mounted on tubular steel axles, which are at- tached by means of ball joints to the body. The landing shock in taken through a special shock absorbing strut as usually employed on Avro machines, and there is a diag- onal behind this, taking the backward loads imposed when landing and tax y ing on the ground. Hear view of the Avro twin-motored Itumliiiifr Hiplanr. K F 5 o LAW50N TYPE'Cl TWIN LIBEBTY MOTOI2CD AEQAL TPAN5POCT Sca.le of l^eet s a 10 i? 14 1 Mclaughlin 64 MULTI-MOTORED AKKui'l. .\.\K> Lawson Aerial Transport The giant I .aw son ' ( I " biplane was designed from i front and rear of the cabin. On the left su|. of the cabin strictly commercial point of v i, w forward of the wings an entrance door is provided. Tins The fuselage is built to accommodate :il pass, Hi;, rs and door is of such proportions that the usual method of all the details of its construction and performance char climbing or crawling into the machine is done awav with acteristics take into consideration the s ,|,l\ and comfort P . , of the pass, liters. . . Dual controls arc provided at tli< lorward , nd of the I he seats an naililv detachable and sleeping quarters: .. cabin. < out ml wheels are is in diameter ind ar, installed for a fewer number ol passengers when cruising mounted on a tube e\li nding from one side of the bod) for considerable disl.-im , s ..... '" "'c other. 1 he wheels control the ailerons and ele- I he ten, ral specifications of the I. aw son Air transport . . vators, and the usual f, M it bar is BMO for the ruddi rs I -I arc as Follow s : , .. All control surfaces are interconnected and cables doubled General Dimensions | M t | 1( . n j| ( .,ons wood is used in the construction. l-'or Span, both pl.mes . . . .M ft. In. ,|,,. st .-dili/.ers and el, -valors both wood and steel an p Chord, both planes 9 ft. (i in. .... . . . .. . .. . . a . . . | (i ft 3 in rudders are nearly all steel. ror night Hying. CMC I.ciurtli ovtr.ill it. 7 in. lr ' I'glds arc supplied for the instrument hoard, interior ll.i.'lit overall U ft. in. ' of the cabin, and the wind's Areas Tail Group X,/. fV. The fuselage terminates in a steel tube stern post to Main planes, including ailerons . .I.TINI which is attached a rcar spar of the lower tail plane and Aill ' r "" s (l) also tail skid. The tail, of the biplane tvpe. is adjustable Stal.ili7.ers ( .') 17iJ i)iiri< . ,, 5 -$ to counteract any ofVCmMM in balancing which may in Kndilers (:l) 45 s1 "'- "'"' '" the large si/c of the machine, passengers A n ~j eg ln;l . v move freely alxuit the fuselage without any dis- Incidence of main planes 3 turbance to plane. Uuddcrs and elevators are of the bal- Did.-dral 1 anccd ty|>e. i.haek 6 e Landing Gear S ,i,ili/er settiii).' to \\\na chord 0" Ti I r j r 4 t aa" u I he landing gear is composed of two pairs of 36 by We 'ihts 8" wheels carried on large streamlined steel tube struts. M icliinc fully loaded .. 1^,000 Ibs. T | 1( . v ;lrt . attached under each engine in such a way as Performances to evenly take up the landing shocks with a minimum of ('limit iii 10 minutes with full loud 4,000 ft. strain to the wings and fuselage. luijr 14,000 ft. ( lliilinjr alible 1 to 8 Engines In, I duration 4 hours Two Ig-rylinder I.ilx-rty engines are used. They arc completely enclosed in nacelles at either side of the' fuse Main Planes loge. I S. A. ."> winu' section is used. Main planes are in Engines are placed in pusher position with profilers n sections The outer center section extends between M)' in diameter revolving in opposite directions. They the outer struts of either engine nacelle. The two lower rest on large ash beds internally braced by steel tubes. center sections run from the fuselage to outer engine Gas tanks are located in the nacelles. Kngines are ! struts. equipped with separate controls to the pilot's cotnpart- Fuselage ment, where they may IK- operated separately or together. - its arc placed at windows at each side of the body, Effective milliters are provided which add greatly to the and an aisl, Itctwcen the seats allows passage from the comfort of the passengers. / ' IIIUII THE FRENCH CAUDRON TWIN-MOTORED BOMBING BIPLANE A front view of a Caudron R 11 French Bombing Biplane. This machine is a three (3) seater and is driven by two Hispano- Suiza motors. French Caudron Biplane equipped with two Hispano-Suiza motors. The Caudron R 11 type of French Bombing Biplane. Twin motored, it carried two and sometimes three men. The nacelle projects considerably in front of the plane thereby insuring a good view. 66 MULTI-MOTORED AKKOI'LAM.S 157 The Friedrichshafen Twin-Motored Biplane This machine is ;i weight carrying type and was used for bombing purposes. It iniriii.-illv carried a crew of four. The cot -kpits wire intercommunicating, so thnt the personnel could change plan s. etc. The tnt.-il weight of tin- empty machine is 5930 pounds. load -.'?'..'(> M>s. Maximum load 8616 Ibs. sq. ft. General Description The general (lesion of the machine is shown in the at- tached drawing, which gives plan and front and side ele- vations. The principal dimensions arc as follows: Spat, .......................................... 78 ft. M .ixiiiiiini ehnnl ................................ 7 ft. fl in. Gap ........................................... 7 ft Dihedral illicit- in the \.-rti.-al plain- ............. ly,' Dihedral :IML'|I- in the hnri/.iint.il pi me ........... 6* nain planes ...................... 934.4 \n-;i nf upper 111. mi planes without flap ......... 490 Area of lower niiiin planes without flap .......... 451.4 " I. o nl per si|ii:irr fm>t .......................... 9.2+ His. \Veinht per horse pimer ........................ 16.6 His. \rr i of (lap of upper wing ..................... 21-6 ! ft. llalancc area ................................... 1 .8 of ll.ip on lower v> ing ...................... 16 Ilillanee an-a ................................... 1.56 Tulal area of lived tail planes ................... 47.6 I urea of elevator-. ......................... 3i H.il.uice area of one elevator .................... 1.7 Ana of (in .................................... iO .if rudder ................................ 19.3 II. il am i area of rudder ......................... 3 Maximum cross section 01 body ................. 19.2 Horizontal area of body ............. .......... 133 Vertical area of liody .......................... 131.9 over all ............................. . .. 4? ft The machine is built up upon a central section, to which attached the forward and rearward portions of the fuselage and the main planes. This central section com- prises the main cell :r caliin of the body, containing the tanks, bomlis. etc. It also embraces the engines and the tral portion of the upper and lower planes. The latter, together with the engine struts, are largely built up of still tube, as is also the landing gear. Tin central portion of the body, which measures 4 ft. across by I ft. S in. in height, consists of a box formation made of plywood, strengthened by longerons and diag- onals, anil transversely stiffened by ply-wood bulkheads. The bulkhead farthest forward acts as an instrument board, behind which are side by side the seats of the pilot and bis assistant. The former has a fixed upholstered si at. whilst that of the latter is folding, consisting of a light steel tubular framework with a webbing backrest. I nderneath these two seats is the lower main petrol tank. Behind this cockpit the body is roofed in with ply wood, the rear part of which roofing is detachable so as to give access to the second main petrol tank, which is at the rear end of the main body section. By this means a small caliin or covered passageway is provided, at each side of which are the racks for the smaller bombs. Central Portion of Wings The central and non-detachable portion of the upper plane has a span of 19 ft. 5 in., whilst at each side of the nacelle the lower plane fixed portion measures 7 ft. 8 in. The main wing spars in this central portion arc of steel tube, roughly 2 in. in diameter, with a wall thickness of 1/16 in. These spars are braced by steel tubes arranged in the form of an X, the manner in which the bracing tubes arc attached to the main spars being shown in the sketch Fig. 1. The lugs are built up by welding, and are pinned and riveted in position, the joint being of the plain knuckle type. The upper surface of the lower plane is, so far as the central section is concerned, covered in with three-ply wood. In this portion the main ribs are of three-ply, with spruce flanges. Between each main rib is a cut-away rib, the design of which is shown in the sketch Fig. 2. This, unlike the main ribs, is one piece of wood, and not built up. For the greater part of its length it applies to the top surface only, being cut away to pass clear of the cross bracing tubes. The plane is further stiffened with transverse members consisting of three-ply panels between each rib strength- ened by grooved pieces top and bottom. The latter are attached as shown in the sketch Fig. .S, and the attachment of the flanges of the main ribs is shown in Fig. 4. The central section of the up|>er main plane is in one piece and is covered top and bottom with fabric. In order to facilitate the reinovnl of the engines, detachable panels measuring 1 ft. 1 1 \' in. long by 1 ft. 8 in. deep are let into the trailing edge immediately over the engine bearers. These panels are socketed in front, and at the rear are Line drawings of the Twin-motored Friedrichshafen Bombing Biplane. Sketches showing details of construction of the Friedrichshafen Bomber. 68 .MlI.Tl-MOTOKI.l) AKKOl'I.ANKS B8 juiliril up at tin- trailing edge with I section sheet steel clips anil l.olts. The struts which connect the top of tin- nacelle to the uppi-r plain- art tiilinl.-ir and of streamline section, as are also tin- engine bearer strut-.. A section of on. of tin- latter is ^ivi n in I I IT- -"'- 'I'll' 1 tliit-knc.ss of the wall is mi. sixteenth of an inch. The method of attaching the lower i-nil of tin- engine struts to the tuhular steel spars is shown in the sketch Fig. <;. from whi.-h it will be seen that a weldc-d Y socket it us< d and secured hv a pin joint, the ends of the pin acting as -meliorates | c ir the attaehinent of tin- bracing wires. 'I'his sketeli also shows the lugs which respectively sup- port the detachable portion of the main planes an. I tin- vertical strut of the landing chassis. The engine hearer struts are pushed into the i socket and pinned in position, the pins lieinit afterwards hra/.ed into the socket. At their upper ends the engine struts are (ixed to the top plane spars with pin joints, as shown in Figs. 7 and 8, the attach- ment differing according to the number of wire bracings that art- to he taken to each joint. Construction of Wings The detachable portions of the wings are fixed to the renter section by pin joints, one part of which is shown in Fig. t>, the male portion being represented in Fig. 9. The chord of the wing in the line of flight varies from approximately 7 ft. 8 in. to ~ ft. .'. in., and the wing sec- tion is shown shaded in I'ig. 10. In order to provide a basis of comparison the l( A.I . \^ wing section is super- imposed and drawn to the same scale. The main spars are placed one meter apart, the front spar being -J7'-' iiims. in the rear of the leading edge. Both spars are of the built up ln>x type, as shown in Figs. 11 and I -'. Tin- former is the leading spar and the latter the rear spar. These spars arc of spruce, and each half is furnished with several .splices, so that the greatest single 1'iigth of timber in them is not more than 11 ft. The splices, which occur in each half alternately, are of the plain bevel type about 1 .1 in. long and wrapped with fabric. A t.ibric wrapping is also applied at short intervals along the spar. Internal cross bracing between the main spars is af- forded by steel tube cross memlxT.s and cables attached us shown in the sketch Fig. 9. Tin- main spar joint consists of a steel plate 1!) mms. thick embedded in the spar end and held in position by ~> bolts, which pass through a strapping plate surrounding ,| of the spar. This plate also carries the attach- ment for the bracing cable and is furnished with a spigot which locates the bracing tub*-. It will be seen that at this point the spar is provided with ta|M-rcd pat-king pii hard wood glued and held in position by fabric wrapping. The main ribs are placed :i(i() mms. apart. Between them are auxiliary formers, consisting of strips of wood .'i> mms. x in mms. thick, which run from the leading to the rear spar. The main ribs consist of ply wood -ockcttcd into grooxed spruce llangcs. which are tapered off as shown in Fig. k except where they are met by a longitudinal stringer. The leading edge is solid wood moulded to a semi-circular section of approximately OS . d : ameter. Where the rib web abuts against it, pack- ing pieei s are glued i ach side. Hetwieii the main spars the web of the rib Is dn id< d In thr .1 strips into lour panels and in each of tlnse it is perforated, hiving an edge til round about 7- mms. wide. As shown in 1 -'ig. !>. the upper flange of the main ribs is carried char of the hading spar by means of packing pieces. In the case of the rear spar, packing pieces arc also used under the rib flange ns shown in Fig. 12. The lower main planes for a width of about 2 ft. 3 in. at their inner end an- covered as to their top surfaces with three ply wood. The interplnne struts arc attached to the main spars by joints of the type shown in Fig. I k. This, it will be seen. follows the typical (uriiian practice of partially universal jointed mountings for the cable attachments. At the points of attachment of these strut joints, suitably tapered packing pieces of hard wood surround the spars, which at these points arc also wrapped with fabric. Struts Outside of the center section the interplane struts are of wood built up, ns show n in the section Fig. 1.1, of five sepa- rate pieces. The curved portions arc of timber which has not yet been identified, but is apparently of poor quality. The cross web is of ash. The strut is wrapped at fre- quent intervals with strips of fabric and is fitted with a socket joint of the type shown in Fig. 16. The outer pair of struts are of smaller section than the main struts, but are built up in a similar manner. Their section is 125 mms. x 10 mms Ailerons The framework is principally of welded steel tube wrapped with fabric. A notable point is the thick section of the leading edge of the balanced |x>rtion, us shown in Fig. 17. Fin and Fixed Tail-Planes The framework of these is steel tube and in the case of the tail-planes wooden stringers running fore and aft are arranged at intervals. The tail-planes are supported by diagonal steel tubes of streamline section, on the under side of which sharp steel points are welded to prevent these stays being used for lifting purpose*. Elevators and Rudders Tin- framework in each ease is of steel tube, the main tube being 35 mms. in diameter and the remainder 15 mms. Bracing Throughout the wings, both internally and externally, the bracing is by means of malt is) rand steel cable. Fuselage (Rear Portion) At the after-gunner's cockpit the section of the fuselage has a rounded top. which is gradually smoothed down into flat. The section, for the greater part of the length, U rectangular, and the frame is built up in the usual man- ner with s<|iiare section longerons and \crticals. the joints being arranged as shown in Fig. 18. The cross bracing wires along the sides, top, bottom, and diagonal are of steel piano wire and are covered with strips of fabri. The inside of the front cockpit. View looking down the inside of the fuselage, showing trap door and after- gunner's folding seat. Flo. 19. Flo. It. FIG. 12. Details of construction of Friedrichshafen Bomber. 70 Fie. 23. Mn.TI-MOTOKKI) A KK< HM.ANKS 71 shown in this sketch, where they In adj ic.-nt to tlir fabric fuselage covering. Tin- vertical and liori/.ontal compression members are located by spigots. Tin- joint consists of plate which completely Mil-rounds the longerons, its two mil-. being rhcted together to torin a diagonal bracing strip. 1 or tin- last few liit ;it tin- tail the fuselage is covered with thin three-ply. Tin- fuselage is coMTcd with f.-ilirii-, wliicli is held in position l>\ i 1. icing iindrrni-atli and is consri|iiciitly hodilv n movable. '1'ln- lliKir of tin- after gunner's cockpit is elevated above the hottoin of the fiis' l.i^i I iniiiediatel V underneath this cockpit is a large trap door, shown liy dotted lines in the plnn view of the aeroplane. This is hinged at its rear- ward end and furnished with two large celluloid windows. It is held in its " up " position by a long spring and a snap clip. No me ins could he found bv which it could he ii\. ,1 in its dosed position. As footsteps are provided for all the cockpits, this trap door is evnlentlv not intended for ingr. *s ,i l( | e^n-ss. It rould he employed in connection with a machine pin tiring backwards, as in the (iotha. but no iiiachini gun mounting was fixed in this machine for this pur). Tin- rear portion of the fuselage is attached to the cen- ter section of the body liy a clip at each corner. This is shown in 1 ig. 1!'. The rear portion carries a male lug, which engage s with the two eyes, and is held in position ,fhs holt. lour other l>olts in tension pass through the sheet metal clip, as shown in the sketch. In each case the hit's arc furnished with sheet steel extensions which, as shown in the sketch Fig. 19. are sunk flush into the top mid bottom surfaces of tin- fuselage longerons and are there held with three holts. The corner joint is welded ii i-l. and there is an additional diagonal sheet steel point which serves the secondary purpose of providing an anchorage for the bracing wires. As this fuselage joint is level with the plane of rota- tion of the propellers, it is armored both on the nacelle and on the rear portion of the fuselage with a hinged covering of stout sheet steel lined with felt. A plate of armor a foot wide also extends down each side of the nacelle at this point. Forward Cockpit This is attached to the main body by four bolts with dips similar to those just described. It consists of a light ien framework, covered throughout by three-ply. The cock-pit can be divided off from the main cockpit by means of a fabric curtain. Its occupant is provided with the folding seat, and manages a gun and the bomb- dropping gear. Engine Mounting The engine bearers have the section shown in Fig. 20, and arc each built up of two pieces of pine united by s. On their top surface they are faced with ply- wood, and at the bottom with ash. A strip of ash applied to the upper outer corner of the bearer gives it an " L" section, and has screwed into it the threaded sockets for tb set screws of the lower part of the engine fairing. The engine bearers taper sharply at each end. They are mounted on the " V " struts by means of acctvh in wehhd brackets, constructed as shown in sketch. Fig. J 1 . These. it will IK- seen, are of box form, and form a liner round tin streamline tube. The engine cow linn is a particularly fine piece of work, and two views are given in sketches 22 and 23. Tin- lower portion is attached to the i ngine hearer* by set screws, but the up|M-r part is readily d tachable, being furnished with turn buttons. Tins cowling allows the cylinders of the engine to be exposed to the air. A large scoop is placed in front, so as to permit a free flow of air OUT the bottom and sides of the craiikchamucr, whilst at the rear three Inrgc trumpet shaped cowls arc provided so that a draught of air is forced against the craiikca.s<- in the neighborhood of the carburetor air intake. In the rear the fairing abuts against the propeller nave, whilst in front it is attached to the radiator. It will IK- noticed that at each side of the radiator are narrow air scoops, the object of which is to promote a draught past the oil tank and front cylinder heads. Engines Theraiotors are the standard 260-h.p. Mercedes with six cylinders in line. Full details of this engine have been published, and it is only, therefore, necessary to notice one or two points in connection with the installation. A new departure is the interconnection of the throttle and ignition advance controls. This is carried out in tin- manner illustrated diagrammatical ly in Fig. 24. It will be seen that a considerable movement of the throttle can be made independently of the ignition advance. In the Mercedes carburetor the throttle is so arranged that it cannot be fully opened near the ground without providing too weak a mixture, and it is thought possible that the full ignition advance is not obtained until this critical opening is reached. On several German bombing aeroplanes grease pumps for lubricating the water spindle have been found. Fig. 25 shows the design as fitted to the Friedrichshafen. It consists of a ratchet and pawl operated grease pump, se- cured by a bracket to one of the engine struts, and worked from the pilot's cockpit by a lever, and a stranded steel cable passing over a pulley, the pawl being returned by a long-coiled spring. The exhaust pipe is of new design, although it incor- porates the well-known expansion joints attached to the flanges. It is fitted with what amounts to a rudimentary silencer, whereas in previous machines of a similar type to the Friedrichshafen an open-ended exhaust pipe was used. Radiators Each radiator is provided with an electric thermometer fitted into the water inlet pipe, us shown in sketch. Fig. J7, these thermometers being wired up to a dial on the dashboard, which is furnished with a switch, so that the temperature of either radiator can be taken independently. The radiators consist of square tubes to the number of 4134. and measuring roughly mms. each way. The radiator block is V shaped in plan, and each is provided with a shutter which covers up a little more than Construction details of the Friedrich shafen Bomber. Kio. 32. Main landing chassis, tail skid and ma- chine gun mounting in the front of the fuselage. MILTI-MOTOKKl) AKKOl'I.ANKS a third of tin- cooling surl u i . This shutter is fitted with ;i stop, so Unit when fully n|)i-iifd it lirs ill tilt- line ot flight of tin- :ii-ro|)laiir. It is o|n-in-d or clos. ,1 :u , -onling In ciri iimstances liy tin year, show M in tin sketch. I || of Inch the h indie is iniiunted on the roof of the nacelle, iniinriliatelv behind the pilot's seat. Three positions ar< provided for the handle, which operates tin two shutters simultaneously Iv means ot return eahles. Iminediati 1\ .ilio\e the main radiator, in. I let into tin- upper main plain- between the front spar ami the I. idiii:: i .In. . is a small auxiliary tank, illustrated 11 This is furnished with a trumpet shaped \ent in the direc- tion of the line of flight, and is furnisln d with two oiith Is, one to the Inad of the main radiator, ami the other to the water pump. The function of this tank is evidently to it the pump from priming. Oil Pump Tin main supply of oil is carried in sumps forming part of the hase chamber. A secondary supply of oil. from which a small fresh cliarije is drawn at every stroke of tin- oil pump, is contained in a cylindrical tank supported 1>\ brackets from the engine struts, and placed immediately In-hind the radiator. This tank has a capacity of 25 liters ;, i _. gallons. Kach tank is furnished with a glass level. w Inch is \ isihle from the pilot's seat . Petrol Tanks The two main tanks which are placed, one under tin- pilot's seat and the other at tin- top rear end of the nacelle, contain J7 11 liters ."i!i.. gallons each, and arc made of hri". I ich is provided with a Maximal! level indicator, which employs the principle of n Hoat operating n dial by means of a cable enclosed in a system of pipes. A hand pump is fitted conveniently to the pilot, and pressure is normally provided by the pumps installed in each engine. An auxiliary tank, holding approximately l:i gallons, is concealed iii the upper main plane, not imme- diately over the nacelle but a little to the left side. This auxiliary tank is fitted with n level, as shown in Fig. 29, which is visible from the cockpit. The auxiliary tank nppiars to be used only for starting purposes. It is cov- ered with a sheet of fabric held in position by "patent .' Ts." Engine Controls Kiinning from each engine to the nac-elle is a horizontal !iit. containing the various engine controls. ion showing the arrangement of these inside the fair- ina is itiv.n in the sketch. Fig. 30. The leading edge of the streamline easing consists of a steel tube, to which are weld-d narrow steel strip brackets, to the rear end of which are bolted thinner strips which are hinged in front to the tuln-. The whole is then enclosed in a sheet alumi- num fairing. Through the leading tube passes the throttle control rod h engine, the two throttles being worked either to- gether or independently by the ratchet levers, shown in I. Tlnse are mounted on a shelf convenient to tin- pilot s left hand. This control requires a considerable number of bell cranks and countershafts, but was notice- ably trie t re. in backlash. The throttle is opened by tin- pilot pulling the levers towards him. On tin dashho-ird an !.. r. volution counters and two air pressure indicators. Tin metal parts ol tins, dials are p-iinti d n il lor tin li It i nuiin am! i;n . n for tin right, and tin same coloring applies to the magneto switches, one of which contains a master switch which applies to both in mm tos on both i urines. Piping The various sv stems of piping are distinguished by 1 ii.g painted dilnr. nt color., thus the petrol pi|M-s are * lute, arrows licing also painti d on (him to show the direction of How; air pressure pipes arc blue, ami | i for cable controls gray. Propeller The prop Hers are each 8.08 meters in diameter and are made of nine laminations, which are alternately wal- nut and ash, except one which appears to be of maple. The propeller has the last 20 ins. of its blade edged with brass. The pitch is approximately 1.8 nieti rs nnd the maximum width of the blade '-'-JO millimeters. Controls Only one set of control gears is fitted, but as pointed out, tin- seating accommodation is so arranged that any of the crew can take charge if, and when, necessary. The elevator and aileron control is shown in sketch Fig. 32. It consists of a tubular steel pillar mounted on a cranked cross bar at its foot. The ailerons are worked by cables passing over a drum on the wheel, whence they descend through fiber (juidcs on the cross bar to another wheel mounted on a countershaft below, from which they are taken along inside the leading edge of the lower wing and finally over pulleys up to the aileron levers on the top plane. The latter are partially concealed in slots let into the trailing edge of the wing. The upper and lower ailerons arc connected by means of pin jointed tubular steel struts of streamline section. It will l-.e observed from Fig. 82 that a locking device whereby the elevator control enn l>c fixed in any desired position is tilted, and consists of a slotted link which can be clamped by a butterfly nut to the control lever. This link is hinged to a small bracket attached to the panel below the pilot's seat. Fig. M shows the rudder control, from which cables are taken over pulleys and through housings in the nacelle and finally to the end of the fuselage. The cranked rud- der bar is of light steel tube and is arranged to be placed in the pivot box in either of two positions. It is furnished with light steel tubular hoops which act as heel rests nnd are adjustable. A locking clip is fitted on the floor of the cockpit so that the rudder can be fixed in its neutral position. A novel type of trimming gear is an interesting item of the control. Movement of cln elevator control from the normal upright |x>sition of the stick is made against the tension of one of two springs which can be alternately extended and relaxed by means of a winch connected to them, as shown in the diagram. Fig. 81. Normally these TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING springs tend to bring the control stick back to a central position, in which the elevator lies flat, but if one of the springs is tensioned by winding up the winch in clock- wise direction, the position to which the stick will tend to come when released will be such as to set the elevator at a positive angle. This winch gear, which is illustrated in Fig. 3:5, is mounted on the right-hand side of the nacelle, and is therefore under the command of the pilot's com- panion. The crank is furnished with a locking pawl, which engages with a ring of small holes bored in the plate of the winch. The steel springs used in conjunction with this apparatus are some 3 ft. long and about % in. in diam- eter. The inscription behind the winch read : Nose heavy Right wind. Tail heavy Left wind. Landing Gear As might be expected, the landing gear on this machine is of massive proportions. Two vertical streamline sec- tion wood-filled tubes descend from the center section wing spars, immediately under the engine, to a bridge piece or hollow girder made of welded steel. Through an oval hole in this girder a short axle carries two 965 mms. x 150 mms. wheels (38 in. x 6 in.). These work up and down against the tension of a bundle of steel springs about 1/2 in. ' n diameter and made of wire approximately 1-16 in. thick. The steel girder is extensively pierced for lightness, and the edges of the holes are swaged inwards. The axle is prevented from moving sideways by plates, and is pro- vided with short steel cables which act as radius rods and connect it to the front of the girder. The whole of the box girder is covered in with a detachable bag of fabric, which extends up to the small cross bar mounted imme- diately above the girder. Mudguards are provided behind each landing wheel for the purpose of preventing any mud or stones dislodged by the wheels from coming in contact with the propellers. From the front and rear of the box girder streamline tubes are taken to the ends of the main wing spars, where they abut against the nacelle, and these diagonals are further braced with streamline steel tubes. Both the vertical and diagonal tubes are held in split sockets so as to be easily replaceable if damaged. In addition to the four main landing wheels, a fifth is mounted under the nose of the fuselage. This wheel is 760 mms. x 100 mms. (30 in. x -1 in.). It is mounted on a short axle, which is capable of sliding up and down slots in its forks against a strong coil spring, and it is also capable of a certain amount of lateral movement along its axle, also against the action of two small coil springs. The tail portion of the fuselage is protected by a fixed skid made of wood but shod with a steel sole. This is fitted with a small coil spring contained inside the fuse- lage. Wiring The whole of the wiring system on the machine is very neatly carried out. There are three main systems ; firstly, the ignition wiring, which is contained for the most part in tubes of glazed and woven fabric ; secondly, the heating system, for which the wires are carried in flexible metal conduits ; and, thirdly, the lighting system, in which a thin celluloid protective tubing is used. Wires are run from the nacelle along the leading edge of the upper planes to points level with the outermost strut. Here they termi- nate in a plug fitting placed behind a hinged panel. Ap- parently lamps are intended to be served by the circuit. Immediately in front of the pilot's seat a universally jointed lamp bracket is mounted on the outside of the nacelle. The exact purpose of this lamp is not known, as it could not illuminate any instruments. Armament Both the forward and rear cockpits are furnished with swivel gun mounts carrying Parabellum machine guns. These mounts consist of built-up laminated wood turn- tables working on small rollers, and carry a U-shaped tubular arm for elevation. This arm is hinged to a plunger rod working through a cross head, and arranged so that the arm is normally pulled down flat on the turn- table by a coil spring. The plunger can be locked in any of a series of positions by means of a bolt operated by a hand-lever through a Bowden wire. A second lever allows the turntable to be locked at any desired point. A perforated sheet-metal shield protects the cross head and spring. Small shoulder pads are fixed on the turntables, of which that in the forward cockpit has a diameter of 2 ft. 1Q1/2 in., whilst in the rear the diameter is 3 ft. y 2 in. The after-gunner is prevented from damaging the pro- pellers by two wire netting screens, supported by tubular steel brackets, placed on either side of his cockpit. These are sketched in Fig. 36. In addition to these two guns, provision is made for mounting a third in front of, and to the right of, the pilot's cockpit, where it could be managed by his com- panion. For this purpose a clip is provided immediately under the coaming of the nacelle, and the handle of this protrudes through a slot in the dashboard. The clip works on the eccentric principle, and appears to be self- locking. Its construction is shown in detail in Fig. 37. A rack for Very lights is mounted on the outside of the nacelle convenient to the pilot's companion. INSTRUMENTS Airspeed Indicator Considerable interest attaches to the fact that this Friedrichshafen Bomber is the first enemy machine brought down which has been found provided with an airspeed indicator. This is of the static type, embody- ing a Pitot head of the usual type. The indicator has a dial of large size, and is altogether a much more bulky instrument than any for a similar purpose used in British machines. An investigation of its mechanism is being made. Altimeter This is of the usual type, reading to 8 kilometers. Level Indicator This is a somewhat crudely made device, employing two liquid levels, as indicated in the diagrammatic sketch MULTI-MOTORED . \KHoiM.. \M-.S 75 Fig. 38. It will be seen th.it tin- reading uixcs tin- pilot an exaggerate i! idea of tin- angle nf mil. Tin glass tiiln-s art- sealed u]>, and contain n d irk blur liquid. Revolution Counters Tin- dials i;i\c readings from ;(IKI to HIiici r.p.ni. The sector In tw.eii l.;ou and l.'.oii i, painted Mark, and these figures an marked with luminous compound, as also is tin indicating hand. Air Pressure Gauges Tlu-M- r.-ad from u to o.~. kilogrammes per square ccnti- meter. Thin is a r. d mark ajr-iinst tin figure 0.25 kg. Electric Thermometer Dial This dashboard instrument consists of a box-type me- ter, the dial reading from II to loo ,|, - ( The figures and ': are accentuated liy red marks. A switch at tin side of the l>o\, having positions marked 1 and "2, allows the temperature of either radiator to be read. Petrol Level Indicators These art ,.l the \Ia\iinall type, and employs a float immersed in a tubular guide in the tank. This float com- municates iu motion to a tinker working over a circular dial, by means of i thin cord passing over pulleys. These are incasid in pipes, which are under the same pressure as (he tank. Electric Heating Rheostat This is illustrated in Fig. 39. It is marked Aus (off), Schwach , xxiak>. Stark (strong). There arc two sep- arate resistance coils. , imMing th. rheostat also to per- form the function of a change-over switch. Wireless The machine is internally wired for wireless, and the left hand engine is provided with a pulley and clutch for drix-ing the dynamo. Reference to Fig. 22 will show that this is designed to be mounted on a bracket carried by the outside front engine bearer strut, and that the engine fairing is molded to receive it. Bombs and Bomb Gear At each side of the cox end in passage .iy in the nacelle are l.omb racks capable of holding five *3-pomid,r (12 kg. ) bombs. I nderneath the naeell. an , -irrieil two large tubular ir.m.s. lilted with cradles of steel cable, and furnished with the usual form of trip gear. These racks would, it is l.elicxcd, l>e capable of SUp- portin- a :;IMI kg. bomb apiece. The homlis carried, how- c\cr. exidently xary with the radius of action ,,,,r which the aeroplane has to operate. The Inr^e racks are not permanently attached to the nacelle, but |x he r. moved as required. Inside the front cockpit from which the release of the bombs is coiiductid. there are s, MII triers for the small bomb racks and two levers for the lar^e l>oml> trips. The cables for this gear are carried under the floor, and are painted different colors for distinction. Bomb Sight The homb sjjfht carried on tin machine presents no new features, and is of the ordinary German non-precision type. Fabric and Dope Two entirely different kinds of fabric are employed in the I'riedrichshafcn machine. The wings are covered with a low-grade linen of the class which is employed on most of the enemy machines. It is white in color. Com- pared with that of British fabrics, the tensile strength is fairly good. This fabric is covered with a cellulose acetate dope, and is camouflaged in large irregular lozenges of dull colors, including blue-black, dark green, and earth color. The other fabric, which is applied to the fuselage, tail planes, rudder, elevator fin, and landing gear, is appar- ently a cheap material, much inferior to British fabrics designed for a similar purpose. This fuselage fabric is dyed in a regular pattern of lozenges, the colors being hardly distinguishable from black. The dope is acetate of cellulose. GOTHA TWIN ENGINE BIPLANE, TYPE GO. G; TA/1KS. 76 Mil /n-.M( >T( )H KI ) A KK( )IM ,.\ X KS 77 \ Ciotha twin -iiuitured I'li-hrr Hipl.inr. The Gotha Twin Motored Biplan Type GO. G5 Tl..- ,1, tails of tliis machine do not differ to any great fiord xt.-nt from tlms,- of th<- usual German construction. Ow Thr p-nt-ral drtails of this plane are: KnKi"<- rrnt.-rs ............... II ft. , ,. Knirlncs (Mercedes) ........... 360 h.p. each .spa,, ,!,, plan,-) ,,v,-r tips of P] ft. S,-t l.m-k of plan,. ............. 4' I'roprll.-r (diainrtrr) ........... 10 ft. 2 In. Span (l,,,tt,.,n plan,-) ^^ Qf undpr ca whw|g rf f , , n Imp ........................... * II* " 2 '/ 'n. to 7 ft. 6 In. 11 fi ' f , , % rhrec virw^ nt the German Gotha twin-motored Biplane. GERMAN A.E.G TWIN ENGINED 520\? BOMBING BIPLANE MULTI-MOTORED AKKoi'I. .\M.s Two ii w. n," Hi.- (Irrinni \. I''.. (' twin -inoton (I lli|i|,iiir. The German A. E. G. Bombing Biplane Fundamentally tlie A. E. G. bomber resembles the (lot ha biplanes. In dimensions, however, the two ma- chines iliHVr considerably, the Gotha being somewhat larger. Also the A. K. (i. lias its two airscrews placed in front of the main planes, whereas in the Gotha they are " pusher " screws. As in tlir (iotlia. the wings of the A. I. (i. are swept back at a 5 angle and are also placed at a dihedral angle, which appears to be greater in the bottom than in Ihe top plane. The span, it will be seen from the scale drawings, is the same for both planes, and amounts to .1 7 ft., while the overall length is about 30 ft. in. The ailerons, which are of a peculiar shape, are fitted to the top plane only, and are operated by a crank lever working in a slot in the plane. This arrange- ment would appear to be in general favor with German designers, whereas it is rarely or never met with in Allied chines. The tail planes, which are of the monoplane type, con- sist nf fixed stabilizing planes with an area of SO sq. ft., and a vertical fin, to which are hinged the elevators and rudder respectively. Both elevators and rudder have for- ward projections in order to partly balance them, thus relieving the pilot of a certain amount of the strain of working the controls. Maximum height of rudder, 6 ft. 9 in.; area 17 sq. ft.; maximum span of elevators, 12 ft. ii in.; total area, 25 sq. ft. A tail skid is fitted under the sti-rn of the fuselage, and is sprung, not by means of rub- ber shock absorbers as is usually the case with our ma- chines, but by means of coil springs. The same is the case with the landing chassis, where coil springs arc also us< d instead of rubber. Whether this " indicates a short- age of rubber " in Germany, or whether, for machines of such large dimensions and heavy weight, it has been found mnrr suitable, it is not possible to say. As already mentioned, the material used in the construc- tion is, with very few exceptions, steel, practically the only parts made of wood being the ribs of the main planes. The main spars are in the form of steel tubes, which ii rattier surprising in view of the fact that about the worst use to put a circular or tubular section is to employ it as a beam laterally loaded, since much of the material of such a section will be situated at or near the neutral axis, where it is adding weight without contributing greatly towards the strength. Possibly the tube has been chosen, in this instance, for reasons connected with the manufac- ture rather than from considerations of structural suit- ability. The method of attaching the root of the main spar to the center section of the top plane is shown in one of the sketches. The short length joining the center section spar and root of wing appears to be turned from the solid, hollowed out at one end to receive the center section spar, and having machined on the other a forked end to receive the root of the main spar. The strut socket. which resembles those usually found on German machines, is attached to it by welding. Like the rest of the machine, the fuselage of the A. K. (i. bomber is built up of steel tubes, this material being used for longerons as well as for struts and cross members. These are connected by welding and the joints are stiff- ened and anchorage provided for the cross bracing wires by triangular pieces of sheet steel welded to longerons and struts. With regard to the accommodation for the occupants, this is divided into three divisions. In the front cockpit at the extreme nose of the body is a seat for tin- bomber, who views the ground below and obtains his sights through a circular opening in the floor. On his right the bomber has a rack holding bombs; these are presumably not of a very heavy caliber. Under the center of tin- body there is another bomb rack carrying the heavier pro- jectiles. Near the inner ends of the lower plane there are fittings for an additional supply of bombs. The ma- jority of the bombs, however, arc not, so far as it is pos- sible to ascertain, carried under the body and wings, but inside the body. 80 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Curtiss Model 18-B Biplane After the successful trials of the Curtiss Model 1 8-T tri- plane, the two-seater 18-B biplane was brought out by Curtiss Engineering Corporation. The biplane is built around the same fuselage and power plant as the triplane, but having a lesser overall height the gunner has a wider area of fire. The housing of the engine is particularly neat ; it is en- tirely encased with the exception of the exhaust stacks, which are streamlined. The removable cowling around the engine makes the power plant accessible for adjust- ments and repairs. As in the triplane, all interplane cables are of true streamline. Where cables cross, they are clamped to- gether by streamlined blocks. Another peculiarity of this machine is the employment of ailerons on the lower plane only. These ailerons are operated by steel tubes running through the lower plane and directly connected to the pilot's control stick. This principle entirely eliminates all outside control cables and rigging. Rudder and elevators are operated by levers enclosed in the fuselgae termination thereby doing away with all out- side control cables. There are no external braces for the stabilizer or fin. General Dimensions Span, upper plane 37 ft. 5% in. Span, lawer plane 37 ft. 5% in. Length overall 23 ft. 4 in. Height overall 8 ft. lOy., in. Chord, upper plane ft. 54 in. Chord, lower plane ft. 48 in. Stagger ft. 16 9/16 in. Gaps, between planes 5 ft. in. Weights Pounds Weight, fully loaded 3,001 Useful load 1,013 Performances (Altitude) Feet Service ceiling 23,000 Maximum ceiling 23,7.50 Climb in 10 minutes 12,500 Climb in 10 minutes (light flying load) 16,000 (Speed) Highspeed (m.p.h.).. lfiO.5 158.5 157.5 155 152 Altitude Sea SflOO 10,000 20,000 15,000 level feet feet feet feet Low speed (m.p.h.) . . 59 68.2 73.6 79.8 86 Kconomical Speed (m.p.h.) 80 85 92 100 118 (Climb) Kate of climl, (ft. per minute) ...2390 1690 1040 580 210 Time of climb (minutes) 2.5 6.3 12.9 27 (Endurance) Miles Hours High speed (sea level) 283 1.75 Economical speed (sea level) 536 6.7 Main Planes Planes are in flat span. There is no dihedral nor sweep-back. Main planes are in five sections. Center section over the body 30 in. wide. Outer section 17 ft. 5% in. in span. Overall span 37 ft. 5% in- Lower plane in two sections at either side of the body, each 17 ft. 5% in. span. As indicated on the accompanying line drawing, the ribs are spaced about 6 in. apart. Instead of the usual two main wing beams, the Model 18-B employs five main wing beams, the idea being to more evenly distribute the loading on them. The chord of the upper plane is 54 in. Forward main wing beam located 9 in. from leading edge. Wing beam over the rear fuselage and interplane struts 2 ft. 9 in. from leading edge. Chord of lower plane 48 in. Forward main wing beam 9 in. from leading edge. From this the other main wing beam members are spaced 75/16 in. apart. Ailerons on the lower plane have a very high aspect ratio, being 13 ft. 5 1/16 in. in length and 10% in- wide. Struts over the fuselage are spaced 30 in. apart. From these the intermediate interplane struts are centered 6 ft. ll/> in. From intermediate struts, outer struts are cen- tered 7 ft. 81/2 in. This leaves an overhang of 43% in. Fuselage The fuselage is of monocoque construction, finely stream lined. Overall length, 21 feet. Pilot's cockpit is below the trailing edge of upper plane. Aft of the pilot, the gunner's compartment is arranged so that the gunner has a wide range of fire for the two Lewis machine guns, one of which is located on a rotatable Scarff ring surrounding the cockpit, and one which fires through an opening in the under side of the fuselage. Landing Gear The track of the landing gear is 59 5 /s in. Wheels 26 in. in diameter. The axle is located 44 1 / 4 in. from the nose of the fuselage, and 491/2 in. below the center line of en- gine. With the machine in flying position, the center of gravity of machine occurs at a point 16.6 in. behind the axle of landing gear. When at rest on the ground, a straight line from the landing wheels to the tall skid makes an angle of 1 1 de- grees 15 minutes with the center line of thrust. Tail Group The triangular fin is 3 ft. in length and 3 ft. 6 in, in overall height. Rudder, 46 in. in overall height and 31 11/16 in. in width. The stabilizer is divided at either side of fuselage. Maximum deptli at the body, 2 ft. 5 in. Maximum span overall, 10 ft. 10l/ 2 in. Elevators are 18% in. in width. Engine Group The engine is a Curtiss Model K-12 engine. Two Duplex type carburetors are used. They are lo- cated between groups of cylinders. Carburetors are sup- plied with an auxiliary altitude hand-controlled air valve and also with non-back-firing screen. The propeller is 9 ft. in. in diameter. In flying posi- tion, the tips of the propeller clear the ground by 81/2 in. When the machine is at rest there is a clearance of 17 1 /.. in. between the propeller tips and the ground. Ml -LTI-MOTOKKI) AEROPLANE 81 The Curtis* " Oriole " Biplane Tlu- "Oriole" was brought out to (ill tin- need of a Main Planet ni.-ii liiin- tin- sol,- |iur|iosf of which is tin- carrying ot pas |>t for tin ccnti-r section, ninill plnnrs are made up si liters in i sit', and comfortable manner. A door is pru of sections similar in ->/< .-iiui ar..-i Main wing sections v iiled tin tin- left Mtlr of tin- hotly i indica'.i il by dashed are set at a I 1 - tli v r ' ' ililnilr.il jingle, lint- on the drawiiii: i, so the compartment is easy to get into. Portions of the ni.-nn planes jirt- flit away next to the Tin- i;i neral speeitientiiins an-: bodx anil null .- section to pt-rinit wide \ision rnngt- for General Dimensions passengers ami pilot. S '""' '"'>"" '','"" ' Fuselage and Landing Gear Snail, lower plain- ' ". III. ( 'lior.1. Loth plaii.-s 5 ft. o iii. ' llr ntOfft is v!* ft. X in. ill overall length. IU sec- L.-iiL'tli. overall .'A ft. il in. tion is oval, .S ft. ' in. liy X ft. H in. With tin iis-iin . tin H.-i-lit, OMT.-I|| ft. A in. fusel.-mr ialiis :i.'-, H>. Provision is made fur carrying two passengers seated Weights ^ ,,,), |, v ,|,1,. i,, (). forarcl nn-kpit Jinil the pilot in the r. fnlh I... -I , """ aft '' r '''^l 1 ''- C "" lr " ls l landing chassis. \\'hei-ls art- -'(! in. x M in., .spaced ft. Pd (43 *) tin. apart. Oil (I (rals) :W .,.| ()| l (jo \\ ing tips nn- provided with cnne bow skids, In low the Passt-inrrr or .itlirr |...ul 3iO outer wing struts. Speed Tail Group M.l'.ll. M.l'.ll. M.l'.ll. Stahiliascr It) ft. 1 .1 in. in span. >' ft. (i in. in mnximum '"' ft - width. The stahili/.er is tlivitletl nnd symmetrically dis- M.IMMIIIIII speed - 8S.O -" " * Mniit.i.im sp,.,.,| 475 5I.H 56.0 P os 1 *" side of the body. .niit-al spt-ftl 60.0 64.5 71.0 Klev.-itors. I ft. (5 in. wide. Climb ' '" '-' ft - <; in ' w ' 300 , bs Useful load ..................................... 700 lbs Motor, Aeromarine .......... 100 h p Speed Range ...................... ...'.'.'.'.'.' .'.'.' .'78^2 m.p.h. I limb in 10 minutes 3)500 Planes In form, the wings are designed after the R. A. F. 6 pattern. Leading edge of planes are covered with thin veneer to maintain the correct front curvature. Ribs are of lightened section, spaced about 12 inches apart. The rib webs are reinforced between lightening holes to protect against shear. Struts are hollowed to lightness as much as practical. In the internal wing bracing, separate wooden struts and not wing ribs carry the drag of the wings. Fuselage Longerons are of large section, lightened at points where the strength would not be impaired. Consideration has been given to the rough usage to which the bodies of school machines are subjected, and all wires, turnbuckles and fittings are designed accordingly. The fuselage is 22 ft. 6 in. in length, 2 ft. 6 in in its maximum width, and 3 ft. 6 in. in over all depth at the 82 pilot's cockpit. Both cockpits are arranged with a full complement of instruments. Tail Group The stabilizer is divided and mounted on either side of the body. In design it is of the double cambered type. The sections of the stabilizer are quickly detachable from the fuselage. Elevator planes are each attached to the stabilizer by four hinges. From tip to tip the elevator planes meas- ure 10 ft. 9 in. across; width, 2 ft. 5 in. The rudder is of the balanced type and of streamline section. The frame is formed of steel tubing. From the bottom of fuselage the rudder reaches a maximum height of 4 ft. in. The balanced portion extends 1 ft. 3 in. forward of the rudder post, and the main portion 2 ft. 1 1 in. to the rear of pivot. Landing Chassis Axles are li/., in. diameter. Between the wheels the tube is 134 i n . in diameter. Walls of the axle in the hubs are 8/16 in. Hubs have bronze bushings. Motor Group Provision is made for the installation of the new Aero- marine 8-cylinder 100 h.p. motor. The gear ratio is 7 to 4, turning an 8 ft. 4 in. Paragon propeller with a 6 ft. pitch at 1400 r.p.m. The motor is 4-cycle, with a bore of Sy 2 in. and a 5% in. stroke. Delco starter and ignition are provided and built in as an essential part of the motor. THE BELLANCA 35 HP ANZANI LIGHT of f.t 3 4 s e McLvMUb 83 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Bellanca Biplane, .showing the neat appearance of the warping wings and streamline Locly The Bellanca Biplane The light passenger-carrying Bellanca biplane has been designed to answer the requisites of quick get away, fast climb, and high speed, and to have at the same time light weight, the ability to glide at a flat angle, and low flying speed to insure a great degree of safety in landing. To these qualities are added the item of moderate cost and ease of maintenance, high-grade construction and the pos- sibility of rapidly assembling and dissembling. The inventor had in mind the idea of presenting a ma- chine which would be of universal use for popular flying as well as for training. Careful attention was given to all details as dictated by the latest research and accepted good practice. That such things have been attained the demonstrations of its performances seem to bear out. On his first flight the pilot released the controls when an altitude of 1000 feet was reached. Perfect stability and high climb were observed. The throttle was full open. Without touching the controls, the throttle was retarded to diminish the power about 50 per cent, and the machine proceeded in straight horizontal flight. With the engine shut off the machine quietly disposed itself to a flat glide. Other tests of the machine's speed show that with full power, it is capable of 85 m.p.h., and by throttling the engine the speed can be reduced to 34 m.p.h. The value of this performance will be better realized when it is un- derstood that the Bleriot and Deperdussin monoplanes of similar horse power have a speed range of 40 to 46 and 40 to 48 m.p.h., respectively. Favorable comparison will also be found with a number of modern machines, both European and American, with 100 h.p. or more, which make an average speed of 70 to 80 m.p.h. In climb tests the Bellanca biplane ascended to 3300 feet in 10 minutes and 4600 feet in 14 minutes, with the engine throttled down to 1080 r.p.m., equal to 18 h.p. With the engine turning at 1080 r.p.m. the machine made a speed of 691/2 m.p.h. in three consecutive half- mile flights at a height of 15 feet from the ground. The speed mentioned was the average for the three flights. W T ith the engine increased to 1200 r.p.m., equal to 24 h.p., the climb of the machine increased to 530 feet per minute and the horizontal speed was 76 m.p.m. The climb was measured by means of a barograph and aneroid. In testing the gliding quality, the pilot began a glide from an altitude of 4600 feet at a distance of about ten miles from the starting point. With the engine shut off the field was reached and passed, and it was necessary to turn back and glide against the wind toward the field, adding two miles to the distance traversed. In this manoeuver a time of 8 minutes and 5 seconds elapsed be- fore the ground was touched. In this glide the machine was favored by a wind of 6 to 7 m.p.h. The incidence angle indicator showed that the machine was gliding at an angle of 5 degrees, which is equal to a ratio of 1 to 11.5. The above test shows that in case of a forced landing from an altitude of 4600 feet, the pilot will have ample time to select a landing place within a diameter of 24 miles. General Description Best selected white ash is used for the principal parts of wings, fuselage, landing gear, etc. Brazing and welding have been eliminated wherever possible. Care has been observed to avoid the piercing of longerons and other vital members. Safety Factor The factor of safety of lift stresses on the beams of upper and lower wings is 16, and the factor of drift stresses is 14. In the body and landing gear the safety factor of the weakest point is 12. Field tests have shown a high safety factor under difficult conditions. Even in snow 14 inches deep, the machine never met with difficulty in leaving the ground nor in landing. In diving and even in tail spinning tests, the machine was quick to recover itself, confirming the strength of sustaining surfaces. SIM, 1. 1. MOTOKK1) AKKOI'L. \.\KS n Assembling Facility In actual tests, tin- machine was dissembled in 1 /, min- nt.-s and re.-issciiihlcd ready to fly in -JU ininiitrs. This id in is expiditcd liy tin- employment of a -p. vial turn- bucklc, which can lie loosed and detached without losing tin- adjustment of tension, so that a simple \emeiit restores the attacliiilrnt of the cable with its original adjustment. General Specifications Span, upper pl.-inr .'(i ft. II in. Span, lower plain- ft. 6 in. Chord, upper plain- I ft. (> in. Chord, lower plane ..... .' It. t In. I ... I 40 sq. ft. th overall 17 ft. 7 in. Weight, iiini-hini- empty 400 Ills. I ''! l""l -' ,.373 II.-. Performances Maximum Speed. Minimum Speed IM N h.p.... [ 18 h.p in ft per hour) 83 76 70 34 M ixiiiiiim Cliint.iiiir Spreil per min.) fS5 h.p... . 830 I j^ i W [18 h.p ....... 330 Cli.linir \nglc ...................................... 1 to 11.3 Min. h.p. required for hori/. mtal Hight ...................... 6 Main Planes The dynamical stability of the planes is almost the same a- tin- Kitl'el :i-.'. It is most suited to high speed because of it- v.r\ small drift at small angles of incidence, and l.eeau.sc of the structural advantages afforded by the sec- tion. Spars are of ash, having a safety factor of 1 t. Struts between planes arc of streamline section of con- stant depth for two-thirds their length. Ends taper to the strut fittings. Controls Lateral and longitudinal balance is operated by stick control. The rudder is balanced; it is operated by tin- foot bar. Lateral control is obtained by warping the wings, and it- effect is so immediate as to require but a slight move- ment of the stick. Fuselage The fuselage is of good streamline form. Ita wooden I r mie i- of IM.X girder construction, braced hv cables from the pilot's eoekpit forward and with wire from the sam. cockpit rearward. The nose is co\ered with aluminium. a round door in on, side giving access to the engine. The reniamdi r i- covered with linen. do|M-d and varnislud. The front deck i- ..I veni.r. linen entered. The body tapers to a vertical strut edge at the rear, on which the rudder is hinged. No U.lts pass through the fuselage -pars, a simple ami light fitting making this possible. In front of the pilot is a dash, on which are found oil sights, clock, aneroid, inclinometer, and incidence angle indi- cator. Landing Gear The chassis i- of the ordinary V type, each V con sisting of two ash laminated streamline struts, joined to- gether by steel ami aluminium plates. Rubber shock ah sorbcrs bind the axle to the struts. Tail Group The empannage group is composed of a non-lifting fixed stabilizer, to which is fastened the elevator flaps. The attachment of the stabilizer is such that it is easily detached by removing four cotter pins. The rudder is of oval shape and is of sufficient area to insure complete control in handling the machine on the ground. Engine Group An air cooled .1 cylinder An/.ani Y type 35 h.p. is used. Its weight is 1*0 Ibs. Propeller 6 ft. 7 in. in diameter and 5 ft. 9 in. pitch. The engine is so attached as to form with the rest of the body a perfect streamline form with low head resistance. Only part of the cylinders are exposed, which are effica- ciously cooled by such a flow of air as obtained by a speed of 85 m.p.h. To ascertain the complete cooling of the engine, re- peated and accurate tests were performed. The engine was first tested on the ground, and after five minutes' run- ning, it was already losing 15 |>er cent, of its initial h.p. This loss was increasing as the engine continued to work. On the contrary when the machine was flying, such power loss was almost completely eliminated, for after from 40 to 6<> minutes of flight, no over-heating was ob- served. The Dellnnca Biplane in flight CURTI55 MODEL JN4-B MILITARY TRACTOR Scale of Feet -fe 86 SI\(;i.K MOTOHKI) .\KK01M..\.\KS K7 'II,.- well known Curtiss .INI, cuuippcd will. ,, Hispaiio-Sui/.a motor. This type of |.| lin r was used extensively for training pur- POM-S. It was originally powered with a Curtis OX s cylinder motor. Curtiss Model JN-4D Tractor Due to tlic f.ut that tliis machine has been widely used for training .m.ttnrs both IHTC and abroad, the JN tvpr i- prok-il.lv the la-st known of all the Curtiss models. It is comparatively \i\i[ and for its useful load carry- ing rapacity, is very compact. General Dimensions 'iii)r S|uin t'pper Plane .................. 43 ft. 7% in. in^r Spun Lower Plane .................. S3 ft. 11% in. Depth of Wing Chord ....................... 591^ | n . C.lp lietucell Wilier, ......................... 61% j n Stagger .................................... 16 in . Length of .Machine overall ................... .'7 ft. + in. Height of Machine overall ................... 9 ft. 10% in. AiiL'le of Ineiili-nee .......................... i degrees Dihedral Angle ............................. 1 ,|,.grec Swi-.-plm.-k .................................. decrees Wing Curve ................................. Kiffel y o . ,; Horizontal Stahiliier Anple of Incidence ____ degrees Areas ind's - fpper ..... ......................... 167.94 ^ f t . -I^'wrr ......................... 149. sq. ft. " s ( l'|'l'T) ........................... 35.3 sq. ft Horizontal Stahiliu-r ........................ 28.7 sq. ft. Verlieal Stahilizer .......................... 3.8 ,. ft. Klevators (each 11 (. ft.) ................... a sq. ft. Kiitlder ..................................... U sq. Total Supporting Surface .................... 352.56 Loading (weight carried |-r sq. ft. of support- ing surface ) .............................. 6.04 M.S. |MdlOf (per It. H. P.) ..................... 23.65 Ibs. Weights Net Weight Machine K.inpty ............... 1^80 Ibs. CirosN \\'ci)rht Machine and Load ........... 3,13() ll.s. I'seful I^,a. ilavillanil I- with a Sou h.j). Rolls-Royce en- gine, mid tin- adoption of tin- Liberty 12 has given the t iiitnl Stat.-s superior results in both performance and production. With slight modifications in its equipment, the De Havil- l.-inil t is used for reconnaissance, bomb dropping and tinhting. Complete night flying equipment is installed, consisting of .jrceii and red port and starboard electric lights near the ends of the lower plane, a rear white light on the deck just aft of the gunner's ring, and wing tip Han lights near the wing tip skids. Current for lighting and wireless is supplied by two generators attached to the inner sides of front landing gear struts. A camera is clamped to a padded rock on the interior of the body aft of the gunner's ring, where it i-. coineniently operated by the observer. Dual control is installed, and control stick is quickly detached and removed by pressing a spring catch when it is not neces- sary for the observer to take control. Hacks are provided for twelve bombs which are held in place horizontally under the lower planes, near the body. The release is accomplished from the pilot's cock- pit by means of bowden cable. A sighting arrangement is built into the body just behind the rudder bnr. Four machine guns are installed. Two fixed Browning guns are mounted on the cowling forward of the pilot, operated by the " C. C." automatic interrupter gear or the Nelson direct mechanism, which releases the trigger at each revolution of the engine crankshaft. Two mov- alile Lewis guns are carried on a rotatable scarfed ring surrounding the rear cockpit. A telescopic sight is provided for the two fixed forward guns and a ring and bead sight for the twin Lewis guns. Instruments carried are: Two gasoline pressure indi- cators, speed indicator, tachometer, altimeter, thermometer, clock, hand-pressure pump, inclinometer, map board, and compass. General Dimensions Put Span, upper plnnr 4.' t Spun, lower plane 4iJ3 ( 'liord, lK>th planes 4.*7 Gap between planes 8.0 Staffer li.6 Lrnirth over all 29.7 Height over all 10.84 Areas Sijuart fftt t'pper plane 916 Ix)wer plane 30i Ailerons (3 upper and 1 lower) 76 Totiil wing area with ailerons 4il Stnliiliwr 33.7 Elevator 833 Fin 4.1 Rudder U.4 Weights, General Pound* Murhine empty 2,**0 Ftn-1 and oil .' *4i Military load ** Total, machine loaded 3,7*0 Kstiin.il.il n-cful load 1,300 Weights, Machine Empty Pound* Engine * Kxhaust pipes Radiator and water 1 Propeller Gasoline tanks Oil tank Engine accessories, leads etc. . . . Fuselage with cowl 3"** Tail plane, Incidence gear Body accessories, seats, etc l'nd"ercarri(re ' " 90 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Front view of the De Havilland-4 with a 400 h.p. Liberty "12" Engine Tail skid Controls Wings . . Bracing Armament supports 11 21 460 68 88 Total 2,440 Military Load Crew Pounds 330 Armament 163 Bombs and gears 322 Photographic outfit 22 11 Total 848 Main Planes There is no sweepback, but upper and lower planes are attached to a center section and the body, respectively, at a dihedral angle of 174. Aspect ratio of both planes, 7.7. Angle of incidence, 3. Fuselage Veneer is used for covering the fuselage from the ra- diator to the gunner's cockpit, and no diagonal bracing is therefore employed in this part. The rear end of the body is constructed in the usual girder fashion, and the longerons, of spruce, are spliced. Veneer is used underneath the tail plane for covering the body. Tail Plane Attachment of the tail plane is such that its inclination can be varied from the pilot's cockpit during flight. Its front edge is hinged and the rear end braced by wires at- tached to a vertical post in the fin. By means of a cable wrapped around a drum and worm at the lower end of the post the rear brace wires are raised or lowered, and the trailing edge of the stabilizer is correspondingly raised or lowered, permitting the setting to be adjustable within the limits of 2 + 5. Engine Group The engine is a twelve-cylinder Liberty which develops 400 h.p. at 1,625 r.p.m. Bore and stroke 5 by 7 inches. Cylinders are set at a 45 V. Zenith carburetor and Delco ignition are used. Fuel consumption .54 }bs., and oil .03 Ibs. pr h.p. per hour. Fuel tanks are located at the center of gravity. Capacity 67.6 gallons. Oil tanks under pilot's seat have a capacity of 5.6 gallons. The radiator is provided with shutters operated from the pilot's cockpit, to cut off part of the cooling surface when flying at low temperature. Propeller, 8.6 ft. diameter and 10.7 ft. pitch. When at rest on the ground the propeller hub is 6 ft. in. above ground, and in flying position it is 5 ft. in. above ground. Performances Obtained by U. S. Army with the DeH-4 Endurance at 6..300 ft., full throttle 2 hrs. 13 min. Endurance at 6,500 ft., half throttle 3 hrs. 3 min. Ceiling 19,500 ft. Climb to 10,000 ft 14 min. Speed at ground level 124.7 m.p.h. Speed at 6,500 ft 120 m.p.h. Speed at 10,000 ft 117 m.p.h. Speed at 15,000 ft 113 m.p.h. Weight, bare plane 2,391 Ibs. Weight, loaded 3,582 Ibs. K .MOTOKKl) AKMOI'1.. \\KS Th, MrilM, Vfchei. ,,,,n,,,,.r,ial I, ,,, VJM.J - equipped with two HolK-Km,-, :<7 5 h.p. ,,!,... Two .-kpit placeil high in II,.- MUM- a srtin K raparily f.r 10 passengers in .s-pHrtc .inn rhiiir-. Knrl is rnrried for five hours; speed, 110 m.p.h. are rarrinl in Ihr The British Bristol Coup* biplane equipped with ^64 h.p. Rolls-Royce engine TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Line drawings of the D. H. 5 pursuit biplane SINGI.K MOTOHKI) A KI)1M.A\KS i.-mll,.ii.l ',. ,i,,,u,,,.. tl.r ,-,.,,,li;,r s t ,, Btri . r ,,f ,)- ,,,.,. . lrn , Ml ,,;,.,, f ; vt . s . Jli|ot widc rangr of vjs|(in The D. H. 5 Pursuit Biplane This in u liin. is a tractor biplan. with a single pair Chord, I.S7. 1 } m. of iiit. Mils;!.' M-ator tighter The De Havilland No. 5 Ordinary four-longitudinal typo, braced by cross wir- ing and strengthened in front, up to pilot's seat, and at rear near tail by ,S mm. plywood. Body faired to approx- imately circular section near front. The undercarriage is of V-type with solid streamlined wooden struts and a continuous axle. The tail plane is of one piece mounted at 1 incidence, without the cus- tomary incidence-change gear. The power plant consists of a 110 h.p. rotary Le Rhone, with main fuel tank for 100 lit. of gasoline and oil tank capacity of 21 lit. There is an emergency gravity fuel tank of 26 lit. capacity on upper starboard wing. The engine is fed from m.-iin tank by compressed air generated by small air pump. Total fuel supply for two hours' flight. The following instruments are mounted in the pilot cockpit: To right, two fuel supply pipes with stop cock-. and a change of gear for elevator control: on instrument board, tachometer, speedometer, altimeter, -.park switch, watch and compass; to left, fuel and oil throttles and a hand pump for the air. The weight of the machine is: Empty. U>1 kg., and fully loaded. 691 kg. Wing area is 20.1-1 MJ. m.. wing loading S-H kg. sq. m. and power loading ."'.;*, > kg. h.p. The Thomas-Morse S-V K Single Seater Advanced Training Scout, which makes a spwd of 11.' m.p.h. with an SO h.p. Le Rhone engine SIM. I I. MOTUKK1) AKKOl'l \\l - The Dayton- Wright D-4K. It has two uphol-tcrrd scats, huilt-in mahogany vanity ami lunrh boxrs, and x-vel platr mirror-;. It iil/ ? in. Stagger Length Height Angle of incidence Dihedral of lower plane Stabilizer incidence Weight unloaded 4T(i 11)s Weight loaded Horizontal maximum speed 85 m.p.h. Landing speed :?T m.p.h. Climb in 10 minutes Engine, air-cooled De Palma :!T "-P- The engine is a 4-cylinder air-cooled " V " type manu- factured by the De Palma Engine Company of Detroit. Its weight is 3.7 Ibs. per h.p. The engine consumes 4 gallons of gasoline per hour and tank has a capacity o) 12 gallons. Oil is carried in the crankcase. AYTOX-WRIGHT T-4 "MESSENGER" I Lower right wing strut socket, showing pulley for aileron cable fitted into the leading edge of the wing. 2 The strip veneer used for cross bracing on the interior of the fuselage. 3 Attachment of upper wing section to the center section. 4 Ele- vator control lever. 5 Landing chassis fitting snowing the streamline aluminum casing for the shock absorber cord. BEQCKMAN5 IOO HP G.V CNOMt SPEED SCOUT 3cU of F.,l McLuhim 98 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Side view of the Berckmans Single Sealer, equipped with a Gnome motor of 100 h.p. In a great number of points, the little single-seater, designed by Maurice Berckmans, shows a marked advance in scout-building which has resulted in some perform- ances worthy of note. This plane has ascended to 22,000 feet and returned to the eartli in twenty-seven minutes. Its normal climb is 1100 feet per minute. These figures were verified by an altimeter (indicating barometer) and two recording barographs. Quick climbing ability is but one of the inherent features of its design. The streamline monocoque body, the reduc- tion of exposed parts and the light total weight have as- sisted in the achievement of high speed. A judicious dis- tribution of weights and areas, bringing the centers of area, thrust, gravity and resistance in advantageous posi- tions, has made the machine easy to control and prompt and precise in response to control movements. These at- tributes, together with its neat details and finish, make this scout one of the fine American machines of this type. General Specifications Span, upper plane ' 26 ft. in. Span, lower plane 19 ft. in. Chord, both planes 4 ft. 11 in. Gap 5 ft. 3 in. Stagger 17 Length of machine overall 18 ft. in. Height of machine overall 8 ft. 9 in. Net Weight machine empty 820 Ibs. Gross weight machine and load 1,190 Ibs. Useful load 370 Ibs. Engine, G. V. Gnome 100 h.p. Speed range 115-54 m.p.h. Climbing speed 1,100 ft. per -min. Gliding angle 8 to 1 Radius of action 2% hrs. Main Planes The upper plane is in two sections with a 1 dihedral; lower plane in two 9 ft. 6 in. sections with a 2 dihedral. Angle of incidence of both upper and lower planes, 2.1; 1.5 at tips. Stagger, 17, amounting to 16 inches. No sweepback. Area of the upper plane, 10.6 sq. ft.; lower plane, 77.9 sq. ft. Total supporting surface, 184.S sq. ft. Loading, The Berckmans Speed Scout or weight carried per square foot of supporting surface, 6.4 pounds. Wing curve, Eiffel No. 32. Ribs have I/., in. by 8/16 in. spruce battens and veneer webs. Veneer is with 3-ply birch-gum-birch, each lamination 1/16 in. thick. Ribs spaced along the wing 10 in. apart. Leading edge and the forward main wing beam are of spruce, and the rear beam of ash (the ash being necessary because of the relatively narrow depth of the Eiffel wing section at the rear spar). The trailing edge of 20 gage aluminum tubing with an outside diameter of % in. Ailerons on the upper plane only, 4 ft. 10 in. in span and 1 ft. 11 in. deep. The half-round leading edge is set into a curved recess in the rear wing beam, leaving no opening between these surfaces. Interplane struts are of spruce, hollowed for lightness. The halves are glued together with fiber crossed (for avoiding warping) and bound in three places to keep them firmly in place. Maximum width, 1^4 i n -> maximum depth (at the center), 4 in., tapering to 1% in. at the ends. The front edge is nearly straight and the rear curved in a pronounced gradual taper. Wiring between the planes is with flexible stranded cable; flying wires doubled and bound together to lessen resistance. The compensating control cable, from one aileron to the other, is run concealed in the upper plane. Inspection doors are located above the pulleys, where the cable ends emerge and run to the aileron king-posts. Body The fuselage is of the monocoque type, with a finely tapered streamline form. Its section at all points is per- fectly circular; at the forward end it is 3 ft. in. in diameter. It is built up of 3-ply spruce, except the por- tion from the pilot's seat to the engine, which is 4-ply. Laminations are 1/16 in. thick, with coarse 1/16 in. mesh fabric interposed to keep the glue from shearing. A headrest and streamline former is built onto the fuse- lage top aft of the cockpit. At the points where landing-gear struts and interplane flying cables are attached, the body is braced with rings SlN(;i.K MOTOKKI) AKUOl'I.AM.s M of 1/1(5 in. thick I' chaniK 1 steel, meted to tin- int.-rior wnll. MI. l control is installed: the stick for loBgftndiaa] nnti 1-iteral inn\ i MK -iits. :iiul tlic foot -li.-ir fur ilircrtinn. Tail Group I.ijj!. 1 - 1 tubing is used in tin empen- nage construction. Tlic tixed tail plane is srt at a neutral anijlc. It is in two halves, attached to cither si rnl ;ittrui|>ts have lit en made for years by experi- menters to perfect .'in aeroplane with flexible in^s. or following closely tlic tli -\iliility of tin- wings of a bird. The biplane designed li\ Dr. \V. \\' . Christinas ap|)<-ars to II.'IM- met with Miiich success in tin- structure mentioned, and liis tlu-orics of Hexing wings h.-i\e shown more prac- ticability than most rigid-wing :idln rents were apt to bc- lic\e possible. A most radical departiin- from what has heretofore been believed to lie incessarx practice is the entire elimination of struts, cable*, and wires in the bracing of the wings, as well is tin absence of wiring ill the internal structure of the wings. The wing curve is one developed by Dr. Christmas, and is of fairly deep section between the main wing beams, but tapering oil' sharply aft of the rear beam, anil merging into a Hat. thin, flexible, trailing edge. The cH'cct of the section is to maintain a high angle of inci- is til-- machine is traveling at low speed, and a lnyli angle as the machine gathers speed, flattening out the wing and presenting very little resistance. I'ppcr and lower wings have the same aspect ratio. I pp. r wing has a thickness of 5 inches. Patents are pending on the wing construction, and full details cannot now be gixcn of these features. With the wing section used. Dr. Christmas has sue < < ded in obtaining a 7- per cent, lift on the upper wing, a higher vacuum than found on any other section. Wings set at an incidence of .S'.j degrees. \- the wings are not braced transversely, flexibility is also obtained in that direction. I'litl's of wind, or sudden changes of direction, do not sharply afTeet the machine's >r the shock is transmitted only after being ly alisorlx-d by the resiliency of the wings. It would seem that such construction would result in a low factor of safety, but the designer claims a safety factor '.ii throughout. When at rest on the ground, the wing droops in a nega- tixe dihedral of - - 7 degrees. In flight the wing tips i range of flexibility of 3 feet; that is, the wings can assume positixe or innatix. dihedral measuring 18 inches from the hori/.ontal in cither direction. It has I..,,, demonstrated Hint the wings carry a load O greater than me. ssjrx to sustain the machine in Hight. nd this load i> carried nuardhss ,,| wind pull's or extri -trains due to increased wind pressure above or In-low lh wmn. I'he principal specifications of the Christmas "Bullet" i"i!ow s |MT plane i ft. (I in. Chord, lower plain- .' ft. li in \n-a, upper plan.- 140 M]. ft. \re.i. lower plnnr 30 st\. ft. length overall .'1 ft II In. \\i-itrlit. in.u-liiiM- einptx M.tl Ids. Weiirht. fully lonilcd ." :.loo llw. Miiiiiiiiini s|M-etl iO-60 m.ji.li. M ixiiinim speed 174 tn.pji. Cruising radius iiO milr^ Oiling :u,7oo f|. A Liberty " (! " is used, giving 18.') h.p. at I KID r.p.m. : the machine attains I7e, copper mesh screens cover in the sides and top of the fuselage, forward of tin- wings, and this surface has proven adequate for the Lib- erty " (i." Much of the radiation is thereby effected by- skin friction rather than by dead head resistance. The propeller has a 10 ft. 6 in. pitch and in 7 ft. 6 in. in diameter, designed for a speed of 195 miles an hour, which the machine is expected to make with full power. 102 TEXTBOOK OF APPLIED AEROXAUTIC EXGIXEERIXG LAWSON M.T2. T R ACTOR SINGLE MOTOKKI) AKHOI'I.AN I - HIM The Law-son M. T. .' tractor biplane The Lawson M. T. 2 Tractor Biplane Tin characteristics of tin- M. T. 2 nre Approximately as follow * : S|.:in. upper plain- Sp.lll. low IT plane ;t'l ff. Mi ft. .-, ft. J in. 5 ft. 1 in. 8 In. tt . upper plane (iiicliiiliii)! ailrroiis) ........... >00 si|. ft. . IIIUIT plane ............................... 1.X) sq. ft. Lrnjrth. over nil ................................. 25 ft. Hcittlit, OMT all ................................. 8 ft. -lit. rmpty ................................. 1,200 His. \\.-i_-M. L.Mlecl Speeil ranj:e Clinili. in In minutes Clidinjr anjrlr. full load Motor. II ,11 Scott 1,900 His. 4."-90 tn.p.h. 6.0(X)ft. 1 in 9 100 h.p. Planes Both wings are in two sections, tin- top attaching by hiiii-i - to hinge ]>lii);s secured in the cabanc and the lower to plnn-, secured to fittings and cross tit- tubes in the fuselage. Tin- spars are of 1 section, having a high factor of >y (which incidentally is carried throughout the ma- rhinc on the more important parts). They are left solid at both internal and external strut attaching points and also wherever any bolts attach such as for the wing and aileron hinges. The ribs themselves are built of wood webs, reinforced with strips between lightening holes, and cap strips. Mahogany veneer forms the nose of the upper surface of both wings while false ribs are placed between the standard ribs from the entering edge to the front spars. Between spars the ribs are braced by stringers while bays are separated by square section struts channeled out. Double wiring takes all drift strains while single is used for truing up. These wires are given two heavy coats of red lend while all woodwork is given a coat of filler and a coat of varnish. Tin- ir nlniL' edge is ash, excepting at the inner ends of the wings and outer ends of the ailerons where flattened 1 tubing is used. The outer edges are of steamboat white ash and slightly curved in plan view to take the tensionnl pull of the cloth caused through the contraction of the wing dope upon its application. Both wings are connected by two pairs of interplnnc struts on each side of the fuselage. These taper into cup sockets which arc fastened to the wing strut plates by a neat bolt and nut. The plates theniseKes are of the four bolt type whereupon the bolts clamp the spars and are prevented from sliding by blocks attached to the latter. The lift cables arc all doubled and are all of 1/s cable with the exception of the main lift and main landing wires, these being .1 The ailerons work in conjunction with each other, being interconnected by cable guided through neat fairleads on top of the upper wing. Each is equipped with two sets of brace arms provided with shackles to take both brace and control cables. The control cables run through pul- leys down to the fuselage where they connect to a chain and arc safetied to each other as well. Fuselage The longerons and vertical struts arc of straight grain ash in front and spruce in the rear. The longerons are left solid their complete length, while all struts, both ver tical and horizontal, have been channeled but left solid at all points of connection. Steel tubes fitted into sockets are used for horizontal struts back to the rear pit and also to carry the load from the tail .skid shock absorbers. Owing to the constant section of both longerons and struts in the rear part of the fuselage the fittings are all standard and can be used at any of the stations in this section. The stern post is of tubing witli interchangeable fittings at upper and lower ends to take the longerons. Each pit is reinforced with ash rims as well as the tension wires to prevent any twisting effect caused by rapid manoeuvcring either on the ground or in the air, and it likewise acts as a protection in case of a " telescoping " landing. The whole fuselage is braced throughout by double cables in the front sections and wire in the rear. The engine bed rails rest on top of an ash cross-member and are secured to this by U-Bolts. The whole unit is braced by tubes fitted with plug ends. 104 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Gallaudet E-L 2 Monoplane Striking originality in design is shown in the twin- pusher monoplane exhibition by the Gallaudet Aircraft Corporation. Mr. Gallaudet's 1919 Sport Model has a high factor of safety and is easily maintained. Two stock " Indian " motorcycle engines are located in the nose of the fuselage, connected to a common trans- verse shaft and resting on the top of the plane, and driv- ing twin pusher propellers on longitudinal shafts driven by bevel gears. Engines are " oversize " models, giving 20 h.p. each at 2400 r.p.m. Weight, 89 Ibs. each. Propellers are 3 bladed (2 bladed propeller on exhibition), 4 ft. 8 in. in diameter and 7 ft. in. in pitch. Propellers run at one- half engine speed, 1200 r.p.m. The plane has a span of 33 ft. in. and a chord of 4 ft. 6 in. Wing tip ailerons are 7 ft. in. long and 1 ft. in. wide. Wing section, modified R.A.F. No. 15. Di- hedral, 178. The body is of monocoque construction, 3-ply spruce being used. Two seats are provided, side by side, with single stick control. Tail areas: Fin, 2 sq. ft; rudder, 4; stabilizer, 12; elevators, 8. Overall length of machine, 18 ft. 7 in. Special pat- ented true streamline wires brace the wings. For adjust- ment and dissembling a rod from one cabane to the other permits slackening of the cables and removal of planes without loss of adjustment. Turnbuckles are therefore unnecessary. Eight gallons of fuel are carried ; sufficient for 2 hours. With full load, a speed of 40-80 m.p.h. is attained. At present the machine weighs 750 Ibs., but new features will permit a reduction in weight to 600 Ibs. The small Gallaudet twin-motored monoplane. It is powered with two motorcycle engines. Its size can be estimated by com- parison with the seaplane above it. The Gallaudet E-L 2 " Chummy Flyabout " Monoplane 1 Formation of the Gallaudet streamline cables. 2 How the upper part of the landing wheels are fitted into the monocoque body. 3 Right hand shaft drive from the engines to the pusher screw. 4 Bevel gear housing, connecting trans- verse driving shaft with the longitudinal propeller shaft. 5 Attachment of bracing cables at the cabane. IE PEBE FIGHTER 400 HP LIBERTY 12' MGINE i ' V I 106 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Side view of the American- built Le Pere Fig'hter, with a 400 h.p. Liberty Engine The Le Pere Fighter Captain G. Le Pere, an aeronautical engineer in the French Air Service, designed the " La Pere Fighter " with a Liberty engine. It was intended for use as a fighter or reconnaissance plane. General Demensions Span, upper plane 39 ft. Oy 4 in. Span, lower plane 39 ft. 0>/ 4 in. Chord, both planes 5 ft. 6 in. Gap between planes 5 ft. 0% in. Stagger 3 ft. 01% in. Length over all 25 ft. 4% in. Height over all 9 ft. 10% in. Weights Pounds Machine empty 2,468 Pilot and Gunner 360 Fuel and Oil 475 Armament 352 Total 3,655 Performances in U. S. Army Tests Height Speed Time of Climb (feet) (m.p.h.) (min. and sec.) 136 min. sec. 6,000 132 5 min. 35 sec. 10,000 127 10 min. 35 sec. 15,000 118 19 min. 15 sec. 20,000 102 41 min. sec. Ceiling, or h sight beyond which the machine will not climb 100 feet per minute, 20,800 feet. Main Planes Planes are flat in span and have no sweepback. Top plane is in three sections ; a center section over the body, and two outer panels. Lower plane in two sections at- tached at lower sides of fuselage in the usual manner. Upper and lower planes are similar in shape, and with ailerons 21% in- wide by 9l!/4 in. long attached to both. An interconnecting streamlined rod is used between each pair of ailerons, located behind the outer wing struts. Leading edge of upper plane is located 49 9/16 in. from front of propeller hub. Middle struts located 9-1"% in. from center of machine; outer struts, 98l/o in. from mid- dle struts; overhang, 41 in. Interplane strut design is unique inasmuch as it eliminates the usual incidence wires. Fuselage Veneer is used for exterior finish. Over all length of fuselage, 22 ft. % in. Maximum section at the gunner's cockpit, 32l/> in. wide, 45l/o in. deep. Center of gravity occurs at a point 6 ft. 3 in. from nose of fuselage. Axle of landing gear 22% in. forward of center of gravity. The landing gear wheels have a 6~> 9/16 in. track and are 28 in. in diameter. Tail Group Over all span of stabilizer, 98% in.; chord, 3 5 1/, in. It is fixed at a non-lifting angle, and attached to upper fuselage longerons. Tail flaps or elevators measure ISS 1 /^ in. from tip to tip. Their chord is 31% in., and in addition to this there are small balancing portions extending beyond the tail plane. Rudder is 30 in. wide and has a balancing portion above the fin, 25 in. wide. Three quarter rear view of the Le Pere Fighter SINCil.K MOTOKKI) AKHOIM. \M.S KIT It dcXrlops in.; wci-jlit. Two /enilh Engine Group \ I lIl.Tty " I'.' " II 10 h.p. engine IS lls.d. HH h.p. at \~:> r.ji.in. Horc. :. in.; stroke. without propeller and w it. r. s;,.s pound*. Duplex carburetors an us. d. The radiator is lm-.il.il in the ii|i|n r pi nn center section. anil its liN-atiiui has in 1-1 ssil.it. rl sonir slight iiinilitii-.itions in tin- rnjiini- to inrn-.isi tin \\ati-r i-irriilation. 1'roin-llcr. ! ft. t in. in iliaindi-r. 1 runt |in)|M.*ller pl.-itr proju-ts ll :; , in. forw.-inl of fus, l.i^, ,,,, . I'mpt Ili-r .-t\is I.'. 7 hi in. In-low lop of npprr lonnrroiis. In Hyiiij; position tin- 'irop. lli r hull is .'. ft. ,' ; s in. alnnr tin- unniixi linr; \ilnn it n-st on tin- Around tin- propi-llrr hull is li ft. | :: N in. aliow ground. Left- h*Ml*. Tin- Irti-ion of Hi.- ri-nr brace wires lit oirri<-rn>ti>ifr lr\rr, sliowinjr the means for adjiistmrnt in UK- u||M-r end of forked trrininal. Ordnance Engineering Scout 80 LeRhone This m.n-hine was tested at Wilbur Wright l-'ield by the I'. S. A mix Climb (ft.) Summary of Results Time Kate r.p.m. Speed r.ji.m. o 98 l. l-o <> min. 535 1.1 Hi 9i l.i;> 10.000 ]T min. :U) sec. 31 . 1,100 84 1,175 15,000 55 min. 1,100 70 1,100 Service ceilinfr 13^00 ft. U .-iirht. empty s:i", |b-. Total weijrht of load i ll)t. Total weifrfit 1,117 Ibs. Ordnance Scout with M Ix-lthone Ordniince Scout with -n |.,-l(h..n.- Ordnance Scout with 80 I-elMnm. Ordnance Scout with THE Of .C " B 160 HP GNOME SINGLE 5EATER Scale of feei Mclaughlin 108 SI\(;i.K MOTOHKl) AKKOIM.ANKS I line quarter front \iew- of the ( ). I ( Mnjle Srili-r Seoul Itiplalie The O. E. C. Types B and C Single Seater Tin type " ( " i- .in .iil.-iiit.-itiun of the Model "B" filthier. .-UK) with tlir e\re|>tinii that the staggers differ iti tin- two type- ind tin- t.-nik-. .-mil weight distributions are p in. lower pl.-ine ........................ i3 ft. In. Chord, II|>|MT plum- ...................... 4 ft. O in. Chord. IIIM-IT filiuir ....................... ;{ ft. ft in. Cup. In-twi-fii pliitK-N ...................... 3ft. Sin. (K.-r.ill IniL'tli ........................... 19ft. in. Ovrnill hcijilit (pn.|x-ll.-r hiirizimtal) ...... 7 ft. 7 in. -IT ................................. 7 in. Areas pl.inr l.nwrr pliinr .................................. 77.H Ailrriiiis, np|T pliinr ......................... 175 Total wing area (with Hili-nins) ............... 180. Kin Huildrr 3.08 5.4 Weights Mixlrl It .M.Hl, I C 1 1 weight, full liuifl .............. 1^90. 1.090. Wright ]M-r M|. ft. degrees. Chassis designed to stand up when fully loaded ma- chine is dropped from a height of 10 inches. Fuselage Length of fuselage, 15 ft. 11 in. Maximum section, 3 ft. 5 in. by 3 ft. 5 in. Fuselage designed to stand a load of 30 pounds per sq. ft. on horizontal tail surface and dynamic loading of 5. Engine section has a safety factor of 10. The instruments on the dashboard are as follows: Dixie Magneto switch; Phinney-VValker rim wind clock; longitudinal inclinometer; horizontal inclinometer; Alti- meter (20,000 ft.); Tachometer, Signal Corps, type B; and a Sperry Air Speed Indicator. The clock, Altimeter, Tachometer, and Air Speed Indicator have Radiolite dials. A Pyrene fire extinguisher is conveniently mounted at the left of the seat, connected so as to be pumped directly into carburetor, or it may be used separately. Power Plant (LeRhone) The 80 h.p. Le Rhone engine develops its rated h.p. at 1200 r.p.m. Fuel tanks are mounted between the engine and the pilot, over the center of gravity. Capacity of gasoline tank, 18 gallons, Oil, 4 gallons. Weight of gasoline, 110 Ibs., sufficient for 2*4 hours. Weight of oil, 28 Ibs., sufficient for 2% hours. Gasoline consumption, 0.60 pounds per b.h.p. hour. Oil, 0.13 pounds. Propeller, 8 ft. 4 1 /. in. diameter and 7 ft. 6 1 /-; in. in pitch. Height of propeller axis above ground with machine in flying position, 4 ft. 11 in. ; with machine at rest, 5 ft. 6 in. Power Plant (Gnome) The Gnome engine is of French manufacture. At 1200 r.p.m. it is rated at 160 h.p. Gasoline consumption, .85 pounds per h.p. per hour; Oil, 16 pounds per h.p. per hour; Gasoline capacity, 35 gallons; weight 210 pounds. Oil capacity, 4 gallons; weight, 28 pounds. THE MARTIN 45 HP ABC ENGINE KDI SCOUT Scmim tf F..I Mclaughlin 111 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Martin K-III Single Seater with a two cylinder Gnat A. B. C. engine devel- oping 45 h.p. The Martin K-III Single Seater Some of the distinctive features of the Martin K-III, 15 h.p., single-seater, are retractable landing chassis, the K-bar cellule truss, wing end ailerons, and shock-absorb- ing rudder, which have been patented by Captain James V. Martin, the American aeronautic engineer. These fea- tures are interesting solutions of difficult aerodynamical and constructional problems and show the tendency of modern design toward the attainment of efficiency with low power rather than the employment of great power to overcome the disadvantage of uncertain design. The K-III was designed as an altitude fighter, and is equipped with oxygen tanks behind the pilot's seat and provision for electrically heating the pilot's clothing. The seat is so located that excellent vision is obtained; vision vertical circle from dip of , r > dead ahead through an arc of 180; horizontal circle 360, transverse circle from dip of 27!/2 through an arc of 235. The machine can light upon and start from a country road and can travel 22 miles on one gallon of gasoline, making it an economical means of carrying mail and light express in rural free delivery, etc. Dimensions Span, upper plane (without ailerons) 15 ft. in. Spun, lower plane 17 ft. 11% in. Chord, both planes 3 ft. 6 in. Gap between planes 4 ft. fi in. Length overall 13 ft. 3'/ 2 in. Height overall 7 ft. 4% in. Areas (Sq. Ft.) Upper plane (without ailerons) 53.50 Lower plane 47.80 Ailerons 5.00 Stabilizer 9.50 Elevators 6.66 K udder 4.88 Weights (Lbs.) Engine 85.50 Wings 60.75 Ailerons and supports 9.50 Chassis and retracting mechanism 16.38 Wheels 17.50 Struts, wires and K bars 8.25 Oil and gasoline tanks ................................. 9- 7;> Rudder and tail skid ................................... 7 - 75 Damper and elevator .................................. 14.50 Fuselage, complete .............................. Propeller and hub ..................................... 13.63 Total weight .................................... :550 - Performance (Estimated) Altitude (Ft.)' Time.(Min.) Speed (m.p.h.) 5,000 10,000 15,000- 20,000 25,000 3 6 11 18 28 speed 145 135 113 HI 108 07 m.p.h. at 10,000 (With 60 h.p., 100-lb. engine feet.) Endurance at 10,000 feet: At full power ..................... 223 miles At minimum power ............... 216 miles Main Planes The planes have neither stagger nor dihedral. The aerofoil of main planes is known as the " Ofenstein 1." At 10 m.p.h. the Ofenstein wing section has a lift- drift ratio of 22 to 1. Upper plane is in a single continuous span. Wing ends are at right angles to the leading edge, and are finished off with a semi-circular termination which varies in radius as the wing varies in thickness. The half-round wing ends are characteristic of all the aerofoils of the Martin K-III. Principal wing spars for main planes are centered 14l/> in. back of leading edge, where the trusses carrying the lift are direct instead of bridged between the ribs. The front of main wing beam is coincident with the most forward travel of the center of pressure. The lower plane is in two sections, and attachment made to the fuselage. Wing ends are raked at an angle of 1 5 degrees. Interplane bracing is of the " K-bar " cellule truss type. The head-resistance is reduced 4 per cent through the elimination of struts and wires. SINCil.K MOTORED .\ KHOIM.ANKS 113 1 unit \ i< ui tin- Martin Kill Scout, l>y C.i|it.iin .1 inn s \'. Martin, -mil comprising sonic of DM- special Martin feature-. The holding jrrnr is shown in it-, retracted position The percentage nf intfr i-i llule interference with the K-bar truss is \S -is i-mii]i:iri >1 with -'.'' '< in tin- standard truss; a total reduction of Hi' I. Of this reduction. 16% is due to tin- cliniiii.-itiiin of struts and win-s while- -i\''/c, is due to the increased gap obtained without subsequent weakening of truss or increase of structural resistance. K ^Iruts centered 1 t ft. from one another. The vertical member is ^ ft. .'('^ in. long; greatest section. I 1 t ill. by I 1 , in. The angular members of K-struts are attached to rear wing beams located 18 in. back of main beams. These members are of steel tube faired with sheet aero- metal. The vertical member of the strut is not subject to any bending moment at the juncture of the inclined members, for the upper member is in tension and the lower in com- pression, thereby neutralizing the forces at that point. The mid-strut fitting is designed with a view to equalizing the moments and relieving the vertical member of all c\c< pt the usual direct compression. l-'lying and landing wires are .3 16 in. diameter. Cen- ti r se.-tion .TOSS bracing is with ' s in. diameter wire. Tin- wing-end ailerons are an unusual departure from customarv aileron disposition. They have n righting influ- ence per square foot of area of t to 1 with the added advantage that they do not impair the efficiency of the aerofoil to which they are attached. The ailerons have a symmetrical double convex surface and are so balanced that their operation requires very little effort Ailerons are operated by means of a sliding rod running through the upper plane. Two cables running up the center panel struts cause the rod to slide from side to side. At the wing ends, the bar fits into a tubular collar attached to the ailerons. The collar is provided with a spiral slot or key way through which a pin from the rod projects. The sliding movement of the rod causes a rotary move- ment of the aileron collar. This method does away with all exposed actuating meml < rs. Fuselage Overall length of fuselage from engine plate to rear termination. 1(1 ft. 10 7 1(5 in. Maximum depth. X ft. (H, in. (not including streamline head rest); maximum width. -.' ft. -!'* in. The center of gravity is located 2 ft. 7 ' i- in. back of the engine plate. Veneer of ply-wood is used for the internal construction of the fuselage. In flying position, the top of the rounded turtle deck is practically horizontal. The upper longeron-, as well as the lower have an upward sweep towards the rear. The fuselage terminates in a vertical knife edge 18 in. high. Internal bracing of the fuselage is with solid wires looped over clips at the ends of cross-bracing members. Wires are run in series of four each, grouped in ribbon form. Each wire has a tensile strength of 2."it> Ibs. each; at the cross-braces, they run over a :< Hi in. radius. Only eight groups of wires and eight turnbuckles are required in the internal bracing system. The cowling and propeller spinner are of " aeromet.il. having the tensile strength of sheet steel at one-third of the weight of steel. Where engine cylinders project from the body, half- conical formers carry out a streamline. The fuselage is designed to stand a load of I OS Ibs. per sq. ft. of horizontal tail surface. Factor of safety, six. Instruments carried are: Altimeter, tachometer, gaso- line gage and oil gage. Tail Group The horizontal stabilizer has a span of 7 ft. 6 in. and width of 2 ft. (> in. Ends are raked at a 15 angle. The stabilizer is located in line with the center of thrust. It is fixed at a non-lifting angle and supported from below by a pair of steel tube braces. Elevators are 12 in. wide and have an overall span of 114 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Engine mounting, Martin K-III Three-quarter re;ir view of the Martin K-III fuselage 7 ft. 10 in. For rudder clearance, the inner ends of elevators are raked 30. Rubber covering between stabilizer and elevators closes the gap between the surfaces, giving a smooth, unbroken outline. There is no fin. The rudder is provided with balanced areas above and below the fuselage. The tail skid is contained within the rudder. It is pro- vided with rubber elastic shock-absorbing cord similar to the customary practice. It is especially effective when taxying on the ground. The combining of the rudder and tail skid does. away with considerable weight and air resistance while adding to the effectiveness and simplicity of the construction. The rudder is 1 ft. 10 in. wide; maximum height, 3 ft. 5 in.; balanced portions project 8 in. forward of the prin- cipal rudder area. Flexible 3/32 in. cable is used for operating the rudder, by means of the usual foot bar. The elevators are actuated by means of a single % in., 20-gauge steel tube from the control stick to a lever pro- jecting downward from the center of member forming the elevator leading edge. The fuselage terminates beyond the elevator leading edge, providing space for the enclos- ure 'of the operating lever. Landing Gear Ackerman spring wheels are used for the landing gear; these have 2 in. tires, and are 20 in. in diameter. The two wheels weigh 17 1 /' ^ )s - Wheel track, 2 ft. 5 in. When the chassis is extended, the underside of the fuselage at the forward end is raised 2 ft. 3 in. above the ground. When drawn up during flight, only the wheels are exposed. The front of axle and the two forward struts have flat front faces, so that when in flying position, these members fit flush into the fuselage bottom. A hand-operated worm gear, operated during flight, causes the chassis to be retracted with practically no effort on the part of the pilot. The landing gear has a factor of safety of 20. Engine Group The power plant consists of an air-cooled two-cylinder opposed " Gnat " A. B. C. engine, developing 45 h.p. at 1950 r.p.m. Fuel consumption, .56 Ibs. per h.p. per hour ; weight, 50.4 Ibs. Oil consumption, .017 Ibs. per h.p. per hour; weight, 1.55 Ibs. The fuel tank is located in the upper main plane above the fuselage. It has a capacity of 9.03 gallons, sufficient for a flight of two hours. SIX(iI.K MOTOKKl) AKKOIM.. \.\KS II.-) .ni Itipl.ini-, wilh -peri i! - cilinilcr I'.i.k.ird a\i.iliH.~, li>s. I in-1 consumption. ..',0 to .,U ll>s. per h.p. hour at sea level. Weights, Areas, etc. AreH, main plam-s 387 q. ft. Wright, innehinr <-in|ity . I^.Hl Ills. Normal flying wi-ijjlit ' .'.Hi; Ills. \\'ri)rlit. Ihs. |-r h.p l:..i His. Winfr lomliiijr, p<-r sq. ft .i.i> M". IVniiU~il.il- i-\tra luggage HXI Ihs. Altitmli- Performance (Estimated) Tim, of Climb (ininulc- ) Spi-i-il (m.p.h.) 101 100.5 9 15,000 (>o> Absolute ceiling, 19,500 feet. 34.5 I- ui-l rmifre (hrs.) :< U 4 SO.MK DI-.TAII.S OK TIIK I'\(K\HI) T\V(> SKVIT.lt Tit ACTOR I Tlx- shiM-k alisorlx-r arninp-mrnt. Thf axle is sqniirr, where it run* in the chassis slot. The elastic conl is iliviili-d into two (rron|is. one fore nml one nft of the nxle. i? The roomy suit ras ( - Iwker coinpnrtment Ix-himl the pilot's seat. A i, with ilov.-taiU-o 1 nlgrs tits IIMT tin- op<-nin(f. '.I Donlih- stilling cover plates an- ns.-il to |>rrmit rsy access to the unih-r >f tlx- engine in the vicinity of the air intake, projecting through the fnsrlnjn- Uittoin. 4 Wing construction. Webs are of thin mali,ii:.iii\ vi-ni-er. Cap strips anil triangular section |i-ailing edge of spruce. Short false rihs run from leading edge to main front heam. 5 Tail skid and anchor plate for stabilizer braces THE '5TANDA&D' M GNOME OR LERHONE ENGINE SECONDLY TWINING PLANE of /eel 23*5 116 SIXC1.K MOTOKK1) .\KKO1M..\\KS 117 Hi. Standard Model K-l Sing "II ll |>. I I- Kllollr rll^ilir. The Standard E-l Single Seater Height (l-Vet) 8,500 10.000 Summary of Performances (Continued) (With 1..- Hhone Kngine) Time of (limb Hi min. 30 s.v. -'-> min. 30 sec. II at.- of Climb Kt. |MT mill. 900 Speed (m.p.h.) 90 85 (Viling, 14,500 feet. Stalling speed, 48 m.p.h. (Hiding angle, 1:7. Maximum range: At 5,000 ft., iOO miles; 10,000 ft., 160 mites. Tin " K I " Single Si.-itir was designed ; i s : , si-condary training machine. It is provided with either an 80 h.p. I ( Itlione or a 101 h.p. Gnome engine, but in either case the dimensions of the machine remain Ihe same. Tin- It. A. I'. No. I .'P wing curve is used. Dihedral. X r /i : aspect ratio of both planes. 7; stagger, 13.02 in. There is no sweepliack nor decalagc. Wings are set at an angle of 2 to the propeller axis. Maximum diameter of fuselage, K''-j in.; fineness General Dimensions Power Plant Feet (Lf Rhone) s l'" n - "PP" P' am> ** Span, lower plane 94 Tin- I..- Khonc is a nine-cylinder, air-cooled rotary en- Chord, both planes 3.5 gine developing 80 h.p. at 120O r.p.m. and 8 I h.p. at 1290. Gap between planes 4 More and stroke. M Mi in. by .1 ' .. in. length over all ...18.85 I'll, I tank located near center o*f gravity, has a capacity of 20 gallons. Fuel is consumed at the rate of .725 Ibs. . P-T h.p. per hour. Square feet Oil tank, located below fuel lank, has a capacity of 3 t'pper plane 81 gallons. Oil is consumed at the rate of .03 Ibs. per h.p. Ix>wer plane 7J.: per hour Ailerons (J upper and J lower) 93.2 Total wing area with ailerons 1533 (Gnome) Stabiliser 19 The nine-cylinder rotary Gnome, manufactured bv the * levator 19.7 " * I** in -J fl General Vehicle Company, is known as tv|>e B-2. At .. I -i'ii r.p.m. it delivers KM h.p. Bore and stroke, 110 mm. by l.'.d mm. Summation of Weights Fuel tank has a capacity of 29.5 gallons; rate of con- (With !.< Ithonc Kngine) sumption. .81) Ibs. (>cr h.p. per hour. Wright in Percentageof Oil tank capacity, 5 gallons; rate of consumption. .20 pounds gross weight ,. Power plant 434 36.4 Ibs. per h.p. per hour. K,,, I ami oil 140 11.8 Pilot and miscellaneous equipment. ... 179 15.1 Summary of Performances Armament 98 9.4 (With I-e Hhone Kngine) llody structure 141 11.9 Height Speed Time of Rate of Climb Tail surfaces with bracing 36 3.1 (Keet) (m.p.h.) Climb Kt. per min. Wing structure 156 13.1 Ground 100-103 min. sec. 705 Chassis 74 6.9 5,000 8 min. see. 705 -..-."o 95 Total 1.188 100.0 118 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The VE-7 Training Biplane The VE-7 machine is designed around the 1 50 h.p. His- pano-Suiza 8-cylinder aeronautical motor, driving a direct connected two-bladed tractor air-screw. The entire power-plant unit, with all accessories, is mounted in a detachable forward section of the fuselage. General Dimensions Span, upper plmie 34 ft. 4 in. Span, lower plane 31 ft. 4 in. Chord, both planes S in. Gap between planes 4 ft. 8 in. Stagger 1 1 in. Overall length 24 ft. 5 in. Overall height 8 ft. 8 in. Areas (square feet) Main planes 297. Stabilizer 19. Fin 2.30 Ailerons 37.42 Elevators 17.09 Rudder 7.8 Main Planes Four aileron type, with cut-away top center section. The incidence is differential. No sweepback. Dihedral, 1^/4. Wings are in five units, assembled together with submerged hinges. In- ternal lateral control mechanism. Spars are of selected spruce, I-beam section, re-enforced at panel points. Ribs are of unit assembly type, built up of spruce and ash battens, with poplar webs, while for miscellaneous parts ash, birch and cedar are employed. The internal bracing system utilizes double swaged wires and forked ends attached to stamped mild steel fit- tings anchored to the main spars through neutral axles. Main plane fittings are submerged and the strut sockets are designed flush to the wing surfaces. Wing frames are covered with approved linen, or cotton fabric, specification sewed to ribs and " pinked " taped. Surface treatment is five coats of acetate dope and two coats of special grey enamel. Inter-plane struts are of selected spruce, solid one piece design, tapered slightly. The strut section is of very low head-resistance. Cellule bracing is Roebling 10-strand cable, fitted with Standard turnbuckles for adjusting means. Flying wires are doubled, landing wires single. Fuselage Carefully cleaned-up design of extreme simplicity. Fit- tings incorporate special anti-drift details. The frame is a box girder of steel and wood construction, unit type except for detachable engine mounting, with trussing of double swaged wires. Cross-section, rectangular but crowned top and bottom, tapering to a vertical knife edge at the rear. Dimensions at maximum section, 40 1 ';. in. deep x 30 in. wide. Motor housings and cowling are of stamped sheet aluminum, after portion being fabric covered. Cowlings enamelled light blue, fabric doped and grey enamel finished. Large, lunged vision doors render motor parts, control mechanisms and tail-skid system readily inspected and accessible. Seating Two seats, in very comfortable tandem arrangement, in well protected and upholstered cock-pits. Front seat be- tween wings, well forward to obtain vision. Cut outs in upper center section and lower wings facilitate vision from rear seat. Exceptional vision provided. Cock-pits fitted with re- enforced windshields. Longitudinal weights very close-coupled. Empennage Composed of fixed, double cambered st;ibilizer, con- nected dual elevator flaps, fixed vertical fin and balanced rudder. All frames are of steel, welded and brazed to- gether, wood rib filled, over tubular steel and spruce spars. System internally braced with swaged wires and car- ried externally by crossed cables and turnbuckles, giving a most rigid tail construction to withstand high stresses in " stunting." Empennage locked in place to fuselage by a series of exclusive design features. Tail units covered with wing fabric and finished to match. Doubled control wires connect up all control sur- faces. Chassis Type " V " strut and dual wheel design. Entire chassis quick detachable by removing 1 hinge pins. Wheels are 26 x 4 in., shod with Goodrich Cord Tires. Re-enforced stub axles of nickel steel operate in metal SI.\(;LK .MOTOKKD AKKOIM. \\ i - guide, with floating type shock-nbsorlH-rs assembled onto Illl-t.-ll spools. Axlrs. spreader tubes and sliock-ahsorhi r group well streamlined with stamped metal housings. " V " members of rll.-l-.--i-, are nf si leeti d brut ash. shock absorbers of ( ioodnch in. diameter clastic cord, cottiin sheathed. Wheels fitted with detachable st line fnlirir on ITS .-mil special oiling device. y IIII-III|MT in tin- complete chassis unit is pin con- . with adequate s.-it.t\ lurks, givinu -f at demount ability, desired llcxihility ;ind case of production, Met il parts finished in lilur enamel, baked on, while wood memhiTs .-in jjheii thn. oi.-its nt water-proof var- nish. Tail-Skid I itiiii: type skid, semi inmersal and si-lf-nlipiin^ in actic n. Is fitted with riil>ln-r cord sliork-alisorlier.s and ilile mi tal shoe. Assemlily ^rt-at-ablc through doors in ,idi of fnsclngf. All |iarts (|uick-detaehnble. Radiator Sp. .i,l hoiie\ eomli t\pe. located iii nose of fuselage, hoiisrd ill polished aluminum shell. Is eipiipped with dash hoard controlled slnitti r s\stem to reflate ciM>ling. Total water capacity in circulating system is ;pl , gallons, distance water thermometer installed. Oil radiator protruding Ix-low the under cowl is pro- vided in the oiling system. Including the capacity of the oil tank, the circulating s\ stem hold.s a total of five gal- lons of Inliricating oil. sufficient for over four hours wide i n tl\ ing. Fuel Tanks Two in numlier, main under rear seat, other in cowl M i n^iiie and dash-hoard, front cock-pit. Total fuel capacity is ;i I gallons, sufficient for over 2*4 hours at wide open throttle around sea-level. Carburetor supplied liy mechanical pump incorporated in motor. Hand air pump on dash for starting. Fin 1 shut otl' cocks in both cock-pits. Mufflen sheet steel tubular exhaust pipes extending along .sides of fusel ii;, back to rear cock pit. one on , a, b >,d. 1'ipis supported by forced SIM-| brackets. Control* Dual stick control of new d. SI U MI. comliined with stand- ard type adjustable fi>ot rudder bars. Control syst. semblcd as unit ami installed with k bolts only. Knginr throttle lever and altitude adjustment control pn.\ id. d in both cockpits. Starting magneto crank in rt-ar cock -pit only. All controls have thumb-screw tension locking de- rfaM. I. \.rs and parts nickel plated, polisl , ,| Starting Self-starting of engine obtaimd by special hand oper- ated .starter magneto. Rear dash cijuippcd with I.unken In iinir hand primer to motor to facilitate cold weather starting. Safety ignition switch visible to mechanic cranking also provided. Instruments and Equipment Altimeter, air sp< . -d indicator, \\althim clock, tacho- meter, gasoline and oil pressure gauges, primer. Boyce I.. 1). thermometer, fuel controls and Dixie switch, all arranged on unit dash-board. Equipment includes fire extinguishers, safety belts, small tools roll and miscellaneous small parts replacement kit. Engine Hispano-Suiza, 8 cyl., 130 h.p., water-cooled type, Model A. Propeller Liberty 2-bladcd, walnut, 8 ft. 4 in. diam. x 5 f t 5' - in. pitch. Factor of Safety A uniform factor of safety of U plus has been proved for the design by the latest French methods of sand load- ing. e Three-Motored White Monoplane Tin dimensions of the White lonoplnnes are: spread. 82 f eet ; length vcrall. 39 tot; height to top of weight empty. .S.7HO omul-. Total Inirscpowi r. 660. d by three Hispano-Sui/.a lues. Two I so H. P. engines are itnl .me on each wing on each side -dy. The third engine. .SOU 1 I' . ;s installed in the nose of the ^B as in single-motored aero- Tin- winas have a sweep- u-il tips and an angle of in of four degrees. 120 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The " Standard " Type E-4 Mail Plane, which has a capacity for carrying 180 pounds of mail. engine the machine makes a speed of 100 m.p.h. With an Hispano-Suiza 150 h.p, The Standard Model E-4 Mail Aeroplane Mail is now carried between New York and Washington in the specially built " E-4 " mail machine brought out by the Standard Aero Corporation. General Dimensions Span, upper plane 31 ft. 4% in. (Span, upper plane with overhang) 39 ft. 8% in. Span, lower plane 31 ft. 4% in. Chord, both planes 6 ft. in. Gap between planes 5 ft. 6 in. Stagger 5y 4 in. Length overall 26 ft. 1 in. Height overall 10 ft. lOy^ in. For winter flying, overhang extensions are attached to the ends of upper wings, increasing the span from 31 ft. 4% in. to 39 ft. 8% in. Areas Square Feet Upper plane 1T4.9 ( Upper plane with overhang) 230.3 Ailerons (2 upper and 2 lower) 48. Ailerons (with overhang) 56. Lower plane 162.1 (Total wing area, with overhang) 382.4 Stabilizer 23.7 Elevator 22.0 Fin 4.6 Rudder 10.1 Weights, General Pounds Machine empty 1,566 (Machine empty, with overhang) 1,616 Fuel and oil .". 390 Useful load 444 Total weight, loaded 2,400 (Total weight, loaded, with overhang) 2,450 Weight per h.p 14.1 Weieht per sq. ft 7.12 (With overhang; weight per h.p.) 14.4 (With overhang; weight per sq. ft.) 6.4 Summation of Weights Weight (Ihs.) Power Plant 778.5 Fuel and Oil 390. Pilot and miscellaneous equipment .... 364.3 Mail 180.0 Body Structure 288.1 Tail surfaces with bracing 75.5 Wing structure 324.0 Chassis 100.0 Percentage of Gross Weight 32.4 16.2 11.0 7.5 12.0 3.2 13.5 4.2 Total 2,400.0 100.0% WEIGHT SCHEDULE Power Plant Pounds Engine complete with carburetor and ignition system 455 Radiator 74.5 Water 75 Fuel and Oil Tanks empty 50 Propeller and Hubs 27.5 Cowling 61.5 Pipes, etc 35 Total 778.5 Fuel and Oil Fuel (60 gallons) 360 Oil (4 gallons) 30 Total 390 Pilot and Equipment Pilot and clothing 170 Dashboard Instrument ; 32.25 Miscellaneous 62 Total 264.3 Mail Mail 180 Total 180 SIXCJLK MOTOKK1) A KKO1M.AN KS Uody frame Body When overhang section is used, top of inclined struts irt i i uteri d I ft. s'_. in. from outer struts, leaving an o\erhang of -.'.'' -. in. vats ami Moor II. .1 Kront ami rear control .':'.7:, I''"' " Spad " truss is used between the planes, having a steel tul>e coinpression member l-t. en front and rear Total -'--.! middle struts. here Hying and landing cables cross. Tail Surfaces with Bracing Fuselage ili/.rr .4.0 '.lectors I ' The engine is carried on a pyramid type support. Mail is carried in a compartment situated at the center {udder 9.5 , . , . .... .?, of gravitv. |iist forward of the pilot s cockpit. I.I',, I it I II iu ^t w I ri , (it vi.tj \\hen the uiaeliine is at rest, the propeller axis is (5 ft. Total T.i.j in. above ground; in Hying position it is ."> ft. (I in. above Wine Structure ground. In Hying position, a line from wheel base to . . center of gravitv makes a 11" angle with a vertical line. I pper wmjr with lilting and ailerons 143.4 Lower wimritli lilting ami ailerons 129.4 A "- r1 ' between lin. joining wheel base and skid to a Interplane Struts and cables .1. liori/ontal line. II d< - minutes. Tlie stabilizer is fixed at a neutral angle. Total 3-M.il Chassi8 Landing Gear Wheels eo-nplete; Axle; Shock Alisorber, and I'nrts '> { Wli.-el Type l.andinir (Scar 93 The usual two-wheel landing gear is used, hut provision is made for the attachment of a third wheel, ax shown in the drawing, which adds 25 Ibs. to the weight. Performances Steel tube is used for chassis members, faired with Height Speed Timeof Climli Rate of Climb spruce streamline stiffening pieces. (ft.) (m.p.h.) (min.) (ft. per min.) 100 700 .WM) 10 Engine Group 10.000 ... 24 S, .,.wer Propeller t} |H- _> |, lnde Pni|'llrr diameter 7 fj ]<> j n I'roprllrr reinliitions |x-r ininutr I Chassis - Vee " -1 (tread 5 ft.) T ' ri " M in.x3 in. Area Control Surfaces Ail, n.ns: (four) 31.5 gq. ft. '''> ''"- 16* sq. ft. Kuddrr 8.5 sq. ft. I lori/nntal stabilizer 14.5 M|. ft. Vertical stabili/.rr 3.5 sq. ft. Stick tvpr control used. Performance High speed 105 miles per hour I .,m s|ieed 40 miles per hour Climb in first ten minutes 8000 ft. T} |n- I.I.VI pounds and is powered with an H<| horsr-pourr iles per hour and 1 1 feet in ID minutes. Thomas-Morse Type S-7 Side-by-Side Two-seater General Dimensions "> .'I ft. i, in. Spread 't ' ft Height 9 ft Weight and Lift Data Total weight loaded 1480 Mis. Area lifting surface (Including ailerons) 3ti M\. ft. Loading per square foot of lifting surface 4. Ibs. Kequiml horse power ..90 Wright of machine loaded |>er h.p 16J Ibs. Power Plant Ty|- of engine 80-h.p. I.e KhSne (air cooled rotary) Kngine revolutions |>er minute i .'.JD Fuel capacity, X) gallons, sufficient for 1' .. hours' flight at full power. Oil rapacity, gallons, sufficient for 3 hours' flight at full power. Propeller ty|>e .'-blade Proprllrr diameter 8 ft Pro|)eller revolutions p<-r minute Chassis Vee' view of the Thoma>-Mors< wing fitting at the left outer strut, Thomas-Morse Siile-liy-Side Tractor; an eye-bolt running through the turn- buckle plate attaches the strut fitting to the wing beam 124 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Thomas-Morse S-7 80 h.p. Le Rhone engine, side-by-side two-seater, designed particularly for pleasure flying. Wheels 2 (tread 5 ft.) Vertical stabilizer li.G sq. f.t Tires 26 in. x 3 in. Stick type control used. Area Control Surfaces Performance Ailerons: (four) 40 sq. ft. High speed 90 miles per hour Elevators 16.8 sq. ft. Low speed 40 miles per hour Rudder 8.5 sq. ft. Climb in first ten minutes 6TOO ft. Horizontal stabilizer 14.5 sq. ft. The Thomas-Morse Type M-B-3, 300 H.P. Hispano Engine Fighter -Streamline cap at wire crossing, middle interplane strut. 2 T.eft lower front strut socket. 3 Empennage, showing the un- usual arrangement of the elevator lever which is run on the inside of the vertical fin. 4 Operating arm on top of upper aileron. At the right is shown a sketch of the unique junction for attaching streamline wires to flexible aileron control cable. Thomas-Morse type MB-U single-seater fighter, equipped with 300 h.p. Hispano- Suiza engine. Span, 26 ft.; length over- all, 20 ft.; height, 9 ft. 1 in. Total weight loaded, 2050 pounds. Fuel and oil capacity for three hours' flight at full power. High speed 163 2/3 m.p.h., climb to 10,000 feet in 4 minutes 52 seconds. SIMil.K MOTOKKI) AEROPLAN] - < _ . .. *.v ~ " .A * "I- rv . Z..7T ^ ^iwl,!,!,.!,!^ ,li (irm-ral urrHiigi-iin-iit, and MMIW dt tails, of the Frrnrh A.H. biplane h /-/< C/./f . T^.. , *~+-*~t, -C-^J / O^mnjjor C- Ji^VWJ- FRENCH A .R. T yP /. Plan and elevation of the fuselage of the French A. R. biplane 126 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Four views of the French A.R. biplane The French A. R. Biplane This machine, designed by Commander Dorand, of the French Army, is designated as A. R. or A. L. D., according to whether it is fitted with a Renault or with a Lorraine- Dietrich engine. The machine is a two-strutter biplane of 13.30 m. span, and has its fuselage supported between the planes on ash struts. Sweep-back and dihedral angle are only present in the lower plane. The former amounts to 1 deg., while the dihedral angle is 2 deg. The top plane is staggered backwards 0.5 m. The gap is 1.825 and 2 m., respectively; that is to say, in the centre it is 0.945 of the chord. The angle of incidence of the upper plane is 2.5 deg., that of the lower plane 3 deg. The halves of the wings are screwed together in the centre of the machine. The wing spars appear to be of one section, covered on both sides with three-ply. Be- tween every two ribs, whose spacing is 300 to 340 mm., is a short false rib on the top surface only, running from the leading edge to the front spar. The wing fabric, which is of a cream color, is sewn to the ribs. In front of the trailing edge, which is formed by a wire, as in all French machines, eyelets are incorporated. The plane struts, which, with the exception of those secured to the body, are of hollow section, are of stream- line form. In order to prevent lateral bending the outer plane-struts are provided with a peculiar bracing. In addition the middle of the struts are braced to one another and to the bottom of the body struts. The strut fittings are of a very simple type, as shown in one of the illustra- tions. Strut sockets of sheet steel are secured to the spars bv U bolts, the two shanks of which pass through the spar and are secured by nuts on the other side. The flying wires and landing wires are anchored to the corners of these U bolts, while the incidence wires are secured to! lugs projecting from and forming part of the steel plate bottom of the strut sockets. This bottom is simply resting inside the socket and is not secured in any other way. SINCil.K MOTOKKI) A KHOl'LA.N KS r-'T The wing bracing consists of solid wires throughout, whifh arc corniced d to tin 1 fittings :iiul turnlmrklrs in the usual way by bending them OMT and sliding a ferrule of spiral wire OMT the free end. The Hying wires are in dii|ilie:ite and lie line In hind the other. The space be- tween them is tilled with a strip of wood. The external drift wire running to the nose of the Imdy is wrapped with thin cord to prevent it becoming entangled in the propeller in ease of breakage. Hctuccn the fuselage and the lower plane there is diagonal bracing in the plane of eaeh spar. As. howe\er. there is no corresponding bracing aho\e the fuselage, the upper ends of the top plane body struts are allow eil a eoiisideralile amount of play. \on hal meed ailerons. positively operated, are hinged direet to the rear spar of the top plane only. The aileron eontrol cables are in the form of simple cables running from the sprocket wheel on the control column, around pulleys in the lower plain-, along the lower side of the lower plane and under another pair of pulli \ s. From this point on tin \ are in the form of solid wires of 2 mm. diameter riinnini; to the aileron crank lexers, which are in the form of quadrants. The upper cranks of the ailerons are connected by cables and wires running across from side to side, along the upper surface of the top plane. At tin- stern of the fuselage is fixed a small tail plane to which is pivoted the balanced trapezoidal elevator. The rudder is also balanced. The rudder post is braced to the cletator. and this in turn to the body, by stream-line steel tube struts. The ends of these struts are flattened out and bolted to the various fittings. There is no vertical fin. The rudder is controlled by plain wires of 2.5 mm. diam- eter. Only where they pass over pulleys have cables been substituted for the wires. The undercarriage struts are secured to the spars of the lower plane at the points where occur the attachments for the struts running to the body. The short body struts are braced by stream-line tubes fore and aft to the body. The one-piece axle rests between two cross struts of steel tube. The travel of the axle is not restricted. The undercar- riage is braced diagonally in the plane of both pairs of struts. Tin- longerons and struts of the fuselage, which is fabric covered, are made of ash up to the observer's seat. From there they are made of spruce. The struts of the rear portion of the fuselage rest on the longerons without any attachment, and are held in place by the bracing only. To prevent them from sliding along the longerons the ends of the struts are notched to correspond with the shape of the wiring lugs, which surround the longerons. The 8-cylinder, Vee type Renault motor develops, ac- cording to a plate in the pilot's cockpit, 190 h.p. at 1550 to 1 tii MI r.p.m. The radiator is placed between the body and the lower plane. Then is a shutter arrangement for varying the cooling. A water collector or (.ink is placed above. the port row of cylinders. The exhaust gases are carried outwards to cadi side through short collectors. \\'ith the older motors the exhaust from both row of cylinders was carried inwards to a common collector car- rying it up above the top plane, an arrangement which greatly hampered the \ n w of the pilot. In these machines the radiator was in the nose of the body. An auxiliary radiator was placed In-low the fuselage. The motor is bolted to two channel section steel bearers, which rest on strong sheet st, , I cr idles. Imm.diit. Iv be- hind the engine is placed transversely the oil tank, which has a capacity of 7 litres. Tin- main petrol tank, which has a capacity of I7< litres, is divided into three com- partments, and :> placed behind the pilot's seat. From here the petrol is pumped into a small gravity tank holding 1-' litres and placed behind the engine. For this is em- ployed either a pump driven by the engine or a hand pump to tlw right of the pilot. If too much petrol is pumped through it is returned to the main tank via an overflow. The pilot sits in a line with the leading edge of the top plane. Here he has a very good view forward, but the view in a rearward and upward direction is very restricted. On the instrument board in front of the pilot are the following instruments: A cooling water thermometer, ignition control, compass, petrol cock and revolutions in- dicator. To the right, at the side of the scat, is the petrol hand pump elevator. On the left are the levers for advancing or retarding the ignition, the petrol and air levers, the radiator shutter control, and the oil cock. In the floor of the fuselage, in front of the rudder bar, there are small windows. In the observer's cockpit there are two folding seats, one in front and one at the rear. In front, behind the petrol tank, there are on each side racks for four bombs. Between these racks, through an opening in the floor, the photographic camera can be inserted. A shelf for plate holders is placed behind the port bomb racks. On the starboard inner wall of the observer's scat are aluminum plates for the switches and keys of the wireless. The other instruments of the wireless are placed aft of the seat. The pilot is armed with a fixed machine gun placed on the right-hand side above the body, and is operated from the left cam shaft. Firing is accomplished by Bowden control from the control wheel. The observer has two movable machine-guns, coupled together and mounted on a gun ring with elevating arrangements. 128 TEXTBOOK OF APPLIED AKKOXAUTTC ENGINEERING A French Breguet bombing machine in flight. On the rear can be seen twin Lewis guns mounted for use of the aerial photog- rapher or observer The Breguet Biplane This biplane, characterized by two sets of struts, is pro- duced almost exclusively of aluminum, and is intended for bombing purposes. The upper planes have a backwards stagger of 0.21 m. and a span of 1-1.4 m., and are mounted on a cabane frame, while the lower planes have a span of 13.77 m. Both upper and lower planes have large cuttings at the fuselage and their arrow shape amounts to 175 deg. The angle of incidence of the upper planes is 4.5 deg. in the middle and 2.5 deg. at the ends, that of the lower ones decreasing from 3 deg. to 2 deg. The spars of both planes are drawn aluminum tubes of rectangular section 65.6 x 31.6 mm. The thickness of the walls of these tubes amounts in the inner section of the upper plane to 2.6 mm., elsewhere to 1.6 mm. The rear spar grows thinner towards the wing tips till the thickness of the edge, where auxiliary spars with ash bands of 6 mm. thickness and 3 mm. three plywood glued to both sides are provided. At the points of juncture and at the ends of the stampings the spars are strengthened by ash pieces, in some instances of I shape. A socket of 20 cm. length, made of welded sheet steel of a thickness of 1.5 mm., is provided at the strut ends of the upper planes and at the strut bases. These sockets and the wooden linings are held in position by iron tube-rivets. The main spar of the upper plane is strengthened in the interior section of a pine support of a thickness of 10 mm. being fixed to one side of the spar by means of small brass screws. The spars of the upper planes are equipped with compression supports at the joints of the two sets of struts and the lower planes for the outer strut set, the support being an aluminum tube of the diameters 30 and 27 mm. exterior and interior. Further there are two aluminum ribs of a width of 40 mm., one at the beginning of the ailerons and one by the bomb store in the lower plane. The interior wiring consists of single wire. The ribs are very strong. They have a depth of 2 mm. above, of 1.9 below. A web provided with weight dimin- ishing holes is glued between the longitudinals of three- ply wood, 3 mm. thick. On both sides of the spars as well as at five points between them the flange is strengthened by glued and nailed birch laths and wrapped bands. The ribs are arranged loosely on the spars. The ribs lie par- allel to the axis of longitude, forming in relation to the spars an angle corresponding with the arrow shape. They are connected with each other by means of the veneer planking, reaching on the upper side from the leading edge to the main spar, as well as by the leading and trail- ing edges. Further they are connected by two bands, lying behind each other and alternately wound from above and below the ribs. The distance between them amounts to 40 mm. Forward and in front of the rear spar more 1 mm. thick auxiliary ribs of plywood are arranged. To reinforce the aerofoil, thin birch ribs reaching to the trail- ing edge are screwed to the rear of the ribs on the under- side. The yellow-white colored fabric is sewed to the ribs and secured with thin nailed strips where exposed to the air-screw draught. The provisions of hooks and eyes on the under side of the planes behind the leading edge and in front of the trailing edge is to permit the draining off of moisture. The part of the lower plane lying behind the rear spar is hinged along its total length and is pulled downwards by SIMil.K MOTOKK1) AKKOl'l.AM.s in' in-, of I -J nil. In r cords fi\.d on tin- under s.de ..I the ribs, tlu- tension of these r.-m IM adjusted In means >< scr.ws. .in :iiitoin;itic cli.in^i ot tin- :iiTiify means of liolts passim; riijlit through. Tin spars hail- no linings at thesr po.nls. The coiistrm (ion of tin stampings nf the spars is \ kg. |>er s(|. Him. with a stretching of 18 per rent. The l ndinj: figure is I 2. The I-..! nun. thick load-carrying cables are double, the spaee lietwicn tin in being tillet-ttcr support to the lower planes, beinir much stressed by the |MIIII|I .store, the load- carrying cables are in the inner section led to the stamp- ing on tin main ribs arranged by the ttomb store, ami them, downwards to the landing gear. The rear spar of the upper plains is also provided with a cable to the fuselage between the c.ibane and .strut. Tin- stampings for the fixing of the wiring is constructed \.-ry simply. A bent sheet metal of L' form and with drilled holes for the bolts carries the nipples of the eye- bolts. The Fuselage The canvas-covered body consists almost exclusively of aluminum tubes that are riveted with welded steel tube si. .MX : i|.l spanned with wire. Onh .it >p. i-ially stressed points in the front part li.-uc steel tnU-s In i n einployi-d. Tin up|K-r and lower sides of the 1 i . inded b\ the eiii|ilo\ment of fairings. The . iimn. r. s|> on aliiminiim I In -an rs that art- sup ported ly ri\eteil aluminum struts. Two pairs of large \iew trips an prox ided U-low the seats of tin- pilot and olisericr. and are operated by cable by tin obs. rvi r. The Undercarriage The \cr\ stroiij; landing gear has three pairs of struts of aluminum streamline tubes, strengthened \>\ 1 irons riveted in. and resting In low on hori/.ontal steel tubes. Tin- wheel shaft rests in an auxiliary one of steel sheet in t shape welded on. The back root points of the strt:ts are connected by means of a second steel tube auxiliary .shaft, welded on, and liy a tension hand lying behind. A diagonal wiring is further provided hori/.ontally in tin auxiliary shaft level. The streamlining of the shafts is cut out in the middle behind the front auxiliary shaft to improve tin sight downwards. There is only a diagonal wiring to the fuselage in tin level of the miilill. struts. The ash tail skid hangs in rubber springs from the fuselage and is strengthened in the rear end by a con-r ing of a rectangular aluminum tube. Its wire stay is sup ported ill the rear stem by a spiral spring. Leaf springs are further fixed to the end of the skid. Tail plane, rudder and elevator are of welded thin steel tubes. The aeroplane is equipped with complete dual control. The control in the observer's cockpit can IM- removed. The ailerons are interconnected. The twin control <'alil.s run behind the rear spar of the lower planes to two direction changing rollers resting on a shaft. Here they part and are led as separate wires of thickness of 2 mm. to the underside of the aileron. In the upper plain s the ailerons are connected by control cables, governing two levers ill each side. The ailerons are balanced and welded to a common shaft. ' A squadron of l-'rcndi Hrejruet bombing machines 130 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING LIFt BOAT FORMING FAIRING OF FUSELACE. WHICH CAN ' tO. INSTANTLY, RELEASED FROM. -. PILOTS SEAT COCKPIT FOR PILOT AND NAVIGATOR 375 HP ROLLS ROYCt "EAGLE." ENGINE PETROL TANK CAPACITY ABOUT 400 GALLONS FOR 25 HOURS FLIGHT ENGINE EXHAUST PIPE TO ELIMINATE RISK OF FIRE The Sopwith biplane, in which Harry Hawker attempted to fly across the Atlantic The Sopwith Machine The Rolls-Royce engined Sopwith transport type spe- cially designed for crossing the Atlantic, is of the vertical Scale plans of the Short and Sopwith transatlantic type aeroplanes liplane type, the wings having no stagger. Pilot and navigator are seated well aft, so as to give a large space in the fuselage between them and the engine, in which to fit the large petrol tank required for the great amount of fuel that has to be carried for a flight of this duration. The cockpit of the occupants is ar- ranged in a somewhat unusual way, the two seats being side by side, but somewhat staggered in relation to one another. The object of this seating arrangement is to enable them to communicate with one another more readily and to facilitate " changing watches " during the long journey. The very deep turtle back of the fu- selage is made in part detachable, the portion which is strapped on being built so as to form a small lifeboat in case of a forced descent at sea. The Short Machine Fundamentally the Short machine entered for the race does not differ greatly from their standard torpedo carrier known as the " Shirl." It is a land machine fitted with wheels. In the place between the chassis struts usually occupied by the tor- pedo in the standard " Shirl " is slung a large cylindrical fuel tank which, should the necessity arise, can be quickly emptied so as to form a float of sufficient buoyancy to keep the machine afloat for a considerable period. In order to be able to carry the extra weight of fuel neces- sary for the long journey larger wings have been fitted, having three pairs of struts on each side instead of the two pairs fitted on the standard machine. SIX<;i.K MOTOKKI) AKKOIM.ANKS 131 The transatlantic flight type Martlnsyde hiplane at ! The Martinsyde Type Tin- machine is more or less of standard Martinsyde type, with tlir occupants placed very far aft to allow of mounting a large fuel tank in the middle of the fuselage, in the neighborhood of the center of gravity where the decrease in fuel weight as the fuel is used up will not alter the trim of the machine. In outward appearance it does not present any radical departure from the standard. It had the distinction of being the lowest powered machine in the race, the engine being a Rolls- Royce " Falcon " of 2H/i h.p. The general specifications of the Martinsydc are as fol- lows : Spun. l>th planes *3 ft. 4 In. Chord. Inith planes 6 ft. 6 in. Gap lietween plnnos 5 ft. 6 In. Area of main planes MM) &q. ft. Overall length -'7 ft. 5 in. Overall heiffht 10 ft. lo in. Fuel capacity 373 gallons Cruisinir radius ->.ooo miles Speed 100 to 1 m.p.h. Captain Frederick Philips Raynham, the pilot of the Martinsyde aeroplane, went with the Martinsydes in early development days in l'.K)7 and was with them when they began monoplane production in 1008. When the war began Martinsydes turned to building biplanes and the present machine is but slightly modified from their latest fighter. The machine for the transatlantic flight was taken from stock and still carries its original equipment such as used during the war. The Martinsyde "Hayntor' 132 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING FRONT ELEVATION. SIDE- ELEVAT.ON. Line drawings of the Grahaine-White Aero Limousine equipped with two 210 h.p. Uolls-Hoyce motors and tractor propellers. Grahame- White Aero Limousine The machine accommodates four passengers and a pilot, the latter in a separate compartment behind the pas- sengers, who have a perfectly clear view forward, down- ward and sideways. The limousine body is as luxuriously equipped as a modern interior-drive motor-car, and is equally commodious. Unsplinterable glass windows, both wind and draught proof, are fitted, and it will no longer be necessary, when using such a machine, to clothe one- self specially for flying. The limousine has a heating ap- paratus, a ventilating system, and a speaking tube connects it with the pilot's compartment. A specially-designed system of maps, under the control of the pilot, indicates to the passengers at a glance, and at any time, their exact position during a cross-country flight. The raised posi- tion of the pilot ensures him a clear outlook, and he is ideally situated for controlling both the machine and mo- tors. The two 270 horse-power Rolls-Royce motors are si- lenced as effectually as is the engine of a car. The use of two motors, either of which is sufficient when running alone to maintain the machine in flight, eliminates almost entirely the risk of a forced landing. The machine has a speed of 105 miles an hour, and will fly in anything up to a 4.0-miles-an-hour wind in perfect safety, and without discomfort to the passengers. With the motors throttled down, an easy touring speed of 60 miles an hour can be maintained. The four-wheeled chassis, designed on mo- tor-car lines, gives a maximum of strength and efficiency, and is fitted with special brakes which bring the machine quickly to a standstill on landing. It will also rise from the ground after only a very short run. The wings fold back, as shown below, to reduce housing space. With wings folded the span is reduced from 60 feet to 29 feet. The Farman " Aerobus " being used in the Paris-London passenger service. Two Salmson engines are used. Note the wing end ailerons. SINCJl.K MOTOHKl) A KK( )!'!.. \.\KS The German Gothas, the Aviatiks and the Ago biplanes Goths G2 THE H. and M FAR.MAN FIGHTING AEROPLANE 134 SI.NU1.K MOTOHKI) AKKOl'I.AM ^ Ii I I Scale drawing, with dimension', in niilimrtrr., of the Type 17 Nii-nport M-out The Nieuport 1% Plane* An immediate step in the transformation from the mono- Jam- to the biplane is formed by the biplane with a larger op plane and a smaller bottom plane. This type, pro- Itici-il liy tin N import firm has speed and ease of handling. I'hii-li is characteristie of the monoplane, and stability and liort wing span, which is found in biplanes. Tin- N imports may be divided into three main types Pyp<- 11, a single-seater with rectangular body up to the nginc cowl, and the eowl covering the upper end of the notnr only; Tyjie 12, which is a two-seater, having its V nti rplane struts sloping outward, toward the top. !n this type tin- top plane has a fixed center section and i.s vercd with transparent Ccllon sheets to give a better The power is provided by a 110 h.p. Clerget en- tin. . The observer sits behind the pilot. The Type 17, of which we give here a line drawing, is a single-seater, with a circular front section, and some of this tyjie have a spinner over the propeller boss. The general arrange- ment resembles that of the Type 11. The ailerons are mounted on steel tubes, inside the ring and running along the back of the rear spar to the body. These tubes are operated from the control lever by means of cranks, pull-and-push rods and a crank lever. The (ranks are hollowed out to provide clearance for the rear spar. The top plane has slots cut in it for the cranks. The pull rods are connected to the crank lever by ball joints. The hand lever and the rudder pedal are the kind usually used. The top of the rear portion of the body is covered with curved veneer. The tail skid is supported on a structure 136 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Xieuport scout aeroplane flown by American airmen in France. It measures only 15 meters from tip to tip, and is driven by a Hit) horse-power Gnome motor and a French propeller of veneer projecting down from the framework of the body. The machine-gun is rigidly mounted over the center of the body, directly in front of the pilot. Herewith are the dimensions and weights of one of the Nieuports: The Type n Single Sealer Span, upper plane 24 ft. 8 in. Span, lower plane 24 ft. 3 in. Chord, upper plane 3 ft. 11 in. Chord, lower plane 2 ft. 5 in. Overall length 18 ft. 10 in. Height 8 ft. 1 in. Area, upper plane with ailerons 97 sq. ft. Area, lower plane 49.5 sq.ft. Area, rudder ; 6 sq.ft. Area, ailerons 14 sq. ft. Area, stabilizer 11 sq. ft. Area, elevators 14.5 sq. ft. Stagger 2 ft. 3 in. Dihedral, upper 179 Dihedral, lower 174 Sweepback 170 degrees 30 min. Incidence, upper 1 degree 30 min. Incidence, lower 3 Power plant 80 h.p. Le Khone Propeller, diameter 8 ft. 2 in. List of Weights Upper plane with fittings 79 Ibs. Lower plane with fittings 33 Ibs. Tail plane 7.7 Ibs. Elevators 9.5 Ibs. Rudder 6.6 Ibs. Body with engine, complete 583 Ibs. Wire stays '. 7.7 Ibs. Wheels 22.4 Ibs. Interplane struts 11 Ibs. Gross weight, empty 760 Ibs. Pilot 176 Ibs. Gasoline (20y, gallons) 121 Ibs. Oil (5 gallons") ..'. 44 Ibs. Machine gun and ammunition 110 Ibs. Useful load 451 Ibs. Total weight, loaded 1,210 Ibs. The climb in 4 minutes is 3300 ft. ; 7 min., 6600 f t. ; 11 min., 9900 ft; 16 min., 13,200 feet. The lift loading o the machine per sq. ft. equals 8.3 Ibs., and the power load ing, 12.1 Ibs. per h.p. The propeller is a Levasseur, of 2500 mm. diameter an< a blade width of 270 mm. Comparative table of the three above mentioned types Xo. 11 Xo. 12 Xo. 17 Le Rhone, 80 Clerget, 110 Le Rhone, 11 7,520mm. 9,200 mm. 7,400 7,460 1,200 1,820 700 900 13.65 sq. m. 22.2 sq. m. Motor Top Span Bottom Span Top Chord Bottom Chord Total Area Incidence, Top 8,300 mm. 7,800 1,230 730 15.6 sq. m. 1 deg. 40 min. 2 deg. 30 min. 2 deg. 30 mir Incidence, Bottom 3 degrees 3 deg. 30 min. 2 degrees View of the forward end of a Xieuport, showing the cowlin| completely surrounding the motor, which distinguishes thi Type 17 Sl.\(;i.K MOTOHKl) AKHOl'I.ANKS i:J7 ii|>orl Scout itli twin l.rwis guns ami lixnl \'ickrrs gun A I'M-. I r, i,rl, Xiruport S.-..iil in flight. \ import Hipl.-me rqtiipprd with a ( 'Irrupt motor Testing out a 120 h.p. I.T Rhdnr motor on I '. meter Nieuport ty|- J~.\ 138 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Side view of the Salmson biplane, equipped with the Salinson motor A French Salmson biplane. Two seated, it is used for artillery observation and contact patrol A Salmson biplane with a 250 h.p. Salmson stationary radial motor SI.M.I.K MOTOR Kl) A KRO1M.A M .S l.T.i III. I 'rent h Spml liiplunr i-<|iii|>|>cd with Ilispiino-Snizii motor The Spad Scout, Type S VII is type of plane has been used by many of the best Allied a\ i itors. .\pprii\iiii.-iti- general dimensions of the S VII are as follow - Span, uppi-r pliine (7.800 metres) J.> ft. (i in. Span, lowt-r plane .'."> ft. li in. Chord. Inith plane. (1.4IHI metres) 4 ft. 7 in. ll.-ip Ix-twn-n planes ( l.-'.'.'i meters) 4 ft. -' in. llvrrnll length (li.KHi meters) 90 ft. in. T( n I weight ... I/)- 1 .'. Mis. I...-K! 47(1 lli>. I Mini, in 10 minutes 9,100 ft. Sperd nt sea level lit.' m.p.li. t :(.("> n*T>rs I .'h m.p.li. fltta V tjpe Ilio h.p. Both pl.-itn s are nearly rectangular in plan, the i-nds U in;; si|ii in .-mil not rnkcd, with eorncrs slightly rounded off. Tin deep eut-out portion of the top plane, over the pilot's seat, as well as the elose spaeing of the intcrplane struts, shows a large area of plane surface aft of rear wiii In .mis. As the ailerons arc comparatively narrow, nist IK' carried on a subsidiary wing spar located about 9 inches back of the main beam. It will In- iidtii-rii that tin- iiiti-rpl.-iin- bracing is iiiiiisu.-il : 's from each side of the fuselage extend directly to i struts, crossing at the intermediate struts. Where rea i ross tin-re is a steel tube brace connecting the .1 with rear intermediate wing struts. The fuselage is exceptionally deep, and the bottom is curved In-low the lower longerons as well ax the sides and top, giving a smooth streamline effect. The fore end of the machine, which house* the motor, is covered with aluminum, with a circular radiator opening which n -. m blcs the cowling of a n>t.-iry motor. I'rotulioranccs on cither side of the cowl show where the camshaft covers of the Hisp.-ino Sui/.-i motor project. Perforations are made in the cowling, about the motor projections, for the admission of air. The rudder is hinged at a point about 1<> inches Ix-yonil the fuselage termination. The usual fixed sUibilixing plane and elevators are employed. The vertical fin ex- tends 12 inches forward of the leading edge of the tail plane. Wheels of the landing gear have a track of 5 feet; the axle runs in slots which guide it up and backward in line with the rear chassis struts. Shock absorption is with rubber cord. The Hispano-Suiza motor develops 1GO h.p. at about 1500 r p.m. Eight cylinders arranged V type, water- cooled, four-cycle, 4.7245-inch bore by 5.1182-inch stroke; piston displacement, 718 cu. in. Wright, including car- buretor, magnetos, starting magneto, crank and propeller hub, but without radiator, water or oil and without ex- haust pipes. 4-15 Ibs. Fuel consumption, one-half pounds of gas per horsepower hour; oil consumption three quarts an hour. 140 TEXTBOOK OF APPLIED AEK' \V \ '1C ENGINEERING A French Spacl biplane. It is a single seater and Was used for pursuit work. It is equipped with two syn- chronized machine guns and is driven by a Hispano-Suiza motor of 320 h.p. Rear view of the 220 h.p. Hispano-Suiza Spad biplane A front view of the Spad biplane. Note the metal interplane struts, the " Eclair " propeller, and open cowl. SIM I W>KK1> .\KUUIM..\\KS I n Front \irw of (hi- Sp.ul I .111011 SIMJ, .s.-.ilrr. Knprir: .'.'n lip. 1 1 i-p.-uui Sni/.i. It li . n :t7 mm. (1 inch) cannon khootiiifr through UK- hull ul tin |irii| Hi i. .uul ..!-.. tun lixnl >\ uchronixeU gun* Siilr u Spud Cniniii Siiifrlr Sealer. ^.'0 h.p. Ilispnno-Suizn engini-. '|'|M- motor N completely eiu-knrd in the cowling. Tin- excellent >treainlinc shape of the fuselage can be seen from the photograph Spud 11-A3 Two Seater. Kn(rine: r h.p. I li-pmio -SuUa. I'M-I! t.ir ul -rvalinn pur|xM^. S|eed at 6i(K leet: II.' luili--- per hour. Climh to |li,VK( feet In :.' tniiiute'i. r'mliirnnce at gronn.l l.-v.-l: J hr-. l.i inin. Arm.imrnt: one stationary (fun ami -' flexihle gunv Crew: one pilot and one oliM-n.-r. l-'ipiipiiH-nt: Radio iind camera SKETCH OF BRISTOL SCOUT WITH Ls RHONE ENGINE J mm < CO ? Q i < CL uj 142 SINCil.K MOTOKKM A I .!{< )IM.A\ KS WITH LeRHQME C NO INC Bristol Scout 80 Le Rhone Tin- Bristol Scout was adopted by the United States Army for .idv.inrrd training in 1918-19. ti of tli<- Bristol Sc-out at Wilbur Wright Field gave th. follow in_- results: .-d (ft.) M.p.h. R.p.m. i, ., , I.... - MM -'. M15 Cli.nl. (ft.) 10,000 75 Time 1 1 ruin. 45 rc. .M miii. .' nee. 1.170 Ratr (ft.) tin 240 Srnirr orllln^ (climb 100 ft. per m!n.) 13.000 ft. Wright, rtnpty 7f MM. Total ICMI! 2M BM. Bri-tol Scout with 80 Lr Bristol Scout with M \JT Kh6nr 144 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING TOP VIEW U5B-1 FIGHTER WITH 3OO H.P HISPANO - SUIZA ENGINE U. S. B.-l British Fighter 300 Hispano-Suiza U. S. Army Tests Summary of Results U. S. B-i Useful load 724 Ibs Fuel and oil . . 344 Ibs. Total weight 3,910 Ibs. Pounds per sq. ft.' . . 7 05 Pounds per h.p 9 7 Gasoline consumption Oil consumption g . ," ,llSJ Climb (ft.) Time R.p.m. Speed H.p.m. 114.5 1,760 6,000 5 min. 35 sec. 1,600 113.fi 1,700 10,000 10 min. 45 sec. 1,600 109.5 1,660 15,000 19 min. 30 sec. 1,600 101 1,600 Theoretical ceiling: . . 25.000 ft. ' U. S. B-l with 300 Hispano-Si iza SINCil.K MOTOKKI) A KKO1M.A M .S FRONT VIEW USB-I FIGHTER WITH 3OO HP HISPANO- 5UIZA ENGINE I S ll-l with :>0 Mi-|).n;i>-Si i Marlin-yilc Scout with :KI IlispiiiiD-Siiir. i llrixt.,1 Smut with -i) l.i- Hhoni- ISrisl.il So.ut with 146 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING FRONT VIEW U.5.B-B FISHIER WITH E9D H.R LIBERTY ENGINE U. S. 15-.' with I.ilicrtv "8' U. S. H--' with Liberty "S" crz U. S. B-2 with Liberty "8" S. B-2 with I.ihi-rtv SIXiJI.K MOIOHKI) .\KK01M. \\ I ^ 147 Martln&yde Smut \vit M.irt. ml with :VM> 1 Iis|>;iiici-Sui Martinsyde Scout 300 Hispano-Suiza Summary of Trials (British) Duty - - Fighting. Knginr Ilispano-Sui/a. .SO/i h.p., at 1800 r.p.m. I'n.p.-llrr- I). K. (i.l.. .V.J70. Din.. -'7 IO. Pitch, 2080 (marked i. DI.I., U Military load 281 11>- Total Wright, fully Inadril 2289 Ibs. Ui -ight |IT s at this height 1 10 ft. mill. Air i-inliir inr. . almut 2'/4 ''rs. at full speed at 15,000 ft., iiu-luiliiiir climb to this height. Anrroid II.,,. I, I Radiator Temperature Readings on Climb Atmox. K nl Temp. C. Temp. C.' AoiX Miu. Sec. Climb to 10,000 ft.. 6 40 Climb to 15,000 ft.. II 45 Climb to ->0,(K)0 ft.. 19 40 R.ofC. in ft. mill. 1,176 850 R.p.m. I.-." 1,795 5,000 IOJOOO IQflOO li 7 _fl 18 -s n ra 7:f 77 74 Pos. of K.p.m. HlimU l.i,.l" Oprn UlM 0|irn 1,610 lip, i, l.vi-, i |.... .1 1^75 I.8.S. 70 65 60 H.p.m. 1,610 I. vi-, 1,570 SiT\icr ri-ilinjr (height at which rate of climb is 100 ft. min.) a-l.-SOO ft. Kstimatcd absolute ceiling 26,800 ft. Oil Temperature Readings on Climb Starting with nil tank full. Castor oil, 4 gallons. Aneroid \tmnv Oil Kiipine Oil I'n-Mirr llriftht Temp.C." Temp. C." Trmp. C. lb./q. ft. (J.iMHt 6 60 74 75 10,000 " 75 78 70 H.OOO 7 85 80 65 16,000 9 90 80 60 TOP VIEW U.5. B-S FIGHTER WITH B9D RR LIBERTY ENGINE 148 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING SEA 402. Engine: Lorraine 390 h.p. Two Seater Pursuit Biplane. Speed at 6500 ft.: 129 miles per hour. Climb to 17,000 ft. in 21 min. Crew and armament: Pilot has two fixed guns. Gunner has two flexible guns. Endurance at ground consump- tion: 2 hrs. 30 min. Hunriot Dupont HD 3-C2. Engine: Salmson 270 h.p. Two Seater Pursuit Biplane. Speed at 6500 ft: 128 miles per hour. Climb to 16,500 ft. in 25 min. Crew and armament: One pilot with two fixed guns. One gunner with twin flexible guns. Endurance at ground consumption: 2% hours. Side view of the Hanriot Dupont HD 3-C2 with Salmson 270 h.p. motor Side view of the SKA 403 with Lorraine 390 h.p. motor tl * > -i ? X / u X ,1 150 SIN(;i.K MOTORK1) A KKOl'l ..\ \KS 151 1**" \nirricjin S. K. ."> with 1 s * > I li-jniici Sui/a The English S. E. 5 Single-Seater Fighter This biplane li.-is i surface of 't.H si|iinrc metres, and both |il:iiii-s. connected with hut our pair of struts to each .sidr. II.-IM- a span of K.l.'i metres, and a chord of 1.5*2 metres, the gap I'niin tin' top of the fuselage amounting to 41. ' :. mrtrr. rrow shape prevails. Tin- V shape* of tin* rqual- .si/.rd rnds of the upper and lower planes mounted on the centre section and respective body rudiments amounts to 1.7 I tlejirei |, The siirlit field is improved hy cutting the centre section in the middle and the lower planes near the body. .\lio\e the aniile of incidence is 5 deg. mean, below by the hod\ li dt ir., by the struts 3 deg. Both plnnc .spars show sections of I shape, wl the longerons are steel tuln-s of 1.7.5 millimetre thicki and 1.5 mm. outer diameter. There are no compression struts between the spars. MMMI of the ril;s being solid struts instead. The interior wiring of the planes between the body and the struts is carried out in simple profile wire, that of the overhanging ends of thick -ended wire. 5--5 PLANE WITH HISPANO-SUIZA ENGINE 152 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING TOP 1//EW S-E-5 PLANE WITH H/SPANO-SU/ZA ENG/NE A wood strip forms the back edge of the planes. Fur- ther, two auxiliary ribs ranging from the leading nose edge to the main spar are arranged between each two ribs. The fabric is sewed together with the ribs, and is painted yellow below, browned above, as is the fabric of the body. Shoe-eyes are arranged on the underside of the trailing edge of the plane to assess the pressure. The centre section struts are covered steel tubes. The plane spruce struts rest in long stampings, serving as fix- ing points of the vertical wiring. Profile wire is employed for the plane cross wiring with twin wires for those carrying load and single for the counter ones. The two spars of the upper planes are strengthened further between the centre section and the struts with two wires each. Unbalanced ailerons are hinged to the back crossbar of the upper and lower planes. The body shows the usual strut and wire combination, being rounded above with half-circle frames and fairings, and having three-ply wood planking of 4 millimetre thick- ness to the pilot's seat. Fuselage longitudinals and struts have sections of I-shape, except the vertical struts behind the pilot's seat, which are worked out round. The tail-plane is curved to both sides and fixed to the body, so that the angle of incidence can be varied during the flight within the limits + 4.5 deg. and 3 deg. To this end the front spar is turnable, while the rear spar, with its wiring, is fixed to a tube, arranged shiftable to the body stern post. This tube rests with a piece of thread in a gear-nut, again resting in the stern-post fixed, yet turnable. When the nut is turned from the pilot's seat by means of wheel and cable, the tube is displaced upwards or downwards, transferring thereby the same manoeuvre on the rear spar of the tail-plane, and thus its angle of inci- dence changes. The elevator hooked to the fixed tail-plane partakes in this movement. The wires for operating the elevator are led through the body and tail-plane, which certainly saves air resistance, yet makes twice a 20 deg. direction change of each wire necessary. Main and tail-planes are equipped with cellon windows, rendering a control of the rollers possible. The under-carriage shows the normal form. The through-running axle rests between two auxiliary ones, There is no limit of the springing range. The tail skid shows an unusual construction, being ar- ranged turnable behind the stern post and connected with the rudder cable by intermediance of springs. A brass skid bow is sprung by means of two spiral pressure springs which are prevented from sideway turning by inserted telescope tubes. According to the firm's sign board the Wolseley-His- pano-Suiza engine gave the 30th August, 1917, on brake SINCil.K MOTOKKl) A I .!{( MM \ \ 1 - 1 :,: .mi h.p. -.MLS I'.S. .it -.MIII.-, revolutions. Tin- r.p.iu. of tin- fi>nr hladi d airscrew is i;eirid down in tin- ratio ot I- to .'I. 'I'lir exhaust gas is li-cl behind tin- pilot's seat in two tulics to i-.-icli siilr ot tin- hodv . Tin- motor sits so that thi-rr is (fit :i,-( -i ssilulity al'ti-r removing tin li. ct. The r/iili itor forms tin bow of tin- I odv . A i-oM-r amm-emi-nt makes it possible t<> uncover the body alioiit halt way from tin pilot s - Tin- main prtrol tank of IJH litre-.' capacity is | lu-hiiul tin motor on the upprr tusi-laii 1 ' longitudinals. A gravity tank of 17 litres capacity is arranged in the centre section between the li ailiim nl-t .mil the main spnr. Tin- oil tank of a capacity of I 1 litres lies cross in the engine frame below the nar eil^e ot tin motor. The fuel sullices Idr a (light of about two hours' dura- tion. Following instruments are -irmi^d in the pilot's seat: To right: A ho\ for the light pistols; a contact breaker for the self -starter ; a contact breaker for tin- two mag- netos; a triple led cock for the gravity ami pressure petrol; it triple led cock for the hand and motor air pump; a thermometer for the water of the radiator; the petrol gauge placed on the hack side of the main tank, and a m inoiiicti r for air pressure. To left: das lever; lever for regulation of the gas in altitude (lights; lever for operating the radiator Minds, clip for three light cartridges. On the lottom is further arranged a hand pump for the hydraulic machine-gun gear; two IIOM-S tor drums for the movable machine-gun and the sell starter. A .square windshield of Triplex glass is placed in front of the pilot's seat. li. hind it a box is arranged in a queer position to the body with access from outside. The ti\ed Vickcrs' machine-gun lies to left of the pilot inside tin- hodv fabric. The cartridge girdle is of metal. Tin- tiring of the machine-gun takes place hydraulic-ally bv mi-ana of a control arrangement, placed in front of tin- motor and connected with tin- in >. Inn. -mi through a cop per main, as well as driven from tin air screw bv a gear set. The firing lever sits on the stick. On the bow slnpi-d iron band lying on the centre ec- tion rests a Lewis gun. which can In- pulled down during the Higlit to permit vertical tiring. The empty weight of the a. roplanc was worked out at TOO kilos, distributed as follows: Kilos. 3.6 il o Knjrinr |-'.\li.nis| e.illn-tiiili Self-starter .... ;T Itiiiliiitnr water ... Air screw M.6 Main petrol tank 17.H ('rnvity |x-trol tank 6.4 Oil tank Mut.ir e<|iiipiiM-nt 6.4 Bixly with M-at ami plate rovers 141.0 Tail plate iiiijile of im iilener ehaiiftr arrangrmcnt 1.0 I 'nder carrinjfr 40.8 T,,il skid 3.7 I'ilntiipr arrangement 4.4 Planes with wirimj lli.3 Vertical and horizontal wiring il.O HcMlv equipment " 14.0 ;,.., The fuel weight amounts with fully loaded tanks to 1 1 1 kilos, so that the total useful load can be calculated at 250 kilos, the total weight working thus out at '.>:>< kilos: 9.16 The load of the planes is thus: =12 kilos per square metre. The performance load Is then: horse-power. !.> kilos per Tail plane incidence gear of the S. K. 154 ' TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING ^^IBH^^HHIH . - < i American S. E. 5 with 180 Hispano-Suiza S. E.-5 180 Hispano-Suiza BRITISH TRIALS The American machine of this name completed its tests under U. S. army supervision in 1918. For comparison, the summary of results on the British and American S.E.-5 is- given, as determined at Wilbui Wright Field: Summary of Results S. E.-5 (British) Climb (ft.) Time Rate R.p.m. Speed R.p.m 1,170 123 2,100 6,500 6 min. 50 sec. 810 1.800 118.5 2.080 10,000 11 min. 34 sec. 615 1,800 115.5 2,040 American S. E. 5 with ISO Hispano-Suiza Climb (ft.) Time Rate R.p.m. Speed R.p.m. 15,000 21 min. 20 sec. 340 1,800 10T.5 1,965 20,000 50 min. IT sec. 60 1,780 85 1.S20 Service ceiling 19,400 ft Total weight 2,051 Ibs Summary of Results S. E.-s (American) Climb (ft.) Time Rate R.p.m. Speed 6,500 10,000 15.000 20,000 8 min. 13 min. 22 min. 10 sec. min. 30 sec. 750 590 350 140 1.800 J,800 1.800 1,790 121.6 120 117 109 92.5 R.p.m 2,100 2,140 2,080 2,000 1,860 Service ceiling (where climb is 100 ft. per min.) 20,400 ft Total weight 2,060 Ibs A squadron of British aeroplanes, type S. E. 5 M\(;i.K MOTOKKl) AKK01M.. \.\KS -MM I ...'. i. J\* Stxaitli.'inelMn Jfinyxan en <7)>an>r i f !** I ,. ..!' J. ^ t 1*1 c- *< ^Ii x-x *. *. -*.r WlilllJ-lJ . .4 ft V "" J,,< .. v . I - -WH- .'. '/- W .../.- X ," - -36> w 1 I ** <0O *.- tt *'/ > .., v ..4.^. - -. .'..-.I Q >/-./. j *( .>'> *.**' 1 I * *.. r.4 . O IS !'*** ' . * . * * . .J* - V .>>--- --* . -* ***-.'* /.*.'.; j^-t-t r ini."- "f tin- Supwith Camel, cquip|)feeii prolific in its production of yp's. Tin- characteristics of oinr of tlir lati-st t\ pi -. an- re >rodticed herewith hy courtesy of It-rial .li/t- II <*3 - 43' \ ;*> o ||*C 44-0 O- 90 00 JJO 39 So 18 6 )6 60 } 6 7 o 5 7 S 6 4i*o 397*0 182-0 164*0 (115-0 346*0 'O *o 7 3 5 O 1 9 i J 1-3 - . . 43*0 13*8 1JJ-0 )2- 2 17- 210 4- 8-8 13- '. )aoA n i 04 ft 7 6 7 6 463-0 445*0 910-0 o 7 1 o o 3*o \ ?1 ' f* 4 s 4 1 245 34 ' ) Sp-M-rr " M,.o- cb*stcr 1 B 9 21 6c 6 9 & t 6 fi |6-0 46.-0 >08-0 o 4 >l o | o-o Ji-o 13 j 10-4 2V6 7 -t r'l Man- 37 O OO / o 7 w 1 24 o 69*0 38-0 IO7-O 16- tS-o J4-0 Chrtn 11 37 60 60 7 6 7 6 430*0 387*0 817-0 o 7 j 'i - 1*4-0 3O-O 33-0 83-0 It- 16-9 18-0 3041 31 I 3 36 4 10 4 10 I7O*O |6O*O J10-0 3 3 a > | *'i 43-5 -"--o TS-0 44*0 6* 90 13-0 SJIA 20 6 1 27 4 6 4 6 106 o 104*0 210-0 $ 4 1 x o 10 19-1 I7-J II -0 J8-3 O- 7-6 7 S Pojni'ai-" 1 S J 5 *5 1 4. *>t-o Hj-o tlo-o M 4 1 4 |*0 27 ( < y : O '1 ? 1 I Table of weights, etc., and performance Type of machine Engine. Weight of machine. 1| u. g. 3 &! Speed (m.p.h.). ( limb (in mins ) to I O f! f Load/h.p. P H.P K fl i '; It 9 | | | Type. . Q 8* finuis 6~ - it m p h. Ibs. Ibs. b Rk(5>3) Le Rh. 2 S. no 1,230 4.OOO 1,823 6.064 3 7 225 616 9 97 75 88 65 a -5 J 16 7 65 35 40 5*5 2 7*3 16.5 '5*9 530*. H.S. 200 1.685 2.680 4 432 III 108 '. '4 4t 18,000 45 8-23 '3*4 'M 2-H H.P. 44<> 4.361 7. '35 5**5 < 56 11*6 106 93 7 '7-3 35< 45 7*75 16.2 1.2)0 Spider(53i) C. 130 063 '.5'7 3 330 130 no i 9-5 22: 19,000 40 7*78 II. 6 "5 Manchester I 2-D. 640 4.079 6.586 5 - 75 700 128 122 "5 4 ; u 4 :oooo 45 8*06 10*3 Manchester II 2 P. 600 4.574 7.1 =,> 3-75 446 '15 119 I I : s 6. - 11.5 43i 17.000 45 8. 76 *9 1.074) 5041* C. 130 1,408 2,006 2 160 80 65 1 . *5 4 6.09 18.1 53'A C. 130 961 l.5'4 3 330 I2O i to. 5 103 4) 9 5 22: 19.000 40 7.22 IT. 6 Popular (534) G. 35 607 5 844-5J 3*5 "7 70 67l 621 2O 30 4 69* >4 1.1 I.e Rh. - Le Klione. S. - Sunbeam. H S. Hitpano uixa C - Ckrgei. D. ^ " .Dragonfly " A.B.C. P. - Siddcley " Puma. G. - Green. At lo.ooo ft. < To 18.000. J To 15.000. { To 1 7.000. | At 3.000. f At 5,000. THE ITALIAN 5.V.A 210 K> SPA MOTORED FIGHTING 5COUT CENTIMETIRS r ,'. M'Laajblj; 158 SIXCLK MOTOKK1) AKKOl'l \\KS l.V.t 'I'hr It >li in > V \ I ifilitiii): Tractor equipped with a Spa iOO h.p. engine and provided with two Virkrrs machine jcun. This ma- him- ran clinil) 10,000 fret in H ininiitcs with a military load of 500 |M)iincls The S. V. A. Fighting Scout The S. V. A. machines arc manufactured by Gio. An- vildo & Co., of (icnii;i. Italy, in a nunilicr of types quite similar to one another, the principal differences being in In- wing spread and weight. In nearly all the types, the inn- |>ropi-lli-r, motor and fuselage is used. With the ex- eption of one of the types, the interplane strut bracing at itlu-r side of the body is arranged in the form of the -ttrr A'. The machine is convertible for water use by re- l.'irinif tin- landing gear with twin floats, as illustrated in lie photographs. All tin- material used in the construction of these MM hiiics is trsted in laboratories before being installed, and gain rigidly inspected when the machine has been tested ut in actual flight. The woods are tested for transverse nd longitudinal tension and compression, etc. Cables arc nun .s to Id times as strong as calculations show them to * nri-i-ssary under extreme conditions. The silk-linen o\ triii;; is somewhat transparent and after being treated vith dope is practically untearable. Tin- dimensions given below accompany the drawing hown. General Dimensions ipan. upper plane 9.100 mm. (30 ft. 3 In.) ipan, lower plane 7,600 mm. (25 ft. in.) 'honl, both planes 1,650 mm. (5 ft. 5 In.) 1,800 to 1,500 mm. (5 ft. II in. 4 ft. 11 in.) Krrnll lenjfth H.100 mm. (i6 ft. 7 in.) Her .11 hei(fht 3^00 mm. (10 ft. 6 In.) ft'eijrht, emplj 640 kff. (1.411 His.) ijrht, loaded 900 kg. (1.9S4 UPS.) Motor, SI 1 \ ilO h.p. Maximum speed 33-3 km. (Hi ml.) p.h. Minimum s|>eed W km. (45 mi.) p.h. iTHmh in 14 min 4,000 met.-rs (i :,!.>: ft.) Main Planes The planes are in four sections. The top plane is a tl.-it span, but the lower plane sections are set at a dihedral Tin- wing curve has a negative tendency at the trailing edge, and the planes are given but a slight inci- dence angle or angle of attack. As in most of the fast Italian machines, the trailing edge is flexible, tending to flatten out the wing curve as the speed of the machine increases. A single set of ailerons are hinged to the upper plane. The steel-tube interplane bracing is of streamline sec- tion, and attachment to the swing spar is by a pin running through the end of the brace, parallel to the line of Might. The bracing method employed is such that both the lift and landing stresses are taken by the struts, eliminating the wire bracing cables. Drift and anti-drift cables are used in the usual manner. Main planes have a surface area of about -tl.'2:> sq. m.; the loading of the machine is about 36,7 kg. (about 81 pounds). Fuselage At the forward end of the fuselage, the motor is en- tirely covered in. and the cowling runs back in a straight line as far as the pilot's seat. The rear curves of the under side of the fuselage are composed of a series of straight lines, and not a continuous curve. A noticeable feature of the fuselage is its narrowness in the vicinity of the tail plane, and its exceptional depth forward. The interplane struts sloping outward from the fuselage are not connected to the upper longerons, but are carried part way down the vertical spacing members between the up|wr and lower longerons. Evidently a compression member is located at such points, running from one side of the fuselage to the other. Veneer is used for covering in the body, except at the front end, where the aluminum cowling covers the en- gine. Tail Group The leading edge of the tail plane is located at the level of the center of propeller thrust, as indicated on the draw- 160 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Official photograph. View of the body assembling and covering department of the Ansaldo factory, one of the largest Italian aeroplane factories ing by the dotted and dashed line, and the plane is fixed at a negative or depressing angle. It will be noticed on the plan view of accompanying drawing that the tail plane, or hori/.ontal stabilizer, is exceptionally small, its area l.eing only slightly more than half the area of the elevators or tail flaps. The flaps are worked with short control tillers located close to the body. A pair of steel struts support the tail from the fuselage. The familiar triangular fin OP vertical stabilizer is used, with the rudder hinged to its trailing edge. The lower end of the rudder is carried in a cupped metal fitting at- tached to the under side of the fuselage termination. Control wires run into the body through protective metallic plates with friction-reducing guides. Landing Gear Steel tube chassis members carry the floating axle, cross wired in the usual manner. The shock absorbing rubber elastic is covered in to reduce skin friction. The tail skid is unusual inasmuch as it relies upon a steel leaf-spring skid for its shock-absorbing effect. The upper end of the spring is rigidly clamped to a metal con- tainer, from which supports are run to the upper longerons of the body and to the tail plane. Motor Group The engine is a 6 cylinder SPA developing 210 h.p. at 1600 revolutions per minute. The propeller is 2750 m. (about 9 ft. in.) in diameter, with a 2100 m. (6 ft. 11 in.) pitch. Gasoline is carried for an endurance of 3 hours, weigh- ing 105 kg. (231.48 Ibs.) and oil weighing 15 kg. (3:!. 06 Ibs.). General In the empty machine, the weights are distributed as fol- lows: Machine unequipped, 300 kg. (661.38 Ibs.) ; motor, propeller and radiator, 315 kg. (691.45 Ibs.); fuel tanks and the necessary piping, 25 kg. (55.11 Ibs.). Total weight 610 kg., or 1410.95 Ibs. The useful load consists of oil and gasoline weighing 120 kg. (264.55 Ibs.) and an additional useful weight of 140 kg. (308.65 Ibs.). The loading of the machine per b.h.p. is equal to approximately 9 Ibs. This type of S.V.A. machine is also manufactured in what is called the " reduced size," in which the wing span is shortened to 7570 mm. (24 ft. 10 in.) but otherwise lire- serving the lines of the " Normal " type. In the smaller machine, the total weight of the machine is 875 kg. (1929.04 Ibs.) instead of 900 kg., and the loading on the surface is 39.300 kg. (87 Ibs.) instead of 81 Ibs. as in the " Normal " type. With the smaller machine, the same powered motor, and a change in the angle of incidence of the planes, a much greater speed is obtained. SINCiLK MOTOKKI) A KKOI'l . \ \ I > The Pomilio Reconnaissance Type Tractor 161 I ili m I'liniilin ICi-i otiiiaissance ami llomliarilmcnt Arroplanr. \pparatu- i- r.irrird fur thr releitM 1 of honili-. mill n movahle iiiafliiiir-^nii h iiiiiiuilfil at th* rrnr ruckpit I: \i.'w MII. height, l'-"s overall li-ntflh, 30'-O" M- l-oiinlio Hrconn.nss,,,,-,- and Boml.anlmrnt Tractor s M-en from UK- M.lr. ()ffi.-ial lrst> |,ae shown Ihi- innrhine to Iw .hie of a horizontal speed of 1*0 miles an hour. Its rlimh is also very good, an ascension ..f .'.' minutes 162 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Gravity Tank A.E.G. ARMOURED AEROPLANE Span 4*' 6' Chord S' 4* Gap V6' Tail Plane Span ' o* Overall Length 3' 7 f Engine (" Benz ") * Propeller- 'o 7 3* inn \\i Tn|i: Three-quarter front view. Tin opening in tin- top pl.mr for thr raili Jilur mill petrol serxiee tjnk should lie niiti-il. Itnttiiiii: \ i. fniiii jili.ue. shoxunjr in ilin|!raiiiiiijitic form tin- cnn slriictioii of top plane. IIIM-I: The t.iil (The German Ago 8 regards its general lines, tlic Ago is of a striking unusual appearance, mainly, no doubt, due to the fact that its wings are tapered very pronoiitiredly from nmt to tip. This is very unusual in any modern, and when it is suddenly met with in a German machine of compara- tive recent date from various marks on tin- machine one gathers the impression that it was built certainly no longer ago than the first months of 1917 the question that first comes to mind is naturally enough related to the raiton d'etre of this uiiusu.-il design. In the first pl.-ice. it is ohvious that whatever it was the _ncr was aiming at. he was prcp.-ircd to go to consid- erable trouble to ohtain it. since the construction of sueh "d wings as those of this Ago are not by any means n attractive proposition commercially, entailing, as it the separate construction of half the ribs, no two > liieh arc alike from root to tip in one wing. Also M the spars converge to a point at the tip. they intersect the ribs at varying distances from root to tip. which again \ Fighting Biplane iiie.-iiis extra work in manufacture. Ax for the spars themselves, (hex also taper from root to tip. again more trouble and expense. When .standing in front of the machine one is at once struck by the peculiar bracing of the front spar. In- stead of the usual interplane strut there is on tin only a single solid wire running from the front lower spar to the front top spar, while no lift or landing cables of any sort are employed Ix-tween the two front spars. This feature, then, will probably IK- found to contain (lie solution of the peculiar design. By doing away with the front bracing, a much freer field of firing is obtained, and there can be little doubt that this was the object for which the designer was striving. Owing to the backward slop, of the leading edge of the planes, the outer inter-plane struts are farther back than they would be in a machine with straight wings, and also owing to the taper, closer together and therefore obstructing the field to a smaller extent. The narrower 166 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Some constructional details of the Ago biplane. 1. Dimensions of lower front spar near body. 2. Attachment of tubular struts to fuselage longerons. 3. The hardwood distance piece at the crossing of the internal wing-bracing cables. 4. Section of the lower front spar at the point of attachment of the interplane wire. 5. Perspective sketch of same joint. 6. Section of rear spar. 7. (A) construction of false spar and aileron leading edge; (B) An aileron rib (not to scale); (C) Aileron crank and attach- ment of inter-aileron strut chord near the tip will result in a smaller travel of the centre of pressure, hence possibly the twist on the wings may become less, and the absence of front bracing be a less serious defect than one is inclined to imagine at first. When we say absence of front bracing, this is not quite correct, since, as already indicated, a single solid wire runs from top to bottom front spar. As is well known, in biplanes, with top and bottom planes of the same area, and with the conventional spacing of gap about equal to chord, the top plane carries about 30 per cent, more load than the bottom one, or roughly, 4/4 and 3/7 respectively. By running a wire from the top to the bottom front spar, the latter is therefore made to carry a certain share of the top spar's load, thus relieving, to a certain extent, the enormous bending moment that must be present on a com- paratively heavily loaded machine, whose front spars have a distance of some 13 ft. 6 in. between supports. So much for the general design of the Ago. As regards the construction there is much detail work that is inter- esting and unusual. The fuselage which is, as in the majority of German aeroplanes, of very roomy propor- tions, as regards occupants' accommodation, is covered with fabric except the front around the engine, which is covered in the three-ply. The floor of the fuselage is of three-ply from the stern to the gunner's (rear) cockpit. From there to the nose the floor is three-ply, covered with aluminum. In. section, the fuselage is rectangular, a light and comparatively flat structure forming a turtle back over the top of the main fuselage framework. This turtle back is built up as a separate unit, and is easily detachable by means of a neat and very simple clip. In case of severe stresses being put on the fuselage, it is therefore an easy matter to detach the top covering and examine and adjust the internal bracing. The four longerons, which are of square section, are pine, from the rear cockpit to the stern, while in front they are made of ash. The struts are in the form of steel tubes and the solid wire bracing is attached to the struts in the manner shown in one of the accompanying sketches. A small socket apparently machined out of the solid steel bar, has holes drilled in its edges, through which the bracing wires pass. This socket is slipped over the end of the tube, which has small dents in its end to give more room for the loop of the wire, and the socket, with its strut, is secured to the longeron by a bolt passing through it, with the nut and a spring washer in- SIXCLK MOTOKKI) AKKO1M.AM - KIT sitle tin- socket, as shown in section in mil- of our sketches. Kxcept for the fact that the longeron* arc pierced by two lioles the horizontal and vertical fuselage struts are .staggered in relation to one another close to one an- other, this arrangement appears to ! \rr\ neat, and cer- tainly takes up very little space. In front, the fuselage bracing is in the form of diagonal steel tubes, no wires bciii'j employed. The rear eoekpit is ivcupicd li\ th<- nrichinc gunner, who is seated on a small seat built up of a framework of steel tubing, over which is stretched canvas. This seat is .so hinged and sprung that immediate ly the gunner stands up the seat springs into a vertical position out of his way in case he wishes tu times greater than that of a diagonally wired fuselage of the same outside dimensions, and having members of the sire usuallv employed in structures of this type. The landing resistance nl the Miner type of body appeared to be greater than that of a cross wired fuselage of the same weight, although no actual figures were given showing how much greater. When looking into the detail construction of the Alba- tros body the first thing that impresses one, apart from the absence of internal cross bracing, is the extensive use that has been made of veneer in the construction of the tratist erse bulkheads or formers, which take the place of the struts and cross members of the girder type of Univ. In Fig. 1 are shown the different bulkheads of the body, with dimensions, etc. The rail half-way up the sides of the body is placed parallel with the propeller shaft, thus serving as a datum line from which to make measurements of distances and angles. In order to better form a conception of the Alb.it ros construction we have shown, in Fig. 1, half-sections of the more important and representative bulkheads. In the front portion of the Itody the bulkheads, which here have to take the weight of the engine, are about I ' ( in. thick, and are made up of a number of laminations of wood, which are, of course, so placed in relation to one mother, that the grains of adjacent layers run at angles to one another. Fig. ' sin. MS the nose of the Albatros, and clearly in- dicates the method of supporting the engine. The first bulkhead, it will be seen, is solid, and in at right angles to the propeller shaft. The second bulkhead 2, Fig. I is lightened by piercing as shown, and is also vertical, while the third engine .support is formed by a solid bulk- head 3, Fig. 1 - which slo|>cs back no us to support the front chassis struts and front cabane .struts at its lower and upper ends respectively. As the front engine support is clearly shown in the sketch. Fig. '. it has not hi en included in Fig. 1. The bulkhead numbered 1 in rtlon. of torn* of tb* mora imponul bulkh. of tb* Albttro, nhtin blpUux. 172 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Fig. 1 is merely a former, and does not help to support the engine bearers. These are of I-section spruce, and have plywood flanges top and bottom as shown in Fig. 3. The upper flange is continued outwards to the middle longeron so as to form a shelf or bracket at the sides of the engine. A construction somewhat different to that of the engine supports is employed in the panel between the pilot's and gunner's cockpits. This consists (4, Fig. 1) of a spruce framework faced each side with 3 mm. three-ply, the whole having a thickness of 26 mm. (about 1 in.). Be- hind the gunner's cockpit is a light partition built up as shown in 5, Fig. 1. Two light spruce struts run diagon- ally across from corner to corner of the bod}', crossing in the center of the fuselage at which point they are rein- forced by three-ply facings and triangular blocks glued into the corners. Their attachment to the upper and lower body longerons is of a similar construction, and will be clear from the diagram. On their front faces these diagonal struts are provided with a 2 mm. flange to stiffen them against buckling. A canvas curtain is secured to the front of this partition, having in it pockets for maps, etc. From this point back to the front where the tail plane and vertical fin are attached the formers of the body are in the nature of a very light framework of thin struts, a typical one being shown in 6, Fig. 1. The general con- struction and some of the dimensions of the various mem- bers will be clear from the illustration. One of the features in which the present Albatros dif- fers from previous types is the construction and attach- ment of the tail plane and vertical fin. The latter is cov- ered with three-ply, and is made integral with the body, out of which it grows, so to speak. The construction is shown in 7 and 8, Fig. 1, and in the perspective sketch, Fig. 4. The tail skid is supported on one and sprung from the other of these two bulkheads, as illustrated in Fig. 5 (below), the general and detail construction of it being evident from the sketches. The tail plane is provided with hollow spars which fit over cantilever beams integral with bulkheads 7 and 8, Fig. 1, the details of which arrangement will be dealt with later. Having dealt with the bulkheads or transverse parti- tions of the Albatros fuselage, the longitudinals rails will be considered next. These are of a somewhat compli- cated nature, varying as they do along their entire length, not only as regards being tapered from front to rear, but also in the different form of spindling out employed at the various points, and in the method of reinforcing with other strips of wood, partly in order to increase their strength where required and partly to make their overall section conform to the various angles and curvatures of the outside three-ply covering of the fuselage. From Fig. 6 a fairly good idea may be formed of the shape and dimensions of the longerons at various points. The lower one (left hand) is originally of rectangular section, but is lightened from point to point by various forms of spindling and stop-chamfering. Thus at the point B (see key, diagram Fig. 6), the inner face of the bottom longeron is spindled out on its inner face with a curved cutter. At other points of this longeron farther towards the stern various sections are met with, as chan- nel, solid rectangle, and L sections of various proportions. Between the horizontal stern post and the point at which the middle longeron meets the lower one, the latter is re- inforced with a triangular section strip, so as to carrv the three-ply covering into the sloping side. Similarly at the section A, Fig. 6, the longeron, which is here of solid rectangular section, is reinforced on the outer side with a curved trip, spindled out externally, and with a smaller strip on the lower face of the longeron. The upper longeron, which is originally of rectangular section, is spindled out to channel and L sections at va- rious points, as shown in X, Y, Z, Fig. 6. So as to form Fig. 5 The tail skid and its at- tachment on the Albatros biplane. SINCil.K MOIOHK1) AKUOI'I \\| - Fig. 2. Sketch showing engine bearers of the Albatros biplane. Fig. 3 Section of the engine bearer* of the Albatros biplane. Fig. 4 Con- struction of toe vertical fin 174 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING fiitir g" (F g General arrangement of the Albatros body. Side elevation and plan to scale. an attachment for the curved top of the body, the top longerons have glued to their upper face additional strips of triangular section while at the point Y, Fig. 6, the sec- tion is left rectangular so as to form a support for the gun ring. In addition to their function as strengthening members these strips serve the further purpose of pre- venting the bulkheads from sliding along the longerons, as they are cut off where a bulkhead occurs, against the front and rear sides of which they abut. In some places, as for instance in the front of the body where the cover- ing is in the form of an aluminium cowl over the engine, the strips are omitted and the cowl attached to turn-but- tons as shown in the sketch Fig. 1. At such points the bulkheads are prevented from sliding along the longerons by a long wood screw passing horizontally through the longeron into the bulkhead. The middle longerons, which, as already pointed oul in a previous article, are horizontal, i. e., parallel to the propeller shaft, are of smaller overall dimensions than are the four main longerons. They are rectangular section lightened in places by stop-chamfering, as shown in a and b, Fig. 6. Fig. 8 shows, in side elevation and plan, the genera arrangement of the fuselage, and should, in conjunctioi with the various sections and key diagrams, explain fairlj clearly the general layout of the body. Where the tai begins two extra longerons on each side have been buill into the bulkheads of the body. These two short longer FiJ. 9. Sketches of the tall plane and its attachments oh the Albatros biplane. SIN(;i.K MOTOKK1) A Kl >1M A \ I - 17.-. ons have, in |)l.-in. a direction parallel tn tin- lint- of Hight, while tin in.-iin longerons continue cm their converging course. Tliis arrangement is indicated in tin- plan view K. In side elevation tin- short longerons, against which lie the inner ril>s of tin- tail plane, have the same ciir\ature a- the tail plane. In this manner the lines of the rear part of the body are not spoiled, while an easy flowing eur\e is prox ided for running the tail plane into the bodv . Keferenee lias already been made to the peculiar attach- ment of the tail planes to the body. The sketch at the top of l-ig. !' shows in perspective this attachment, which is also illustrated in the diagram in the Imttoni left-hand corner of Fig. >. The bulkheads of tin body are extended outwards tn form cantilever heanis which support the tail plane. There are three of these cantilever beams, while further support is provided for the tail plane leading and trailing edges as indicated in the sketches. The .spars of the tail plain- are of the box tvpe. built up of ash flanges with thin three-ply sides, eut out for lightness. These spars an s,i proportioned that they rit over the cantilever beams, which do not. it will be seen, run right out to the edge of the tail plane, but are finished off just outside the second tail plane rib. No external braeing of the tail pi me is provided, the depth of it and the method of mount- ing being relied on for the necessary strength. To pro\ idc against the tail plane sliding off its canti- lever supports it is secured at the leading and trailing due. The former attachment is indicated in the bottom right-hand corner of Fig. 9. A sheet steel shoe fits over tin corner of the leading edge and inner rib, and through this shoe a long bolt passes, which runs across the body to a similar shoe on the other side. In Fig. 10 is shown the rear attachment of the tail plane. A sheet steel box sur- rounds the corner of the fuselage. Welded to this box is a short tnlx- which tits into n circular recesi in the end of the tr.iiling edge of the tail plain-. As tin- elevator tulx- runs right across and is fitted with collars Ix-aring against the sides of the clips that form the Itcaring for the elevator tube, the trailing . -dgc of the tail plane is prevented from slipping outwards. The manner employed of forming bearings for the > I. vator is indicated in the diagrams of Fig. 1O. A steel strip is Ix-nt over the tube, and its two free ends are Ix-nt over and tit into slots in the trailing edge of the tail plane. Each clip is tin n secured to the tail plane by a vertical bolt as shown in the diagram. The trailing edge of tin- tail plane is spindled out to a si-mi circular section as shown, and a curved metal distance piece is screwed to this trailing edge or spar, so an to form tin second half of the bearing of which the bent steel strip forms the other half. To remove the elevator the bolts securing the clips are undone; the clips are then bent outwards until their free ends clear the slots, when the elevator can be removed bodily. As the elevator i.s built of steel tubing throughout, wood I'hi. ks of the shape shown in detail I, Fig. 10, are em- ployed for attaching the fabric covering. These blocks span over the steel strip bearings, and are secured to the tubular leading edge of the elevator by screws as shown in section Ml!. A hole in the opposite wall of the tube serves for the insertion of the screwdriver. As regards the remaining details of the tail of the Alba tros little need be said, as they are fairly evident from the plan and sections of Fig. 11. It will suffice to point out a rather ingenious construction of the leading edge of the tail plane. In plan the tail plane, it will be seen, is roughly semi-circular, and its leading edge therefore has to be shaped to this curvature. As an ordinary strip of .solid spruce spindled out to a semi-circular section would Flft. 10. DcUiK of the tail plane and elevator attachment on -the Albatro* STEL CLIP \ x-~-'Lx JeerntM A .A DETAIL/. 176 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING ALBATROS TAIL PLANE Fig. 11. General arrangement and dimensions of the members of the tail plane on the Alb*tro biplane. scarcely be strong enough for this work, a different method has been employed. It appears that originally the lead- ing edge of the tail is made up of four laminations of ash, having, of course, their grains running in slightly different directions. The rectangular section spar thus formed is then spindled out to a semi-circular section, as shown in the diagram, leaving the impression that the leading edge is made up of seven thin strips of wood glued together. The resulting leading edge appears to be one of great strength, while at the same time being quite light. The cockpits of the Albatros are arranged in the fash- ion now universally adopted for two sealers, by Allies as well as by the enemy, i. e., the pilot in front and the gun- ner in the rear cockpit. The pilot's seat is mounted, in the Albatros, on the main fuel tank, which has two an- nexes on top, one on each side of the seat. This arrange- ment is clearly indicated in Fig. 12, in which the small clips preventing the seat from sliding about on the tank will be noticed. The filled cap is mounted on a tubular projection extending through the fuselage covering, thus enabling the tank to be refilled from the outside. A smaller auxiliary tank is mounted above and to the rear of the main tank, in the gunner's cockpit, as a matter of fact. Botli tanks are connected up to a by-pass or dis- tributor, so that both or either tank can be connected up to the engine, two pumps being provided for maintaining the necessary pressure, one driven by the engine and the other hand operated. Thus, whatever tank is being used, petrol is fed to the carburetor under pressure. This has probably been a necessary provision, as the tanks are placed relatively low and gravity feed would, therefore, be apt to be unreliable when the machine is climbing at a fairly steep angle. Constructionally the petrol tanks are of interest in that they have been internally braced by rods running across from side to side, the attachment of the rods being visible Eiifi on the outside of the tank as shown in Fig. 12. To pre- vent the petrol from slushing about inside when the tank is nearly empty baffle plates are fitted dividing the main tank longitudinally into five compartments, communicating with each other through the circular openings shown in the section of the tank, Fig. 12. As the supply pipe leaves the tank fairly high up it can be seen on the front right-hand side of the tank in Fig. 12 it is carried down inside to the bottom of the tank so as to enable the last drop of petrol to be forced out and into the carbu- retor. The main tank is mounted on brackets as shown in one of the sketches, and is secured by metal straps hav- ing an arrangement for adjustment. In Fig. 13 is shown the general arrangement of the controls. There is a transverse rocking shaft at each end of which are mounted crank levers for operating the elevators, while in the centre, pivoted so as to be free to rock laterally, is mounted the main control lever. Mounted on the transverse shaft, but not moving with it, is another lever, which operates the claw brake mounted on the wheel axle. The arrangement of this brake is shown in Fig. 14. By pulling the lever the free end of the claw brake is pulled upwards, thus causing the claw to dig into the ground. On releasing the lever, the brake is returned to its normal position by the action of the spring shown in the sketch. The transverse rocking shaft is carried, as indicated in Fig. 14, in two bearings mounted on the lower longerons. A forward and backward movement of the control lever causes the shaft to oscillate, and with it the two crank levers to which are attached the elevator control cable. SI\(;i,K MOTOKKI) AKUOl'l. \\ l.s 177 Tin -sr cables run from (lit- crunk lever, around a pulley slightly forward of the transverse -.halt a-, shown in the sketch, anil hence to tin- top crank ICMT on tile elevator. Tin- return calilc runs from the crank on tin under side nt tile elevator to tile crank on the transverse shaft. Kn route these cables pass over pulleys Iiloiilited in the rear position of the fuselage, these pulleys hcina shown ill detail in sunn of the accompany ing sketches (Fig. 15). As regards literal control, the general arrangement of this is indicated in diagrammatic- form in Fig. 16. From the control lever the direct cahlc passes over a pulley on the transM-rse shaft, along through the lx)ttom wing, around another pulley in the wing, and hence to the rear half of the aileron crank le\er. The return ealile runs from the front half of the aileron crank lever, around .mother pulley in the lower wing, through the wing and through the transverse shaft to a pulley on the other side of tin' control lever, and hence to the screw on the con- trol lever. The details will he clear from Fig. 13. The foot l>ar operating the rudder is mounted on a pyra- mid of steel tulies, and the rudder cables arc taken, not, it will In seen, from the foot bar itself as is generally done, hut from a short lever projecting forward at right angles to (he foot har. From this lever the cables pass over pulleys and to the cranks on the rudder. It will be seen that provision has been made for making adjustments of the loot bar to suit pilots of different height by fitting on extra foot bar. As in the majority of German machines, provision has 1'ei n made for locking the control lever in any position either Hying level, climbing, or descending. This is ac- complished ly means of a collar free to slide along tin control column, but U m- split and provided with a bolt for tightening up. when the collar is locked in position on the control column. Anchored to this collar by two screws is a fork end. from which a tnU runs dou n and forward to terminate in a ball rind socket joint secured to the bottom of the fuselage. This ball and socket joint, it will In- set n. enables the control column to be moved freely in any direction, and to allow it to I*- moved from side to side, even when the forward movement of the column is prevented by locking the collar. In this manner, the pilot can lock the elevator, while operating the control column from side to side for lateral control with his knees. While on the subject of controls, reference might IM- made to the crank levers on the elevator and rudder. These are shown in Fig. 17, from which their construc- tion will be evident. The crank lever of the elevator has projecting from it a tapering tube running to the trailing edge of the elevator. The tubular rudder post is working in bearings similar to those described in our last issue when dealing with the hinges for the elevator. At the bottom the rudder tube fits into and is supported by a socket carried on a clip bolted to one of the transverse bulkheads of the fuselage. A peculiarity characteristic of the Albatros is the method of attaching the control ca- bles to the crank levers. A socket is formed in the end of the crank lever, and into this fits a cup- shaped piece of steel machined on one of the bolts of the wire strain, r*. Fig. 14 Dlaftrmmatic ktcb of the claw brk on tb AJbtro. Ki(r. l:t. Tin- controls of I In- Ailmtros liiplnnr. Inset* show the hnll anil socket joint for thr control l.-v.-r locking arrangement, and hand grip with pin trigger on the main control lever. Fig. 16. Diagram of the aileron control system of the Albatros Fighter Fig. 15. " A " shows the pulley over which the elevator cable passes after leaving crank lever on rocking shaft (See Fig. 13). "B" The pulley mounted on the top longeron (in front of the tail plane) over which the elevator control passes. "C" This pulley bolted to the middle longeron just ahead of the tail plane guides the elevator cable. " D " This pulley guides the rudder cable in front of the footbar. Fig. 18. The machine-gun and its mounting on the Albatros Fighter. The bag for the spent cartridges should be noted. When not in use, the butt of the gun rests in the clip shown. The two smaller sketches show the locking devices for the gun pivot (left) and the gun ring (right) Fig. 19. So as to be out of the way when the gunner is firing from a stand- ing position, the seat on the Albatros Fighter is hinged and sprung as shown in this sketch Fig. 17. Elevator and rudder crank levers on the Albatros biplane. (A) Elevator crank lever with its ball socket joint for the turnbuckle. (K) Bottom rudder bracket and crank lever. (C,"\ Mounting nf HIP rmlHcr SIM.l.l. MOTOKKD AI.KOl'L. \.\KS IT'.t t-'if. ii. Shrrt strrl s|uir IHIX and socket fur compression tulw i>f the up- |MT pl.im- of tin- Mli.-itrus liipl.mi- I In- Uittniii skrtch shows the ;itt.-i. liim-nt of the terminals for the Interplane cnMcs ami struts = ctlons ..I Hi leading edge, in 'in spurs nnd false spar of the AHwtros liiplime nuu-li in tin- same manner .-IN the terminal attachment of tin main lift cables. Thus any vibration in the cd f tin- turn-buckle bolt being free to move in it* sin k. t in tin- crank lever. n nee has already been made to one part of the armament of the Alliatros. namely, the s\ nchroni/.ed ma- chin, -mi op. rated by the pilot from the trigger on the main control column. In addition there is a movable ma elnni i;un mounted on the usual gun ring in the rear cock- pit. Tin- a< n. ral arrangement of this gun mounting is slion in (I,, sketch. Fig. 18. The gun ring itself is built up f thin three-ply wood, and runs on small rollers on its support so as to reduce friction. It is prevented from tilting up by wooden angle pieces screwed to its undcr- siil.- and overlapping the fixed support. The machine-gun is supported on the gun ring l>\ -i swivelling fork, which can be raised and lowered as re- quired, and which can be locked in any desired position by the locking arrangement indicated in the sketch of the general arrangement. In addition to its circular mm. ment integrally with the gun ring, the machine-gun may be swung laterally on its pivot in the gun ring. Her.- also a locking device is provided in the shape of a split collar locked by an I. bolt, as shown in one of the insets. The other inset in Fig. 18 shows the lever by means of which the gun ring is locked in any desired position. As presumably it frequently happens that the gunner t. Corl mntftmtat of the .pp.r fcrft-bwxl wing at ln AIbtro. blpte*. to 180 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING wishes to fire from a standing position his seat has been so arranged as to swing into a vertical position as soon as it is relieved of its weight. This is accomplished by means of a spring under the seat, as shown in Fig. 19, which is, we think, self-explanatory. A strip of wood runs transversely under the seat and projects a short dis- tance on either side. These projections rest, when the seat is in a horizontal position, in brackets secured to the sides of the fuselage. The Albatros biplane belongs to the C class, that is to say, is a general utility machine variously used for fighting, reconnaissance, artillery spotting and photog- raphy, and is therefore not to be considered a bombing machine. It is, however, provided with racks for a small number of bombs four, to be exact - presumably by way of cases of emergency when a suitable target might present itself. Fig. 20 is a diagrammatic perspective view of the bomb racks and bomb release gear. The bombs are secured underneath the main tank in the pilot's cockpit, but they are released by the gunner in the rear cockpit by means of a small lever and quadrant shown in Fig. 20. The bomb racks are in the form of sheet steel sup- ports, against the bottom of which rest the nose and the tail of the bombs respectively. These brackets are se- cured to transverse members in the bottom of the fuselage, which have been omitted in the drawing for the sake of clearness. The bombs themselves are supported by a steel strap or band, passing underneath and approximately under the middle of the bombs. At one end the straps are hinged, while at the other they are provided with an eye, which is secured in the hook under the release trigger. One of the sketches in Fig. 20 shows in more detail the hook in which the eye of the strap rests, and the trigger by means of which the strap is released. The trigger is pivoted near its centre, and has an upward projection to which is attached a small coil spring resting in a groove in the base supporting the hook. When the cam on the transverse shaft presses down the rear end of the trigger, the front end moves upward against the tension of the coil spring mentioned above, thus releasing the strap and with it the bomb. As regards the cams which operate the bombs, these are mounted on a transverse shaft running across the bottom of the fuselage. There are four cams, each operating its trigger, but the gearing of the camshaft is such that it requires five pulls on the lever in the gunner's cockpit to rotate the shaft through a complete revolution. One of these pulls of the lever has no corresponding cam on the shaft, and has, it appears, been incorporated in order to provide an equivalent of a safety catch. When all the bombs are in place the first pull on the lever does not release a bomb, but merely brings the cam for bomb No. 1 into position, ready to press, on the next pull of the lever, the trigger for the first bomb. This has evidently been done as a precaution against accidentally releasing a bomb until the machine is approaching an objective. We now come to consider the method of operating the transverse camshaft. Near the right-hand side of the fuselage there is mounted on the camshaft a small ratchet having five teeth, as shown in Fig. 20. On this ratchet is a small cam, roughly of cone shape. This cam engages with grooves in the pulley around which passes the operat- ing cable. A small leaf spring engages at the proper mo- ment with the notches in the ratchet and prevents the shaft from rotating in the reverse direction. One end of the operating cable is attached to a coil spring secured to the side of the fuselage, and passes from there around the pulley to the lever in the gunner's cockpit. Assuming that the first cam is in position ready to release its bomb, a backward pull of the lever rotates the pulley and with it the ratchet and camshaft, thus pressing down the trigger of one of the bomb racks and releasing a bomb. When the gunner releases the lever this is pulled forward to its normal position by the spring on the side of the fuselage. The little leaf spring engaging with the ratchet prevents this and the shaft from following the pulley round in the opposite direction, and the cam on the ratchet sliding up the sloping bottom of one of the five grooves in the face of the pulley forces the pulley away from the ratchet against the compression of a small coil spring shown in the sketch. By the time the lever has reached its for- ward position, the pulley has revolved to sucli an extent as to bring the cam on the ratchet into the next groove in the pulley, and when the lever is again pulled the whole action is repeated. The sketch will probably help to make the action clear. In addition to a bomb release lever, there is in the gun- ner's cockpit another lever, the function of which appears to have been to engage and disengage a clutch near the engine, by means of which a drum is operated carrying the aerial of the wireless. In the bottom of the gunner's cockpit, near the left-hand side, is an octagonal opening in the floor, in which, so far as we can make out, the camera was mounted. The compass, so as to be visible from both cockpits, has apparently been mounted in a circular opening in the right-hand lower main plane. We now come to deal with the wings of the Albatros. These are, generally speaking, of the construction favored by the Albatros designer, that is to say, the front spar is well forward close to the leading edge, and the rear spar is approximately half-way along the chord. In addition, there is a third false spar, which is not, however, con- nected up to the body nor supported by any struts, and which cannot therefore be considered as taking any par- . ticularly important part of the load. It 'will, therefore, be realized that the rear main spar may at small angles of incidence, when the centre of pressure moves back-J wards, be called upon to support all or nearly all of the load. This has evidently been guarded against in the Albatros by making the rear spar of generous proportions. Both main spars are made of spruce, and are of the box type, consisting of two halves spindled out and glued together with a hardwood tongue running through both flanges. The ribs are of I-section, with spruce webs and ash flanges. Between the main spars false ribs are em-] ployed half-way between the adjoining main ribs, so as] to better preserve the curvature of the wing for this dis- tance. The general arrangement of the upper left-hand wing is shown with dimensions in F'ig. 21, from which the gen-j SI\(;i,K MOTOKKl) AKKOl'L. \.\I.S Ihi i ral lay-out of tin- wing will he clear. Tin- intrrn;il drift wiring is in the form nl the Lays, tin- i-iiiii|irrssiiiii struts fur this wiring being in tin form of circular section steel tulii-s. Iii the two nun r l>.i\s both drill :uid anti-drift wins arc in duplicate and arc approximately 1 l i S.\\'.(i. Tin nc\t two hays !ia\e single wiring. ,-ilso of 1 v! S.\\'.(i., while the outer Itay has single wiring of I 1- S.W.G. The attachment for the compression tulies and tin- drift and anti-drift wires is shown in Fig. 22. A box of thin sheet steel surrounds the spar at this point and is bent o\er and liolted as shown in the small section in Fig. 22. On the inner face of the spar this sheet steel box has two wiring plates stamped out. which receive the drift and anti- dritt wires. A short cylindrical distance piece is welded on to tin lio\. and around this tits a short tubular sleeve held in position by a slit pin. This sleeve forms a soekct for the tubular compression strut. Vertically the spar is pierced at this point by three holes, for the holts securing the interplane strut and the two interplane cables. The attachment for the latter is shown in Fig. _>,'. The base plate has machined in it two recessed circular openings which receive the two terminals for the cables. These terminals are prevented from ro- tating by a small rivet as shown in the sectional view. In order to further strengthen the spar at the point win-n- it is pierced by these three bolts, the spar ia left solid for a short distance on each side of the box, and packing pieces an- interposed between the box and the spar, so as to bring it up to an approximately rectangular section in order to get the bolts coming through the spar and base plate at right angles. In 1'ig. .':> are shown sections, to scale, of the two main spars, the false spar, and the leading edge. The trailing edge is. as in the majority of German machines, in the form of a wire. Fig. ' t shows the shape and dimensions of the wing section. As in nearly all German machines, the camber is. it will ! seen, extremely great, both as regards the upper and lower surface. The precise object of employing such a wing section is not at once apparent, but it should be remembered that the German machines carry a comparatively great load per square foot of wing surface, and the probabilities are that the section has been designed with a view to enable the wing to support this high load at comparatively great altitudes, and has, therefore, probably an excess resist- ance at lower levels. In addition to the general construction drawings of the Albatros wings, shown in a previous illustration, we are able to gi\e some of the more interesting constructional de- tails. Fig. 26 shows some details of the upper left-hand wing near the tip, and also the general arrangement of one of the ailerons. As will be gathered from the sketch at the left top of Fig. '<>. the wing flaps are built up of steel tubing throughout, and each aileron is balanced by a for- ward projection, not. as in the dothas. outside the tip of the main wing, but working in an opening ill the main plan.-. As in ne.irly all German machines, the aileron is not hinged to the rear main spar, but to a third false spar situated between the rear main spar and the trailing edge. The method of hinging the aileron will U- clear from the detail section and elevation at A. A. st.cl clip is bent o\cr the tube of the aileron and has its forward ends bent into grooves in wood blocks on the front face of the spar, much in the same manner as was employed in the ease of the elevator hinge ami di-scriln-d when dealing with that member. As in the case of the elevator hinge the fabric covering of the wing flaps is attached to wood blocks screwed to the tube. The crank lever for operating the wing flap is in tin- form of an elliptical section tube tapering towards its ends. I'.ach half of this crank lever carries three wiring clips, as shown at li. It will be seen that by providing three clips on each end instead of one. a means for varying tin- gearing of the wing flap control is furnished. If a pilot wishes the machine to be fairly sensitive on the lateral control he will naturally attach his wing flap cables to tin- inner clips, since thereby a movement of the control lever will result in a larger movement of the wing flap. On the other hand, if be prefers to have a large movement on his control lever without too great corresponding angu- larity of his wing Haps or ailerons. In- will attach his cables to the outer clips, as this will result in a " gearing down " of the wing flap. The forward end of the wing flap crank lever works in a slot between two closely spaced ribs, as shown in the sketches. At this point the ribs are strengthened by mak- ing them of the box type for their rear portion, and the ash flanges of the ribs arc left wider over this portion, while being reduced to their normal width from the rear spar forwards, as indicated in the sketch. At this point also occurs the strut and lift cable attachment. This strut being the last, there is only one cable instead of the two occurring where the inner struts are attached, other- wise the attachment is similar in principle to the usual (ierman practice. The spar box and strut and cable at- tachment is indicated in the detail sketch at C'. The tubu- lar compression strut is secured in the same manner as that of the fitting previously referred to. As previously pointed out, the trailing edge of the Alba- tros wings in in the form of a wire, and the method whereby the outer main rib is prevented from bending sideways is illustrated in the detail sketches at I) and I In addi- tion to the wire forming the trailing edge, there in another wire running parallel to it and carried right through the wings, the object of which appears to be to provide a counterpoise capacity. The wiring in the Albatros is not extensive, and in the case of the fuselage it is absent alto- . 2t_Tt wing Mellon of Ibt AllMlrol btplu*. 182 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Fig. ^5. The spar box and its attachment to the fuselage of the Albatros fighting biplane gether, and it therefore appears probable that the thin cables running along the wings and the longerons of the fuselage serve the purpose of providing the necessary amount of wiring, otherwise one is at a loss to account for their function. It has always been customary for German aeroplane designers to provide some easy means for quickly detach- ing the wings from the body, and the present Albatros is no exception from the rule in this respect. The cables themselves are not, it is true, fitted with the quick release devices one finds on the L.V.G., for instance, but the spar attachment has been designed to facilitate the removal of the wing, even if that of the cables has not. In Fig. 25 is shown the spar box and its attachment of the lower wing. A sheet steel box surrounds the root of the spar, and has in its end a slot into which fits the lug secured to the side of the body. Welded to the side of the spar box is a socket forming a bayonet joint, into which fits a pin fitted with a small spiral spring. The spar is held against the side of the body with the lug projecting into the spar box, and the pin is inserted and given a twist so as to bring the pro- jections on the pin into the notches in the bayonet joint, and the spar is secured. For removing the wing all that has to be done is to press the pin slightly against the action of the spiral spring, give it a twist and pull it out of its socket, and the spar can be withdrawn. The spar is secured to the spar box by screws, and the box is fur- ther secured against tensional loads by a steel strip about a foot long running along the face of the spar and an- chored at its other end by a bolt passing horizontally through the spar. As the lower wing spars are subject, in addition to the bending moment owing to the lateral load on them, to tension, the attachment to the body has to be such that it will resist a tensional load as well. Fig. 26. The wing flap and some wing details of the Albatros fighting biplane SINCI.K MOTORED AKU( )IM A \ I - IH.M The Inn to which the spar is attached tits into a recess in the h.ise plate formed by stamping. Tin- i\i-il pull is transmitted across tin luittiiin of the t'usi la^c via the brackets .-mil strips shown, which .-ire bolted to the base plat, holding the lug. In order to prevent tin- lug from tiirnini; it is riveted by four rivets as indicated. The upper planes are attached, as in nearly all (.er man iiiacliiin s. to a four-legged cabane. In addition to supporting the win^s the cahane of the Alhatros carries the radiator, wliirli is of the same shape as the wing siction and winch tits into an opening in the wing. The raliane is shown in Fig. -J7. It will he seen that one of the cahaiie legs carries for a short distance the water tube from tin radiator to the engine. The attachment of the upper wing spars to the e d. in. is somewhat similar to that of tilt- lower spars, inasmuch as a pin fitted with a spiral spring secures the spar to the raliane. Here, however, tin- similarity ceases. Instead of the spar lio\ into which tits the lug on tin- side of the body, the upper spars are provided with n forked lug, irohalily a forging machined to shape, of the form shown n l'ig. 28. Tin 1 lug of the opposite spar is of the same Impc. lint is. of course, reversed, so that when the two pars meet against the top of the cahane. their respective ar. staggered in relation to one another. From the mil attachment of the lugs it will lie seen that as hcv ar. staggered on the spar and in relation to one an- ithir. the spars will, when in plaee. come in line with lie another. On one of the outer faces of the forked iiiice is left solid, and is shaped to receive the onnded end of the op|(site lug. This has prohably been lone in order to reduce the shearing stress on the pin se- uriiiir tin- lugs to the cabane. The wing-Hap crank-lever of the lateral control is lori/ontal. as in so many other German machines. The untrol cahlcs for the wing-Haps are. therefore, arranged in vv hat unusual way. The details of this arrange- ire shown clearly in Fig. .SO. From the front and rear half of the wing-flap crank-lever cables pass down o pulleys enclosed in a casing mounted on the rear face if the hack spar of the lower plane. After passing over 'iilleys the control cables pass through the rear *pr to another pair of pulleys mounted on the tubular onipr. ssion strut, and hence to the controls in the body. \ light framework surrounds the pulleys as shown in the sketch, and forms the support for the hinged inspection v means of which the condition of the pulleys and rontrol cables may be examined. The tension of the P control cables in regulated by means of turn - inside the lower wing. These tiirnbnckles are situated close to the side of the body, and are rendered ihle by hinged aluminium inspection doors on the lower surface of the bottom wing. In order to pnv.nt the tnrnhiicklcs lr..m .-at.'hing against the . .1^. s of the wing rilis. cables and tiirnbnckles arc surround. , Fig. 29. The base plate to which the strut I'hr c.b.ne supporting the radiator ami upper plane Fig- * -Sketch showing lup on mot f upper main wing .par. >f the \llmtros biplane. Note the manner of carrying the water hrouph one of the culiane legs 184 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING socket is welded is of angle section, and is secured, via brackets as shown, to steel strips running across the body, and which take the tension of the lift cables. This ar- rangement is somewhat similar to that of the lower wing spar attachment, which we described in a recent issue. The lower ends of the two Vees are formed by short lengths of bent tube of slightly larger dimensions than the struts themselves, for which they form sockets. The details will be evident from the sketches and hardly need any explanation. Running across the undercarriage par- allel with the axle are: in front a compression tube, and behind a stranded cable. A steel strip protects the rubber shock absorbers from contact with the ground, and a padding of leather is in- terposed between the axle and the bottom of the Vee. The upward travel of the wheel axle is limited by a short loop of cable, against which the axle comes to rest after travelling the permissible amount. Side view of the Albatros C-V Fighter The chassis of the Albatros C-V Tvp SIN<;I.K MOTOKK1) AKK01M..\M> 185 THE FOKKER SINGLE-SEATER BIPLANE. Type D.7. SPAN CIKIkll TOP PLANE ., BOTTOM .. OVERALL LENGTH TAIL PLANE SPAN MEKiMT ... AIRSCREW GAP STAQQER ENOINE 4- r ,. i iir.. Mercedes 160 h p. 186 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Three views of the Fokker Single Seater The Fokker Single Seater Biplane Type D-7 This aeroplane presents features of very great inter- est, whether viewed from the standpoint of aerodynamic design or of actual construction. The machine which has been the subject of investigation was, unfortunately, rather extensively damaged, thus making absolute ac- curacy of description difficult, and trials of performance impossible. A similar machine, however, has been tested for per- formance by the French authorities, who have issued the following report: 1,000 2,000 3,000 4,000 5,000 Altitude metres (3,281 ft.) (6,563 ft.) (9,843 ft.) (13,124 ft.) (16,405 ft.) Time of climb 4 mins. 15 sees. 8 mins. 18 sees. 3 mins. 49 sees. ;2 mins. 48 sees. 38 mins. 5 sees. The principal dimenjfens are as follows: Span Chord (upper wing ) Chord (lower wing) Overall length Gap Area of upper wings (with ailerons) Speed at this height 116.6 m.p.h. 114.1 m.p.h. 109.7 m.p.h. 103.5 m.p.h. 94.9 m.p.h. 29 ft. 3 1/ 2 ins. 5 ft. 2 y 2 ins. 3 ft. Ily 4 ins. 22 ft. ll>/ 2 ins. 4 ft. 2 ins. . . . 140.7 sq. ft. Area of lower wings 78.3 sq. ft. Area of aileron (one only) 5.7 sq. ft. Area of balance of Aileron 5 sq. ft. Area of horizontal tail plane 21.1 sq. ft. Area of elevators 15.2 sq. ft. Area of balance of elevator l.l sq. ft. Area of fin 2.8 sq. ft. Area of rudder .5.9 sq. ft. Horizontal area of body 35.6 sq. ft. Vertical area of body 58.6 sq. ft. Area of plane between wheels 12.4 sq. ft. The following data regarding weights is taken from a French source : Weight of fuselage, complete with engine, etc 1. 3 -'.'. 2 Ibs. Weight of upper wing with ailerons 167.2 Ibs. Weight of lower wing 99.0 His. Weight of fin and rudder 6.6 Ibs. Weight of fixed tail plane 17.6 Ibs. Weight of elevators 9.9 Ibs. 1,622.5 Ibs. Wings As in the Fokker triplane, the extreme depth of wing section and the absence of external bracing are distinctive features. Both upper and lower wings are without di- hedral, and are in one piece. SINCiLK MOTOKKI) A KHOI'I .A M -s Sections of 111!' willL' -p.-ir of tl- l-'l 1)7 * 3. :. 4. Wing Construction In sharp contradistinction to the fuselage, which is con- st ructcd of stcrl even inclndim; members where wood is almost tmi\i rs.-illy used, the wings contain no metnl parts, if we exclude strut fittings and other extraneous features. There are no steel compression members, hut where the internal wiring lugs occur, special box-form compression ribs are fixed. The leading edge is of very thin three-ply, which has a deeply serrated edge, finish- ing on the main spar. The ribs are of three-ply, and are not lightened, although holes are, of course, cut where irv, to accommodate the control and bracing wires. A rib from the top center section, and one from the root of the lower wing, are both drawn to scale. See Fig. 1. The extreme thinness of the three-ply has given rise to a new method of fixing the flanges, on the ribs. In stead of grooved flanges tacked on so that the tacks run down the length of the three-ply, two half flanges of approximately square section are tacked together hori- ontally with the ply sandwiched between. Spars As may be seen from the various sections drawn to scale in Figs. 3 and 4, the spars are made up of fairly narrow flanges at top and bottom, joined on either side by thin three-ply webs. They arc placed approximately .So ems. apart. The flanges are made of Scots pine, and consist of two laminations. The three-ply has the two outer layers of birch and an inner ply which is probably birch also. The three-ply webs are tacked on to the flanges, and fabric is glued over the joint. The cement is an ordi- _'<-latine glue. The spar webs are glued to the flanges by a' waterproof casein cement, which is proved to contain gelatine, while the plywood adhesive also a casein cement is water- proofed and of sufficiently good quality to withstand four hours' immersion in boiling water. The trailing edge is of wire, and tape crosses from tin- top of one rib to the bottom of the next in the usual way. This tape lattice occurs about half-war between the trail- ing edge and the rear spar. Fig. 3 shows the sections of the front and rear upper plane spars, taken in the centre section and at the inter- plane struts, while Fig. 4 gives the corresponding lower spar sections. The ribs are stiffened between the spars by vertical pieces of wood of triangular .section. There arc two such pieces on each rib in the upper plane, and one in the lower plane. All the woodwork of the wings is varnished, and fabric is bound round the flanges of the ribs and glued to the top and bottom of the spars. The workmanship is decidedly good, and the finish neat and careful. Struts The struts are all of steel tubing of streamline section, and the centre section system is particularly worthy of attention. All those three struts which meet at a point on the front spar of the upper wing are welded to the fuselage framework, and arc thus not removable when the machine is dismantled (see Fig. 5). The strut which joins the rear upper spar to the front lower spar, how- ever, is not welded but is fastened by a ball and socket joint, which is the subject of Fig. 6. It will be noticed that the ball forms the extremity of n threaded bolt which is screwed into the end of the strut, thus making it ]>- sible to adjust the length of the latter. Both ball and socket are drilled and a bolt locked through the hole. The attachment of up|>er centre section struts to the wing spar is shown in Fig. 1. As is made clear in the scale drawings, the interplane struts are of X shape when seen from the starboard wing 188 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Fig. 5- Fig. e. Hi. . fig. 7. Fig. 8, Fig. 10. Fig. 12 KEY SWITCH PRESSURE CAUSES GREASE PUMP ACHTUNG; Hohengas* FROM AUXILIARY TANK jV ^^ CAUTION ,HI6H ALT. THROTTLE CONTROL AIR RELEASE COCK PUMP OFF PUMP .MOTOR PUMP TO'flUXILHRYY? TAM K Fig. 17 Pig. IS. Fig. 16 SINCJ.K MOTOKK1) A KKUIM.A \ I .s IH'.t tip. Till- tlircr mrlnllcrs of tin \ are w el, led together, and all four In-c extremities li;i\r tlir :uljiist:ili|i- attach inciit descrilN il abmr. It lias alrrailx IIIVM in. -iitinrii (I that tlnTf IN \tern.al hracing. tin win^ , ^instruction -ill^' in id.- surticicntlx strong against hit stresses |,, ohxiite its necessity, anil tin form of tin- mtcrplnnc struts is intcrestin:,' in this i-nnni-i-tiiiii. Fuselage This is exactly similar in design ami construction In tin- triplanc 1 o{ course, fur tin- difference in type of engine ami for tin- fart tli.it Ixith wings h.axe twn spars instead of one. Tin longerons and cross struts arc .it circular si-rtioii sli-rl tube wrlilril in plarr. and carrying it the corner tin small c|iiadrant of strrl tube wliirli cnrrirs tin- bracing. Tin- diameters of these tubes vary I rom M Minis, to IS nuns., and tin- strrl was of -2 \ gauge in tin- plans where tin- tnlirs had lirrn pirrrrd by bullets. This hr.-irini; wi II repays attention. All sides of ,-ach section an- cross liracrd with piano win-, which is simplx passed round tin two lugs to l- joined ami has its rv trnnities connected In means of a tnriiluicklr. This nirthod has tlir great advantage that only two loops are nired in tin- wire instead of four, and in consequence this bracing can lie very rapidly assembled. It is also possiHy lighter in relation to its strength than the usual amusement of single wire bracing. Fig. 8 shows how a handle is clipped on to the lower longerons. The front part of the body is a particularly good piece of welding, and includes the engine and radiator sup- ports a> well as the arrangement by which the continuous spar-, of the lower planes can be placed in position. This is dom by removing two fork-ended tubes (one each side if the body), and replacing these when the wings are in position. I i:,'. <> shows how the wing spar is joined to the fuselage and Fig. K) shows the fuselage joint at this point. Tin- cowling is of aluminum, and covers the front por- tion of the fuselage on all four sides. It is extended on the top to the cockpit, and underneath to beyond tin- rear spar. The cowls are arranged in convenient sheets, and an t istem-d by means of bolts and nuts of unusual The nuts ha\e small handles about 1 in. long, which enable on.- to manipulate them without tools. From . r half of the cockpit to the junction of the tail and Ixtdy. the top is furnished with a three-ply fairing, which xtends oxer not quite the whole width of the fuselage. This is shown in Fig. 1 1. Tail I In tixeci tail planes and elevators are almost similar to those of the triplane. i.e., the tail is triangular and the rs balaiierd and divided, although they are actually n one piece. The biplane, however, has a tri- angular Hn whose foremost point is fixed an inch or two to tin port sale of the centre line of the machine, thus proxiding a surface which is inclined slightly to the longi- udin-il axis of the aeroplane. This is illustrated in Fig. s is no doubt arranged to balance the tendency of '> machine to turn to the left in flight, due to the slip- in. I In framework of the tail is of circular section steel throughout, including the trailing edges, and this frnnn work is arranged to give the ti\ed tail symmetrical i tmbcr. The attachment of the tail plane to tin fuselage U simple and etl'r. In \ -, m t| lr trip! the top longeron-, arc dropped at this p.. ml sutlicnntly to allow the tail plain to haxe its top surface Nxi I with the top of the fuselage, and lime bolts passing through the main steel tube of the tail ami through short piece* ot tube welded to the |MI<|\ framework secure It il, this ' f the three l>olts, one is plan . I il nlliir side of the top of the fuselage on the front of the tail, ami one at tin end of tin body framework. Tin tail pi nn i at a slight angle of incidence about ML. dcgr. , s which is not intended to IK- adjustable, but which could easily lie altered by nn alls of a few washers ami longer (Milts. The tail is stay, (I by two streamline section steel struts, which connect tin rear lulu- of tin tail plane with the lottom of the sternpost. as is shown by the general arrangement drawings. These struts an not harlteil. 1'rom the sketch of the tail skid (Fig. 1M), it will be i that this member is balanced at a point al>oiit one third of its length from its lower end. and that the slnx-k absorbing arrangement consists of two helical stec I springs. Undercarriage This is a feature of the machine which carries a distinct trace of British influence. The angle between the two limbs of the Vee is usually, in German aeroplanes, very obtuse; i.e., the two top points of attachment are widely- separated, while British practice leans towards making this angle fairly acute. In the Fokker the angle be- tween the struts is about 53 degrees. The section of the steel struts is streamlike in form, with major and minor axes of 65 mms. and 3-1 mms. respectively. The metal is SO gauge. The upper attachments of the undercarriage struts are of the ball and socket type, with a bolt through, similar to the interplane strut illustrated above. The junction of the lower extremities and the slot which allows for axle travel is clearly explained by Fig. I ^. The bracing cables, which connect the upper extremities of the front struts with the opposite lower ends, are attached in the usual manner to lugs welded on to the struts. It in inter- esting to note that in the crash which wrecked the ma- chine, one of these lugs has torn out a small piece of tin sheet steel of which the strut is formed, though there is no sign of fracture at the weld. The least usual characteristic of the landing carriage, however, is the provision of a small cambered plane sur- rounding the axle, just as is the case in the Fokker tri- plane. This auxiliary plane has been badly battered, and few details are available, but the sheet aluminium box which surrounds the axle remains. This box is rectangu- lar in section, and the edges arc riveted together on the upper side. It forms the main and only spar of the plane. the construction of which is \er\ similar to that of the main plane. Tin- shock ahsorlx-rs are of the coil spring type, and are wrapped in the manner illustrated in Fig. lY The wheels are 760 X 100. Engine and Mounting The engine is a Mercedes of 1HO h.p. A full report on this type of engine has already been issued, but the pres- ent example possesses one or two minor points of differ- ence from the standard. The chief of these is the fact 190 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING that this engine has domed pistons, giving higher com- pression. As has already been mentioned, the engine bearers are steel tubes, supported on a steel tubular structure welded up integrally with the fuselage frame and with the centre section struts. The diameter of these two parallel tubes is 34 mms. and the gauge 14. Each tube carries four " pads " of the type shown in Fig. 15, to which the crank- case is bolted. Radiator The radiator, as may be gathered from the scale draw- ings and sketches, is of the car type (another departure from modern German design), and is supported by steel tubes which are part of a fuselage frame. The radiating surface is surmounted by a curved fairing, of which the port-side half is a brass water tank, into which the filler leads, while the starboard side is merely an aluminum fairing. The radiator is constructed of brass tubes ar- ranged parallel to the engine crankshaft. The tubes are circular in section, but expanded into hexagons at either end and sweated up there. Each hexagon measures 7 mms. across the flats. The single shutter, as will be seen on reference to Fig. 16, is normally held open by a spring, but can be closed at will by pulling a small cable. This shutter even when completely closed only puts out of action a small por- tion (roughly about one-third) of the cooling surface. Petrol and Oil Systems There is only one fuel and oil tank in the machine. It is of sheet brass and is slung from cross tubes clipped on to the top longerons, just in front of the ammunition magazines, which are placed immediately in front of the pilot. So far as can be ascertained from such external evi- dence as is afforded by fillers, piping, the lines of rivets on the tank, and the gauges and petrol cocks, it may be said that this tank is divided into two petrol tanks and one oil tank. The main petrol tank has a capacity for 61 litres .(approximately 1 sy 2 .gallons), and is provided with a baffle plate. The reserve tank holds 33 litres (ap- proximately 7*4 gallons), while the oil tank carries' 4% gallons. From the brass disc which is sweated to each flank of the tank, it would appear that a tie rod passes across the tank from side to side. Both petrol tanks work under pressure, obtained initially by hand-pump, and main- tained by the usual mechanical air-pump. The dashboard carries, besides the main switches and a starting magneto, a two-way cock which allows the pilot to use petrol from the main or auxiliary tank, or to shut it off completely. A separate pressure gauge for each tank and two two- way air pressure cocks are also mounted. Throttle Control A sketch of the throttle lever, situated on the pilot's left, is given (Fig. 18). This lever actuates the car- buretor throttle by the means shown. The compression tube between the quadrant and the balanced lever is over four feet long and about five-eighths inch in diameter. Although heavy-looking, this control is, of course, made of very light gauge material. The adjustment provided at the pilot's end of the control should be noticed. The control works in conjunction with a Bowden type lever on the control lever, as shown by Fig. 19. The twin cables from this auxiliary throttle lever are attached to the main throttle control Fig. 18 shows the attach- ments. Controls The control lever of the machine works on precisely the same system as that of the triplane, but the grip at the head of the column is quite different. Reference to Fig. 19 will show that the usual two-handed grip is replaced by a single handle for the right hand. " The left hand is free to manipulate the auxiliary throt- tle control, inter-connected with the main throttle lever. It should also be noticed that the usual pushes for firing guns are absent, and the interrupter gear is actuated by pulling either or both of the levers by the fingers, while the thumb rests on the specially arranged place. There is no separate arrangement for firing both guns together, and it is not possible to lock the elevator controls in any given position. The longitudinal rocking shaft carries at its front end two arms to which the aileron control cables are fixed (see Fig. 20). These wires cross; and pass upwards and out- wards to aluminium pulleys on ball bearings, which are attached in pairs to a hinged sheet steel framework. Or the way these cables pass through short tubular guides fixed to the top longerons. The aileron levers follow con- temporary British practice, and project vertically above and below the plane. The elevator control wires are taken direct from the control lever, one pair above and one below the fulcrum The rudder bar (see Fig. 21) is of neat and light weldec construction. There is no adjustment to allow for varia- tion in leg-length of different pilots, but it should be no- ticed that the pilot's seat is adjustable as regards height The means by which this movement is obtained is exactb Fig. 19. Control details of the Fokker D-7 SINtil.K MOTOKK1) AKUOl'l \\|> 1JH In same as the arrangement in tin- triplanc. i.e., the seat > a sheet aluminium liuckt I uilh .1 three ply bottom sup lorted by a framework ol st.,1 tubes which grips the _re cross struts In fnur clips, which c.-in In- placed it any height. '1'his i-. in.-iilc clear by 1 'i^. Fabric and Dope The f.-ihrie is nut attached in any w:iy In the longerons, nit is simply carried oxer tin- fuselage and laced ahnii: he bottom centr.-il line. There is .1 cross-piece of fabric aced to the cross tubes immediately behind the cockpit. The fabric is coarse flax, coarser and less highly eal- ndered than the type usually met with, and a good deal leavier. It is colour printed in the usual irregular polygons. The bright red paint, mentioned below, is removable by ilcohol, but not soluble in it, coming off ns a skin under reatment. I'nder the paint is a dope layer an acetyl cellulose. Siit In r paint nor dope presents unusual features. Wrights I'. lint !).'.() (fins. |MT s<|. m. Dopr (iM.l (fins. JUT s(|. in. I al.ric I i:Ui (rins. |-r scj. m. mr.{.7 |rms. per sq. m. SI ri-n jtth 1779 k in. Kxtriisinii 7.0 jx-r cent. \Vhere the wiiiys are not painted, the fabric is covered vith a linn layer of dope only. Schedule of Principal Weights Ib*. oc. I |'|MT wiii(f, fiiinpletr with .nl. r,, u-. jiiillrys brwinp irr>. falirir and strut litlinjfs ! \M 1 OMIT win); (mi ailerons titled), complete uilh strut littiii|r< and falin- - 97 N I rut IH-IUIVII winj-s | > Str.ii^'lit strut. U-twiiii fiis,-|.i L . r and trHilliifr spur of upper winy * 8 \ilenill Ir.iin.-, with hilife flijls, witlioilt f.iliri. 4 8 It udder frame, with \\ii\fr clips, witlxinl fnlirir 4 II I in fr; . M ithric 1 14 Tail planes (eninplet. 111 .me plrcr), without fabric... li 6 I kvntors (complete In one piece), without fnhrlc II 9 It.iiii itur einptx l> I 'ndrrcarriafre strut, each 2 10 riulrrcarrUfre \lr, with shock itltsorlirr lioblilnk 1H 8 Uol.liin. each " : Sh 4 Aluminum tuhe. forming rear spar of undercarriage plane 1 8 Wheel, without tire and tube II 8 Tire and tube 9 4 Tail strut I 13 Fabric, per square foot, with diijw 1 Bottom plane compression rib 15 Itottom plane ordinary rib U II Top plane ordinary rib. at centre of plane 1 Bracket, with holts, attaching top plane to fuselage struts 1 II Main spar, top plane, including fillet for ribs, per foot run in centre 1 11 Owing to tapering ends the average weight per foot of the spars will be slightly less than this figure. The Tarrant " Tabor " Triplane Tarrant "Tabor." equipped with six \apier "I. ion" rnvines of .VN h.p. each. Spnn of tin- middle plane is 1:11 ft. : in. Overall height is :7 ft. : in. Overall length. 7:1 ft. .' in. Total weight. 45,000 pounds 192 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Gunners Sea Pilots Seat. HALBERSTADT GENERAL DETAILS Two-Sealer Biplane Span 35' 3}' Gap 4'0'to3'8J' Chord Top Plane 5' 3i' Chord Bottom Plane Overall Length Tail Plane Span Height Engine Set Back of Planes Propeller 9' o' Track 6' 4' Stagger 2' o' 4" 3J- . 24' 0* . 8' 11* 9' 6' . 160 h.p. 4 PLAN DRAWINGS OF THE HALBERSTADT FIGHTER The Halberstadt Fighter This German machine is a two-seater fighter. General Details Bristol Technical Department has stated that the Hal- berstadt represents, in all probability, the high-water mark of two-seater Germa.i aeroplane construction, as it is not only well and strongly constructed, but its general behaviour in the air is good according to modern fighting standards. Span of upper plane 35 ft. 3\iil .mil 1 inovHlilr Militant hud en t.-xt . I. His. l l'l"' r wi "(f. -iiinp|rlr uith .ol.r .iili-r.iti r(Ml. ilmg io.ul on tot '..,.' II.- ''-' ""' ' >lrut attachments, hut without lid liruriiiir wirrs ,n,l tabfi . / Performance I "-T iiic. .1* .il>m.- < no aileron nttrd) . a - \ilrnm ( r.p.m. \ili-rnn Imr, wilh flnnp- It,., otrii.nl, Indicated |"|"I'|H- *ru. '-,.. .,i| H ,,,t Mi.,. inf.. nun. Airspeed .'"7 '" ; tr " '"*'"' '"'; : ' Cli.,.1, to .'..I" N. ft. llu N "'I' 1 ''''-' ttlth '""I'T ,Ml itr.vlty rii.,,1. I ,000ft MO -,l .<-...( r.,1 ,. rank .n,M-rcln K wirrx .101 CUmb to 14000 fl ,1 53 BO H-" l'l |-lm- (rrh). with fJ,rk . T 8 Rodder, complete iih fhri<- .78 , Kli-vatdr. coinplrtr, with Mngr dipt and faltrtr I ' Serrto .,-.l.,. K (lu-.^ht at wind, ,-l.mb is 100 feet ,HT Hni ,,,,,,..; wi ,' h f ., irlc , 13,500 ft. ,irr M-rtion >trul . .97 aliMiliitr i-riliiii;, Ili.OOO ft. Straijrtit orntrr x-i-tinti slrul 3 i^ (.r, .it.xt hci.nlit r.adi.d. U.SOd ft. in IU ininiit. -, K> rnilrrrarrla((r. rcmiplrtr wilh >trut and l.r.rin K , . ( j s whrrN, tyrr-, mill shock aliMirlirrs I0i Sliix-k hvirl>rr (innltipli- mil priii)r t\pr).rarh .... 4 Stability and Controllability Z!**L? *""*'" *"'"'"" **** \\ ncrl, w ii n IV FT . o 4 Hat, of ,.,,, a, IU. height, , f,,t ,,, r .inute. 31^-5 ^^S- ^ " !u> ina.-liMir caim..) be considered vteble. There is WinKS . trailing .,,,, r . ,HT foot run o 14% a tendency to stall with thr mjiine on, and to dive with tin- , iinin. ,,tl. Din .-tionallv. owing to tin- propeller Historical Note s,rl. thr ,,,;,,.|,i,,,. swings to the left, but with thr ni,{iiii- The pr.-s.-nt H.-,ll.,-rst,,lt fightrr is .-, e ash was 'M.-.nralMlity is K O,H|. and this fraturc. tak.-n in lls ,.,| ,,, f, ir l v | nr)f< . ,. x t,., lt . U.th in the fuselage and njmu-ti,,,, with th.- exceptionally tin,- vi.-w ..f thr pilot will>INi f)llt in j| 1( . m ,, r( . ln , M j,. rn ( |,. s ^ n ,p riu .,. is ( . xo i u . bterra an,! thr h'.-hl of fire of the latter, makes thr siv ,.|v ...L.pted. Thr r.-.-ir spar was of thr ordinary ' irhin, oti,- to ! r.-.-konrd with as a " two s, at, r fighter." (ion type without three-ply rrinforerment. Thr fuselage. ^h the climb and speed performances are poor ,,f somewhat similar shapr, was fabri, ,,,v- r,d. Balanced Hpd by ..-ntrmporary British standards. elexators and rudder were fitted, but no fixed tail plane or fin. Tli, arrangement of the centre section, with tank rincipal Points of the Design and radilllor> w;ls M1 | 1 , l . 1Iltia l| v . s m ,.. |, 011 |,i,. h.^, - _lr bay arrangements of wings. of interplanr struts were adopted, but thr struts tin m iiieuoiis set back of thr main planes. sdves were of the welded-up ta|-red pattern. The ailer- Bmpennage fre>- from wir,v ons were controlled by wires and not. as in the prrvnt I 'iisilage ta|MTs to a horizontal line at the rear in di- example, positm-ly. Both planes had the same chord and utradistinetion to the usual (,, rinin practice. the upper wings had an overhang. The weight of the Pilot's and observer's cock-pits constructed as one. complete machine without pilot was 17*8 Ibs. \ / i; _..,,_,,-..._.,--,. AUSTRIAN TYPE ALBATR05 HAN5A BRANDENBURG ^00 H-P FIGHTING TRACTOR MILLIMETERS ItOO tOOO I Mclaughlin 194 SINC.I.K MOTOK1.I) AEROPLANES The German Hansa-Brandenburg Tractor Tin- struts st.-iiifjercd outward at their lower rnd-. is a ttatiirc peculiar to this machine. Many of tin- Albatros features art 1 sci n in this machine, together with a mini lx-r i>f original and unique fittings. Tin- accompanying drawing-, show a side and front vii-w and a plan vn from In-low . General Dimensions Sp.m, ii|i|irr plane l-.i40 nun. Span, low IT plain- II. 7 .'n nun. Cliortl. I .illi planes l,7i:l nun. Area, iipprr plain- ^."70 M). ini-lrr-.. Area, lower plain- 1,790 v|. meters. (l.ip lu-twt-cii planes 1,7 l:i nun. (Kcrall hcicht ..I I 'nun. Overall length 8,370 mm. M,.t..r. \V.ir-k:ilowski **> h.p. Planes Plain-, arc in four sections two upper and two lower. l'|i|n-r pi. me M -etions joined at tin- top of a cabane formed of steel tube :io liy Hi mm., with lower ends terminating in fittings attarln-d to tin- upper longerons of the fuselage. F.ach upper plane section has an area of 1135 sq. meters. F.ach lower plane section has an area of 895 sq. meters. Ailerons are attached to subsidiary steel tube spars to the rear of the main wing beams. Attachment is made with a fitting of sheet metal and soft wood blocks, with tiler to take up the wear. Kach aileron has five such hinges. Ailerons each 2850 mm. long. Wing beams arc cut in two vertically, hollowed for light- ness and mortised together with hardwood strips. For- ward .spar varies from 70 to 72 mm. in height and the rear spar the opposite; both are 85 mm. thick. Filtering edge is curved to a diameter of Ml mm. Front spar centered 100 mm. from leading edge. Wing spars SIMI mm. apart. Halt. us are ->.:> thick and 13 mm. wide. Webs 45 mm. thick, cut away for lightness to within 15 mm. of the battens. Light veneer strips. 12 mm. wide, reinforce the weds between lightening holes. The interplane struts are of 32 mm. diameter steel tube with their ends terminating in eyes for attachment to the strut sockets. Hollow wood fairing strips are bound to tin- rear of the strut tubing, giving it a streamline form. and bringing its width to 126 mm. Each end is attached by an s mm. bolt. Lift, landing and incidence cables vary from 5 to 7 mm. in diameter. Fuselage Overall width of fuselage, 1020 mm. From the for- ward engine plate to the rudder, the fuselage is 7180 mm. long. A formed cap fits over the forward engine plate, and the propeller shaft goes through it. Four sheet metal engine plates carry the two 50 by 100 mm. engine bed rails. The longerons are solid, 80 by 45 mm. at the front, the lower pair tapering to 19 mm. square and the upper pair 17 mm. square. The pilot's seat is set in a recess formed at the top of the main fuel tank. Overall dimensions of the tank top 300 by 820 mm. ; bottom "OO by 82(1 mm. ; height 650 mm. The back forms a right angle with the top and liottoin and the forward end slopes down from the top. A recess 1711 nun. .|,.|.. 71111 .mn. long and t?(l mm. w nit- is proxided for the seat. Seat :>.MI mm. long and UO mm. wide, rcsimg on n pair of iron bands ~ :. mm. thick and 31 mm. wide, which encircle the tank. A tilling tulx- runs up at the rear of the tank, mar the .side, with n :> I nun. opening. A fixed machine gun is provided for the pilot, located on the upper plane. The ^miner's cockpit, at the rear, is provided with a movable machine gun clamped to a rail around the cockpit o|x-ning. Tail Group Tin- horizontal stabilizer is in one piece, resting on the upper longerons. The forward end is rounded off at a HIM mm. radius. Overall dimensions, 229(1 by .'!> M) mm. Surface at each side of body, 192 square meters. Tin- edges are of steel tube 20 mm. in diameter and the in- ternal structure is of 10 mm. diameter tulx-. It is sup- ported from IM-IHW l>y a pair of steel tubes of 25 by 13.5 mm. section. Threaded eyes in the lower ends allow of their adjustment. Lower ends attach to lower longerons at a point 1860 mm. from the fuselage termination. Slots. GOO mm. apart, are provided where the flap con- trol cables run through the stabilizer. From tip to tip the elevator flaps measures 3500 mm. Maximum width, 670 mm. Kach flap has an area of 83 square meters. Edges are formed of 15 mm. tube, and outer tips curved to a 120 mm. radius. Flap hinges are of sheet metal, soldered to the 25 mm. till" of the flap and stabilizer. Fiber blocks between the tubes space them 10 mm. apart, and take the friction of the flap movement. The vertical fin is triangular, 700 mm. high and 13OO mm. wide. The rudder is l<>'>(> in overall height. Width at rear of pivot, 670 and width forward of pivot (the balanced portion) 340 mm. Forward edges curved to a 30 mm. radius, and trailing end to a 110 mm. radius. Two hinges attach the rudder to the fin. The control lever is of solid steel, and it spaces the control wires 117 mm. apart. Landing Gear The axle is of steel tube, 54 mm. outside diameter. Mi mm. inside, located at a point 1680 mm. from the front of propeller hub. Landing wheels are 770 mm. in diam- eter by KM) mm. wide, and centered 2070 mm. apart. Two sections of streamline fairing are bound to the axle, and a claw brake between them. The brake is 730 mm. long; 230 mm. forward of the axle and 5OO mm. to the rear. The claw is 145 mm. in length, and the brake is operated by a cord from the pilot's seat. The chassis struts are of 70 by 35 mm. tube. The for- ward pair is faired with streamlining to a total depth of 120 mm. A peg is located half way up both of these struts as a means of mounting to reach the motor. At the lower end of chassis struts, the shock absorbing elastic cords are bound. Grooves keep them in place and a leather strap, strung from forward to rear struU, limits the upward movement of the axle. Details of the Hansa-Brandenburg Tractor 196 SI\(.I.K MUTOKKI) AKKOl'I.AM - 197 Details of the Austrian Hansa-Brandenburg Tractor '< One of the i lrv.il, ir rontrol levers Rear attachment of tin- tnil plain- to (lie fuselage Tin- tn fnrwar t' i't 1 liU'Hji 1 VH The Wittemann-Lewis Commercial Biplane The Wittemann-Lewis Aircraft Company Model " F. A. 2 " is the result of careful planning for a commercial airplane by the Messrs. Wittemann, and built to the design of A. F. Arcier, A. F. R. Ae. S., formerly chief engineer of Handley-Page, Ltd., and now chief engineer of this Company. The principal features of the machine are the unusually low landing speed, the large capacity and sumptuousness of the body, and the comparatively small space in which it may be housed by folding the wings. Wings: The upper wings are composed of three sec- tions, the lower ones of four. The outer sections hinge back by simply removing four pins, when in the folded position they clamp back against the fuselage. The spars are I section spruce and the ribs special built up. The interplane struts are spruce. The main spar clips are so designed that they set up no additional bending mo- ments. Body: The L. C. Liberty motor is silenced and is mounted on ash beams supported by tubular construc- tion. The whole power unit comprising: Propeller, Radiator, Motor and Tanks, is removable in one unit by undoing six bolts and disconnecting the control and instru- ment leads. Risk of fire is reduced to minimum by fire- proof bulkheads and by suitable placing of carburetors in fireproof compartments. Reliability of the motor is assured by reducing its maxi- mum output and by gravity fuel feed. The cabin is approximately 5' 6" x 4' x 9', giving 170 cu. ft. of unobstructed space, and has seating capacity for four passengers comfortable swivel arm chairs and a folding table are provided. The exhaust heating and the ventilation can be adjusted by the occupants. The en- trance to the cabin is large and within stepping height of the ground, making the machine as easy to enter as the average automobile. Pilot has unobstructed view and is seated aft of the main loads. Landing Gear: The landing gear has an exceptionally wide track, making overturning impossible, long travel shock absorbers are fitted and a dashpot provided to pre- vent rebound. These precautions together with the low landing speed make the machine very safe and easy to land. The tail skid is steerable on the ground to facilitate ground manoeuvring. Controls: A " Dep " arch is provided, and the rudder is operated by foot pedals. The tail is adjustable in flight for varying loads. The disposition and size of the controlling surfaces are such as to assure a large degree of inherent stability. Area: Top plane, 3S3 sq. ft.; lower plane, 306 sq. ft.; ailerons, 92 sq. ft. ; tail plane, 70 sq. ft. ; tail flaps, 20 sq. ft.; rudder, 12 J /6 sq. ft.; fin, 8 sq. ft.; chord both planes, 6 ft. 9 in.; gap, 6 ft. in.; span, wings extended, 52 ft. in.; wings folded, 22 ft. 6 in.; o. a. length, 35 ft. 1 in.; o. a. height, wings extended, 11 ft. in. ; o. a. height, wings folded, 9 ft. 9 in.; weight full, 4,040 Ibs. ; useful load, 1,650 Ibs; loading 6.33 Ibs. per sq. ft.; duration (cruising), 4'/ hours; landing speed, 35 m.p.h. ; top speed, 105 m.p.h.; ceiling, 15,000 ft.; climb, 10,000 ft. in 30 min. ROLAND D.n. 16O H.P MERCEDES. I : 1cK- wop " The Kolml Sin^k--.tcr Ch^er D.ll. PUn, W<- .nd front elethm. to 11)0 200 TKXTBOOK OF APPLIED AERONAUTIC ENGINEERING Starboard quarter view of the lioland D.II. chaser The Roland Chaser D. II. The dimensions of the Roland D. II are very small: Span of upper plane 8.90 m. Span of lower plane 8.50 m. 1 .ength overall 6.95 m. Height 2.95 m. Its weight 827 kilogs. with full tanks is slightly greater than that of the Albatros D.III chaser. The lift- ing surface being 23 sq. m., the wing loading is 36 kg./sq. m. (7.2 Ibs./sq. ft). Fuselage The construction of the fuselage, and its peculiar shape, merit special attention. Being built entirely of three-ply wood and covered with fabric, it is of the monocoque type, of oval section, and terminates at the stern in a vertical knife edge. The construction is excessively light, the framework consisting of very thin longerons running through the whole length of the body, the curves of which they follow. Rigidity is only provided bv the ply wood, made in two halves joined along the middle of the top and bottom. The total thickness of the six layers is only 1.5 mm. From the pilot's seat to the tail there are only four formers of very small thickness. Between the pilot's seat and the motor the fuselage forms a projection tapering upwards to form at its upper extremity an edge 0.11 m. wide, to which are attached the radiator and the top plane. The top plane is cut away to accommodate the radiator. This arrangement of an upward projection of the body itself takes the place of the cabane. On the lower part of fuselage, and built integrally with it, there are the rotts to which the two halves of the lower plane are attached. At the rear the tail skid, of wood with a shoe of metal, pierces the fuse- lage, and is supported on a projection of ply wood similar to that employed on the Xieuport. The pilot is placed very high, and has in front of him two wind screens, one on each side of the central struc- ture carrying the upper plane. Planes The planes are of trapezoidal plan form, of unequal span, without stagger and dihedral angle, but with a sweep- back of 1.5. The chord, which is uniform, is 1.45 m. and the gap 1.3-1 m. The ribs are at right angles to the leading edge. As the inter-plane struts are secured to the spars over the same rib, it follows that in the front view the struts do not come quite in line. The spars of the upper plane, which are of spruce, are spaced 0.83 m. apart, the front spar being 0.13 m. from the leading edge. The ribs, of which there are 12, are of I section with flanges of ash. They are spaced about 0.37 m. apart. In the middle of each interval there is a false rib running from the leading edge to the rear spar. In each wing there are four compression members in the form of steel tubes 25 mm. diameter. These tubes are evenly spaced, the distance between them being 1 .30 m., and are braced by 3 mm. piano wire. Between the front spar and the leading edge there are two tapes running parallel to the spars and crossing alternately over and under consecutive ribs. Two more tapes are similarly arranged between the spars. Certain corners are stiffened by reinforcement by ply wood. Each of the upper planes carries an aileron, which is not balanced and of equal chord throughout. A strip of three-ply wood, under the fabric, covers and pro- tects the hinge fixed on the rear spar. The aileron meas- ures 1.82 m. in length and has a chord of 0.42 m. Its leading edge is a steel tube of 30 mm. diameter. The aileron cranks are operated, as in the Nieuport, by two vertical tubes. In the left top plane is mounted a petrol service tank. The lower planes are constructed in much the same manner as the top ones. The spars are similarly arranged and are consequently the same distance apart. In each wing there are 10 ribs, of which nine measure 0.01 m. and the last one 0.025 m. Between the ribs are false ribs measuring 10 mm. The internal wing bracing is the same as that of the top plane, but the distribution of the four steel tube compression struts (of which one is 20 mm. and the other 25 mm.) is somewhat different. From the first to the second is 1.17 m., from the second to the third is 1.13 m., and from the third to the fourth 1.11 m. The lower planes are attached to wind roots built in- tegrally with the fuselage. The angle of incidence is 4 at the second rib and 3 at the seventh. The interplane struts are in the form of steel tubes 0.025 m. diameter, stream-lined with a wood fairing which brings their depth to 0.09 m. The Tail The shape of the tail can be seen from the plan view of the machine. The fixed tail plane is built of wood, while the two elevator flaps are constructed entirely in metal. A note should be made of the attachment of the tail plane to the body. The leading edge of the tail plane is SINCl.K MOTOHI.I) AKUOl'I.ANK.s -in II. II..I...:! D.I I. ,.|r,s,. r . (1) of "bump" supporting top plnnr nml radiator. (.') e l>olt for HttH.liinif main planes. (3) I'pprr plane. (4) One of the miiln plane rllw hollowed out. and into the hollow space thus formed fits n piece of wood which runs across the fuselage and the ends of which project (1.50 m. on each side. Further rigidity is uivm to tin structure by two stream-line tubes runnitifj from the tail plane to the rudder hinge on the I fin. The rudder, which is roughly rectangular with round, (1 corners and has a forward projection for l''il.-incing. is built up of steel tubes, while the fin. which is made integral with the body is of three-ply wood. Engine The engine fitted on the Roland D. II is a 160 h.p. (lea six-cylinder vertical engine. The exhaust col- Irctor is nearly horizontal, and is placed on the starboard side. In addition to the gravity tank in the top plane there is a main gasoline tank measuring 70x70x25 un- der the rudder bar. The airscrew has its boss enclosed in the usual " spinner." Undercarriage The undercarriage is formed by two pairs of Vee struts, braced diagonally by two crossed cables. Their attach- ment to the fuselage occurs at two sloping formers. The axle, which is placed between two cross tubes, is enclosed in a stream-line casing. The track is 1 .7.1 m. The wheels measure 700 by 100. The shock absorbers arc of rubber. Siile view of the fusehjre of the Roland IHI rli.'isi-r. Tl mil siw of this 111:11 -liinr is apparent from the picture. 20-2 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Comparative specifications of the L. V. G. biplanes C.II., C.IV., C.V., and Rumpler C.IV.: L.V.G. Rumpler Span (upper wing) Span (lower wing) Total length Height C.II. 12.85m. 11.35m. 8.10m. 3m C.IV. 13.60m. 13m. 8.60m. 3.10m. C.V. 13.62m. 13.85m. 8.10m. 3.90m. C.IV. 12.60m. 12.10m. 8.4m. 3.25m. Lifting surface . . Weight 37.60sqm. 845kg. 40sqm. 900k g. 42.70sqm. 930kg. 33.50sqm. 1,010kg. Power of motor . . Make of motor . . . 175h.p. Mercedes 235h.p. Mercedes 225h.p. Benz 260h.p. 250h.p. Mercedes or Maybach Note 1 metre = 32.37 inches. 1 sq. metre = 10.75 sq. feet. 1 kilogramme = 2.2 Ibs. The L.V.G. type C.V. is a two seater. It belongs to the " general purpose " class. Less speedy on the flat than the Rumpler C.IV., its rate of climb is inferior (4000 metres in 35 minutes), and equally its ceiling is less elevated (a little more than 5000 metres). Its speeds are as follows : At 2,000 metres 164 km. per hr. At 3,000 metres 160 km. per hr. At 4,000 metres 150 km. per hr. The Wings The upper and lower wings are set at a dihedral angle, more so the lower ones. This dihedral is of 1 to the upper wings and of 2 to the lower. They are neither staggered nor swept back. Front view of the L.V.G. biplane: type C.V. The L. V. G. Biplane Type C. V. The trailing edges of the wings are flexible. The ribs are spaced about .4 m. apart, with false intermediary ribs. The incidence of the wings is as follows: At 1st and 2nd ribs 4.5 At 3rd to 9th ribs 5 At 10th rib 4.75 At llth rib -I -5 At 12th rib 4 At 13th rib 3 The upper wings, viewed in plan, are slightly trape- zoidal, with rounded edges. Their chord is 1.74 m., and in the centre a semi-circular piece is cut out of the trailing edge above the pilot's head. The ailerons project past the ends of the wings by .84 m. Their form is rounded, and resembles that of the ailerons of the Gotha. Their total length is 2.61 m. Their chord varies from .53 m. inside to .75 m. at the projecting portion. The hinges of the ailerons are parallel with the lead- ing edge of the wing. They are attached by means of pins or bolts threaded through hinge loops, held in place by keys, on the system employed to attach the ailerons on the Roland fighter D.II. The arrangement has the advantage of permitting the quick attachment of the mem- bers. The lower wings, following the present tendency of German aeroplanes are rounded at the ends and taper at the rear, as in the D.F.W., Rumpler C.IV., and Albatros C.IV. Their maximum chord is 1.59 m. The aileron cables pass through the interior of the lower wings. The interplane struts (two pairs on either side of the fuselage) are constructed of streamline timber 105 m. in Rear view of the L.V.G. biplane: type C.V. S1NCI.K MOTOKK1) A I .K< >1'L.\ M .x \ \ii-w nf tail inrnilirrs (lianu-tcr. and t.-ipiTnl towards Imth i-iuls. Bv reason of tin- differing dihedral of angles the inside and outside struts :irr not thr same length. Tlii- outer struts are 1.6.S5 m. long and the inner ones I.:.!" in. Tin gap between thr wings is 1.71 m. at tlie fuselage .-iixl I t'lii in. in linr with thr rxtrrn.il struts. Thr total lifting surface is i j ;i M |. m.. that of the up- per plain- hriii^ -.':!. 7S sq. m., and the lower 19.17 sq. m. Tin- rah.-nir struts an- in thr form of an " N." inclined towards tin- ri ar. and converging to the fixed centre sec- tion of thr upper plane, tin- width of which is .IS m. The Tail Tin- sh.-ipr of tin- stabilizing plane, or fixed tail plane, resembles that of the Albatros fighter. Thr tail plane consists of two separate parts attached our on each side to a fixed section embodied in the fuse- which like it is constructed of three-ply. Thr elevator is a single flap, with rounded corners and balanced by a triangular extension at each end. The test width is :i.(H m. and the depth .65 m. The small triangles have a base of .39 m. and are .39 m. high. At the outer angle of each of the tail planes one finds a projection of about .040 m.. intended to eliminate vi- bration from the tips of the balanced ends of the eleva- tors by screening them from the air blast. The balanced rudder is placed above the elevator, and forms with the fixed fin an oval inclined backwards. Tin- fixed fin is constructed of -three-ply, and is trape- oidal in shape. The total height of the vertical empen- nage is 1.068 m.; its depth is .675 m. (1.15 m. including tin compensated portion). The internal structure of these members consists of steel tube-work. The control cables pass through the fuselage, coming outside l.."i() m. from its extremity; one pair of the ele- vator cables pass through a channel in the thickness of the stabilizing plain . The fuselage is entirely built of varnished three-ply, and is rectangular in form, with a well-rounded top. the uiuii rside being slightly less rounded. The sides have a slight outward bulge, accentuated at the level of the pilot's seat. The Power Plant The I..V ( . i \ . is driven by a Garuda airscrew, type A view of the rvlmiist in.iiiifoM V., with a diameter of .S.oi m. The boss of the airscrew is enclosed in a " Casserole," or pot. .58 m. diameter. The motor is a 225 h.p. Hen*, also used in the D.I \\ and F.1XH.G. II. It is fed by two tanks, with a capacity of 249 litres. On the upper left wing is fitted a feed tank. The con- tents of these tanks permit of a flight of almut 3' , hours. Tin up|M-r portion of the motor is entirely covered in with a panelled and removable sheet steel bonnet. The exhaust is led overhead as in the Kumpler ('. IV. Contrary to that machine it is not much curved, but rises nearly vertically. The honeycomb radiator, the capacity of which is 35 litres, is placed in front of the wings. It is rectangular in shape, and is attached to the eabanc struts by two brackets. Its upper part is attached to the fixed centre section of the upper plane by a small steel tube fork. Tin temperature regulating blind placed in front of the radiator is one of the best in use. It is simpler and more rational than the system of shutters. It consists of a movable blind of strong fabric, which is rolled and unrolled at the will of the pilot, which permits the stop- page of the passage of air and the regulation of the cool- ing. Accommodation The accommodation for the pilot is of oval form, the bigger dimension being in the direction of travel. Very close to this is arranged the passenger's seat in- side a turntable .86 m. in diameter, which carries a " Para- belltim " machine-gun. In front and on the right side is a Spandau machine- gun firing through the airscrew, and controlled by a Bow- den wire. Wireless apparatus is installed. The landing carriage consists of two pairs of streamline " V " struts built of timber, and a pair of wheels 810 mm. x 1 '2!> mm. The wheel track is 1.98 m. The axle is placed in a streamline wooden fairing. As in the Rumpler ('.IV., a drag cable runs from tin- front of the fuselage to the base of the inner interplanc strut. Tin- tail skid, which is attached to a small fin uinl. r neath the fuselage, is const ructed of wood, and i termi- nated by four steel laminations ,M)< m. thick. The skid is sprung with elastic cord. The Ace-Motored Single Seater Ace Biplane The small light, economical single-seater ACE Biplane has been designed to answer certain requisites as follows: Its wing spread of only 28 ft. 4 in., overall length of 1 8 ft., and 7 ft. height insure a very small and economical hangar for housing and workshop facilities. It is strictly a one-man machine, not only in flying but in being handled on the ground as well, as one man can pick up the tail and easily pull the machine into the hangar alone without aid of mechanic or extra help, because of its lightness. The performance of the ACE embodies the best assets of commercial aviation, such as a quick take-off, fast climb ( wide range of flying speed, slow flat glide with a twenty-five mile per hour landing speed and a very short roll which averages about sixty feet after the wheels touch the ground. To the above qualities are added the items of moderate cost and upkeep. The selling price being $'2,500 places the machine well within the reach of any pilot and the maintenance is one-third that of the average aeroplane. Gasoline consumption is under five gallons per hour and with a twelve gallon tank one has a cruising radius of two and one-half hours. High grade construction is the first requisite which proves itself in giving a factor of safety of over 8. An- other feature is the short space of time in which the machine can be assembled, due to the self-aligning fixed strut construction which eliminates the necessity and ex- pense of an expert aeroplane mechanic. The machine has been designed with the idea of it being used not alone as a single-seater sport plane but for com- mercial purposes as well; such as carrying mail, light ex- press, advertising, exhibition work, and to be used by 204 aerial police forces, etc. In recent test flights one hundred and eighty pounds of sand was carried in the spare space of the machine, in addition to a full load of fuel and the pilot. No notice- able depreciation in climbing was observed. This speaks well for the efficient design and proves that the machine can carry extra weight. The machine was tested out at the ACE Flying Field, Central Park, L. I., by the Company's test pilot, Bruce Eytinge, formerly a First Lieutenant Instructor and Test Pilot in the Royal Air Force for 18 months. On the first altitude test a height of 6000 feet was reached in 20 min- utes and later 8000 feet was reached in 28 minutes. Per- fect stability and height climb were observed at this alti- tude. On flying level the throttle was retarded 50 per cent, and the machine proceeded in straight horizontal flight flying level on half the motor's r.p.m.'s. When the throttle was entirely retarded idling the motor the ma- chine nosed down into a slow flat glide. Other tests of the machine's speed show that with full throttle it is capable of 65 m.p.h. In testing the gliding quality the pilot began a glide from an altitude of 8000 feet over Mineula at a distance of about 8 miles from the flying field and continued in the glide past his field to Amity ville. a distance of about a 11 mile glide and then turned back to glide into the airdome. In this maneuver a time of 1 5 minutes elapsed before the ground was reached and a landing was made about 20 feet from the hangar with a dead motor. The above test shows that in case of a forced landing from an altitude of about 3000 to 1000 feet the pilot will have ample time to select landing field within a radius of 10 miles. SI\(,I.K MOTOKKI) AEROPLANES The Ace in Hight and after dim bing to 8000 feet in M minutes Safety Factor Selected \\Ysteni spruce is used for all principal parU of wings, struts and fus< -lagc. etc. The complete whiff structure iiiuler a sand load test have supported in excess of ten times the weight carried in flying. Flying tests have shown a high factor of safety under difficult condi- tions of /.ooming. tail slide and whip stall, loops, spinning nose dive, inuncrinan turns and falling leaf. etc. The inai-liine is so designed that it has great inherent stability and if the controls are released when stunting the machine will right itself from any position. Assembling Facility One does not have to be an expert aeroplane mechanic to tinerate and assemble the ACK Biplane. This item is expediated by the employment of only two flying wires, two landing wires, two drift and two anti-drift wires, and two drift struts. The fixed stagger and angle of inci- dence are obtained through the employment of special single self-aligning struts. The lower planes have a 3 dihedral angle while the upper planes are neutral. General Specifications Span, upper plane Jfl ft. 4 in. I-enjrth. overall 1H ft. I l.-i|rtit, overall 7 ft. 6 in. Wheel tread 60 in. \Vhtfl iliiunrter 36 in. Siie of tire i6 in. x 3 in. Controls Lateral and longitudinal balances are operated by stick ontrol. The rudder is ojx-rated by a foot bar. All con- Ilinir surfaces are large and balanced affording ease of itrol and the response is so immediate as to require but i slight movement of the control stick or rudder bar. All nntrol wires are assembled in duplicate seta. Fuselage The fuselage is of good streamline form. It is of War- ren-truss construction. The cockpit is of 3 ply veneer. I age is braced with piona wire from the pilot's kpit forward, and with T section struts diagonally stag- gered from the cockpit rearward, eliminating all wires and The motor and members bearing heavy stresses are attached to a substantial pressed steel nose plate. The motor is bolted directly to the plate, and by eliminat- ing engine beds every part of the motor is immediately MCeadbfe. This is the most rigid motor mounting ever furnished in any aeroplane ami the absence of vibration is a noticeable feature. The nose is covered with alumi- num, the hood being arranged in quick detachable sections giving easy access to the motor. The remainder is eo\ ered with linen, doped, colored and varnished. The body tapers to the rear on which the double cambered rudder is hinged. On the instrument Imard in the cockpit to the pilot's left is the ignition .switch and choke wire, to his right is the gasoline throttle and in the center an oil pres- sure gauge, radiator thermometer, a revolution counter and an altimeter to indicate height. Landing Gear The chassis is of the ordinary V type, each V con- structed from one piece one inch tubing. Elastic chord shock absorber binds the axle to the struts. An under- carried skid of hickory fastened to the center of the nxle and braced with two streamlined tubular struts prevents the nosing over and eliminates the ever present danger of damage from overturning. In landing the tail of the skid acts as a brake, bringing the machine to rest after a very short roll of about 6<) feet. This feature makes the machine the safest and most suitable for small fields. Tail Group The tail plane is a fixed stabiliser of single cambered surface to which is hinged the balanced elevator flaps. The vertical fin is a fixed stabiliser of double camber to which is hinged the balanced rudder. The large bal- anced controlling surfaces and the undercarriage skid make this machine the easiest and safest to taxi, as OIK can easily taxi in a straight line or make a turn in a very small space. Motor Group An ACE four cylinder sixteen valve head. 4O h.p., water-cooled motor is used. The motor has been so care- fully balanced as to entirely eliminate vibration. Its weight is 146 Ibs. The cooling system is Thcrmo-svphon with ample water capacity. A five foot pro|>cllcr is 206 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A skeleton view of the "Ace," showing construction driven direct from the crank shaft at 2000 r.p.m. A spinner is used on the propeller over the hub and is so attached in front of the motor so as to form with the rest of the body a perfect streamline with low head resistance and giving a very neat appearance. The Atwater-Kent battery ignition system is used which affords ease in starting. Lubrication is full force feed by a spur ge; pump. Gasoline system is gravity feed from a 12-gallo tank in front of the pilot and separated from the mote by a fire wall. Zenith carburetor is used which afforc economic and efficient carburation. The I.oening Two-Sea er Monoplane, equippt with a :!00 h.p. Hispan Suiza engine. The Bristol Monoplane, equipped with a Le Rhone engine. This machine has a wing span of 30 ft. 9 in.; length over all -20 ft 4 in.; chord 5 ft. 11 in.; wing area 145 ft. SIN(;i.K MOTOKK1) .\KHUIM..\\KS HANNOVFRANFR B1P 5PAN LANE. 96' Si- s' I0r y f r s ^ / The Hannoveraner Biplane M ncrallv s| akin;;, the construction is of wood through- lit, si,, 1 hcing U se,l sparingly, except in the intcrplanc truts. landing chassis struts, c. ntn- section and some de- iils of the tail. The construction throughout is sound, and the finish uit<- i;ood. Tin performance- of the ni.-iehine is good. The leading particulars of the plane arc as follows: Vci^ht. Kmpty. l.?:l.' |li>. nt.-d Weight. .',-.;.' His. rr.-i of Ipp.-r Winers. _>|7.(i si|. ft. ir.-.i ,if I.,, WIT Wiiijfs, H_>.J sq. ft. nl. -i I \re;i ul \Viri(rs, Hiid.o S (|. ft. ilin^ pi r s.| ft. of \Viti(t Surfnee, i.Jfl Ihs. irrn of Aileron, each. lli.J MJ. ft. irrii of Hiiliinee nf Ailrnin. l.fi M). ft. iren of Top Pl.un- or Tail, KM) si|. ft. n-;i of It, .11, MM Hum- of Tail, !!!..' s<|. ft. il Vr.Ni of Tail Plane, ...> s |. ft. i Kin, (i.j sq. ft. approx. rca of Kiiil.lrr. li.t sq. ft. f Kleuitors, J.'.o si|. ft. lori/ont.il \n-;i of |li H ly. .VJ..' sq. ft. <-rtii-;il \rra of Body. II I. li -n. ft. till \Veifrht prr h.p., H.U His. p ( -r h.p. re. Pilot mid Ohscrver. riii.Hiient. 1 Spanclnu Orin^ throiifrfi propeller. 1 Pcrnhellum mi rinjr mounting. fini-. (ipi-l \r^ns. I MI h.p. rtrol Capacity, :(7 > , jrallons. ity. :i Dillons. Performance ) Climb to i,000 feet, 1 min-.. Rate of climb in ft. prr mln^ 490. ln. Kcvolutions of Knjrinr. 1,444. Speed At 10,000 ft. 96 miles an hour; Revolutions, 1,464. At 13,000 89'/ z miles an hour; Revolutions. l.:,_><>. Service ceiling at which rate of climli is loo ft. p,- r mi,,., U.OOO. Kstimateil absolute ceilinfr, 16,400. Greatest heifrht reached, M.MHi in :t;i n,ii,s. in sees. Hate of climb at Ibis beipht, IJO ft. per mill. Air endurance, nlnnit .'_. hours nt full sprrl at |(i,(HK) ft., j n . cludiii); climb to this height. Military load. 444 Iba. The machine is nose-heavy with the engine off. and slightly tail-heavy with the engine on. It tends to turn to the left with the engine on. The machine is generally light on controls, except that the elevator seems rather insufficient at slow sp.-cds. It ia not very tiring to fly. and pulls up very (juicklv on landing. The view is particularly good for hoth pilot and oli server. The former sit.s with his eyes on a level with the top plane, and also enjoys a good view below him on account of the narrow chord of the lower plane. 208 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Rumpler Two-seater Biplane with 160 h.p. Mercedes engine Halberstadt 160 Mercedes It was reported that the center thrust and the center of resistance of the plane were too far apart, so that there was a tendency to stall with the engine on, and to dive with the engine off. Directionally, owing to propeller torque, the machine would swing to the left, but, with engine off, would be neutral. Controllability and manceuverability were good. Details of Weight and Load Carried Weight Average total weight of machine fully loaded 4,220 Ins. Load Carried Pilot 18 lhs - Observer 18 lhs - Vickers gun Lewis gun Deadweight Standard Height 10,000 13,000 15,000 16,000 Speed M.p.h. 117.5 113.5 110.5 108.5 Speeds at Heights R.p.m. 1,590 1,565 1,545 1,530 Speed M.p.h. 120.5 116.5 114 112 R.p.m. 1,725 1,700 1,675 1,665 16 Ibs. 134 Ibs. Total load 545 lbs - Carburetor, Zenith, 2,004, 2,394; jets, 289 main, 340 compensator. Climbs Result of Trials A. B. 8,781 X. 3,012m. R. of C. ft./min. R.p.m. A.s.i. (1,540) 1,040 1,620 71 875 1,615 70 600 1,605 69 330 1,580 67 275 1,575 66 StandardTime H.ofC Time Height Mins. ft./min. R.p.m. A. s.i. Mins. (1,365) 2,000 2.0 935 1,460 71 1.8 5,000 5.6 770 1,460 70 5.0 10,000 13.5 500 1,450 69 11.8 15,000 27.8 230 1,430 67 22.9 16,000 32.75 180 1,425 66 26.2 Trials at 4,500 ft. Giving Relation between Speed and Revolu- tions per Minute Flying Level Flow Gals./Hr. 25 81% 17 14% 12 10% 9 The installation of the 160 h.p. Mercedes is on the usual German lines with center section radiator, main pressure tank, and gravity tank in top center section. The wing structure is a single bay design with the bay longer than usual in proportion to the gap. There is a small anhedral angle on the top planes, and dihedral on the bottom. The center section is covered top and bottom with plywood. The fuselage is three-ply, covered and tapers to a hori- Speed Flow Speed M.p.h. R.p.m. Gals./Hr. M.p.h. R.p.m. 124 1,600 24 127 1,760 120 1,560 21 120 1,685 11C 1,470 17y 4 110 1,575 100 1,375 14'/2 100 1,470 90 1,280 12y 2 90 1,365 80 1,185 10% 80 1,260 70 1,085 V4 70 1,150 SINCLK MOTOKK1) AKUOl'l.AN K.s 209 i- nf tin- |MK!V of the Hallterstiidt two-seater biplane, 160 h.p. Mercedes engine. The Inset is a sketch of the tall plain-* zontnl inrinlirr. the width remaining constant. This al- lows the ri_-iil fixing for the tail plane, no bracing or struts being needed. The tail plane is adjustable on the ground only. Tin- pilot's and gunner's cockpit are constructed as one, with- out apparently weakening the fuselage. II I' at revolutions not known. Propeller Dia. 274 cm. Pitch, 900 cm. (marked). 2,747 mm. 3,095 mm. (measured). Military load 545 Ib*. Total weight, fully loaded 2,539 Ihs. W.-iirht ,>,T M). ft. 8.2 Ib*. \\ '. ijrht pr h.p. 15.83 Ibs. (h.p. assumed 160). M.p.h. H.p.m. S|-cd at 13,000 ft 8* 135J approx. S|.- ti\. ,| tail-plane is trapezoidal with a rounded Icad- :_' to its front part. Its greatest depth is 0.88 metres, its width is .' l : m.tres. A permanent portion of plvui> The section at the centre of gravity is 0.865 x 1.16 m. taken at the axis of the lower plane. Controls The control of the machine is effected with the aid of a control column with a handle formed of two branches sloping towards the pilot. The hand-grips are bound with cord. In the centre are two buttons which work the machine-guns. Thr control column can be fixed when climbing or diving by n little toothed wheel. The rudder bar is adjustable and the seat is fixed. Tin- starting magneto is found on the left-hand side in front of the pilot. Level with the pilot under the fuselage are two holes with plugs, to permit the draining off of oil. petrol, or water, which might damage the plywood if allowed to collect. .lust in front of the tail-plane there is found, on either side of the fuselage, an opening large enough for the passage of the hand. This gives a better grip when lift- ing the machine than would the bare fuselage. The tail-skid of special section is constructed of ash, and is reinforced by metal where it touches the ground. The springing of the tail-skid is effected by elastic cord. The airscrew in common use is an " Axial " 2.82 metres in diameter, placed underneath a revolving pot, or " cas- serole." On certain other Pfalz aeroplanes has been found the " Heine " airscrew, 2.78 metres in diameter, or yet again the " Imperial " airscrew 2.70 metres diam< r The Engine The engine is a modified I60-!i.p. Mercedes, c<|iiippcd with double ignition, and a horizontal exhaust pi|>c on the right-hand side. The form of the exhaust pipe \ m- s In certain types it is a cornucopia, and the emission nf gas l made in front of the first cylinder. On other ma- chines the end of the exhaust pipe is taken in the reverse direction, the exhaust being emitted, instead, at the rear of the last cylinder. 212 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The engine cowl leaves the upper part of the cylinders uncovered. The petrol supply is provided by a main tank of about 70 litres capacity, placed in front of the pilot on the floor of the machine, and by a tank built into the upper plane with a capacity of -10 litres. In all, 110 litres of petrol are carried and 15 litres of oil. The radiator is of the system of layers frequently em- ployed in chasing machines. It contains 40 litres of wa- ter. On its lower face is found a large aluminium plate fixed in two grooves, which makes it possible for the pilot to cover or uncover the radiating surface. Armament. This consists of two fixed Spandau ma- chine-guns operated by the engine, and firing through the airscrew. They are arranged one on each side, a little above the cylinders, and can be fired separately or to- gether. The Landing Carriage. This is formed by four streamline steel tubes 50 by 30 mm., which constitute two "Vs." The two front legs are joined by an arched strip of metal which supports the front portion of the fuselage. A lug embodied in the upper extremity of eacli strut forms the attachment of a cable running to the front interplane strut. The steel axle, 53 mm. diameter, is placed between two wooden pieces. A movable and hinged plate covers the whole arrangement, and acts as a streamline fairing. The suspension is rendered elastic with the aid of metal springs covered with fabric, arranged like rubber cord. A metal cable limits the travel of the axle. The track of the wheels is 1.72 metres. The wheels are fitted with 760 by 100 mm. tires. Below is given a summary of results on tests of several German aeroplanes : View from above of the German Pfalz single-seater fighter, showing rudder construction. SINC.I.K MOTOKK1) A KHO1M ,.\ \ | g Vr- '214 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Pfalz Scout 828 4 17 160 Mercedes The performance of this machine appears to be prac- tically the same as that of G/141 Pfalz Scout with 160 h.p. Mercedes, tested in March, 1918. Summary of Results gib u Q d .5 5 ._: 1.5 = o< 5 p. 1 jj BS 4) d j H ^ PS ^ pa < (1,335) (1,320) 5,000 7.0 606 1,370 67 6.9 605 1,330 73 10,000 17.3 373 1,350 61 17.5 360 1,310 57 14,000 32.3 187 1,320 54 33.7 160 1,290 61 Standard Height 10,000 Speed M.p.h. 98.0 R.p.m. 1,415 Speed M.p.h. 102.5 R.p.m. 1,400 13,000 94.8 1,395 96.0 1,355 Details of Weight and Load Carried 8,284/17 G/141 Military Load 3l ". 281 Ibs. Total Weight, fully loaded 2,085 Ibs. 2,056 Ibs. On this machine lift wires have been added to the over- hang, running from bottom rear main plane fitting to about half way along the back spar overhang. Front openings have been cut in the engine cowling to the cylinders, the former Pfalz being left plain. The tail plane has been increased from 12.1 sq. ft. to 16.2 sq. ft., but the shape has been altered, being now nearly semi-circular. Main plane incidence and tail plane setting are approxi- mately the same. Trials on Aviatik No. G.H.Q./4 Duty Reconnaissance. Engine Benz. Assumed 200 h.p. Propeller Wotan. Dia. 3,004. Pitch 1,650 (measured). Military load 545 Ibs. Total weight fully loaded 3,325 Ibs. Weight per sq. ft. 7.46 Ibs. Weight per h.p. 16.62 Ibs. M.p.h. Revs. Speed at 10,000 ft 9?i/ 2 MOO Speed at 15,000 ft 89'/ 2 1,510 R.ofC. Indicated Min. Sec. ft./min. Air Speed Revs. 19 45 345 63 1,490 40 15 165 58 1,470 Climb to 10,000 ft.... Climb to 15,000 ft.... Service ceiling (height at which rate of climb is 100 ft. per mm.) 16,750 ft. Estimated absolute ceiling 19,500 ft. Greatest height reached 1 7,000 ft., in 5(i min. 20 sec. Rate of climb at this height 90 ft. per min. Dimensions and Equipment of the 1918-1919 Types of German Aeroplanes The following table permits readers to compare the points of the fighting German aeroplanes : Machine Type Albatros D. II Albatros D. Ill Torpedo D Roland D- II Halberstadt D Fokker Rex D- II Roland C A. E. G C. IV L. V. G C. IV D. F. W. Aviatik C. V Albatros B. F. W. . . . C. V Rumpler Gotha G. I. A. E. G ' r ' 1i 5* Span Upper Lower ft. in. ft. in. 07 s OR 1 Gap ft. in. 4 Chord ft. in. 5 3 Length Over All Motor ft. in. 24 O MprppHps "3 1! 175 s . E 2 6 C "9 g 28 g 4 10 4 10 24 Mercedes 175 2 Mercedes 175 2 29 g 28 o 4 4 4 9 22 fi 175 2 28 6 25 9 4 3 4 10 24 Mercedes or Argus . . . 120 2 29 6 20 6 4 3 4 10 24 Mercedes or Oberursel 175 9 33 33 4 o 5 3 175 1 a 42 g 41 g a 5 5 23 g 175 2 4 n 44 g 6 5 28 235 2 4 -i 43 g 42 o 5 g 5 9 228 2 6 a 41 3 40 o 5 10 5 10 28 o 225 a 4 a Mercedes 260 2 6 g 78 79 7 a 7 g 41 o 520 3 14 3 Two Benz . 450 2 .. ''' A tf (/ \ I/ GERMAN 'TYPE. C IV &UMPLEQ Z60 HP I9IT MPLANE Jcale of feet I^^^T"~I M I T I T T I *> i * 'Q " Mclaughlin 215 216 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The German Rumpler Biplane The C. IV Rumpler Biplane The Rumpler biplane described below is a general util- ity machine, and is perhaps the best in its class. It is chiefly of interest on account of its great speed, which is equal to that of a chaser single-seater, and also on ac- count of its high "ceiling" (6.500 metres). The climb of the Rumpler C.IV is also very good (5000 metres in 35 minutes). General Specifications Span, upper plane 12.60 Metres Span, lower plane 12.10 . Metres Chord, upper plane 1.70 Metres Chord, lower plane 1.30 Metres Area, upper plane 20 Sq. Metres Area, lower plane 13.50 Sq. Metres Gap between planes 1.85 Metres Stagger 0.60 Metres Overall length 8.40 Metres Overall height 3.25 Metres Engine, Mercedes 260 h.p. or Mayhach 250 h.p. Climb in 35 minutes 5,000 Metres Wings Both upper and lower wings are swept back 3 degrees. There is a dihedral angle of 2 degrees and the wings are staggered forward 0.60 metres. The trailing edge, con- trary to usual German practice, is rigid. The ribs, which are made of three-ply wood, pierced for lightness, are spaced 0.30 metres apart. Their angle of incidence is uniform and is equal to 5 degrees. In the plan the upper wings are of trapezoidal form, with rounded angles. Above the fuselage the trailing edge is cut out as shown in the illustrations. The maximum chord is 1.70 m. In each of the upper wings there are 19 main ribs, and five compression struts of steel tubes. The ailerons are of the tapering type, their chord vary- ing from 0.50 to 0.65 m. The lower wings, as in so many other German machines, have rounded wing tips. As the radius of the arc forming the rear edge is longer than that of the front, the wing tip somewhat resembles that of a propeller blade. Each of the lower wings has 17 main ribs, and four steel tube compression struts. The interplane struts, of which there are two pairs on each side of the fuselage, are oblique. In section, the inner front struts measure 0.105 m., and the rear strut 0.130 m., while the outer front strut measures 0.090 m. and the rear outer strut 0.085 m. The gap between the wings is 1.85 m., and the total lifting surface is .S3. 5 square metres, of which the upper wing is 20 square me- tres and the lower wing 13.5. Tail The tail plane, which is not adjustable, is not so deep as in previous types. In plan, the leading edge of the tail plane is approximately a semi-circle. This tail plane is supported on each side by struts attached at their other end to the bottom rail of the fuselage. Two other struts brace the tail plane to the vertical fin. The struts under the tail plane are provided with a series of sharp-edged metal points. It appears probable that the object of these is to prevent the landing crew, when wheeling the machine about, from catching hold of these struts, thus possibly bending them. The elevator is in two parts, each of which is partly balanced by a triangular forward pro- jection. The rudder, which is built up of metal tubes, is of the usual type, and the control cables pass inside the fuselage, guided at points through small wooden tubes. Fuselage The construction of the fuselage is of the current type, with four longerons and struts and cross members, braced by piano wire. Front and rear are covered with three- ply wood, and the middle with fabric. The propeller (ai Heine) has a diameter of 3.17 m. As on all other Ger- man machines, the propeller boss is enclosed in a " spin- ner." Engine The motor fitted on the Rumpler is either a 260 h.p. SINC;i.K MOTOKK1) A KK( >1'1 . \ \ I - -.'IT \ liMMipl.-r type of German machine. Vote the lo.v.ti,.i. ..f the radiators Mcrrr.lrs or a -'.-><> h.p. Maybach. both having six v. r tical cylinders. When Hi. Mere,-,!.-, i, titt.-d, it is slightly tilted to the right, in order to allow thr induction pipes to pass between tin- legs of thr cabanr. With tin- May bach, which offers less riiriinihr.-inrr. this arrangement is not necessary. The motor is supplied with furl fnnn two tanks. The main ,,n, (about -."Jd litrrs) is placed under tlir scat of tin- pilot, thr second, the serviee tank (about 70 litres), is pla, -,,! ,t the back of thr pilot between him and the gun rim: in thr Dinner's ,-oekpit. The quantity of fuel car- rird allows of a flight of four hours' duration. The eov- ering over Hi. mgine leaves the top of the cylinders ex- posed, .-.n.l encloses a Spandau machine gun operated by tin- motor. The exhaust pipes run from the six cylinders to a cor mon chimney, eurving upwards and backwards. The cliiiiinev itself is ,liided. about half way up, into three l.ranehrs. probably in order to obtain a certain amount of silencing effect. As in previous mod. Is. the radiator, which is semi-circular in shape, is placed on thr front ,-f the eahane. In front of it is a series of small slats, whirh can hr moved so as to be either parallel to or at right angles to the direction of flight. This is, of course, don, in order to make it possible for the pilot to adjust the cooling according to the altitude at which he is Hying. Behind the motor is the pilot's cockpit, and behind again that of the gunner. Supported on a gun ring in the rear cockpit is a Parabellum machine-gun. Pilot and gun- ner are very close together. In the gunner's cockpit there is a bomb rack of the usual type, carrying four bombs. An opening in the floor permits of taking photographs, and the machine carries a wireless set. Thr landing chassis is of the V type, with rubber shock absorber.. There is no brake fitted on this machine. An external drift cahlr runs from the nose of the fuselage to the foot of thr inner front interplane strut. rrman Rumpler type machine CURTI5S 18-1 400 HP 'K-12 ENGINE TRIPLANE Scale of Peet McUugtilij 218 SIM.I.K MOTOKK1) A KHO1M ,.\ \ I - The Curtiss Model 18-T Triplane This machine was designed for speed and great climb- ing ability. General Dimensions Wing Span I'pper Plane 31 ft. 11 in. Wing Span .Middle Plane 31 ft. n in. Wing Span Lower Plane 31 ft. \\ fa Depth of Wing ford (I'pper, Middle and Lower) 44 in. Gap iM-tween Wing- (In-twccn I'pper and Middle) 43 in. Cap iMtweeii Wing- (between Middle and Lower) 3*^ in. r None Length of Machine overall 93 ft. 3^ 8 in. Height of Machine overall 9 ft 10% in. Angle of Incidence gy t degrees Dihedral \ngle None ;>l>ack 5 degrees Wing Curve Slonnc 'iilal Stabiliser Angle of Incidence 0.5 degrees Areas Wings-- I'ppcr .' 119.0 sq. ft. Wing-- Middle 87.71 sq. ft. Wing- Lower 87.71 sq. ft. -on- (Middle 10.79; Lower 10.79) SIM sq. ft. llori/.ontal Slahilicer 14.3 sq. ft Vertical Stiibiliser 5.;.' sq. ft. ..rs (each 6.51 ) 13.09 sq. ft Hiiddcr 8.66 sq. ft. Total supporting surface 309.0 sq. ft. Loading (weight carried per sq. ft. of support- 9.4 Ibs. ing surface) Loading (per r.h.p.) 7.35 Ibs. Weights Weight Machine Empty 1,895 Ihs. u eight Machine and Load 9,901 Ibs. f-efiil I ..ad 1.076 Ibs. Fuel 400 Ib*. Oil , 45 Ibg. Pilot and Pits.eiurer S30 Ibs. Useful load au\ |bs. Total 1.076 Ibs. Performance Speed Maximum Horisontal Flight 163 m.p.h. Speed Minimum Horisontal Flight 58 m.pji. Climbing Speed 15,000 ft. in 10 minute* Motor Model K-1J18-C) Under, Vee Four-Stroke Cycle. Water cooled. Horse Power (Rated) at 9,500 r.p.m. 400 Weight per rated Horse Power I To Bore and Stroke 4% x 8 Fuel Consumption per hour 36.7 gals. I in I Tank Capacity 67 gaU. ( >il Capacity Provided Crankca-c 6 gauu Fuel Consumption per Brake Horse Power per .55 Ibs. hour 030 Ibs. Oil Consumption per Brake Horse Power per hour Wood Material Cl.ickitc Propeller Pitch according to requirements of performance. Diameter according to requirements of performance. Direction of notation (viewed from pilot's seat)... Details One pressure and one gravity gasoline tank located In fuselage. Tail skid independent of tail post; Landing gear wheel, sixe X In. x * in. Maximum Range At economical speed, about 55O mile-. Three-quarter rear rtew of the Curtiss Model 18-T Triplane with a 400 Kp. Curtiss Model K engine 220 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING SINC1.K MOTOKK1) AKKOIM.A NKS -'_' I ThriT ijiiarlrr re.-ir \ lew nf the Sopwilh TripL-inc. Vote tin- single struts and the uilrnms mi nil Hirer .: The Sopwith Triplane What prnli.ilily has led to the return of the triplane form of construction is tin- small span which it en- .ililt s n, to use. Another advantage of the triplane arraiigi nn nt is that tlif aspect r.-itio, which .should not he less tli.-in il. hut which in many machines of sii.irt span often has to It- considerably less, can be more easily ar- ranged for in the triplane. Thus in the case of the Sop- with triplane the chord is only little over 1 metre, and the span is 8 metres. The increased wing resistance is counteracted by the employment of only one strut on each .side anil a very simple wing bracing. Furthermore it is possible, owing to the light loading of the wing*, to con- struct the wing spars considerably lighter, and still have a comparatively great free length of spar, in the case of ~ MM ith triplnnes about 2.75 m. with an overhang of l.Ni in. Tin- weight of the total wing area will there- fore sc.-ircely come out greater than in the case of a bi- plane of the same area. Possibly also the arrangement of the wings is advantageous as regards the view obtained by tli>- pilot, as the middle wing is about on a level with nd the upper and lower wings, on account of tin ir small chord, do not obstruct the view to as great an extent as the wings of the ordinary smaller biplane liavini: i greater wing chord. While both lift wires pass in front of the middle wing, the landing wire runs through it. The bracing cables for the body struts are crossed in the ease of those running forward to the nose of the machine, while those bracing the struts in a rearward >n are straight. The gap between the wings is !>n centimetres, and the stagger is about 25 per cent. All ngs are fitted with wing flaps connected by a ver- ei-1 band. In the nose the body carries a 110 h.p. t rotary motor, enclosed in a circular cowl, which s below the body in order to allow the air to escape. Tin- body is of rectangular section, rounded off in front by M ans of a light wooden framework in order to make it merge into the curve of the engine cowl. The width of the fuselage is 0.70 m., and it tapers to a vertical knife- edge at the back, to which the rudder is hinged. The elevator is in two parts, and has in front of it a tail plane of about 3 metre span, which, as in all Sopwith machines, can have its angle of incidence adjusted during flight. The area of the Sopwith triplane is 27 square metres, so that for a total weight of 670 kilogs. the wing loading is only 2. r > kilogs. per square metre. With such a light loading the machine has undoubtedly a considerable speed and a very good climb. Further particulars relating to these have not yet U -en published up to the present. The triplane is built both as a single-seater and as a two- seater, and has always a fixed machine-gun in front above the fuselage, and in the ease of the two-seater another machine-gun operated by the observer. This increase* the weight of the two-seater by about KM) kilogs. The under-carriagr consists, as in all Sopwith machines, of two V's of steel tubing and a divided wheel axle. Un- hinge of which is braced from the fuselage. The following remarks are taken from a technical re- port: The fuselage with tail plane and rudder is the same as that of the small Sopwith single-seater biplanes. The three wings have a span of 8.07 m. and a chord of 1 m. The lower and middle wings are attached to short wing sections on the fuselage. The upper plane is mounted on a small center section supported by struts from tin- body. Both spars of the upper wing are left solid, while those of the lower and middle are of I-section. The interplane struts, which are of spruce, and of streamline section. run from the upper to the lower wing, and the inner ones from the upper wing to the bottom rail of the fuselage. In order to give a better view the middle wing, which is on a level with the pilot's eyes, in cut away near the fuse- lage. The wing bracing is in the form of streamline wires of '/4"' n - diameter. The very simply arranged landing wires are in the plane of the struts, while the bracing of the body struts, as well as the duplicate lift wires, are taken further forward. From the rear spar of the mid- dle wing, wires are run forward and rearward to the up- per rail of the fuselage, and the lower wing also has a wire running forward to the lower rail of the body. All the planes have wing flaps, and inspection windows of celluloid are fitted over the pulleys for the wing flap cables. The motor is a 110 h.p. Clerget, and the petrol is led to the engine by means of a small propeller air pump mounted on the right hand lody strut. As the air screw was not in place we cannot give details of it. In tin- pilot's seat were the following instruments: On the right 222 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A British pilot preparing for a flight in a Clerget-motored Sopwith triplane hand wheel for varying the angle of incidence of the tail planes, a hand operated air pump and a petrol indicator. In the middle, air speed indicator, manometer, clock, revs, indicator, and switch. On the left a petrol tap, lever for regulating the air, and lever for regulating the petrol. The weight of the machine empty was found to be 490 kilogs., and if the useful load is assumed to be 200 kilogs., we obtain a total weight of 690 kilogs., which, with an area of 21.96 sq. metres, would give a loading of 31.4 kilogs. per square metre. Further, the following particulars are given: Motor: Clerget, nominal h.p. 110, brake h.p. 118; fuel capacity for two hours, petrol 85 litres, oil 23 litres; area of wings and flaps (square metres), upper 7.90, middle 6.96, lower 7.10, total 21.96; area of elevators 6 by .5, of wing flaps 1.10, of rudder .41. Angle of incidence (degrees) : upper wing, root -(-I, tip .8; middle root -f- 1.5, tip -)- 1.5; lower, root -)-.5, tip .5 ; tail plane, variable -{- 2 to 2 degrees. Loading per sq. metre, empty 22.3, fully loaded 31.4; loading per brake h.p. empty 4.15, fully loaded 5.85. At economic speed, about 550 miles. Fuselage with under-carriage and accessories .... Wings -. Tail plane, rudder and elevator Engine Petrol tank Oil tank Propeller Engine accessories Mounting Total weight empty Pilot Gun and ammunition 85 litres of petrol and 23 litres of oil Weights in kilograms 133.5 135 13 160 15 8.5 10 16 3 Total weight, useful load 490 80 40 80 -'00 Interior of the Sopwith factory, showing one of the triplanes being assembled, and in the background the biplanes MULTI-MOTORED AKKoi'l.AM.s 228 The remarkable " baby " Caoroni triplane scout, the smallest member of the Caproni family, Mr. Capronl standing by Sim-,- UK- War, both the Cnpronl biplane and trlplanr have been remodelled for paswnp-r travel or rommerrial purposes. __ !.,,,! ,,,. I,..., lH-,-n litti-d with H rabin to accommodate eight JMTV.M-: outside there arc seat* for the two pilots and for nn..tbrr rnn-hnnic; iimlrr thr p.isM-nger seat* then- U riM.in for J>*> ll>v of mail. Thr hiplalir roinnnlly ,.,rri.-. p . t ~,,\, -nr for 1 1..- triplane. equip|-d with three Liberty engines, has been fitted with a passenger rabln. with acrommodiition for inside and four others alwve. J-24 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Perspective Sketches of the German Fokker Triplane The upper sketch shows a three-quarter rear view of the Fokker Triplane. This illustration gives a good idea of the gene arrangement of this interesting machine. Xote the small veneer plane enclosing the wheel axle. Below is a three-quarter frtl view of the Fokker Triplane. The thickness of the wings can be imagined from an inspection of this drawing. The pin-jointl struts are really ties rather than struts as they are working in tension SI.\(.I.K MOTOKKI) AKUOIM.AM 9 The Fokker Triplane The Fokkcr triplane can IK- said to be of the " wire- ss " type. The internal construction of th. wings i^ .Jesigi,. ro\ iile nil the strength without anv external aid of anv tind. The interplane struts, which are really ties rather bin struts, might conceivably have been omitted alto rcthcr, and so tar as om is able to judge, their onl\ func- ion is to help to distribute the load more evenly b. tw.in he three wings. It is well known that in a biplane the ipp.r wing carries about four-sevenths of tin total load when the wings are of equal section, span, and chord > nd the lower wing about three scv enths. In a triplane tiucli the sum distribution is found, with the exception hat the middle and lower wing each take a share (not (|iial ' of the three sevenths of the total load. Ill the Fokkcr triplane the upper wing is of larger span han the middle wing, which in turn is of slightly greater pan than the low. r wing. In consequence, as the three iing~ appear to In- all of the same section, the upper wing itist carry more than four sevenths ot the total load. In rder to provide a licttcr load distribution, the middle and IIW.T wings are made to carry their share of the load n the top plane by connecting them to this ria thin high nen. ss ratio struts, which are in reality ties as they re working in ten* MI This explains why the struts re so ex) ninety thiii (about ' ._. in.) and the moment of nertia of the strut section would be so small that the truts would buckle under a very small load if subject to (impression The fact that no lift bracing is employed naturally wing spars of considerable depth if the spar rcight is to U' kept reasonably low. and in the Fokkcr riplane this has been attained by making the wing sec- ion very thick in proportion to the chord. Roughly, the i.ixiiiiiiin c tmh. r is in the neighborhood of one-eighth of T<1. wo wing spars are placed very close together, and ios. d in a box of three-ply wood. The function f this Itox is two-fold, it increases the strength of the l>-irs for taking bending and at the same time acts as it. rnal drift bracing. The upper wing, which is in one piece, runs right across, upported on struts sloping outwards as in the Sop- The other two wings each have a centre section igidly attached to the body, the middle one resting on the p longerons and the bottom one running underneath the wer longerons, an aluminium shield streamlining the >rmal surface presented by the deep flat sides of this imr. From the illustrations it will be seen that the gap is Uy small, being very considerably less than the liord. The inefficiency thus caused is partly made up staggering the wings but even so one would imag- ic tin- machine to be somewhat inefficient. The interfer- 1 ing to too close spacing of the wings chiefly affects ie lift co-efficient, and as the machine is probably very :htly loaded compared with the majority of German >' bin. s it is possible that the landing speed is not Strictly speaking, the Fokker is not a triplane. It would be mon correct to term it a three-and-a-half plane, as the wheel avle is enclosi d in i . ising of plywood which M soincMhat similar to that of the . p.rnnints h.,\c shown Hint floats ,.| ,uch a sift ion as to ply cambered top surface may be made to sup- port their ,.wn weight during flight. In the case of the Fokker triplane it ap| irs probable thai tins pi around the wheel axh , not inconsiderable load during flight. Its section ap|>-ars capable : porting a fair load per square foot of area, and its in effici. i to low aspect ratio is probably less than one wo::!d expect in a plane of an aspect ratio of dmut two. on account of the proximity of the ,-ov, -red in wheels to the tips, the effect of which must he to stop end losses to a considerable extent. As regards the body of the Fokker triplane tins is con- structinnally very similar to that of the Fokker mono I lanes. I ongcrons as well as struts and cross ni.in lers are in the form of steel tubes, and are joined together by welding. The internal bracing of the body is pe- culiar in that the bracing wires are in appearance in duplicate, although they are not so in effect. The arrangement, to which we shall revert again when dealing with the Fokker in detail, does not appear to possess any other advantage than that in each bay only half the nuinlMT of loops II.IM to be made in the wires. The tail plane, as well as the elevators and rudder, is mode of steel, and is of a symmetrical section, much thinner than that of the Albatros, but otherwise similar to it in that no external bracing is employed. While thin is quite satisfactory in the Albatros on account of the thick tail plane spars employed, it appears wholly inade- quate in the Fokker, as the plane is very thin, and since, moreover, the trailing edge of the tail plane is a steel tube, which section, as is well known, is not a good one for laterally loaded beam, owing to the fact that much of the material is massed around close to the neutral axil where it in not taking very much of the load. As exhibited at the F.ncmy Aircraft View Rooms the Fokker is not complete inasmuch as the engine has been removed. The cowling shows without a doubt that tin- engine must have been a rotary, and the mounting the type usually employed for rotary engines, i.e., a main engine plate holted to the nose of the body . and a pyramid of steel tubes, supporting at its apex the rear end of the crank-shaft. A sheet of aluminium is placed immediately in front of the engine plate. The manner of cowling in the engine will be apparent from our illustrations, and docs not present anything of particular interest, follow- ing, as it does, conventional practice. Although they are not in place in the machine M ex- hibited, it is evident from the aluminium eastings for the cartridre 1 rlts that two synehronis. d ni-ichine-giuiH have hi en t.:-il, one on en h side above the fuselage. The usual tri;-:-i rs. operating the guns through HowM AltINK NAVY TUAIMNC SI.AI'1 AM. Thr \rriim.iriin- Navy Training Seaplane. II is equipped with n Cnrtiss <>\ \<*> horse-power engine or the Acromarlne 1 in Imrsr power I'liirinr. This seaplane is of the single float type, a development of the Aeromiirlne twin float Seaplane which ha* been iiM-il e\teiisi\ely by the Navy Department. With the single float the marhine is easy to manumrer on the water Thr Ai-roiiiiirinc MiMlrl 1(>-T Flyinfr Boat is provided with a 100 horse-power Curtiss OX enfrine. This mnrhine has Iwn imrn*iatu operation. A hand starting lever is provide,! iminediatelv Sp " n , ri>|K ' r , 1 ^' in ' ? ' ' ** " " ,..,,. .spn Lower \\ me U ft. 11% In. behind the motor and has ,. sa t,sfactory service. As ,-,,, , ,, |M . r n * d ljomtT wln)t Mentioned before, the cooling system is mounted to the Gap 7.- in rear and above the motor. This mounting is exceptionally l^-ntfth over all .>: n. iii-p. in. eOVetive ; ind l,as performed .satisfactorily in service. The H-i|flit ovrr all . . I i ft. 1 1 depth 12 in. Motor Group The propeller, designed by the Burgess Company es- pecially for the speed scout, is 7 ft. 9 in. in diameter, with a 5 ft. 9 in. pitch. The motor is a Curtiss OXX-2 rated 100 h.p. at 1400 r.p.m. Fuel is carried for a flight of 2*A hours' duration. Curtiss Model H-A Mail Machine. Streamline has been carried to a very effective degree on the Curtiss Model H-A Mail Machine. The fuselage is exceptionally deep, wings being attached directly to the fuselage and a single pair of struts at either side. A Kirkham model K-12 engine is used, connected to a four bladed propeller with high pitch. The photograph fhows the neat way in which exterior control wires have been eliminated. SINUI.K MUTOKKI) A Kl{< )1M..\NKS I In- I 'nrti-s Mmli-l 1 1- A 1 1\ dm An unusual fr.iture in this III.H him- is ||M- sinjrlr pair of struts from thr pontiMia In tin- fiisrlagr, tin- dr<-|> liody anil tin- cliiiiiiiiitinn of struts lx-trcn tin- wii>|is ami Inxly. Thr II|>|T ]>lanr hits the customary (xisjtjvr ilili.-.lr.il hut the Inw.-r planes slo|..- downward in n negntivi- or rrvrrsrd dihedral. Thr Hydro rrrinli|rs in many respects thr H-.\ l-and Ma- <-liim- l>nt two sets of struts iirr used on thr Hydro l>ecmisr of the greater span. The Curtis* H-A Hydro Tin- ( nrtiss II \ Ilvilni is a two plan single flont sea- l>lain-. Tin- upper wing has > dihedral of S r and the lowi r pl.-uir a i-atlii-ilral of 1. Both plant's have an in- rnlrnri- of .' . a ml a swri-pliack of t'j . In official tests l<\ tin \ ,\ \ I > partiiu-nt tins inncl)ine ha.s made a sprcil of l.il.'i miles per hour with a full load. Its climbing spi . il li S.'.IMI t, it in ti-n iniiiiiti-s. 1 hi final is jii f.Tt long, .H ft. 6 in. wide and 4 ft. 6 in. ili i p. It has thri'i- planini; strps. The horizontal .stahilixer is adjustable during flight, within tin- limits of minus and plus 1. The machine i-arrii s four machinr-giins; two fixed Marlins and two hYxilih I.i w is Th. rimiiii- has a Liberty 1'-'. giving 330 h.p. It is l>er plnne .................................... 30 ft. l.owrr plnne .................................... 36 ft Cord ........................................... 7* in, Maximum ftp Minimum (rnp ................................... 4i'/, Overall hriffht ................................... 10 ft ( Id-mil Irnnth ................................... 30 ft Arrn, upper plnne ............... IM.fl A rrn, lower plnne ............................... 170.8 Total siip|Ktrtlnf( area ........................... 390 A rrn of rach nlleron ............................. 8.6 Totnl nllrron nrrn .......................... . 34.* I lorinnntal -t.iliiliwr ............................. M Vrrtlrnl stnhlltaer ............................... 18J Itucltler ......................................... l-'i o In. in in. In. 7 In. 9 In. ,. ft. ,. ft. V| ft. -I ft ,. ft. q. ft M|. ft. q. ft. Weights Welftht per .sq. ft -3i H>s. Wei(rht per h.p H-4 ! Nrt wrlfrht, machine empty 1,6218 Ihs. Weiirht, full load I.OI8 H. Performance Speed range 6i to 131.9 m.p.h. Climb 1,000 ft. per minute Thr Curtis., Model II-A Hydro aeroplane, which is rnted to hive a perd range of from 61 to 130 mile* per hour ,330 HP LIBERTY FLYING BOAT Jci.le of feet 10 a 14 I 234 SIXCLK MOTOKK1) A KK< )I>I ..\ M S An IIS -' I. anil other types of American flying boats mid seaplanes taking off in formation Curtiss Model HS-2-L Flying Boat In order to increase the amount of load carried, the MS I f. type of mncliine was given additional wing sur- f in .-uid tliii-. lr:mie the IIS v.' I.. The speed was not r%j In. ine Span - Lower Plane 64 ft. 121 ; fe, In. Depth of Wine rhoril 6 ft. 3%, In. dap U-twccn Wine* (front) 7 ft. 7% in. Cap ln-tween Wines (rear) 7 ft. 52% 2 In. _! r None Length of Machine- overall 40ft. Height of Machine overall 14 ft. 7'/ 4 In. Alible of Incidence t'pper Plane 5 1 /, degrees le of Incidence I.ower Plane 4 degrees Dihedral Angle 2 degrees ;ihack degrees ine CIIMC R. A. F. No. 6 Horizontal Stabilizer Angle of Incidence degrees Areas - I'pper 380.32 sq. ft. - I-ower 314.92 sq. ft. Ailerons (upper 62.88; lower 42.48) 105.36 sq. ft. Horizontal Stabilizer 54.8 sq. ft. Vertical Stabilizer 19.6 sq. ft. tor, (each J.'.s sq. ft.) 45.6 sq. ft. Rudder -''5 sq. . I Supporting Surface 8O0.6 sq. ft. g (weight carried per sq. ft. of support- 7.77 Ibi. ne surface) Loading (per r.h.p.) 18.84 Ibs. Weights \.t Weight Machine F.mpty 4,349 Ibs. Gross Weight Machine and Load 8.M3 Ibs. Useful I^ad 1^64 Ibs. Kurl 977 Ibs. Crew 360 Ibs. Useful loud . 527 Ibs. Total 1.864 Ibs. Performance Speed Maximum Horizontal Flight 91 miles per hour Speed Minimum Horizontal Flight 54 miles per hour ( limbing Speed 1,800 feet in 10 minutes Motor I.ilH-rty 1 -.'-Cylinder. Vee. Four-Stroke Cycle .... Water cooled Horse' Power (Rated) ' 330 Weight per rated Horse Power 3.55 Ibs. Bore and Stroke 5 In. x 7 In. Fuel Consumption per Hour 32 gals. Kurl Tank Capacity 152.8 gals. Oil Tank Capacity 8 gals. Fuel Consumption per Brake Horse Power per Hour 0.57 Ibs. Oil Consumption per Brake Horse Power per Hour 0.03 Ibs. Propeller Material Wood Pitch according to requirements of performance. Diameter according to requirements of performance. Direction of Rotation (viewed from pilot's seat) Clockwise Maximum Range At economic speed, about 575 miles. Front view of the HS-2-L equipped with a Liberty "IS" motor 236 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Curtiss Model HS-1, which was the forerunner of tin- The Curtiss Model HS-1 in flight, making a speed of 76 mile HS 2-L an nour The HS J-L, equipped with a Liberty motor. The wing spread of the HS 1-1- was in- creased to lift a greater load. A counterbalanced rudder was also added. This type of machine was used for patrol duty in this country and also as a training plane for the pilots of the H-16 and F 5-L boats. Side view of the HS 2-1.. It has been found that only one set of ailerons on the upper wing only is sufficient to handle the machine. The use of this boat for combat purposes is limited because of its unprotected rear portion. As a patrol scout it car- ried two bombs, beneath the lower wing, one on each side of the hull. The crew con- sists of two pilots and an observer in the front cockpit IOOHPCURTISSCKX FLYING BOAT ScaJ of feet Mn-Hn 237 238 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING CURTISS MODEL M. F. FLYING BOAT The Navy Department has em- ployed a great number of the M. F. Boats for coastal training work. Machine is well suited for marine sportsmen for it is com- paratively small and is easily handled. The boat is provided with either a Curtiss OX 5 100 h.p. engine or the new Kirkham K-6 150 h.p. six-cylinder vertical en- gine. The M. F. Boat is an im- provement in design over the Cur- tiss F Boat which found so much favor before the war stopped civilian flying Curtiss Model MF Flying Boat This machine is suitable for general and sporting use. It is an improved form of the F boat. General Dimensions Wing Span - Upper Plane . 9% in Wing Span Lower Plane 3 8 '%2 >' Depth of Wing Chord . > 6 ' Gap between Wings at Engine Section 6^ ft 4% 4 i Length of' Machine' overall ".'.'.'.'.'.'.'.'.'.'. 28 ft. W in. Height of Machine overall 11 ft. 9% to. Angle of Incidence " degrees Dihedral Angle, Lower Panels only 2 degrees Sweepback Xone Wing Curve U- . A. No. 1 Horizontal Stabilizer Angle of Incidence ... degrees Areas Wings Upper Wings Lower Ailerons (each 22.43 sq. ft Horizontal Stabilizer Vertical Stabilizer Elevators (each 15.165 sq. ft.) Rudder Total Supporting Surface Loading (weight carried per sq. ft. of support- ing surface) Loading (per r.h.p.) 187.54 sq. ft. 169.10 sq. ft. 44.86 sq. ft. 33.36 sq. ft. 15.74 sq. ft. 30.33 sq. ft. 20.42 sq. ft. 401.50 sq. ft. 6.05 Ibs. 24.32 Ibs. Weights Net Weight Machine Empty ............... 1.796 Ibs. Gross Weight Machine and Load ........... 2,432 Ibs. Useful Load ............................... ^6 Ibs. Fuel ............................. ^ lbs ' 22 ' 51bs - 3fi lbs ' Oil Water Pilot .......................... 16S lbs ' Passenger Miscellaneous Accessories Total 636.0 lbs. Performance Speed Maximum Horizontal Flight 69 miles per hour Speed Minimum Horizontal Flight 45 miles per hour Climbing Speed 5,000 feet in 27 minutes Motor Model OXX 8-Cylinder, Vee, Four-Stroke Water cooled Cycle Horse Power (Rated) at 1,400 r.p.m B Weight per rated Horse Power *-01 Bore and Stroke Fuel Consumption per Hour 1' Fuel Tank Capacity * g" ls - Oil Capacity Provided Crankcase Fuel Consumption per Brake Horse Power per Hour .... - 60 lbs ' Oil Consumption per Brake Horse Power per Hour ... - 030lbs - Propeller Material Wood Pitch according to requirements of performance. Diameter according to requirements of performance. Direction of Rotation (as view from pilot's seat) Clockwise Details Dual Control. Standard Equipment Tachometer, oil gauge, gasoln Maximum Range A', economic speed, about 325 miles. SINCil.K MOTOKK1) AKHOIM.AN KS .. I In Inn I, p l.ilxTty motored (iallnndet !)- lijjlit 1'iuiilxT -enplane The Gallaudet D-4 Light Bomber Seaplane Tin- Gallaudet D-J Light Bomber Seaplane uses a single KK> li.p. Liberty " Twelve " engine. Si \ir.il n-tiiu -incuts in detail have Ix-en incorporated in the IK w design, .., M ,l it is probable that the Gallaudet is now tin fastest sr.-iplnne ever built. Its maneuver- ability is exceptionally flexible, in spite of difficulties usually encountered in seaplane design. On Deeeinber IsJth a series .if tests of the !)- Sea- plane were carried out during a two-hour run over Narra- gansi It Hay liy the I'. S. Navy. The tests show the ma- chine to be capable of cruising at 78 miles an hour, while the engine turned at 1360 r.p.m. At this speed the fuel consumption was 16 gallons per hour, and the cruising radius 7.19 hours, in which time a distance of 561 miles could lie emered. General Specifications Span, upper plane 16 ft. 6 in. ClK.nl. Ix.th planes 7 ft In. t ween planes 7 ft. in. Total winjf area 6H sq. ft Wrijrht. iimchinr empty 3JWX) ll. of useful load ' 1.600 \\>-. Wri^ht. fully loaded i,4OO Ibs. Maximum sprrd I .'(i m.p.h. Slowest landing: 4.'. li m.p.h. Slowest p-taway 46.0 m.|>.h. Climb in two niinutr* J.UMI ft. Klyinjf rndiu.s at full power 3 hours The useful load is made up of the following: Water I l.i Ibs. Pilot and observer :O Ihs. Fuel and oil (UO Ibs. ( Irdnance 9.5 Ibs. Bombs 390 Ibs. Total 1600 ll.s. The fuselage is of streamline form, with a circular iec- tion bullet nose. Steel tuliinjf is employed in the frame- work. At the forward end the gunner's cockpit is located. A flexible searfed ring for mounting twin Lewis machine- guns is placed around the cockpit. A very wide are of fire is provided for the gunner, and an unobstructed view is obtained by both pilot and gunner. The engine is located aft of the pilot, between the up per and lower planes. It drives a ring surrounding the The GMlaudet D-4 leaving the water for a flight. Note the > i' k of the wings 240 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING fuselage, to which the four-bladed propeller is attached. This construction is unique in that it permits the ad- vantages of an enclosed fuselage usually employed in tractor machines, while the screw is placed in pusher position, permitting an advantageous placing of occupants and engine. Planes are flat in span and similar in plan, but ailerons are placed on the upper plane only. Planes have a mod- erate stagger and a pronounced sweepback. The center section of the upper plane contains a 38 gallon fuel tank with a supply pipe running straight down to the engine below it. A 75-gallon fuel tank is placed in the main float at the center of gravity. The fuel system employs twin wind- mill pumps with overflow return. Two radiators are located in the center section at either side of the gravity fuel tank. They are set into and con- form in outline to the wing section. Central pontoon or main float is built up of mahogany. It has 16 water-tight bulkheads or compartments. The two wing tip floats each have five compartments. GALLAUDET D-4 BOMBER The Giillaudet Bomber has a Lib- erty Engine of 400 h.p. driving a four-bladed pusher propeller. The machine is a two-seater with pilot and observer placed well forward. Fuse- lage finely streamlined and the plac- ing of the lower wings below the fuselage brings the center of thrust in a very desirable location. A maxi- mum speed of 126 m.p.h. and a climb of 2,100 feet in 2 minutes was re- corded in an official test flight The Gallaudet D-4 in flight over Narragansett Bay The Curtiss K-9 Seaplane, equipped with the Curtiss V-2 200 h.p. motor SIMiLK MOTOKK1) .\KHUIM..\NKS Typ< Thomas-Morse -S-5 Single-seater Seaplane Gener?! Dimensions I.cnjrtli Spread II. it-lit .'.'ft 'tin. .''. ft. ' in. !l ft. T in. Weight and Lift Data Total weight loaded 1500 Ibs. Arm lifting surface (including ailerons) JiO sq.ft. Loading per square font nf lifting surface 6.::> HIS. Keijuired horse power 105 eight i>f in.irhiiir loaded IMT h.p U.:i His. .Power Plant Type nf engine 100-h.p. Cinornr (air cooled rotary) n^'ine rrMiliitiniiK |iT liiinuti- Furl capacity, 'Mi (.'all. ins. sufficient for :{ liours' Hijfht at full power Oil capacity. ii..'i gallons, sufficient fur .'!'_. liours' flight at full poucr rn>|M-lliT t\ pi- 3 blade I'niprlliT diameter 8 ft. Propeller rcMilutions |>rr minute 1350 Chassis Ty I M .Twin |M>ntiMins and tall float Area Control Surfaces Ailerons: (two) 30 sq.ft. Klrv aturs ii gq. ft. The Thomas-Morsr S-i Seaplane about to make a lundlng. Motor: Gnome 100 h.p. f.S sq ft. Horixontal stahiltcer 16.H tq. ft. Vertical stabiliser 3.5 q. ft. Stick type control used. Performance speed 93 milrs ]HT hour speed M mile* per hour Climb in first trn minutes 6JOO ft. Navy M-2 Baby Seaplane Tin \l j S, -ipl.-uif d, M^'ii.'d by the Navy Department as 1. 1 hn. !>< t M used for sulimarine patrol work. It in tli<- sui ill. st s, ,-iplane ever built, and its size has gained for it thr ii.iini' of " niolrrule." It is easily set up and, eupyin^ -ii little space, can be stored aboard a sub- iiiariiu-. Tin- in.-u liiii.- is a tractor monoplane with twin floats. The |il uir has a span of 19 ft., a chord of -I ft., and n total w iii>r aren of only 72 square feet. The wing section is a modified K.A.F. 15. Overall length of machine 13 ft. Tin- floats .-ire 10 feet long and weigh 16 Ibs. each. I'lii \ are eoiistructed of sheet aluminum with welded seams. The interior of the floats is coated with glue and outside is not painted but coated with oil. F.xperi- ments have proven this practice to be most efficient in preventing corrosion. Floats have exceptional reserve buoyancy: with machine at rest on the water it i-. ini possible to overturn machine by standing on the wings near the tips or by standing on the rear of the fuselage. The engine is a S cylinder Ijiwrence 60 h.p. air cooled engine, driving a 6 ft. 6 in. propeller with a 5 ft. pitch. 12 gallons of gasoline and I gallon of oil are carried, sufficient for .' hours' flight. Fully loaded with pilot and fuel the complete machine weighs but .ion pounds. The maximum speed is about 100 m.p.h., and the low s|>eed is .'>(> m.p.h. The Curtiss R- twin pontoon rap). in.- equipped with a C'urtivs -I lip. motor THE FRENCH FB.A HISWO-SUIZA MOWED FLYING BOAT Sc.l. of ft Mclaughlin 242 SIN(;i,K MOTOMK1) AKK01M.AM - TIli- I '. B \. 11} in,; boat, lln t>pe nf liu.-it u.i^ useil extensively fur over-water lifililiii); In the al- lies, iinil lias proved MT\ sitisfac- lurx . The F. B. A. Flying Boat This boat, equipped with Gnome . Clcrget or niorr often Ilispaiio-Sui/a en-m. s. In- pro\ ed In !>< fast anil .l! suited fur lii-li speed coastal Hying. All the Allii-s. lint more p:irtinil;irly Franc.- and Italy, largely used the FBA !>(> it-, fur en er water fighting, and much good work has IHTII dune with it. General Specifications Spin, upp,-r plain- 47ft. 614 in. Span, lower plane 3i ft. 8-Tf, In. Clniril, upper plain- 6 ft. {, In. Clinril. lower plane iff. :J in. Cap between planes 5 ft. 9%;, in. Length overall 33 ft. :,,; in. t overall 10 ft. 8U, in. Net weight, machine empty 150O Ihs. iiross weight, machine and load 1600 Ibs. Knjrine, Ilispano Suiza 150 h.p. Propeller, iliameter ft ft. 6 in. Speed ranjre 99-45 m.p.h. ('limbing speed 3300 ft. per min. Main Planes Main planes are not staggered and have no sweephack nor dihedral. Fnd.s are raked at a 13 angle. In, i 1, nee angle of upper and lower planes, 3. L'pper plane is in three Dictions; lower plane also in :hree sections. 1'pjx-r and lower center wing panels are 7 ft. 8 :t s in. long. I'pper outer panels 19 ft. 10% in. ong; lower outer panels \'t ft. () in. Centers of inner interplane struts located 8 ft. 9 3/16 n. to either .side of the centerline of the aeroplane; inter nediate struts centered 5 ft. -.' 13/16 in. from inner struts; niter struts centered 6 ft. 8 in. from intermediate struts. Slanting struts carrying the overhang of the upper wing lave their upper ends centered 5 ft. 1 1 in. from outer truts. This leaves a 2 ft. 7 1/16 in. overhang at each ring-tip. Overhang on the lower wing. 2 ft. 73/16 in. Chord of the upper plane. 6 ft. 2~' s in. Front wing warn centered 7~x '" from leading edge; beams centered ! ft. II 7 '16 in. apart. Distance from center of rear icam to rear of trailing edge, 2 ft. 7 916 in. Chord of the lower plane, 5 ft. 3 in. Beam spacing rom the leading edge is similar to that of the upper plane. Distance from the center of rear beam to tin- trailing edge. 1 ft. 7 7 16 in. Ailerons on the upper outer wing sections are 2 ft. 7 ! Hi in. wide and H ft. I i:> 1C, in. in spnn. For propeller clearance the upper plane is cut away for 9 ft. 10 :l s in.; from the lower plane a portion 4 ft .S'o in. wide is cut away. Hull Overall length of the hull, 30 ft. 2 I 16 in.; maximum width, at rear of cockpit, t ft. 33/16 in. The planing step on the bottom of the hull occurs 10 ft. (>>* in. from the nose. The nose extends 8 ft. 6-% in. forward of the leading edge of the wings. Bracing rabies run from the nose to the tops of forward intermediate interplane struts. Provisions are made for carrying a pilot and passenger seated side-by-side in the rear cockpit, and a passenger or gunner in a cockpit forward in the hull. Wing-tip floats arc placed directly below the outer hi- terplanc wing struts. Empennage The empannage or tail group is supported by a set of .struts from the upturned termination of the hull. The horizontal stabilizer is set at slight positive angle. It is semi-oval in outline, its front edge located it ft. I I :< 16 in. from the trailing edge of the main planes. From front edge to trailing edge it measures 5 ft. 2 13/16 in. The elevator or tail flap consists of a single hinged surface 3 ft. 117 16 in. wide and 8 ft. In'^. in. in span. It is actuated by two pairs of small diameter tubular steel pylons at either side of the rudder. The rudder, of the balanced type, is mounted above the tail on a pivot situated I ft. 1 ' j in. forward of the tail flap. It extends |u RfNlUlT FLYING 60AT Mtr McLikujklin 245 246 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING The Georges Levy Type R Flying Boat, equipped with a 280 h.p. Renault Engine. Span, upper plane, 18.5 meters; lower, 12 meters; total length, 12.4 m.; overall height, 3.85 m. ; lifting surface, 68 sq. meters; stagger, 138 mm. .5; weight empty, 1450 kg.; useful load, 1000 kg.; speed, 145 km. per hour. Method of folding the wings of the Georges Levy Type R flying boat The Georges Levy two-seater flying boat " Alert," with a Hispano-Suiza engine. This is a lighter boat than the Type R. Both types have the folding wing feature. AUSTRIAN AGO TYPE 210 H.P. 5EA PURSUIT BIPLANE Scat. meters long; vidth at the step, .95 meters; maximum width, 1 meter; distance from bow to step, 8.45 meters; height of step, .16 meters. The shape of the body wtth the necessary lining .at the bow and because of a careful laying of the side and bottom plating approaches very much the shape of a solid body of fairly good streamline form. The wing floats are spaced 5 meters a"art. They are of streamline section, with flat sides, attached to the planes by means of one forward strut and two rear struts, with cross wire bracing be- tween the struts. The empennage or tail group is 2.38 meters in span, sustained in front by a vertical fin of very thin laminated wood, by two stays and two wire cables. Control wires of the rudder flaps or elevators run through the fin. The rudder is 1.40 meters high by .80 meters wide. The data -given out concerning the motor is as follows : " Motor: Hiero Flugmotor, Osterr; Ind. Werke Wars- chalowski, Eissler & Co.; A-G 6 cylinders; type HN1096. It develops 218 h.p. at 1400 revolutions per minute. Weight 314 kilograms. It is equipped with Bosch mag- netos and small starting magnetos. Propeller: 200 h.p.h. Hiero 6 cylinders; diameter, 2.72 meters; pitch, 2.25-2.40." Sketch showing the Austrian-Ago Sea-Pursuit Biplane " A-25 ' in flight SINCI.K MOTOKKI) A KU< >1M . A \ I - l.olui.-r l-'ljinjr Moat lc:t\ inp for a flight. Steel tiil.irij: plai ~ ,ui ii.i|x.rlaiil part in Hi. .oust ruction of this machine The Lohner Flying Boat This is an enlarged machine of the Lohnrr type, retain- ing tin- \' which is typical of the Lohner aeroplanes. There .in- six steel struts on either side and, two by two, .ire connected in transverse pl.-ines with steel tubes of Hi mm. outside diameter. The distance between two struts in the direction of the brace is 1.30 meters, and in the direction of Ihe spar 2.17 meters. General Dimensions Sp.m, upper plane 9.70 meters Sp.ni. lower plane 7.3) mrtrrs < hcinl. upper pi. me 2.70 meter* < linril, lower pliinr 2.M mrtrrs Mull. iii.-i\iiiiiiiii length li.iO mrtrrs Hiniili carrying capacity 400 kg. Motor, \n-tro Dataller soo h.p. Iii form the ailerons .in- tr.-ipcxoidal, like that of the It.-ili in I.olmcr machines. Length of ailerons, .S.17 me- mi an width. .!>() meters. Dinii iiMons of the empennage or tail group: Length of horizontal .stabilizer or tail-plane, 4.74 meters; width, ni-tiTs. Length of tail-flaps or elevators, 4.71 me ters; width, O.87 meters. The vertical rudder differs from that of the old 1 ohm r machines in that there is small balancing area forward of the pivot. The principal dimensions of the hull are: Maximum width, 1.50 meters; maximum length, li.SO meters; maxi- mum height. l.iO meters; step, .25 meters. The body has two seats side by side and one in front, upon which is mounted a machine-gun arranged to be movable and fired in any direction. Beside the pilot, next to tin- observer, there is also a machine-gun arranged on a movable tube inside the casing. The outside tube is the only additional piece the machine contains. The turret is armored. No bomb-dropping d< have been located. There are two vertical pieces of wood, with a circular profile notch fastened to the floats under the wings. It may be that these are used to drop large bombs, but no discovery li i* been made which would The winn float used on the " K-301," an Austrian S-seatrr flying boat of the l-ohnrr typr 250 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A close up view of a German flying boat, showing some new features of construction. Steel tubing is used extensively. The wing top floats are also of unusual design show how they are secured in them. Several hooks for small bombs were found. The lateral or wing-floats, instead of being hemispher- ical in shape, have a bow with good streamlines, which plow on the water surface like the prow of a ship. The accompanying drawing shows their general outlines. Each is 88 cm. wide and 181 cm. long. The engine, an Austro-Daimler, lias 12 cylinders a ranged in a V. It is rated at 300 h.p. CIIAl'TKK IV AEROPLANE AND SEAPLANE ENGINEERING Bv < OMMANUEK H. ('. UK inn s I > \ Tin- problem confronting tin Navy was largely detcr- inilii-il ;it tin- time tin- I'nitcd States entered thr w:ir by tin fact tli:it tin operations uf tin- (iiTinari and Au-.tn.in Hi ets I, i.l lii i-ii riiliu-iil |iritn-i|i.-ill\ to minor ranis fnun tin- Heel bases ,-it Kill and I'ola. ami tin only real sea- going operations comprised the activity of subnmriin I, Tin- work uf tin- si-a|il:iin s. tlicrcforc. was prim mlv reduced to that uf cooperation with the fleet in reducing the submarine menace. This naturally led to the estab- lishment of coastal .stations in France. Italy. F.ngland. Scotland and Inland. In these operations it was pos-i blc to operate seaplanes from shore banes in practically every CMC, ami the development of work with the fleet U-c.-ime a minor consideration. -mi- of the seaplane bases, however, werr sufficiently clnse tu enemy territory to \w within raiding distance of enemy planes of both land and water tyjK's. and it Ix-canic necessary for the Navy to extend its activities to the use of land planes for the protection of seaplane bases, while naval aviators also participated in big bombing raids on (iiriimn and Austrian territory. I refer to these matters in this grncrnl way, not to de- scribe tin activities, but to show that in naval work both land and water planes were used, and why the Xavy prob- lem was in general restricted to opi ration from shore bases rather than operation from ships. Activities, how- ever, were not confined to shore bases in Kurope. Sta- tions were established on the Atlantic const, principally for the purpose of submarine patrol and for convoy work from the principal ports from whieh our troops and sup- plies were sent abroad. Type* of Planes Developed The work of seaplanes abroad was that of submarine patrol and convoy work, and this having been determined on. all efforts were made to obtain the most suitable seaplanes for the service. The principal work was done with two tv|N-s of seaplanes, namely, the IIS-v! tin- sin- notored plane develo|x-d from the IIS-1 and the H-lfi. a copy of the Knglish seaplane of the same type il> v eloped as a result of Commander 1'orte's cx|>cricnce with tin- original America and subsequent types devel- oped therefrom. Finally, the F-.'i-I. type was developed from F.nglish designs for manufacture in this country by the Naval Aircraft Factory at Philadelphia. The ||> and the H-lfi have proved well suited to the work re- quired, but the F-5-L did not enter production early enough to get into active service before the armistice was red. The Navy did not attempt to develop land plane types. but accepted and used those which had been developed 2.-. I nnd produced for tin Army, adopting for this purposi iirlish llandley-Page. the Italian Caproni. and the Army Dll I and DM In order that pilots should be trained for this s. r\ n it was necessary to adopt training planes, and for this purpose the \avy developed and used the Curtiss \ the H ti nnd the |{ :i. the Aeromarine and Hoeing sea- planes, and the F-boat. and also i \perimeiiti d with n number of miscellaneous types, such as the (iiiome scouts both biplane and triplanc of Curtiss and Thomas man- ufacture and the (iallaudet \)-.'>. The most successful of these training planes was the N-!i, particularly after the original float had Ix-en modified and Inter on after the substitution of the Hispano 13O-li.p. engine for the O.XX loo-h.p. engine. This plane was a biplane tractor with a single center float, having wing tip balancing floats. It was remarkably strong and could perform practically all sorts of maneuvers. Although in training work it was frequently wrecked, then- were remarkably few deaths resulting. This I attribute to its moderate s|>ccd. great strength of construction and tractor arrangement, which made it suitable for training purposes. As soon as it was determined that seaplanes of the flying-boat type were to IM- used in service it became nee essary to provide preliminary training in a type of sea- plane which more nearly represented the conditions of operation of the big boats. For this purpose the F-boat originally developed by Curtiss for sporting and for naval use was modified and adapted to instruction purposes. I shall later on describe and illustrate the principal types referred to. So far as the aerodynamical and mechanical features of construction are concerned, seaplanes differ very little from airplanes, the principal difference being the use of the landing gear suited to operation from the surface of the water instead of from the land. The proportions are. naturally, somewhat different, and the performance is different, primarily, because of the great inertia due to the increased weight involved in the seaplane construc- tion. But bearing this in mind, the details of construc- tion of seaplanes are substantially the same as those used in airplanes. Factors Affecting Performance It will now be of interest to consider the principal factors which affect performance, ns it is necessary to understand these completely to develop a design which shall perform according to the requirements of tin service intended. For the purpose of illust rating the factors involved I have prepared a set of performance curves, which I believe will give a clear insight into this phase 252 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING of the problem. The complete calculation of the curves shown is given in the Appendix, together with the formu- las involved in the computations. The performance in power flight is determined by t horsepower required and the horsepower available, and, of course, the latter must always exceed the former ( power flight is not attainable. In determining the powei required there are two prin- cipal factors involved. The first factor is that of the horsepower required to propel the planes with their load in flight. This horsepower I term the plane's e.h.p. determine it, it is necessary to know the form and dis position of the wing surfaces used, as well as the aero- dynamic characteristics of the wing section employed The lifting power of the wing depends. on the area and the square of the speed of advance, and its resistance is also in proportion to the area and the square of the speed of advance, the speed of advance being the speed relative to the air itself and not the speed over the ground. The lift of an airplane surface and its resistance to advance are determined by the lift and drift factors, which vary with the type of section used and also with the 'angle of attack at which the surface is presented to the relative stream of air. It has been found by ex- periment that these factors are influenced by the propor- tion and arrangement of the surfaces, the best results being attained with what is known as the monoplane surface. Performance is improved by increasing the dimension of the wings in the lateral sense, over that of the fore- and-aft dimension. The ratio of these two dimensions is called the aspect ratio. As the aspect ratio is in- creased, it is found that the efficiency is improved indefi- nitely. But after an aspect ratio of 8 or 10 is attained the improvement in efficiency becomes less and less, and, practically, is not worth going after, because the dimen- sions become unwieldy and the gain in lifting power and efficiency may be more than wiped out, due to the in- creased weight and resistance of the structure required in employing it. It is largely on account of this diffi- culty that the biplane and the triplane have been used where large lifting power is required, even though in the latter cases the efficiency of the surfaces is reduced because of interference of the air flow, which is found to depend upon the gap ratio. By this is meant the ratio of the distance between superposed planes to the chord length, or fore-and-aft dimension of the wings. Where the leading edge of the upper plane is forward of the leading edge of the lower plane the efficiency is improved over that where one plane is immediately above the other, and conversely. This arrangement is referred to as stagger and the condition of positive stagger, that is, with the upper wing forward of the lower wing, is generally adopted with the view of improving efficiency. There are limits to its usefulness because of the obliquity of the trussing involved. Stagger may be adopted for various reasons, such as correcting the balance of an airplane in which the actual location of the center of gravity does not conform to that originally contemplated, or in order to improve the view of the pilot or observer, particularly if the latter is also a gunner. The efficiency is improved if the upper plane has a greater lateral dimension than the lower plane. This dis- position is known as overhang. There are limits to the extent to which this can be employed, on account of the structural difficulties involved. In the normal type of construction, the front and rear edges of the wings are parallel, although it is found that tapering the wings to a smaller fore-and-aft dimension at the wing tip improves efficiency. This arrangement is not satisfactory from a manufacturing point of view, as it involves different sized ribs at every station in the wings. All the above considerations have to be taken into account in determining the form and proportion of the wing surfaces. Another factor is very important, that is the travel of the center of pressure on the wing surfaces. It is found that where wings have a cambered surface which is usual in airplane construction because of the superior lifting power the movement of the center of pressure is such as to cause longitudinal instability. Various devices have to be employed to overcome this. The most satisfactory and usual method is to employ an auxilliary surface at the tail of the airplane called the horizontal stabilizer, and the best conditions for stability are found when this rear surface has a smaller angle of attack than the wing surfaces themselves. This difference of angle between the wings and tin- horizontal stabilizer is termed " longitudinal dihedral." The stiffness or steadiness of an airplane in flight de- pends on the area, proportion, section and angle of tin- rear surface. Where great stift'ness is desired, this rear surface may even assume the proportions of a second set of lifting surfaces which may be of monoplane or biplane arrangement, usually of smaller dimensions than the main 400 300 oj I CO 200 100 80 70 ^60 050 40 S 20 10 ^ ^ ~N 3> s J& ROf ELLE V -ICIE toy ;URV ; / DUR/ J\ *8 / L / \ / / / . 2 3 4 5 6 7 8 9 10 Typical Motor Characteristic and Propeller Efficiency ("urv< .\KK01M..\\K AM) SEAPLANE K. Mil \KKKI\c. planes. Where the rear surfaces are increased to ncarlv tin- proportions of tin- forward surfaces, the tnndciu biplane arrangement is approached. For military purposes ami for combating rough air conditions it is foiiml ilrsjralili- to lia\r initial loiigitudi ii ii stability, lint it is undesirable to have tins in , hiijli decree on a military plain- in wliicli steadiness mav I* essential to tin- propi-r operation of a gun or of a luimli dropping device. If (In r. ar surface were completely ti\l in nil! i, in In the forward surface it would be possi- l>lr to proceed in liori/ontal flight at our definite only for tin- load carried, and ascending or desi ending could he accomplished only by increasing or di --re-ism ; the power, or 1>\ de, Teasing or in. Teasing (he Jnad. These methods of eontrol are not sufficient lv accurate or active, and it is nmeh more satisfactory to use additional sur- known a> eh -valors, appended to the rear margin of the hori/.ontal stal ili/.cr. which by modifying the of the stabilizer make it possible to proceed in horizontal flight at any speed from the minimum to the maximum Ihiii;; speid. or to i-anse the plane to rise or descend. In iirpiains. in order to get the maximum of r vcring ahility. the hori/.ontal stabilizer is reduced to a \rry small area: or. e\eii. in some cases, is completely d with, all being merged in the elevator. In the original Wright machine lateral balance was maintain. -d hy warping the wings, but this ir.'!:cd i unfavorable to strength in Inrp- structures. ai:d t.'ie use of ailerons for this purpose I. as n w h.-comc ; :i--rnl. In flight, airplanes are not always operatic! so that the trajectory conforms to the axis of the airp! -lie, par- ticularly when turning or when encountering side g :sts, As a consequence, unless what is known as the keel siiriace of the airplane is distributed equally above and In-low tin center of gravity, there is a tendency for the airplane to roll one way or the other, depending upon the location of the center of gravity relative to tlie center of lateral pn ssiire. To compensate for this cti'cct. or to provide lateral stiffness under such conditions, it is usual tn provide a moderate amount of what is known as lateral dihedral: that is. the winir, tips are higher than the center iiortion of the wings; or else skid tins are placed i:n:;: lintch under or above tin- upper wings. These in gen- ral have the same effect as lateral dihedral. Hy modify- ing this arrangement the amount of lateral stability can be controlled to any desired degree. Again for mili- irv purposes it is desirable to have initial lateral sta- lility. but not to such a degree as to interfere with con- rol! ability of lateral balance. Directional stability is also affected by the lo.-ati-n of he center of side pressure, depending upon its location fore-and-aft of tile center of gravity. It is essential for !y (light that the center of lateral pressure at small ngles of skew should not pass forward of the center >f gravity. To accomplish this it is usually necessary to nstall a vertical stabilizer at the tail of the airplane. It s again desirable to have initial directional stability. \nd again, in a military plane, it is undesirable to have his to such a degree as to interfere with control of lirection. As the airplane is symmetrical relative to the vertical fore-and-aft plane, it is unnecessary to provide my equivalent of the dihedral effect, and it is only n-ees- ary to append a rudder to the vertical stabiliser in order 10 JO M 40 M 80 70 M 00 100 10 20 30 tO 80 00 TO HO W 100 110 I'M 130 110 I lorsrpower Curves of Ihp KAKtf Kiplnnr to control direction. In some planes, where extreme ma- u< uveral ility is desired. Uie rudder itself, in its neutral position, performs the functions of a vertical stabilizer as well na that of a rudder, and no vertical fixed surface is used. Location of Powerplant and Crew 1 1 iv in:: given due consideration to the influence of the proportion, arrangement anil dispositio-i of the main siip- porting and control surfaces, it is m-x' n -n ss.-.rv to eon sidcr the service intended and the location of (he power- plant and the crew. The possible arrangements arc al- most infinite, but in general it is desirable to locate the pilot centrally where he will have a proper view to enable him to handle the airplane to the greatest advantage, and this is particularly necessary in the combat plane. It is also essential that the gunner shall have an large and unobstructed a view as practicable, and that with the gun positions selected he shall IK- able to cover his are of fire and as much of the surrounding sphere as is prac- ticable, in order that there shall Ix- no dead spots from which the enemy may approach without his being able to return the fire. This sometimes requires that the pilot himself sh ill be able to operate guns firing dead-ahead, or that additional gunners shall Ix- placed so that they can cover area of fire not possible for the others to cover. In bombing planes and. in particular, in night bombing ones, this requirement is of less importance, and the requirement that the lx>mh dropper shall have a pro|XT view for the operation of the bomb sights become* of prime iin|tortancc. In airplanes di -signed for long-distance flights or for 254 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING bombing, it becomes necessary to have great power avail- able, and this requirement has led to the adoption of mul- tiple unit powerplants. Two, three, and as many as five powerplants have been successfully used for this pur- pose. The multiple-engine plane has the advantage that in case of damage to one powerplant it is usually possible to continue flight with those remaining; or, if still too heavily loaded to accomplish this, it is possible to glide for a long distance and thereby select a more favorable landing place, and often to avoid landing on enemy terri- tory. All these and many other considerations enter into the disposition and arrangement of the powerplant and fuse- lages, and these arrangements themselves have an influ- ence on the performance of the wing surfaces because of interferences involved. By winging out the powerplants a more favorable load distribution is imposed on the airplane structure and ad- vantage is taken of this feature in designing the wing trussing. The effects of interferences and of the dispo- sition and proportion of the wings or bodies and auxil- iary surfaces are so complex that unless data are already available from similar designs, it is very desirable that the resistance and lifting power of the complete design should be determined from wind-tunnel tests of a model carefully constructed to scale in every detail. Such model test is usually deferred until the design has approached some definite form after preliminary estimates have shown that it is capable of approaching the performance desired. Form and Proportion of Wings In preliminary estimates the influence of the form and proportion of the wings is carefully estimated, and from these estimates a fairly accurate approximation of the horsepower required for the planes is derived. To arrive at the total horsepower required, it is next necessary to consider the horsepower required to overcome the head resistance. In order to do so, it is necessary to have accurate knowledge of the resistance of all elements of the airplane structure exclusive of the wings, which are exposed to the action of the wind in flight. To reduce the resistance of these elements to a mini- mum, streamline forms are adopted wherever practicable, and even the truss wiring is made up of streamline form; or, if this is not found practicable these wires are cov- ered with false streamline covers of wood or metal. It is found that the reduction in resistance more than com- pensates for the additional weight involved in applying these false covers. The resistance of the fuselages, radiators, engines, tail control surfaces, elevator rudder, aileron horns and all other elements is computed in detail, and account is also taken of the obliquity of these elements to the flow of the air. Such obliquity is found to exert an important influence on their action. For preliminary estimates, it is customary to determine the resistance of these elements for the position assumed by them at some speed inter- mediate to the low flying speed and to the high speed attainable with full power, and then to assume that the resistance of these elements is proportional to the square of the speed for speeds above and below the intermediate speeds selected. This is most handily done by assuming that the resistance of these elements is represented by a flat surface exposed normal to the wind, which would have the same resistance as the aggregate of these ele- ments. This supposititious surface is what is referred to when we speak of the " surface of equivalent head re- sistance." In the example which I have chosen to illus- trate, " the equivalent head resistance " is assumed to be 20 sq. ft., and the horsepower required to drive this head resistance through the air is indicated on the curve de- noted head resistance horsepower. By compounding the ordinates of this curve with the ordinates of the plane's e.h.p. curve we derive the total e.h.p. required curve. We have next to determine the total brake horsepower available in order to determine the performance of the airplane. To determine this curve, we must first know the full-throttle characteristic of the engines to be used. This characteristic is indicated in the example showing the brake horsepower available at different speeds. The next thing to be determined, and the one having a most important influence on the performance of the T|T Tp 1 1 1 1 1 ttltolMHtMIM Chart for Determining the Dimensions of Propellers airplane, is the propeller characteristic. To date the progress in propeller design has been far from satis- factory, and although good results have been obtained, the best results possible have seldom been approached. In the selection of the propeller, one of the first considera- tions is to determine what feature of performance is most important, for it is necessary to select the proper dimensions with a view to gaining the best results for the service intended. For instance, if high speed is of greatest importance, the propeller to be selected will differ materially from that which would be required if great climbing power is desired, because the greatest climbing power will be attained at a speed much lower than the maximum rate. Or, it may be a question of selecting! a propeller which will give the greatest efficiency at cruis- ing speed, and this propeller will usually differ from that selected in either of the preceding cases. In some case* it may be desirable to select a propeller which will give the best all-round performance rather than for a par- ticular condition. In seaplane work a problem arises which is not found in the land airplanes. This problem is that of obtaining AI.K01M.AM. AM) SKAIM.ANK K.\<; I NKI .]{ 1 \ i . tlir crc.-itcst reserve of |mi r to n\ i rcoiue the resistance of tin- Hn.-it system, because it is desirable to have the _TC at. st possible reserve ti> accelerate rapidly on the watrr. so that the ^i-t away may In- made in rough water with the greatest possible rapidity, thereby reducing the uinislimciit which tin- sraplan.- suffers under siu-li <-on litions. I-'or a licavily loaded seaplane this consideration nay IK- of \ ital importance. Efficiency of the Propeller It must he understood that the efficiency of an airplane propeller is absolutely depeiident upon its speed of ad- vanee through the air. as is also the power which the impeller alisorhs in flight, the result being that CM-II liou^li the full throttle is used the engine cannot make its full revolutions until a good flying speed is attain., I. with the consequence that full power of the motor cannot :ie realized until flying speed is attained. The efficiency of a propeller is dependent upon n func- tion of the velocity and the number of revolutions and tin diameter of the propeller represented by the frac- y ion - The efficiency, the torque and the thrust, the lorscpower absorbed and the horsepower delivered are 'unctions of this quantity, in which velocity, the number >f revolutions and the diameter must be expressed in lie same units. 'flu influence of this factor is indicated on the pro- icller ellicii in -\ curve based on the values of the fraction . When this fraction equals 0.2 the efficiency of the ND impeller indicated in the example is only 37.5 per cent. The maximum efficiency is attained when the value of his fraction is 0.59. the maximum efficiency indicated n this case being 73.2 per cent. In the example chosen I have used a Durand propeller the characteristics of which have been determined >v wind tunnel tests, as reported in report No. H of the .irocei diiins of the National Advisory Committee for Veroimutics 101-1. To derive the dimensions for this propeller I have issuiued that it is desired to attain the best results at 80 niles per hr. with a I.ilk-rty engine operating at 1600 .p.m. and developing 380 b.h.p.. as shown by the motor haractcristic. In Professor Durand's report he has idopted KifTel's logarithmetic chart, and I shall now indi- ate how the diameter of the propeller is determined. On the chart at a speed of 80 miles per hr. erect in ordinate equal to 380 h.p. taken from the scale >n the left side of the chart. From the top of this irdinati next draw an oblique line parallel to the line ndicatini; the speed, and draw this line of such a length nd in such a direction ns to represent IfiOO r.p.m. on the scale starting with the origin at 12OO r.p.m. From :he extremity of this line m \t draw a line parallel to the ting the diameter scale, and taking the distance : rom this point to its intersection with the propeller haracteristic for the propeller No. N we find that this in.- intersects at the point (). Transferring the length nf this line to tin diameter scale and measuring in the firection in which it is necessary to draw this line to anake it intersect with the propeller's characteristic, we find that the proper dinmeter to use is (1. 4 ft., in.li, ,lin- an efficiency of <;.' ).. r nut Hy the us, nf tills ingenious chart it is possible to select a pmp< r diameter for a given set ul conditions by a simple graphical solution. The diameter now Ik-ing determined, it is next neces- sary to determine the perform. nice of the combined engine and propeller, and this is done as follows: On i transparent sheet of paper or tracing cloth a base line is drawn and. from any convenient point on this line, another is now drawn parallel to the scale of pro peller diameters and a distance is laid off representing the diameter of the propeller on that scale. I' mm the extremity of this line a new line is drawn parallel to the Chart for Determining the Performance of a IJIierty Knjrfne am) a Durand No. H Pro|>rllrr scale of revolutions per minute, and on this line is indi- cated the revolutions per minute of the powerplant. using the scale of r.p.m. for this purpose. From each point representing the different revolutions vertical or din iles arc now drawn, representing, according to tin- horsepower scale, the brake horsepower dc\eln|M-d by the engine at these revolutions, and through the points so determined a motor b.h.p. curve is drawn. Ni\t place this diagram on top of the logarithmetic diagram of the propeller, placing the origin on the base IIIK / on the base line of the logarithinetie diagram with the point .1 at the s|x-ed at which it is desired to determine the brake horsepower available. The pro peller efficiency, and from the latter the e.h.p. available, can now Ik- determined. This construction is based on the fact that the hone- power absorbed by the propeller and the horsepower TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING delivered by the engine must agree. Thus, for example, placing the point A at a speed of 30 miles per hr. it is found that the brake horsepower curve of the diagram intersects the propeller characteristic and the engine characteristic at a point B, indicating that the engine will make 1500 r.p.m. and develop 355 b.h.p. at this speed of advance. By drawing a vertical line through this point of inter- section of the two curves to the dotted characteristic of the same propeller, the e.h.p. developed by the propeller may be determined. This can also be determined by measuring the distance on the vertical line between the full line and dotted line representing the propeller char- acteristics. By transferring the length of this line to the scale for efficiency, the propeller efficiency can be determined. In this manner the brake horsepower available and the e.h.p. available have been determined and are shown on the horsepower curves on page 3. It will be seen that at 30 miles per hr. the engine can only turn the propeller at 1500 r.p.m., developing 555 b.h.p. Also, that at this speed the efficiency is only 35 per cent and only 12-1 e.h.p. is available, although the engine is developing 355 b.h.p. Determining Plane Performance Having now determined the e.h.p. available, we are ready to determine the performance of the aeroplane. It will be noted that the lowest speed indicated in power flight is 58.5 miles per hr. Thus these two points of per- formance are determined. The climbing power of the aeroplane with full power is determined by taking the difference of e.h.p. required and e.h.p. available at the particular speed at which the airplane is flown in the climb. This difference is greatest at the speed of 73 miles per hr. The climb is determined from the reserve e.h.p. available, which in this case is 76. Multiplying this e.h.p. by 33,000 and dividing by the weight of the airplane, assumed in the example to be 6500 lb., it is found that the initial climb should be 386 ft. per min. Further inspection of the curves shows that the mini- mum horsepower is required at a speed of 62 miles per hr. -It is at this speed that the airplanes should be flown to get the greatest endurance. If, however, it is desired to get the greatest range, the most favorable speed will be indicated by drawing a tangent from the origin to the e.h.p. required curve, as at this point the most favorable ratio is attained between velocity and horsepower required. In the example this speed is found to be higher than the speed for minimum power and is about 73 miles per hr. It will b; noted that the tangent to the curve sub- stantially conforms to the curve over the range of speed from 70 to 76 miles per hr. If the endeavor is being made to cover the greatest possible distance, it would be desirable to select the higher of these two speeds, for the reason that at the higher speed the controls would be more effective; the flight would be steadier and would be accomplished in a shorter time. As the aeroplane proceeds its weight will be reduced because of the consumption of fuel, and with a plane of heavy carrying capacity this reduction of fuel at the end of a long flight will appreciably reduce the load and thereby decrease the horsepower required for flight. In the example chosen, I have indicated the horsepower required when all the fuel is used up, assuming a weight at this time of 1500 lb. In this condition the most efficient speed will again be indicated by a tangent to the origin, and in the example this speed is appreciably lower than that indicated for the full load condition, being anywhere from 55 to 60 miles per hr. At inter- mediate stages intermediate speeds will be found the best for the greatest range. This, therefore, indicates that in planning a long-distance flight due account should be given to this effect, as the radius of flight will be ap- preciably increased if proper account is taken of the in- fluence of change in weight. To be exact, the tangent should not be drawn to the e.h.p. required curve, but to a set of curves which can be derived from these curves indicating the fuel consumption at different speeds and at different loads. The determination of the fuel con- sumption curves is a simple matter, but it would take more time and space than I consider it desirable to give in this paper. I can state, however, that the favorable speeds for long-distance cruising are not appreciably affected by using these fuel consumption curves in pref- erence to the e.h.p. required curves. The computations made in deriving the curves showr have been based on the Liberty engine, using straight drive. If it were possible to have available the same power with the geared-down propeller, it would be pos- sible to greatly improve the propeller efficiency anc thereby to improve the performance of the airplane indi cated in the example. It is unfortunate that the geared down engine is not available for general use, as the per formance of practically every plane I know of usinj tin's engine in our country would be materially improve( y bv its use. An inspection of the - efficiency plot wil make this clear. I also consider it unfortunate tha in the development of the geared-down Liberty engine which have been produced, advantage has not been take] of the possibility of locating the propeller more centrall; in relation to the engine group, because of the advantage which would be gained in streamlining. This engine i extremely awkward to streamline in its present form. Design of Seaplane Floats I will now proceed to the consideration of some o the elements of design of seaplane floats. The require ments of seaplane floats, because of the nature of thei use, are necessarily conflicting, and the best that can b done is to make a compromise, bearing these in mind. The first requirement of a float is that it shall be set worthy. This requires that the form shall be properl proportioned to provide good initial stability and reserve of buoyancy. This is necessary to obtain a re serve of stability, as the seaplane must float withoJ capsizing in a sea-way and in strong winds. This r quirement in itself conflicts with airworthiness ad lightness and with the adoption of the best streamliJ form, which otherwise would be, in general, a form sir ilar to a dirigible. It must be strong, but this natural! conflicts with lightness. It must also have good plal AKKOl'I.ANK AM) SKAIM.ANK KN( . I M .KM I \ i , nil qualities. .Hid tlii-. reipiirem.nl conflicts with str. un nc form. Airworthiness requires that it should have ir iiiiniiiiiini resistance and interfere ill tin- I hli- decree with the otlliT characlerist ics of the seaplane. In order to dcu-lop tin- best form of hull, tin Vi\\ )r]>;irtinriit began experinn ills .it tin- Washington nmili 1 isin late in lull. These experiments wen initiated by apt. W. I. Chambers. I . S. V. with a \ ii -w to tin- si- of hydroplane IHadi-s. such as had been used li\ orlaiiini. anil to improving tin |)aninir <|imlitics of the ii-n existing types of floats. At that time the most sue iful float was that eonstriieted by (ileiin II. Curtiss. i\ iiiiT a simple l>o\ seel ion and a slid form profile. At le same time Burgess I,.,,] developril twin floats having single step, which had also pnn- -fid. One of the earliest experiments at tin- model liasin was i attempt to reduce the welted surface to a minimum by ic use of a semi-circular section in the form of a half- ilind.r whose ends were pointed like a projectile to diice the air and water resistance. It was fortunate lat this model was tried ainonir the first, for its trials once showed up a factor which later was discovered ) lie of the greatest importance, this factor bcinir suction, n- to downward curxcd surfaces when exposed to tin' intact of water at high speeds. It was nt once realized lat in the test of the floats due allowance sho lid br ade to repns.nl tin change in load carried by the float s the speed of the seaplane increased and the lift of it- wmijs hccamc an important factor, and all runs at ie model I'asin had In'en made taking account of this and tcrminini; for each particular speed the " corresponding; splaccmcnt " of the float. This was originally done by mnterwcighting the float so that the weight resting on < water represented that which would he the case fak- ir into account the auxiliary lifting power of the wings, i the latest form of apparatus for testing at tile basin lis compensation is automatically made by the use of i inclined vane submerged in the model basin, which, v mi-ails of a system of pulleys, exerts a lifting power Inch is proportional to the lifting power of the wiims : the speed at which the test is run. In the tests with the semi-cylindrical model above re- rred to. it was found, as anticipated, that the resistance t low and moderate spuds was less than that cxperi- >ith other models, lint as one half of the speed for away was approached, and therefore the float car- ed only thr. i quarters of the original load, it was found mt the resistance of this model instead of decreasing. icreased: and that the model, instead of pinning, as as expected, settled into the water and. finally, at the et-away speed, with no weight being carried by the float ut the float just in contact with the water, the influence ion was so great that this model, instead of skim- ing the surface, proceeded to envelope itself in water a drawn down so sharply by suction that its deck M flush with the surface of the water in the tank and h.ets of spray were lifted clear of the surface f the mod-. 1 ! basin. A the work progressed the models of every known uccessful type of float were tried in the model basin. nd data were collected as to the performance of these lodclv At the same time many exjx-rimental model* were tried, and when these showid imprint im ir existing types, full si/id floats , r. eonstriieted and tried out in actual flight. I' mm these trials it was found that tin i oiiditions indie.it> d in tin model li.isin wen duplicated ill practice with full size, and it uas set n that the model I asin tests fori! ins of predicting the pi rtorui un of full sl/.ei| |(. The steps of the Hurgess floats were ventilati d. and an investigation of this feature showed the value < tilation for the step type floats then in use. All sorts of bow forms were tried and were shown to r\ little influence on performance. The use of one. two. three and four steps wns tried, and the indn i dons were that there \\.-is little, if any. advantage to IM- gained by the use of more than two. The introduction of the V bottom showed promise of improienn nt. but it was early found that a V-lftittom at the how was invariably associated with large i|iianti- : spray which would flow over the planes, and also. a cross wind would make the navigation of the senpl-ines very uncomfortable. It was found by making the lines hollow at the bow that this spray could he held down close to the wait r. and ill some later designs this hollowinss was also introduced nt the step, apparently with tune tieial results. After much experimenting it finally IM- .-.ime apparent that the best form of hull wns that em lodying the single veiitilnted step, in which the after bottom rose at an angle of approximately H deg. to the bottom just forward of the step. The reasons for this ore about as follows: With this type of float sufficient buoy- ancy can IM- provided abaft the step to eliminate the in c. s sity of tail floats for stability. It was also found that by ventilating the step the water flowing under the forward bottom flowed over the step in the form of an im.rt.d waterfall and that the contact of this inverted stri am moved further aft as the speed increased and i: in rilh paused 102030406060708090 100110120130140 Seaplane hortepower currm afloat and flylnit. 258 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING clear of the tail of the float just before planing was at- tained. At this point maximum resistance was encount- ered. After this point was passed the float proceeded to plane on the forward step, and because of the raised position of the tail of the float, it was then possible to vary the trim of the plane and change the angle of attack with- out again bringing the tail of the float into the water. Then progressively as the speed increased to flying speed the planing power of the portion forward of the step in- creased rapidly and the amount of wetted surface exposed to the action of the water was rapidly reduced, and the resistance of the float decreased, until finally at the get away the water resistance of the float was eliminated. The best results are obtained where the bottom of the float just forward of the step is substantially parallel to the axis of the seaplane. This portion of the bottom should have no curvature for a distance of several feet forward of the step. Attempts were made to curve up the portion abaft the step with a view to producing a better streamline form for the hull, but this curvature was invariably found to produce suction, retard planing, and in many cases to augment the resistance of the float to such a degree as to require an excessive reserve of horsepower in order to get away. There was one case where a flying boat was built with very moderate curvature abaft the step, but on account of this curvature in the tail was unable to leave the water with a single passenger. Even though it could get up to a speed where the step itself was clear of the water, the tail would still drag and could not be drawn out of the water. By slightly modifying the tail of the float so that the lines abaft the step were straight, this same flying boat with the same powerplant was able to get off the water with a pilot and passenger. One of the earliest floats tried at the model basin and built in full size was a twin float having a sharp V-bottom. The lines of this float conformed to the lines of a success- ful gunboat, and it was very pretty and clean in its action, but due to the influence of the curvature of the buttock lines at the stern, suction was present in this model and an airplane fitted with these floats, although able to get away with a pilot, was unable to get away with a pilot and passenger, there being insufficient reserve power to get over the hump. Until very recently it was considered that so many inches of beam were required for every 100 Ib. of weight carried by the float in order to attain planing, and this criterion has led to the adoption of the great beam found in the F-5 and H-16 and HS-2 models. But experiments with floats suited to carry 1000 Ib. each indicated that this model was remarkably satisfactory. The attempt was therefore made to enlarge this model in geometrical proportion to a 2000-lb. float, and the model basin results indicated that this could be satisfactorily done. Another model was made of a 2000-lb. float and behaved satis- factorily. This same model was expanded to a 6000-lb. float, which behaved even better than the original. The lines of the N-9 float, which has proved successful in our training program, were developed from the original 1000-lb. float, although this float had less beam than the original full-size float which was unsuccessful. As a re- sult of these trials, I now consider it to be conclusively established that once a satisfactory float is developed fol carrying a definite load under given conditions, the same design can be used for larger loads by merely expanding the original lines in the ratio of the cube root of the displacement ratios. In the design of the float for the NC-1 this principle was used and the model tested in the model basin, aH though only one-twelfth full size, gave data which indi- cated satisfactory performance. These data have been closely verified by the actual performance of the NC-lj though many designers were skeptical that this floaj could handle its load on so narrow a beam. This is nfl greater than that used in the F-5 ; the F-5 carries a load of only 13,000 as against over 22,000 Ib. carried bj| the NC-1. Attention is now invited to a series of curves showing the results of model basin tests on a number of different models. Results of Model Basin Tests Compared The dimensions of the' floats and the seaplanes thej represented were so different that to get a comparison it has been necessary to plot these results on non-diuieni sional scales. It will therefore be noted that the disj placement of the hull is plotted as a per cent of tha total displacement based on a per cent of the get-awal speed. The resistance of these floats is indicated by 9 tAPERIMENTAL MODEL BASIN AIRPLANE FLOAT TESTS MODEL NO. FOR -NAME H-12 20,55 AA.D. 20SO H-l 2<*1-A K-C-I 2081-B 2081-C 30 40 50 60 70 PER CENT OF GETAWAY SPEED Results of tests at model basin on a number of seaplane floats. plot of the ratio of the displacement to the resistance! also, based on the per cent of the get-away speed. Based on the plot of model No. 2022, which is that o$ a successful H-12 boat, I have plotted the resistance and the horsepower required to overcome this resistance for the sample seaplane, the horsepower curves of which I have already explained, and I shall return to those plots in a few minutes. Before doing so, however, I wish l<> invite your attention to the plots of models Nos. 2081-^ 2081-B and 208 1-C. You will note that the resistanc of No. 2081-A was nearly one-quarter of the displace ment at 40 per cent of the get-away speed ; that th resistance of No. 2081-B was reduced to nearly one-fift of the displacement at about 47 per cent of the get-awajj speed, and the resistance of No. 208 1-C was between oiic- fifth and one-sixth of the displacement at about 52 pel cent of the get-away speed. Also, the displacement il the latter case is less than in the preceding cases. AKKOIM.ANK AM) SKAIM.ANK KMJ I \ KKI{ 1 \ ( . J.V.i Tills change was brought aliout as follows: The original form of float had two -I. ps. with curvature in Hi. nii.ldlr step and a rank tip-curvature in tin- rear step. So. -.'iiM 15 represents this model with tin- rear step straightened, anil No. -.'I IS I (' represents this Mnat with straight lines for tin- liottom ahaft the tirsl st, p. It will rraililr In- si-i-n th.it tin- first modification was an im- provriurnt oicr tin- original, ami tin- s.-conil inoest of the argument. From a service point of view the deep V-bottom has many advantages; among them its remarkable shock-absorbing properties in taking care of bad landings, or in getting away and landing on a rough sea. The V-bottom also permit- landing across the wind without serious retardation and without danger of capsizing sideways. This type of hull appears to absorb the shock by penetration and reduces the loads imposed on the bottom planking and on the framing supporting this. Due to this feature there is no need of carrying shock absorbers between the floats and the rest of the plane structure, and the lightest possible construction can Iw adopted. In the longitudinal system of support the inner ply of planking is run athwartship and thereby constitutes a continuous system of ribs. This system is further reinforced by the outer planking run 45 deg. to the keel, which also acts as a continuous system of ribs, and these two systems transmit the water pressure as a distributed loading to the longitudinal members, which do not have their strength robbed by a series of notches. The lon- gitudinals are arranged so that they collect the dis- tributed load and concentrate it at points of support in athwartship bulkheads and these bulkheads in turn dis tribute the load to the keel, to the chine stringers, and to the deck planking. The keel itself is usually associated with a center longitudinal truss. Through these mem- bers the load is finally distributed to struts or directly to the wing structure. On a large scale this system is adopted in the construc- tion of the hull of the NCI which, although it embodies other features than those necessary to support the bot- tom planking, weighs only 600 Ib. while it carries a load of -J-MI.IH Ib. This hull has demonstrated ample strength in landing on and getting off an 8-ft. cross sea in practically dead air, where the landing and get away were both made under the hardest conditions. A controversy has existed for years as to the merits of the single float as compared with the twin float, but. based on the experience of our Navy with examples oi both types, I believe that the central float with wing tip balancing floats is decidedly the better arrangement. In '260 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING the central float system the loads can be concentrated on the point of support, whereas in the twin-float system the loads are usually concentrated in the center of the span and the wing structure has to be utilized to gain the necessary stiffness and necessarily has to be made heavier. In the center-float type if a single propeller is used it is located above the float and protected from the water, whereas in the twin-float type such propeller neces- sarily swings over the gap between the floats, which subjects it to punishment by spray and broken water. In landing a twin-float seaplane, unless botli floats arrive at the same time, the second float invariably strikes harder than the first, being slammed down on the water. Due to the greater lateral stiffness of the twin-float sys- tem, when getting off rough water the seaplane is forced to conform in its attitude to the form of the surface and wracks and lurches violently sideways unless going directly across the crest of the sea. In maneuvering in the air, also, the separation of the twin floats adds con- siderably to the inertia about the longitudinal axis and makes the action of the ailerons less effective. With twin floats, when taxi-ing across a strong side wind the lee float must have at least 100 per cent reserve buoyancy and this leads to greater weight than is necessary witli the single center-float providing the same stability. Appendix V 3 Kill', The tables appended give the calculations for the per- 10 20 1,000 8,000 O.Hi 1.28 formance curves of a seaplane with a biplane arrange- 30 27,000 4.32 ment of R. A. F. 6 wings and a head resistance of 20 40 64,000 10.34 sq. ft. In these calculations the following formulas were 50 125,000 20.00 usod : 60 216,000 34.60 70 343,000 55.00 80 572,000 82.00 K W TV T = W 4- -7-^ I'- = -r , EH~P - 90 729,000 110.50 /i 1\. S 375 100 1,000,000 KiO.OO 120 1,728,000 270.00 W Weight in pounds T = Thrust in pounds V = Velocity in miles per hour 8 = Wing surface in square feet *^. = Drift factor for biplane arrangement K U Lift factor for biplane arrangement EHP, WAV- T', AV % = 6500 l^ =M4g /W, \ / H ^2 \ EHP (w. ',) = I - 3 (ii rj = 1.73 T KJS F* r TV Flanes - EPIli r, EIIP, V, 1,030 0.301 21,600 147.0 151,300 404.0 404.0 147.0 234.0 122.5 532 0.595 10,900 104.5 55,700 148.5 2 148.5 104.5 86.0 87.0 474 0.861 7,550 87.0 41,200 110.0 4 110.0 87.0 68.5 72.5 516 1.085 5,990 77.5 40,000 106.7 g 106.7 77.5 61.5 64.5 575 1.309 618 1,512 4,960 4,300 70.5 40,500 65.7 40,600 108.0 108.2 8 10 108.0 108.2 70.5 65.7 62.4 58.8 62.5 54.8 684 1.708 3,800 61.7 42,200 112.2 12 112.2 61.7 65.0 51.5 833 1,848 3,520 59.5 49,500 132.0 14 132.0 59.5 76.3 49.6 1,160 1.911 3,400 58.5 67,900 181.0 16 181.0 58.5 104.6 48.8 K SV3 EIIP h = ^pp and is independent of the angle of attack. The float and having EHP for an H-12 seaplane weighing 6500 Ib. a get-away speed of 62 miles per hr. is given K S 0.06 and ~ 37o = 0.00016 below for varying percentages of the get-away speed. Angle of attack, deg. K x X 10,000 K X 10,000 K l/ K x W 0.62 4.3 6.3 6,500 2 0.65 8.5 12.2 6,500 4 0.88 12.3 13.7 6,500 6 1.20 15.5 12.6 6,500 8 1.65 18.7 11.3 6,500 10 2.06 21.6 10.5 6,500 12 2.55 24.4 9.5 6,500 14 3.30 26.4 7.8 6,500 16 4.85 27.3 5.6 6,500 Per cent of Get-away Speed r A< P er cent A.lb. A/R R RV EIIP 10 6.2 99.00 6,430 20 12.4 95.70 6,220 9.80 635 7,880 21.0 30 18.6 91.00 5.910 4.90 1,205 22,400 59.8 40 24.8 84.00 5,460 4.6.5 1,172 29,100 77.7 50 31.0 75.00 4,870 5.40 903 27,100 72.3 60 37.2 64.00 4,150 6.15 675 25,100 67.0 70 43.4 51.00 3,310 6.10 543 23,600 63.0 80 49.6 36.00 2,340 5.30 442 21,800 58.2 90 55.8 19.00 1,235 4.00 309 17,300 46.2 100 62.0 0.00 .\KHOIM..\\K AM) SK.MM.ANK ENGINEERING 261 I).\T\ <>\ on i i KI M rrPBfl "i I II INC BOAT* Wright. fnll> |,..,(l,- fs.-flll 1.1.111. Ml M.ixiiiiiiin speed, miles JUT hr. Miiiiniiiiii speed, mill-- |KT hr Initinl i-linili. ft II span. ft. -in II length, ft. -in II height, ft. in Chord, ft. -in. ' rra. s(|. ft Hull length, ft. -in. rryinj; a loail of .'l.'.Mi ML \in- .-, I., i, I ,,i ll> 1 II l', S. 1 10.900 13JOOU . ,%400 4,740 7,740 M 94 -i 44 46 47 61 i i',400 to 3,000 ill 10 min. 3,000 In 10 min. i lo min. < in '. min ; i o i" 94 13/16 103 9 1/4 IM 38 4 14/16 46 11. : 49 3 11/16 68 1 i/3i II 71/4 K * 4/8 18 9 1/4 6 3 4/39 1 49/64 8 I. 1 tat I.U.I :..'.. 34 3 3 II 7 > \t a speed of 1,7 miles |KT hr. with n load of .M;JI- II.. The Discussion CUT. \\". I. CnvMiim-: As to tin- most serviceable si-;i|>l:iin- type at present. I ran conceive of tin service abilitv of the following general iiutlinr: (I) One middle Hoat entirely riu-loscil. without cockpits. machinery or carpo capacity: .' i a short miilillc fuselage located above the middle flont. with engine, pusher propeller, cargo space .iiicl forward L;IIII mount: ( .'i 1 two whip fusclapcs. forming supports tor the tail, a la Caproni, each with engine propeller and rear pun mounts : i H two smaller whip floats for lialancinp ]>nrposi-s. not at the whip tips, but located under the tractor propellers of the wing fuse the tail planes comparatively near the main ones and n--' d so that they may he utilized, in a fixed position, to afford inherent stability on lonp steady tliphts and yet be capable of mobility in response to any demands for quick manciivcrinp. While I do not suggest any finality as to model or type of either powcrplant or rig of the plains. I do not hesitate to predict, however. that future modification ami improvement will depend .pon further improvement of the powcrplant than on any other factor. (Ireat improvements in tlii. part of the aircraft an due. and each decisive step will result in a modification of airplane types for each specific pur- !>,.*, OIIMIII WiniiiiT: Commander Richardson's figures for the performance of propellers arc based on tables de- Tom experiments with models. The trouble with tables ,,f this kind comes from the fact that it is most iilficult to determine the exact value of each of the fac- lors which play a part in the pro|M-llcr's efficiency. The re- made with several variable factors, so that the measurements secured really show the result of the sum if these variables. The exact value of each one is not ued. I am of the opinion that much closer cal- ulatioiis .an IH- had from a theoretical consideration of M lions that must take place in a propeller. Cotn- n.-ind. r Richardson tinds that a propeller '.i. t ft. in r. driven by a Liberty engine, turning at Minn r.p.m. and developing :fSO b.h.p.. in traveling forward at niles per hr.. would have an efficiency of i'.' p- r cent, or a loss of only SI per cent. I believe it an ! show n that the loss from slip alone, without con cllcr of !>. > ft. diameter consuming :isn h.p. while advancing HO miles per hr. I have made a rough calculation of the performance such a pn pellcr should give, based upon the propeller being considered merely as airfoils traveling in a spiral course. A prop. Ih r H. I ft. in diameter work- ing under the conditions stated would have a thrust of approximately !>.SO Ib. ; the slip would amount to M.I per cent of the total amount of air the projK-ller traveled through, and the efficiency of the angle of advance would be 80 |MT cent. The total efficiency would therefore Iw 0.65 x 0.80 or 52 per cent. Commander Richardson uses a method of calculating 262 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING the rate of climb of an aeroplane which seems of doubt- ful value. He makes no allowance, so far as I can see, for the extra loss in efficiency of a propeller when climb- ing. The thrust in climbing must be approximately equal to the thrust when flying at the same speed on a hori- zontal course plus the total weight of the machine multi- plied by the sine of the angle of climb. It is apparent that if the machine were to climb in a vertical course the propeller thrust would necessarily have to be equal to the entire load of the machine. On an inclined course the propeller would have to bear a proportion of the entire load plus the thrust necessary to give the machine the desired speed. When climbing, the propeller efficiency is especially low in small-diameter propellers, because on ac- count of the extra load imposed, the slip becomes ex- cessive. COMMANDER RICHARDSON: A great amount of theo- retical work has been done on propellers, taking it from all points of view, but in my opinion none of these meth- ods of analysis are as satisfactory as the wind-tunnel methods, because even the theoretical investigations re- quire the use of coefficients which must be developed from experience or practice. And I believe that when a propeller shows 59 per cent efficiency in a wind-tunnel test, where the quantities can be actually measured, that this is the real efficiency of the propeller in question un- der the conditions of the test, and no amount of mathe- matical or theoretical investigation will convince me to the contrary. The airplane horsepower required curve shows the horsepower required to propel the plant at any angle of attack, and this is relative to the air and re- gardless of the path of the plane. The horsepower avail- able depends on the characteristics of the powerplant, in- cluding the engine and propeller and, as I clearly dem- onstrated, the propeller efficiency is a function of the speed of advance or the quantity f'/ND. The curve of horsepower required, therefore, shows at any particular speed of advance of the airplane the actual horsepower effectively delivered by the propeller, and the difference between the power required to propel the plane and the actual power available is available for lifting. The brake horsepower required of course is much greater, but in the computation of the horsepower available the effects of the reduced speed in the climb are taken care of. The propeller chosen for the example was selected for the purpose of illustration and not because it was the most efficient possible. Both Eiffel's and Durand's experiments have shown that efficiencies as high as 80 per cent are entirely possible. I HAPTKK V NAVY DEPARTMENT AEROPLANE SPECIFICATIONS The general specification- of requirements issued by the Navy Department for use in connection with contracts. and the submission to it of new and undemoiistratcd de- s of aeroplanes, ire interesting as indicating broadly tin- state of the art from the standpoint of this arm of the (ioxcrmncnt. The s|>ccitications are comprehensive, and give clear evidence of ability and knowledge having been applied in the preparation of them. Although the requirements which are summarized be- low in ] irue part, may IM- modified in the case of com pleted aeroplanes available for demonstration, sufficient information is essential in any ex t-nt to permit reasonable verification of claims of performance and as to strength. No new project will he encouraged unless it promises a marked adx nice oxer planes in service or already under trial, (in -it consideration will be given to possibilities for immediate manufacture, facility of upkeep and rapid dismounting of engines, and reduction of general dimen- sions. (icneral arrangement plans, one-twelfth or onc-twcnty- fourtli full size, showing plan, side and front elevations. to be transmitted. The following are to be indicated: Over-all dimensions, and principal dimensions of por- tion- -hipped partly assembled; Gap. chord and stagger. Positions and angles relative to the propeller nr:is for the main and auxiliary surfaces and floats; ion of center of gravity of aeroplane for full load and light load as defined under Rules Governing Conduct of Trials; Position of center of buoyancy and corresponding wa- ter line of the float sxstem when at rest on the water with full load: Portion of axis of landing wheels relative to center of gravity for full load; .ranee of the pro|x-llcr: For tractor tyjx-s to be shown with the propeller axis horizontal; for pusher ty|M-s to IM- shown with the aeroplane in position at rest on the surface; Angle of attack at rest on the surface under full load ; Areas of main and auxiliary surfaces; Dihedral angle; sweep back; wash-out or permanent warp, if any. The detail plans called for are: Details of spars, showing full sixe of the spar section in icli bay; - 'ion of aerofoil, showing with dimensions the posi- tions of the spars and details of wing ribs; Details of wing .struts and drift struts, showing full sise the central cross-section-, and details of taper, if any ; I >. tnls of typical strut terminal fitting and wing spar titling, with anchorage to wing spar and to stagger, lift and landing wires; Details of hinge connection between wing panels; Details of aileron, elevator and rudder hinges and horns, and general construction plans of thisc surfaces; Details of float construction, including lines and a state- ment of reserve buoyancy. The required assembly plans are those showing: The arrangement of all control leads and types of fit- tings used with them; The installation of compass, instruments, armament or other special gear. Arrangement of wing wiring, including lift and land- ing wires, drift and stagger wires, and tabulated strengths; Landing gear and shock absorbers, size of wheels, tires. axles and struts ; Propeller proposed, including section and angles at sta- tions o.l ;>. O..SO. o. r.. o.0 and 0.90 of radius; Mounting and general installation of the engines, with oil and gas tanks, starting, air intake, exhaust, and all piping arrangement; Cowling and ventilation arrangements for engine and cooling -y-tem. giving complete specifications of radia- tors employed. These further data are asked for: Detailed tabulation of estimated weights, showing weights included in light load and full load with the cal- culation of the locution of the center of gravity vertically and horizontally for each of these conditions with refer ence to the front edge of the lower plane with the pro- (M'llcr axis horizontal ; Diagram showing loads on the principal members of the wing and body truss, including a tabulation of the characteristics of the principal members, their loads and stresses under the several conditions specified under Fac- tors of Safety ; Calculated performance chart, showing the curve of effective horsepower required, the propeller efficiency, and the effective horsepower available, all based on velocity of advance in miles JMT hour; also a curve for the engine employed, showing brake horsepower plotted against rev- olutions per minute; A statement of the type and principal characteristics of the engine proposed, together with oil and fuel eon- sumption per brake horsepower hour; 264 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING A statement of the performance with full load at sea level including: Weight, full load; useful load; maximum speed ; load in pounds per square foot of plane area, in- cluding ailerons; load in pounds per horsepower; climb in 10 minutes; tank capacities for fuel and oil; endur- ance at full power at sea level. The aeroplane must have construction permitting fa- cility of observation, inherent stability, ease of control and comfortable installation for the crew. The general specifications are to be construed to include Bureau of Construction and Repair and Bureau of Steam Engineering detail specifications in effect at the respective date. All materials and processes are to be in accordance with any such detail specifications; otherwise, in accord- ance with trade custom as approved by the inspector. It is stipulated the contractor shall provide all material, parts, articles, facilities, plans and data to conduct all trials. Non-metallic materials, such as dope, glue, var- nish and ply-wood, are supplied by firms on the approved list of the Bureau of Construction and Repair. Inspectors may reject peremptorily any inferior work- manship or material. The contractor has the right of appeal to the Department, whose decision is final. The contractor is obligated to furnish under the con- tract, without additional cost, such samples of material and information as to the quality thereof and manner of using same as may be required, together with any assist- ance necessary in testing or handling materials for the purpose of inspection or test. The passing as satisfactory of any particular part or piece of material by the inspector will not be held to relieve the contractor from any respon- sibility regarding faulty workmanship or material which may be subsequently discovered. As soon as work on the contract is started the contrac- tor is on request to prepare for approval a full-size model of the cockpits, showing the general arrangement and disposition of seats, safety belts, controls, instruments and accessories located therein. The object of this is to test the feel of the cockpit for roominess, convenience of control, suitability of location of -all parts and amount of view afforded. Engines, armament, instruments and accessories will be supplied by the contractor or by the Department, and be installed by the contractor in an approved manner and location. The engines, armament, instruments or other fittings, to be supplied to the contractor by the Department will be free of cost, but the contractor will be required to fit them in the machines at his own risk and expense, and be solely responsible for carrying out successfully the requirements of the specification. Alterations and substitutions will be permitted only upon the approval of the inspector in charge but wher- ever such alterations may affect the contract plans and specifications, the aerodynamic qualities, structural integ- rity, or military characteristics, such approval must be obtained from the Department through the inspector in charge. All changes approved by the bureaus or requested by them will in general be of two classes: First, those of immediate military importance or necessary for safety, which will be incorporated in all units at once, and new parts shipped after units already delivered, so that the stations may incorporate the changes; and, second, changes which are desirable but not so urgent as to war- rant interference with production. In case of the first three machines of a new type, all material of every description placed on or attached to the aeroplane is to be weighed, together witli all material of every description which, after being weighed and placed on or attached to the aeroplane, is removed ; and such weight and description of the part weighed in all cases reported to the inspector. Where material is assembled before being weighed, the center of gravity of such assembly is to be ascertained. The center of gravity of each part or group of parts en- tering into or attached to the aeroplane must be reported in relation to the front edge of the lower plane with pro- peller axis horizontal. Parts which are partially or completely assembled be- fore installation are photographed and prints supplied. In addition, photographs of the complete assembly are to be submitted, giving the maximum amount of detail in not less than four positions. PLANS AND DATA One set of general arrangement plans shall accompany each aeroplane for use in erection, together with a set of instructions for erection; also construction specifications of the aeroplane; specifications and statement of sources of supply of all wood, veneers, metals, forgings, stamp- ings, wire, cable, glue, fabric, dope, paint, varnish, tub- ing, pulleys, tanks, etc. ; description of practice followed in seasoning wood and heat-treating metal, finishing fabric. securing fabric, making wire and cable terminals, rust- proofing of steel parts, waterproofing of wood parts : and statement of the parts that have been brazed, welded or soldered. Landing Gear The landing gear must be of an approved design and construction. Location of the wheels shall be such as to prevent any undue " spinning " when landing down wind under conditions specified. Particular attention will be given to simplicity of design, reduction of head resistance, and the least weight consistent with the service intended. Staunchness of construction is required while disposing material to greatest advantage, transmitting loads by suitable fittings and fastenings into the principal members and through them to the structure as a whole, in order to obtain strength without excessive weight. If at the same time resilience can be obtained it will be an advantage. and shock absorbers may be employed if their introduc- tion involves improvement in performance. Streamline form is desirable but must not be permitted to affect sea- worthiness. Water-tight subdivision is required as well as suitable access and drainage for each compartment. Hulls hav- ing double bottoms to the step, are to have suitable drain- ing arrangements incorporated in this false work. Drain- plugs and handhole plates are required on tail and wing-tip floats as well as on main floats. Flying boat hulls are. provided with a hand bilge-pump and means for pumping out any compartment when the craft is adrift at sea. Double skin boats shall have cotton sheeting and marine NAVY DKI'AHTMKXT AKKOIM.AN K SI'K( 1 1 1C A 1 K >N s glue U-tween tin- plvs. Hulkhcads should In- utilized AS .strength incinlirrs :uul he reason. ihlv w all r tight for at least twelve hours. 'I'lir form "I tin liiittnin should be such as ID permit casv planini: Hilli longitudinal control. Tin Inrui slionlil :I|MI ! such is In rrilurr tlir shock of landing or of run ning .it high speed on lough water. Tin stahilitv when afloat ill .-i nnuli r id M -a with alii our compartment of nilV omplclcly or partially Hooded, slinnlij In- such that tin- seaplane will not roll or tip ti\rr. 1'rovision is re (|iiirrd against bursting dm- to tin- change in pressure involved in ascending to tin- maximum altitude contem- plated in tin- ili si^n. anil tin lirst lloat of a new type may iectcd to in internal pressure corrcspondiii'.; to this altitude. Suitable skills, kn-N, edge strips, footliolils. walking sirips, etc.. an- required to prr\cnt undue chafe ami we.-ir in service. Towiny cleats .mil nose rings shall In "I :ipprii\cil design ami location. All internal nirtal lillin^s ami all fastenings shall lie copper or brass, ami all \ti rnal metal |iarts shall 1'e ade quatclv proteelnl against the action of salt water. llolis lor fastenings are to he carefully bored and care (akin I" avoid splitting the wood. Units and clinched lioal nails are to I r used in preference to screws wher. \er possilile. 1 )i id nails are not to he used. dim- should not he n lied upon as a jointing material in any lioat or float work. Anv splice, in strength nu inU-rs must IM- .secured hy copper rivets and if possible In whipping ill addition. The type of splice shall in any case he sub- mitted for approval. Any propeller which has not a float directly heneath it is to he so situated that clearance IM-- the propeller tips and the water is not less than two ft. when the seaplane is afloat at rest, or is afloat 1 with the tail lifted to the Hying attitude Pro- peller clearance immediately over floats should be at least two in. Body The form and disposition of body members and fittings are such as to provide positive alignment and minimum distortion under the loads to IM- met in service. For sea- plain s. the crew must IK- able to get out quickly in cas, idcnt. Suitable footholds are to be provided to enable (lie crew to pass to the main floats and to the engines to make minor adjustments while the machine is afloat. Longitudinals may In- spliced only in approved manner. Longitudinal fittings shall IM- properly anchored to take shear, but through-bolts should be used with caution. All wins used for trussing arc to IM- solid except where read- ily acctssiblc. or where the use of other types is ap i. A suitable windshield is to In- fitted to each cockpit. For each seat an apprised safety !M-|| will be supplied. Kcmoxahlc seat cushions are to IK- so attached that they cannot shift when in flight. Engine Installation 1'or seaplanes the engines shall be capable of being 1 by the crew when the machine is afloat in a sea- way. The engines shall lx- accessible and easily removed and replaced as a unit with a minimum disturbance of fittings. Kngincs arc to be effectively cowled with sheet metal, with parts easdx remo\able for access ( owls for rotary engines shall protect crew, planes mil Uxly from oil and smoke Tin exhaust is not to interfere with tin crew, nor is (here to lie any 1 1. -1111:1 r of fire due to it. mufflers are to be provided unless s|M-cfically < xei -pled. Approved provision is to I., in idi tor the .nlrin. exit of air for the purpose of cooling |h, , ML :mc base and cylinder heads. In tractor aeroplanes a flame tight metal bulkhead immediately hi Inn. I the engine is provided. Means are installed in the pilot's cockpit for extinguish- ing lire forward of tile fire bulkhead. The body beneath lyine has a imial cover sloping In the rear with an opening at the r. .r . il^. extending the entire width. The Ivottom of the body hi hind this point is to be ..,\, red ith metal for at least three feet. Suitable drip-pans and drainpipes leading clear of the body are to lie provided to get rid of gasoline overflowing from the carbureters or elsewhere. Carl ureter-float covers shall be so si cured as to prevcir ,.l ^'isoline. Careful consideration should he given to conditions surrounding air supply to the earbureti r In insure that spray and rain are not drawn in anil that freezing dix-s not o.-ciir in the carbureter or induction pipes at high altitudes. A head of at least .'. in. shall remain above the outlet li cylinder when the reserve water allowed has been boiled away or otherwise lost, and with the machine in- clined upward -' ' (leg. to horizontal, or K) deg. list to either side. Radiators shall be tested filled with air at S Ihs. per sij in. pressure when totally immersed in water. Foundations All foundations for engines, radiators, seats, control gear, guns. I., .nil. storage, releasing gear. etc.. are to IM- thoroughly supported from panel points. Fuel Tanks, Piping, Etc. Fuel tank location is nearly central. Gravity feed to irburetor. under normal conditions of flight, or a service tank having at least a half-hour capacity, is pro- vided. I .11 h tank has independent leads either to the service tank or carbureter. If gravity feed cannot IM- ob- tained, proper and approved means in addition to a hand- pump, are provided for supplying the service tank. F.rfi- cicnt strainers arc required in each fuel-tank lead. All solid piping shall IM- annealed after bending. All joints shall IM- brazed. Fuel tanks shall be tested with an air pressure to give three pounds per square inch at the carbureter without showing leaks or unreasonable deformation. Swash-plate bulkheads should IM- tilted and the heads so formed n to prevent vibration. If gravity feed is used, the tank shall IM- fitted with a suitable vent, which will close mil pre- vent leakage of gasoline through the vent in case the air- plane turns upside down. Tanks shall IM- non corrosive and made of annealed material where possible. Filling caps are to IM- secured with chain lanyards. All gasoline, oil and air-pi|M- joints are to IM- electro- conductive, .-md where the joint has to lie made with an insulator, such as rubber tubing, it must IM- short circuited by an approved method. The gasoline and oil supply are to be so arranged that the delivery of gasoline and oil will continue under the normal air pressure (if no fitted) until 266 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING the tanks are empty, in any reasonable position of the machine. The ignition and auxiliary circuits must be thoroughly protected from short-circuits by spray. A positive means of quickly cutting off the gas at the serv- ice tank shall be readily accessible from either seat. The fuel leads, the control leads, and the carbureter adjusting- rod shall be provided with suitable, safe and ready coup- lings where those connections have to be frequently broken. The oil thermometer bulb shall be installed in the oil- sump or other approved location where it shall be covered with oil at all times. The circulating-water thermometer bulb shall be installed in the outlet pipe of the engine near the radiator, or in other approved location. Controls Plans showing the general control system shall be ap- proved before installation. All control gear and control cable shall be readily accessible for inspection and lubri- cation. The control surfaces and actuating mechanism shall be so arranged that under no circumstances shall they jam or foul, and the whole system shall have an approved margin of strength and rigidity. All control gear shall be so placed that it will be pro- tected from sand and dirt. Control wire shall be kept away from floors. All control operating horns shall be relieved of bending stress by at least one wire unless otherwise approved, and control columns, posts, bars and pedals shall be pro- portioned to prevent bending in service. Welding of control horns is prohibited except for longi- tudinal seams. All control leads shall be of stranded cable of an ap- proved flexible type and make, and shall be thoroughly stretched before fitting. Where the control lead passes around a pulley or drum, the wire shall be guarded against coming off. Such guard will not be approved if the cable can be forced off its pulley or drum when quite slack, by pushing the two ends of the cable inwards with the hands. All control pulleys shall have ball bearings. The radius of curvature of pulleys or fair leads for control wires shall be not less than fifteen diameters of the wire for a 90 deg. bend. The turnbuckles in control wires shall be in approved positions as far as possible from the compass, and accessible for adjustment. The handwheel, if employed, shall be made exclusively of non-magnetic material with the inner edge of the rim corrugated. The rim shall be fastened in a secure man- ner and the use of wood screws for this purpose will not be allowed. Each elevator half is to be provided with one pair of operating horns (or their equivalent), each with independ- ent leads. The steering is to be by means of foot bar or pedals, adjustable fore and aft for at least six inches. Arrange- ments are to be made to prevent the pilot's foot slipping off the foot bar or pedal. If a foot bar is used, guides are to be fitted to prevent vertical play; also stops suffi- ciently high and strong to prevent the bar bending or overriding them. The controls need not be non-magnetic for the trials, but if the compass is affected, replacement with non-mag- netic gear is to be made. The fixed control fittings should preferably be non-magnetic, but permission may be given to use magnetic fittings if it is considered that there will be an advantage in weight, strength or convenience manufacture. If, on the engines employed, the throttle and magr advance levers are interconnected and brought to a single lever, this lever shall be operated by a separate hand- lever for each engine. When the throttle and magneto are not interconnected, a separate hand-lever shall be provided for each engine, these systems being so arranged that the pilot can control with one hand the engines in- dividually or together. The hand-levers to the throttle and ignition and to the engine switches, in case of ma- chines carrying two or more pilots, shall be arranged by duplication and interconnection of levers, so that either pilot can operate them when in flight. The forward posi- tion is to be the position for full power. Each throttl or magneto advance lever is to be fitted with an approved system of positive location. A spring, capable of open- ing the throttle in the event of the control gear breaking, is to be fitted at the engine end of the throttle-control system. The engine switches are to be of an approved type and so placed for each engine that all can be moved simultaneously with one hand, the direction of motion for shorting to be approved. Ground wires for switches are to be led direct to the engine and not to the engine mounting. Wings Spruce or Port Orford cedar for wing spars shall be selected from the clearest, finest stock available, shall have a density in excess of 0.36 and 0.42, respectively, based on oven-dry weight and volume, and, if possible, more than eight rings per inch. The spar shall be suitably increased in dimensions where it is pierced by bolts. Particular attention is to be given to this point when the spar is pierced by bolts not approx- imately on the neutral axis. The fitting and its method of attachment to the spar shall be so designed that the failure of any part of it shall not cause the struts to be displaced or both the flying and stagger wires to be re- leased. Either brass or galvanized-iron brads shall be used ' fasten cap strips to ribs; but brass screls shall be used to fasten cap strips to spars. In order to prevent relatively weak portions of the machine from damage in handling, hand-grips shall be fitted in suitable positions near the extremities of the lower planes. Control Surfaces All ailerons shall be double-acting. For large machines in which control by means of unbalanced surfaces will be obtained with difficulty, balanced surfaces of approved form shall be provided. The horizontal fixed tail surface shall be so designed as to permit of adjustment in angle. Arrangements may in some cases be made for this adjustment while in flight. Elevators shall be on same axis tube or locked together in such a manner that the control is not rendered useless if one set of control wires breaks. Wing Struts Wooden wing struts, if hollow, shall be taped, dopec NAVY DKl'AirrMKNT A Kl >1M..\ \ I SPE4 II li \l|,\s and xarmshed. Any *** subtly warped will be operated bx -,, - ,,,, mrtlMcnt mnv rejected. \ ooden ,,ru, shall ,d, ., .,, ,,,.,,, , , J spruce. I'ort Ortord cedar or white ,,- of finest grade. .ilenm load*. close grained ind Hell -eason, ,i. I or struts the inspector will select -prucc or white |>itic ha\ing :i .. 'Hi or I'ort Orford c, dar li:i\iu^ a dcn-itv in excess of and. if possible, more than eight rinijs per inch. Propellers Tli. propeller hub fncepl.it,-, shall be intcrconn imlcpi -ndent.y of tin- propeller bolts, so that each plate is used to drix, the propeller. Wood propellers shall be fitted with sheathing wlii<-h sh.-ill extend a distance from The total lift load ..n each wing in ih. product of thr f that wing by it, i,.,,t load ,n,l a ,-,. d to U- applied uiiifonnly .ilon K the -pars .-,, l( | di-trihulcd b. them , imrr-c pro|M.rlion to their chord di-lancc, from 'MM. ,1 center of pressure. At high -p,,-,| i|,, t. r of pressure -lull IH- assumed at (..'. of the chord di, In... from the leading , ,, t when r ,.|, ,|,| ( . , tunnel data on the center of pressure trax.l and , plane life .-..crticicnts for the aerofoil employed are axail able, in which ease the center of pressure for high Non-corrosive the tip of the 1.1.1,1, toward the center approximately on, mix l- calculated from the wing loading it high rth the diameter on the leading edge . m d ,-ight inehes by obtaining the riving angle from the monoplane lift on the trailing edi;., is a iiiininiuiii ; detailed requirement- characteristic. At low -| H -ed the center of pressure shall may be found in Bureau of Steam l-'nginci-ring. Instriic- be taken at (l.-.'H of the chord distance from the I. edge, mil, ss an unusual aerofoil i- employed, in which he center of pressure travel may be modified if data from wind tunnel tests are available. I!. -ides the lift load defined alx.xe. the wings carry a drift load which may U- assumed equal to one-quarter the lift load and applied at the center of pressure. Tin- drift is assumed to include the drift of wings, struts, wir- ap|H-ndages. \Vherc data from wind tunnel test* arc quoted, the fraetion of lift applied horizontally as drift may be altered. Thi.s drift load may then IN dni.l.d Let ween the spars and distributed uniformly along them. Kesolve the running lift and drift loads for each spar into a single running load in the plane of the principal axis of the spar and. making use of the Theorem of Three Moments, compute the bending moments in the spar and the reactions at the joints or points of support Assume, as a first approximation, pin joints with all loads concentrated on joints and compute direct sir. each member after having nsoUed (he loads into the planes of each group of member- i. c.. plane of front struts, plane of chord of top wing, ete. For apart, com- bine the direct -tresses due to lift and to drift with the stress due to bending. The horizontal ihrar in the wing spar- -hould br com- puted for section- near the strut ends where the par h* its usual section. Directly over the strut- the wing spars shall not he hollowed out. and if pierced by holt holes allowance -hall be made in all computations for the sectional area of the holes. Wood spars of I -section shall have the web at least equal in thickness to the flanges and eut with gener- ous fillets. All splices iii solid wing spars shall be loeated at (mints of eontratlexiire or minimum bending moment. When the exaet location of these points is not known, they may be assumed to oeeur at from one-fourth to one-third the dis- tance between consccutixe interplane struts Splicing of iml.iiiun.it, d spars or of lamination* of lam- inated spars will be permit ted provided the type of spin, is appro* cd by the Department. In splicing solid wood spars of I-section the spliced fee- lion shall not le routed out. Fittings for pin-joints at butts of wing spars are to be designed so that securing bolts cannot crush or shear through wood under loads specified below. tion- for Tipping Seaplane Propellers. riiet- or screws shall IK- used. FACTORS OF SAFETY factors of safety specified apply in general to all aeroplanes. In all case- the burden of proof rests upon th, contractor to demonstrate by submission of his calcu- lations in detail that the aeroplane is structurally safe. Any part or parts whose strength is in doubt shall be tested by sand loading or other approved method. Thi.s specification refer- in particular only to the most impor- tant structural members. I'or foundations, terminals, tit- ting-, bra,-,- and minor structural parts, for which calcu- lation- an indeterminate 01 loading unknown, good en- gine, ring practice shall be followed. Th, wing truss con-i-t- of the wing spars, interior brae- rut- and exterior bracing together with all wire or cable anchorage-, but does not include non-strength parts. such is leading and trailing edge strips, ordinary ribs, tap,, doth, battens, corner blocks and fairing pieces. It nned that the wing truss carries in normal flight the full weight of the aeroplane and, in addition, the drift of the wings, struts, external wires and any appendages, such as skid fins, wing floats, etc. In biplanes the distribution of loading on the wings shall Ix- computed by the formula: 11 - + AX, (i) 9 in which W = total lift load, A* = area of upper wing, = area of lower wing, and x = unit load on the lower which is obtained by solving the above equation. In triplanes the distribution of loading shall be com- puted by the formula: 5 3 W = A-x -f A-x + Ax, ( 2 ) * 4 in which A" = area of middle wing, and other notation is me as in ( I ) . -tresses imposed in the wing truss are figured from lift which equals the total lift less the weight of md the interplane bracing. Aileron- are considered as wing area, but in special when ailerons are of unusual design or si*e. or 268 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING Struts shall be computed as if made with pinned ends whether or not the ends are actually pinned. For it-ires and cables allowance should be made for the efficiency of the terminal. Similarly, the strength of the fitting to which the wire or cable terminal is secured must be considered in the wing truss design. Wires and cables should be so led as to introduce no eccentric loading on structural members and anchored in fittings designed to develop their full strength. The stagger wires are to be assumed to carry the drift of the top plane. Where the top plane passes over the body, the entire drift of the top plane is assumed to be carried into the body by the stagger wires and struts at that place as if acting alone. Cross transverse diagonal wires over the body holding the top plane from racking as the aeroplane rolls should be computed to hold the rolling movement obtained by as- suming an up load of 20 Ibs. per sq. ft. on one set of ailerons and an equal down load on the opposite set. Wood Air seasoning is preferred, but forced drying will be permitted if approved methods are used. Laminated wood shall not be used unless approved by the Department. Spiral grain will be allowed only as permitted in specifi- cations issued by the Department for each type of ma- chine in production, and in case of doubt test sticks shall be split. No spruce or white pine below 0.36 density, Port Orford cedar below 0.42 density, or ash below 0.56 density in oven-dry condition shall be used in important strength members. Wood splicing shall be only as ap- proved. The splices shall be of efficient form and the grain shall not be turned. Bolts or rivets shall be used if required, and the joints shall be finally taped or served and glued as prescribed. All dope, enamel, paint, varnish, shellac, waterproof, hide or marine glue shall conform to Department specifi- cations. Metals Where the material is of a class susceptible of improve- ment in quality by heat treatment, such treatment shall be given as a final step in manufacture, except in the case of small parts. In the latter case the heat treatment shall, if practicable, be given before fabrication or else the parts shall be made from heat-treated stock. Steel shall not be left in finished parts in a hot-rolled, hot-forged, or cold-forged condition. Normalized steel must be renormalized after forging (hot or cold), welding, or otherwise heating. Hard-drawn steel must not be heated. Laminated fittings of metal which are brazed or welded shall, in addition, be thoroughly riveted. Welding and brazing shall be restricted to parts not otherwise possible of fabrication, and only in approved locations. Acids will be used in soldering only where expressly permitted. If used, after soldering, all acid shall be neu- tralized and washed out in an approved manner. Wire Solid wire shall be carefully formed to perfect eyes without any rebending, and the eyes shall be properly formed to prevent crawling. Eyes should be examined for signs of lamination and cleavage. Cable shall be tacked with solder before cutting or cut with acetylene , flame to prevent uneven stress due to unlaying. At the time of tacking the wire shall lead straight. Wire with hemp centers shall have the center locally] removed before making up the terminals so that the cen-l ter strand will carry no load. The ends of all cables, whether flexible or otherwise, shall be fitted with thimbles or other approved device to minimize slackening in serv- ice. Where cone cups are used for terminals the double i mushroom may be required unless the workmanship is such as to show by test perfect terminals in every case. Taper plugs shall not be used. All wire terminals except those of the cone-cup type shall be soldered. Cone cups will be puddled with zinc and care taken to prevent draw- ing the temper of the wire. Wherever wires are inaccessible for adjustment, as is! the case inside the wings and auxiliary surfaces or in parts of the body or floats, solid wire shall be used un- less otherwise approved. Cable stays shall be made up complete witli terminals and proof stretched before installation with a load equal to one-quarter of the ultimate tensile stress. Fabric Wing, body and auxiliary surfaces shall be covered with- linen or cotton conforming to Aeronautical Specifications, C & R Nos. 12 and 13, respectively. On the wings, the fabric shall be applied either diagonally or with stains running normal to entering edge. On the wings, the tape and lacing method shall be used, with loops spaced not more than four inches apart. The thread shall be knotted at each loop or made fast with a double half-hitch. and then cemented with dope. The tape used in wing construction shall be of the same quality of fabric as used for the wings. Tape used on laminated struts or built-up parts shall be applied with glue and then doped. Thread used for stitching seams shall be of an approved linen or silk and shall be waxed. Pontoon Fabrics In built-up laminated floats, bottom planking and bulk- heads shall include cotton sheeting applied with an ap- proved grade of marine glue between laminations. Requirements of Finishing Materials Acetate and nitrate dopes used on all work shall be ifl accordance with Aeronautical Specifications, C & I 1 and 2, respectively. Spar varnish and naval gray enamel used on all work shall be in accordance with Aero- nautical Specifications, C & R Nos. 3 and 4A, respectively. Doping The doping of all naval planes, with the exception oj H-16 and F-5, shall conform to the Navy Standard Dop- ing System A. Navy Standard Doping System A Wings, control surfaces and fuselage fabric On all fabric two coats of cellulose acetate shall be applied This treatment shall be followed by the application of sufficient number of coats of cellulose nitrate dope no NAVY DKl'AHTMKNT AKKOI'I.ANK SIM-.C 1 1 It ATM )\ > le-s than two or more than four coats to obtain satis factory tautncss and tinisli. After the last coat 1ms dried for nut less than twelve hours. na\:tl gray rnamel .shall he applied: two .-oat- on \crtical surface, two coat- , IM top sides, and on.- coat on the under side of horizontal sur- faces. () I' l"> '"'I I planes, acetate dope shall conform to Navy Doping System B. Navy Doping System B Wings, control surface- and fuselage fabric On all fabric the successive eoat>. of cellulose acetate dope shall he applied. After the last coat has been dried for not less than twelve hours, naval gray enamel -hall lie ap- plied; two coats on vertical surface, two coats on top .sides, ami one coat on the under side of horizontal sur- faces. Finish for Metal Parts Plating '/.'me coating is preferred and should be used wherever practicable. When galvanizing is employed, the zinc coating should conform to Aeronautical Specification-. I \ H No. ;;<>. Special alloys and heat-treated steels may l>e affected if galvanized by the hot-dip or other proc- esses employing high ti-mperatures 375 to -150 deg. C. On such parts, as well as on accurately dimensioned small parts, the electro-galvanizing process (zinc plating) should In given preference. I 'leaning Sand blasting is preferred for cleaning metal previous to plating. Pickling of metal surfaces with acid should be avoided wherever possible, since pickling increases the brittleness of metal and has a very unfa- voral-le effect on thin stock. Pickling should especially be avoided on metals that may IK- subjected to continual vibration. Wherever pickling is used, the metal should I" thoroughly cleaned with water so as to remove the pickling acid previous to plating or finishing. Threaded and bra/ed parts are often cleaned satisfactorily in tum- blini; barrels with oil and emery. Painting After plating or coating with zinc, copper or nickel, metal fittings .shall IK- finishcl with enamel. Specifications (' & R No. lA gray or No. :> black. After assembly all metal parts that show bare places shall be touched up with enamel. Interior plated or zinc-covered fittings such as tubes or aileron horns and all such parts having cavities shall lie dipped in enamel and then allowed to drain and dry. This process is included to insure in- terior protection against corrosion. Steel tubes having sockets or caps on the end may be drilled with two hoi Thinned enamel may be poured in one hole and allowed to drain. After enamel is dry the holes should In- plugged. Wires and Cables All fixed external wires or cables shall be carefully cleaned and coated with spar varnish containing 5 per of Chinese blue. All fixed internal hull wires or cables and all internal wing wires or cables shall be painted with naval gray enamel. All control wires or cables shall be heavily coated with an approved grease. RULES GOVERNING CONDUCT OF TRIALS I 1ect to a wind of a velocity between 15 and 20 m.p.h. Maneuvering on Water Seaworthiness will be demonstrated by maneuvering the surface at anchor, adrift and under way. The purpose of such trials is to determine staunchness. stability, planing power and longitudinal and directional control under varied conditions of the wind ami sea. representative of conditions to be met by the ty|x- under consideration. In a calm, with full load, the seaplane shall steer read- ily. At all speeds up to " get away " the seaplane shall respond readily to the controls. It shall " plane " at moderate speed, accelerate rapidly, and get away within the distance specified. It shall show no uncontrollable " porpoising " or tendency to nose over at any speed. In.!, r this condition the pro|x-llcr should be free from spray and broken water. In a moderately rough sea the seaplane shall steer TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING 270 readily in all directions and at all speeds. It shall "plane" at moderate speed and without undue por- poising " or tendency to nose over under any condit with the wind forward of the beam. With the wind abaft the beam it should be capable ( running slowly or- at moderate speed without nosing or without undue spray or broken water entering the pro- peller disk. Down wind at wind speed there should sufficient reserve of stability to prevent nosing over Headed into the wind there should be no marked 1 ency to yaw. In a rough sea the seaplane shall steer readily in all directions at moderate speed, and shall steer readily at anv speed with no tendency to yaw with the wind any- where forward of either beam. It should be able to get off and to land headed approximately into the wind w.tl out undue punishment to the seaplane or propellers. Adrift or riding to a sea anchor or to a ground anch the seaplane should not take any dangerous attitude in a calm, moderately rough sea, or in a rough sea. v ii API I.H VI METHOD OF SELECTION OF AN AEROPLANE WING AS TO AREA AND SECTION Bv .1. A it,,, ,,,. \| \ This ph-isc of design, although ,,f ,.,..,, imp,,,-!;,,,,.,. ,f the hitthest etfici, ncy is to ! attained, li.-is loin; |,, ,. 'tl. 'I'll,- first reason for tins was (lie lack . pcrimental data on which i-,uii|i:ir:iti\i- calculations could be IMS,,!. ..,,! now that this datn is plentiful ami trust worthv. there is IIM ,|iiick -Hi, I easy way t.. I, -ad MM,- to t In- correct <-iriat i,.n !' section and area to he us,-,l. This dith'cultx aris.-s fnuii tin- tact that Imtli section and area ire funrlioiis of , ai-li other and also of tlu- weight, power, head resistance and intended purpose of the guchine. Aii\wa\. an aeroplane is pretty sure to fly satisfactorily rovidini: t |,.. lt die relation between tile aliove factors IH- hoseii with " ii..,.|>l for In in.p h. Ii thr rc sought It is generally assumed that the se//>, tj J.H iwrwi' i I ! t I nil i-lvirt- 271 of TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING 272 useful load to be carried and we are given a power plant. There are seven variables to be considered, namely: K f , /v A, r, S, V, W. These are related by simple expressions: T = A 1' 1 1 to allow for the greater efficiency of large planes moving at high speed. We can also multiply the area by 1 08 to allow for the greater efficiency of the aspect ratios commonly used. Finally A, being affected by interfer- ence, can be multiplied by .1), the equations thus corrected become : \y Where K x c c inriirinary square plate whose air figteMe WOttld be equal to that of all the struc- tural parts of the machine, or to the pa. sistance. K = The coefficient for A sq. ft. X m.p.h.- nm-^ft ~" His. P = The power available in Ib. miles per nr. V, S, W, A" B as above From which we get by transposition and cancelation : It now becomes necessary to apply to these equations the factors that will make them yield results in terms of the desired units and those that will compensate for the following: Aspect ratio, reduction of size and wind velocity, interference or biplane effect. All possible care must be exercised in selecting these coefficients; they will be different for different types of machines the' following are not chosen with any type in view. Some valuable indications of these coefficients may be found in Loening's " Military Aeroplanes " and in Eiffel's books. Mr. Eiffel recommends that the area be multiplied by 1.08 x 1.1 X 9 X KA K_=- - 1.1 xi.osxsr-i 1.1 x i.os x LIB -si- It would be more accurate to apply these corrections toj the characteristic curves of the wing sections tested; how ever the errors of this method are slight, and since same error is introduced in all cases, the value of thisj method is not impaired for purposes of comparison. Consider the graph of these equations, K, being plotted against K a for various values of V and for assumed co. stant values of -S, W, P and A. Note that these equations give the value of A, neceitart to flv and the values of X, available at various velocit Note also that the effect of the second term of equation is merely to subtract a constant amount from tl K. which would be available were there no head resistance This amount depends only on A and S and its value is real on the X, scale of the diagram. The effect of this term is then to displace the origin of the plot to the right alon| the A* axis. In order that this origin be easily locat for any possible value of A, which will naturally vai according to the dimensions of the machine, and for t values of S under consideration, a set of lines is drawl as shown on lower left-hand corner of wing select* CH/jftT rOR THE PETRr-IINRriON^ or . Jj^j;("' : " SS '"' rl CHKRT FOR I ' ' Mj-- ro\, 7V> eo" 90 v too a.*. * AVinr selection diagram calculation charts used to facilitate computation of coefficients and calibration scale used to gra| diagram MFTH01) OF SFFFCTION OF AN A FI{()1M..\ \ F \\l\c. 278 agram. from which th<- valm origin thus 1 . 1 ' x H-atcd fur any given Conditions. I'sing this in w origin , values remain as tiny were. but tin- new A v ili;. - in HIT that rrmniii to drive tin- wings alone through tin nr \" consider tin- |i|:ir curvis nl certain tested wing ctions; these curves tirst il. -vised b\ Mr. l.illil s, em to c by far tin- most ingi -nioiis method of represent in}; the ri^tics of a win.; MI linn, anil I wonilrr why their has not lieen more widely adopted in this eonntry. olar curvi -s can lie den\ed. however. from anv other i-ristie eiir\es available. nr translated to Ih. i|. if units and si/.e from tun inn polar curves. that these eurves give the A', rfijuirrtl by tin- i-tion to nio\e through the air nt various angles and tin av.iilal le with tin- section if it is made to travel at rioiis incidences. Then recalling the matter on page I- lie A rripiireil A lil.iMi -- A" v rr|iiirrl = A^ excess A . - - X AV- = Kxccsx power I I I MCM liftinp capacity. extra load which ennlil have lirrn cnrrii-d. = % excess power h' 100 - rr-r-. A available e\i-ess X 100 = % excess lifting capacity. A^ nvniliililr Tin si \ ilues as well as the speed ranges, can be ob- imd easilx for se\eral combinations of section and area superposing polar curves and the diagram, several amples of which an ^i\en lati-r. It is i\id'-nt that the above excesses arc the horizontal --rtieal inten-epts between the selection curve nnd e polar curve and when these excesses are ero we have e limits of Hight range. \\ . can at once proeecd to illustrate the melli.nl by an ample : Let U wi j.;ht of maehiiie complete with load 2500 III' 120. available with variable efficiency. niiig various values for V we can tabulate values r K, and K, for values of S. Let us try 250, 350 and sq. ft. Then plot the curves of A"/- in function of A', ritini; on the eurves the velocities for which these eoeffi- nts occur. This will be our wing selection diagram. A CIITM- in the example is also given for .S5O sq. ft. id HUM) Ibs. to stimulate empty gas tanks, in order to ow the conditions of flight when the machine is light. The peculiar waves in these eurves are due to the riable efficiency assumed for the jMiwer plant. \Ve know at this varies from zero when the machine is standing ill to .1 maximum value when the machine is going near highest s|K*ed. and then decreases again. If the effi- ney was constant these curves would IH- of the simple i: \ ri '... + r which it a parabola. The tabulation and diagram follow: = Assumed efficiency of power plant /// X K = Power available. The values in the following tabulation can be obtained cans of a slide rule or by the use of the accompanying kits. V K H.P.X. F IM MM 4.MO ZU.M . .. .. : . - .. n S 744 nc HI i 84. Ft. K For 4WS l.lhl V K J 40 n - 11" ' . .-Mil v .mm - .0004T7 M n 7* II* . The above tabulation could be further improved by letting the weight change for each value of area, as would be the cise in practice. The effect of this would In- to bring closer together the ordinates of points on the dia- gram. us provide ourselves with polar curves of the wing sections that we wish to consider and draw them up to the same stale as the diagram. For ease of inspection, either the |ilars or the diagram should IK- on transparent paper so that we may place one over the other and still see both. To supply the example. \ polars of to-day'* most fashionable curtcs are herewith presented with the selection diagram superposed. With the alovc material at hand we can now proceed to select our wing. The observations can be tabulated as follows: T La* J 274 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING READINGS FROM WING SECTION DIAGRAM READINGS PROM WING SECTION DIAGRAM Section Area High Sp'd Low Sp'd Best Glide Excess Power Section Area IIU-h S|,M Low Sp'd Host Glide E\r< ss 1'ow V i V i V i Gd. % V i % V i V i V iGd. % V i % R. A. F., No. 6. 250 350F 350L 450 83 314 77 214 77 114 Tl.r, I'.. 56.6 15% 48.3 16 42.2 17 42 16 60.5 8V t 12.5 56.5 7% 11.75 49.5 7V4 11.75 53 6 11.1 65 8Vi 22.2 54 814 32 Eiffel 47.5 8% 51 No. 36 48 8 39 250 350 F 350 L 450 85 2% 79 1 80 -14 74 1 59 1214 4SIL- 14 41% 16 42.7 14 72 5 13.1 73 5 12. 54 5 12. 56 4.5 11.25 69 7 15 72 5 22 51 5% 47 53 614 35 Eiffel No. 32 250 350F 350L T-0 Sli 1 -- 83 3 87 iy 8T 2 61 1314 50 15 43 17" 44 15 77 6 13. 65 6 11.75 55.5 6 11.75 59 514 11. 75 7 15 63 614 27.3 Eiffel 55 6% 47.4 No. 38 55 614 35 250 350F :J5UL 450 85 214 80 1 83 -V4 77 57 13 47.5 14 43 16 42 14 67 6% 12.25 56 6% 11.25 49.5 614 11.25 52 5% 10.62 67 7 23 56 7 34 19 7 52 50 6% 40 : 4 ' .'_/4iH jyn ' POCAR CURVE FOR 5ECTION N3Z (EIFFEL) t Unrft m lb. pr s<^. '>* aos. Mumencal .041 :L:ig . . POLAR CU ... .., 7 i SECTION N9 3S // /;, ' i Unitj , n Ib -m j it pfti- mi. -W/r j ' - TRANSLATION I S'je 2.08. Him j_| ' -I ri.iir nj_ i ;- i:-- ; d .- J - 1 - S P0f 3l. ;: POLAR CURVE FOB SECTION N38(EIFFEL) Units IB Ib5. per Jest j-lulin^ nn^le, on the snine hortxontal i.l Ih. , ..rri -spoiidiiiu spin), (he slope i{i\es the value of the Ix-st ^liiiing gradient. I Tin httle diagram in the lower part shown how parasiti resistance ciils down the spied and CXCTM |n>wer and its nlati\e importance on m-iclum s of largr and Miiall area. The accuracy of the |M-rform.ince pr si d \>\ this method d.-p. mU on the accuracy with which the head resistance, power avnilaltle anil the currection factors II.-IM- l>een determined. The accurate selection of each one of thcuc presents a prohlem hy it- It CHAPTER VII NOMOGRAPHIC CHARTS FOR THE AERIAL PROPELLER Bv S. E. SLOCUM, Pn.D., Professor of Applied Mechanics, University of Cincinnati; Member S. A. E. In discussing propeller performance it has been cus- tomary to assume that the power absorbed by the pro- peller varies as N*D r> , and that the thrust varies as N 2 D*, where N denotes the propeller speed in revolutions per minute or per second, and D is its diameter. These as- sumptions, however, are only true for an ideal propeller; that is, one which is perfectly rigid and perfectly sym- metrical. For a propeller as actually constructed, the law governing power and thrust may differ materially from the above theoretical assumptions. The actual laws governing propeller thrust and power for a particular propeller were developed directly from experimental data obtained by M. Eiffel and Captain Dorand, without mak- ing any theoretical assumptions whatever, the method em- ployed being the standard process for the adjustment of observations by the method of Least Squares. The re- sults showed that the performance of a given propeller may differ materially from that prescribed by theory for an ideal propeller, and also showed how experimental data on propellers may be analyzed on its own merits, inde- pendently of all dynamical assumptions. As long as the whole subject of propeller performance was in the experimental stage, it was doubtless wise to base all calculations on the assumption of an ideal, pro- peller, as it gave a certain uniformity to results. At pres- ent, however, when propeller types are becoming stand- ardized, it certainly permits of greater refinement in de- sign to determine by experiment the characteristics of the standard types of propeller adopted. This is the method followed in all lines of engineering. For instance, the performance of aviation motors is determined for a given type of motor by actual test of this type and not solely from the principles of thermodynamics, while as another example, the firing data for a long-range gun are based on experiments made on this particular type of gun and not on the ideal assumptions of a perfect pro- jectile fired in vacuo. Of course it cannot be expected that general formulas for thrust and power can be derived which will apply uni- versally to all types of propellers, any more than that a gas engine power formula can be derived which will apply accurately to all types of motors. It is perfectly pos- sible, however, to derive formulas by the method men- tioned above which will apply accurately to a given type of propeller, which will assist materially in the problem of powering aircraft, that is, in determining the most effective combination of motor and propeller for a given wing and fuselage assembly. The formulas so obtained, however, are exponential, and consequently somewhat difficult to use in their algebraic form. To represent graphically the various combinations 276 of quantities involved, M. Eiffel devised what he called Polar Logarithmic Diagrams," which constitute, in fact, a very ingenious and practical application of vector al- gebra. But the application, as well as the theory of these diagrams, is rather complicated, while the results depend in part at least on determining the intersection of lines which meet at an acute angle, and such points of inter- section are liable to a considerable error when determined graphically. There has recently come into use another means for the graphical solution of exponential formulas which is similar in principle to that devised by M. Eiffel in that it depends on the reduction of an exponential to a linear form by the use of logarithms, and the employment of logarithmic scales. This device consists in the construc- tion of diagrams called nomographic charts, or alignment charts, from which the required results may be obtained by simply connecting the points representing the given data by straight lines, and then reading off the intercepts on the proper scale, the method being similar to that of using a slide rule. In Plates I and II accompanying this article, no >- graphic charts are shown which represent the formulas for thrust and power of the aerial propeller as previously derived by the writer in the references given above. These charts, of course, are not universal, as they simply represent the performance of a particular propeller, but similar charts differing only very slightly from these may be constructed for any standard type of propeller, and their use will facilitate calculations on this propeller to the same extent that the use of the ordinary slide rule simplifies arithmetical calculations. It may be noted that the effect of varying the ex- ponents of N and D will be to move the intersection axes slightly to one side. For instance, if we follow the theoretical assumption that the thrust varies as A' J 7) 4 , the intersection axis on the thrust chart will be moved slightly to the right of the position shown; while sim- ilarly on the power chart, the assumption of N 3 D' > will also move the intersection axis slightly to the right. Like- wise any change in the quadratic terms involved in these formulas will affect the relative location of the points on V the scale giving the ratio , and in this way change the ND readings on the horsepower and thrust scales. Except for such shifting of the intersection axes and changes in the graduation of the various scales, the nomographic charts will be exactly similar in form for all types of propellersj Having determined the thrust and power for a given propeller, the torque and efficiency are easily found. Thus DIAMET Fee PROPELLOR SPEED N ER D t * J -4 7 4 bx Eumpl* of .,.|.lir.uon of rh.rt. SnppOM X (t |.ro|*ll,r Ml X = 1400 r p m. mtt 130 fl w. Tba = .60 O Draw line Joining UM point D - H oith UM IntorMcUon *>U In Uw point A .li.in i $ lot = .60. Tb IntcTMrtlon of Ihw I M' Kl (im 300 II I* |.|.ruiinu>ly. p ki HORSC POWER s -to -30 fa -_ ^^^ A JOO 4OO POWER /oo FOR AERIAL P t iliimrirr I> ,|i.., lini-ar vrlocity V = Hi.' iMiint N - 36. rullinc u- ,...,,,! A with tin- |Kilnt nr with thr bone powrr ATI jTO -1.00 -AS -JOO -Jf -.70 -J0f -40 CHART THE =OPELLOR M- /wo /700 AMU -/o 14- XJt- Zl- /JJO\ 'JOO >y It- 11- \ //jo X -/OJO \^ /too 9SO a- -esif 1 O, -too -ISO -700 -6SO NOMOGRAPH OF THE FORMU - t , O76 *-** J". /S f -\r /\f Rfi. ip- N D ri + *4X.- LA f] cum. 7S6 SSO -5.ET.5lo DIAMETE Ft PROPELLOR SPEED N Rcv./5*c Re^MIn R D et p s s 6 1 II ~ut THRU5T CHART FOR THE AERIAL PROPELLOR NOMOGRAPH OF THE FORMULA jt *7- -/7J-0 -I7OO -tffo -/too -/.WO Z ' 30,000 L VNW J g ^ RAT or u h TMRUiT Z Pounds 10 -90 -4O -100 ~ 4-OO ZIOOO 4000 ^-JOOO ^-4000 Hj2. E./OOSO Ezcmpw of pplication of chart. Oirn D = 8 ft, N = 1500 r.p.m. = I V SS ft . Join th |Kint D = to UM point N - 35, rutlm t B. Join B to UM point = .60. Th Inur-clion of thl II ND UM tbruit teal* cie F = TOO lb>. 5. &.olo< jfe -JO Jl -40 -.70 -60 ^*** ti r r hi- n r with um. *.!- */- -1*30 \. /- /7- /- -lisa -1100 \ \ -ioso X -/ooo -*JO /J- /a- //- /o -AM -400 -WO -700 600 277 PROPELLOR TORQUE T -SPEED N Ft.Lbs. THRUST F LINEAR VELOCITY V o c ' Lba. Fi/'Sec. 4Op 400 - ^s ^--5-00 60 40 - ,000^= ^Ss B^ 70 SO ~ EE ~""T^^^^ C o 60 ~"==^ _____ 70 - .300 ~--~^^ /oo 30 SO /S fZOOO _ 4-00 ^000 ^~^y/o^ /oo 3000 - _ _ /i*=> _ -*ooo 30OO /30- /40- JOOO-^ 4000 /SO z= = tooo =- - /Mao = Er- ^oo- Ann =/0 ooo ZX.O Example of application of chart. 1. Given N = 1500 r.p.m., H.P. := SUPPLEMENTARY CHART 200. Join these points. Intersection of this line with torque scale gives torque = 700 ft. Ibs. 2. Given thrust = 700 Ibs., lin. vel. = 120 ft /sec H.P. = 200. Join P = 700 with V = 120. intersecting efficiency axis in point C. Join this point C with H.P. = 200, and prolong to intersect efficiency scale giving efficiency = 78%. FOR TORQUE AND EFFICIENCY Rrf 5 O ' -5.E.^Jocum. Application of Chart. Given D = 8 ; N = 1500 r.i>.m.; V = 90 sec./hr. Construction shown, as explained on Plates 1, 2 and 3, gives H.P = 180; P = 590 Ibs. ; T = 650 ft. Ibs. ; Eff. = 76%. h "0 =v 0,000 COMPLETE NOMOGRAPHIC CHART Firf 4. FOR THE AERIAL PROPELLOR 278 NO.MOC.KAIMIU CHANTS 1(>K Till. \l K1AI. 1'IJOI'I I I IK .111(1 I,.,,. \ ilwork I \. Klliclcnev = : work .'.:>o h.p. whin /' (Iciiiiti-s tin- |ini|irlliT thrust, .-mil /' is tin- s|M-cd of tin- plain-, or r.-l.itm M locity of tin- wind witli r to tin- propt-llrr. To make tin <;raphic.-il solution com pli-tr, howcicr. DOmOgraphiC chart-, nriy also In stnicticl tu i;i\c tori|in anil i th'cicncy . as shown on Plate- Ill. These charts art- presented separately in Plates I, II -iii.l III tor tin sake of rh arm-is, and an example of their use i-- shown on each. I or jiru-tii-al purposes it is more eonvrnirnt to put all tin- . Inrts on oni- slu'i-t. as shown on Plate I\ . As an i-xaniph- of its use it may Ix- well to follow through the ron>' rurti. in shown on Plate IV. In this example we are uiv.ii pni|H-llrr ili.-iiiii-ter I) = 8 ft., pn.pt Her speed AT=;I.,iiii r |, I,, j :, r.p.s.; linear sprrd /' = 9O miles |MT hour l.ij ft |H r Mft 1 irst join \ l.'.tMl with D=K, flitting power axis in A and thrust axis in It. I I BteH =.66, join . I with this | M iiiit on the .scale \l> M> for powi-r. Tin iiitim |!> Ihs. Now join h p. = 180 with .V ---- I.MMI. Tin- intercept of this line with the torque scale gives Torque T = 630 ft. Ibs. Lastly, join the point Thrust f=S90 with the point / on the velocity scale, cutting the ilicn-ncy axis in tin- point ('. .loin this point (' with the point h.p. I HI). The int. r i-ept of this line with the efficiency scale gives Effi- ciency = 76 per cent CHAPTER VIII METHODS USED IN FINDING FUSELAGE STRESSES BY J. A. ROCHE, M. E., Aeronautical Eng., U. S. A. Reasoning Leading to Choice of Criterion and Methods Used in Finding Stresses An aeroplane fuselage is a structure whose function is to connect the wings, landing gear and tail surface, of the machine; hold them in their proper respect, locations and transmit the stresses which hold the machine in equilibrium, in the air and on the ground from ea< one of these parts to the others. Its secondary function is, of course, to house the engine, aviator and accessor.es While in the air, the fuselage transmits from the tail planes to the wings moments which are necessary give stability or to neutralize whatever couples may exist due to center of pressure and thrust line locahon. In normal flight, the stresses due to these momenl are slight, but in exceptional cases such as in recovenng from a vertical dive, these moments and the thev cause are large. It may seem at first that these can reach enormous values if the recovery be made very sharply by raising the elevators at a high angle, while traveling at a high rate of speed. It has been measured that a man in the pilots seat can exert a push or a pull force of about 250 pounds. With the leverage of a standard " Dep." control, the force that can be exerted on the control cables is about 600 pounds and this can bring about a reaction of 400 to 500 pounds on the elevators according to their shape, on which depends the position of the center of pressure behind the hinge. The resultant of these two forces is as shown by the above figure, and this resultant can be used as a basis for a stress diagram of the rear end of the structure. The stress diagram yielded is of the simple usual type. Usually no attention is paid to stresses in the rear end of the fuselage caused by landing shock and the front end is analyzed by itself in a rather crude manner. The object of the following is to investigate the latter condition as thoroughly as possible, taking into account, Location of landing gear, Location of center of gravity, Inertia forces, Point of application of all loads. As a machine runs along the ground in normal position, the reaction force applied at the wheels, being equal and coincident with the resultant of the loads and inert,; forces, must pass through the axis of the wheels and also through the center of gravity of the machine, not strictly true, because other forces may be at pis helping the machine, namely: airloads on the mam pis and other surfaces; however, it would be fair to assume that the roughness of the ground produced a force equal to the inertia forces. If the rolling friction is very high and the machine has a tendency to turn her nose, the t air loads must act down to keep the machine in equil.bm whereas if the rolling friction is too low the tail air loads must act up to keep the machine rolling on her wheels In the latter case, the machine will have a tendency to porpoise; in the former, it will have a tendency 1 nose over, but it seems that if the wheels are so local that the resultant of the weight reaction and rolling friction passes through the center of gravity, the aeroplane will then be stable as it strikes or rolls on the ground. It is true that the rolling friction is a very variable factor, but it certainly has a mean value and we cai assume that the inertia of rotation of the aeroplane will take care of most variations from this mean value of rolling friction. It is not advisable to assume the machine landing wit a perfect " pancake " and striking with wheels and skid together, for this is neither the worst nor the usual con- dition of landing. It is preferable to assume the machine landing on its wheels only in normal horizontal position and with tail planes neutral, which is a fair mean between the possible conditions mentioned above. The stresses found can be those due to the normal loads taking no account of shock ; and since shock would not alter the direction of the forces but only their magni- tude, the stresses for any condition of shock can IK- obtained later by applying a proper constant to the normal stresses or by changing the scale of the stress diagram. The work can be performed according to the following plan: 1. Draw to scale the fuselage under consideration and mark on it the centers of gravity of the various loads 280 MKTHODS I'SKl) IN FIXDIXt; 1 1 SKI .\(. I. STRESSES 281 which it must carrx : label r;ich one with it-, n r weight. Discompose each one of these loads .mil apply propi-r share to each oin- of tin joints on whirh r I. Draw \i rlical and hori/ontal fiinirulnr polygons or two polygons at an angh to ,- ich olhrr. The intrrsr.-lioii of tlu-ir resultants gi\es tin- position of tin- << nl gr.iv ity of tin system. Draw reaction force passing thro< Mills found and center of axh . make all load Motors parallel to it. J. Draw stress diagram, closure will In- considered as l-hrrk on the work. i rach inrinlirr according to tin- stress it carries, taking bending or Ir.inswrse for,, , hitii account. I ..r tin- portion of a strut In-low the point of application of the load add to (In- direct stress shown by the stress n tin portion of that load which had been consul ere, I .-is applied at 'In- lower end. For the upper portion, deduct the portion of the load which had been consul, re, I pplied to the upper < nd. It was admitted in step 5 that the stress diagram was not the final operation in finding the close value of strr ~,, - in the members of the fuselage. This is due to ict that this truss is loaded internally. Before starting to draw the diagram the forces ha\e been dis Composed in a definite way. we must now correct for the effect of this assumption which had made possible the construction of the stress diagram. Step ." indicates bow the proper correction is made for the stresses in the vertical struts. The reason and method are ob\ ions. A similar correction should also l>e applied in the hori/ontal members. It is clear that the various pin points sustaining a load will partake of the hori/.ontal component of the force due to the inertia of that load. Not necessarily in the inverse ratio of their distanci s from that load, but in a way depending on the riifidity of the members through which this load is con- 'I to them. Thus, instead of having: The resultant!! of these systems are equal in all re- spects; but tin- second, more correct assumption would cause a more complicated str. s- di IUT.IIII. which would not show \irv different stresses in the longeron*. It seems ijnite proper to make these corrections afterwards if they are desired at all, when the m< tubers havi .ned and their degree of rigidity is known. In the ease of ohlicjiie members, both a vertical and hori/ontal correction must be applied. Tims, in spite of the efforts of this method to give close accuracy, there is still room for the engineer to make sunn- corrections baaed on good judgment, but these corrections mid not IM- made in most ordinary canes. The present example illustrates the application of the method proposed here, a small variable angle of inei- ih in e biplane being assumed. The apportioning of loads to pin points is done as follows: (I) KntfiHf and Vroprllrr I Hi Ibs. This load will be considered us applied at the vertex of a small triangular truss which is in fact supplied by the engine crankcase. Thus: (2) Tank,, Fuel and Oil. ' 7 Here joint a must take I 20 X U 14.3 Ibs. 14 SOX 4 b must take - =5.7 Ibs. (3) H'hrelt * t Ibs. These rest direetlv on the ground and impose no stresses If strut a was elastic and strut 6 rigid we would have: . . (i) H'inffi l-.'.'i Ibs. As in the ease of the power pant, these are taken as concentrated at the joints of their Mip|>orting truss. a f / (3) Pilot 160 Ibs. 1 1 ;r, + 0.3 n\ 10 ;r, 1 1.3 n\ = o These moment equations show that we have an indeter- minate case as could be expected, since there is more than 3 points of support, all we can do ' to eliminate one of the terms in a judicious manner. 282 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING 14'-*- By setting for example W l =W 2 X 16/14 We have then three equations containing 3 unknowns, as follows: (1) 14 X 16 rF t + 9.5 W 3 16 W 2 11.5 = 14 (2) 6V 16 W z + 6W 2 16W 3 15W 4 = Q 14 (3) W, 16/14 + JV 2 + W s + W t = 160 ~OW 2 9.5 W s 1 1.5 W 4 = 12.685 Wv 16 W s 15 W t = 2.142 W 2 + W 3 +W 4 = 160 + 9.5 11.5 16 15 16 1 1 9.5 11.5 12.685 16 15 2.142 1 1 22800 29400 52200 ~- 53.8 Ibs. 146 305 123 90.9 16 X 53.8 - = 61.5 Ibs. Check 11.5 12.68 15 2.142 160 1 96.9 32.15 23300 96.9 . = 24.1 libs. 9.5 12.68 16 2.142 1 160 19250 96.9 96.9 = 19.9 Ibs. 19.9 = Wi 24.1 = W a 61.5 = JPPj 53.8 = W 2 Total 159.3 HORIZQNTHL FuNICULRR PoLV&ON -.OCATINb CcMTEKOr M/133 or AfROPLflNF ;. 1 . LOADING DIAGRAM Srrixv> location of M*t (xJI)rd(rfd In Sir, u fUnft. IH A HOfttZONTAL I INC SCRLE OF DIMENSIONS i l* = 20" FORCE SC/JLE |" = 100 Ibs / VERTICBL FUNICUIBR PotxcoN Locflrtnft CENTER OF MAIS or ACROPLANC IN A ICRTItni lIMe ^ ^ SCALE or DIMENSIONS : I -.- ZO FORCE JCRLE: = lOOlbJ. J..f>Mhc M.C. C U- '. STRESS SHOWING LOCATION am Or GrlftvlIY Rt5utTNT REACTION STRESSES m ncnaeicj DIMENSION Sem.i.-r=2o w FORCE SCflUE : |"=IM i MKTHODS I SKI) IN I 1M)1\(, 1 I SKI \(. I. STKKSM S 288 (6) Tall H'orkt 3() 11.-. 7" _L At tlii-. point it is interesting to study the retarding cll'cct of the rolling friction which lias been assumed. This force as scaled from the diagram is F= 1 IT ll.s. FMa since and ~T~ i ~~ ~ 15 - 8 mass /' 1 1 A Hetardation o = = ^ = 9.3 ./ 147 i also a = = . a = p = 9.8 rfi and J f in.p.h. at the instant of first contact with the ground: V = 58.6 ft./sec. and 5 = then - = c=17*0 and when the aeroplane has finally come to the V = O and and this figure is not an improhahle one for the machine n question, anil shows a capacity on the part of the landing gcnr to take care of rather rough ground without causing the machine to turn on its nose. If this figure u : > checked on the nYld. it would prove that the rolling friction has been correctly assumed. CHAPTER IX THEORY OF FLIGHT This elementary and clear definition of the principles of flight was prepared by the Aeroplane Engineering De- partment of the V S. Army, from lectures delivered at the Army School of Military Aeronautics at the Ohio State University. These lectures were given by Messrs. H. C. Lord, G. T. Standard, and W. A. Kmght. Investigating wind action - Constant values - Studying action of wind - Streamline shapes -Head resistance - Liff drift Md angle of attack - Suction on top of plane - Center of pressure - Cambered planes - Horizontal flight Engine power Power to climb Stability. In this age of mechanical flight everyone is interested in aeroplanes. But very few people, however, clearly grasp the underlying principles. The theory involved, nevertheless, may be demonstrated by simple experiments, so that the reader with only an elementary knowledge of mathematics and mechanics can understand. The simplest principle of aeroplane flight may be dem- onstrated by plunging the hand in water and trying to move it horizontally, after first slightly inclining the palm so as to meet, or attack, the fluid at a small angle. It will be noticed at once that although the hand remains very nearly horizontal, and though it is moved hori- zontally, the water exerts upon it a certain amount of pressure directed nearly vertically upwards and tending to lift the hand. This is a fair analogy to the principle underlying the flight of an aeroplane. The wings of the plane are set at a small angle, and the plane is pushed or pulled through the air by the pro- peller, which receives its power from the engine. The action of the air on the wings, inclined at an angle, tends to lift the plane just as the action of the water on the hand, inclined at a small angle, has a tendency to raise the hand out of the water. Investigating Wind Action A rough form of apparatus for studying laws of wind resistance is shown in Fig. 1. The arm E hinged at C carries a rectangular plane B. The adjustable weight D, supported by the arm F, is used to balance the pressure of the wind from the blower A. The pressure exerted on the plane B can then be measured by moving the weight D along the arm F until B floats with the wind. Professor Langley, in another experiment, proved that we can investigate the action of the wind upon various forms of surfaces as well by directing a current of air of known velocity against the surface held in position, and weighing the reactions, as we can by forcing the plane itself through still air. The special apparatus used was mounted on the end of a revolving arm driven by a steam engine as is shown in Fig. 2. The chronograph, a recording instrument, was used to measure the velocity or number of revolutions of. the table in a given time. By such a method as that shown in Fig. 1, and that of Professor Langley, it is easy to see that the laws of pres- sure and velocity can be determined readily. Methods such as these have been used in determining that the iciiiil resistance varies as the square of the velocity. In other words, if the velocity is doubled it follows that the resistance is increased four times, or if velocity is five times as great, the wind resistance is twenty-five times as large. FIG. 1 Elementary apparatus for studying laws of wind re- sistance Constant Values It would therefore seem to need no experimentation to prove that if we increase the surface B (Fig. 1) we would increase the pressure in direct proportion to the increase in surface area. Now if we were to increase both the velocity and the area of surface, we would increase the pressure proportionally to the product of the square of the velocity and the area of the surface. Thus if we were to raise the velocity of the air three times, the re- sistance would be increased nine times, and if we then doubled the surface we would double the resistance, which has already been increased nine times, making a total in- crease of eighteenfold. There is still another factor to take into consideration in calculating wind pressures, and that is the shape of the surface. To take that into account we must use what is called a constant, the value of which is determined by experiments for each particular shape of surface. 284 THKOHY OF KI.K.II I - 1'rof. I.murlry's apparatus for invi-stijratinjr wind ac- tion on various forms of sun Tin- following explanation will enable one to see very l.-arlv tin- meaning of the term constant and bow its able i-- determined. First let us explain the term formula which is merely :i si-ntence tersely expressed. To attempt make a study of flight without formulte would make it iry to express relations between <|uantities in long Mragraphs of words that could more readily be stated in iiniple equations. Thus if it were desired to state the ule that the quantity A multiplied by twiee the quantity 1 i- i qua! to ('. the formula representing this would be: AX 2B = C Jach letter or symbol in a formula represents some factor hat is substituted when its value is known. If A = 16, :nd H= I, then ('=128, since the rule interpreted eads: Hi X 8= 128. Derived and empirical n/iiatiom. The term equation imply means that the quantities on one side of the equal iliii are equivalent or equal to the quantities on the other iide. Equation* are of two kinds, derived and empirical. \ derived equation is susceptible to proof, by use of mathe- natical processes. An empirical equation is neither de- ivcd nor proven. It is merely a .statement of the results f experiment regardless of mathematical proof. In many branches of engineering, empirical formula- arc onstantly used, and in aviation the lack of a satisfactory u-ory of air flow makes empirical formula? based on xperimeiit most necessary. Kmpirical formula- are really mental averages. Tin i. mi . "iiitant can now be fully explained and it will In Men IIOH Ix-autifully it works out in a formula. It is often found necessary, especially in an rx|M-riiin ntal tit Id. to introduce numerical constants to balance the two sides of nn equation. For example, the pressure on a sur- 1 PROJECTED In. I - Illustrating of term " projrctr = Pressure S= Projected surface area K = Constant V 1 = Velocity squared The exact value of the constant K for any surface is determined experimentally by wind tunnel tests. So val- uable have wind tunnels proven for s i.-h determinations that several of the large aeroplane builders now have in- stalled them in their plants. In solving a problem it might ! known that the pres- sure I' \aries as the area of the surface and the velocity squared, but we could not express this relation in an equation capable of solution until a numerical value for K is determined for the particular sha|H- subjected to Un- wind pressure, such as the shape illustrated in Fig. S. Kach different shape of surface requires a different value for K, which can be determined cxjx rimcntally. The majority of formula- for air pressures involve con- stants, and the great advance in designing during the past two years may lie traced directly to the determinations by the aerodynamic laboratories, of better values of these constants, for use in empirical formula-. So when M. F.iffcl, or other men of authority, inform us that the con- stant K for a flat shape is .<><);(, we accept the value just as we do the report of a chemist who tells us the compo- sition of an alloy. Parasite Resistance A picture of a typical aeroplane is shown in Fig. 5. Notice that all the struts, wires, landing wheels and tin- fuselage or body offer resistance to passage through the air a resistance which must be overcome by the engine. The sum total of the separate resistances of all these I i'.. V K\|M-rim<*n HIT lift of inclined rrnt Mirfnrr in air cur- 286 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING H FIG. 5 Curtiss aeroplane, showing control surfaces parts is called the parasite resistance. This wastes power and so all such parts are carefully streamlined wherever possible. Note the wings or aerofoils, two on each side, one above and one below, and at the rear a vertical rudder R in front of which is a vertical fin V, and the horizontal fin H, the back part of which can be turned up or down by the pilot. The effect of this is to cause the machine to point up or down and thus change the angle at which the relative wind strikes the aerofoils. This change, as we will see, has much to do with the flying of the machine. Lift, Drift and Angle of Attack Thus far we have found a lot of things about an aero- plane which would tend to prevent its flying. Now let us study Fig. 4. Here we have a plane B fastened so that it makes a small angle with the direction of the wind from the blower A. The arm is hinged at C, and bal- anced by the weight D, so that when the movable weight W is pushed back to C the plane B will be slightly too heavy. When the blower A is started the plane B in- stantly lifts and the amount of this lift may be measured by the movable weight W. If we replaced this model Fio. 6 Illustrating how lift and drift result from the moving of an inclined surface in the direction of arrows by one exactly like it except that the plane B makes ; much smaller angle with the relative wind we would fine that the movable weight W would have to be much nearei C than before. This simple experiment proves the exist ence of a force which tends to lift the plane and furthei that this force is greater as the angle is increased. Tin; angle is called the angle of attack that the plane B make: with the air stream. The force which tends to raise th( plane is called the lift, and evidently its value must de' pend upon the profile of the plane, the velocity squared and the angle of attack. Besides the lift, there is another force which is dui to the plane's velocity through the air, called the drift This force is due to the fact that the plane itself offers resistance to forward motion through the air. In Fig. 6 A represents a bubble of air, BC a plane moving in the direction of the arrows. Now evidently one of two tilings must happen. Either the plane must force the bubble of air down or the bubble of air must force the plane up, This resistance that the bubble of air offers to being dis- placed, as we have seen, depends upon the square of the velocity with which it is forced out of the way. The total resistance offered by the bubble to the movement oi the plane may be represented by the force P acting al right angles to the surface of the plane. The horizontal and vertical components of P are represented by D and L, respectively. If we were to let the air on the surface have its way. il would push the surface upwards in the direction of I and backwards in the direction of D at the same time. So we put weight on the surface, enough to overcome the force L, and then quite logically call this force thj lift. And for D, we push against it, with the thrust from a propeller, and we call D the drift. This simple explanation enables us at once to state the reason why flight in heavier-than-air machines is possible. By pushing the inclined surface into the air with a hori- zontal force D, we create a pressure on the surface equal to P, the force of which D is the horizontal component. But by doing so we have also created the other component L, which is a lifting force, capable of carrying weights into the air. THKOHV OF FLIGHT _'H7 I'n.. ' \pparatiis proving existence (if lintli lift anil drift Consideration of tin's resolution into lift and drift at OIKT Indicate! that tin- characteristics to be sought for in a surface are great lift with a very small drift, so that for a minimum expenditure of power a maximum load carrying capacity is obtained. .lp /HI rut 11.1 nxi-d to prove fiiitence of lift and drift. An apparatus used to demonstrate the existence of these forces is shown in Fig. ~. The inclined plane B is fast- ened to the arm S hinged to the carriage C at the point F. The carriage rests on a glass plate I) and is shielded from the wind from the Mower II In the screen K. It I' I*.. s I >r\ ice for measuring comparative air pressures IHI upper and lower surfaces of an inclined plane u found that when the blower is started the plane B will lift and the carriage C moves slowly backward carry- ing the plane with it, thus proving the existence of lift and drift. The screen E is then removed and it is found that the carriage moves away very rapidly, thus showing the effect of the added head resistance due to the carriage Its, If. Suction on top of Plane Tin- Hat surface is seldom used for the aerofoils of an aeroplane. The following illustrations and explanation will help to show the reasons for not using it. The plane 1' (Fig. 8) has an opening at () connected to manometer M. while on the under side is a similar open- ing connected to the manometer X through the rubber tube T. When the blower is started the manometer .M shows .suction at the point O on the upper side of the plane and \ shows pressure on the under side of the plane. In other words, the plane is not only blown up, but it is sucked up as well. This is very effectively illustrated by n still simpler ex- periment. Fig. 9 shows the plane AB of heavy card- board to which is fastened a light strip of paper at the point A and left free at the point C. When the plain- is placed in a wind blowing in the direction of the arrows the paper is seen to be drawn up to the position AC' away from the plane AB. Experiments at Eiffel Laboratory. Fig. 10 shows the result of accurate measurements by M. F.iffel of the suc- tion on top of a plane and the pressure underneath. I-'ur- FIG. 9 Showing suction on top of inclined pi. UK- when exposed to wind current in direction of arrows ^vast/re Curve kr iower Surfoce I'n.. 10 Pressure diagram of upper and lower surfaces of inclined plane thermore, F.iffel has shown by recent experiments that when the angle of incidence of a flat plane is low. the value of the suction on the upper surface is considerably more than that of the pressure on the under surface. Thus in this case it is the upper side of the plane which contributes most towards the creation of the lift, a func- tion increasing as the angle grows smaller. This fact shows that the profile of the upper surface of a plane li is as much, if not more, importance from the standpoint of the value of lift than that of the under surface. Center of Pressure In Fig. 1, it is evident that the wind's force on the plane B could be entirely replaced by a single force act- ing at the center of the plane. The fact that this point would In- the center of the plane is due to the fact that the wind strikes the plane absolutely symmetrically. On an inclined plane, however, the action of the wind on the front or advancing edge of the plane is different from that on the rear or trailing edge of the plane; hence, we _>88 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING can no longer say that the center of pressure is at the change the position of the center of gravity by placing a small lead weight on the front edge. Then if the cor- ners at A and B, Fig. 13, are turned slightly upwards while the whole is given a lateral dihedral angle as shown geometrical center of the plane. The result of the double action of the air-current with pressure below and suction above, both unequally dis- tributed, is that the total reaction on the plane is ap- plied at a point C (Fig. 11) nearer to the leading edge A than to the trailing edge B. This point C is called the fLeac/ Weight C Fio. 11 In a flat plane, center of pressure C moves toward the leading edge A as the angle of incidence becomes smaller center of pressure of the plane. In a flat plane, C moves toward the forward edge at' wli.it our might call :i typ- ir:il win-; section. Noli- tin- difference in profile |.. tlir top anil liottoin surface,. Tlir i-lmril max In ilrliiiul as tlir straight lim- whirh is tangent to tlir unilrr surface of tlir arrnfuil si-rtinii, front ainl rrar. and the aiiifle of attai-k as tin angle hrtwrrn tin rrlatiir wind anil the rliord ot tin aerofoil. We may rile tin- following sim- )ilc expression for the lift and the drift: The Lift (10 = k t 8V The Drift (D) = L/r. I i... !' Sketch of typical wing section with aeronautical trrms iiuiii .iti-il '. film nt k, depends upon the shape of the aerofoil anil the angle of attack and must be determined experi- mentally. The <|iiantitv r, also determined experimen- tally, is railed the lift-drift ratio and measure-, the cffi- I'icncv of the aerofoil. CfiAHACTCf*l<3TtC ^SECT/ON AND L/ O VA.L UC^S -Ot 3t O< 3? 0020 03 , JH.Z O" / Yo/ Xw OS ^6 iV , 7-a- & /cr/r/2'/3r/4'/s'/6'/7'/a'/9'2a' AN&LC OF /NC/OENCe Of WIM6 CHORD MO. 17 ( urv.s .showing values of k L and Lift/Drift ratio for a typical winp section l-'i>t. 17 -nr, two rur\t, fnr m m-rofnil of th, sn-tioii shoHii. Th. tir,t riirx. j.i\rs the values of Ilir i|ii.intit\ k, for different nnjjles of attack, while tin serond ciirxc In \.ilur, of tin- litt drift ratio. 1 or i \ -niipli . sup|x>se that an aeroplane with aerofoils of the Upr shown, lifting surfaer i!ii si), ft., is Hying at an angle of attn. k of II drg., and with a \elo-ity of 7<> m. p. h. \\'lrit will l.c the lift and the drift ? I'roni the eh.-irt. Fig. 17. we nnd that for this t\p. of plan, and angle of attack k L (UMIiiH and r II, h. nee. L = k. SVJ = O.OOJ8 XOX (70)s = 8>J lb. I D = = =73 II*. r 11 If now we elian^r the angle of attack to ;fl ., d< ^.. krep- illg tile surface and velocity the same, \vr tind from the ehart that k L = 0.0014 and T=- 18.5, h< D Horizontal Flight For horizontal flight the lift produced Ity the machine's velocity must nt all times exactly eijual its weight. 1 if the lift were less than the weight, the pl.-mc would fall, while if the lift were greater than the weight, the machine would In-gin to climh. \\'e therefore can replace the lift l.y the weight \V. Then we would have for hori- zontal flight : Weight (\V) k. M and the drift (D) =\\ r For example, a given aeroplane weigh, (with load ) IK(K) ll>s. Its aerofoils arc of the type illustrated and the lifting surface i, 120 aq. ft. What will 1 it, v. locity for horizontal flight at an angle of attack of 12 leg. ? From the ehart, Fig. 17. we find that for this type of plain- and angle of attaek. kL= <>.<>< i-J!), whence, ' I. = W = k L SV= or 1,800 = 0.00i9 X 1 X V trnns|x>sinp, V' = ura .0029 X 120 hrncr, V= V*,17i = 7i m.p.h. If now we reduce the ani'le of attack to 5 deg., the ehart. Fig. 17. shows that k,_ bcronn s (i. (Mil 7.1. whence. 1,800 = 0.00173 X liO X \ transposing, V = - O.(l017i X HO HCIKT, V = VH^'i or 93 + m.p.h. The above example ill-istrates this important principle that, since a machine in horizontal flight, except for a slight loss due to consumption of gasolene, main) '.in, a constant weight and a constant surface and since k j_ for a given plane depends solely upon the angle of attaek, the 290 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING velocity for horizontal flight is completely determined when we know the angle of attack. Now since the pilot can control the angle of attack by means of his elevators he can control the velocity for horizontal flight. Fig. 18 shows four different positions of the plane cor- responding to four different angles of attack. In each case the machine is flying horizontally, though at first sight one might think that in position 4 the machine was climbing. FIG. 18 FOUR POSITIONS FOR FLIGHT (1) Minimum angle. This is the smallest angle at which hori- zontal flight can be maintained for a given power, area of surface, and total weight. The minimum angle gives the maximum hori- zontal flight velocity at low altitude. Note that the propeller axis is inclined slightly downwards when flying at this angle., (-2) Optimum anyle. This is the angle at which the lift-drift ratio is highest. In modern airplanes the propeller axis is gen- erally horizontal at the optimum angle, as shown at (^) in the above figure. Note that in the position shown the velocity of the airplane will be less than when flying at the minimum angle. The effective area of wings and angle of incidence for the opti- mum angle are such as to secure a slight climbing tendency at low altitude. (3) Rest climbing angle. This angle is a compromise be- tween the optimum and maximum angles. Modern airplanes are designed with a compromise between climb and horizontal veloc- ity. At this angle the difference between the power developed and the power required is a maximum, hence the best climb is obtained at this angle. See Fig. 22. (4) Maximum angle. This is the greatest angle at which horizontal flight can be maintained for a given power, area of surface and total weight. If the angle is increased over this maximum, the lift diminishes and the machine falls. It would seem at first that we have entirely neglected the engine, especially as there is a general impression that the velocity of a machine depends upon the power of the engine, while as a matter of fact the form of wing sections together with the plane's dimensions are equally, if not more, important. In the preceding discussion we have simply assumed that the engine had the necessary power to maintain the plane at such a velocity as was determined by that angle of attack at which the pilot drives the machine. Engine Power The power of any engine is measured by the velocity at which it can move a body against a given resistance, and its unit, the horsepower, may be defined as the power required to lift one pound 33,000 ft. in one minute or 375 miles in one hour, or the power required to lift 375 pounds one mile in one hour. We must therefore multiply the total resistance offered to the aeroplane, which consists of the drift plus the para- site resistance multiplied by the velocity of the machine, .U 18 /6 14 8 6 4 a ** . / N, S" --" f fcw^. V h \ ^ ^ 1 * s s^ X ~/ ^, 1 ^x ^ / \ / \ 7 \ ' K, / / 1 .. / / / .004 003 .002 .001 4 6 6 /0 12 /4 /6 /d Anq/e of/ncic/ence FIG. 19 Value of k L and Lift/Drift ratio for a given niachin and divide the result by 375 to get the horsepower re quired. Or, written as a formula: (Drift + Parasite Resistance) X Velocity = Horsepower 375 From the above expression for horsepower, it will b noted that since the drift for a given machine depend solely upon the angle of attack, and the parasite resist ance depends upon the square of the velocity, which i turn depends upon the angle of attack, we may state tha for a given machine with its load, the horsepower is com pletely determined when we know the angle of attack a which the machine flies. Fig. 19 corresponds for the entire machine to Fig. 1 for the aerofoil itself and gives the value of k L for a give machine, as well as the lift-drift ratio. Fig. 20 gives in the heavy curve the power require to drive the machine at the angles of attack marked o: iUU 30 50 70 \ 60 30 20 I ''I '/ V ^ -0 _ r\ -1 =>A f/ ^ Iff W '. t W_ It s ^ W tf . fc o ( *^ 1 t r / , ^ I /i /)/ )/ J / | rl fit) '->- /p /(. o t -) ~r f.. f. 1 ~y ^- -^ <-. -,* t/ fa ^.. n- % ^ .. - ,i mm 1 ffu 40 45 60 tf 60 65 7O 75 60 85 >peed 'in rr>//e<-r hour gixcn at tin- bottom. The otlii-r set of curxes. four of tin-Ill dashed .'iliil one ;i li^ht line, unc (lie power dc livercd to the machine by the engine through the pro- pellcr. The latter would I e straight hori/.ontal lines were it not for the tact that the efficiency of the- propeller varies with the xdocity of the aeroplane. The orclinates as show n on the left side of the diagram correspond to horsepower. I. (I us .(insider the case where the cnuinc is making l.i ><> r.p.ni. It will lie seen that if the pilot changes his clcxators so as to My with an angle of attack of a little less than 1 detr., or of a velocity of about 82.5 m.p.h.. he 30" Fio. .'I Showing rapid changes in wind velocity in short spaces of Him- will be using every particle of power that his engine can deliver at that speed. Any slight decrease in the angle of attack will cause him to go down probably in a nose dive. As he increases the angle of attack we come to a point where the distance between the two curves, power delivered and power required, is the greatest. Here we will have the greatest excess of power over that used for horizontal flight, all of which can be used in climbing, i ! that point will be the position for maximum rate of climb. It is indicated by the vertical dash line marked m,,.,imum rlimb at an angle of attack of a little less than 6 deg. or a velocity of a little over 55 m.p.h. Increas- ing his angle of attack still further, or at about 8 deg., which is the lowest point on the curve, where the horse- power required for horizontal flight is only 30, we get a point of most i ..inoinic.il flight. Then, as we decrease the angle of attack, tin- power n quired rises rapidly until at Hi m.p.h. the two curves cross again and any iner. IM in the angle of attack would cause the machine to stall in I!K sense of going down, which might take the form of either a nosi- div . or tail slip. It is well to compare this with Fig. 18. It is also interesting to compare this with l-'ig. 21, taken from I.angley's Thr Stored Knrri/fi of the It'inil, and which illustrates the rapid changes in the velocity of the wind occurring in short intervals of time. The xertical lines represent spaces of one minute and the hori- zontal lines wind speeds differing by I m.p.h. It will be noticed that between 32 and 21 min. the wind fell from about 37 m.p.h. to 12 m.p.h. and rose again to :ili/.ing surface some distance hack from the main surface and set at a lesser angle of incidence than the main surface. Such a stabilizer is a necessary feature of all modern aeroplanes. Fig. 27 shows two such surfaces in tandem, thus forming an elementary aeroplane. Consider the aeroplane to be traveling; horizontally with the angle of incidence of the main surfaces fi dcg. and the rear one-third of this, or 2 (I. ^. Now supposing a sudden gust pitches the plane into some such position as shown in the lower part of the dia- :n. The .ingle of incidence of both surfaces is now reduced say 1 deg., the main surface being at a ' deg. angle and the rear surface at 1 deg. In other words, the main surface has lost only about 17 |HT cent, of its angle of incidence, whereas the stabilizer has lost M per cent. Consequently the stabilizer has lost more of its lift than the main surface, and it therefore must fall relative to the position of the main surface, bringing the combina- tion back into normal position again. On the other hand, if the front of the plane is suddenly forced up. the sta- bilizing surface receives a relatively greater increase in angle of incidence than the main surface, hence relatively greater increase in lift, pausing the back end of the plane to !>< brought up until the combination again is normal. I.alrral ttahility. This stability is necessary to pre- vi nt the machine from rolling about its horizontal axis. It is difficult to secure, but is often promoted by having a slight lateral dihedral angle between the upper wing urfaccs. as .shown in Fig. 28. Should the aeroplane sud- dcnly be tip|>cd to one side, in the position shown to the right of the diagram, the planes on the (low n side In . om< more nearly hori/ontal, whereas, those on the other side assume an angle s'lll greater than they had when Hying normally. Thus, the effective projected lifting snrl tin side A is increased and that on side M is deer bringing the plane back to its normal lateral position Other features arc introduced to aid lateral staliility, such as "wash in" on the left side to give this side slightly more lifting ability to compensate for the tori|iic of the propeller. Dirrclional *tal>ility. Such stability aids in keeping the plane on its course. In order to prevent yawing with every gust of wind, the vertical tail fins present on nearly all modern planes are used. Referring to Fig. .'! A. sup pose a sudden gust of wind to deflect the aeroplane from its normal course A so that the nose points off the course to the pilot's left, as indicated by the dotted lines in position B. This swings the tail around to the right so that the right side of the vertical fin presents a flat sur- face to the wind pressure resulting from the tendency of the machine still to move forward in the direction A, due to its inertia, even though it is temporarily pointing in direction H. A moment with arm r is thus set up. which tends to swing the plane back on its vertical axis until the fin is again parallel to the direction of the relative wind. The action is similar to that of a wind vane, tin- vertical fin of which always keeps it [minting in the di- rection of the wind. Fio. 29 Diagram to show action of vertical fin in preserving directional stahilitv CHAPTER X SHIPPING, UNLOADING AND ASSEMBLING Shipping instructions Marking boxes Methods of shippping Railroad cars used Unloading Method of load- ing on truck Tools required Unloading from truck Unloading uncrated machines Opening boxes As- sembling Fuselage and landing gear Center panel and wings. Shipping instructions. Boxes in which aeroplanes or parts thereof are shipped should be marked with the fol- lowing: Destination, or name and address of consignee in full. Sender's name. Weight of box (gross, net and tare). Cubic contents (or length, width and height). Box and shipment number. Hoisting center. " This side up." Methods of shipping machines. Machines are shipped either by loading in a railroad car without crating, or by crating in two boxes. In the latter case the wings, cen- ter section panel, tail surfaces, landing gear and propeller are removed from the fuselage, and the fuselage, landing gear, propeller and radiator are packed securely in the fuselage box. The other parts are packed in the panel box. All aerofoil sections are stood on their entering edges and securely padded to protect their coverings. Struts are stood on end. If the machine is not to be crated only the following parts are removed wings, center section panel, tail sur- faces and propeller. The fuselage is loaded into the rail- road car and allowed to rest on the landing gear. The latter should be blocked up, however, to take the load off the tires of the landing gear wheels and off the shock absorbers. The fuselage must of course be securely fast- ened in the car to prevent movement in any direction. The wings and other separate parts are crated against the sides of the car. The wings are secured with their entering wedges down and carefully padded to prevent damage. Railroad cars used for transportation.- If possible open end or automobile cars are used for transportation of aeroplanes. Sometimes with crated machines gondola cars are used, and with uncrated machines, ordinary box cars having no end doors. In the latter case, however, it is necessary that the side doors of the railroad car be as wide as possible, to allow working the fuselage in and out without damage. For transporting machines (either crated or uncrated) from the railroad, a flat top truck is used. If the truck is short it will be necessary to use a trailer to support the overhang of the boxes. Unloading Method of loading on truck. Before unloading a ma- chine, everything in the railroad car should be inspected 294 for loss or damage. If everything is O. K. proceed with the unloading, but if any loss or damage is discovered re- port fully at once to the receiving officer and await his instructions before doing anything further. The tools required for removal of aeroplane boxes from the railroad car are: 1 axe or hatchet, 2 crow bars, 6 or 8 rollers and 100 ft. of 1 in. rope. The cleats holding the boxes to the car floor are first removed with the axe and crow bars, and the panel box removed from the car. If the fuselage box is not marked to show which is the front end it should be lifted slightly, if possible, first at one end and then at the other, to de- termine which is the engine end. This end, being the heavier, should come out first if possible. The truck is backed up to the door of the car, rollers are placed under the fuselage box and it is then rolled out onto the truck. The rope is now used to fasten the box to the truck. After this is done the truck is moved forward slowly and the box is thus pulled out of the car. If a trailer is to be used it should be placed under the box before the latter is taken all the way out of the car. When taking the fuselage out tail end first, the same methods are used, except that the light end is blocked up when removed from the car and a truck is put under the heavy end. When moving along roads care should be taken to go slowly over rough places, tracks and bad crossings. It is also a good policy to have a man on each side of the box to watch the lashings and see that nothing comes loose. Panel Box The wing box (or panel box) is removed from the car in the same manner as the fuselage box. Unloading boxes from truck. For this work 2 planks about 2 in. x 12 in. x 12 ft. long should be used. These should be fastened to the end of the truck with one end resting on the ground, so that they will act as skids. The tail end of the fuselage box is depressed until it rests on the ground, then by moving the truck forward carefully the box will slide down the planks onto the ground. Unloading uncrated machines. In this case all of the smaller parts should be removed first. Then the cleats and ropes are removed which hold the machine in the car. Two long planks are placed from the door of the car down to the ground and are used to roll the machine out of the car. Opening boxes. A screw driver and bit brace should NU r\I.()Al)IN(. \\D ASSEMBLING !>< used to ri-moxc tin sen -ws in the tn|i. sides .uid i -nils of the lxi\. Tin- top i- removed tirst. then one side. AH smaller parts nt tin iii.-ifliinr should In- t;ikrn out. after which tin- remaining side of tin- lm\ is removed, and lastly tin i mis. /> ^inl'liiii/ ii in in- lii in-. Tin- landing gear shoidil In- put on first. To do this tin- fuselage must In- raised hv our of to ini-tliods. Tin- first is by cliain falls or Murk and tackle. Tin ro|n- slinu should In passnl iindrr the engine sill just to (In- rear of the nose plate. Tin- tail of tin- inai-liiin- is allowed to rest on tin- tail skid while the nose is raised. The second method is by shims and blocking. This latter method is the most common hei-.-iuse chain falls are not always a\ ail-iMc. l-'.nutigli Mocks .should In- secured to raise the fuselage high enough to slip the 1 -iiiilin^ year underneath. The tail is tirst raised by J men and Mocks are placed under Station 5 or the rear wini; section strut. The blocking must be directly below the strut and must have padding upon it. Then the tail is depressed and another block is put under the forward wing strut. This operation is then repeated until the fuselajjc is hitrh enough for the landing gear when the ma- i-liine is blocked under nose and tail and the other blocks tour men arc all that xhould br n-(|uircd for this second method. Assembling Wing* r the landing grar is nssemMi d the center s. pin. I should be attached and approximately lined up. Then tin wind's .., rt - assembled. There are two methods for il.,in- this; one i* to put on the top plains, place sup purls under the outer edges, then put in struts and luwei planes and connect up the wires. The other method is to assemble the wings completely while on the ground. \\ Mitts are stoxl on their entering nine, struts are put in and wires tightened up to hold the wing irrtioiis together. Then tin- wings are attached to fuselage by turning them over and attaching the top wing tirst. then the lower wing. One side of the machine must IK- sup|xirted until the oppo- site set of wings is attached. After wings arc all at- tached, then the tail surfaces should be assembled to the body. The horizontal stabilizer should go on first, then the vertical fin. rudder and elevators in the order named. On some machines the elevators will have to be put on before the rudder. After everything i* assembled the machine is put in alignment. CHAPTER XI RIGGING Fuselage Construction Longerons Struts Fuselage covering Monococoque Landing gear Struts - Bridge Axle box or saddle Axle and casing Wheels Tail skid Shock absorber Wing skids Pon- toons on seaplanes Flying boat hull Wing construction Front and rear spars Ribs Cap strip Nose strip Stringers Sidewalk Struts Wire Bracing Wing covering Dope Inspection windows - wires and terminal splices Aircraft wire Strand Aircraft cord or cable Terminals and splices Solder ing Turnbuckles Locking devices. Rigging deals with the erection, alignment, adjustment, repair and care of aeroplanes. Aeroplanes are of light skeleton construction with parts largely held together witli adjustable tie wires, hence they easily can be distorted or their adjustment ruined by care- less or improper rigging. The efficiency, controllability, general airworthiness and safety of machine and pilot therefore depend very largely upon the skill and con- scientiousness of the rigger. For purposes of description the aeroplane may be di- vided roughly into three parts (exclusive of the power plant). These are the body or fuselage, the wings or aerofoils and the landing gear. The fuselage is the main structural unit of the aero- plane. It provides a support and housing for the power plant, contains the cockpit for the pilot, and the instru- ments and control mechanism. The rear end of the fuse- lage carries the rudder, elevators, stabilizing fins and the tail skid. The wings or aerofoils are attached to the fuselage through suitable hinged connections or brackets and the fuselage is supported by the wings when the ma- chine is in the air. Conversely the wings are supported from the fuselage when the aeroplane is on the ground, as in that case the whole weight of the machine is sup- ported by the landing gear and the tail skid, both of which are attached under the fuselage. The body or fuselage is of trussed construction, a form which gives great strength and rigidity for a given weight of material. Parts assembled together in the form of a truss are spoken of as members. Those which take a thrust only are called compression members, while those resisting a pull are known as tension members. Other members may be either tension or compression members, depending on how the load or force is applied to them at any given time. There are also members subject to a shearing stress and others to cross-bending or compound stresses. The fuselage is usually constructed witli four main lon- gitudinal members running the full length. These are called longerons. They are separated at intervals by compression members termed struts. The whole struc- ture is in turn tied together and braced by means of diagonal wires, fitted with turnbuckles for adjustment, which go under the general name of wire bracing or stay wires. Stay wires in certain parts of an aeroplane are desig- 296 nated as flying, ground, drift, anti-drift, etc. These will be considered later. That part of the surface of the fuselage which is bounded by two struts and two of the longerons is known as a panel. The points at which the struts join the longerons are called panel points or stations. The cu- bical space enclosed by eight struts and the four longerons is called a bay. Some makers, Curtiss for instance, num- ber the stations in the fuselage from front to rear call- ing the extreme front station No. 1. Others, such as the Standard, number these stations from the rear toward the front, calling the tail post zero. The longerons are made of well-seasoned, straight- grained ash*. They are curved inward toward the front end and usually terminate in a stamped steel nose plate. This is true particularly of aeroplanes equipped with en- gines of the revolving cylinder type. The nose plate is stamped from plate steel about .10 in. in thickness. This plate not only ties the longerons together at the front end of the fuselage, but supports one end of the sills on which the engine rests. In some types of planes it also forms a bracket for supporting the radiator. In other types of aeroplanes the longerons may terminate at the front end of the fuselage in an open frame which forms the support for the radiator and also supports the front ends of the engine bearers or sills. The two upper and the two lower longerons are brought together in pairs one above the other at the rear end of the fuselage, and are joined to the tail post or vertical hinge post on which the rudder is mounted. Lightened Construction In order to lighten the construction of the fuselage as much as possible, the rear portions of the longerons are often cut out to an I section and spruce is often substi- tuted for ash for the rear half, suitable splices strength- ened with fish plates being used wherever joints are made in the longerons. It is possible to lighten the rear por- tion of the fuselage in this way for the reason that this part of the body does not support as much weight or undergo as severe stresses as the forward portion. In a machine of neutral tail lift (one in which the rear horizontal stabilizers are set at such an angle that they barely sustain the weight of the rear portion of the ma- chine when flying horizontally in the air) the stresses in the longerons are exactly the opposite when the machin RIGGING -".'7 Mum inj; priiicipul piirt.s of fuwlgr is in tli. air In those obtaining on the ground. \Vln-n thr urn-bine i, .it rest mi the ground it is supported near the front ami n ar .mis of the fuselage liy the landing gear anil the tail skid. This method of support proiluees ten- sion in the lower longerons and compression in the upper. When in tin- air the niai-hine is supported by the wings which arc attached to the fuselage at the center whin ion. The system of supports, trusses and stay wires lictwccn the upper and lower wings transfers most of the .support from the wings to the center panel seetion of the upper wing. This results in tension in the upper lonyi runs and compression in the lower. The fuselage struts are usually made of spruce, al- though ash is sometimes used. The struts are joined to the longerons by means of metal elips. The eonstruetion of the clips, which arc usually Lent in I" shape, is such that each forms a partial socket for receiving the end of a strut or struts. In general, struts are subjected to compression only. For this reason spruce is the favorite wood for struts as it is very strong along the grain in tension or compression. The strength of steel, weight for weight, would have to be 18O.OOO Ibs. per square inch to eijual spruce for this purpose. Spruce is not. however, very strong across the grain and splits readily, henee it is not a great favorite for parts subject to shearing or cross-bending stresses. On account of the liability of spruce to splitting, the ends of the struts are sometimes encased iii copper ferrules or bands. This prevents crush- ing, splitting and chafing. Compression Struts When a member is subjected to a compression force it tends to bend or buckle in the center. To resist this tend- ency, struts subject to compression stress arc made larger in the center than at the ends. Ash i> selected for the longerons because it is strong for its weight (about 38 Ibs. per cu. ft.), very elastic and can be obtained in long, straight-grained pieces free from defects. It is strong across the grain so that it is able to resist the compression due to clips and struts attached at \arious points on the longerons. The metal dips in which the ends of the struts are mounted are punched from sheet steel, then pressed to form. They are frequently made of two or three sep aratc pieces which are then electrically spot-welded to gether. They are made of .*8 to .:! per cent, carlton steel. The lower cross mcml>crs of the fuselage at stations .( and \. numbered from the front, terminate in a half hinge to which the lower wing sections arc attached on either side of the fuselage. These cross-members ser\e as com- pression members when a machine is on the ground, but when it is in the air they become tension member*. Engine Bearers The engine bearers arc made of spruce with a strip of ash glued on top and bottom. They are further protected against crushing, at points where the engine supporting arms rest on the sills or stringers, by means of a copper hand. There is usually a fire screen between the engine space and the cockpit. This is to prevent injury to the pilot so far as possible in case of a back fire or fire in tin- engine space. The seat rails are short longitudinal members forming supports for the pilot's and observer's seats. These rails, which arc mounted on either side of the fuselage, are at taehed to adjacent vertical struts at the proper distance aloic the lower longerons. The rudder bar is a cross bar pivoted at its center and mounted a short distance above the floor of the fuselage. It is used to control the vertical rudder and is operated by the pilot's feet. Ordinarily the ends of the rudder bar project through the sides of the fuselage, working in suitable slots cut for them, and the rudder wires are at- tached to the ends of the rudder bar outside of the fuse- lage. In machines fitted with dual controls there arc. of course, two rudder bars and these are fastened together by means of wires connecting their outer ends. The rear of the two rudder bars is then connected to the vertical rudder in the usual way. Wing section struts are vertical or diagonal struts mounted above the fuselage and attached by means of strut sockets to the upper longerons. The wing section 298 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING struts are used to support the center wing panel when the machine is on the ground and when in the air they help to support the fuselage from the center panel, the latter being supported partly by the upper wing sections which are attached on either side of it and partly by the lower wing sections which are braced to the upper sections and also attached on either side of the fuselage as pre- viously described. The strut sockets in which the lower ends of the wing section struts are mounted consist of U-shaped steel plates firmly attached to the upper longeron. The wing section struts are mounted between the side walls of the socket, usually by means of a heavy through-bolt. Standard Fuselage Construction The type of fuselage just described, which is of wood and metal construction, may be said to represent standard practice in this country at the present time. There are, however, other types of construction, such as the all-steel fuselage. In this the shape of the members and the meth- ods of joining them follow closely standard methods in structural steel work. It is claimed for the all-steel con- struction that it is lighter for a given size machine than the wood and metal or composite construction. The fuselage is usually covered either with canvas or linen material similar to that used for wing coverings or else with very thin panels of veneered wood. In the former case the longerons, struts and braces must carry all the weight and take up all the stresses to which the fuselage is subjected, but when a veneered wood covering is used, it contributes materially to the strength of the fuselage, consequently the framework of the latter may be made lighter. There are also fuselages of the monocoque type in which the strength is obtained not by a truss construction, but by the form and nature of the outer shell itself, this being made up of alternate layers of thin wood veneering and cloth until the desired thickness and strength are ob- tained. The various layers of wood veneering are laid with the grain running in different directions in the differ- ent layers. This type of shell or body, which is usually somewhat fish-shaped, possesses the necessary strength and elasticity without the system of struts and tie wires common to the ordinary or trussed type of fuselage. The monocoque construction possesses one marked disadvan- tage, however, and that is that it is very hard to repair in case of slight damage. It may be added that the monocoque or laminated wood construction is far more common in foreign countries, par- ticularly France and Germany, than in the United States. Landing Gear The landing gear is an assembly of struts, fittings, axle, wheels, shock absorbers and bracing wires whose function is to enable the machine to rise from and land on the ground and to furnish the main support of the machine when resting on the ground. The struts of the landing gear are of streamline shape to reduce the resistance when flying. They are usually made of well-seasoned, straight-grained ash or spruce. Very often they are further strengthened by several wrap- pings of linen twine. The struts with their fittings con- stitute important members and should be carefully exam- ined at frequent intervals. Failure or collapse of these struts would be almost certain to cause a serious accident when landing. These struts are attached to the lower side of the fuse- lage, usually to the lower longerons themselves by means of metal socket fittings. The lower ends of the struts on each side of the landing gear are joined together by a metal bridge. This bridge not only serves to tie the lower ends of the struts together, but it also forms a yoke or housing in which the axle box plays up and down. The bridge is made of a steel stamping or drop forging. The axle box may be in the form of a whole box or a half box. When it is in the form of a half box it is gen- erally called a saddle. Its purpose is to support the axle and to guide its vertical motion in the bridge. The saddle may be either of bronze or aluminum. It is held in its place in the bridge by a wrapping of elastic cord, which consists of a number of strands or bands of rubber bunched together and enclosed in a loosely-braided cover- ing. The assembly of the saddle, bridge and elastic cords : s called the shock absorber. The axle is made of steel tubing and is enclosed, be- tween the bridges connecting the pairs of struts, in an axle casing. This is made of wood, or sheet metal, built around the axle itself and is of streamline shape or sec- tion to reduce air resistance. The wheels are the ordinary type of wire wheels of rather small diameter and usually fitted with pneumatic tires. They do not, however, ordinarily run on ball bear- ings, as a slight amount of friction in the wheel bearings is of little or no consequence when leaving the ground at the commencement of a flight, and it assists somewhat in bringing the machine to a stop without going too far after alighting. The sides of the wheels are covered with linen cloth discs to decrease air resistance. Not all landing gears are like the one described, but this may be taken as standard practice. Some are pro- vided with a skid or a single wheel projecting ahead of and above the main wheels for the purpose of preventing the machine from taking a header or nosing into the ground on landing, in case it strikes the ground at too sharp an angle. Other minor details of construction will be noted, too, on different types of machines, particularly in the construction of the shock absorbers. The tail skid is a skid or arm projecting below the fuse- lage near its rear end. The purpose of the tail skid is twofold; first, to support the rear end of the aeroplane when on the ground or in landing, and prevent damage to the rudder and elevators and their controls, and secondly, to act as a drag or brake to assist in bringing the machine to a stop when landing. The tail skid is frequently hinged or pivoted where it is attached to the lower longerons and its upper end, extending above the pivotal point, fitted with rubber cords similar to those used in the shock ab- sorbers on the axle of the landing gear. This construc- tion acts the same way as the shock absorber and prevents damage to the empannage and rear portion of the fuselage when landing. Aeroplanes are often fitted with wing skids which con- sist of small auxiliarv skids under the outer ends of each RIGGING MO /Vase DrtniU of wing construction lower wing. These skids ordinarily do not come into ;u-tion -ind an- only pro\ ided to prevent damage to the outer win^s in alighting on rough ground or in case a sudden side gust of wind should tend to upset the machine when alighting or rising. Landing Gear of Seaplanes : 'lanes and flying boats are of course fitted with entirely different types of landing gear from that de- scribed. Seaplanes are fitted with pontoons or floats suit- able for arising from and alighting on the water. I'sually there are one or two main pontoons under the forward section of the fuselage, these corresponding roughly to I lie main landing gear of the aeroplane. There is also a smaller pontoon mounted under the rear end of the fuse- H| one under the outer end of each wing to prc\ent the wings dipping or the whole machine upsetting in rough water. The flying boat is so constructed that the whole fuselage i> in the shape of a boat and the whole machine is therefore supported on the fuselage when resting on tier and when alighting and rising from the water. The Hying boat is also usually fitted with small auxiliary pontoons under the outer edge of the wings to keep the machine steady in rough water. Standard Wing Construction The main members running the full length of the wing are called the spars. They are usually spoken of as front and rear spars. Sometimes the front spar is called the main spar. The cross members joining the spars together are called rilis. There are two kinds of these, compression ril's and the web ribs. The function of the web ribs is men h in support the linen covering of the wings and ist the lifting force of the air, due to the forward motion of the aeroplane. There is not much end pres- igainst these ril>s. therefore, the central portion is cut out for the sake of lightening them. The function of inprcssion rihs is not only to resist the lifting force of the air, but also to take the thrust due to the star w ires. The ribs are not continuous, that is, they do not pass through the spars. The ribs are made in three sections, the nose section, center section and tail section. The nose section of a rih is the section which projects forward of the front or main spar. The renter section is the section between the front and rear spars. The tail .section of the rih is that which projects to the rear of the rear spar. Tin' nose sections and tail sections are sometimes called nose rihs and tail rihs and are also frequently .s|mkcn of as nose webs and tail webs, because they are cut out to web form. These rib sections are not, of course, called upon to stand compression stresses, as these stresses are all centered in or taken through the front and rear spa- A thin strip of wood running from the nose weh across the spars to the rear end of the tail webs (lengthwise of the aeroplane itself) and serving to bind all the wing parts or rihs together, is called the cap strip. There is top cap strip and a bottom cap strip on each set of rib*. Entering and Trailing Edges The front edge of the wing section which is the part carrying the nose webs or nose ribs is called the entering edge of the wing. The rear edge of the wing is known as the trailing edge. The nose webs are tied together by a strip of spruce running full length of the wing or crosswise of the aero- plane itself. This strip forms the leading edge of the wing and is called the nose strip. From the nose strip to the front or main spar, on the upper side of the wing, there is a covering of thin laminated wood called the nose covering. Its purpose is to reinforce the covering fabric as it is at this point that the effect of wind pressure due to velocity is most severe. Secondary nose ribs are placed between each pair of full rihs to give additional support to the nose covering. There are usually two rod-like members running from end to end of the wing through the central part of the ;joo TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING ribs. These are called stringers and are used for the purpose of giving lateral stiffness to the ribs. The trailing edge of the wing is made of thin flattened steel tubing attached to the tail webs by metal clips. The spars are continuous throughout their length. Fur- thermore, they have reinforcements of wood at the points where the interplane struts connecting the upper and lower wings are attached. Steel bearing plates are bolted to the wing spars at these points. The bolts attaching these bearing plates to the wing spars do not pass through the spars themselves, but through the reinforcements. This is to avoid weakening the spars. Nearly all wood used in wing construction is spruce, with the exception of the nose covering which is made of bircli or gum wood, the web ribs, which are made of lam- inated wood, and small quantities of pine or other woods in the sidewalk and other unimportant places. The sidewalk is a boxed-in or wood-covered portion of the inner end of the lower wing. It furnishes a solid footing for the pilot or observer when entering or leaving the cockpit and for mechanics working around the engine, guns, instruments, control mechanism, etc. Steel hinge pieces are bolted to the inner ends of the wing spars and serve as a means of connecting the lower wings to the fuselage and the upper wings to the center wing panel. Interplane struts are vertical or inclined wooden struts of streamline section used to transfer compression stresses from the lower wings to the upper wings when the ma- chine is in flight. These struts are used in conjunction with diagonal stay wires which serve to transfer the load towards the center of the machine when in flight. The stay wires are divided into two general groups, those which take the drift load or fore-and-aft stresses due to the forward motion of the aeroplane, and those which take the lift load or vertical load due to the weight of the machine itself and the vertical resistance when in the air. The lift wires are again divided into those which take the load when the machine is flying and those which take it when on the ground. The wires which take the lift load when the machine is in the air are called the flying wires, and those which take the load when on the ground are called ground or landing wires. Drift and Anti-Drift Wires The set of wires in the wings which carry the drift load when flying are called the flying drift wires, or drift wires for short. There is no reversal of load in these wires when the machine is on the ground, but opposition wires are necessary to maintain structural symmetry. These latter are called the anti-drift wires. When the wings are covered it is of course impossible to inspect the internal stay wires of the wings, hence every precaution must be taken to guard against corro- sion. The wire used at this point is tin coated before assembling, the steel parts of the turnbuckles and other fittings are copper plated and when completely assembled, all the metal parts are given a coat of enamel paint. All screws, tacks and brads are of brass or copper. Wings are covered with a closely woven fabric. At present unbleached linen seems to give the best satisfac- tion. Owing to its scarcity, however, a satisfactorv sub- stitute is being sought for. A cloth made of long fibre sea island cotton is used to some extent and makes a fairly satisfactory substitute. Linen fabric weighs 3 1 /-; to -1% oz. per sq. yd. and has a strength of 60 to 100 Ibs. per in. of width. Its strength is increased 25 to 30 per cent, by doping, however. The weight of cotton fabric is 2 to 1 oz. per sq. yd., its strength 30 to 60 Ibs. per in. of width, and its strength is increased 20 to 25 per cent, by the application of dope. The cloth surfaces or wing coverings must be taut, otherwise on passing through the air they would vibrate or whip. This would not only increase the resistance to a great extent, but soon would lead to the destruction of the fabric. A preparation called dope is used to tighten up the fabric and give a smooth, taut surface. It also tends to make the cloth weather-proof. Dope should be easy of application, durable, fire re- sisting and have a preserving effect on the cloth. Dopes at present are divided into two classes or chemical groups, those which are made from a base of cellulose nitrate or pyroxylin and those made from a cellulose acetate base. The base is dissolved in a suitable solvent, such as acetone for instance, and sometimes other substances are added to preserve flexibility or prevent drying out and cracking and checking or to modify shrinkage. The greatest difference between these two dopes is in their relative inflammability. The acetate dope makes the fabric not fireproof, but slow burning. A cloth treated with this dope will shrivel and char before burn- ing, but one treated with nitrate dope will burst into flame immediately on the application of a lighted match or when exposed to a strong spark or puncturrd by a flaming bullet, etc. Inspection windows are often inserted in wing sections over and under certain control joints where the latter are carried inside the .wing section itself. For instance, the aileron control cables are frequently run inside the lower wing sections to a pulley attached to the front or main spar opposite the middle of the aileron, the cable then passing down at a slight angle and through a thimble or sleeve in the lower covering of the wing section to the point where the cable is attached to the aileron control marst. With this construction inspection windows would be set in the upper and lower coverings of the lower wing immediately above and below the pulley over which the control cable passes. The inspection windows are usually of celluloid or other transparent material firmly sewn into the wing covering material. Stay Wires and Splices Stay wires and cables are used extensively in aeroplane construction. Much of the safety of the machine and pilot depends upon the quality of the material in the stay wires, the care used in adjusting them and on the char- acter of the terminal splices. Three kinds of materials are used for stay wires : solid or aircraft wire, stranded wire or aircraft strand, and a number of strands twisted together to form a cable and known as aircraft cord. Aircraft wire is a hard drawn carbon steel wire coated with tin to protect it against cor- rosion. Its strength runs from 200,000 to 300,000 Ibs. per sq. in., depending upon how small it is drawn. Draw- RIGGING .(in <=a j ^fcc >tc|.s in making an en.l splice in s,,|j ( | i rr ing increase! iolh the strength and hardness of this type of wire, but if drawn until too hard it cannot be bc,,t with safety. The aim is to pr.iducc .-, wire ,,f maxim,,,,, stren-tl,. ,,, ,(!, sufficient toughness to allow it to h.nd without fracture. A standard test for Unding is to grip the wir, ,,, ., \ ice whose jaws ha\e been round, d off 16 in. radius. ,nd bend the wire back and forth fcroagfa an angle of ivd, - Had, bend of MI d,-g. counts as one Lend. The minimum number of bends f l)r various si/, s of aircraft wires should be as follows: ir. of II. ;v s (Mllir e \- . 6 _ 5 ,.,, with , iu , fra ,., |lr ,. PM wir. ... II. A; S. gaugr No. 8- brmls without fracture. B * B Wo. lo || | H . n ,|s without fracture. r wire of II. \ S u.,,,^. \,, i., ,; |M . |1(U tt j,, H , u , f rn( . tlln . wire of l\. & S. gaugr No. It _:, Len.K without fractiirr For wire ,,f . & S. gauge No. Hi :i | M -i,,| s without fnictiire. Air, raft strand is composed of n number of small wires, usually Hi. twisted together. The individual wir- tlie strand are galvanized or zinc coated before being twisted into the strand. The complete strand is more flexible than a solid wire of the same diameter and is therefore mor, suitable for stay wires that are subject to \ ibration. The stay wins of the fuselage at the engine and wing panels .re of aircraft strand or cord, but for the remain- ing stay wiros of the fuselage aircraft wire is ordinarily Is, .| Aircraft cord is much more flexible than Hie strand. d tor control cables where these must pass over aratively small pulleys. The usual constrm-tion of iff cord is 7 strands of ]f tl'e stn.^th of th. nir,- ..self. \\ |,, n this t,,,,- ,,f ,,. rill f'ls ! is usually l,y sl.pping. If the fre,- end ,,l tl,. ""I -l-wn. ,,f,, r | M . illK , H . n , ,,, I( . k (|V| . r , |l( . fi . rnilr Hi an additional wrapping of wire. Ih, elli.-.encv of the ernun.d as whole will I,, m.r.as,,) to HO per 'cent of t > strength of the wire. If ,| lr w | 1() |,. ,,. rmillll | js SI1 , end the efldency Mill U- mere. ,,,,) I,, IM.I p, T ,.,.,,, rill "K I" >ttic tests. This is misleading, how i" such tests take no account of live load sir, or nl.ra tlnll Another form of terminal is- made by substituting a thin metal ferrule or section of flattened tulx- for the wrapped "in ferrule. It can be made secure either by soldering twisting after U-ing put in place. This terminal for I've or vibrational loads is ,u|>crior to the wrapped win- terminal as then is not so much difference j n mass l the wire and the ferrule. Aircraft Strand Terminals The terminal eye of the aircraft strand is formed around a thimble. The free end of the strand is brought around the thimble and either wr;ip|d to the main strand with small wires and soldi-red, or the free end is spliced into the main strand. Hefore bending around the thimble, the strand is wrapped with fine wire in order to prevent flattening or caging of the rfrand. The terminal eye of the aircraft cord is always made bv splicing the free end of the cord into the main strands after wrapping the cord around a thimble. Sometimes the splice is soldi-red but more often it is wrapped with harness twine. Foreign engineers are opposed to solder ing. claiming that the disadi. -ullages in the wav of cor rosion and overheating of the wire outweigh the advan- tages of the stronger terminals. The theory of the splice is simple. A strand or wire of the free end is wrapped around a strand or wire of the main cord, care being taken to have the iay of the wires the same. Three to five complete turns are given, three for the first and four to five for the last weaves of the splice in order to taper the splice gradually. Objections to tnliirrinfl. The most serious objections to soldering are: a. overheating; b. corrosive action of fluxes It is very easy to overheat and soften the wire and this is all the more serious because the softening tak place at a point where the wire is enlarged by the joint. The str.ss is naturally localised at this point. Some of the so-called non-corrosiir fluxes will upon application In- found to IM- more or less corrosi\c. F.\.n with strictly non corroxi\ e fluxes, tiiere is a carbonaceous residue, due to heat. dri\,n into the interstices between tin- wires of strands or cordV This serves as a holder for moisture and will in time cause corrosion. The corrosive effects of acid fluxes can be neutralized by the application of an alkaline solution, such as soda water. Washing the soldered splice of a solid wire witli 302 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING such a solution is very effective, but with strands and cords, where the acid is driven into the interior through the application of heat, it is questionable whether any system of washing will eliminate or neutralize the acid. Corrosion of the interior wires of a strand or cord may be concealed by a perfectly good exterior, giving an en- tirely false appearance of security. Turnbuckles Turnbuckles are made of three parts, the ferrule or sleeve, and the two ends. To distinguish the ends, they are called the yoke and eye ends, or the male and fe- male. Great care should be exercised when tightening or loos- ening turnbuckles that the cables are not untwisted or frayed. If the cables are untwisted a caging of the strands results which greatly weakens the cable. Cable that has been caged should be replaced. No pliers should be used when tightening or loosening turnbuckles. The correct method is to use two drift pins or nails, one through the terminal eye of the cable to prevent the end of the cable twisting, the other through the hole in the barrel of the turnbuckle. Pliers will scar the wires, which is objectionable for three reasons, the first two of which mav lead to serious consequences. These reasons are: First, breaking the protective coating given to guard against corrosion. Second, a nick or scar in a wire or cable which would weaken it considerably. The wire or cable may not show much reduction of strength under a static load or test, but with a live or vibrational load the strength is greatly reduced and a slight nick will deter- mine the point of fracture. Third, disfiguration of the parts is offensive to the eye and bespeaks slouchy or care- less workmanship. Locking Devices A fair proportion of accidents occurs to moving mech- anism through nuts or other threaded fastenings working loose. It is safe to say that several hundred patents have been taken out for nut-locking devices, but of this great number, a few only are of practical value and used to any extent. The castellated nut and cotter pin used of course with a drilled bolt or stud is one of the few devices that finds large application. It is generally used in automobile and aeroplane work. The spring locking washer is another good device. This is used where the fastening is of a permanent or semi-permanent character. Another method is to batter or hammer down the end of a bolt a little. This should be practiced only as a last resort or as an absolutely permanent job and must be carefully done, otherwise serious damage will result to the bolt and nut. It is sufficient to close one thread on the bolt for part of the circumference only. Turnbuckles are secured against turning or loosening by running a wire through the adjusting hole in the turn- buckle sleeve and carrying the wire back and binding i around the ends of the turnbuckle. The proper way to lock a turnbuckle C H.M'TKK XII ALIGNMENT Hv tin ti-nn aeroplane alignment is meant the art of truing "|> an aeroplane, and ailj listing tin- parts in tli.-jr proper relation to each other as designated in the ... r,. plane's spccilicatioiis. Tin- inln-rrnt stability, tin- sp, , ,1. th<- rate of climb, tin- ctfieiency. in short the airworthin. -ss of an aircraft depend in large measure on its correct align- nifiit. 1 ,, r this reason the importance of careful and rorro-t alignment cannot be overestimated. 'I'ln instructions as gixcn in this chapter are not in- tend..! to be a complete and exhaustive treatise on the who], subject of aeroplane alignment, but are designed rather to give the beginner a good general idea of how the work is done. Thus with these instructions as ground work he can become proficient in the work after baring hail good practical experience in the hangars. The work of aligning an aeroplane divides naturally into several distinct and separate groups or divisions a. fuselage, b. horizontal and vertical stabilisers, c. landing d. center w ing section, e. wings, f. controls. .Iliiinmenl of futrlage. The fuselage is aligned be- fore leaving the aeroplane factory and normally this align- ment will last for some time. The fuselage alignment should be checked over carefully, however, after an aero- plane has been shipped in disassembled condition. Strains on the fuselage caused by rough handling, bad landings, etc.. will make it necessary to re-align it. H' tore attempting to align any part of an aeroplane the erection drawings should be referred to if available, and the directions furnished by the makers should be followed carefully unless the operator has had a great deal of previous experience upon the particular type of aeroplane to be aligned, and is familiar with better meth- ods of procedure than those recommended by the maker. In general the procedure in aligning a fuselage will be about as follows: A horizontal reference plane is usually specified by the makers in connection with the fuselage. Sometimes the top longerons are taken as this reference plane, in which case they are to be aligned horizontally, laterally, and longitudinally from a specified station to the tail post. Sometimes horizontal lines are drawn on the vertical fuselage struts, and the fuselage is so aligned that these lines all fall in the same horizontal plane. Alignment of Longeron* In the first case, after the fuselage has been placed in a flying position, the top longerons are aligned for straight- using n straight edge and a spirit level to aid in finally placing them laterally and longitudinally in a horizontal plane. 303 The longerons are next aligned symmetrically with re- spect tc, the imaginary vertical plane of symmetry through the fore-and-aft axis of the fuselage. There' are two general methods of doing this, as follows : I irst Method The center points are marked on all horizontal fuselage struts. A small, stout cord is stretched from the center of the fuselage none to the tail post and the horizontal bracing wires adjusted until the centers of the horizontal struts fall beneath this line. A small surveyor's plumb bob is held at different |minU so that the suspending cord just touches the fore-and-aft align- ing cord. The centers of the bottom horizontal struts should fall directly below the bob. Second Method A plumb line is dropped from the center of the propeller and from the tail |x>st and a string is stretched on the ground or floor between these two points. Plumb bobs drop|ied from the centers of the horizontal struts must point to this line. The whole fuselage alignment is checked to make sure that it agrees with the specifications. If the aeroplane has a non-lifting tail, it would be advisable as the next step to support the fuselage in such a way that the rear part (about two-thirds of the total fuselage length) re- mains unsupported, and then re-check the fuselage align- ment once more. All turnhuekles should then be securely locked and the fuselage carefully inspected. Horizontal and Vertical Stabilizers The vertical stabilizer is examined to see that the bolts holding it in place are properly drilled and cotter-pinned, also to see that it is set parallel or dead on to the direc- tion of motion. It is trued up vertically by the turn- buckles on the tie wires or brace wires connected to it. These turnbuckles arc then properly safetied. The horizontal stabilizer usually is braced with tie wires fitted with turnbuckles. By means of these its trail- ing edge should be made straight and at right angles to the horizontal center line of the fuselage. All bolts fastening the horizontal stabilizer to the fuselage should be inspected to make sure they are properly drilled and cotter-pinned. All turnbuckles should be safetied, as pre- viously shown. .Ilifinmrnt of landing gear or undrr-carriagr. In as- sembling an aeroplane which has been completely dis- mantled, the landing gear should be assembled to thr fuselage and aligned with it before the wings are at- tached. In assembling and aligning the landing gear, the fuselage should be so supported that the landing gear 304 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING hangs free and the wheels do not touch the ground. The fuselage is placed in the flying position, or at least in such a position that the lateral axis is horizontal. There are three general methods of aligning the landing gear, as follows: First Method A small plumb is dropped from a poi on the fore-and-aft center line of the fuselage above the axle of the landing gear. A tack is placed in the exact center of the axle casing or a scratch is made on the axle at its center. The transverse tie wires are then adjusted until the tack or center line mark falls exactly below the plumb bob. The wires are made moderately tight. The exact degree of tautness required cannot very well be described; it is a matter of experience or personal instruc- tion. All turnbuckles are safetied and the landing gear inspected carefully. The strut fittings and the elastic shock absorbers should be inspected very carefully. Second Method The two forward transverse tie wires are adjusted until equal in length, then the rear trans- verse tie wires are similarly adjusted until they also are equal in length. All transverse tie wires are tightened equally and the turnbuckles safetied. The landing gear is then given a final inspection. Third Method The transverse tie wires are adjusted until the axle is horizontal as shown by a spirit level. This adjustment is made with the fuselage in the flying position or with the lateral axis horizontal. The trans- verse tie wires are tightened equally to the correct taut- ness, the turnbuckles safetied, and the landing gear in- spected as before. Center Wing Section Alignment of center wing section. The fuselage is first placed in the flying position, and the center wing section adjusted symmetrically about the fore-and-aft center line of the fuselage in plan. A tack driven in the middle of the leading edge of the center panel will then be directly above the center line of the fuselage. This is tested with a small plumb bob and checked by measuring each pair of transverse tie wires to see if the two wires of each pair are equal in length. The alignment for stagger is made by adjusting the stagger or drift wires in the fore-and-aft direction until the leading edge of the center panel projects the required distance ahead of the leading edge of the lower plane as given in the aeroplane specifications. This alignment is checked by dropping a plumb bob from the leading edge of the center panel and measuring forward in a hori- zontal plane from the leading edge of the lower plane to the plumb line. The adjustment for stagger fixes the rigger's angle of incidence. All turnbuckles are safetied and the alignment re-checked. Alignment of wing*. Before any attempt is made to align the wings the fuselage should be carefully inspected to make sure that it is properly riggeed and in proper alignment. Failure to do this may cause much delay and waste of time in aligning the wings. The next step is to make a general inspection of the wings, noting if all bolts and clevis pins are properly cotter-pinned. Note particularly the clevis pins where the interplane brace wires are fastened to the upper plane fittings. One of the largest aeroplane makers in tliis country puts these clevis pins in head down. In this position if the pins are not properly cottered, there is great danger of their working loose and dropping out, disconnecting the wires. Such matters are more easily remedied before the wings are aligned than afterwards. Loosen all wires between the planes including flying wires, ground wires, stagger wires and external drift wires. Examine the turnbuckles to see that the same number of threads show at both ends. If not, take the turn-buckle apart and remedy this. It will mean a sav- ing of time in the end if these matters are looked after before the actual truing up of the wings is begun. Flying Position Place the fuselage in the flying position as denned in the aeroplane's erection drawings. This may mean align- ing the top longerons or the engine bed or other specified parts laterally and longitudinally horizontal. This must be done carefully, using a good spirit level, because the wings are aligned from the fuselage upon the assumption that this flying position is correct. If it is necessary to get into the cockpit or in any other way disturb the fuselage during the alignment of the wings, make sure that the fuselage is still in the correct flying position be- fore proceeding further. Lateral dihedral angle. There are three common meth- ods of adjusting for lateral dihedral: Aligning Board First Method Aligning Board. 1 If an aligning board is available its use saves considerable time due to the fact that the rigger secures the lateral dihedral angle, straight- ness of wing spars, and correct angle of incidence near the wing tips all at the same time. The protractor level should read directly in degrees. Set this instrument at the number of degrees dihedral stated in the aeroplane's specifications. Place the aligning board parallel to the front spar (by measuring back from the strut fittings) and, keeping the flying and stagger wires loose, pull up on the ground wires until the bubble on the protractor level reads almost level. Since the aligning board is a straight edge it is easy to keep the front spar perfectly straight by glancing- beneath the aligning board occasion- ally. It should rest on at least three ribs, one near each end and one near the middle. The space between the other ribs and the aligning board should be slight. ^Dihedral Board FIG. 34 Method of using short dihedral board Place the aligning board in front of and parallel to the rear spar. Adjust the ground wires until the rear spai is straight and the dihedral is slightly greater than called for in the maker's specifications. Check at the front spar. It will now be the same as the rear. If not make it so. i See note on aligning boards at end of this chapter. ALK.XMKN I In. r, Points of iiieiisiin-ment for wing alignment Now tighten ilow n on all flying wires except those to the overhang, if then- is overhang. Test each pair of Hy- ing wires for equal taiitn, ss by striking with the edge of the hand and watching their vibration. The loose win- has Ih, greatest amplitude of vibration. The lateral di- hedral should now be exactly as called for in the spcciti cations. After aligning both wings for dihedral as stated above, both wings will lie the same height if the fuselage is h\el laterally. Check the height of the wings by making the distance BA (see Fig. 35) equal to DC measured from the longerons opposite the butt ends of the front spars on the lower wing panels. V is a tack in the middle of the leading edge of the center section panel. With a steel tape measure the distance V'A and VC. These dis- tant is should be equal. Kijiially good results may be obtained by using a pro- tractor spirit level in conjunction with an accurate straight edge. Second Method If a good aligning board is not avail- able the string method may be used. Fig. 36 shows the arrangement of the string which should be .small, smooth and tightly drawn. K-.-p the stagger wires, flying wires and nose drift wires loose as in the first method. Increase the dihedral angle, by tightening the ground wires, keeping the panels straight by sighting. The greater the dihedral angle the 'r the distance Y (see Fig. 36). The table below shows the variation for customary range of lateral di- hedral: TABLE FOR I. \TIKAI. DIHF.nRAI. ANGLES X Deg Inches Mist a nee from |Miint of support of string to eiel of spar Inches Distance from ml of spar vertically up to th- liori/ont il strinir 100 1 100 !% 2 3 4 100 100 100 3% 5% 7 5 100 8l Vi 6 100 Ktyta 7 100 U% 8 100 '"% 9 100 1J% 10 100 17*, Fio. 30 Alternative nirUMKi of aligning for dihedral 'I'lir distance X will probably not be exactly loo in. M given in tin- table, hut sin,-,- X and \ i, u . r , ..,. " jn ,|,,. ,,. proportion tlii.s i-, vrry simple. For example, tin- ili> tance X (convenient to m, asure) on a hipl.ine |,a\ i,,g a ieg. lateral dihedral angle may be, say { ft. i> in., or l.'iO in., which is one and one-half times 10(1 in. The table gives Y e|unl to S'/i in. for .S dcg. Our X i* one and one-half times the X in the table. Then our V must be one and one-half times :, i , in ( the Y given in the table), which equals ~~ ^ >.. which is the proper dis- tance up to the string when the wing has tin- cornet lat- eral dihedral. In determining the distance Y, always measure the vertical distance up to the string from near the inner edge of the wing panel, not from the center section panel. The correct lateral dihedral angle having been obtained, pro- ceed further as in the first method. Third Method On aeroplanes having sweep-buck the string method is rather difficult to apply. If an aligning board such as used in the first method is not available, then a .short dihedral hoard may In- made which will scric. Fig. 37 shows the construction and Fig. 31 the method of I ' Fin. :17 Short ililieilr.il Uwrd using such a board. It is plain that a separate board must be made for each aeroplane having a different di- hedral from the others at a flying field. Another disad- vantage of this board is the fact that it must IN- used IN- tween struts on the spars and is so short that it is apt to be affected greatly by unei|iial rib heights and any lack of straight nets in the spars. After obtaining the correct dihedral proceed as in tin- first method. Stiii/i/i-r is usually given in aeroplane specifications as a linear measurement in inches. The specifications will 300 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING of C orH (w/iictnver method of measuring ffi* specifications Co// forlis the sfoyoer. FIG. 38 Methods of measuring stagger tell whether it is to be measured on a projection of the chord or as a horizontal distance. (See Fig. 38.) It is important to measure the stagger in the manner directed. The stagger of the wings is fixed at the fuselage by the stagger of the center wing section. Align for stagger by adjusting the stagger wires between interplane struts. Slight adjustments only should be necessary. Fig. 38 shows the method. In exceptional cases the flying and ground wires, front and rear, nearest the fuselage, are used in adjusting the stagger, which is usually found to be correct, however, after slight adjustments of the stagger wires. Stagger is sometimes given as an angle of stagger in degrees. This can be converted into inches by the use of the lateral dihedral table on page 305. In this case AB in Fig. 38 corresponds to X in the table, and Y in Fig. 38 will be proportional to Y in the table. For instance if AB in Fig. 38 is 50 in. in a given aeroplane, or one- half of X in the table, and the stagger is given in the aeroplane's specifications as 7 deg., then the amount of stagger Y (Fig. 38) would be one-half of the 12 3/16 in. given in Column Y in the table opposite 7 deg. Overhang. If the aeroplane has much overhang it is usually supported by mast wires above and flying wires below. See that the flying wires are loose. Tightening one set of wires against an opposing set throws undue stress in members. Tighten up on the mast wires until the overhang inclines very slightly upward. Now tighten up on the flying wires below until the spars are straight. The leading and trailing edges of all wing panels should now be straight. In case there should be small local bows Spirit Level Sfraight Ee/ye Fio. 39 Measuring angle of incidence with straight-edge and spirit level Straight Jye FIG. 43 Another method of measuring angle of incidence. It can also be done advantageously by using a straight edge in conjunction with a protractor spirit level in the spars, with a little careful adjusting of wires these can usually be distributed equally between the upper and lower wing panels so that their effect will be lessened. Fixing the lateral dihedral or the angle of incidence for either upper or lower plane automatically adjusts it for the other plane. Rigger's angle of incidence. Check the lateral dihedral to make sure that it has not been altered in making other adjustments. If it is correct, front and rear, and the spars are straight, then the angle of incidence should be correct all along the wing. Figs. 39 and 40 show two methods of testing this. If the set measurements A or B are known, the first method (Fig. 39) can be used. If the angle AOB is given in the specifications then the sec- ond method (Fig. 40) can be employed. Test the angle of incidence near the fuselage and beneath the interplane struts. Wash-out and wash-in. Due to the reaction from the torque of the propeller the aeroplane tends to rotate about its longitudinal axis. To counteract this the wing which tends to go down (sometimes referred to as the " heavy " wing) is drawn down slightly at its trailing edge towards its outer end, or in other words it is given a slight addi- tional droop at this point. This is usually referred to as a " wash-in." The wing on the other side of the machine is given a slight upward twist, or " wash-out at a cor- responding point. In single-engined, right-hand tractors wash-in is given to the left wing and wash-out to the right. To increase the angle of incidence the rear spar must be warped down by slackening all the wires connected to the bottom of the strut and tightening all which are connected to the top of the struts, until the desired amount of wash-in is secured. This process is reversed to secure wash-out. For purposes of increased stability wash-out is some- times given both wings although of course some lift is lost by doing this. If it is still desired to compensate for the reaction due to the propeller torque, more wash-out is given on one side than on the other. The side having the least wash-out then has wash-in relative to the other side. Over-all measurements. Tighten the external drift wires only moderately tight. The following over-all measurements should now be taken, using a steel tape (see Fig. 35): Make BA=DC and LH = MN. Then OA should equal OC and HE should equal EN. These meas- urements should be made at points on the upper wing panels as well as the lower, making eight check measure- ments in all. All turnbuckles are now safetied (Fig. 41). Make a general final inspection of the wings to make sure that ALKi.N.MI.N T .{07 Block. *+ -' linliiiiln.il method ,if connc, tin^r aileron controls hat hern overlimkrtl. It mutt lie rrmrmbrrrd that in m,ikni, straightened as the ailerons are aligned on the aeroplane. Then- is difference of opinion about drooping the trail- ing edge of ailerons In-low the trailing edge of the plane to which they are fastened. At some fields the turn- buckles on the aileron control cables arc so adjusted that the trailing edge of the aileron lines up with the trail- ing edge of the wing panel to which it is hinged. At other fields, from ' s in. to :! , in. of droop is given the trailing edge of the aileron. Ix-cause it forms a part of a lifting surface and it is reasoned that. slack will IK- taken out of the lower control cables when the machine gets into the air. I'nless directed otherwise it perhaps is ad- visable to give little or no droop. The ailerons should work freely and respond quickly with no feeling of drag when the hand wheel is turned ToeA I /Vvfrvabr Sfrt/ffht Ed,. Teat for Srrotffttnttt r Tr>-ing an aligning board for itraightnriw >r the stick moved even very slightly. Improper coiling of rabies when a machine is dismantled will ruin tins ilitic.n .itMiut as quickly as anything ,-,,ii| ( |. c. ir< - must ! liken not to put too muc-li tension on the cables. The pulleys around which they run on- light, and not alw so strong as they might be. Cracked pulleys may so: times Ix- found on old macliin. s. Intcrplanc ailerons are adjusted so that both arc in the same plane when rontrol j s neutral. Tin- angle at whieh they are set must be given by the makers or d. t. rinin. -d by experiment and experience. Ktevatort. Fasten the bridge or stick control in its central position. Adjust the turnburkles on the control cables until the elevators are in tin ir ncutr.-il position and both are in tin- snme plane. Tighten the control cables enough to remove lost motion. liudden. Fasten the rudder footbar in its mid-posi- tion and adjust the turnbuckles until the rudder is in the neutral position, and the cables are tight enough to re- move lost motion. Both elevators :md rudders usually carry brace wires with turnbuckles which can be used in straightening their trailing edges. Notes on Aligning Boards To be useful an aligning I o.ird first of all must be true. Fig. 11 shows a method of testing such a board for straightness. (See A and B, Fig. 44.) Also by sup- porting the board as shown and setting the protractor lei i I at different degrees the protractor can be tried out. Ref- erence to the table for lateral dihedral on page :<<>;> shows the difference in thickness of the blocks for the different angles. The zero point may be tested by setting the in- strument at y.cro and supporting the aligning hoard on some surface known to !>r level. Tin inclin.ition for the board used- in the third method of aligning for lateral dihedral can be determined from the lateral dihedral table. Fifty inches make a convenient length for such a board, in which ease the Y (see Fig. 45) is just half of that given in the table for lateral dihedral I : Slum-ing series method of connecting ailerons in pair* Test of Proh+c/br U~/ Fio. 43 Alipninfr board us.-,! with Uble for lateral dihedral angles CHAPTER XIII CARE AND INSPECTION Cleanliness Control cables and wires Locking devices Struts and sockets Special inspection Lubrication Adjustments Vetting or sighting by eye Mishandling on the ground Airplane shed or hangar Estimating time Weekly inspection card form. Cleanliness. One of the most important items is clean- liness of all parts of the plane. After every flight the machine should be thoroughly cleaned. To remove grease and oil from the wings and covered surfaces, use either gasoline, acetone or castile soap and water. If castile soap cannot be obtained, be sure the soap used contains no alkali or it will injure the dope. In using the gaso- line or acetone, do not use too much or it will also take off the dope. A good way to use the latter is to soak a piece of waste or rag and rub over the grease or oil, theB wipe off with a piece of dry waste. When using soap and water be careful not to get any inside the wing as it is liable to warp the ribs or rust the wires. When mud is to be removed from the surfaces it should never be taken off while dry, but should be moistened with water and then removed. Other parts of the machine should be kept thoroughly clean to keep down the friction. Control cables and wires. All cables and wires should be inspected by the rigger to see that they are at the cor- rect tension. Also see that there are no kinks or broken strands in any of the cables or strands. Do not forget the aileron balance cable on top of the wings. When a wire is found to be slack do not tighten it at once but examine the opposing wire to see if it is too tight. If so the machine is probably not resting naturally. If the opposing wire is not over-tight then tighten the slack wire. All cables and strands and external wires should be cleaned and re-oiled about every two weeks. The oil should be very thin so that it will penetrate between the strands. Locking devices. All threaded fastenings and pins should be inspected very frequently to see that there is no danger of anything coming loose. Struts and sockets. Since the struts are compression members, largely, they should be examined on the ends for crushing and in the middle for bending and cracking. Special inspection. A detailed inspection of all parts of the machine should be made once every week. Usually there is an inspection sheet provided for this purpose. If no sheet is obtainable, then one should be made before the inspection is started. Make a list of all the parts to be inspected, starting at a certain point on the machine, and following around until that point is reached again. When each part or detail is inspected it should be checked on the sheet as defective or O. K. A good weekly inspection card form is given on the following page. Lubrication. Always see that all moving parts are working freely before a flight is made. This includes undercarriage wheels, pulleys, control levers, hinges, etc. 308 Adjustments. The angle of incidence, dihedral angle, stagger and position of the controlling surfaces should be checked as often as possible so that everything will be all right at all times. Alignment of the undercarriage should be made so that it will not be twisted and thus cut down the speed of the machine. I'etting or sighting by eye. This should be practiced at all times. When the machine is properly lined up, look at it and get a picture in your mind of just how it looks. Then when anything becomes out of line it can be easily detected without using any tools. See that the struts are in the same plane when looking at the front or side of the machine. The dihedral angle also can be checked by this method of sighting. Some flyers become so expert that they can check the alignment of the whole machine by eye. Distortion Always be on the lookout for dislocation of any of the parts. If any distortions cannot be corrected by adjust- ment of the wires, then the part should be replaced. Mishandling on the ground. Great care should always be taken not to overstress any part of the machine. Mem- bers are usually designed for a certain kind of stress and if any other kind is put upon them, some damage is likely to occur. When pulling an aeroplane along the ground, the rope should be fastened to the top of the undercar- riage struts. If this cannot be done, then fasten the rope to the interplane struts as low down as possible. Never lay covered parts down on the floor but stand them on their entering edges with some padding under- neath. Struts should be stood on end where they cannot fall down. Hangar. The hangar at all times should be kept in the best possible condition. Never have oily waste or rags lying around on the floor or benches, as these are liable to catch fire. No smoking should be allowed in or near the building. Do not have oily sawdust spread around on the floor to catch the oil but have pans for this purpose. In making replacements of defective parts, have a place for the old pieces. Never allow them to be put where they will be mistaken for new parts. Each tool should be kept in a certain designated place and when anybody borrows a tool, be sure that he puts it back where it belongs. Estimating time. When any repairs are to be made, learn to estimate the time required for the job. With a little practice this can be done very accurately. It may help sometime in making a report to an officer in charge as to when an aeroplane will be ready to go out again. AM) INSI'KCTIOX :,., Weekly Aeroplane Inspection Card --irult: I,,,/, /;,, It-. ''otters ./.>,./, .V,, !/..*. StraightneM h:n,,in, \,, M,,k, I/,,,/, | 'Kt I .ft I his eM urn--! ! in. ill,- mil li\ I iel.l Inspector for /;/< r. I-MTJ machine iiiuliT his charge, sign.-,! |, v him. ami must I,, ,l.,Mn^ tiin.nl oxer t,, II,,. Chirf Inspector as soon $ i,,.,,l, out. 1 1 inc. .-,ssci,il.|\ (lubricate with graphite grease) l.niK/in,/ ijrar: .. j|y . Wire Iriisi.in Wear Wire terminals Hinge pins :,u: /;,,,,. Holts, nuts, cotters, braces Valves K mldrr : Intake clearance Hinfre assembly I \lmiist olrarnnre Security Spark plufrs Wear Clean Hlnjfe pins and cotters ( iiip Control win- connections -l.uretor Mat S<-curity to manifold l-'oothar Bracing Kmyed control wire Manifold joints N'ote: Control wires frayed at any point of their length Oil tttm: IMllst |K> repl-l once. kage Pulleys ( )il (grade) Oil reservoir full Frpe r ">nlng Elrralort: Hinge assembly 6 ' Distributor lx>anl Wear Breaker point clearance HtafB pta rf 0*toW ...... I rans,,,,ss,on (drive) wear Contr((| wjn . ,.., ,,, tlr control: Control wire connections post 1'iillcys Frayed nintrol wire Wiring Note: Control wires frayed at any point of their length Bell cranks and connections must be replaced at once. ir tytttm : Pulleys Tank Creased Gasoline leads and connections Free running 1'iinip Right elevator Gasoline in tank full Left elevator j,>inli: Tail tkiil: ' I-ower wing right Skid Ix>wer wing left Fittings I'pprr wing right Shock absorber I'pper wing left Control*: icirrt: (tension, terminals clevis pins, cotters, safety Free and proper operation (lubricate with graphite wires) (frease) Flying wires right wing Elevator I h ing wires left wing K udder Landing wires right wing Aileron Landing wires left wing ./ li<;nmrn/ nf rittirr markinr : Wires, fittings, turnbuckles, cleaned and greased firtin,!*: (bolts, nuts, cotters) Right wing, upper lower I-eft wing, upper lower (Signed) Field Inspector. CHAPTER XIV MINOR REPAIRS Patching holes in wings Doping patches Terminal loops in solid wire Terminal splices in strand or cable Sol- dering and related processes Soft soldering Hard soldering Brazing Sweating procedure in soldering Fluxes Melting points of solders. The materials used in patching holes in linen-covered surfaces is unbleached Irish linen, the same kind as used in covering the wings. The material must be unbleached or it will not shrink the required amount. Generally the kind of dope used is Emaillite dope, although the acetate or nitrate dopes could be used. The dope should be ap- plied in a very dry atmosphere or on a sunshiny day at a temperature not less than 65 deg. F. A brush or a piece of waste may be used to apply the dope. In patching a hole the first thing to be done is to clean the surface of the old dope. To do this, fine sand paper may be used or acetone, gasoline or dope. In using the sand paper, care should be taken not to injure the cover- ing. When using the acetone or gasoline, it should be put on the surface, allowed to stand for a while to soak up the old dope, then scraped off. The same method is applied when using dope to clean the surface. After the surface is cleaned, the edges of the hole should be sewed if it is of any considerable size. To do this sewing linen thread and a curved needle are used. The stitches should not be closer together than !/> in. and far enougli back from the edge so that there is no dan- ger of their tearing out. With a small hole, such as a bullet hole for instance, it is not necessary to do any sewing. When the hole is several inches square, a piece of unbleached linen should be sewed in to give a body for the top patch so that it will not be hollow in the center after it is dry. The sewing up of holes should be done after the surface is cleaned so that any slackness may be taken up before the patch is applied. After sewing is finished the patch is cut. It should be made about 1 to 2 in. larger on each side than the hole. The edges of the patch must be frayed for about 1/4 in., this being done to prevent them from tearing easily. Dope should now be applied to the wing. Generally several coats are put on so that there will be a sufficient amount to make the patch stick well. After the last coat is applied the patch should be put in place immediately before the dope has a chance to dry. Any air bubbles and wrinkles should now be worked from under the patch by rubbing with the fingers, and more dope put on top of the patch. Usually there are six or seven coats of dope applied on top of the patch, allowing time for each coat to dry before another is applied. Any small amount of slackness in the patcli will prob- ably be taken out as the linen shrinks. If the patch is hollow after the dope is thoroughly dry, however, it is not a good patcli and should be removed. A good patch 310 should be tight around the edges as well as in the center over the hole and should contain no creases or air bubbles. Terminal Splices A loop or splice must be formed in the end of every brace wire or control cable where it is attached to a strut socket, turnbuckle, control mast, or other form of term- inal attachment. The manner of making the loop or splice in the wire will vary according to the type of wire or cable used. The terminal in the end of a solid wire is made in the manner shown in Fig. 33. There are several points to be observed in making tin's type of terminal splice, as follows: (a) The size of the loop should be as small as possible within reason, as a large loop tends to elongate, thus spoiling the adjustment of the wires. On the other hand, the loop should not be so small as to cause danger of the wire breaking, due to too sharp a bend, (b) The inner diameter of the loop should be about three times the diameter of the wire, and the reverse curve at the shoulders of the loop should be of the same radius as the loop itself. The shape of the loop should be symmetrical. If the shoulders are made to the proper radius there will be no danger of the fer- rule slipping up towards the loop, (c) When the loop is finished it should not be damaged anywhere. If made with pliers there will be a likelihood of scratching or scoring the wire, which would weaken it greatly. Any break or score in the surface coating of a wire destroys the protective covering at that particular point and the wire will soon be weakened by exposure. A deep nick or score would greatly weaken the wire and eventually result in breakage at that point. Splicing a strand or cable. The splice in the end of a strand or cable is entirely different from the terminal of a solid wire. The end of the strand is led around a thimble and the free end spliced into the body of the strand or cable just below the point of the thimble. Such a splice is afterward served with twine, but the serving should not be done until the splice has been inspected by whoever is in charge of the workshop. The serving might cover bad workmanship in the splice. Soldering. Terminal loops or splices in solid wire and also splices in the ends of strand or cord are sometimes soldered after being formed. There are some objections to soldering at these points, however, as outlined on page 301. The ensuing instructions for soldering work will prove valuable in case where this method of securing a terminal splice is considered desirable. I: MINOR R I.I'. MRS .-ill Jinninif uf m ft alt hi/ 3w . at inc. Tins is a process used where tin- \- to lie joined can tirst lie fitted together, then individually d with solder, then clamped together and heated until the solder Hows md cements them solidly together. This method allows for a more perfect joint being made. The more accurately the parts are fitted together the stronger the union will lie. Also, the thinner the coat of solder- ing material, within reasonable limits, the stronger the joint. All of the above methods are used more or less in aero- plane construction and maintenance, but the one that is most generally used is the first, or soft-soldering method. Cle-niliness is of prime importance in making joints or fastening by any of these methods. In soldering, the first step is to see that the soldering copper is clean and well tinned, for this may determine the success or fail- ure of the job. There are several ways of cleaning and tinning the soldering copper, but the one recommended b to heat the copjxr to about 600 deg. F., then dip the point (jiiiekly into a cup or jar containing ammonium chloride (Nil, (1) and granular tin or small pieces of r. If any considerable amount of work is to be done, an earthen jar or a teacup can be used, and kept partly tilh d with this mixture. Tinning Soldering Coppers Another way of tinning the soldering copper is to make prcssion in a piece of sheet tin and place in it a small lii.intity of soldering flux together with a piece of solder. the copper until bright, heat it to about 6OO deg. F., and then move it around, while hot, in the depression in the tin until it becomes coated with molten solder. It will now IM- ready to use. The n,\t step is to clean thoroughly the parts to be joint d. using fine emery cloth, sandpaper or a scraper. If the parts are of raw material, sandpaper will do, but if they are old parts which previously have been exposed. or if a In i\ y ovule has formed, the surfaces to be soldered should U iihd or script d until jicrfectlv bright and clean. The , ! rface should then IK- covered with soldering fluid or one of the iii.inv soldering pa- II' it the soldi ring copper to about tiOO deg. F., and touch it to (he solder, being careful to get only a small amount of solder on the copper. Hub the copper over the surfaces to lie joined until n bright, even coating of solder clings to the surfaces. Place the pieces together and .ntil the solder flows, using the hot copper to furnish the necessary heat and adding more solder as n. Care irtust be taken not to overheat the pieces at the joint. as this has a ten.!- m v to weaken the metal at that point and may cause trouble. The same general procedure as the above is followed for hard soldering, with the exception that a higher tem- perature must be applied. Fluxes 1 luxes arc used in soldering to prevent, so far as pos- sible, the formation of oxides on the heated surfaces, and to flux off those that may have formed. Acid fluxes are the most effective and on iron or steel are practically >ary. The objection to their use is that unless the parts are thoroughly cleaned after soldering the acid in the flux attacks and corrodes them. In the case of stranded wires or cables the flux will penetrate into the minute spaces between the strands and will IK- extremely difficult to remove or neutralize, even when the cable or wire is washed with or dipped in an alkaline solution, such as soap or soda water. Some of the fluxes in general use are: Xinc chloride (/n Cl), corrosive Dilute muriatic acid (H Cl), corrosive Resin, non-corrosive. This is satisfactory for tin, but will not work on galvanising. Hi-sin and sperm candle melted together make a fair non-corrosive paste. For either tin or galvanising use three parts resin to one part sperm candle. Sometimes licttcr results are obtained on dirty surfaces by adding one part alcohol to this mixture. Mfllinij point* of tcAdert. The melting points of sol- ders composed of tin and lead in various proportions are as follows: Proportion Mrllinp Point Tin Lead 1 part 1 part 1 part \\ parts 6 parts .'i parts 5 parts 1 part 1 part 1 nrt 44H rfrjr. F. All sition of 1 to I is most commonly used for tin- smithing. For electrical work where the solder i* used in the form of wire, a proportion of \\'. 2 to I or to 1 is used. CHAPTER XV VALUE OF PLYWOOD IN AEROPLANE FUSELAGE CONSTRUCTION BY LIEUTENANT STEFANS D'AMico, Italian Aviation Mission. Recently aeroplane construction has undergone some very radical changes, in part due to the exigencies caused by the war, in part to the natural tendency to make a more and more organic machine out of the aeroplane, by employing in its design the same fundamental principles which guide the design of modern mechanical devices. Often these two conditions have coincided so as to ex- pedite the ultimate result. Of all the parts of the aeroplane, the fuselage has un- doubtedly undergone the most radical change. On the one end the development of aerodynamics and the neces- sity to get from the aeroplane the greatest speed coupled with the greatest mobility have changed its form and pro- portions, and on the other hand modern and more practical principles of construction have completely altered its make-up. Until recently, the fuselage in all aeroplanes consisted of a frame suitable to withstand the stress and this was then covered with linen properly varnished. The frame consisted of four longerons, running length- wise of the fuselage with struts and steel wires latticing in both planes, vertical and horizontal, so as to divide it into panels. The joints of the struts to the longerons were metallic fittings and the proper tension in the latticing was obtained by the use of turnbuckles. The solid resulting by this method is capable of with- standing the stresses imposed from all sides but is a com- plicated structure, since it is made up of a large number of parts, has a great many wire connections, and must be frequently adjusted to the proper shape by giving the wires the proper tension. The fuselage, because of the frequent landing, is sub- jected to violent dynamic stresses causing a stretching in the tension wires, a disarrangement of the whole structure, as well as a stretching of the linen covering. The ele- ments also influence to a great extent the stretching of the covering and this impairs to a large degree the aero- dynamic property of the machine. The war then has developed it to such an extent, that while the fuselage has forfeited a little the advantage in weight, the machine has gained in life and efficiency. At any rate, the abandoning of such a construction was desirable because of the ever-increasing scarcity of metal fittings of alloy steel, as well as for the excessive cost and the lack of labor which is felt more each day. The use of plywood, which had already been used in large quantity in the construction of hydroaeroplane boats, appeared to be very appropriate since it eliminated a great many of the disadvantages enumerated. In as much as the only advantage of the old type was its lightness, all the builders tried very hard to make the best use possible of the material in order to eliminate this disadvantage which, in some cases, is considerable. In its most common form the modern fuselage is made of four longerons, tied together by means of diaphragms and then covered by plywood. The shearing stresses are taken care of by stiffening the outside covering with ribs of wood. The transverse stiffness is attained by means of trans- verse diaphragms in the rear, while in the front, where this is not possible, since the passengers have to be accom- modated as well as the tanks, motors, etc., this is done in a special way for each case, utilizing to the best ad- vantage the space resulting in distributing the various parts of the plane. The plywood is made to resist the moments due to deflection and principally shearing stresses. In this way the material is used to its full extent and its strength utilized to the best advantage. Therefore, since the material is used to its full value, the construction becomes light. The maximum strain on the fuselage comes on it when the tail skid strikes the ground. The maximum reaction will naturally depend on the total load P, which comes on it at this point and in computing, it is customary to con- sider this as double; that is 2P. (Fig. 1 and Fig. 2.) Therefore, at the section X distant from the point where the load may be considered as applied the moment. > MX = JP.X From this moment must be deducted the moment due to own weight of the fuselage so that the resulting expres- sion will be M'x=ZPx P'x. In its vertical direction the fuselage suffers a deflecting moment due to the compound load coming on the rudder. If this force be denoted by P" then Mx"~P" O -f c ) in which C is the distance from the axis of the tail and the center of pressure of the surface which makes up the rud- der. Considering the ordinary quadrangular form of fuse- lage, the distance Hx between the centers of gravity of the upper and lower longeron of the section H'jc of the longerons may be considered variable and following the linear law. So that: hx = ho &i ho oc x; oc = I Also in the horizontal section the distance A.r between the centers of gravity of the sections of the longerons may be considered in the same way as varying with straight line law. 312 PLYWOOD IN .\F.KoiM..\M. PUSELAGI CONSTR1 CTIOH :n.. Imill or inlrrior Cfou r.in~MTsc jririli-r >r<-ti 1| f I * < ^ T i ; \ ~ X. E J -,,...!,,,; "I ll'l M -Ml I P-"l' i |MW| "|'J|| UI.JJ ,., mi ui. 'i**i:t u,.^,., 4W , - iii"* >UI lUt. '.iwl ui nj j*d qi qi mnat|x*in 01 !|J,, n "Jl I" ill. 8 " S - >, in* i; 'no jad -q> !!!! 1 } ] | ! i ! i || < ! i i u sn n !-!!! !| ?=>. q - ? AI. 2 = * *. *< *! O. l - - r i - o gc - o> 33353333S 3 3 55 3 3 3 3 33 553 25 335335333 S S 35 as s 3 3| - 55 - * ' * *\ ~ ? ^ "i * fc a M * S. = -*. tc c ij I T3 e 5 ~ J*j * fllJI 11 s- ^^ J : \ : f : ^ - '? c jf := ^ c !?^- ^ (B ^^ ^ - | 2 C i >. i- ! l H i ? t = S S -=.= = r c - fe 2 - V ' 3 1 7 ^ - r s t f ^ lit 1 :? scnrjrn MM li.i 3 x - ~ 2 S !-_ -^ s J :| * z 2 s i = * t * rf ITS 5 s-t-l S B.S 55^-3 - b.2 S o^ii .^i2*j<_^ III CHAPTER XVI NOMENCLATURE FOR AERONAUTICS AERODYNAMICS The science which treats of the air or other gaseous bodies under the action of forces and of their mechanical effects. AEROFOIL A thin wing-like structure, flat or curved, de- signed to obtain reaction upon its surfaces from the air through which it moves. AERONAUTICS That branch of engineering which deals with the design, construction and operation of air craft. AILERON A movable auxiliary surface used for the coi trol of rolling motion of an aeroplane, i. e., rotation about its fore and aft axis. AIRCRAFT Any form of craft designed for the navi- gation of the air; aeroplanes, balloons, dirigibles, helicopters, kites, kite balloons, ornithopters, gliders, etc. AERODROME The name usually applied to a ground and buildings used for aviation. AEROPLANE A form of aircraft heavier than air, which has wing surfaces for sustentation, stabilizing sur- faces, rudders for steering, power plant for propul- sion through the air and some form of landing gear; either a gear suitable for rising from or alighting on the ground, or pontoons or floats suitable for alight- ing on or rising from water. In the latter case, the term " Seaplane " is commonly used. (See defini- tion.) p us her A type of aeroplane with the propeller or pro- pellers in the rear of the wings. Tractor A type of aeroplane with the propeller or propellers in front of the wings. Monoplane A form of aeroplane whose main sup- porting surface is disposed as a single wing extend- ing equally on each side of the body. Biplane A form of aeroplane in which the main sup- porting surface is divided into two parts, one above the other. Triplane A form of aeroplane whose main support- ing surface is divided into three parts, superimposed. Multiplane An aeroplane the main lifting surface of which consists of numerous surfaces or pairs of su- perimposed wings. One and One-Half Plane A biplane in which the span of the lower plane is decidedly shorter than that of the upper plane. Flyiny Boat An aeroplane fitted with a boat-like hull suitable for navigation and arising from or alighting on water. Seaplane An aeroplane fitted with pontoons or floats suitable for alighting on or rising from the water. AIR POCKET A local movement or condition of the air 316 causing an aeroplane to drop or lose its correct atti- tude. AIR SPEED METER An instrument designed to measun the velocity of an aircraft with reference to the air through which it is moving. ALTIMETER An instrument mounted on an aircraft to continuously indicate its height above the surface of the earth. ANEMOMETER An instrument for measuring the velocity of the wind or air currents with reference to the earth or some fixed body. ANGLE OF ATTACK The acute angle between the direc- tion of relative wind and the chord of an aerofoil, i. e., the angle between the chord of an aerofoil and its motion relative to the air. (This definition may be extended to any body having an axis.) Best Climbing The angle of attack at which an aero- plane ascends fastest. An angle about half way be- tween the maximum and optimum angle. Critical The angle of attack at which the lift is a maximum, or at which the lift curve has its first maximum; sometimes referred to as the "burble point." (If the lift curve has more than one maxi- mum, this refers to the first one.) Gliding The angle the flight path makes with the horizontal when flying in still air under the influence of gravity alone, i. e., without power from the en- gine. Maximum The greatest angle of attack at which, for a given power, surface and weight, horizontal flight can be maintained. Minimum The smallest angle of attack at which, for a given power, surface and weight, horizontal flight can be maintained. Optimum The angle of attack at which the lift-drift ratio is the highest. ANGLE OF INCIDENCE (Rigger's Angle) The angle be- tween the longitudinal axis of the aeroplane and the chord of an aerofoil. APPENDIX The hose at the bottom of a balloon used for inflation. In the case of a spherical balloon it also serves for equalization of pressure. ASPECT RATIO The ratio of span to chord of an aerofoil. AVIATOR The operator or pilot of heavier-than-air craft, This term is applied regardless of the sex of the operator. AVION The official French term for military aeroplane; only. AXES OF AN AIRCRAFT The three fixed lines of refer- ence; usually passing through the center of gravitj and mutually rectangular. The principal axis in : NO.MKM I.ATl ]{K 10R AKKONAI Tit s 817 forr .-Hid aft direction, iisuallx parallel tu (lit- axis of tin propeller and in tin- plane of s\ mmetri . is tin- Longitudinal Axis or the lor. and Alt Axis The axis perpendicular to this anil in tin plain of ,\m nietry is the Vertieal Axis; the third axis perpendicu- lar to the other two is the Lateral Axis, also called the Tr IIISM rse Axis or the Athwartship Axis. In miithe niatieal diseiission the first of these axes, drawn from Iron! to nar is called the \ Axis; tin- si rond, drawn upward, the / Axis; and the third, forming a " left- liandi-d " s\ stem, tin Y Axis B.U.\MMI < ovnioi. Si HFACE A type of surface se- etired liy adding area forward of the axis of rota- tion. In an airstrcam a force is excrtid on this .id ! d an a. tending to aid in the movement about the axis. H\i \NIIN.. I LAPS (See AILERON.) ISwinSKT A small balloon within the interior of a balloon or diri^ihle for the purpose of controlling the ascent or de.sci nt. and for maintaining pressure on the outer envelope so as to prevent deformation. The ballonet is kept inflated with air at the required pressure, under the control of a blower and valves. BALLOON A form of aircraft comprising a gas bag and a basket and supported in the air by the buoyancy of the gas contained in the gas bag, which is lighter than the amount of air it displaced; the form of the gas bag is maintained by the pressure of the contained gas. Barrage A small spherical captive balloon, raised as a protection against attacks by aeroplanes. ('attire A balloon restrained from free flight by means of a cable attaching it to the earth. Kite An elongated form of captive balloon, fitted with tail appendages to keep it headed into the wind, and deriving increased lift due to its axis being inclined to the wind. Pilot A small spherical balloon sent up to show the direction of the wind. Soundiny A small spherical balloon sent aloft, with- out passengers, but with registering meterological in- struments for recording atmospheric conditions at high altitudes. BALLOON DIRKIIBLE A form of balloon the outer en- velope of which is of elongated horizontal form, pro- vided with a car, propelling system, rudders and stabilizing surfaces. Dirigibles are divided into three classes: Rigid, Semi-rigid and Non-rigid. In the Rigid type the outer covering is held in place and form by a rigid internal frame work and the shape is maintained independently of the contained gas. The shape nnd form of the Semi-rigid type is maintained partly by an inner framework and partly by the contained gas. The Non-rigid type is held to form entirely by the pressure of the contained gas. HW.LOON BED A mooring place on the ground for a captive balloon. BALLOON CLOTH The cloth, usually cotton, of which balloon fabrics arc made. BALLOON FABRIC The finished material, usually rub- berized, of which balloon envelopes are made. BANK To incline an aeroplane laterally, i. e., to rotate it al'out the fore-and-aft axis when making a turn. Right li-ink is to incline the aeroplane with the right win^r down. Also usi d as a noun to di si-rilie tin- position ni an aeroplane when its lateral axis is in- clined to the horixontal. BAROGRAPH An instrument for recording xariatmns in barometric pressure. In aeronautics the charts on which the records are made are prepared to indicate altitudes directly instead of barometric pressure, in- asmuch as the atmospheric pressure varies almost directly with the altitude. BAROMETER An instrument for measuring the pressure of the atmosphere. BANKET The i-ar suspended beneath the balloon for passengers, ballast, etc. BIPLANE (See AEROPLANE.) BODY (or AN AEROPLANE) A structure, usually < n closed, which contains in a streamline housing the powcrplant, fuel, passengers, etc. Fuirlage A type of body of streamline shape carry- ing the empannage and usually forming the main structural unit of an aeroplane. Monocoque A special type of fuselage constructed of metal sheeting or laminated wood. A monocoque is generally of circular or elliptical cross-section. \acelle A type of body shorter than a fuselage. It does not carry the empannage. but acts more as streamline housing. Usually used on a pusher type of machine. Hull A boat -like structure which forms the body of a flying-boat. BONNET The appliance, having the form of a parasol, which protects the valve of a spherical balloon against rain. BOOM (See OUTRIGGER.) BOWDEN WIRE A stiff" control wire enclosed in a tube used for light control work where the strain is com- paratively light, as for instance throttle and spark controls, etc. BOWDEN WIRE GUIDE A elose wound, spring-like, flex- ible guide for Bowden wire controls. BRIDLE The system of attachment of cables to a balloon, including lines to the suspension band. BULLS EYES Small rings of wood, metal, etc., forming part of balloon rigging, used for connection or ad- justment of ropes. BURBLE POINT (See ANGLE CRITICAL.) CABANE (OR CABANC STRUT) In a monoplane, the strut or pyramidal frame work projecting above the body and wings and to which the stays, ground wires, braces, etc., for the wing arc attached. In a biplane, the compression member of an auxili- ary truss, serving to support the overhang of the upper wing. CAMBER The convexity or rise of the curve of an aero- foil from its chord, usually expressed as the ratio of the maximum departure of the curve from the chord as a fraction thereof. Top Camhrr refers to the top surface and Bottom Camber to the bottom surface of an aerofoil. Mean Cambrr is the mean of these two. CAPACITY-CARRYING The excess of the total lifting ca- pacity over the dead load of an aircraft. The latter 318 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING includes structure, power plant and essential acces- sories. Gasoline and oil are not considered essential accessories. The cubic contents of a balloon. CAPACITY-LIFTING (See LOAD) The maximum flying load of an aircraft. CATHEDRAL A negative dihedral. CEILING The maximum possible altitude to which a given aeroplane can climb. CENTER The point in which a set of effects is assumed to be accumulated, producing the same effect as if all were centered at this point. There are five main centers in an aeroplane Center of Lift, Center of Gravity, Center of Thrust, Center of Drag and Center of Keelplane Area. The latter is also called the Directional Center. The sta- bility, controllability and general air worthiness of aeroplane depend largely on the proper positioning of these centers. CENTER OF PRESSURE OF AN AEROFOIL The point in the plane of the chords of an aerofoil, prolonged if neces- sary, through which at any given attitude the line of action of the resultant air force passes. (This definition may be extended to any body.) CENTER PANEL The central part of the upper wing (of a biplane) above the fuselage. The upper wings are attached to this on either side. CHORD (Of an aerofoil section.) A straight line tan- gent to the under curve of the aerofoil section, front and rear. CHORD LENGTH (Or length of Chord.) The length of an aerofoil section projected on the chord, extended if necessary. CLINOMETER (See INCLINOMETER.) _ CLOCHE The bell-shaped construction which forms the lower part of the pilot's control lever in the Bleriot control and to which the control cables are attached. COCKPIT The space in an aircraft body occupied by pilots or passengers. CONCENTRATION RING The hoop to which are attached the ropes suspending the basket (of a balloon). CONTROLS A general term applied to the mechanism used to control the speed, direction of flight and alti- tude of an aircraft. Bridge (Deperdussin-" Dep " Control) An inverted " U " frame pivoted near its lower points, by which the motion of the elevators is controlled. The ailer- ons are controlled by a wheel mounted on the upper center of this bridge. Dual Two sets of inter-connected controls allowing the machine to be operated by one or two pilots. Shoulder A yoke fitting around the shoulders of the pilot by means of which the ailerons are operated (by the natural side movement of the pilot's body) to cause the proper amount of banking when making a turn or to correct excessive bank. (Used on early Curtiss planes.) Stick (Joy-stick) A vertical lever pivoted near its lower end and used to operate the elevators and ailerons. COWLS The metal covering enclosing the engine section of the fuselage. CHOW'S FOOT A system of diverging short ropes for dis- tributing the pull of a single rope. (Used princi- pally on balloon nets.) DECALAGE The difference in the angular setting of the chord of the upper wing of a biplane with reference to the chord of the lower wing. DIHEDRAL (In an aeroplane) The angle included at the intersection of the imaginary surfaces containing the chords of the right and left wings (continued to the planes of symmetry if necessary). This angle is measured in a plane perpendicular to that intersec- tion. The measure of the dihedral is taken as 90 deg. minus one-half of this angle as defined. The dihedral of the upper wing may and frequently does differ from that of the lower wing in a biplane. Lateral An aeroplane is said to have lateral dihedral when the wings slope downward from the tips to- ward the fuselage. Longitudinal The angular difference between the an- gle of incidence of the main planes and the angle of incidence of the horizontal stabilizer. DIRIGIBLE A form of balloon, the outer envelope of which is of elongated horizontal form, provided with a propelling system, car, rudders and stabilizing sur- faces. Non-Rigid A dirigible whose form is maintained by the pressure of the contained gas assisted by the car suspension system. Rigid A dirigible whose form is maintained by a rigid structure contained within the envelope. Semi-rigid A dirigible whose form is maintained by means of a rigid keel and by gas pressure.. DIVING RUDDER (See ELEVATOR.) DOPE A preparation, the base of which is cellulose acetate or cellulose nitrate, used for treating the cloth surfaces of aeroplane members or the fabric of balloon gas bags. It increases the strength of the fabric, produces tautness, and acts as a filler to make the fabric impervious to air and moisture. DRAG The component parallel to the relative wind of the total force on an aircraft due to the air through which it moves. That part of the drag due to the wings is called "Wing Resistance" (formerly called "Drift"); that due to the rest of the aeroplane is called " Para- site Resistance" (formerly called head resistance). The total resistance to motion through the air of an aircraft, that is, the sum of the drift and parasite resistance. Total Resistance. DRIFT The component of the resultant wind pressure on an aerofoil or wing surface parallel to the air stream attacking the surface. Also used as synonymous with lee-way. (See DRAG.) DRIFT INDICATOR An instrument for the measurement of the angular deviation of an aircraft from a set course, due to cross winds. Also called Drift Meter. DRIFT WIRES Wires which take the drift load and trans- fer it through various members to the body of the aeroplane. DRIP CLOTH A curtain around the equator of a balloon NOMI.M 1, ATI UK 1 (K A KK< >N A I TU s which prexents rain from dripping intu tin basket. DROOP (a) An aileron is said to h.-uc droop when ii ,. . justed tin! its trailing edge is In low tin- trilling edge of tin in nil plane. (6) When :i winy is warped In gixe wash out or wash ill, its trailing edge will. relatue to the le iding edge, be displaced progressively from on> . n.i to tin- otlu-r. A downward displaeeneBi is called droop. .IK.XXTOH A hinged surface, usually in tin- form of a hormuit.il niddi-r. inoiintcd nt the tail of an aircraft for controlling tin- longitudinal attitiulc of tin- air- craft, i. r.. it-, rotation about tin- lateral a\is. K \n-\\\ M.I A term applied to the tail group of parts in aeroplane. - Txn..) '.M.iNt SIM. BKARERS, STPPORTS The members form- mi: tin- engine lied. NHIIIM. F.IM.K The foremost part or forward edge of an arrofoil or propeller blade. ri The portion of the balloon or dirigible which contains the '.grxroR The largest horizontal circle of a spherical balloon 'xiuiNi. A wood or metal form attached to the rear of struts, braces or wires to give them a streamline shape. ;"'AIH LEAD A guide for a cable. FIN A small fixed aerofoil attached to part of an air- craft to promote stability; for example, tail fin, skid tin. ete. Fins may be either horizontal or vertical and are often adjustable. STXHII.IXER.) >'IKK D\MI A metal screen dividing the engine section of an aeroplane body from the cockpit section. jFi.n.iiT PATH The path of the center of gravity of an aircraft with reference to the earth. 'i.o\ r That portion of the landing gear of an aircraft which provides buoyancy when it is resting on the surface of the water. i> Lvi\(. HOAT (See AEROPLANE.) 'LXIM; POSITION The position of a machine, assumed when (lying horizontally in still air. When on the ground the machine is placed in a flying posi:ion by leveling both longitudinally and laterally. The two longerons, engine sills or other perpendicular parts designated by the maker are taken as reference points from which to level. OOT BAR (See RrnnER BAH.) i M;E (See BODY.) I.AI.K COVER A cover placed on a fuselage to pre- serve a streamline shape. JAP The shortest distance between the planes of the chords of the upper and lower wings of a biplane. >x- li xo (See ENVELOPE.) - To fly without power and under the influence of gravity alone. A form of aircraft similar to an aeroplane but without any power plant. When utilized in variable winds it makes use of the soaring principles of flight and is sometimes called a snaring machine. ANGLE (See ANGLE.) (MINK One ot tin- segments of fabric comprising t' I" of a balloon. ( linn \n l to MI ( nix as placed mi the | pro i balloon. l(ri A long trailing rope alt irlicd to spherical balloon or dirigible to serve as a brake and as a vari- able ballast. GfY A rope, chain, wire ,.r rod attached to an objr.t t - . . "r sti iily it, such as guys to wing, tail or landing gear. 1 1 xMiAB An aeroplane si HEAD KK-I.-TANCE (See PARASITE RKMSTANCB.) HELICOPTBR A form of aircraft whose support in the air i.s derived from the vertical thrust of prop- lit rs. HORN-CONTROL ARM An arm at right angles to a con- trol surface to which a control cable i, attach, d. for example, aileron horn, rudder horn, elevator horn, ete. Yore commonly called a Mail. Ill- 1. 1. t See Honv.) IN< : INOMKTEH An instrument for measuring the angle made by the axis of an aircraft with the horizontal. hiiliralor-Hankinff An inclinometer indicating lateral inclination or bank. INSPECTION WINDOW A small transparent window in the eim lope of a balloon or in the wing of an acr,. plane to allow inspection of the interior, or of aileron controls when the latter are mounted inside an aero foil section. INSTABILITY An inherent condition of a body, which, if tin- body is distributed, causes it to move toward a position away from its first position, instead of returning to a condition of equilibrium. KEEL PLANE AREA The total effective area of an air- craft which acts to prevent skidding or side slipping. KITE A form of aircraft without other propelling menus than the tow-line pull, whose support is derived from the force of the wind moving past its surfaces. LANDING GEAR The understructure of an aircraft de- signed to carry the load when resting on. or running on, the surface of the land or water. LEADING EDGE (See KNTKHISI; KIIOK.) LEEWAY The angle of deviation from a set course over the earth, due to cross currents of wind. Also called Drift. LIFT The component of the force due to the air pres- sure of an aerofoil resolved perpendicular to the flight path in a vertical plane. LIFT BRACING (See STAY.) LIFT-DRIFT RATIO The proportion of lift to drift is known as the lift-drift ratio. It expresses the effi- ciency of the aerofoil. LOAD Draii The structure, power plant and essential acces- sories of an aircraft. fill The maximum weight which an aircraft can support in flight; the gross weight. 1'irful The excess of the full load over the dead weight of the aircraft itself, i. e., over the weight of its structure, power plant and essential accessories. (These last must be specified.) (See Capacity.) LOADING The weight carried by an aerofoil, usually 320 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING expressed in pounds per square foot of superficial area. LOBES Bags at the stern of an elongated balloon de- signed to give it directional stability. LONGERON The principal fore-and-aft structural mem- bers of the fuselage or nacelle of an airplane. (See LONGITUDINAL.) LONGITUDINAL A fore-and-aft member of the framing of an aeroplane body, or of the float in a seaplane, usually continuous across a number of points of sup- port. LONGITUDINAL DIHEDRAL (See DIHEDRAL.) MAST (See HORN.) MONOCOQUE (See BODY.) MONOPLANE A form of aeroplane whose main support- ing surface is a single wing extending equally on each side of the body. (See AEROPLANE.) MOORING BAND The band of tape over the top of a balloon to which are attached the mooring ropes. NACELLE (See BODY.) NET A rigging made of ropes and twine on spherical balloons, which supports the entire load carried. NOSE DIVE A dangerously steep descent, head on. NOSE PLATE A plate at the nose or front end of the fuselage in which the longerons terminate. NOSE SPIN A nose dive in which the aeroplane rotates about its own axis due to the reaction from the pro- peller. It usually results from failure to shut off the engine in time when going into a nose dive, and is likely to cause complete loss of control. ORNITHOPTER A form of aircraft deriving its support and propelling force from flapping wings. OUT-RIGGER Members, independent of the body, ex- tending forward or to the rear and supporting con- trol or stabilizing surfaces: OVERHANG The distance the wings project out beyond the outer struts. PAN CAKE, To To descend as a parachute after a ma- chine has lost forward velocity. To strike the ground violently without much forward motion. PANEL A portion of a framed structure between adja- cent posts or struts. Applied to the fuselage it is the area bounded by two struts and the longerons. An entire wing is often spoken of as a panel. Thus the upper lifting surface of a biplane is usually of three parts designated as the right upper panel, left upper panel and the center panel. PARACHUTE An apparatus made like an umbrella used to retard the descent of a falling body. PARASITE RESISTANCE The total resistance to motion through the air of all parts of an aircraft not a part of the main lifting surface. PATCH SYSTEM A system of construction in which patches or adhesive flaps are used in place of the suspension band in a balloon. PERMEABILITY The measure of the loss of gas by diffu- sion through the intact balloon fabric. PHILLIPS ENTRY A reverse curve on the lower surface of an aerofoil, towards the entering edge, designed to more evenly divide the air. PITCH OF A PROPELLER (See PROPELLER.) PITCH OF A SCREW The distance a screw advances in its nut in one revolution. PITCH, To To plunge in a fore-and-aft direction. PITOT TUBE A tube with an end open square to the fluid stream, used as a detector of an impact pres- sure. It is usually associated with a concentric tube surrounding it, having perforations normal to the axis for indicating static pressure; or there is such a tube placed near it and parallel to it, witli a closed conical end and having perforations in its side. The velocity of the fluid can be determined from the difference between the impact pressure and the static pressure, as read by a suitable gauge. This instru- ment is often used to determine the velocity of an aircraft through the air. PLANE OF SYMMETRY A vertical plane through the longitudinal axis of an aeroplane. It divides the aeroplane into two symmetrical portions. PONTOON (See FLOAT.) PROPELLER OR AIR SCREW A body so shaped that its rotation about an axis produces a thrust in the di- rection of its axis. Disc-Area of Propellet The total area of a circle swept by the propeller tips. Pitch Of The distance a propeller will advance in one revolution, supposing the air to be solid. Race The stream of air driven aft by the propeller and with a velocity relative to the aeroplane greater than that of the surrounding body of still air. (Fre- quently called slip-stream.) Slip Of The difference between the distance a pro- peller actually advances and the distance it would advance while making the same number of revolu- tions in a solid medium. Usually expressed as a per- centage of the total distance. Torque Of The turning moment of the propeller. The effect of propeller torque is an equal reaction tending to rotate the whole aeroplane in the oppo- site direction to that of the propeller. PUSHER (See AEROPLANE.) PYLON A post, mast or pillar serving as a marker of a flying course. Also used infrequently to designate the control masts such as the aileron mast, rudder mast, elevator mast, etc. RAKE The angular deviation of the outer end of a wing from a line at right angles to the entering edge. RELATIVE WIND The motion of the air with reference to a moving body. Its direction and velocity, there- fore, are found by adding two vectors, one being the velocity of the air with reference to the earth, the other being equal and opposite to the velocity of the body with reference to the earth. RETREAT (See SWEEP BACK.) RIB A member used to give strength and shape to an aerofoil in a fore-and-aft direction. Web A light rib, the central part of which is cut out in order to lighten it. Compression A rib heavier than the web type and so constructed as to resist the compression due to the wire bracing of the aeroplane. Secondary Nose Small ribs extending from the front spar to the nose strip (entering edge). Placed be- No.MKNt LATt UK 1O|{ AERONAUTICS .!_ i tween tin- iii.iin rilis to give Mi|i|inrt to the fal.ru n, ..r tin- entering edge. Sometimes called Stuli Hibs. J(K,(.I.\(, Tin- art (if truing up .-in aeroplane ;nitrip in tin- upper part of a balloon which i* torn off" when immediate deflation is desired. Hi DIIKH A hinged or pivoted Mirf-ice, usually more or li -ss flat or streamlined, used for the purpose of eon trolling the attitude of an aircraft about its vertical axi.s, i. e., for controlling its lateral movement. KriMiKii BAH A bar pivoted at the center, to the ends of which the rudder control cables are attached. The pilot operates the rudder by moving the rudder bar With his feet. lit iiixii POST Tin- post to which the rudder is hinged, generalh forming the rear vertical member of the vertical staliili/er. Sr \ PLANE An aeroplane fitted with pontoons or floats suitable for alighting on or rising from the water. (See AEROPLANE.) SERPENT A short heavy guide rope used with balloons. SIHXINO A binding of wire, cord or other material. I'siially used in connection with joints in wood, and cable splices. SIHK Si. i PIMM. Sliding sideways and downward toward the center of a turn, due to an excessive amount of bank. It is the opposite of skidding. SIM U'ALK A reinforced portion of the wings near the fuselage serving as a support in climbing about the aeroplane. Otherwise known as running board. SKIDDING Sliding sideways away from the center of a turn, due to an insufficient amount of bank. It is the opposite of side slipping. SKIDS LANDING GEAR Long wooden or metal run- ners designed to prevent nosing of a land machine when landing, or to prevent dropping into holes or ditches in rough ground. Generally designed to function in case the wheels should collapse or fail to act. ]- a i[ A skid supporting the tail of a fuselage while on the ground. H'ing A light skid placed under the lower wing to prevent possible damage on landing. SKIS FRICTION Friction between the air and a surface over which it is passing. SUP STREAM (See PROPELLER RACK.) SOMIIM; MAI IIINE (See GLIDER.) BPAN-WING Span is the dimension of a surface across the air stream. If ing Span or Spread of a machine is length overall from tip to tip of wings. SPARS-WING Long pieces of wood or other material forming the main supporting members of the wing, and to which the ribs are attached. SPHKAD (See SPAN.) STABILITY The quality of an aircraft in flight which causes it to return to a condition of equilibrium after meeting a disturbance. Directional That property of an aeroplane by virtue of which it ten. Is t.. hold a straight course. That is. if a machine ti mis constantly to xeer ori its course "< ..I the controls by the pilot to keep it on its course, it is said to lack directional stability . Dynamical The quality of an aircraft in flight which causes it to return to a condition of equilibrium after its attitude has been changed In mii.ui;> ...m. di> turbance, e. g., a gust. This return to equilibrium is due to two factors; first, the inherent righting mo- ments of the structure; second, the damping of the oscillations In the tail, i tc. Inherent Stability of an aircraft due to the disposi lion and arrangement of its fixed parts, i. e.. that property which causes it to return to its normal atti- tude of flight without the use of the controls. Lateral The property of an aeroplane by virtue of which the lateral axis tends to return to a horizontal position after meeting a disturbance. Longitudinal An aeroplane is longitudinally stable when it tends to fly on an even keel without pitch- ing or plunging. Statical In wind tunnel experiments it is found that there is a definite angle of attack such that for a greater angle or a less one the righting moments are in such a sense as to tend to make the attitude re- turn to this angle. This holds true for a certain range of angles on each side of this definite angle; and the machine is said to possess " statical stabil- ity " through this range. STABILIZER Balancing planes of an aircraft to promote stability. Horizontal A horizontal fixed plane in the empan- nage designed to give stability about the lateral axis. J'ertical A vertical fixed plane in the empannage to promote stability about the vertical axis. Mechanical Any mechanical device designed to se- cure stability in flight. STABILIZING FINS Vertical surfaces mounted longi- tudinally between planes, to increase the keel plane area. STAGGER The amount of advance of the entering edge of a superposed aerofoil of an aeroplane, over that of a lower, expressed as a percentage of the gap. It is considered positive when the upper aerofoil is for- ward. STALLING A term describing the condition of an aero- plane which, from any cause, has lost the relative speed necessary for steerageway and control. STATION The points at which struts join the longerons in a fuselage, are termed stations and are numbered according to some arbitrary system. Some makers begin with No. 1 at the nose plate aiiH number to- ward the rear. Other makers begin with at the tail post and number toward the front. STATOSCOPE An instrument to detect the existence of a small rate of ascent or descent, principally used in ballooning. STAY A wire, rope, or the like used as a tie piece to hold parts together, or to contribute stiffness; for example, the stays of the wing and body trussing. STREAMLINE-FLOW A term used to describe the cmidi 322 TEXTBOOK OF APPLIED AERONAUTIC ENGINEERING tion of continuous flow of a fluid, as distinguished from eddying flow, where discontinuity takes place. STREAMLINE-SHAPE A shape intended to avoid eddying or discontinuity and to preserve streamline-flow, thus keeping resistance to progress at a minimum. STRINGERS A term applied to the slender wooden mem- bers running laterally through the wing ribs for the purpose of stiffening them. STRUT A compression member of a truss frame; for in- stance, the vertical members of the wing truss of a biplane. STRUT-INTERPLANE A strut holding two aerofoils. SUPPORTING SURFACE Any surface of an aeroplane on which the air produces a lift reaction. SUSPENSION BAND The band around a balloon to which are attached the basket and the main bridle suspen- sions. SUSPENSION BAR The bar used for the concentration of basket suspension ropes in captive balloons. SWEEP-BACK The horizontal angle between the lateral (athwartship) axis of an aeroplane and the entering edge of the main planes. TACHOMETER An instrument for indicating the number of revolutions per minute of the engine or propeller. TAIL CUPS The steadying device attached at the rear of certain types of elongated captive balloons. TAIL-NEUTRAL A tail, the horizontal stabilizer of which is so set that it gives neither an upward lift nor a downward thrust when the machine is in normal flight. Positive A tail in which the horizontal stabilizer is so set as to give an upward lift and thus assist in carry- ing the weight of the aeroplane when it is in normal flight. Negative One in which the horizontal stabilizer is so set as to give a downward thrust on the tail when the machine is in normal flight. TAIL POST The vertical strut at the rear end of the fuselage. TAIL SKID A skid supporting the tail of a fuselage while on the ground. TAIL SLIDE A steep descent, tail downward. Usually caused by stalling on an attempt to climb too steeply. THIMBLE An elongated metal eye spliced in the end of a rope or cable. TRACTOR (See AEROPLANE.) TRAILING EDGE The rearmost portion of an aerofoil. TRIPLANE A form of aeroplane whose main supporting surface is divided into three parts, superimposed. TRUSS The framing by which the wing loads are trans- mitted to the body ; comprises struts, stays and spars. UNDERCARRIAGE (See LANDING GEAR.) VETTING The process of sighting by eye along edges of spars, planes, etc., to ascertain their alignment. An experienced man can detect and remedy many faults in alignment by this method. VOL-PIQUE' (See NOSE DIVE.) VOLPLANE To glide. WARP To change the form of the wing by twisting it, usually by changing the inclination of the rear spar relative to the front spar. WASHIN A progressive increase in the angle of inci- dence from the fuselage toward the wing tip. WASHOUT A progressive decrease in the angle of inci- dence from the fuselage toward the wing tip. WEIGHT-GROSS (See LOAD, FULL.) WINGS The main supporting surfaces of an aeroplane. Also called Aerofoils. WING FLAPS (See AILERON.) WING LOADING (See LOADING.) WING MAST The mast structure projecting above the wing, to which the top load wires are attached. WING RIB A fore-and-aft member of the wing structure used to support the covering and to give the wing section its form. (See RIB.) WING SPAR OR WING BEAM A transverse member of the wing structure. (See SPARS-WING.) WIRES Drift Wires that take the drift load and transfer it through various members to the body of the aero- plane. Flying The wires that transfer to the fuselage, the forces due to the lift on the wings when an aeroplane is in flight. They prevent the wings from collapsing upwards during flight. Landing The wires that transfer to the fuselage, the forces due to the weight of the wings when an aero- plane is landing or resting on the ground. Staggei The cross brace wires between the inter- plane struts in a fore-and-aft direction. YAW To yaw is to swing off the course and turn about the vertical axis owing to side gusts of wind or lack of directional stability. Angle Of The temporary angular deviation of the fore-and-aft axis from the course. ACCELERATION The rate of increase of velocity. CENTER OP GRAVITY The center of gravity of a body is that point about which, if suspended, all the parts will be in equilibrium, that is, there will be no tend- ency to rotation. CENTRIFUGAL FORCE That force which urges a body, moving in a curved path, outward from the center of rotation. COMPONENT A force which when combined with one or more like forces produces the effect of a single force. The single force is regarded as the resultant of the component forces. DENSITY Mass per unit of volume; for instance, pounds per cubic foot. EFFICIENCY (Of a machine.) The ratio of output to input of power, usually expressed as percentage. ELASTIC LIMIT The greatest stress per unit area which will not produce a permanent deformation of the ma- terial under stress. ELONGATION When any material fails by tension it usually stretches and takes a permanent set before it breaks. The ratio of this permanent elongation to the original length, expressed as a percentage, is a measure of the elongation. ENERGY The capacity of a body for doing work. Hc.it is a form of energy. Any chemical reaction that gen- erates heat or electricity liberates energy. Bodies NOMENCLATURE 1O1{ .\KMo.\.\l IKS in i;. piissi ,s i 111 rax |i\ virtue of liixinu work done ii|inii tin in I viiiiiiiiMM \\lnn tun or more turns u-t upon a hodx in such .1 wax that im iiuitiuii results, then i> saiil I" IM- equilibrium. I I xi i"ii "i >\ihix Tin ral in of tin- load required to : nliiri- in n slnu-tur.-il member to tin- usual uorkmg load tin- member is designed In carrx. Thus if a ini-iiilii-r hr designed to carry a loud t ..mi Ihs. nnd it would require a load of -JIMIII His. to cause fail- ure, the factor of .safety would lie four. I -"I I'. MM) The foot pound is n unit of work. It is equal to a force of one pound acting through a dis taiicc of one foot. This is a font pound nl energy. ISHITM That property of a body by virtue of which it resists any attempt to -start it if at rest, to stop it if in motion, or in any wax to cli.mge either the direction or xilocity of motion, is called Inrrlia. M x-s The mass of a body is a measure of the quantity of material in it. MMXHNI Moment is the product of n force times its lexer arm. It is usually expressed in Inch-I'oundi. \lo\u NII \i Momentum is the product of the mass and velocity of a moving body. It is a measure of the quantity of motion. POWER Power is the time rate of doing work. llnrir power The horsepower is a unit of work. One horsepower represents the performance of work at the rate of 33,000 foot-pound* per minute, or 550 foot pounds per second. RESTLTANT OF A FORTE The resultant of two or more forces is that single force which will produce the same effect upon a body as is produced In the joint action of the component forces. STRK*S The internal condition of a body under the ac- tion of opposing forces. The unit of measure is usually pounds per square inch. Comprrttion When forces are applied to a body in such n war as to tend to crush it, there results a com - prcssive stress in the body. Trntion When forces are applied to a body in such a way as to tend to separate or pull it apart, the Iwidx is said t.i I tension or a tensile stress has 1 i n produced within it. Shrur When external forces are applied in such a wax is ti> cause a tendency for particles of a body to slip or slide past each other, there results a sin ir mg stress in the hodx. > in \ix Strain is the deformation produced in a body by the application of external f"! ToHvi'K U In n forces are so disposed as to cause or tend to cause rotation, then- is produced a turning in nl which is also called tori|iie. It is usually measured in inch pounds. Thus if a force of 10 pounds be applied tangcntially to the rim of a wheel of lO-inch radius, the torque or turning moment will be KM) inch pounds. L'LTIMATE STRENGTH The load per square inch re- quircd to produce fracture. VELOCITY In uniform motion, the distance passed over in n unit of time, as one second. This may also be obtaitied hy dividing the length of any portion of the path hy the time taken to describe that portion, no matter how small or great. In variable motion, where velocity varies from (Miint to point, its value at any point is expressed as tin- quotient of an infinitely small distance, containing tin- given point hy the infinitely small portion of time in which this distance is described. WORK The product of a force by the distance described in the direction of the force by the point of applica- tion. If the force moves forward it is called a work- ing force, and is said to do the work expressed hy this product; if backward, it is called a resistance, and is then said to have the work done upon it, in overcoming the resistance through the distance men- tioned (it might also be said to have done negative work). In a uniform translation, the working forces do an amount of work which is entirely applied to overcom- ing the resistance*. The Metric System The Metric System The fundamental unit of the metric system is the METER (the unit of length) From this the units of mass (GRAM) and capacity (LITER) are derived. All other units are the decimal subdivisions or multiples of these. These three units are simply related, so that tc all practical purposes the volume of one kilogram of water (one liter) iv , (jiial to mi'- cubic decimeter. One short ton equals ahout .91 metric ton; one long ton equals abou 1.02 metric tons, and one kg. equals about 2.20 pounds. EQUIVALENTS 1 METER = 39.37 INCHES PREFIXES MEANING UNITS Legal Equivalent Adopted by Act of Congress, July 28, 1866. MILLI- =; one thousandth Viooo -001 CENTI- = one hundredth Moo .01 METER for length Length DEC1 one tenth Via -1 unit : me 1- GRAM for mass Centimeter Meter r 0.3937 3.28 inch feet IllcTO- = on" hundred lK 100. LITER for capacity Meter Kilometer = 1.094 0.621 yards statute mile KILO- one thousand i 1000. Kilometer = 0.5396 nautical mile The metric terms are formed by combining the words "METER, Inch Foot _ 2.540 0.305 centinit ters meter "GRAM," and "LITER" with the six numerical prefixes. Yard 0.914 meter Length Statute mile 1.61 kilometers 10 milli-meters mm = 1 centimeter cm Nautical mile = 1.853 kilometers 10 centi-meters 1 deci-meter dm . 10 deci-meters = 1 METER (about 40 inches) m Area 10 meters = 1 deka-meter dkm Sq. centimeter 0.155 sq. inch 10 deka-meters = 1 hectometer Sq. meter 10.76 sq. fiet 10 hecto-meters 1 kilo-meter (about % mile) km Sq. meter 1.196 sq. yards Mass Hectare =: 2.47 acres 10 milligrams mg =1 centi-gram eg 10 centi-grams = 1 deci-gram dg 10 deci-grams 1 GRAM (ahout 15 grains) g 10 grains = 1 deka-gram dkg 10 deka grams = 1 hecto gram hg 10 hecto-grams = 1 kilogram (about 2 pounds) kg Sq. kilometer Sq. inch Sq. foot Sq. yard Acre Sq. mile = 0.386 6.45 0.0929 0.836 0.405 2.59 sq. mile sq. centimeters sq. meter sq. meters hectare sq. kilometers Capacity Volume 10 nulli-liters ml =1 ccnti-liter cl Cu. centimeter = 0.0610 cu. inch 10 centi-liters = 1 deci-liter dl Cu. meter 35.3 cu. feet 10 deci-liters = I LITER (ahout 1 quart) Cu. meter 1.308 cu. yards 10 liters = 1 deka-liter dkl Cu. inch 16.39 cu. centimeters 10 deka-liters = 1 hecto-liter (ahout a barrel) hi Cu. foot 0.0283 cu. meter 10 hecto-liters = 1 kilo-liter kl Cu. yard = 0.765 cu. meter The square and cubic units are the squares and cubes of the Capacity linear units. The ordinary unit of land area is the HECTARE (ahout 2% acres). Milliliter 0.0338 U. S. liq. ounce Length Milliliter Liter _ 0.2705 1.057 apoth. drain U. S. liq. quarts 1.000 millimeters (mm) or 100 centimeters (cm) = 1 meter (m). 1.000 m = 1 kilometer (km). Liter Liter Dekaliter z! 0.2642 0.908 1.135 U. S. liq. gallon U. S. drv quart U. S. pecks Capacity Hectoliter 2.838 U. S. bushels 1,000 milliliters (mil) or cubic centimeters (cc) 1 liter (1). 1,000 1 = 1 kilometer (kl) or cubic meter (cm m). U. S. liq. ounce U. S. apoth. dram U. S. liq. quart zT 29.57 3.70 0.946 milliliters milliliters liter Weight U. S. dry quart = 1.101 liters U. S. liq. gallon 3.785 liters 1,000 milligrams (mg) = 1 gram (g). U. S. peck - 0.881 dekaliter 1.000 g= 1 kilogram (kg). 1.000 kg = 1 metric ton. U. S. bushel 0.3524 hectoliter A dollar is divided into 100 cents or 1,000 mills, just as the meter is divided into 100 centimeters or 1,000 millimeters. And as, for Weight example, 2 dollars and 25 cents is written $2.25, so 2 meters and 25 rrntimeters is conveniently written 2.25m. Meters, liters and grams are treated in the same way as dollars. For practical purposes, from Gram Gram = 15.43 0.772 grains U. S. apoth. scruple units of length are formed the squares, cubic or capacity measures (a cubic measure 10 cm. on each edge, or 1,000 cc., makes 1 liter) and Gram Gram ii 0.2572 0.0353 U. S. apoth. dram avoir, ounce the weights (1 cc. of water weighs 1 gram). Gram Kilogram = 0.03215 2.205 troy ounce avoir, pounds Length Kilogram zr 2.679 troy pounds For all practical purposes 3 feet and 3% inches equal 1 meter or 100 centimeters, and 1 inch equals 2.5 cm. The exact legal equiva- lent for the United States is 39.37 inches to 1m. Metric ton Metric ton Grain U. S. apoth. scruple = 0.984 1.102 0.0648 1.296 gross or long ton short or net tons grams grams Capacity U. S. apoth. dram 3.89 grams One liter equals 1.0567104 liquid quarts or ahout .91 dry quart. Avoir, ounce 28.35 grams One fluid ounce equals about 29.57 milliliters or cc. Troy ounce 31.10 Jrams Weight Avoir, pound 0.4536 ilogram Troy pound 0.373 kilogram In avoirdupois weight one ounce equals nearly 28.25 grams; one Gross or long ton 1.016 metric tons pound, exactly 453.5924277 g. nearly 454 g. or 454 kg. Short or net ton 0.907 metric ton LENGTHS INCHES MILLI- METERS INCHES CENTI- METERS FEET METERS U. S. Yards METERS U..S. Miles KILO- METERS 0.03937 1 0.3037 1 1 = 0.304801 1 - 0.914402 0.62137 = 1 0.07874 2 0.7874 = 2 2 = 0.609601 1 093611 1 1 1.60935 0.11811 3 1 J..")4001 3 - 0.914402 2 1.828804 1.24274 = 2 0.15748 4 1.1811 = 3 3.28083 = 1 2.187222 2 1.86411 = 3 0.19685 6 1.5748 = 4 4 = 1 219202 3 2.743205 2 3.21869 0.23622 6 1.9685 = 5 5 = 1.524003 3.280833 3 2.48548 = 4 0.27559 7 2 = 5.08001 6 = 1.828804 4 3 657607 3 = 4.82804 0.31496 8 2.3622 = 6 6.56167 = 2 4.374444 4 3.10685 = 5 0.35433 9 2.7559 = 7 7 = 2.133604 5 4.572009 3.72822 = 6 1 25,4001 3 7.62002 8 = 2.438405 5.468056 5 4 6.43739 2 50.8001 9 =: 2.743205 6 5 486411 4.34959 = 7 3 76.2002 3.5433 = 9 9.84250 = 3 6.561667 - - 6 4.97096 = 8 4 101.6002 4 = 10.16002 13.12333 = 4 7 6 400813 5 8.04674 6 127.0003 5 = 12.70003 16.40417 = 6 7.655278 _ 7 5.59233 = 9 6 152.4003 6 == 15.24003 19.68500 = 6 8 7 315215 6 9.65608 7 177.8004 7 17.78004 22.96583 8.748889 . 8 7 11.26541! 8 203.2004 8 20.32004 26.24667 g 9 _ 8 229616 8 12.8747H 9 22S.6005 9 - 22.86005 29 52750 = 9 9.842500 -- 9 9 14.48412 324 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO SO CENTS ON THE FOURTH DAY AND TO $1.OO ON THE SEVENTH DAY OVERDUE. JAN 25 1934 Jfctt 26 NOV 24 ' ^Y USE 14 1953 LD21-100m-7,'33 YE 018' 7 o UNIVERSITY OF CALIFORNIA UBRARY