B 16/009 * Simplified Tefinitions 3 of / 3-2 /? 44.2 and |lomenclature for fleronautics 1942 Illustrated €dition Lieut. Leslie Thorpe #! Wlodern fleronautical %Dictionary Simplified Definitions and |lomenclature for fleronautics 1942 Illustrated €dition © - Lieut. Leslie Thorpe fl ||lodern fleronautical T)ictionary Yast Engin. Library 7T/_ J -? sº º," " --~ 2- -3 * --) …” / ~...~" r * ... r º f - - - - * 3"... -...- Copyright 1931 by Aviction Press Sqn Francisco, Calif. 1942 Illustroſted Edition Copyright 1942 by Aviation Press San Froncisco, Calif. AVIATION PRESS 580 Morrket Street San Francisco, California, U. S. A. Price $2.00 Aes .* - * * s º - a. * # , / - A tº ºr * : * * > ſ* g à & .*\---...- ~} * . . . 3. " * . . 3. ** *... . . . • * * * * * S." --" INTRODUICTION Simplified Definitions and Nomenclature for Aeronatics contains about one thousand five hundred definitions and explanations of words, parts, uses, factors, and features which occur in the study of the various subjects and sciences related to aeronautics. The foundation of this book is based on The Nomenclature for Aeronautics, Report No. 240, by The National Advisory Committee for Aeronautics. The alphabetical nomenclature is reproduced in full, and º each item therefrom is marked with a star (*). Items marked with a dagger (t) are reprinted from The Air Commerce Regulations by the United States Department of Commerce. This book has been prepared as an authoritative reference for every- one interested in the study of aeronautics so that every word and phrase of aeronautical study may be understood. The definitions are given in * the form of their direct application to aeronautics and related subjects, and do not, therefore, cover the general meaning of the words. In considering any particular definition it is advisable to make cross references to the principal words, phrases, and main headings which ap- pear in the definition. Also, use a modern dictionary. Simplified Definitions and Nomenclature for Aeronautics will be found invaluable for review work prior to examinations on any of the following subjects: AERODYNAMICS ENGINES THEORY OF FLIGHT IGNITION DESIGN ELECTRICITY MATERIALS MAGNETISM METALS CARBUIRETION CONSTRUCTION NAVIGATION RIGGING METEOROLOGY PARACHUITES INSTRUMENTS ACROBATICS FLIGHT MANEUIVERS WELDING PREFACE TO 1942 ILLUSTRATED EDITION *t is the hope and belief of the author and publisher that the extensive illustrating added to this new 1942 edition will greatly enhance the usefulness of this Standard Reference Work. Very complete and extensive drawings have been incor- ported to illustrate major definitions, and many items appear on the illustrations which are not defined in the immediate alphabetical location of the illustration. In most cases, however, many of these items are defined in the book, and readers are urged to seek out such definitions in the usual alphabetical way. CADE SYSTEM DUCATION IS DEFENSE ST PUBLISHED : Ił’ e s t e r n F l y l n q O c to be r , 194 1 “Light Aircraft Perform- ºnce Calculation” by Juan (lein Serralles. , 67 pages. wblished by Aviation Press, 80 Market Street, San Fran- risco, Calif. This text is a Cadet Series publication and careful ap- plication of the methods ex- plained should enable the stu- dent to give his ideas prac- tical form and render esti- mates of the results he may expect with an accuracy that guess work could never attain. Although based on the as- sumption that the reader has at least an elementary knowl- edge of mathematics and the fundamental principles of aerodynamics, the author has necessary mathematical ma- terial in a form which though simplified, in no way sacri- fices accuracy. The (J A D ET SYSTEM is iſ 0147 A E R O NAUT'ſ C.A. H., UNIVERSITY Mechanical Engineering, August, 1941 *RoceDURE HANDBook For AIRCRAFT STRESS ALYsis. By W. L. Nye, D. Hamilton, and P. Eames. Aviation Press, San Francisco, if., 1940. Paper, 7/2 × 9°/, in., 334 PP. , ls., diagrams, charts, tables, $4. This text- bk was compiled to present as simple a treat- nt as possible on the subjects of strength materials and stress analysis as applied to : present-day airplane. It deals with the ldamentals of aircraft stress analysis and sents examples which are currently encoun- ed in conventional airplane-design work. rticular attention is given to the solution beams by polar diagrams, the shell typc structure, and the theory of joints. JUST PUBLISHED: PRACTICAL THERMODYNAMICS for AIRCRAFT ENGINES By Lieut. Leslie Thorpe Price $3.50 A Mechanics Manual—A College Texf COMING JANUARY FIRST: SIMPLIFIED DEFINITIONS & NOMENCLATURE FOR AERONAUTICS –1942 illustrated Edition—A Modern Aeronautical Dictionary. By Lieut. Leslie Thorpe. Price $2.00 Coming February 1, 1942 MANUAL for AIRCRAFT HYDRAULICS By Rodney B. Campbell and James G. Thompson Price $4.00 THE NEW CADET SYSTEM A TEXT BOOK ON AVIATION. By Lt. Leslie Thorpe Volume 1–Aerodynamics and Theory of Flight. Volume 2—Materials, Construction, Rigging, and Civil Air Regulations. Volume 3—Engines, Ignition, and Carburetion. Volume 4—Navigation and Meteorology. Radio Beam Flying. COMPLETE GROUND SCHOOL COURSE, $3.00 PER VOLUME THE CADET SERIES MODERN AIRCRAFT RADIO. By Willis L. Nye. Price $4.00 AVIATION SERVICE AND MAINTENANCE. By James G. Thompson. Price $3.00 AIRCRAFT MANUAL FOR INSPECTION, MAINTENANCE AND REPAIR. By Jack Linckle, Lieut., U.S.N.R. Price $3.50 METAL AIRCRAFT & DESIGN CONSTRUCTION. By Willis L. Nye. Price $3.00 NAVIGATION PACKAGE. Small fools for chart work. (Parallel rulers, protractor, dividers, scale and pencil.) Price $3.50 THE CADET ENGINEERING SERIES ELEMENTARY AIRPLANE STRUCTURAL ANALYSIS BY GRAPHIC METHODS. By Lieut. James P. Eames. Price $3.00 PRACTICAL AERONAUTICAL ENGINEERING. By Willis L. Nye. Price $4.00 AiRCRAFT DRAFTING ROOM MANUAL. By James G. Thompson. Price $3.50 PROCEDURE HANDBOOK FOR AIRCRAFT STRESS ANALYSIS. By Nye- Hamilton-Eames. Price $4.00 LIGHT AIRCRAFT PERFORMANCE CALCULATION. By Juan Klein Serrallés. Price $2.00 OBRAS DE AERONAUTICA EN CASTELLANO CALCULOS DE PERFORMANCE DE LAS AVIONETAS, por Juan Klein Serrallés, Ing. Ae.—Precio $2.00 EQUILIBRIO, ESTABILIDAD Y CONTROL DE LOS AEROPLANOS, por Juan Klein Serrallés, Ing. Ae.—Precio $2.00 DICCIONARIO DE AERONAUTICA, Español-Inglés e Inglés-Español, por C. T. Reid.—Precio $3.00 MANUAL DE AERODINAMICA, por Juan Serrailés, Ing. Ae.—Precio $3.00 DEPT. P, 580 MARKET STREET AVIATION PRE SS, SAN FRANCISCO, GALIFORNIA mºmºmºs s J O U R N A L OF T H E A E R O N A U T I C A L S C I E N C E S Elementary Airplane Structural Analysis by Graphic Methods, by JAMES P. EAMES, Aviation Press, San Francisco, 1938; 180 pages, $3.00. (Loose leaf lithographed.) This book is a simplified text dealing with the methods of stress analysis of airplane structures within reach of the aero- nautical engineering student and the aircraft factory draftsman. The first chapter is a review of elementary graphics and me- chanics. There follow chapters on the characteristics of wood and metal airplane members, airworthiness requirements, fuselage structural analysis, wing truss structural analysis, and structural analysis of control members. Appendices treat various specialized subjects, such as stagger loads, the equation of three moments, the method of least work. A typical examination and a questionnaire are given at the end along with a glossary of terms. The selected illustrative design problem which is projected throughout the latter chapters treat features of the analysis of a framed biplane structure. The biplane arrangement was selec- ted as it represents a more complicated structure than the mono- plane type, and the student with a knowledge of the principles can easily pass to the monoplane analysis. The many figures are excellent and the description of the meth- ods is well done. Although the treatment is not always rigorous the scope and general methods are given. Practical Aeronautical Engineering, by WILLIs L. NYE, Aviation Press, San Francisco, 1938; 187 pages, $4.00. (Loose- leaf lithographed.) This book is designed to “serve as an intermediate text for the student engineer actively interested in modern airplane construc- tion.” It is intended as a continuation for the student who has digested “the Cadet System” by Leslie Thorpe (same publisher.) The subjects covered include aircraft design procedure, airfoil data, aerodynamic factors in design, parasite resistance data, stability, control and control surfaces, propellers, aircraft engi- neers and installation problems, landing gears, performance cal- culations, high performance aircraft, economics of aircraft struc- ture, and weight control. There are 164 excellent figures and the data compiled in 145 tables should find ready use. M A R C H | 93 9 The Yonkers Record, Saturday, January 28, 1939 NEW TECHNICAL BOOKS METAL AIRCRAFT, DESIGN AND CON- STRUCTION, by Willis L. Nye; Aviation Press, San Francisco, Calif.-Nye's new book takes cognizance of the trend toward all-metal construction in avia- tion, and treats upon it not only exhaustively, but in a practical manner to make for understanding. He discusses the rlative merits of each type of con- struction, tooling arid production methods used in the U. S., minor metal airplane parts, metal Weights, etc. Almost 250 graphic illustrations en- hance the volume further. AIRCRAFT MANUAL FOR INSPECTION, MAINTENANCE AND REPAIR, by Ensign Jack Lincke, Aviation Press, San Francisco, Calif.-This big book offers complete instructions for taking care of Sea, land and amphibians of 1, 2 and 3 engines, including all aircraft and engine ment. Over 125 drawings and photos illustrat salient points of the latest type airplanes an gines, and Lincke has included as well a method of fabric repair and prevention of e sion in welding fuel tanks. THE NEW CADET, SYSTEM SCHOOL TRAINING, by Lt. Leslie Thorpe; tion Press, San Francisco, Calif.-This new Considerably revised edition of a now well- work is still the best available for the stude aeronautics. Lt. Thorpe treats to the smallest tail on flight. Construction, engines, navigation other technical and mathematical matters. work, like the others, is illustrated and p moderately. It should be noted also by the and high school teacher as well as student. £ook houſewa Aviation Service and Maintenance, James G. Thompson, Size, 9 by inches. Cardboard, 161 p a ges. Ill trated, $3.00. A Cadet Series Publicati Aviation Press, 580 Market Street, S Francisco, Calif. The “Aviation Service and Mai tenance” articles which have appear in Western Flying for the past sev years form the basis of the latest avi tion book, published under the sa title in response to popular demand fr the followers of this long series of ticles. Complete revisions of all publish service articles of the author, James Thompson, have been included as pa of this 150,000 word volume, togeth with extensive additions of entirely me material, to form a complete text practical aviation mechanics. It ca truthfully be said that the larger po tion of the information in this book h not been available anywhere befor while most of the remainder has bee scattered through countless engine an airplane instruction manuals buried dee in a mass of irrelevant material. Written to augment, rather than t supplant the manuals of engine and air plane manufacturers, this book gives i condensed form the technical informa tion needed. for service and maintenanc operations pertaining to specific popula engines and airplanes, and contains a additional wealth of practical servic, and maintenance information. OF GR. enculuſ <hcraft Co. IN CORPORATED 2– MENOMINEE -- MICHIGAN Aviation Press May 15, 19||l 580 Market Street San Francisco, Calif. Dear Sir? I would like to obtain a new cover for the book "Practical Aeronautical Engineering" by Willis L. Nye. Please Send C.O.D. I have most of the Cadet Engineering Series as handled by Air Associates and find them to be "the best available. I would appreciate knowing about any books that you may plan to add to this series and any you have available on mathematics, especially if written in the style of the above series. Very truly yours, H. Edwa Moxle 3 Chief Draftsman Wichi Aviation Pre 3 8 i chita, Kan 3 as 580 Market, St, re et, June 9, 1941 San Franc is co, California De a r 3 i r : At present, I am employed in the in a pection department of the Stearm an Aircraft, Division of Boeing Airplane Company, here in Wichita. Therefore , it is need less for me to a ay that I have found the "Aircraft Draft ing Room Manual" by James G. Thomps on extremely useful in my work. I would like very much to have a copy of the Drafting Room Manual, and would deeply appreciate your 3 end in g, C.O.D., a copy of this manual to my home address. Thanking you since rely, I am Wery truly your 8, Fre der ic k M. Be a l & l l No. Lorraine St. Wich it a , Kans a 3 &ast Saint-Couis, Jllinois January 18, 194l Gentlemen: Please send me your catalogue of aviation publications. I have already purchased the "Procedure Handbook for Aircraft Stress Analysis" by Nye - Hamilton - Eames • I have found it, so satisfactory that I would like to add more of your aviation publications to my rapidly growing reference library Sincerely yours, .ſ.º.A. & Robert. He Le 3alent (allege #alent, #estabirginia to E P A R T M E N T C F C H E M I S T R Y A R T H U R B. G O U L. D. January l, l9ll Aviation Press 580 Market Street San Francisco, California Dear Sirs : I have seen a copy of your book "The New Cadet System of Ground School Training" by Lt. Leslie Thorpe. I like this book very much and would like to obtain a copy. I am especially interested in aviation and meteorology. Please let me know the price of the book. Yours truly, 22, ºz. 2/ Arthur B. Gould ABS SIMPLIEIED DEFINITIONS and |NOMENCLATUIRE FOR AERONAUITICS abscissas are the distances along the horizontal axes on curve diagrams or graphs. The vertical distances are called ordinates. “absolute inclinometer—See INCLINOMETER, ABSOLUTE. absorption—The process whereby heat waves are destroyed by the body they enter. absolute humidity—See HUMIDITY, ABSOLUTE. acceleration—The rate of change of velocity. If, at the end of each succeeding second, the velocity of an object is one mile per hour greater than at the end of the preceding sec- ond, then the acceleration of the object is one mile per second per second. This would be a case of uniformly accelerated motion. The acceleration has no relation to velocity itself, but only to the rate of change of velocity. accelerating well in a carburetor is a small well of fuel which is made available to the main jet for the richer mixture desired when the throttle is opened quickly. When the throttle is closed this well fills up so that it is always primed with fuel for sudden throttle openings. acceleration of gravity in feet per second per second is 32.17 at sea level at 45° latitude. The variation at other places is so small that it is negligible in ordinary calculations. acceleration, uniform—See UNIFORM ACCELERATION. *accelerometer—An instrument for indicating, measuring, or recording accelerations. acetylene is a colorless gas with a disagreeable odor which burns in air with a yellowish sooty flame. This dirty flame is apparent at the tip of a welding torch before the oxygen is turned on to neutralize the flame. adiabatic cooling—Air cools with ascent and heats with de- scent at the rate of approximately 1.6°F. per 300 feet. adjustable surface—See SURFACE, ADJUSTABLE. aerial train—One or more gliders towed behind an airplane. aerobatics are defined as intentional aerial acrobatics which are not necessary to air navigation, but which demonstrate the ability of the pilot and the strength, maneuverability and controllability of the airplane. "aerodynamic volume—See VOLUME, AERODYNAMIC (AIRSHIP). "aerodynamics—The branch of dynamics which treats of the motion of air and other gaseous fluids and of the forces acting on solids in motion relative to such fluids. aerology is that branch of physics which treats of the laws and phenomena of the atmosphere. "aeronautics—The science and art pertaining to the flight of aircraft. AER aerometer is a device for weighing the tension of air or other gases to determine weight and density. "aerostat — A generic term for aircraft whose support is chiefly due to buoyancy derived from aerostatic forces. The immersed body consists of one or more bags, cells, or other containers, filled with a gas which is lighter than air. Syn.—LIGHTER-THAN-AIRCRAFT, Includes airship and balloon, q.v. “aerostatics—The science that treats of the equilibrium of gaseous fluids and of solid bodies immersed in them. As an aeronautic term, it relates to those properties of lighter- than-air craft which are due to the buoyancy of the air. aerostation—The art of operating aerostats. aging, magnets is the subjecting of magnets to treatment sim- ilar to the treatment which will be encountered in service. The aged magnet will have less than the maximum strength obtainable, but this strength will continue un- changed over a long period. aging of metals refers to the spontaneous changes which take place in the metals after production and mechanical opera- tions are finished. Artificial aging may be employed, espe- cially in aluminum aging process, to secure greater hard- ness and strength. agonic lines—Lines on a chart or map joining places of zero variation. Such a line passes through the western tip of Michigan, bearing toward the southeast to the Atlantic Ocean through Indiana, Kentucky, Tennessee, and Georgia. *aileron—A hinged or pivoted movable auxiliary surface of an airplane, usually part of the trailing edge of a wing, the primary function of which is to impress a rolling moment on the airplane. "aileron angle—See ANGLE, AILERON. ailerons (differential) are ailerons which are hinged in such a manner that the raising of one aileron exceeds the droop- ing of the other. This action tends to equalize the drag of the ailerons. aileron (Frise type) is an aileron which is hinged some dis- tance back from the leading edge of the aileron in such fashion that when the aileron is drooped the action is normal, because the leading edge of the aileron is screened by the wing. However, when the aileron is raised, the leading edge projects below the under surface of the wing, thus introducing a drag force which tends to compensate the drag of the other drooped aileron against yawing. aileron, interplane is an aileron supported between two wings and not a part of the trailing edge of either wing. aileron (skew) is an aileron whose hinge line bears forward from the inner end of the aileron at the trailing edge and towards the wing tip at an angle of perhaps 10° or 15°. This arrangement places the bulk of the aileron area at the maximum distance from the longitudinal axis, thus Zézo/a Aogs Aryazazeze/czz Azoazza > * 72/4, 427A, d. | CTA/C 42–27 A/24.c7/2M 2A /27/ow /a Azezzzzz 72 Coe/ - * * * - - - - sº sº ºr - - - - * * * - - - - - * * * - - - - sº *sam - - - - -ºº ºme sº * - - - - -ºº º sº º- - Z af cº ºº: A Typical Group of Modern Airfoils. 7%f Z/A-7 24A//c/4/y/ly 4//za Azea A242 zazo De 472ea. AZ/Y&ZAF aſ AZ77 acaº Aze 3 OZ.4/7Zº // Aſ C.A. 2 2/2. 2– . A. C. A/. 24/2. / 2– /VA.C.A. 23 o? / //AW. C./7. 23/2 /YAZ CAP. Za/2 T- 2 ZAZ «. Az Z.4/5 ./4 = 2T. z_. A Group of Modern Conventional Airfoils. AIR giving extreme lateral control at high angles of attack. air bleed in a Stromberg carburetor is a channel opening which admits air to the fuel in the jets but below the fuel level. This action creates an emulsified condition of the fuel which leaves the main jet into the Venturi. air brakes are flaps on the side of the fuselage used to create air resistance for slower landings (experimental only). fair commerce means transportation in whole or in part by aircraft of persons or property for hire, navigation of air- craft in furtherance of a business, or navigation of aircraft from one place to another for operation in the conduct of a business. *air controls—See ContROLS. faircraft — Department of Commerce definition — Aircraft means "any contrivance now or hereafter invented, used or designed for navigation of or flight in the air, except a parachute or other contrivance designed for such naviga- tion, but used primarily as safety equipment." *aircraft—Any weight-carrying device or structure designed to be supported by the air, either by buoyancy or by dynamic action. *air duct—A tube, usually of fabric, supplying air for filling or for maintaining pressure in air-filled parts of an aeroStat. (a) The duct joining the vertical and lateral lobes of a kite balloon. Sometimes called "interconnecting sleeve" or “trousers" (British). (b) The duct leading from the air scoop or blower of a nonrigid or semirigid airship to the ballonet or ballonets. *airfoil—Any surface designed to be projected through the air in order to produce a useful dynamic reaction. *airfoil section (or profile)—A cross section of an airfoil made by a plane parallel to a specified reference plane. A line perpendicular to this plane is called the axis of the airfoil. air, gusty is caused by sudden increases and decreases in the wind velocity. This phenomenon should not be confused with the vertical action of convection currents. air line, or straight line, is the shortest distance between two points; therefore, air navigation, rather than air pilotage, effects a saving in time and expense over the casual method of following irregular landmarks. *air log-An instrument for measuring the linear travel of an aircraft relative to the air. One form consists of a wind- mill with a revolution counter. air navigation—Practice of the science necessary for con- ducting aircraft from a point of departure to a point of destination without regard to knowledge of intervening territory. fairman means any individual (including the person in com- mand and any pilot, mechanic, or member of the crew) who engages in the navigation of aircraft while under way, and any individual who is in charge of the inspection, AIR overhauling, or repairing of aircraft. air pilotage — The method of conducting aircraft from a point of departure to a point of destination, making use of known landmarks, such as towns, rivers, railroads, etc. *airplane—A mechanically driven aircraft, heavier than air, fitted with fixed wings, and supported by the dynamic action of the aif. airplane heading—See HEADING, AIRPLANE. *airplane, pusher—An airplane with the propeller or pro- pellers in the rear of the main supporting surfaces. *airplane, tandem—An air plane with two or more sets of wings of substantially the same area (not including the tail unit) placed one in front of the other and on about the same level. *airplane, tractor—An airplane with the propeller or pro- pellers forward of the main supporting surfaces. *airport—A locality, either of water or land, which is adapted for the landing and taking off of aircraft and which pro- vides facilities for shelter, supply, and repair of aircraft; or a place used regularly for receiving or discharging pas- sengers or cargo by air. air, pure, dry, is approximately 78% nitrogen, 21% oxygen, 1% argon and .03% carbon dioxide. air (standard)—Air at sea level at 59° F. and under normal barometric pressure of 29.92 inches of mercury (or 14.7 pounds per square inch). air (weight)—,0765 pounds per cubic foot under standard air conditions. “air scoop—A projecting scoop which uses the wind or slip stream to maintain air pressure in the interior of the bal- lonet of an aerostat. A similar device is sometimes used on airplanes to produce ventilation. air scoop (carburetor) is the flared opening or extension of the carburetor air intake designed to insure a large air supply to the carburetor. air screw, propeller—A surface so shaped that its rotation about an axis produces a force (thrust) in the forward direction of the axis. *airship—An aerostat provided with a propelling system and with means of controlling the direction of motion. When its power plant is not operating, it acts like a free balloon. nonrigid—An airship whose form is maintained by the internal pressure in the gas bags and ballonets. rigid—An airship whose form is maintained by a rigid Structure. semirigid—An airship whose form is maintained by means of a rigid or jointed keel in conjunction with internal pressure in the gas containers and ballonets. The term "airship" is sometimes incorrectly applied to heavier-than-air craft either in full or as "ship." This is a slang use of the word and should be avoided. “airship dope—See DOPE, AIRSHIP. “airship station—See STATION, AIRSHIP. ºueſduțw ułapow leoſdÃ_L e Jo uoņoºs-ssoap →ųL zvezza >>&zq ----/QN ~>&.*?> ºzvezave， z ºzeazzxºzzz！--->{±í！/* <-------------------------->>ez^ _zezzº :. ^� ^<）*J•* *， ** * * * * * * * • •_4.2%）/a/º? 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Zawodºº. ^/�NNJ `s,| | / /ºweraaer/\/OTAE YAWEYAO№s （37sº ^---''،^ºo^s^^^ -----’,’,^• Aº așryº`/%/z/. ^ ~5€/7 /vø/4 ----/ ,, ~--Oerayaer,^ k/ºveza/^/.e. – –~^ The Principal Parts of a TransoceanicSeaplane (Yankee Clipper Boeing 314). : AIR SPEED ALTITU DE CORRECTION 40 5 10 15 20 25 80 |00 |20 |40 |60 |80 200 220 240 260 280 300 5 |0 |5 20 25 A LTITUDE IN THOUSAND FEET follow horizontal line from indicated Airspeed to altitude. Follow oblique line back to true Airspeed. True Airspeed is always more than indicated airspeed, * .**Lá zº º Épº WA -*. 3: ë à º* = º = º* |t| à r à ---> --> E-2 à - É- à An Air Speed Altitude Correction Chart. AIR SPEED INDICATOR Pioneer Instrument company, anooklyn, New York The Internal Mechanism of a Typical Air Speed In- dicator. A Rotatable Air Speed Indicator, and the Method of Grouping Flight Instruments on the Instrument Board. Actual Size AIR “air speed—The speed of an aircraft relative to the air. Its symbol is V. *air-speed meter: & air-speed indicator – An instrument for indicating the speed of an aircraft relative to the air. It is actuated by the pressure developed in a suitable pressure nozzle or against a suitable obstruction and is graduated to give true air speed at a standard air density. The speed indi- cated by the instrument is termed the “indicated air speed." (The indicated speed is a direct measure of the lift or drag exerted on the airplane at any altitude. Stalling at all altitudes occurs for the same value of the indicated speed.) true air-speed meter—An instrument for measuring the true speed of an aircraft relative to the air. The Biram and Robinson anemometers are of this type. “air volume (airship)—See VOLUME, AIR (AIRSHIP). “air-volume displacement—See DISPLACEMENT, AIR voLUME. *airway—An air route between air traffic centers which is over terrain best suited for emergency landings, with land- ing fields at intervals equipped with aids to air navigation and a communication system for the transmission of in- formation pertinent to the operation of aircraft. The term “airway" may apply to an air route for either landplanes or seaplanes or both. 3. fairworthiness means conformity with requirements pre- scribed or deviations therefrom approved by the Assistant Secretary of Commerce for Aeronautics. *alarm, gas-cell—A device, fitted adjacent to a gas cell, which indicates or warns when a predetermined limiting pressure has been reached in the gas cell. Also called “pressure alarm." alcohol, denatured is alcohol which has been rendered unfit for beverage purposes and freed from government excise tax by the addition of other elements which are designed to accomplish the purposes mentioned above but do not contribute to the efficiency of the chemical. It is used in a solution with water as an antifreeze mixture in radia- tors. A solution of 40% denatured alcohol will protect against freezing to about 0° Fahrenheit. alignment—To adjust or put an airplane into designed form or shape. alloy—A material treated or refined with some other sub- stance to form a new material with different properties. *altigraph—An altimeter equipped with a recording mechan- ism. Present instruments are of the aneroid type. The chart, driven by clockwork, is usually graduated in feet or meters in accordance with some empirical or arbitrary pressure-temperature-altitude formula. In other words, it is a barograph whose scale is designed to read heights. *altimeter—An instrument for measuring or indicating the elevation of an aircraft above a given datum plane. altimeter—An adaptation of the aneroid barometer gradu- ated to indicate units of height above sea level or the ALT ground (any reference line). *altimeter, aneroid—An altimeter, the indications of which depend on the deflection of a pressure-sensitive element. The graduations of the dial correspond to an empirical or arbitrary pressure-temperature-altitude formula. *altimeter, electrical-capacity—An altimeter, the indications of which depend on the variation of an electrical capacity with distance from the earth's surface. *altimeter, engine—An altimeter for indicating the altitude corresponding to the pressure produced in the intake manifold of a supercharged engine. altimeter lag—See LAG, ALTIMETER. *altimeter, optical—An altimeter, the indications of which depend on the manipulation of a suitable optical system. *altimeter, sound-ranging—An altimeter, the indications of which depend on the measurement of the time required for a sound wave to travel from the aircraft to the earth and back. altitude (astronomical) is the angular distance of the sun or any heavenly body above the horizon. altitude control—Partial vacuum or auxiliary air port meth- ods of carburetor control designed to adjust the fuel vapor mixture for various altitudes. Since mixture ratios are on a weight basis it is necessary to use an altitude control for efficient operation above 10,000 feet, because the lower density of the air causes the mixture to become increas- ingly rich. altitude, flight is the vertical distance from sea level or any given reference line to an aircraft. aluminum alloys are used extensively in engine construction for crankcases, pistons, rocker arms, etc. With improve- ments made in the method of welding, aluminum is being iargely used in the construction of fuel tanks. ammeter is an electrical device or instrument used to meas- ure the flow of current in a circuit. It is always connected in a series on the positive side of a circuit between the source of current supply and the power using unit. ampere—The unit of electrical current flow. The product of volts and amperes equals watts (the unit of electrical power). *amphibian—An airplane designed to rise from and alight on either land or water. anchor men—That part of the launching crew holding the tail of a glider while the shock cord is being stretched. *anchor, sea—An open fabric bag carried on an aircraft and arranged to offer considerable resistance when towed mouth-first through the water. Tripping or collapsing devices may be incorporated in it. Also called "drogue." *anchorage, snatch-block—An anchorage set in the ground for a snatch block used with a yaw line from a mooring mast. The anchorages may be of concrete or timber and are usually arranged at equal intervals around the circum- ference of a circle whose center is the mast; may also be applied to any anchorage for a snatch block used in haul- SN Nº | ALTIMETER Pioneer INSTRUMENT CowParly, arooklyn, New York The Internal Mechanism of a Typical Altimeter. A Two Revolution Sensitive Altimeter with a Baro- metric Scale. TWO REVOLUTIONS ‘’Iſojuſ VUſ （2Joqsewu awoqJOu oſnovy3ų L ,^/o/_Zć224/ →/º A，22/23/27/Z” EZAZZ Zvº2º^ C7 5727/?S?:57ZW S/. //S?/////////247 -3/2=77&øy „... • >>&Z_4..Zº zo 7742427 G#-º| _） , !- ANE ing down an airship or kite balloon. *anemometer—An instrument for indicating or measuring the speed of an air stream. *aneroid altimeter—See ALTIMETER, ANEROID. angle is a structural section composed of two flanges or legs which are at right angles to each other. When the legs are not of the same dimension the angle is usually so placed in a structure that the greatest load (bending) comes on the leg of largest dimension. In such cases, the larger dimension really acts as a web and the smaller dimension as a flange. angle, acute—An angle less than 90°. - *angle, aileron—The angular displacement of an aileron from its neutral position. It is positive when the trailing edge of the aileron is below the neutral position. angle, burble is the excessive angle of attack for an airfoil at which the streamline flow is disturbed to such an extent that the lift decreases rapidly, permitting a stall. *angle, critical—An angle of attack at which the flow about an airfoil changes abruptly with corresponding abrupt changes in the lift and drag. *angle, downwash—The angle through which an air stream is deflected by any lifting surface of an airplane. It is measured in a plane parallel to the plane of symmetry and is denoted by the symbol e. *angle, drift—The horizontal angle between the longitudinal axis of an aircraft and its path relative to the ground. *angle, effective helix—The angle of the helix described by a particular point on a propeller blade as the airplane moves forward through air otherwise undisturbed. It is equal to the angle whose tangent is the ratio of the veloc- ity of flight to the product of the four quantities: 2+,+ (the distance from the axis to the point in question) and n (the number of revolutions per second), i.e.: q} = tan-( V 27trn *angle, elevator—The angular displacement of the elevator from its neutral position. It is positive when the trailing edge of the elevator is below the neutral position. angle, gliding—The angle between the horizontal and the downward path along which an airplane descends at normal flying speed, but not under power. *angle, landing—The acute angle between the line of thrust of an airplane and the horizontal when the airplane is resting on level ground in its natural position. Also called “ground angle." - *angle, longitudinal dihedral—The difference in angle of wing setting and of stabilizer setting. (This angle is posi- tive when the angle of stabilizer setting, referred to the thrust line, is less than the angle of wing setting.) “angle, minimum gliding—The acute angle between the hori- zontal and the most nearly horizontal path along which an airplane can descend steadily in still air when the pro- ANG peller is giving no thrust. angle, obtuse is an angle greater than 90°. “angle of attack—The acute angle between the chord of an airfoil and its direction of motion relative to the air. (This definition may be extended to other bodies than airfoils.) Its symbol is oc. “angle of incidence of wing—See ANGLE OF WING SETTING. angle of incidence, aerodynamic—The angle at which the neutral lift line of an airfoil attacks the air relative to the direction of motion. This means that an airfoil may gen- erate a large amount of lift at zero angle of attack, due to the aerodynamic angle of incidence resulting from the cambered design of the wing. angle of incidence, best climbing—That angle of incidence at which an airplane ascends the quickest. angle of incidence, maximum—The greatest angle of inci- dence at which horizontal flight can be maintained. angle of incidence, minimum—The smallest angle of inci- dence at which horizontal flight can be maintained. angle of incidence, optimum — That angle of incidence at which the lift-drag ratio is the highest. angle of incidence, riggers—The angle that the chord of a surface makes with a line parallel to the axis of the pro- peller. “angle of pitch—The acute angle between two planes defined as follows: One plane includes the lateral axis of the air- craft and the direction of the relative wind; the other plane includes the lateral axis and the longitudinal axis. (In normal flight the angle of pitch is, then, the angle between the longitudinal axis and the direction of the relative wind.) This angle is denoted by 6 and is positive when the nose of the aircraft has risen. “angle of roll, or angle of bank—The acute angle through which an aircraft must be rotated about its longitudinal axis in order to bring its lateral axis into a horizontal plane. This angle is denoted by p and is positive when the left wing is higher than the right. “angle of stabilizer setting—The acute angle between the line of thrust of an airplane and the chord of the stabilizer. “angle of wing setting—The acute angle between the plane of wing chord and the line of thrust. It may differ for each wing. *angle of yaw—The acute angle between the direction of the relative wind and the plane of symmetry of an aircraft. This angle is denoted by W and is positive when the air- craft has turned to the right. *angle, propeller-blade—The acute angle between the chord of a propeller section and a plane perpendicular to the axis of rotation of the propeller. Usually called “blade angle." "angle, rudder—The acute angle between the rudder and the plane of symmetry of the aircraft. It is positive when the trailing edge has moved to the left with reference to the normal position of the pilot. * T ~~~~ * ~~~~~~ — , 2-—jº-s-s- Tº -> * iss TT. Tºri----- —E::= —---- ~~-e- ======== ------ Is I —- -º zo” Azaze 2- azzzce: Group Illustration showing the Flow of Air about an Airfoil for various Angles of Attack. Lateral Dihedral in Low Winged Monoplanes (Boe- ing Stratoliner and Douglas DST). Žezsz. Zaz :*:::::::::::::: -: == sº e - - - r - -- f 22c \| 2 ^ N / / '%ZA 2. 5) 2^ \ - 2^ Z Azzzzzzº&/7&ZA, Že ºzze /a/- \ Zoº &azazzazz) A444; 2/* A 77/7c4 (ºr) / 5 AP Pºzz//7242 2/raºzz ////~/ 2&z=a^25 Z/22/y 7742: Ayz ZZ72/CAE //Y 94%//ø/ 77% A*/2427 /2ZAZarzº.5 Z///5 A//a Az/7/YA: ax Azazzy 5 2/− 7//a Aza tº 7-225 . ///z AzozzA 2A zo'czzzzzzcz- /5 ca/Y 57/7/Y7. The Distinction between the Angle of Incidence and the Angle of Attack. ANG “angle, wing-dihedral or dihedral—The acute angle between the transverse reference line in the wing surface and the lateral axis of the airplane projected on a plane perpen- dicular to the longitudinal axis. The dihedral angle is positive when the upper obtuse angle for the two wings is less than 180°. angle, lateral dihedral—Lateral dihedral angle is the angle included between the planes of airplane lifting surfaces when they are inclined upward or downward towards the wing tips. A dihedral angle is an angle greater than 90° and less than 180°. If the wing tips are inclined down- ward, the dihedral angle is said to be negative. ° angle, zero-lift—The angle of attack of an airfoil when its lift is zero. annealing—Heat treating of metal designed to refine the grain and toughen the metal. It is usually accomplished by long continued heating or baking and slow cooling. “antiflutter wire—See WIRE (AIRSHIP), ANTIFLUTTER. antifreeze mixtures are mixtures of chemicals and water (usually) which are used in radiator solutions to secure the benefit of lower freezing points. Also in compass bowls. “apparatus, water-recovery—Apparatus carried on an air- ship for condensing and recovering the water contained in the exhaust gases of internal combustion engines in order to avoid the necessity of valving gas as the fuel is consumed. *appendix—The tube, usually located at the bottom of a bal- loon, primarily used for inflation and deflation. In the case of a free balloon it may also serve as an automatic- discharge opening. Originally applied to free balloons only. Should be restricted to the various types of balloons and not applied to airships. *appendix manhole—See MANHOLE, APPENDIX. *apron—A hard surface area of considerable extent immedi- ately in froß of the entrance of a hangar or aircraft shelter which is used for the handling of aircraft or for repair in clear weather. Archimedes' Principle—When a solid body is immersed in a liquid, a buoyant effort equal to the weight of the liquid displaced acts upward and opposes the action of gravity. argon is a small constituent of the atmosphere. It has the greatest density of any gas in the composition of the atmosphere. armature refers to the rotating elements in motors, magnetos . generators and also to the cores of electro-magnetic COIS. articulated connecting rod — See CONNECTING ROD, ARTICU- LATED. artificial horizon—See HORIZON, ARTIFICIAL. ash is springy, strong in tension, hard and very tough. Its weight is greater than spruce but, when properly ferruled, C3Il º: the same weight be made stronger than any other WOOO!. 4. ASP *aspect ratio—The ratio of span to mean chord of an airfoil; i. e., the ratio of the square of the maximum span to the total area of an airfoil. *aspect ratio of propeller blade—Half the ratio of propeller diameter to maximum blade width. astronomical day commences at noon of the civil day of same date, and consists of one period divided into twenty- four hours reckoned from noon one day to noon the next day. atmosphere—The gaseous envelope surrounding the earth. atmospheric pressure—The pressure exerted by the weight of the atmosphere. The pressure on one square foot of the earth's surface at sea level is approximately 21 17 pounds. This figure divided by 144 square inches gives the pres- sure of 14.7 pounds per square inch. *attitude—The position of an aircraft as determined by the inclination of its axes to some frame of reference. If not otherwise specified, this frame of reference is fixed to the earth. attraction of magnetic fields—See MAGNETIC FIELDS, ATTRAC- TION AND REPULSION OF. Aurora Australsis—The lights in the southern hemisphere called “southern lights." Aurora Borealis—The lights in the northern hemisphere called “northern lights." auto-gyro–A heavier-than-air craft whose angles of ascent and descent are greatly increased by freely rotating air- foils (like a large propeller with a vertical axis) placed approximately in a horizontal plane. These freely rotating airfoils are not power driven, although the auto-gyro has a conventional power plant for forward speed. *automatic valve—See VALVE, AUTOMATIC. *aviation—The art of operating heavier-than-air craft. aviator—The pilot of an airplane. avigation—The guidance of craft through the air in accord with previous calculations. "axes of an aircraft—Three fixed lines of reference, usually centroidal and mutually perpendicular. The longitudinal axis in the plane of symmetry, usually parallel to the axis of the propeller, is called the longitudinal axis; the axis perpendicular to this in the plane of symmetry is called the normal axis; and the third axis perpendicular to the other two is called the lateral axis. In mathematical dis- cussions, the first of these axes, drawn from front to rear, is called the X axis; the second, drawn upward, the Z axis; and the third, running from right to left, the Y axis. axes of an aircraft—Three fixed reference lines, usually in- tersecting at a common point, and each one perpendicular to the other two. axis—A reference line about which there is rotating move- ment. The axis of the earth is the diameter or line joining the North and South Poles. Also, any line about which any orientation or plan is arranged or designed. axis, lateral—The athwartship axis in a horizontal plane .. A/wg Æease/52.5&/ºz: Asa'ara 7 x2 *ze=32- & The Aspect Ratio Determination for a Modern Air- plane (Fleet Trainer). / _= -——----- A y––– *-*--------- - - § ſ S A.272.2 AZAzoes <5457 a 7" aw J. sº ->2/4//7 //kaze 2/F Zavºzzer, ce: º ===z72-7xe–Zºexasz Zave * * ~. * - * * * J77&z/ºr 22,722, 2a, Zzzaxes as zozzzzzzzz zazez; Z Aº X/S. Pºrcaſſº occº.25 oz X &/5 w/7// gozz7/ø/y Ayeo. 7 y AZX/5. Cºyzsz 2/~ &ea rzz.” f * : * * The Three Axes of an Airplane (Curtiss Wright Air- liner). Z, !---Yeezzºz. zººs * - 40%/7//D///// Aſ X/S x 7º4452 w/zesÆæØeae/or \|_èºxszaesºego_ś„ “„ “À7：57， ſezºnae?# Ț、。a^2.^~ AŹZººaec coveaerº/2------- « æ |_2^ （|）|·AF44F vay7ºº. w ^ ）‘,^ |N. |` s .· …~ | &lºcve azoezi ，*A.}� … -|---Žēøøre%2 |••T! 7z7es_ . Q.|•ę----…»|----V----ſae• -（（）<--•1–– §| Wežisr zz^*�wŹ№， ;\, Q |•|||;\ |• •*|„--~~~~***�\ /&øpezzee éoss|}|;ſºwº – — ·Na:4% eesrae \, •}~~~~“; ^\ :_><！”G€??& 4&24&s/^& \ |r•\,^J_~~~//^«?/ E os szave/- zzz.ee ->ærrwawą • • -№Ī|-^ —&º%/Zaer sºwººk” 4-Azayºzavę~~44&-2... ：~//&SeòA?&ÆAºstZ2/yae? /////%: A Typical Biplane (Grumman Fighter). BON boil on the Centigrade or Fahrenheit scales. *bonnet—See HooD, VALVE. booster magneto-An auxiliary magneto used for the pro- duction of a strong spark for starting purposes. Booster magnetos are geared up to such an extent that sixty to one hundred revolutions of hand turning are sufficient to create a very strong spark. The booster current is con- nected to a trailing segment in the service magneto dis- tributor in such a way that the booster current can jump a small air gap to the nearest service electrode. The trail- ing segment timing feature insures that the spark can only occur after top center. bore usually refers to the size of a cylindrical hole in a part. boring mill is a machine designed to bore holes in parts by means of a rotating bed to which the work is fastened. The tool advances through the hole to the required depth. bottom dead center—The position of the piston when nearest the crankshaft—extreme position at bottom of cylinder. Bourdon Tube—A tube whose characteristic is to straighten itself out when pressure is applied internally. Bourdon tubes are used in pressure and temperature indicating instruments. *bow-cap—See CAP, Bow. *bow-heavy—The condition of an airship which, when at rest in still air, trims with its axis inclined down by the bow. The term “bow-heavy" is preferred to “nose- heavy" in describing airships. *bow-steadying line—See LINE, YAw. *bow stiffener—See STIFFENER, BOw. Boyle's Law (Law of Perfect Gases)—“The volume of a given mass of gas, varies inversely as the pressure, pro- vided the temperature remains constant.” *box girder—See GIRDER, Box. box rib—See RIB, Box. *brake mean effective pressure—The net unit pressure which, if applied during the power strokes to the pistons of an engine having no mechanical losses, would produce the given brake horsepower at the stated speed. brakes, air—See AIR BRAKES. brazing—A process of sticking metal parts together with melted brass or hard solder (copper and zinc alloy). breaker, circuit—See CIRCUIT BREAKER. "breathing—The passage of air into or out of an aerostat, due to the changing of its volume. “breathing stresses—See STRESSEs, BREATHING. Brinnell Test—A method used to test the hardness of metals. The hardness number equals the total static pressure divided by the curved area of impression made by press- ing a hardened ball into the surface of the material tested. “bridle—A sling of cordage or wire which has its ends fixed at two different points, to the bight of which a single line may be attached, either movable or fixed, thus distributing the pull of the single line to two points or more in the case of a multiple bridle. This term is also used to refer to a towing or mooring line having two legs and intended to BRI reduce yawing when towing or mooring. British Thermal Unit—The heat required to raise the tem- perature of one pound of water one degree Fahrenheit. Symbol is B.T.U. B.T.UI. = 778 foot pounds. This factor is called the me- chanical equivalent of heat. Bronze is harder than Babbitt metal, but very much softer than case hardened steel piston pins, and is generally used for piston pin bearings. Due to the rapid reversal of piston travel direction the piston pin bearing is sub- jected to considerable shock, and the additional hardness of bronze is an advantage. The principal constituents of bronze are copper and tin, although this alloy may be modified with small percentages of other metals. “building cradle—See CRADLE, BUILDING. bulkheads are lateral partitions of an inclosed fuselage. Bulkheads are used particularly in soaring and mono- coque fuselage construction. “bullseye—A circular thimble. *bºroyancy—The upward air force on an aerostat which is derived from aerostatic conditions. It is equal to the weight of the air displaced. *buoyancy, center of (aerostat)—The center of gravity of the volume of the contained gas. burble angle—See ANGLE, BURBLE. butterfly valve is any valve similar in design to the damper in a stove pipe, i.e., a valve which appears to have a wing on each side of the axis. butterfly valve—See valve, BUTTERFLY. Buys Ballot's Law—"If you stand with your back to the wind, the region of low pressure will be on the left hand in the northern hemisphere and on the right hand in the southern hemisphere.” *cabane—A framework for supporting the wings at the fuselage; also applied to the system of trussing used to support overhang in a wing. cable—One-tenth of a nautical mile (608 feet). “cable, axial—The axial member (usually steel wire cable) sometimes fitted in a rigid airship. It is attached to the central fitting of the radial or diametral wires of each main transverse and to the hull structure at bow and stern. Its purpose is to provide support for the radial or diametral wires in an axial direction and thus assist them to sustain the load which might be caused by un- equal pressure in adjacent cells or by the airship being pitched to a large angle. calibrate means to mark off the correct graduations on in- struments or scales. calorie—The heat required to raise the temperature of one gram of water one degree Centigrade. calorimeter—An apparatus for measuring the amount of heat contained in bodies. cam—An eccentric surface used to impart variable motion to the valve mechanism of engines. cam engine—See ENGINE, CAM. CAM cam follower—An engine part which rides on the contour surface of a cam and to which motion is imparted by the cam. The cam follower usually consists of a hard- ened steel roller and pivoted arm (for oscillating motion) or a steel spindle which reciprocates in a cam follower guide. The latter type is most generally used. cam follower guide—An engine part which guides the mo- tion of the cam follower. cam lobe—See LOBE, CAM. “camber—The rise in the curve of an airfoil section from its chord, usually expressed as the ratio of the departure of the curve from the chord to the length of the chbra. “Up- per camber" refers to the upper surface of an airfoil and "lower camber" to the lower surface; “mean camber" is the mean of these two. camshaft speed—% crankshaft speed, divided by the num- ber of lobes on the cam for four cycle engines. For two cycle engines camshaft speed equals crankshaft speed divided by the number of cam lobes. candle-power is the light giving power of a lumiQous source. A foot-candle is the amount of light given by a standard candle on one square foot of area at a distance of one foot. A photometer is used to determine candle- power by setting a standard candle one foot from one side of a piece of paper and moving the light to be meas- ured away from the paper on the other side until the in- tensity of light is the same on both sides of the paper. Then, the candle-power of the light equals the square of its distance from the paper. cantilever in word definition sense means a projecting arm. When a bridge is built from two sides of a gorge to be joined at the center it is said to be a full cantilever bridge, because each part of the arch carries its own weight and does not depend upon the arch itself for sup- port. When the projections toward the center of a bridge span are balanced on the opposite side (shore side) of the pier head by similar projections the bridge is said to be of semi-cantilever design. Cantilever wing design means that the entire structural strength of a wing is within the wing itself, requiring no outside bracing. When monoplane wings are braced with struts they are said to be of semi-cantilever design. However, all air- foil projections which extend beyond the last point of bracing are, in effect, cantilever projections. *capacity—The volume of the gas-containing portion of an aeroStat. *capacity, nominal gas—The volume of the envelope of gas cells of an aerostat under certain conditions of pressure and inflation which have been defined. It is rarely the same as the true full volume. This is usually very diffi- cult to determine accurately, especially in the case of rigid airships. Sometimes called “volume." * cap, bow—(1) A cap of metal or fabric used to reinforce the extreme forward ends of the bow stiffeners of a non- rigid or semirigid airship. (2) The conical or cap-shaped CAP structure at the extreme bow of a rigid airship to which the longitudinal girders are attached and which sup- ports the bow mooring spindle. “cap, nose—See CAP, BOW, which is to be preferred. cap strip is the flat strip along the contour of a wing rib. It acts as a flange to the thinner web (loom) of the rib. "captive balloon—See BALLOON, CAPTIVE. ‘car—That portion of an airship which is intended to carry power unit or units, personnel, cargo, or equipment. It may be suspended from the buoyant portion, or it may be built close up against it. It is not to be applied to parts of the keel of a rigid or semirigid airship which have been fitted for the purposes mentioned. “car, control—The car of an airship in which controls are centralized and from which it is operated. carbon residue is that part of the oil or gasoline which re- mains in the form of a carbon deposit on the cylinder after the more volatile parts of the gaseous mixture have been consumed. Carbon residue is, therefore a result of incomplete combustion. carburetor—A mechanical device for mixing liquid fuel and air in the proper proportions to form a combustible mix- ture. Carburetors are designed to mix air and liquid fuel on a weight ratio basis. carburetor float—See FLOAT, CARBURETOR. * carrier, fin—A frame to which the inboard edge of the fin of a non-rigid or semirigid airship is attached, so as to prevent the edge of the fin from sinking into the en- veiope. * car, side—See CAR, WING. cartographer is one who constructs maps and charts. *car wing—A car suspended off the center line of an air- ship. It is also called “side car." case hardening—A process of hardening the outer crust or layer of metal parts. This process creates a hard wear- ing surface without materially reducing the strength or toughness of the part, because the carbonizing is prac- tically limited to a few thousandths depth at the sur- face. A very small amount of carbonizing penetrates the interior of the part. catapult—An arrangement for launching airplanes from ships and barges through imparting initial velocity (fly- ing speed) to the aircraft by means of the rapid acceler- ation of a small car on which the aircraft is mounted. catapulting—A method of launching a glider by hooking elastic cord onto the prow of the glider and stretching out ahead of it until the elastic is taut enough to project the glider into the air when the mooring is released. * catenary—A line or length of cordage which is secured to or in a piece of fabric in the form of a catenary curve or a series of such curves. cavitation, propeller—The tendency of a propeller to pro- duce a rarified area ahead of and in the sphere of pro- peller rotation. cedar is sometimes used for fuselage covering. 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D. = 22 a Fay722 24 Aze 5.54/42/E 33% of cA/o/20 º * T | § /*, * ZoºZA= 2^* a 77*& A.- Z2. = // a Żay7&a 2A Aa A-552,22– 27%22 caceo Group Illustration of Airfoils showing the Distribution of Pressure for various Angles of Attack. CEI uniform and is easily worked. Fuselages, particularly of the monocoque design, are sometimes veneered layers of wood with the grains crossing for added strength. Tulip wood, basswood, cedar, alder and mahogany are all used in veneer covering work. * ceiling: absolute—The maximum height above sea level at which a given airplane would be able to maintain horizontal flight, assuming standard air conditions. service—The height above sea level, assuming standard air conditions, at which a given airplane ceases to be able to rise at a rate higher than a small specified one (100 feet per minute in the United States and Eng- land). This specified rate may be different in different countries. * ceiling, static—The altitude in standard atmosphere, at which an aerostat is in static equilibrium after removal of all dischargeable weights. celestial—Pertaining to heavenly bodies. celestial equator (equinoctical) is the great circle formed by extending the plane of the earth's equator until it in- tersects the celestial sphere. celestial sphere—An imaginary hollow globe surrounding the earth and having the same center as the earth. The north and south poles and the equator of the celestial sphere are projections of the north and south poles and the equator of the earth upon the celestial sphere, i.e., the north pole of the celestial sphere is vertically over the north pole of the earth, the south celestial pole is vertically over the south pole of the earth, and each point on the celestial equator is vertically over the cor- responding point of the earth's equator. See DELINEATION and RIGHT ASCENSION. *cell, gas—One of the gas-containing units fitted in a rigid airship. Sometimes called “gas bag." center line of pressure—A line running from wing tip to wing tip, through which all the air forces acting on the surface may be said to act, or about which they may be said to balance. . center line of pressure, resultant—A lateral line of pressure, the position of which is the resultant of the lines of pres- sure of two or more surfaces. “center of buoyancy—See BUOYANCY, CENTER OF (AEROSTAT). center of gravity—The center of weight or the point in an object about which the weight is balanced. “center of pressure coefficient—The ratio of the distance of the center of pressure from the leading edge to the chord length. * center of pressure of an airfoil section—The point in the chord of an airfoil section, prolonged if necessary, which is at the intersection of the chord and the line of action of the resultant air force. Its abbreviation is C. P. Centigrade Scale—The temperature scale on which water freezes at 0° and boils at 100°. centimeter equals .39 inches. CEN central runner is a single skid below the fuselage of a glider which acts as the landing gear. centrifugal force—The force which urges any body mov- ing in a curved path away from the center of the curve. centripetal force is the force which acts in an opposite di- rection to resist centrifugal force. *chafing patch—See PATCH, CHAFING. * channel patch—See PATCH, CHANNEL. chamfer means to bevel a sharp edge. channel section is a structural section consisting of a web for depth and flanges on one side only (top and bot- tom). Channels are used to carry vertical loads and have very little strength if the web is placed in a hori- zontal position. Channels may be solid sections or built up from a flat plate (web) and two angles (flanges). characteristic is the number before the decimal point (de- termined by inspection) of a logarithm. characteristic curves—See CURVES, CHARACTERISTIC. Charles' Law—"When a gas receives heat at a constant volume, the pressure varies directly as the absolute tem- perature; or when a gas receives heat at a constant pres- sure, the volume varies directly as the absolute tem- perature." chart—A representation of a portion of the surface of the earth, usually showing more water than land. chart, isogonic is a chart with lines (isogonic) drawn through points of equal magnetic variation. These lines may show magnetic variations perhaps 5° apart but, with the exception of a few places in the United States where heavy deposits of magnetic ore exist, visual interpolation by inspection is generally of sufficient accuracy to deter- mine the variation of points which are between the iso- gonic lines. choke valve—See VALVE, CHOKE. *chord (of an airfoil section)—The line of a straight edge brought into contact with the lower surface of the section at two points; in the case of an airfoil having double convex camber, the straight line joining the leading and trailing edges. (These edges may be defined, for this pur- pose, as the two points in the section which are farthest apart.) The line joining the leading and trailing edges should be used also in those cases in which the lower surface is convex except for a short flat portion. The method used for determining the chord should always be explicitly stated for those sections with regard to which ambiguity seems likely to arise. *chord length—The length of the projection of the airfoil section on its chord. Its symbol is c. “chord, mean, of a combination of wings—The ratio— c1S1 + c2S2 + c2S3 + S1 + S2 + Sá –H . . . where c1, c2, ca, etc., are the mean chords of various wings and S1, S2, S3, etc., are their areas. "chord, mean of a wing—The quotient obtained by dividing E- - 2%2 -------- - - - - - - - - - T CLIMB INDICATOR Pione tº InstrumEnt company. BROoklyn, New York The Internal Mechanism of the Climb Indicator. * * P * - - ſ CLIMB Tºusand-FEEI PER Mºuré º º --~ * --~~Tº - \ ºf tº wºuw ENT cºaº Bºx ºr mºtº worn º 374-970 - - DOWN * The Climb Indicator. CHO the wing area by the extreme dimension of the wing projection at right angles to the chord. “chord wire—See WIRE (AIRSHIP), CHORD. chromium—An alloy used to give strength and hardness to steel. Refines the grain of the metal. circle (great)—A circle on the surface of the earth, having the earth's diameter as its own diameter. True merid- ians are semi-great circles. The equator is a great cir- cle. A great circle can be drawn between any two points on the surface of the globe, and the arc of this great circle is the shortest distance between the two points. circle (small)—Any circle having less than the earth's diameter as its own diameter. The parallels of latitude are small circles, with the exception of the equator. circuit breaker—A device in the primary circuit used to break or interrupt the primary circuit. civil day is divided into two periods of twelve hours each, counted from midnight to noon and from noon to mid- night. clearance—See VALVE CLEARANCE. climate——Average weather conditions over a long period of time and a relatively large area. climate is affected by latitude, altitude, mountain barriers, topography, bodies of water, ocean currents, and pre- vailing winds. climatology is the study of climatic conditions. climb indicator—An instrument operating on the differen- tial pressure principle, designed to show the rate of as- cent and descent of aircraft. * climb, rate of LSee RATE OF CLIMB. * climbing shaft—See SHAFT, CLIMBING. * cloth—Fabric delivered by the bleachery or finisher before it has been proofed, doped, or specially treated for aero- nautic use. * cloth, ground—Canvas placed beneath an aerostat for its protection during inflation and deflation. clouds—An accumulation of condensed moisture in the air which is visible. The moisture may become frozen as in cirrus clouds at high altitudes. cloud forms and definitions according to the International System of Classification: 1. Cirrus (Ci.) Detached clouds of delicate and fibrous ap- pearance, often showing a featherlike structure, generally of a whitish colour. Cirrus clouds take the most varied shapes, such as isolated tufts, thin filaments on a blue sky, threads spreading out in the form of feathers, curved filaments, ending in tufts, sometimes called Cirrus wheinus, etc.; they are sometimes arranged in parallel belts which cross a portion of the sky in a great circle, and by an effect of perspective appear to converge toward a point on the horizon, or, if suffi- ciently extended, toward the opposite point also. (Ci.- St. and Ci.-Cu., etc., are also sometimes arranged in similar bands.) Mean height: 33,000 feet. CLO 2. Cirro-stratus (Ci.-St.). A thin, whitish sheet of clouds sometimes covering the sky completely and giving it only a milky appearance (it is then called Cirro-nebula) at other times presenting, more or less distinctly, a formation like a tangled web. This sheet often pro- duces halos around the sun and moon. Mean height: 32,000 feet. 3. Cirro-cumulus (Ci.-Cu.), Mackerel Sky. Small globular masses or white flakes without shadows, or showing very slight shadows, arranged in groups and often in lines. (Small A.-Cu. may also be “Mackerel Sky."). Mean height: 27,000 feet. 4. Alto-stratus (A.-St.). A thick sheet of a grey or bluish colour, sometimes forming a compact mass of dark grey colour and fibrous structure. At other times the sheet is thin, resembling thick Ci.-St., and through it the sun or the moon may be seen dimly gleaming as through ground glass. This form exhibits all changes peculiar to Ci.-St., but from measurements its average altitude is found to be about one-half that of Ci.-St. (Nonfibrous A.-St. is often undulated or festooned.) Mean height: 20,000 feet. 5. Alto-cumulus (A.-Cu.). Largish globular masses, white or greyish, partially shaded, arranged in groups or lines, and often so closely packed that their edges appear confused. The detached masses are generally larger and more compact (resembling St.-Cu.) at the center of the group, but the thickness of the layer varies. At times the masses spread themselves out and assume the ap- pearance of small waves or thin slightly curved plates. At the margin they form into finer flakes (resembling Ci.-Cu.). They often spread themselves out in lines in one or two directions. Mean height: 15,000 feet. 6. Strato-cumulus (St.-Cu.). Large globular masses or rolls of dark clouds often covering the whole sky, especially in winter. Generally St.-Cu. presents the appearance of a grey layer irregularly broken up into masses of which the edge is often formed of smaller masses, often of wavy appearance resembling A.-Cu. Sometimes this cloud- form presents the characteristic appearance of great rolls arranged in parallel lines and pressed up against one another. In their centers these rolls are of a dark colour. Blue sky may be seen through the intervening spaces, which are of a much lighter colour. St.-Cu. clouds may be distinguished from Nb. by their globular or rolled appearance, and by the fact that they are not generally associated with rain. Mean height: 9,000 feet. 7. Cumulus (Cu.), Woolpack Clouds. Thick clouds of which the upper surface is dome-shaped and exhibits protuberances while the base is horizontal. These clouds appear to be formed by a diurnal ascensional movement which is almost always noticeable. When the cloud is opposite the sun, the surfaces facing the observer have a great- er brilliance than the margins of the protuberances. When the light falls aslant, as is usually the case, the CLO clouds throw deep shadows; when, on the contrary, the clouds are on the same side of the observer as the sun, they appear dark with bright edges. True cumu- lus has well-defined upper and lower limits, but in strong winds a broken cloud resembling cumulus is often seen in which the detached portions undergo continual change. This form may be distinguished by the name Fracto. cumulus (Fr.-Cu.). Mean height: 6,000 feet. 8. Cumulo-nimbus. (Cu.-Nb.), the Thunder Cloud; Shower Cloud. Heavy masses of cloud rising in the form of mountains, turrets, or anvils, generally surmounted by a sheet or screen of fibrous appearance (false cirrus) and having at its base a mass of cloud similar to nimbus. From the base local showers of rain or snow (occasionally of hail or soft hail) usually fall. Sometimes the upper edges assume the compact form of cumulus, and form massive peaks round which delicate "false cirrus" floats. At other times the edges themselves separate into a fringe of filaments similar to cirrus clouds. This last form is particularly common in spring showers. The front of thunderclouds of wide extent frequently presents the form of a large arc spread over a portion of a uni- formly brighter sky. Mean height: Top, 20,000 feet, base, 4,500 feet. 9. Nimbus. (Nb.), Rain Clouds. A thick layer of dark clouds without shape and with ragged edges, from which steady rain or snow usually falls. Through the open- ings in these clouds an upper layer of Ci.-St. or A.-St. may be seen almost invariably. If a layer of Nb. sep- arates up in a strong wind into shreds, or if small loose clouds are visible floating underneath a large Nb., the cloud may be described as Fractoºnimbus (Fr.-Nb.) ("Scud" of sailors). (Note that all rain clouds are not nimbus (nor Cu.-Nb.), but only those having the characteristics as defined. A.-St., St., and St.-Cu. fre- quently yield rain or snow, while precipitation occa- sionally reaches the ground from A.-Cu., Cu., and possibly others.) Mean height: 3,000 feet. 10. Stratus (St.). A whiform layer of cloud resembling a fog but not resting on the ground. When this sheet is broken up into irregular shreds in a wind, or by summits of mountains, it may be distinguished by the name Fracto-stratus (Fr.-St.). (St. may be undulated or fes- tooned, even though “uniform". Its evident low height (under 1,000 meters) distinguishes it from nonfibrous A.-St.). Mean height: 2,000 feet. cloud soaring is soaring by utilizing the up-currents near clouds. Soaring in the up-currents just below large cumulus clouds is a notable example of cloud soaring. In this connection it is to be noted that a soaring machine is continuously in a gliding attitude, and that altitude is held or increased because the whole body of air is mov- ing upward. CLO clockwise means a rotation in the direction indicated by the movement of clock hands. *cockpit—The open spaces in which the pilot and passen- gers are accommodated. When the cockpit is completely housed in it is called a cabin. coercive force—See FORCE, COERCIVE. coil (high tension)—A device used to raise the potential of low voltage circuits to the high potential necessary for jump spark ignition. col is an area of almost uniform barometric pressure be- tween two highs and two lows, the highs and lows being practically opposite to each other like partners in a bridge game. cold test is used to determine the lowest temperature at which an oil will flow. combustion—The process of burning. *compartment, control—A compartment in the control car of an airship from which all controls are operated. It may be compared to the pilot house of a ship. compass—An instrument used to determine direction by the orientation of ships or airplanes about a compass card or direction control whose reference point is North. compass course—See CourSE, COMPASS. compass error—The combined error of variation and devi- ation. The combined error is East or West, being named after the largest individual error. Example: If the vari- ation is 17 E and the deviation is 4 W, then the total compass error is 13 E. compass, earth inductor—See EARTH INDUCTOR COMPAss. *compass, induction—A compass, the indications of which depend on the current generated in a coil revolving in the earth's magnetic field. compass north—See NORTH (COMPASS). compass rose—The design of a compass card engraved on charts and maps, indicating either true or magnetic di- rections, or both. Several magnetic compass roses may appear on a map or chart, because the variation is dif- ferent for neighboring localities. Always use the rose nearest to the course being plotted. If several magnetic roses appear along an extended course, the course must be plotted in sections to account for changing variation along the course. component part or force is any one of the several forces or parts in a combination. composition of forces is the process of finding the resultant of several component forces. compression—The degree to which any gas or compressible substance is compressed by reducing the volume or avail- able space. compression ratio—The ratio of the total cubic displacement of a cylinder to the compressed volume (combustion chamber when piston is at top dead center). compression rib-See RIB, COMPRESSION. concentric means having the same or a common center. Will produce true circular motions. |Vºzves VII iſ 2-tºes: : §: : | —3oae--- | Vozams Sºi- || |--|-- ---- | /22 il Ceav/e 6 I | %2. | # § ! ZºZº. | $ 8 Wozoane [|| § AEszow | l tº 2 SY /º/, //CEM | S § | N. | || w L | – || -- &orzoan º C4-FA/Zºº & |T|| TITT TIT | : f sº | | | Relative volumes compared to stroke and combustion chamber Detail Showing Compressed Volume, Total Volume and Piston Displacement. . /7 a jr. Jo vºn al/ Tubular Section Connecting Rods Side by Side on a Single Crank Pin Serving Two Banks of a V-Type Engine. /Marszee:T C2/vazcz//vºy A3oz, A/s/orn Air, A/e/e TOT y- | i! | | * ! º | | ty Sk S t *S. 2 t | c | & | H F- Q O § | j| Alal in c/) | Joe, a n all t L I-Section Connecting Rod with Bearing Cap Bolted O In . — CON * concentration ring—See RING, conce NTRATION. condensation—The return of water vapor in the air to a solid or liquid state. condenser — A device, short circuited across the breaker points, designed to store the back pressure induced in the primary circuit of a magneto. The condenser is also necessary in battery ignition. *condenser, water-recovery—That part of the water-recov- ery apparatus which is devoted to the condensing of water in the exhaust gases. It may consist of a number of metal tubes or of a fabric box with appropriate inlets, outlets, and baffles. conductance of an electrical circuit is the reciprocal of the resistance, being the ease with which electricity may pass through a conductor. conduction—The transference of heat from one part of a body to another through the molecules or from one body to another by contact. conductors (electrical)—Materials which have the prop- erty of conducting electricity. “cone, axial—The cone-shaped fabric, fitting in the end of a gas cell of a rigid airship, which provides a gas-tight connection of the cell to the axial cable and yet permits the cell some degree of freedom in its movements. A special form of conical sleeve. *cone, danger—A pennant on the wire cable of a captive balloon to warn aircraft of its presence. Usually a hollow cone of light cloth. * cone, mooring—The grooved conical member at the ex- treme bow of an airship which engages with a hollow cone at the top of the mooring mast and provides the coupling between the airship and the mooring mast. configuration is the shape of the pattern of a group of stars in a constellation. * conical sleeve—See SLEEVE, CONICAL. connecting rod—A rod with a bearing at each end con- necting the piston pin (wrist pin) and an off-set (crank pin) on the crankshaft. connecting rod, articulated is a connecting rod which joins the piston of one cylinder to the master connecting rod of another cylinder by means of a knuckle pin bearing at a distance from the center of the master rod and crank pin bearing. constellation means a group of stars after a regular pattern which can be identified. * container, gas—See CELL, GAS, which is to be preferred. continental winds—The secondary circulation of the at- mosphere. contour lines on a map are lines drawn through points of approximately the same altitude above sea level. These lines indicate altitude above the reference line, but do not actually show it as a profile line does. * control car—See CAR, CONTROL. “control compartment—-See COMPARTMENT, CONTROL. CON * controllability—The quality in an airplane which makes it possible for the pilot to change its attitude easily and with the exertion of but little force. * control lines—See LINES, CONTROL. control, reverse—See REVERSE CONTROL. “controls—A general term applied to the means provided to enable the pilot to control the speed, direction of flight, attitude, and power of an aircraft. air controls—The means employed to operate the control surfaces of the aircraft. engine controls—The means employed to control the power output of the engines. (Control of speed may be effected by the air controls or the engine controls in- dependently, or by either in conjunction with the other.) * control stick—The vertical lever by means of which the longitudinal and lateral controls of an airplane are oper- ated. Pitching is controlled by a fore-and-aft movement of the stick, rolling by a side-to-side movement. * control surface—See SURFACE, CONTROL. convection—The transference of heat from one point to the other by circulation of the air. Rising columns of warm air is an example. convection, mechanical is the ascension of air due to its de- flection by barriers and obstacles. *cord grommet—See GROMMET. *cord netting—See NET, GAS CELL (RIGID AIRSHIP). *cord, rip—The rope running from the rip panel to the car or basket, the pulling of which tears off or rips the rip panel and causes immediate deflation. corrosion is the deterioration of exposed surfaces due to climatic conditions, immersion in water or liquids, or subjection to acids, alkalies, gases, etc. coulomb is the unit of electrical quantity, being the quan- tity of electricity which will flow in a circuit in one sec- ond under a pressure of one volt and against a re- sistance of one ohm. "counter-clockwise means a rotation opposite to the direc- tion indicated by the movement of clock hands. countersink is to remove enough material about the end of a hole so that the heads of rivets, bolts and screws may be brought down flush with the surface of an object. course (compass)—The angle measured clockwise from the compass meridian to the line joining two places. course (magnetic)—The angle measured clockwise from the magnetic meridian to the line joining two places. course (true)—The angle measured clockwise from the true meridian to a line joining two places. "cover, outer—The outside covering of the hull of a rigid airship, usually of some kind of fabric. Sometimes called the "envelope." * cover, valve—See HOOD, VALVE. *cowling—A removable covering which extends over or around the engine, and sometimes over a portion of the fuselage or nacelle as well. º Kia---z/age Æ & a 2 & &_ | Jra, eſ/ /z = % | |S. 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Jºze/Z/Zea. 2/ <2/v722.s " */a-4:42.2ay 5’ The Elevator Controls of a Conventional Airplane. &ayzzzeſze rø, Zowaazzez /ayzawa’s Azaz, sz <5747-4× Af Af * //A26.A. <2% / «2^zzazzazeze. 2 *~~~ * - * ZºoZ2/aº & -54/27 / Zaza & 22&e- AºA'72 ºr 7 ºz, The Cowl on a Douglas B-18 Army Bomber. 283 2. ºf º- 4. –3 Q 242 442 6 £2 & 62 / Z2/7 57&M/A/PE/2 /. 894. 2.4%/5 3.35.5 4.200 4.683 5345 35.738 5.4%/ 6. CO2 5.3 C3 5.2%. 4.563 3,644 2.623 /.443 .807 (424) O -/.3% –26/.5" –3, 5,55. -4.200 -4.4383 –5, 345 —5.738 AdWEAE : * Aº i 63 2 C) 40 60 AEE2 ce/Y7 2A CA/ozp 430 /4% —5.24/ -6.902. -5:303 —5.2%- –4.5%3 -36,64 -2.6323 ~/ 443 - 307 (ZZé) O 4. E. Žpzzls As & all Z|| * % º S y \ 2. Z / Lºr Co l *~ - -* * / Y|5/zz 3'x30" A/ead/z: /A.C.A. 0012 K.A. 3230 000 Wel.(?:/Sec); 68.4 Aess.(972 Araz); 20.7 Zzza /Z-52-3/ }%eze 7:57azy i Z.//4./I./2.57: V/27 7.43 Ca22&752 /22 Z/YA/ez.-AZZZ. AfEEacz- 4. O 4. Æ /Z AZA 2A 4777/7ce, arCZAze=45) The Characteristic Curves for the N.A.C. A. V. D.T. 00 || 2 Airfoil. /4, 20 24 23 j2 2.0 .42 /.8 .3ſo /ſo .32 /.4 26 S. § { 123, 24 S \!. G * N. Ü R Lo Úzo S. \", \ § Š .8VT **s W .6" ſº *N .4 .08 .2 .04 o C cezae Aºy *** **s-, n in nº ceze A/e/ | } \ --~~~~< * º F is º f * * -R- Jº-li- 71° º , -, E={ PR=== Rºº-ºº: #. †† \ . * vozzeavaz. \ .” Ceawayz Aºaz.5 / Jac//o/y A7–45 The Nomenclature of a Crankshaft. This Crankshaft is Typical for an In-line Six Cylinder Engine. Zezesz &eazzavg. Zºe e^2/azzz' Azoo/7 easa'ezay? Aº -/oczeavaz- A Z Zazzazz &ary” / * ,” _- ~~ _ar Cozzyzzéz//e/42//7.5 . The Nomenclature for a Single Throw 360° Radial Crankshaft. CRA crabbing is the heading of an aircraft up into the wind in order to preserve a straight cross-wind track between two points. * cradle: building—A support provided for the frame of a rigid airship or the keel of a semi-rigid airship during con- struction. docking—A support for the car of an airship while it is being inflated in the shed. Mostly used with rigid air- ships. crankcase—The cast basic section of an engine in which the crankshaft bearings, thrust bearings and various ac- cessories and drives are mounted and to which the cylin- ders are fastened. crankshaft—The main shaft on an engine to which rotary motion is imparted by the piston through a connecting rod and off-set throw on the shaft. * crew, ground—See CREW, LANDING. * crew, landing—A detail of men necessary for the landing and handling of an airship on the ground. A “ground crew." crew, launching—See LAUNCHING CREW. * critical angle—See ANGLE, CRITICAL. * critical speed—See SPEED, CRITICAL. “cross-country flight—See FLIGHT, CROSS-COUNTRY. cross ties—The main structural members laterally across the top and bottom of the fuselage. cross-wind—A wind blowing from right angles to the direc- tion of flight or take-off. Variations from a 90° angle are said to be on the bow or quarter. * cross-wind force—See FORCE, CROSS-WIND. “crow's-foot—A system of diverging short ropes for dis- tributing the pull of a single rope. An arrangement in which the strands of a cord are opened out so that they can be effectively cemented to a fabric surface. * cruciform girder—See GIRDER, CRUCIFORM. cube root of a number is that number which, when multi- plied by itself twice, will equal the number. Thus, the cube root of 8 is 2, because 2 × 2 × 2 = 8. current, electric is electricity in motion in conductors. curves (characteristic) are plotted curves or graphs which show: Lift coefficients for various angles of attack, Drag coefficients for various angles of attack. Lift-Drag ratios for various angles of attack, Center of Pressure for various angles of attack. curve diagrams are the representation of relative values as shown by distances drawn to a predetermined scale. Making curve diagrams is called "plotting." The dia- grams are also called "graphs.” Instruments whose names end with the suffix graph are usually adapted to the printing of permanent records in the form of curve diagrams. Even though a graphical record appears as a straight line, it is still called a curve diagram, because a straight line is really a curve of zero curvature. CYC cycle—One phase of a 2 or 4 stroke cycle, i. e., the intake, compression, power or exhaust stroke—the full series of strokes is called a complete "cycle." cylinder—A hollow cylindrical section designed to permit reciprocating motion of a piston placed therein. "damping factor—The factor e—” in the equation of damped harmonic motion. s = Ae –” sin pt. *danger cone—See CONE, DANGER. datum line—An assumed level to which altitudes are re- ferred. Sea level, or at Reno, Nevada, an imaginary line of 4,000 ft. altitude, may be assumed. dead center is the situation that exists when the center line of the connecting rod is in line with the centers of the crank pin and the crankshaft. This may occur at the top or bottom of the stroke. * dead load—See WEIGHT, EMPTY, which is to be preferred. dead reckoning is the method of plotting courses, distances and positions on maps and charts. Finding the place of a craft without celestial observations from a record of the courses flown and the distance made on each course. * decalage—The acute angle between the wing chords of a tri-plane or multiplane. declination (of a heavenly body)—The arc of the merid- ian (celestial) intercepted between the equator and the body. declination (parallels of) are small circles of the celestial sphere whose planes are parallel to the equator. They are analogous to parallels of latitude on the earth. * deflation—The act of removing gas and air from an aerostat. * deflation sleeve—See SLEEVE, DEFLATION. deformation is the amount of alteration in form of a body produced by a stress. It may be tensile, compressive, bending, or shearing deformation, depending upon the type of stress causing it. degree—1/360 of a circle. For smaller divisions there are sixty minutes (60’) in one degree and sixty seconds (60”) in one minute. degree of latitude is always 60 nautical miles. degree of longitude at 30° latitude—52 miles. degree of longitude at equator—60 miles. One minute of longitude at the equator equals one nautical mile. degree of longitude at 60° latitude—30 miles. denominator is the figure under the bar in a fraction. density—The relative weight per unit volume of a substance compared to the weight of water for the same unit volume, the density of water being taken as one. density, magnetic—See MAGNETIC DENSITY. departure—The distance measured due East or West from the meridian of the starting point to the meridian of the present position. depression is another name for an area of low barometric pressure. -- deviation—The angle measured East or West from the mag- netic meridian to the compass meridian. Corneression of Freš h Gals. 77-air's Fer Porf: Air Infa ke Fresh Gas Erferin . Cra n kcase Throw . Aoformalfic Wal/ve. Power Sf rok e. Afzpains for ofº Hof Gases. Cornpressed in Crain kcalse. Aresh Gas es. |: Asafer-ing Cy/inder A Peo rºt Cra rak C a se. Three Views of Three Port Two-Stroke Cycle Design. ; §§ & * g. # . º Afrno /4.7°sy. /ry. & arº º A ſº ; lo - tº ~ * c p §§ Aress ure in Ibs. 36. in. 5: s § 3 ; ; ; ; - Sº º Sº a zºº ºx º' º ; : .# ºf ºzer Y * /š º * * = zº .. 2 § P S. 3. º Čn * s & 3 O ſº [. § {, } * gº º § S ; sº. } : ſ: J (s 5 X) & * º ſ S ºn o' | gº S. J E; º So {b =: ſ: Q & E; : * Y =3; ; º ! 3 ! ! ſ Fºr zºvº-º-; >< ºf . * * * *.*.*., Sº ...?' ** 3. . . '. § { } . . ; A tº sº tº Ž ‘. . 2 i t | º ‘. . ºftºp º *: ... •,•. * * * * :E * * * ...~x.S.: £º Pa ºr-R Sº º º º #Hº *—x -º ޺ | g º º: Eºº-s º-> Sºº! * § º ºf zººs ſº º sº b * ~ * * - ºr |SS ſ | Gº N º - - sº 23Sº - º º zº | | | § | - 3. º & ** * S., º w; 50 S S 40 \º ** †- Qu © * § 30 X (2 § 2 A- * - - © 26S Q- £gnifion $ºe JOO A* Rºszor, Exhaust < Tºmºmº- & °o º r Tr >-g W Ö Q tº w-r G § 3 & § $777& 3 's 's gº|3 & E. * * * *s * * Qj kCorn 6 usfron S?"ro Áe CA, a rºw ber / Uºn if 4 Urm if 5 Corr.pression Arari o J fe /. Cylinder Layout and Indicator Diagram for Four- Stroke Cycle Engine. Indicator Diagram is Plotted to Show Cylinder Pressures at Various Stages of the Stroke. INTAKE WALWE OPEN IV- Mixture of air and gasoline enters cylinder from car- buretor. BOTH WALWES CLOSED Combustion heat in- creases the cylinder pressure forcing pis- ton downward. BOTH WALWES CLOSED BOTH WALWES CLOSED Mixture is com- pressed into small- er volume by pis- ton moving upward. An electric spark ignites the com- pressed mixture causing it to ex- plode. EXHAUST WALWE OPEN Momentum carries pis- ton upward which push- es burnt gases out through the exhaust valve. Analysis of Action in a Four-Stroke Cycle Design. -------|- L. T-------- T- Head L- Hea. e. : 3:? Hemispherſ ca/ =: ce in Busri on E: Chalmber # | # | § ºzºº 2% % Over head. oº::flººd- Val / ves ºf – =- genews?ion chairnēer_ 2. S P/alf Hea. d. Porne Hea. d. Cylinder Arrangement and Cylinder Head Types. DEW dew—Condensed water vapor deposited on solid bodies due to the fact that the bodies are colder than the surrounding alſ. dewpoint—The temperature below which air must give up some of its water vapor as its capacity for moisture dimin- ishes. diagrams, curve—See CURVE DIAGRAMS. diamagnetic substances are substances which are feebly re- pelled by magnetism. "diametral wire—See WIRE (AIRSHIP), DIAMETRAL. *diaphragm, ballonet—The fabric partition between the gas and air compartments of the envelope of a non-rigid or semirigid airship or kite balloon. diaphragm, as applied to instruments, means a pressure sensitive element of thin rubber or metal, or the diaphragm may be a light metal cell from which the air has been exhausted. Different pressures on opposite sides of a diaphragm, or without and within a cell, will govern the registering hand on a dial. diathermanous is a condition of a substance which permits the free passage of heat rays. *. Diesel engine—See ENGINE, DIESEL. *dihedral angle—See ANGLE, WING-DIHEDRAL. dimpled or recessed type of riveted joint is usually used on thin sheets of metal to remove shearing stress and also to give a flush surface, since thin sheets cannot be counter- sunk. At the proposed point of riveting the two sheets are coincidentally recessed with a punch and die, and the recess acts as a countersink for the rivet head. The recess takes the shearing stress. dip (of the horizon) means an increase in altitude caused by the elevation of the eye above sea or ground level. directional radio—Used to plot position by means of radio bearings. direction of magnetic lines of force—See MAGNETIC LINES of FORCE (DIRECTION). *dirigible—That can be directed; steerable; as a dirigible balloon. Its use as a noun to indicate an airship is im- proper. “dischargeable weight—See WEIGHT, DISCHARGEABLE. discharge nozzle (carburetor) is the nozzle through which the liquid fuel is discharged into the Venturi air stream. “displacement—The mass of air displaced by the gas used for inflation. It may be expressed as a weight or volume. In the latter case it is usually called “volume." “displacement, aerodynamic volume or air volume — The weight of a mass of air equal to the aerodynamic volume of the airship in N. A. C. A. standard atmosphere at sea level. displacement (cubic piston)—The cubic volume displaced by a piston in its movement from bottom dead center to top dead center. Cubic piston displacement equals 3.1416 X radius of cylinder squared X length of stroke. displacement (total cubic)—The piston displacement plus DIS the volume of the combustion chamber (piston at top dead center). “disposable weight—See WEIGHT, DISPOSABLE (AIRSHIP). distillates are the naphtha products which are obtained by distilling crude oils. distortion means to twist, turn or deform anything from its natural shape or figure. distortion on maps and charts occurs because of the imper- fect methods available for projecting the curved surface of the globe onto a flat map or chart. distributor—A device used to complete the high tension (secondary) circuits to the various spark plugs at the proper firing time. *dive—A steep descent, with or without power, in which the air speed is greater than the maximum speed in horizontal flight. *divergence—A motion in which, after a disturbance from equilibrium, the body departs continuously, without oscil- lations, from its original state of motion. Dividers are an instrument similar to a drawing compass, used to scale off distances on charts, maps, parallelograms of force, etc. The instrument has two sharp points rather than one point and a lead, as in a drawing compass. "dock—A term sometimes applied to an airship shed. *.docking cradle—See CRADLE, DOCKING. *.docking rail—See RAIL, DOCKING. *.docking trolley—See TROLLEY, DOCKING. doldrums—A belt of low pressure and calms in the tropics. dope—The finish applied to aircraft cloth fabric, to shrink, preserve and cause air-tightness. Dopes are usually cellu- lose or collodion compounds, soluble in ether or acetone. "dope (airplane)—The liquid material applied to the cloth surfaces of airplanes to increase strength, to produce tautness by shrinking, and to act as a filler for maintaining air-tightness. "dope (airship)—The liquid material applied to rubberized airship fabric to increase gas tightness. In contrast with airplane dope, it does not cause shrinking. "dope (pigmented)—An aircraft dope to which a pigment has been added to make an opaque finish, or to protect it from the effects of sunlight. down draft is a draft sweeping down over an obstacle or a cool descending draft of air. The former is likely to be of the more violent nature. ‘downwash angle—See ANGLE, DownwASH. *drag—The component parallel to the relative wind of the total air force on an aircraft or airfoil. Its symbol is D. The "absolute drag" coefficient is CD as defined by the equation CD = ..., in which D is the drag, q is the impact D qS' pressure (= %pV2) and S is the effective area of the surface upon which the air force acts. In the case of an airplane, that part of the drag due to the wings is called "wing drag"; that due to the rest of the airplane is called HDRA "structural drag" or "parasite resistance." induced—That portion of the wing drag induced by, or resulting from, the generation of the lift. profile—That portion of the wing drag which is due to friction and turbulence in the fluid and which would be absent in a nonviscous fluid. & drag-The horizontal component of reaction produced when airfoils are thrust through the air. drag coefficient is the value of the drag in pounds of one square foot of wing area traveling at a velocity of one mile per hour at a given angle of attack. This leads to the formula D = KxAV2 where D = the drag in pounds Kx = coefficient of drag A = wing area in square feet V% = velocity squared. drag (parasite) is a collective term which refers to the drag produced by all parts of the airplane except the wings (useful lifting surfaces). *drag, mooring—A movable and/or variable weight, sus- pended from the after part of an airship's structure while moored at a mast, to aid in restraining the vertical and lateral motions of the stern of the airship. * drag rope—See ROPE, DRAG. *drag strut—See STRUT, DRAG. “drift—The lateral velocity of an aircraft due to air currents. drift—The movement away from the line of heading caused by cross winds. “drift angle—See ANGLE, DRIFT. “drift bar—A part of a drift meter or other instrument for indicating the apparent direction of motion of the ground relative to the fore-and-aft axis of the aircraft. It usually consists of a wire or arm which can be set along this direc- tion of motion. Cf. drift. *drift meter—An instrument for measuring the angle between the fore-and-aft axis of an aircraft and its path over the ground. One form consists of a drift bar provided with a suitable angular scale. (Cf. drift.) The instrument is graduated to read correctly when it is level. drift indicator—An instrument for determining the angle of departure from the aircraft heading, due to lateral velocity. *drip band—See FLAP, DRIP. *drip flap—See FLAP, DRIP. *drip strip—See FLAP, DRIP. *D-ring—A ring having (as the name implies) the shape of a capital D, to which rope suspensions are attached. drive fit—See FIT, DRIVE. *drogue—See ANCHOR, SEA. dry sump—See SUMP, DRY. *dry weight of an engine—See ENGINE, DRY WEIGHT OF. * duralumin—An alloy of aluminum which is much used in aeronautics, especially for the structure of airships and HDUR airplanes. Its chemical composition and physical proper- ties are about as follows: Copper, 3.5 to 4.5 per cent. Manganese, 0.4 to 1 per cent. Magnesium, 0.2 to 0.75 per cent. Aluminum, 92 per cent, minimum. Tensile strength, ultimate, 55,000 pounds per square inch. Tensile strength at elastic limit, 30,000 pounds per square inch. Elongation of 2 inches at ultimate strength (test speci- men /, inch wide), 18 per cent. Specific gravity not more than 2.85. duralumin, which is an aluminum alloy, is used extensively in wing construction and for the covering of wings and fuselages. It has about three times the strength of steel for the same weight. For covering, it is generally applied with a very smooth finish, which offers greatly reduced skin friction. Duralumin is usually fabricated with riveted construction. The corrugations in sheet duralumin, used for covering, add a great deal of strength without materi- ally adding weight. “dynamic factor—The ratio between the load carried by any part of an aircraft when accelerating and the correspond- ing basic load. * dynamic lift—See LIFT, DYNAMIC. "dynamic load—See LOAD, DYNAMIC. t * dynamic (or impact) pressure—The product /?pV”, where p is the density of the air and V is the relative speed of the air. It is the quantity measured by most air-speed instru- ments. Symbol is q. dynamic soaring—See SOARING, DYNAMIC. “dynamic trim—See TRIM, DYNAMIC. earth inductor compass—A direction indicator depending on the earth's magnetic field for the field of an electric generator. The generator brushes are set for a given course by a controller so that while the airplane remains on the course no current is generated and a galvanometer reads zero. Deviations from the course will cause read- ings on the galvanometer to the right or left of zero, indi- cating that the airplane is off the course to the right or left. eccentric means not having the same center. In regard to cams, the points on the contour are not equidistant from the center. Used to obtain other than true circular motion. waze 2a Mezzzzz zs a 77%ave a zoº &zz/A2 cº->4. The Vertical Tail Surfaces of a Great Lakes Dive Bomber. “effective helix angle—See ANGLE, EFFECTIVE HELIX. * effective thrust—See THRUST, EFFECTIVE. efficiency—The ratio of output to input, or the effectiveness to design. elasticity, modulus—See MODULUS OF ELASTICITY. elastic limit of a material is the limit of strain beyond which the material will rupture. As long as the modulus of elas- ticity remains nearly constant the elastic limit is not reached. electrical conductors—See CONDUCTORS, ELECTRICAL. electric current—See CURRENT, ELECTRIC. electric generator—See GENERATOR, ELECTRIC. electricity, static is electricity at rest or stationary, but with- out any current flow. Sufficient static electricity may be dissipated in the form of a spark by grounding the object which is in this condition. Static discharges of this nature are responsible for many fires. The dragging chain on a gasoline laden truck is used to continuously discharge static electricity at the ground to prevent dangerous accumulations which may be accidentally discharged near the fuel. electric motor—See MOTOR, ELECTRIC. electrode—An electrical conductor generally used at a ter- minal position in a circuit (points on a spark plug, carbons in an arc lamp, filler electrode in arc welding, etc.). electrode (fluxed or coated)—A metal electrode (filler elec- trode as in electric arc welding) on which the flux has been applied by spraying, dipping, or painting. electromagnetic inductance is the tendency for electric cur- rents to flow in a conductor when the conductor is moved across a magnetic field to cut the lines of force in that field. electromagnetism is the magnetism produced around a con- ducting medium when a current flows through it. electromotive force is the difference of electrical potential or pressure between two bodies or parts of the same body. electrolyte is the mixture of concentrated sulphuric acid (1 part) and distilled water (2% parts) in a storage battery. “elevator—A movable auxiliary airfoil, the function of which is to impress a pitching moment on the aircraft. The ele- vator is usually hinged to the stabilizer. * elevator angle—See ANGLE, ELEVATOR. empennage—A collective name for the tail surface group (rudder, elevators and stabilizers). empirical formula is one founded upon experiment or experi- ence without due regard to science or theory. emulsion is a mechanical mixture of liquids (and usually air) made by beating or whipping the liquids together. An emulsion occurs when the liquids are not chemically suited to combine in the form of another chemical. The introduction of air through the air bleed of a Stromberg carburetor produces an emulsion with the gasoline, which is discharged through the main discharge nozzle. emulsion test is used to determine the time required for oil to separate completely from an emulsion with distilled water. END end boiling point is the temperature at which the last drop of gasoline will be distilled. *endurance—The maximum length of time an aircraft can remain in the air at a given speed and altitude. energy is the ability to do work. Gasoline contains heat energy, which, when released, will accomplish work. Water and objects at high levels have potential energy which will do work when gravity is allowed to draw them down. energy, kinetic—See KINETIC ENERGY. “engine altimeter—See ALTIMETER, ENGINE. *engine, barrel-type—An engine having its cylinders ar- ranged equidistant from and parallel to the main shaft. engine, cam—An engine driven by the action of rollers acting on the surface of a two lobe cam, mounted on a main shaft. “engine controls—See CONTROLS. “engine, dry weight of an—The weight of the engine, includ- ing carburetor and ignition systems complete, propeller hub assembly, reduction gears, if any, but excluding ex- haust manifolds, oil, and water. If the starter is built into the engine as an integral part of the structure its weight shall be included. engine, Diesel—An internal combustion engine depending upon the heat of compression for ignition. The oil fuel is injected under high pressure and no ignition system or carburetor is required. engines, geared, are engines which have a gear train to an auxiliary shaft which carries the propeller. This arrange- ment permits of different speeds of rotation for the engine operation and the propeller. engine, internal combustion—A mechanical device designed to convert the latent heat energy of fuel into mechanical work. “engine, inverted—An engine having its cylinders below the crankshaft. * engine, left-hand—An engine whose propeller shaft, to an observer facing the propeller from the antipropeller end of the shaft, rotates in a counterclockwise direction. “engine, radial—An engine having stationary cylinders ar- ranged radially around a common crankshaft. “engine, right-hand—An engine whose propeller shaft, to an observer facing the propeller from the anti-propeller end of the shaft, rotates in a clockwise direction. “engine, rotary—An engine having revolving cylinders ar- ranged radially around a common fixed crankshaft. *engine, supercharged—An engine with mechanical means for increasing the cylinder charge beyond that normally taken in at the existing atmospheric pressure and tem- perature. *engine, vertical—An engine having its cylinders arranged vertically above the crankshaft. *engine, V-type—An engine having its cylinders arranged in two rows, forming, in the end view, the letter "V.” WERTICAL TYPE W-TYPE Example – Cirrus — Menasco No American example AERONCA E-1 13B -- 36 H. P. Two cylinder opposed air cooled PACKARD 24 CYLINDER – 1250 H. P. X-Type liquid cooled Types of Cylinder Arrangement for Various Designs. RANGER W-770SG -- u2O H. P. -2 cylinder inverted, W-type air cooled CURTISS CONQUEROR (GEARED) –– 675 H. P. 12 cylinder, W-type, liquid cooled. WARNER SCARAB -- 125 H. P. 7 cylinder radial air cooled Types of Cylinder Arrangement for Various Designs. sº 2 Iſſº & ={2} ºſ, "H". }{T. º *— TWIN WASP A (GEARED) 750-800 H. P. it cylinder double row radial air cooled WRIGHT WHIRLWIND -- 175 H. P. 5 cylinder radial air cooled CURTISS CHALLENGER -- 185 H. P. 6 cylinder radial air cooled Types of Cylinder Arrangement for Various Designs. *š, \ \ CA:/y7&A2A7A7/. /*22ce A/E/zºº/7 & * Airplane Flying in a Banked Turn (Spartan). § { 4%véese cavazeeze. § S N Kozze rºaſes, 72°22/22x- _47×eorzººs ze= coazzerzse ze \ | 2 vox. 5.7×2 A-22 4A/7szz, cowzza, | ~~~~ 47%.2 7%-72 ºvº-ZAF 2), Zazzeavce 2- E-ITI ^2 <^^/7 &azz.27&LE //, /ezzº avy- | ſ * Sy § | | Z.2e2.57- T - T - :- — — —s- | Af ~<2&v=ayrava’, *:::, - – – – ---- - - —Zeºz- & \ 7% .5&eAxxes | // >%zazz /r/, /r/za Azzazz. AZ/Z &AEO/Y & cºyzzoz. –––7%zazz cass/s //4/4/y The Modern Gyroplane. ENG * engine, W-type—An engine having its cylinders arranged in three rows, forming, in the end view, the letter “W.” Sometimes called the "broad-arrow type." engine, X-type—An engine having its cylinders arranged in four rows, forming an “X” in the end view. *entering edge—See LEADING EDGE. *envelope—The outer covering of an aerostat, usually of fabric. It may or may not be also the gas container. It may be divided by diaphragms into separate gas compart- ments or cells, and it may also contain internal air cells or ballonets. equation is an algebraic expression of equality. For exam- ple: S = V × T. The Distance S always equals the Velocity times the Time, regardless of the values for V and T. equator—A great circle on the surface of the earth, whose points are equidistant from the poles. The equator is the zero parallel of latitude. equation of time is the difference between apparent and mean time, and may be found for any moment from the Nautical Almanac. equinox (autumnal) is that one at which the sun passes from the northern to the southern declination. equinox (vernal) is that one at which the sun passes from the southern to the northern declination. The vernal equi- nox is also designated as the first point of Aries, and is used as the origin of reckoning right ascension. “equipment, ground—See GEAR, GROUND. etching (propeller)—A process of treating the surface of metal propellers to bring out evidence of flaws and cracks. evaporation — The absorption by the air of water vapor given off at the surface of liquids, or the evaporation of fog, clouds, etc. evaporimeter is a device to measure the rate and amount of evaporation. fabric—The cloth (usually a high grade cotton) used for covering on airplanes. *fabric, balloon–The finished material, usually rubberized, of which balloon or airship envelopes are made. biased—Plied fabric in which the threads of the plies are at an angle to each other. parallel—Plied fabric in which the threads of the plies are parallel to each other. “fabric, gas-cell—The fabric used in gas cells of rigid air- ships, usually goldbeater's skin fabric, q.v. *fabric, goldbeater's skin—A gas-containing fabric consist- ing of a layer of light, fine, strong cloth, usually cotton, to which one or more layers of goldbeater's skins have been cemented. The skins are on the inside and are usually further protected by a coat of fine varnish. Usually used in the gas cells of rigid airships. *factor, dynamic—See DYNAMIC FACTOR. *factor of safety — The ratio of the ultimate strength of a FAH member to the maximum probable load in that member in actual use. Fahrenheit Scale—The temperature scale on which water freezes at 32° above zero and boils at 212° above zero. "fairing—An auxiliary member or structure whose primary function is to reduce head resistance or drag of the part to which it is fitted (without, in general, contributing strength). *fairing wire—See WIRE, FAIRING. falling leaf consists in executing a stall as for a spin. With the stick all the way back and neutral ailerons, the rudder action is reversed in time to prevent the first turn of a spin. This method of control causes a series of saucer-like Swings from side to side without changing the general direction of heading. Altitude is lost with each oscillation, because the airplane is continuously in a stall. false rib—See RIB, FALSE. farad is the unit of electrical capacity, being the capacity of a condenser when it will hold one coulomb of electricity when a pressure of one volt is applied across it. fathom is a nautical term of water depth measurement equal to six feet. fatigue in a part of a structure or machine is due to a con- tinued repetition of a stress. Repeated reversals of stress, much less than the elastic limit, will cause fatigue and ultimate fracture. Ferrel’s Law—"When a mass of air starts to move over the earth's surface it is deflected to the right in the northern hemisphere and to the left in the southern hemisphere, and tends to move in a circle whose radius depends upon its velocity and its distance from the equator." ferro-magnetic substances are strongly magnetic. Ferrous metal—See METAL, FERROUS. ferrule—Metal fittings or wire wrappings designed to pre- vent splitting of wooden parts or loosening of wire ter- minals, etc. fiducial points are the boiling and freezing points on a ther- mometric scale. *field-handling frame—See FRAME, FIELD-HANDLING, filler metal—See METAL FILLER. filleting is used to increase the streamline possibilities of aircraft by rounding out rough joints (wings to fuselage, etc.) with smooth curves. *filling sleeve—See SLEEVE, FILLING. *fin—A fixed surface, attached to a part of the aircraft, paral- lel to the longitudinal axis, in order to secure stability; for example, tail fin, skid fin, etc. Fins are sometimes adjust- able. *fin carrier—See CARRIER, FIN. fineness (of streamline)---The proportion in cross-section resistance of a part. *fin girder—See GIRDER, FIN. *finger patch—See PATCH, INGER. firepoint is the degree of tcrºperature at which oil will give FIR off sufficient vapor to ignite and burn continuously when exposed to a naked flame. *fire wall—A fire-resistance transverse bulkhead, so set as to isolate the engine compartment from the other parts of the structure and thus to reduce the risk from fire in the engine compartment. firing order—The series or rotation in which the cylinders of an engine fire. fit (drive)—Two pieces of such close dimensions that it is necessary to drive one piece into the other with blows. fit (press)—Two pieces of such close dimension that pres- sure is required to assemble the pieces. An arbor press is used to assemble such parts. fit (running)—Two parts so fitted that free movement of the parts exists. fit (shrink) requires the expansion of one part by heat so that the other part may be placed within it. As the outer part contracts as a result of cooling, a very tight fit is secured. *fitting—A generic term for any small part used in the struc- ture of an airplane or airship. If without qualification, a metal part is usually understood. It may refer to other parts, such as "fabric fittings." fitting—Joining individual parts to make a complete as- sembly. *fixed fuel tank—See TANK, FIXED FUEL. *fixed power-plant weight for a given airplane—See WEIGHT, FIXED, POWER-PLANT, FOR A GIVEN AIRPLANE. * fixed surface—See FIN. *fixed weight—See WEIGHT, FIXED (AIRSHIP). flange refers to the web stiffening parts of I-beam sections, channel sections, projections on castings for bolting, etc. “flap, drip—A strip of fabric attached by one edge to the envelope of an aerostat so that rain runs off its free edge instead of dripping into the basket or car. It also assists in keeping the suspension ropes dry and non-conducting. Also called "drip band" and “drip strip." *flap pressure—A flap valve fitted in the outer cover or en- velope of a rigid airship and arranged to permit the rapid flow of air in and out—particularly inward. The purpose is to facilitate the rapid equalization of the pressure of the air within the envelope with that of the surrounding all’. flashpoint is the degree of temperature at which vapor is given off by oil in sufficient quantity to ignite momentarily (flash) when exposed to a naked flame. *flight, cross-country — A flight which necessitates leaving the vicinity of a regular landing field. *flight indicator—See INDICATOR, FLIGHT. *flight path—The path of the center of gravity of an aircraft with reference to the earth. - *flight recorder—See RECORDER, FLIGHT. FLO *float—A completely enclosed water-tight structure attached to an aircraft in order to give it buoyancy and stability when in contact with the surface of the water. In float seaplanes the crew is carried in a fuselage or nacelle sepa- rate from the float. The term "pontoon" is now obsolete. float (carburetor) is usually a hollow, air-tight object de- signed to control the fuel flow from the feed line to the carburetor bowl by governing the action of the needle valve. Cork floats are sometimes used in inexpensive automobile carburetors. “flotation gear—See GEAR, FLOTATION. flutter is the vibration of wing tips, wires, etc. flux—Material used in welding to retard the formation of oxides, nitrides, etc., in the weld. In arc welding the flux is used to retard the rate of cooling of the metal. In arc welding the heat of the arc is quite localized so that too rapid cooling would cause an exceedingly brittle weld. flux (electrical)—The movement of lines of force. *flying boat—A form of seaplane supported, when resting on the surface of the water, by a hull or hulls providing flotation in addition to serving as fuselages. For the cen- tral hull type, lateral stability is usually provided by wing-tip floats. The term “boat seaplane" is now obso- lete. fog—Fog is a cloud formation of condensed moisture, but close to or in contact with the earth. foot pound—The unit of work, being the expenditure of energy necessary to raise a weight of one pound through a distance of one foot against the action of gravity. force, centrifugal—See CENTRIFUGAL FORCE. force, centripetal—See CENTRIPETAL FORCE. force, coercive is the force necessary to demagnetize a magnet. forces, composition of See COMPOSITION OF FORCES. “force, cross-wind—The component, perpendicular to the lift and to the drag, of the total air force on the aircraft or any part thereof. Its symbol is C and its absolute co- efficient CC is defined by C C C - as where q is the impact pressure (=%pV*) and S is the effective area of the surface upon which the air force actS. force, electromotive—See ELECTROMOTIVE FORCE. force, lines of See LINES OF FORCE. force, moment of See MOMENT OF FORCE. forces, resolution of See RESOLUTION OF FORCES. force, resultant—See RESULTANT OF FORCES. form, rib—See RIB, FORM. *frame, field-handling—A portable frame which may be at- ºueſ deºs| 9pºqepțIosuo?)9ų L DITZ2 Æſº ===z• Þa E. ºueſ dig Kuenſiw e jo 93 elesnae Iººns pºPlºA ºd L Sºgº/zzzZ 2/4/5740 ºwoazzzz zzzzzzzzzzzzzz） §. 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Aº cº =№_c >=7~~ły&=z\, sººſ zyxosº zrºz 2，457zzaw&>ooo/Mazy FRA tached to an airship when it is on the ground and which is intended to afford a grasp to more men than could get on the handling rails of the cars. These frames are rarely carried when in flight. *framing, stern—All framework, aft of the cruciform girder, necessary to complete the shape and contour of a rigid airship. “free balloon—See BALLOON, FREE. *free-balloon net—See NET, FREE-BALLOON. freezing point—The point in the temperature scale at which water congeals or turns to a solid. Frise type aileron—See AILERON, FRISE TYPE. front elevation drawing shows the true shape of an object as viewed from the front. frost—Frozen dew. *fuel (or oil) consumption, specific—The weight of fuel (or oil) consumed per brake horsepower-hour. fuel level (carburetor)—The fuel level in reference to the top of the main jets (usually about 9%” below the top of main jet). *fuel tank, fixed—See TANK, Fixed FUEL. fulcrum is the pivotal support about which any lever turns. *full load—See LOAD, FULL. fuse is a soft metal unit in an electrical circuit, and it has a low melting point. The fuse is designed to melt and break the circuit if the current value reaches a point which will damage or rupture the circuit. *fuselage—The structure, of approximately streamline form, to which are attached the wings and tail unit of an air- plane. In general it contains the power plant, passengers, cargo, etc. *fuselage, monocoque — A type of fuselage construction wherein the structure consists of a thin shell of wood, metal, or other material, supported by ribs, frames, belt frames, or bulkheads, but usually without longitudinal members other than the shell itself. The whole is so dis- posed as to carry the stresses to which the structure is subjected. *gap—The distance between the planes of the chords of any two adjacent wings, measured along a line perpendicular to the chord of the upper wing at any designated point of its leading edge. Its symbol is G. galvanometer—A very sensitive instrument which measures the intensity (voltage) of an electric current and also to detect the presence of very small current values. gas bag—See HULL (AIRSHIP) and CELL, GAS. gas capacity, nominal—See CAPACITY, NOMINAL GAS. gas cell—See CELL, GAS. gas-cell alarm—See ALARM, GAS-CELL. gas-cell fabric—See FABRIC, GAS-CELL. gas-cell, net—See NET, GAS-CELL (RIGID AIRSHIP). gas container—See CELL, GAS. gasoline is a mixture of saturated hydrocarbons produced by redistilling the gasoline naphthas (crude gasoline) which has been distilled from crude petroleum. Crude * * * ¥ jk •ºr Yºr GAS petroleum is composed of different compounds of hydro- gen and carbon in series, and also contains small quanti- ties of foreign elements, oxygen, nitrogen and sulphur. gasoline (blended) is produced by mixing appropriate quantities of various gasoline grades to obtain a fuel to meet definite specifications. gasoline, casing head, is made by condensing from natural gas and the uncondensed gases from crude stills. The gases are gradually compressed up to about 350 pounds per square inch and the liquid gasoline is brought down by cooling. *gas shaft—See SHAFT, GAS. *gas-shaft hood—See HOOD, GAS-SHAFT. *gassing—The operation of replenishing a balloon with fresh gas to increase the purity or to make up for loss of gas. *gassing factor—The quantity of aerostatic gas required to maintain an aerostat for one year. It is ordinarily ex- pressed as a percentage of the gas volume. "gas volume—See voLUME, GAS (AIRSHIP). *gear, flotation—An emergency gear attached to a landplane to permit alighting on the water and to provide buoy- ancy when resting on the surface of the water. gear, idler is a gear placed between two other gears to transfer motion without changing the direction of rota- tion. *gear, ground—The gear, or equipment, necessary for the landing and handling of an airship on the ground. gear, pinion is the smaller of two geared wheels. generator, electric is a machine which transforms mechani- cal power into electrical power by utilizing the principles of electromagnetic induction. geographical poles—See POLES, GEOGRAPHICAL. *girder, box—Any girder of rectangular section. Frequently used to refer to the rectangular, longitudinal members in the keel of a rigid airship from which fuel tanks and gas bags are suspended. *girder, cruciform—The structure, consisting of vertical and horizontal transverse girders, which is fitted at the stern of a rigid airship for the purpose of supporting the in- board ends of the stern posts of the fins or the rudder posts. It may be integral with the stern posts which form the after ends of the fins. *girder, fin—A girder of a rigid airship which goes to make up the fin. * girder, propeller reinforcing—A light additional member fitted in the structure of a rigid airship to reinforce those areas of the outer cover which are affected by the pro- peller wash. * girder, walkway—The girder forming the support of a walkway through the keel or in other localities in a rigid or Semirigid airship. *gland—A short tube fitted to an envelope or gas bag in such a manner that a rope or line may slide through without leakage of gas or air. *gland, manometer-tube—A gland fitted to the envelope of GLA an aerostat to form a gas-tight connection for the tube leading to the manometer in the car. Same as “pressure- tube gland." *gland, pressure-tube—See GLAND, MANOMETER-TUBE. glass (usually of the non-shatterable type) and celluloid are used in the construction of windows and wind screens. Non-shatterable glass is made by either casting fine crossed wires in the glass, or by fusing two thin layers of glass to a center film of tough material. Both kinds are designed to hold the pieces together in case of breakage. *glide—A descent with reference to the air at a normal angle of attack and without engine power sufficient for level flight in still air, the propeller thrust being replaced by a component of gravity along the line of flight. Also used as a verb. *glider—A form of aircraft similar to an airplane, but with- out a power plant. gliding range is the ultimate point that can be reached from a given height by an aircraft under normal conditions. glue (casein) is made from the casein which is precipitated from sour milk curds by the use of hydrochloric acid. Casein glue is simple to mix, easy to apply, and is highly resistant to water. glycerin is frequently used in solution with water as an antifreeze mixture. A solution of 40% glycerin will pro- tect the mixture down to 0° Fahrenheit and freezes solid at about 10° below 0° Fahrenheit. gnomonic projection—A projection from the center of the earth of the earth's surface onto a plate tangent to the earth's surface. * goldbeater's-skin fabric—See FABRIC, GOLDBEATER’s-SKIN. *gondola—The car of an airship. This use of the word is borrowed from the Italian via the German. "Car" is to be preferred. *gore—The portion of the envelope of a balloon or airship included between two adjacent meridian seams. * grab line—See LINE, HANDLING. gradient of a slope is a fraction formed by a vertical in- terval in the numerator and the horizontal distance (hori- zontal equivalent) between contour lines in the denomi- nator. gradient (pressure)—See PRESSURE GRADIENT. gradient (vertical temperature)—The rate at which pure, dry air is found to be cooled with elevation—1° Fahren- heit per 300 feet, approximately. grain is a unit of weight, being 1/7,000 of a pound avoir- dupois, and is equal to .0648 of a gram. great circle—See CIRCLE, GREAT. gram—calorie (gm, cal.), called the 15° small calorie, is the heat required to raise one gram of water from 14.5° Centigrade to 15.5° Centigrade. graphical scale—See SCALE, GRAPHICAL. GRA gravity—The force of the earth's attraction upon a body. It decreases with increase of distance from the earth. The present altitude range of aircraft is not sufficient to cause an appreciable decrease in the attraction of gravity for an airplane. gravity, acceleration—See ACCELERATION OF GRAVITY. gravity, specific—The relative density of substances per unit volume compared to the density of water for the same unit volume. Thus, if the density of water is one gram per cubic centimeter and one cubic centimeter of gasoline weighs .75 grams, then the gasoline is said to have a specific gravity of .75. Specific gravity is a ratio and is, therefore, represented as a number only. Greenwich Apparent Time (G. A. T.) signifies the appar- ent sun time at meridian of Greenwich. Greenwich Apparent Time plus east longitude equals Local Apparent Time. Greenwich Apparent Time minus west longitude equals Lo- cal Apparent Time. Greenwich Mean Time plus east longitude equals Local Mean Time. Greenwich Mean Time (G. M.T.) signifies clock time at meridian of Greenwich. Greenwich Mean Time minus west longitude equals Local Mean Time. grinder is a machine used to impart a high finish and very accurate dimensions to parts in the process of manufac- ture. Cylinders, crankshafts, and piston pins are good examples of finish ground work. grommet—A small ring of cord. gross lift (airship)—See LIFT, GROSS (AIRSHIP). ground angle—See ANGLE, LANDING. ground cloth—See CLOTH, GROUND. ground crew—See CREW, LANDING. ground equipment—See GEAR, GROUND. ground gear—See GEAR, GROUND. *ground speed—See SPEED, GROUND. ground speed—The actual speed of an airplane over the ground. *ground-speed meter—An instrument for measuring the speed of an aircraft relative to the ground. In present types of instruments some reference line in the instru- ment must first be set parallel to the apparent direction of motion of the aircraft with reference to the ground before the speed measurement is made. This is usually accomplished by the use of a drift meter, the adjustment of which automatically orients the ground-speed meter properly. Thus both the magnitude and direction of the motion of the aircraft with reference to the ground are obtained. guide (valve stem)—See VALVE STEM GUIDE. gusset is a relatively small triangular brace used to strengthen corners in a structure. They are used prin- cipally at wing rib joints. gusty air—See AIR, GUSTY. . GUY *guy, yaw—See LINE, YAW. gyroscope—A rotating wheel or disc whose characteristic tendency is to rotate about any axis about which it is turned as a whole. A gyroscope is the fundamental unit of a turn indicator. "gyroscopic turn indicator—See INDICATOR, GYROSCOPIC TURN. “handling line—See LINE, HANDLING. *hangar—A shelter for housing aircraft. More properly ap- plied to heavier-than-air craft. half round section is a solid structural section, flat on one side and curved on the other. hardening, case—See CASE HARDENING. hard pine is a tough, uniform wood, particularly applicable to members like the longerons of the fuselage. “harness, mooring—A system of webbing bands, fitted over the top of the envelope of a balloon, to which are at- tached the mooring ropes. Usually found only in kite balloons or observation balloons. haze is caused by very fine particles of moisture, smoke and dust suspended in the air. heading (airplane)—The direction of the airplane's longi- tudinal axis. head wind—A wind blowing from the direction of the air- plane's heading. heat—Molecular energy which is measured by the effect it produces. *height, pressure—The altitude at which the gas cells of a rigid airship are full, or the gas bag of a non-rigid air- ship is completely full of gas. “helicopter—A form of aircraft whose sole support in the air is derived directly from the vertical component of the thrust produced by rotating airfoils. Henry, the, is the unit of self-induction or the inductance when the induced electromotive force is one volt while the inducing current varies at the rate of one ampere per second. hickory, which is tough, springy and hard surfaced, is a favorite material for skids and control levers. high pressure area—An area of high barometric pressure, usually accompanied by clear pleasant weather. high tension coil—See COIL, HIGH TENSION. *hog—A distortion of an airship in which the longitudinal axis becomes convex upward so that both ends droop. honeycomb is a sieve-like design used to secure maximum surface area in solution radiators, and also as a device to smooth the air flow in wind tunnels. *hood, gas-shaft—A hood, or cowl, located on the outer cover of a rigid airship at the outer end of a gas shaft. It is usually made of light wood and fabric and is faced to facilitate the escape ºbf gas. Sometimes called “ex- haust-gas hood." In view of the possibility of confusion with the parts of an engine exhaust system, it is believed that “gas-shaft hood" is to be preferred. - *hood, maneuvering-valve—A hood, or cowl, located on the outer cover of a rigid airship just over a maneuvering HOO valve. It is usually made of light wood or fabric and is faced to facilitate the escape of gas. *hood, valve—The appliance, having the form of a hood or parasol, which protects the valve of an airship or bal- loon against rain. Also called "valve cover" or “bon- net." hook is the metal hook used at the nose of gliders to hold the launching elastic. horizon—The horizontal plane passing through an observ- er's position on the earth and tangent to the earth at that point. horizon (artificial)—A self contained artificial reference (bubble or pendulum) within a sextant to be used for a horizon when the natural horizon is obscured, or when an airplane is at too great an altitude to determine the natural horizon with accuracy. horizon dip—See DIP (OF THE HORIZON). *horn—A short lever attached to a control surface of an air- craft. For example, aileron horn, rudder horn, elevator horn. horse latitudes—Belts of high pressure at approximately 30° north and south latitude. horsepower, one—The expenditure of energy necessary to raise 550 pounds one foot in one second against the ac- tion of gravity. "horsepower of an engine, maximum—The maximum horse- power which an engine can develop. "horsepower of an engine, rated—The average horsepower developed by an engine of a given type in passing the standard 50-hour endurance test. hour angle is that angle at the celestial pole between the meridian intersecting any given point and the meridian intersecting the center of the sun. hour (of right ascension) equals 15° of arc. hovering is cruising at a speed just above stalling speed in order to pass over the earth as slowly as possible. humidity (absolute)—The actual amount of water vapor in the air, expressed in grains per cubic foot. humidity (relative)—The percentage of moisture in the air under given conditions of temperature compared to amount required to saturate the air. "hull (airship)—The main structure of a rigid airship, con- sisting of a covered elongated framework which incloses the gas cells and supports the cars and equipment. May also be applied to the complete buoyant unit of any aero- stat. In this latter sense sometimes called “gas bag." "hull (seaplane)—The portion of a flying boat which fur- nishes buoyancy when in contact with the surface of the water. It contains accommodations for the crew and pas- sengers, usually incorporating the functions of a float and fuselage in one unit. hydroglider is a float equipped glider for water landings and take-offs. hydrometer (syringe) is a graduated glass syringe used HYD to ascertain the specific gravity of storage battery solu- tions. hydrosphere—The water parts of the earth. hygrometer—An instrument for determining relative hu- midity by means of the expansion and contraction of human hairs. Human hair is very sensitive to moisture. hygrometry is the study of moisture conditions of the at- mosphere. hygrograph—A recording hygrometer. I-beam section is the cross section of a structural member which is made in the form of a capital I. This section may be solid or built up from plate and angles, and the web may be solid material or latticed. I-beam section spars are also built up from wood. idler gear—See GEAR, IDLER. ignition—The process of setting fire to fuel or fuel vapor in the internal combustion engine. Immelman turns are made to secure the quickest possible reversal of direction of an airplane in flight. There are several modifications of this maneuver, which vary from kicking hard rudder while in a vertical zoom to half rolling from any position beyond a vertical zoom. These variations depend upon the amount of power and ma- neuverability of the ship. “impact pressure—See DYNAMIC (OR IMPACT) PRESSURE. impulse—A force causing a body to gain or lose momentum. inch equals 2.54 centimeters. *inclinometer—An instrument for indicating the attitude of an aircraft. Inclinometers are termed fore-and-aft, lat- eral, or universal, according as they indicate inclination on the vertical plane through the fore-and-aft axis, or in the vertical plane through the lateral axis, or in both planes, respectively. *inclinometer, absolute—An instrument which indicates the attitude of an aircraft with reference to the vertical. The indications of instruments of this type usually depend on gyroscopic action. *inclinometer, relative—An instrument which indicates the attitude of an aircraft with reference to apparent gravity, i. e., to the resultant of the acceleration of the aircraft and that due to gravity. index correction (sextant) is necessary because the sextant does not always read zero when so set. *indicator, air-speed—See AIR-SPEED METER. *indicator ballonet-fullness—An instrument for indicating the volume of air in a ballonet. *indicator, flight—An instrument in which a lateral inclinom- eter, a fore-and-aft inclinometer, and a turn indicator are combined to form a compact unit. *indicator, gyroscopic turn—A turn ind;...ator dependent on gyroscopic action. *indicator, pitch—An instrument for indicating the existence of a pitching velocity of an aircraft. Cf. turn indicator. *indicator, static turn—A turn indicator actuated by the dif- ference in pressure between static tubes mounted near IND the wing tips equidistant from the plane of symmetry and in a plane parallel to the lateral axis. *indicator, turn—An instrument for indicating the existence of an angular velocity of turn of an aircraft about the normal axis. In horizontal flight it indicates the presence of a yawing velocity. "Turn meter" is the term applied to certain types. *indraft (inflow)—The flow of air from in front of the pro- peller into the blades. *induced drag—See DRAG, INDUCED. inductance is that quality in an electrical circuit which tends to oppose any change in the flow of electricity. inductance, electromagnetic—See ELECTROMAGNETIC INDUC. TANCE. inductance, mutual—See MUTUAL INDUCTANCE. induction—The process of creating electrical pressure or potential through the relative movement of a conductor and electrical lines of force. *induction compass—See COMPASS, INDUCTION. induction compass—See EARTH INDUCTOR COMPASS. induction, self—See SELF INDUCTION. induction system includes the carburetor and all intake manifolds designed to carry a fuel mixture to the cylin- ders of an engine. inertia is that property of matter by virtue of which it tends to remain at rest or, if in motion, to continue in the same direction unless acted upon by an external force. “inflation—The act of filling a balloon or airship with gas. “inflation manifold—See MANIFOLD, INFLATION. *inflation net—See NET, INFLATION. “inflation sleeve—See SLEEVE, INFLATION. “inflation tube—See TUBE, INFLATION. *inflow—See INDRAFT. initial boiling point is, the temperature at which the first drop of gasoline will come over in a standard type con- denser. - insolation—Short wave solar radiation, or the process by which the sun's heat reaches the earth. *inspection window—See WINDow, INSPECTION. "intermediate longitudinal—See LONGITUDINAL, INTERMEDIATE. *intermediate transverse—See TRANSVERSE, INTERMEDIATE. interplane aileron—See AILERON, INTERPLANE. interpolation—Using known figures to estimate probable figures which lie between the known quantities. Devia- tion 6°W at 30°. Deviation 4° W at 60°. Interpola- tion determines that the probable deviation at 45° is 5° W, or half way between the two. interrupter—Circuit breaker or breaker points in the pri- mary circuit of a magneto. intersection—The common point of two or more lines which cross. When plane surfaces intersect the intersection is a straight line. When two curved surfaces or one curved and one plane surface intersect the intersection is a curved line. interstate or foreign air commerce means air commerce be- º Pº - S T ,4 A.' Z2 SK The Internal Mechanism of the Bank and Turn In- N išSSN TURN & BANK INDICATOR PIONEER INSTRUMENT COMPANY, BROOKLYN, NEW YORK dicator. / º % SS Sº J. -! / % º Fº --- 2% Z// | sº| VN i | i NC z j _---—— -— -— — —- - - - - ~ VENTUR TUBE TYPE 74-B-900 3855- sº Actual Size *TRA-GHT - ºlºr-T wºº - * * LEFT Tu- LEFT Turºr- —- Q–- --------ºr rººt ---------- -º-º-º-º- tºo ºur----- TURN & BANK INDICATOR INDICATIONS Poween Ms. Ruwent company, Brooklyn, New York The Turn and Bank Indicator in Operation. * f INT tween any State, Territory or possession, or the District of Columbia, and any place outside thereof; or between points within the same State, Territory or possession, or the District of Columbia, but through the air space over any place outside thereof; or wholly within the air space over any Territory or possession or the District of Co- lumbia. - intrastate—Between points wholly within one State. "inverted engine—See ENGINE, INVERTED. inversion (temperature)—A condition of the atmosphere, such that there is a rise in temperature with increased al- titude instead of a drop. * inverted flight is simply flying an airplane on its back. The pilot must choose a new neutral position for the stick, because the wings, due to their cambered design and angle of incidence, have an entirely different aero-dy- namic reaction in such a position. isobars—Lines connecting points on a weather map having equal barometric pressure (usually solid lines). isogonic chart—See CHART, ISOGONIC. isogonic lines—Lines on a chart or map joining places of equal variation. isotherms—Lines on a weather map connecting places hav- ing equal temperature (usually dotted lines). jackstay—A longitudinal rigging provided to maintain the correct distance between various parts on fittings on an aeroStat. jet drain cup (carburetor) are small cups or settling cham- bers screwed into the carburetor under the fuel passages to the jets. These cups collect foreign substances and water, and can be removed for cleaning. jet, main—See MAIN JET. jet, metering—See METERING JET. jig is a pattern, form or framework accurately dimensioned and aligned in which identical structures or parts can be produced to meet a standard. joiner (wood) is a wood working machine used to finish the edges (narrow dimension) of a board. Joule is the unit of electrical energy or work done, being the amount of energy necessary to cause the flow of one coulomb of electricity under a pressure of one volt. *keel (airship)—The assembly of members at the bottom of the hull of a semi-rigid or rigid airship which provides special strength to resist hogging and sagging and also serves to distribute the effect of concentrated loads along the hull. It may be a simple Galls chain, as in some semirigids, or a very extensive structure inclosing the corridor, as in most rigids. keel surface—All surface to be seen in the side view of an airplane. kilogram equals 1,000 grams equals 2.204 pounds. kilogram-calorie (kg.-cal.) is .01 of the heat required to raise the temperature of one kilogram of water from 0° Centigrade to 100° Centigrade. kilometer is one thousand meters. KIL kilowatt—1,000 watts. Equals 1.34 h. p. kinetic energy is the capacity of a moving body to perform work and is equal to the weight times the velocity squared divided by two times the acceleration of gravity. *king post—The main compression member of a trussing system applied to support a single member subject to bending. - *kite—An aircraft heavier than air, restrained by a tow- line and sustained by the relative wind. *kite balloon—See BALLOON, KITE. knot is a nautical mile (6,080 feet), but refers to speed or velocity only and is not used as a measure of distance. knuckle pin—The pin in the bearing attachment of articu- lated connecting rods to the master connecting rod. . *kymograph—An instrument for recording the angular oscil- lations of an aircraft in flight with respect to axes fixed in space. The reference direction is usually given by a gyroscope or a beam of sunlight. 4. lag (altimeter)—The amount of difference in actual alti- tude reading, caused by the inability of the altimeter to accommodate itself to rapid changes in altitude. "laminated wood—See WOOD, LAMINATED. landing is the act of discontinuing flight by returning an aircraft to the ground or water surface. - *landing angle—See ANGLE, LANDING. - - landing (blind)—A landing made under circumstances such that no visibility exists. “landing crew—See CREW, LANDING. landing (dead-stick) is a landing under circumstances such that the propellers have stopped turning. ~ *landing field—A field of such a size and nature as to permit of aircraft landing and taking off in safety. It may or may not be part of an airport. *landing field, emergency—A locality, either of water or land, which is adapted for the landing and taking off of aircraft, but which is not equipped with facilities for shelter, supply, and repair of aircraft and is not used regularly for the receipt or discharge of passengers or cargo by air. landing. (forced) is a landing forced on the pilot because of engine failure, structural failure, lack of fuel, fire, weather, etc. The majority of forced landings are a re- sult of engine failure. *landing gear—The understructure which supports the weight of an aircraft when in contact with the surface of the land or water and reduces the shock on landing. There are five common types—boat type, float type, skid type. wheel type, and ski type. (Amphibian may be a combination of the float or boat type with wheels or skis.) landing gear, retractable, is a landing gear so designed that it can be withdrawn into the body or wings of an air- plane to secure better streamline efficiency while in flight. *landing speed—See SPEED, LANDING. NJ № № º ><！ - NJ ●zººwwww zzzzZ)|× -******»^ , ， , º > _^•••••••••• •/º -Zwee’-º-º zoº, _Zzzzzz.&T rayev svº ºbavezavezzº*ae * 19 quoſq xſo eļļV 334 In A aqq uo uusqueq03 IN 1e90 3uſpueT º[qeņoeņ3}} →ų L * * zvszaw&zºzw zawszºwº-wsc^ ^ `Jº&sº ºwew z vzveza/ rºzwo-Zºzw zx/zy Zso??！~" NJ|-zosz， zw zxzxz ºzy. ！~~ d’aºÁZA4A// sozzº szºrszwazº /zzasz zſºzaeus，/ ſięºway-Z vzws， 2&sº/ 2， »^f±_°~ . {_^（~） ^>7------^~） . ^ Lº^ * wº Ž Azzy//Zzy Zez Z2&7:2 24.4%2 ZZ ceaſzze 2- 227,77x 2- ZAZ Ze/24% The Tricycle Landing Gear on the Douglas DC-4. —T T- ~--–- ==E====E- ===#| ſ== –– ºlº º - * º ºilſ: lºſſ º: #|| #|*::::: º-ſ, " : º …' Ža/ae goee s sz-zerºo f AZAA /// cao se/7 acs/7/ory Azesz-s // 2&A=ssez’ ** zzazz//za eae& a' Ž2'szezszczy- .* a/~ 7///E A-Z/7/2" /5 2 * <<>//722 &. … T A 4/76/ /ZAZ2//y zºzºwa& A Typical Wing with a Fowler Flap. a y A/A or Aºs/7/O/Y }_AN landing (speed)—See SPEED LANDING. landing (stall) usually applies to a seaplane landing at ap- proximately stalling speed with the tail extremely low. This represents an emergency landing with a landplane, although all three-point landings are semi-stall landings. *landing T-A large symbol shaped like a capital T which is laid out on a landing field or on the top of a building to guide operators of aircraft in landing and taking off. landing (three point)—A landing in which the wheels and tail wheel or skid contact the ground at the same time. This occurs when the longitudinal axis of the airplane is at the landing angle with respect to the ground. landing (two point)—A landing in which the wheels only touch the ground, the tail wheel or skid remaining off the ground until most of the forward speed is lost. *landing wire—See WIRE, LANDING. *landplane—An airplane designed to rise from and alight on the land. lateral means crosswise. The lateral dimension of a wing is the span. - lateral axis—See AXIS, LATERAL. lathe is a machine designed to rotate the work to be ma- chined so that metal may be removed from a circum- ference by a cutting tool. latitude—The measurement in degrees north or south of the equator. latitude (difference of)—The angular or degree difference between the latitudes of two places measured on a me- ridian. latitudes, horse—See HORSE LATITUDEs. latitude (parallel of)—The small circles on the earth's sur- face whose planes are parallel to the plane of the equator. launching crew is the crew of men who manipulate the shock cord in launching gliders. “leading edge—The foremost edge of an airfoil or propeller blade. Also called "entering edge." “leak detector—An instrument which detects the presence of hydrogen and other light gases in the air, and which can be adapted to find leaks in a container inflated with such a gas. leather is used for cushions, upholstery, engine-bed pads and small finishing details. leeway is the lateral drift of an aircraft to leeward of its course. Leeward means away from the wind or the di- rection toward which the wind blows. Leeway is the allowance necessary to counteract for the lateral drift. “left-hand engine—See ENGINE, LEFT-HAND. “left-side (engine)—That side which, to an observer look- ing from the antipropeller end toward the propeller end, lies on the left-hand side. legend—The explanation of conventional signs or symbols on a map or chart. Lenz's Law states that the direction of an induced current, H_EV in electromagnetic induction, opposes the motion produc- ind it. le: is a bar by means of which a force applied at one point will do work at another point through the medium of a third point of rest or support (fulcrum) of the bar. The fulcrum may or may not be located between the ap- plied force and the point where the work is done. *lift—That component of the total air force on an aircraft or airfoil which is perpendicular to the relative wind and in the plane of symmetry. It must be specified whether this applies to a complete aircraft or to parts thereof. In the case of an airship, this is often called “dynamic lift.” Its symbol is L. The “absolute lift coefficient" is CL as defined by the equation L CL = qS in which L is the lift, q is the impact pressure (=%pV’) and S is the effective area of surface upon which the air force acts. e lift coefficient is the lift in pounds that may be derived from one square foot of wing area traveling at a speed of one mile per hour at a given angle of attack. This leads to the formula L=KyAV' where L=lift in pounds Ky=coefficient of lift A=wing area in square feet V*=velocity squared. lift-drag ratio—The ratio of lift to drag. The lift-drag ratio varies with the angle of attack. Its value is greatest at the optimum angle of incidence. *lift (of a gas)—The difference of density of air and the gas. Both supposed to be under the same conditions of pressure, temperature, etc. *lift, dynamic—The lift impressed on an aerostat by aero- dynamic forces. *lift, gross (airship)—The lift obtained from a volume of buoyant gas equal to the nominal gas capacity of the air- craft. Obtained by multiplying the nominal gas capacity by the lift per unit volume of the gas used for inflation. lift, margin of-The measured ability of an airplane to gain altitude in a given time under given atmospheric condi- tions. *lift, static (aerostat)—The resultant upward force on an aerostat at rest obtained by multiplying the actual vol- ume of the air displaced by the density of the air and subtracting the weight of the contained gas. (The vol- ume of the air displaced, multiplied by the difference of density of the air and the contained gas.) *lift, useful (airship)—The lift available for carrying fuel, and oil, passengers, cargo, food and drinking water, guns, ammunition, and bombs. Usually determined by deducting from the gross lift all fixed weight; certain allowances of ballast, fuel, and oil; water; spares and The Forces acting on an Airplane resolved into a Parallelogram of Forces (Brewster Fighter). // = 7%%.57 A22CA = DA"- 242/7& Azºº.cA: VA = //A 7" A 2&ra = WA = Wa/a://7 2-43&42deal is sºlº 3rºve/4/zsz. £ºs. . Sºs --> º:ºjºs -ºſz sººº-º-º-tee- rºº 7t *::::::::::::::ss.x=Fº - & j <^774&yee. Azzzzzezzzzz/72./ Azz Aze 774 coaszczzoa. A AZZ-Fºyzz»e. Airplane Tail Surfaces (Northrop U.S. Coast Guard). º A/A-7- ii M/A/47//7" Že 7zz Aoeces Aſea aſor coaszoeae o zo. 7&as Azgazze The Forces acting on an Airplane (Curtiss SBC-4). 4/o Aºzze zo: Wavºr ºzoave ſ ſ / / Dy Lic- —#– l E 4% a'azz/o .# AEAy7/2. As AF//2/2/_Arºyeſ The Lift of a Wing alone, and the Lift when it is At- tached to the Airplane (Stinson). LIF tools; crew and equipment. No standard has as yet been established. *lift wire—See WIRE, LIFT. lightening rib-See RIB, FORM. limit, elastic—See ELASTIC LIMIT. line, air—See AIR LINE. *line, bow-steadying—See LINE, YAW. line, datum—See DATUM LINE. *line, grab–See LINE, HANDLING, and ROPE, DRAG. *line, handling—A line attached along the side of an airship for use in maneuvering near and on the ground. Some- times called "grab line." *line, main hauling—Same as MAIN MOORING LINE. *line, main mooring—The line dropped from the bow of an airship to be coupled to the mast main mooring line. *line, mast bow-steadying—See LINE, MAST YAW. *line, mast main hauling—Same as MAST MAIN MOORING LINE. *line, mast main mooring—A line led from the main winch of a mooring mast through the mooring attachment at the top of the mast and carried out to a point on the ground well to leeward of the mast. The airship's main mooring line is attached to this line and the airship is hauled to the mast by means of the joined lines. Some- times called "ground wire"—British. *line, mast yaw—One of the lines led from a winch at the base of the mooring mast through snatch blocks and car- ried out to leeward of the mast. The airship's yaw lines are attached to these lines. The snatch blocks are fixed to anchorages selected so that the joined lines tend to keep the airship into the wind and prevent her over-riding the mast. These lines are also sometimes called "mast yaw guys" or “mast bow-steadying lines." *line, mooring—A line attached near the bow of an airship for securing it to the ground or to a mooring mast. *line, nose-steadying — See LINE, YAW, which is to be pre- ferred. *line, sandbag—A rope extending along the line of suspen- sion ropes or bridles of a kite balloon to which are §: the sandbags used in mooring the balloon. The rpose is to prevent wear on the suspension cordage. line squall—See SQUALL, LINE. *lines, control—The lines of wire and/or stranded cable leading from the control car or compartment to the vari- ous parts of an airship and operating (either through mechanisms or directly) the rudders, valves, etc., which control the speed, altitude, etc., of the airship. lines of force are the lines along which a magnetic influence exerts its force or effect. *line, suspension—A line either of cordage or metal, which supports the weight attached to the envelope of a balloon or airship. *line, yaw—A line dropped from the bow of an airship; when mooring to the mast, to act as a steadying line to prevent yawing and overriding the mast. Also called “bow- LIT steadying line" or "yaw guy." ("Side guy wire"— British.) liter (metric system) equals 61.02 cubic inches or a little more than a quart. lithosphere—The landed parts of the earth. *load: dead—See WEIGHT, EMPTY. full—Weight empty plus useful load. Also called “gross weight." pay—That part of the useful load from which revenue is derived, viz., passengers and freight. useful—The crew and passengers, oil, and fuel, ballast other than emergency, ordnance, and portable equip- ment. *load, basic—The load of an aircraft when it is at rest or in a condition of unaccelerated rectilinear flight. (For pur- poses of stress analysis.) *load, dynamic—Any load due to accelerations of an air- craft, and therefore proportional to its mass. *load factor—The ratio of any specified load on a member to the corresponding basic load. Generally applied to the ratio of the breaking load to a basic load. *load ring—See RING, CONCENTRATION. “loading, power — The gross weight of an airplane, fully ‘loaded, divided by the normal brake horsepower of the engine computed for air of standard density unless other- wise stated. *loading, wing — The gross weight of an airplane, fully loaded, divided by the area of the supporting surface. The area used in computing the wing loading should in- clude ailerons, but not the stabilizer and elevators. “lobe—An air or gas inflated bag fitted at the stern of a kite balloon and acting as a fin or stabilizer to give it aerody- namic stability. lobe (cam)—The raised portions on the contour of a cam which cause movement of the cam followers. Local Apparent Time (L. A. T.) signifies sun time meas- ured by the apparent sun at the place where the observer may be. Local Apparent Time plus west longitude equals Greenwich Apparent Time. Local Apparent Time minus east longitude equals Green- wich Apparent Time. Local Mean Time (L. M. T.) or Mean Solar Time (M. S. T.) signifies clock time measured by the mean sun at place where observer may be. Local Mean Time minus east longitude equals Greenwich Mean Time. Local Mean Time plus west longitude equals Greenwich Mean Time. lodestone is a stone called magnetite, largely oxide of iron, which acts like any magnetic needle in seeking the North Pole and attracting other pieces of metal. *logarithmic decrement—The natural logarithm of the ratio of two successive amplitudes in a damped harmonic mo- }_OG tion. It is equal to the product AT, where A is the coeffi- cient appearing in the damping factor of damped harmonic motion and T is the period of the motion. log books—Books for recording the pilot's record of each flight, the engine record, and the plane record. “longeron—A fore-and-aft member of the framing of an air- plane fuselage or nacelle, usually continuous across a number of points of support. longitude—The measurement in degrees East or West from the prime or zero meridian at Greenwich, England. longitude, degree of See DEGREE OF LONGITUDE. longitude (difference of)—The arc of the equator between the meridians of two places. longitudinal axis—See AXIS, LONGITUDINAL. }longitudinal dihedral angle — See ANGLE, LONGITUDINAL DIHEDRAL. *longitudinal, intermediate — An intermediate longitudinal strength member of a rigid airship, which lies between two adjacent main longitudinals and is generally of lighter weight and/or smaller dimension than the main longi- tudinals. *longitudinal, main—A main longitudinal strength member, of a rigid airship, which connects the various transverse frames. loom——The web sections of wing ribs. “loop, mooring—See LOOP, SANDBAG. loops involve a zoom, which is over past the vertical, to be followed by a moment of inverted flight in the opposite direction and a dive out of the inverted position to a nor- mal recovery in the direction of original flight. Altitude may be maintained, gained, or lost depending upon the execution of this maneuver and the power of the engine. loop (ground)—Turning a plane quickly about the vertical axis while running on the ground by means of hard rudder action. This is an emergency maneuver to prevent a colli- sion with other objects or persons. loop (outside) is a simple maneuver, but it imposes excessive strains on both the pilot and plane. The plane is dived beyond a vertical dive and so on around until it has been forced up and over to a normal flight position in the direc- tion of original flight. * loop, safety—A loop formed in a rip cord and attached to a securing patch by a breakable cord or a spring clip. It may be formed either inside the envelope and close to the rip panel or outside the envelope near the gland by which the rip cord passes through the envelope. Before the rip panel can be "pulled" the breakable cord must be broken or the clip opened. Accidental “pulling" is thus made unlikely, as the weight of the cord is easily carried by the breakable cord or spring clip. "loop, sandbag—A system of cordage loops on the envelope of a balloon for suspending sandbags. See also LINE, SA NI)PA(;. loop (upside down) is a loop started from a position of inverted flight and ending in the same position, having LOW followed the same path as that made by an outside loop. In both of the maneuvers the pilot hangs on the belt as a result of the centrifugal force which tends to throw him away from the plane. low (polar)—See POLAR LOWS. low pressure area—An area of low barometric pressure. Bad weather may be expected in such an area. lubber line—The fixed indication line on a compass case which is also on the longitudinal axis of the aircraft. lubrication is designed to prevent direct contact between the bearings and moving parts of machinery, thus reduc- ing or eliminating friction. machining is the machine (lathe, planer, boring mill, drill, shaper, grinder, etc.) finishing of objects and parts. magnet—A piece of material which attracts other magnetic materials, and which, when freely suspended, points to the earth's pole. magnet, permanent is a piece of material which, once mag- netized, retains its magnetism permanently. magnet, temporary is a magnet which retains its magnetism only while under the influence of a given magnetizing force. magnetic attraction is the force of attraction between two objects which are magnetized. This is perfectly true when a magnet attracts a piece of material, because the magnet first magnetizes the material and then opposite poles are mutually attractive. magnetic attraction (compass)—Deflection of the magnetic compass needle, caused by the presence of magnetic ma- terial in the airplane or immediate neighborhood of it. magnetic course—See COURSE, MAGNETIC. magnetic density is the closeness with which the lines of force are packed together in a magnetic field. Magnetic density is a measure of magnetic strength. magnetic field is that region surrounding a magnet which is occupied or permeated by lines of force. magnetic fields, attraction and repulsion of Magnetic fields of parallel conductors are mutually attractive if the cur- rent in both wires is flowing in the same direction, i. e., if both wires are either positive or negative with the mag- netic fields of force in the same direction. The fields are mutually repellent if the currents in the two conductors are flowing in opposite directions, i. e., if one conductor is positive and the other negative with the magnetic fields of force in opposite directions. magnetic flux is the total of lines of force permeating a mag- netic circuit. magnetic lines of force (direction) around a current-carry- ing conductor form a continuous cylindrical whirl in a clockwise direction when the current is flowing away from the observer. magnetic north—See NORTH (MAGNETIC). magnetic poles — The positive and negative poles of the earth, considered as a magnet. The magnetic poles are at a considerable distance from the geographical poles. '}\n'sıną p33ų>{OOT 99-aſ sduo O uſV ’S ‘n &sa=/ory oe &=37 veze cºry $ \ y *-m-- / ...Agº T---- _-T T-a- Af —º I —T p -> —3 — *- —E -º-> → - ~T –º Award/cf/CA/ Tº –- -, - –-- ~T 7/oay J *: *— º __4 aucra oaw —º | ------- * º T- – º –º —ºs --> —ºe Tº" --> —- —- —— —- -- —º –º º P" -> --—º- ——es. - +- —º *—--sº IT --> – — —- *--> -—º. —iº — 2. T- | Æezz/oav ca’ 4.ogves 7/242&s- Jayaſ & A77° 7A/20/7 * * f *~. _* ---. A .* *~ ...” sº 4/~avoazezęzs-" /* means of Manometers. 24/ºese -szzare 2- ºrzoz ~~ < —º __ºf —º 2 o O 22e/e7ce CAE A-7/2/Yo/v7e.77 EAE- o” O O X | r y ‘A/4// A 2&3.54/25 /May//o/757&as Area Azzso 2/342 72 Azeaxarea 7//e /*45-5-54/4°A: D/ 57 A/A4/7/C/y O/Y 7 AyAF A-Z 5A-Z/7&AE, A//7c. A Z.A.A.F.5, AZ.5 /425ZZ /5 APZZ «2/Y722/ Ja'47A/7CAF.5 5/////, /742 72 7//EFAZAP7//oz) zº/E/2/c ZAFA) /AEA2A3. WAWAR’ Ar’&SSA/42/E AZAFAZ-54/42AEAZAFay7.5 oaz Apay /2/42/Exº~ A2ZZ9 /Ay /7/AF ZX57.25 4:AZ//y/77%d/Y O/C Ava AP 5_5 Z/4-A5 ZX57.2/45Z,’7”/o/Y -> * A, Typical Venturi Tube showing the Pressures by A. oxee 7&a= ºv/r/ð 34/2a-arce. 72/5 / 5 Aazaazz /av Zay/Yº- &/7 7//E ZE 5/g^y 2/F 7AA. Wo%2-5a-223 Azºv.z Az/as. Method of Connecting a Manometric System to an Airfoil. *** , Z2nz Azerszeº, B. A 24/azzo NIAG magnetic saturation results in a non-magnetized object when the magnetizing force applied to produce magneti- zation is sufficiently great to completely rearrange the molecules of the object. magnetic variation—See VARIATION, MAGNETIC. magnetism, first law of Like poles repel each other. Un- like poles attract each other. magnetism, residual is the relatively small amount of mag- netism which remains in an object after the magnetizing force has been withdrawn. magneto—An electrical device used for the production and distribution of electrical pressure or potential. A rotating armature produces a current of low value in a primary winding (coil). This primary current is elevated to high potential in a secondary or high tension coil. magneto, booster—See BOOSTER MAGNETO. magneto speed of rotation—The frequency of spark produc- tion in degrees of magneto rotation, times the number of cylinders, divided by 720° (for 4 cycle engine) (360° for 2 cycle engine). magnets (compensating)—Small magnets in a compass used for correction of deviation. magnitude (of stars) is a measure of the brightness of stars. *main hauling line—See LINE, MAIN MOORING. main jet (carburetor) is the main jet or nozzle which dis- charges liquid fuel into the Venturi chamber or barrel. main longitudinal—See LONGITUDINAL, MAIN. main mooring line—See LINE, MAIN MOORING. main mooring line, mast—See LINE, MAST MAIN MOORING. main shear wire—See WIRE (AIRSHIP), MAIN SHEAR. main supporting surface—See SURFACE, MAIN SUPPORTING. main transverse—See TRANSVERSE, MAIN. maneuverability—That quality in an aircraft which makes it possible for the pilot to change its attitude rapidly. *maneuvering valve—See VALVE, MANEUVERING. “maneuvering-valve hood—See HOOD, MANEUVERING-VALVE. *manhole, appendix—An appendix of large diameter and usually rather short. It is used more for access than for inflation or deflation. *manifold, inflation—A metal or fabric connection with nu- merous inlets which permits the passage of gas at the same time from a number of sources (either cylinders or gas holders) to the main inflation tube. *manometer pressure—See PRESSURE, MANOMETER (AEROSTAT). *manometer-tube gland—See GLAND, MANOMETER-TUBE. mantissa is the decimal places in a logarithm as shown in logarithmic tables. See CHARACTERISTIC. manual means any process or operation carried on by hand or executed by a person in contrast to automatic or ma- chine operation or control. Processes carried out with hand tools are classed as manual operations. map—A representation of a portion of the earth's surface on a flat surface, usually showing more land than water. maple has excellent qualities in strength and reliability for . MAP very small wood detail requiring unusual resisting powers, like the block connecting ribs across a spar. map, profile—See PROFILE MAP. mass of an object is the weight divided by the acceleration of gravity (32.174). mass—The mass of a body is a measure of the quantity of material in it. *mast bow-steadying line—See LINES, MAST YAW. “mast main hauling line—See LINE, MAST MAIN MOORING. *mast main mooring line—See LINE, MAST MAIN MOORING. * mast, mooring—A mast or tower at the top of which there is mounted a fitting, so that the bow of an airship may be secured. It is usually provided with a ladder or staircase and a platform at the top, so that crew and passengers may enter or leave the airship, and also with piping for the supply of fuel, gas, and water. Sometimes called “mooring tower." *mast yaw line—See LINE, MAST YAW. mean is a word which, under practically all circumstances, is synonymous with the word average, such as mean (average) effective pressure. mean day is the period of time between two successive transits of the mean sun over the same meridian. mean effective pressure (internal combustion engine)—The average working pressure on the piston during the cycle. mean noon is the instant when the mean sun's hour circle coincides with the meridian. mean Sun—A fictitious sun assumed to move in the equinoc- tial or celestial equator with a uniform velocity that equals the mean velocity of the true sun in the ecliptic. mean time is the hour angle of the mean sun. mercator projection—A projection from the center of the earth of portions of the earth's surface onto a cylinder wrapped around the earth. mechanical convection—See CONVECTION, MECHANICAL. meridians — Great circles on the earth's surface passing through the North and South Poles. meridian (of celestial sphere) is half of a great circle extend- ing from one celestial pole to the other and is similar to a meridian on the earth. meridian (prime or zero)—The meridian passing through Greenwich, England, and from which longitude is meas- ured East or West. metal (base)—Metal to be welded. Usually two pieces of identical metal. metal (ferrous)—Any metal derived from an iron base. metal (filler)—The material, usually in rod form, which has been melted and deposited in making the weld. Filler metal is deposited by the welding rod in gas welding and by the electrode in electric arc welding. meteorology—The science which treats of the condition of the atmosphere, its changes in condition, and the causes therefor. meteorological elements — 1–Temperature, 2–Pressure, 3– Wind direction and velocity, 4–Humidity, 5–Sunshine, Wºwz, &evv &zezz. CºzzAPA42 A/A-A/e7% 4 is 4/2. Coozed & Gººſe Ž sc/eazycz’s S. £ºft, | - | Tº ſ - ºv * ... iśl f \ ſº / \ |- . Thiſ f W . . ; T - Lºº Hºlº º:---- sº º sº º-- . —- E---> -- - sº º - J § M sº 3-M-Aza/voco&E & Zazzaſe i A4 A/ezzz AZsézaee / Zºe A* f / as? Ahzezoer / - fés 5. 24 4xaºayzays A‘Zze=7 / \ 14%aº Azaze Jºzéezºeza. Zºzz A4/eaz AZZ arezzºz. oxzzzzezzozae- \ / A Af r <2/zzez Zaeae. SE. Pºrca, fºoeezzezi ž AZzz cºa/7/ze yea-way& ºv, 7A/ 2’ Azad Gaº’s 5//e A7/43/ºzoº/- 42&75/YZ2– C 727&A. AE, Aºzzaczzaz & //yº Azºo/v7 14///Yeº ºc 7" 7"o Yévé: Zaevo/ave Geeva, G. ar A//aye, 77/2 A Typical Low Winged Monoplane (Northrop Basic Trainer). - ... • AZZ areza, anozzycs.…az- A-Z/ZZ cap/y//ZAFV4:42 ºv//yo, 4. azezzº. A/a. */2 A syza/4/zAA’. Wrzº ---- / s7 EAEA 72/43/Axe 4×z/22732, ſ' 4,552.42 eydow Azºp Æ24: Mºyzzºe, AZ;45&/C ſ g devºo §, Aºp/al awa, ceece a Fayetave | || W/7// A/47&AW Coº A Typical Mid-wing Monoplane (North American O-47 U. S. Air Corps). AZY/wooz Az/44 carv7/ZAFVE2. A%zoep 5 sea -s tº ºrº- -º j 7/8/6% AA7&z/c-- 7 |– f : 3 / 4%ree-rrezy covereo 72/2 v - - - - - É - AZeesys \ --- 270/az Azz, kiſſ AVG Coo/.45/7 /ZoZºo<2 > 'ſ- + - / /7Zz67 era ///e6, | ,-Aſ&c. Aſ CºwlſarG. ." Aroor, ; : . E- - - - A. ! G-E /LDS) # = v → -- T. —in F - -IF =~7 sº-TV /– === Wºzzez.57&AZ /ø/ave A → - Zºº; /*ZAPA’ Zez/55 7%ae AZ.5&AWGAE Azaz/c Corzęe a covreć, Zºeze A/zkaz `ºzzo Zaa.ca/& aeae . Axeoaez 4.4542– A Typical High Winged Monoplane (Fokker). &reaczzaze-’ &aſ_ss/s Azazz cºvzze Pea- Azza—ºv/cº- sº Aºra Awczazeze ~ 1 /Zzz caa/7Zevée. Cºssas 4 a tº ºvº avº. C. | A257&azzazaz E &55/s---_ TZZeasaz, wavºr 4. - - * > / * - e / A. > –5547/- czaſzzérez. Cavaz-55/5 * //ez &ea=&2 ->eazz — carzzaree 244 Avog. \ % Afzezzazz c 4/4.55/5 The Basic Forms of Monoplane Wing Bracing. MET 6–Cloudiness, 7–Precipitation, 8–Visibility. meter equals 100 centimeters equals 39.37 inches. *meter, air-speed—See AIR-SPEED METER. *meter, ground-speed—See GROUND-SPEED METER. metering jet (carburetor) is an orifice of given size in the fuel passages of a carburetor designed to govern the flow of fuel. *meter, superheat—An instrument for measuring the differ- ence in temperature between the gas in a gas container of a lighter-than-air craft and the surrounding air. mill, boring—See BORING MILL. mineral oil (lubrication) is refined from the heavier hydro- carbons (residue) obtained by distilling off the gasoline, naphtha, and kerosene from crude petroleum. “minimum gliding angle—See ANGLE, MINIMUM GLIDING. “minimum speed—See SPEED, MINIMUM. mixture (fuel vapor)—The proportions by weight of fuel and air. modulus or coefficient of elasticity is the ratio between the stresses and the resulting deformations caused thereby for a given material. The symbol for modulus of elasticity is E and it equals the stress in pounds per square inch divided by the deformation per inch. Figures for E run into millions of pounds per square inch, because the de- formation is very small compared to the stress causing it. It has been frequently stated that a ratio is a number only (without denomination) and is true in this case, referring only to the stress applied and the unit area. moment of force about a point is the magnitude of the force times the distance of the force from the point measured at right angles to the direction in which the force acts. momentum—The product of the mass and the velocity of a body. *monocoque fuselage—See FUSELAGE, MONOCOQUE. *monoplane—An airplane which has but one main support- ing surface, sometimes divided into two parts by the fuselage. monsoon—A seasonal wind blowing landward in summer and seaward in winter. “mooring band—See BAND, MOORING. “mooring cone—See CONE, MOORING. “mooring-cone outrigger—See OUTRIGGER, MOORING-CONE. “mooring drag-See DRAG, MOORING. mooring harness—See HARNESS, MOORING. mooring line—See LINE, MOORING. mooring loop—See LOOP, SANDBAG. mooring mast—See MAST, MOORING. mooring ring—See RING, MOORING. mooring rope—See ROPE, MOORING. mooring, three-point—A system of mooring an airship. It consists primarily of three lines running from a mooring ring (or point) on the airship to three points on the ground. These points are usually at the vertices of an equilateral triangle. The lines may be secured to anchor- ¥ Y jºr Y ¥ Y Y MOO ages at the points, or run over snatch blocks and to equal- izing gear. The endeavor is to moor the airship in such a manner that the dynamic lift, due to the relative wind, shall keep the airship at a constant height from the ground. May be considered as a substitute for a mooring mast, usually an emergency substitute. “mooring tower—See MAST, MOORING. motion, uniform—See UNIFORM MOTION. motion, variable—See VARIABLE MOTION. motor, electric is a machine that transforms electric power into mechanical power by means of the pressure set up between the lines of force of a magnetic field and the field of force about the current-carrying windings of a rotating armature. motor-generator is an alternating current generator directly connected to and driven by a direct current motor. *multiplanes—An airplane with two or more main supporting surfaces placed one above another. mushing through is caused by attempting to maneuver an airplane by sheer control faster than the maneuverability of the particular airplane will permit. For example: at- tempting to pull out of a dive faster than the airplane can respond to the elevators. mutual inductance is the mutual interference of two mag- netic fields of force, but without actual contact. Mutual inductance of two coils can be obtained by moving a con- tinuous current coil in and out of the second coil, or making and breaking the current flow in one coil placed permanently inside of the other coil. “nacelle—An enclosed shelter for passengers or for a power plant. A nacelle is usually shorter than a fuselage, and does not carry the tail unit. nautical mile—6,080 feet. Also equals 1 minute of longitude at the equator. navigation radius—See RADIUS OF ACTION. needle valve (carburetor) is a simple valve device consist- ing of a needle point which fits into a beveled seat. The joint is a ground joint to make it gasoline-tight when closed. *net: free balloon—A rigging made of ropes and twine shaped to the upper surface of the envelope, which supports the weight of the basket, etc., and distributes the load over the entire upper surface of the envelope. gas-cell (rigid airship)—A netting of cord of small mesh which is intended to assist the fabric of the gas cells in transmitting gas force to a wire netting of coarser mesh and to the longitudinals, both being fitted between the longitudinals. It may be compared to the net of a free balloon. Sometimes called “gas-cell netting" or “cord netting.” inflation—A rectangular net of cordage used to restrain the envelope of a kite balloon or airship during inflation. Also applied to a free-balloon net designed to be re- moved after inflation. NET “netting cord—See NET, GAS CELL (RIGID AIRSHIP). *netting wire—See WIRE (AIRSHIP), NETTING. neutral lift line—A line taken through an airfoil in a for- ward direction relative to the direction of motion and starting from the trailing edge. If the attitude of the air- craft is such as to make the neutral lift line coincident with the direction of motion, then no lift will result—the reac- tion consisting solely of drag. Newton’s Laws of Motion: 1. If a body be in motion, it will move uniformly in a straight line until acted upon by some force. If at rest, it will remain at rest. -> 2. The rate of change of the quantity of motion (mo- mentum) is proportional to the force which causes it, and takes place in the direction of the straight line in which the force acts. If a body be acted upon by sev- eral forces, it will obey each as though the others did not exist, and this whether the body be at rest or in motion. 3. To every action there is opposed an equal and oppo- site reaction. nickel—An alloy used to toughen and strengthen steel. nomenclature of any subject is a term applied to the defini- tions of parts, uses, factors, and features which come under the subject heading. *nominal gas capacity—See CAPACITY, NOMINAL GAS. non-conductors (electrical)—Materials which do not con- duct, but rather hinder the passage of electricity. *non-rigid airship—See AIRSHIP, NoN-RIGID. noon—The apparent or solar time when the sun is directly above the observer's meridian. normal means perpendicular. A line is perpendicular to a curve or cylinder when it is perpendicular to a tangent to the curve or cylinder at a given point. north (compass)—The actual north point to which a com- pass needle points, due to errors caused by local magnetic attraction. north (magnetic) — Latitude 71° North, Longitude 96° West. The north pole which attracts a compass needle. Magnetic north and compass north are coincident when the deviation of a particular compass is zero. North Star (Polaris) is on an imaginary line drawn upward from the two stars in the bowl of the Big Dipper. Polaris is a fixed star which is nearly in line with the axis of the earth and, therefore, appears to be almost coincident with the celestial north pole. north (true)—The north extremity of the earth's axis of rotation. nose—The bow of an airplane; usually the front end of the fuselage or hull. * nose (airship)—Sometimes used for bow. * nose batten—See STIFFENER, BOW. *nose cap—See CAP, BOW, which is to be preferred. nose dive (spinning) is really causing the plane to roll about : NOS the longitudinal axis by using aileron control while a plane is diving straight downward. 3. "nose heavy—The condition of an airplane in normal flight when the distribution of forces is such that, if the longi- tudinal controls were released, the nose would drop. *nose-heavy (airship)—See BOW-HEAVY. "nose-steadying line—See LINE, YAW. nozzle, discharge—See DISCHARGE NOZZLE. “nozzle, pressure—An instrument which, in combination with a gauge, is used to measure the indicated speed of an air- craft relative to the air. It may be a Pitot-static or a Ven- turi tube, or a combination of a Pitot tube and a Venturi tube. numerator of a fraction is the top figure of a fraction which is to be divided by the denominator (figure under the bar). The bar in a fraction means division. “nurse balloon—See BALLOON, CONSTANT PRESSURE. "nursing tube—See TUBE, SUPPLY. oak is largely used for engine bed construction and the fab- rication of pontoons and boat hulls. "observation balloon—See BALLOON, OBSERVATION. "observation platform—See PLATFORM, OBSERVATION. obtuse angle—See ANGLE, OBTUSE. octant is an instrument similar to a sextant, but its range is 45° (one-eighth of a circle) whereas a sextant has a range of 60° (one-sixth of a circle). ohm-The unit of electrical resistance. Ohm's Law—Volts (E) = Amperes (I) × Resistance (R). oiled track is an oiled runway of wood or metal used to facilitate glider launching. oil, mineral—See MINERAL OIL. oil pump is a pump, usually of the gear type, used to circulate oil under pressure through hollow crankshafts, camshafts, accessory drives, etc. oil, vegetable—See vegETABLE oil. *optical altimeter—See ALTIMETER, OPTICAL. ordinates are the distances on the vertical axes of curve diagrams. orientation means the accurate understanding at all times of compass directions, wind direction, altitude and atti- tude of the aircraft. In stunting, it means to know the exact attitude of the aircraft at any moment of time. *ornithopter—A form of aircraft heavier than air, deriving its chief support and propelling force from flapping wings. orthogonal biplane—See BIPLANE, ORTHOGONAL. oscillation—A swinging backwards and forwards. The motion of a vibrating wire is a form of oscillation. "oscillation, phugoid—A long-period oscillation character- istic of the disturbed longitudinal motion of an aircraft. This is referred to when it is said that an aircraft "hunts." "oscillation, stable—An oscillation whose amplitude does not increase. "oscillation, unstable—An oscillation whose amplitude in- creases continuously until an attitude is reached from which there is no tendency to return toward the original OUT attitude, the motion becoming a steady divergence. *outer cover—See COVER, OUTER. “outrigger, mooring-cone — The member, usually tubular, which supports the mooring cone at the bow of the air- ship. Sometimes referred to as “mooring spindle." “over-all length—The distance from the extreme front to the extreme rear of an aircraft, including the propeller and the tail unit. “overhang—Used in two senses. (1) One-half of the differ- ence in span of any two main supporting surfaces of an airplane. The overhang is positive when the upper of the two main supporting surfaces has the larger span. (2) The distance from the outer strut attachment to the tip of the wings. “overhead suspension—See SUSPENSION, OVERHEAD. #overtaking—Definition—An overtaking aircraft is one ap- proaching another directly from behind or within 70° of that position, and no subsequent alteration of the bearing between the two shall make the overtaking aircraft a crossing aircraft within the meaning of these rules. overlap (power)—The amount which the power stroke of one cylinder overlaps the succeeding power stroke. overshoot a landing field means that the gliding angle car- ries the airplane too far over the field to make a landing within the limits of the field. oxygen (pure) is a colorless and odorless gas which sup- ports combustion to a high degree. It is this high com- bustion level which makes oxygen so valuable in the acetylene welding process. Oxygen is also used to main- tain carburetor mixtures at high altitudes and to supply the pilot with oxygen under the same circumstances. Oxygen comprises about 21% of the atmosphere. oxygen system—All supercharged airplanes that are to be used at an altitude of greater than 20,000 feet should be equipped with oxygen apparatus. The oxygen bottles are connected to a regulating valve by small copper tubes. From the regulating valve the oxygen goes through a coil in the radiator expansion tank, where it is heated and then goes to the pilot through a flexible tube with a mouthpiece at the end. When the pilot wishes to use oxygen he opens the regulating valve until he is getting as much through the tube as he requires. The heating coil is used to pre- vent water in the oxygen from freezing and clogging up the line, and to make the oxygen more pleasant to take. ozone is a colorless gas having a pungent odor similar to chlorine. “pancake, to-To level off an airplane at a greater altitude than normal in a landing, thus causing it to stall and to descend on a steeply inclined path with the wings at a very large angle of attack and without appreciable bank. *panel (aerostat)—The unit piece of fabric of which the envelope or outer cover of an aerostat is made. Panels may be assembled into sections, gores, or rings, according to the method of manufacture followed. In rigid airships the area bounded by two adjacent longitudinals and two PAN adjacent transverses is often referred to as a “panel." This is a structural panel and the expression is borrowed from structural engineers. *panel, rip—A strip of fabric inserted or fitted in the upper part of the envelope of a balloon or semirigid or nonrigid airship which is torn or ripped open when immediate deflation is desired. *panel (wing parts)—Where a wing surface comprises sev- eral units of construction, these units are designated as panels. parachute (attached type)—A parachute whose container is fastened directly to the aircraft, the aviator's harness being fastened to the parachute by a life line. When the aviator jumps (bails out) the parachute is pulled out of the container without any manual operation. The con- tainer remains with the aircraft. parachute (back pack) is the type of parachute pack which is so attached to the harness that it remains across the upper back, permitting complete freedom of movement in moving or climbing about aircraft. parachute (chest pack) is a parachute pack designed to fasten to the harness across the chest of the wearer. It is generally used in conjunction with a back pack for addi- tional safety in exhibition and training jumps. parachute (fabric) is generally a specially woven high- grade silk designed to withstand the great impact of air pressure when the parachute is opened at high speed under pressure. This fabric forms the canopy of the parachute. parachute (free type) is a parachute carried complete in one unit and is fastened directly to the harness of the aviator. parachute (harness) is an especially woven linen webbing harness with a tensile strength of approximately 3,000 pounds. The harness is adjustable to the wearer and reinforced on all metal parts. parachute (harness metal parts) are the snaps and adapter buckles used in securing the harness and adjusting it to the size of the wearer. Metal parts are made of chrome nickel steel with a tensile strength of 5,000 pounds, and are either galvanized or cadmium plated for protection against corrosion. parachute (lap pack) is the type of parachute pack which is so attached to the harness that the pack rests comfort- ably in the lap. This pack is especially adapted to ma- chine gunners and photographers. parachute (lower main lateral band) is a band of heavy silk tape sewed within the hem. parachute (main panel or gore) is a triangular piece of fabric between two shroud lines in the canopy. parachute (manually operated) is a free type parachute which is operated at will by the aviator (wearer) by a slight pull on a "pull ring," which is located in a readily accessible place on the harness. parachute (oscillation) or swinging from side to side can PAR be checked by pulling down on the shroud lines of the high side on each swing. parachute (pilot chute)—A miniature parachute attached to the apex of the main canopy (Irvin air chute) designed to lead the main canopy out of the pack when the "pull ring" is operated. parachute (quick connector type) (Irving Air Chute Co.) is a chest pack carried independently in the aircraft in such a convenient position that an aviator wearing the harness can snap the pack on quickly with two easily accessible snaps. parachute (rip cord)—A cord or wire usually encased in flexible tubing which leads from the pull ring to the pins which lock the pack. Pulling the ring allows the “rip cord" to release the locking pins, thereby releasing the canopy itself to the air. & parachute (seat pack) is the type of parachute pack which is so attached to the harness that it may be used as a cushion, relieving the aviator of all bulk and weight. parachute (section) is a part of one of the main panels. parachute (service type) is a 24-foot parachute prescribed for service operations in the military branches of the government, air mail operations, etc. parachute (shroud lines) are usually silk cords of about 400 pounds tensile strength which are continuous from their point of attachment on one side of the harness, pass- ing through and over the top of the canopy to the other side of the harness. The entire length should be free from knots and splices. parachute (side slipping) is accomplished by pulling down a group of shroud lines on the side facing the direction in which it is desired to slip. This maneuver is advan- tageous in avoiding water and other landing hazards. Too pronounced a side slip should be avoided. Side slip- ping should be avoided close to the ground. parachute (skirt) is the outer rim of the main canopy where the hem occurs. parachute (sub-lateral bands) are the reinforced seams where the bias sections of a main panel are joined. parachute (upper main lateral band) is a double layer of heavy silk tape sewed to the main canopy at the base of the vent at the apex. parachute (ventage) is secured by the porous weave of the canopy fabric and by a vent hole at the apex of the canopy. parallax is the difference in angular altitude of a celestial body as measured from the center of the earth and the ob- server's point on the surface of the earth. Parallax varies from zero at the zenith to its greatest magnitude when the observed body is on the horizon. parallelogram—A four-sided figure whose opposite sides are equal in length and parallel. Used as a parallelogram of velocities to calculate drift and ground speed. parallel rulers—Two rulers or straight edges so joined by pivoted bars that the edges remain parallel, no matter PAR how far apart the edges may be. para-magnetic substances are only feebly magnetic. *parasite resistance—See DRAG. "patch—A strengthened or reinforced flap or fabric of special shape and construction, which is cemented to the envelope or gas cell. It usually forms an anchor by which some portion of the structure may be attached to the envelope, or by which the positioning lines controlling the gas cell may be attached to the cell. "patch, chafing—A patch of fabric secured to the envelope of an aerostat to protect it from abrasion. "patch, channel—A channel-shaped fabric-fitting secured to the envelope of an aerostat to allow a rod or spar to be laced to the envelope. "patch, finger—A special form of patch having extensions or "fingers" extending out from the central portion. The "fingers" may be of tape, frayed out rope, or fabric. Their function is to distribute the load more widely to the fabric of the envelope or gas cells. "patch, suspension—A patch, secured to the envelope or to a gas cell of an aerostat, to which a suspension line may be attached. path, flight—See FLIGHT PATH. *pay load—See LOAD, PAY. “pendant, sighting—A vertical wire on center line and for- ward of the control car of an airship, used as a mark in steering, to assist in determining wind direction. "performance testing—See TESTING, PERFORMANCE. *period—The time taken for a complete oscillation. permanent magnet—See MAGNET, PERMANENT. "permeability—The measure of the rate of diffusion of gas through intact balloon fabric; usually expressed in liters of hydrogen per square meter of fabric per 24 hours, under standard conditions of pressure and temperature. permeability is the ability of any substance to conduct mag- netic lines of force and also the degree to which any sub- stance is susceptible to magnetization. * phugoid oscillation—See OSCILLATION, PHUGOID. “pigmented dope—See DOPE (PIGMENTED). "pilot—An operator of aircraft. This term is applied regard- less of the sex of the operator. pilotage—See AIR PILOTAGE. "pilot balloon—See BALLOON, PILOT. pin, knuckle—See KNUCKLE PIN. pin center—The center of pin in fittings from which meas- urements are usually taken for wire and strut lengths. pinion gear—See GEAR, PINION. piston—The sliding unit in a cylinder to which motion is imparted by the expansion of the hot gases. piston displacement—See DISPLACEMENT (CUBIC PISTON). piston displacement equals radius X radius X 3.1416 × stroke. All measurements in inches give cubic inch dis- placement. piston pin–A round shaft used in the pin bearing connection Piston Travel Chart showing Degrees of Piston Travel as Related to Degrees of Angular Potation of the Crankshaft. w)St. § S. § s E. .#— |- * —l - J Cross-Section of an Aircraft Engine Piston, and Piston Ring. PIS between the piston and connecting rod. piston ring—Concentric rings inserted in grooves cut in the wall of a piston to hold compression (upper rings), and to prevent the passage of too much oil (lower rings) to the combustion chamber. *pitch, angle of See ANGLE OF PITCH. *pitch indicator—See INDICATOR, PITCH. *pitch of a propeller: effective—The distance which an aircraft advances along its flight path for one revolution of the propeller. Its symbol is pe. geometrical—The distance which an element of a pro- peller would advance in one revolution, if it were mov- ing along a helix of slope equal to its blade angle. mean geometrical—The mean of the geometrical pitches of the several elements. Its symbol is pe. standard—The geometrical pitch taken at two-thirds of the radius. Also called “nominal pitch.” Its symbol is S • zero thrust—The distance which a propeller would have to advance in one revolution in order that there might be no thrust. Also called “experimental mean pitch.” Its symbol is Py. zero torque—The distance which a propeller would have to advance in one revolution in order that the torque might be zero. Its symbol is Pa. “pitch ratio—The ratio of the pitch (geometrical, unless oth- erwise stated) to the diameter pyL). *pitch speed—The product of the mean geometrical pitch by the number of revolutions of the propeller in unit time— i. e., the speed the aircraft would make if there were no slip. Pitot bomb is a wind vane device carrying a Pitot tube which is suspended on a cable below an airplane to secure land- ing speed data which is not influenced by air disturbances about the airplane. *Pitot tube—A cylindrical tube with an open end which is pointed upstream (i. e., so that the air meets the instru- ment head-on or is met head-on by the instrument). When the aircraft is flying less than about 200 miles per hour, the instrument measures the impact pressure. When used on aircraft, it is usually associated either with a closed coaxial tube surrounding it or with a closed tube placed near it and parallel to it, the combination being termed a Pitot-static tube. The associated tube has per- forations in its side so that it is subjected to static pressure, as distinct from impact pressure. The speed of the fluid can be determined from the difference between the impact pressure and the static pressure as read by a suitable gauge. In common terminology the Pitot-static combina- tion, as above, is often termed simply a Pitot tube or Pitot. Pitot-static tube—A combination of two tubes, the Pitot tube to receive impact pressure and the static tube to receive static pressure. Used in conjunction with the air-speed PLA indicator. plane, soaring—See SOARING PLANE. planetary winds—The general or primary circulation of the atmosphere. planer (metal) is a machine designed to plane or surface metal parts. The tool is held on a cross beam and the bed of the planer moves back and forth carrying the work past the tool. planer (wood) is a flat bed machine which surfaces the flat side of a board by means of a high speed rotating cutter which surfaces the full board width at one time. planiform is the vertical projection of a wing surface, show- ing its tapered or rectangular shape, and the wing tip shapes, etc. plain view drawing shows the true shape of an object as viewed from the top. *platform, observation—A platform or small deck fitted on the top of an airship and used as a post for a lookout and defense or as a place from which to make observations used in navigating the airship. platinum is a metal used (platinum about 75%) in platinum alloy for contact breaker points in magnetos. Platinum is an excellent conductor of electricity, but is too soft for breaker points unless alloyed with some hardening agent. plotting—The process of constructing graphically on paper, directions, distances, courses, engine performances, etc. *plywood—A product formed by gluing together two or more layers of veneer. The alternate plies are usually placed with grain at right angles to the adjacent plies. polar lows—Areas of low pressure in the vicinity of the North and South Poles. polar projection—The projection of a portion of the earth's surface onto a flat plate, tangent to the earth at one pole lºans of projection lines radiating from the opposite pole. polar triangle—Triangle formed by the arcs of three (3) great circles. poles (geographical)—The extremities of the earth's axis of rotation. polyconic projection—The projection of a portion of the earth's surface onto a series of cones set down on the earth and tangent to parallels of latitude. Radial projec- tion lines are from the center of the earth. The projected strips of the cones, when developed or unrolled, cannot be matched perfectly, and so the finished map or chart has some distortion, especially near the edges. polymeter — An instrument used to register relative and absolute humidities, the dewpoint and temperature. *pontoon (now obsolete)—See FLOAT. poppet valve—See VALVE, POPPET. - porpoise—A series of bounces when making a rough land- ing, especially with a seaplane. position of a heavenly body is completely defined by its alti- tude and bearing"relative to the observer. POU pour test indicates the lowest temperature at which a given oil will pour or flow. power is a measure of the rate of doing work. The time ele- ment is always involved in a consideration of power. *power loading—See LOADING, POWER. power, margin of The available quantity of power above that necessary to maintain horizontal flight at the optimum angle. power overlap—See OVERLAP (POWER). precipitation—The fall of condensed moisture in the form of rain, snow or hail. Hail and snow are particles of frozen moisture, making a solid precipitate. press fit—See FIT, PRESS. “pressure alarm—See ALARM, GAS-CELL. pressure, atmospheric—See ATMOSPHERIC PRESSURE. “pressure, dynamic—See DYNAMIC (OR IMPACT) PRESSURE. “pressure flap—See FLAP, PRESSURE. pressure gradient—The change in barometric pressure over a given distance in a given time, indicating the severity of coming storms. “pressure height—See HEIGHT, PRESSURE. * pressure, manometer (aerostat)—The excess of pressure inside the envelope of an aerostat over the atmospheric pressure at a standard reference point. The point of ref- erence for the excess of pressure is usually the bottom of the envelope or gas cell for airships and the level of the basket for kite balloons. pressure nozzle—See NOzzle, PRESSURE. pressure-relief vent—See VENT, PRESSURE-RELIEF. pressure tube—See TUBE, PRESSURE. pressure-tube gland—See GLAND, MANOMETER-TUBE. prime meridian—See MERIDIAN, PRIME OR ZERO. primers are usually small pumping devices used to squirt raw gasoline into the intake passages or cylinders to facilitate starting. “profile—See AIRFOIL SECTION (or PROFILE). “profile drag—See DRAG. profile map—Profiles are used to show outline in vertical projection or cross-section. Therefore a profile map shows the outline of country in a vertical cross-section of alti- tude of points above a reference line, usually sea level. Directions do not appear on this map except as printed notations. - projection, gnomonic—See GNOMONIC PROJECTION. projection, polar—See POLAR PROJECTION. projection, polyconic—See POLYCONIC PROJECTION. “proofing—Material incorporated in the fabric of an aerostat at the time of manufacture to increase its resistance to the weather and/or to prevent the passage of gas (or decrease its permeability). “propaganda balloon—See BALLOON, PROPAGANDA. propeller—A surface so shaped that its rotation about an axis produces a force (thrust) in the direction of its axis. Yºr Yºr Yºr Y PRO * propeller: adjustable pitch — A propeller whose blades are so at- tached to the hub that they may be set to any desired pitch when the propeller is stationary. controllable pitch or variable pitch—-A propeller whose blades are so mounted that they may be turned about their axis to any desired pitch while the propeller is in rotation. “propeller area, projected—The total area in the plane per- pendicular to the propeller shaft swept by the propeller, excepting the portion covered by the boss and that swept by the root of the blade. This portion is usually taken as extending 0.2 of the maximum radius from the axis of the shaft. “propeller blade — See BLADE FACE; BLADE BACK, BLADE-WIDTH RATIO. * propeller-blade angle—See ANGLE, PROPELLER-BLADE. * propeller-blade area—The area of the blade face, exclusive of the boss and the root, i. e., of a portion which is usually taken as extending 0.2 of the maximum radius from the axis of the shaft. “propeller boss—The central portion of a propeller in which the hub is formed or mounted. "propeller-camber ratio—The ratio of the maximum thickness of a propeller section to its chord. “propeller-disk area, total—The total area swept by a pro- peller, i.e., the area of a circle having a diameter equal to the propeller diameter. "propeller efficiency—The ratio of thrust power to power input of a propeller. Its symbol is m. propeller etching—See ETCHING, PROPELLER. "propeller hub—The metal fitting inserted or incorporated in or with a propeller for the purpose of mounting it on the propeller or engine shaft. "propeller interference — The amount by which the torque and thrust of a propeller are changed by the modification of the air flow in the slip stream produced by bodies placed near the propeller, such as engine, radiator, etc. ‘propeller-load curve — A curve representing the engine power necessary to drive any given propeller at various speeds. The power required varies approximately as the cube of the speed in R. P. M., provided the ratio rèmains constant. “propeller pitch—See PITCH OF A PROPELLER. "propeller, pusher—A propeller mounted to the rear of the engine or propeller shaft. (It is usually behind the wing cell or nacelle.) ‘propeller rake—The mean angle which the line joining the centroids of the sections of a propeller blade makes with a plane perpendicular to the axis. “propeller reinforcing girder — See GIRDER, PROPELLER REIN- FORCING. V ND 3} sº assº sº. § ºf T--—ºr t § § R N § § S N S § § /~~~~~~ N 5Z//* 57.276/74t § § -º- .N. - $ | § § § § § § § 2-Azeeezzee- § R | Si | W__ ––––––– —t-- __-* /.../ez, sz /> /*eozz/ce o ºx caſe 3/a/~ & Azaws.s 2/F area ºvá'ſcº /5 area cºzzo zeory za ea //vate Aased //Y z7.5 /-Z2/v Vazoc/7"Y. 72/4: AZAZ2///v7r 2/F 7/yaz’s 7 / 5 caſ/.ca/ZAZ725.2 A, 5 A/ AZ//waz /o/Y 2/F 7//AF AZAZ 5.5 of Az//a a Asarc.77 EZ2 & 42c/Y / AFat Jaco/v42 Araya 7"AA" Prº/A/- Ay 7/o/y Zez’azzez, cay 7 A/AF Zayaaa’ez /~EZ oc/7 Y. Zºe Pºezoc/- 7"Y 2/c 7://e 52 /a 57a &Azaz / 5 A//a://e-A’ 72/7/Y 7A/AC //Y4242 ºz A-Z oar. A Diagrammatic Drawing of the Propeller Airflow. 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PRO “propeller root—That part of the propeller blade near the boss. “propeller section—A cross section of a propeller blade made at any point by a plane parallel to the axis of rotation of the propeller and tangent at the centroid of the section to an arc drawn with the axis of rotation as its center. * propeller thrust—The component parallel to the propeller axis of the total air force on the propeller. Its symbol is T. propeller thrust—The pull of the propeller in the forward di- rection of its axis. Propeller thrust in pounds is roughly equal to three times the horsepower. “propeller torque—The moment applied to the propeller by the engine shaft. Its symbol is Q. * propeller, tractor—A propeller mounted on the forward end of the engine or propeller shaft. (It is usually forward of the fuselage or wing nacelle.) * propeller-width ratio, total—The product of blade-width ratio at the point of maximum blade width by number of blades. * propulsive efficiency—The ratio of the product of effective thrust and flight speed to the actual power input to the propeller as mounted on the airplane, consistent units being used throughout. pulsate means to throb or beat. Pulsation occurs in the in- duction system of an engine when a gap occurs between the intake of gas to the cylinders. “purity (of gas)—The ratio of the pressure of the hydrogen (or other aerostatic gas) in the container to the total pres- sure due to all the contained gases. “pusher airplane—See AIRPLANE, PUSHER. "pusher propeller—See PROPELLER, PUSHER. push rod—Part of valve mechanism which transfers motion of cam follower to valve actuating rocker arms. pyrometer (electrical)—A device using a thermo-electric couple wherein the difference in the temperatures at the junction of two metals produces an electric current meas- ured on a galvanometer calibrated in degrees. Upper limit 2500° Fahrenheit. pyrometer (mechanical)—A device for determining tem- perature, which makes use of the different coefficients of expansion of dissimilar metals to operate a hand over a gºated dial. The upper limit is about 1500° Fahren- eit. "quadrant—The operating lever, made on the arc of a circle, of a control surface of an airship, e. g., rudder quadrant, elevator quadrant. *quadruplane—An airplane with four main supporting sur- faces, placed one above another. quenching—The cooling of heated metal objects in water or oil for the purpose of tempering. quinoxes (the) are those points at which the ecliptic and equinoctical intersect, and when the sun occupies either of * positions, the days are of equal length over the earth. RAC "race rotation—The rotation, produced by the action of the propeller, of the stream of air passing through or influ- enced by the propeller. *radial engine—See ENGINE, RADIAL. *radial wire—See WIRE (AIRSHIP), RADIAL. radio, directional—See DIRECTIONAL RADIO. radius, bend—See BEND RADIUS. radius of action—The greatest distance to which an airplane can fly and have sufficient fuel supply remaining to return to the starting point. Radius of action is also called “navi- gation radius." “rail, docking—A rail or guide, constructed on the landing field and extending into the shed, which supplies a means for holding the lateral pull of an airship's docking or handling lines. The pull is transmitted to the rails from wheeled cars or trolleys which are fitted on or in the rails. Usually two rails are fitted at the greatest distance apart which will permit them to be run into the shed. rainbow is a spectrum in the sky due to the refraction, reflec- tion and dispersion of light rays on falling rain drops or mist. Light rays are a combination of all of the colors and the various colors have different degrees of refraction. Consequently the refractive power of the moisture drop- lets spreads the colors out in a band. See REFRACTON. *rake, propeller—See PROPELLER RAKE. *ram—The combination of tubes and springs which is mounted in gimbals at the top of a mooring mast. It con- sists of an outer tube which carries the gimbal mounting and within which slides an inner tube. The upper end of the inner tube carries the hollow cone which receives the airship's mooring cone and which is fitted to revolve freely. The inner tube can slide down into the outer tube and compress heavy springs, thus easing the shock when the mooring is made. "range at economic speed—The maximum distance a given aircraft can cover while cruising at the most economical speed and altitude at all stages of the flight. *range at full speed—The maximum distance a given aircraft can cover at full speed at sea level. range, gliding—See GLIDING RANGE. *rate of climb–The vertical component of the air speed of an aircraft, i. e., its vertical velocity with reference to the air. reaction — A force, equal and opposite to the force of the action producing it. reciprocal bearing—See BEARING, RECIPROCAL. reciprocal of a number is a fraction, i. e., 1 divided by the number. The reciprocal of five is one-fifth. "recorder, flight—An instrument for recording certain ele- ments of the performance of an aircraft. reflection—The turning back of heat waves by a material surface. refraction is the change from a straight line which a ray of light or heat assumes when passing through a smooth sur- face into a medium of greater density. Refraction of light REF rays through a prism produces a series of colors, because the components of the light ray have different rates of refraction and are, therefore, deflected at different angles. refraction introduces an error in celestial observations, be- cause the atmosphere refracts the light rays, and conse- quently the height of the sun when viewed through the sextant appears greater than it really is. The Nautical Almanac gives correction tables. +registration means entry of licensed aircraft in an official license registry of the Secretary of Commerce as aircraft of the United States. Unlicensed aircraft, though entered of record for purposes of identification as required by law, are not registered aircraft within the meaning of these regulations. *relative inclinometer—See INCLINOMETER, RELATIVE. relative humidity—See HUMIDITY, RELATIVE. *relative wind—See WIND, RELATIVE. relief map is one which shows variations in altitude above sea level by means of shading or layer tints of color shad- ing. Altitude for the various tints are shown in a legend. Altitudes may also be shown by printed figures over the map. representative scale—See SCALE, REPRESENTATIVE. repulsion of magnetic fields—See MAGNETIC FIELDS, ATTRAC- TION and REPULSION OF. residual magnetism—See MAGNETISM, RESIDUAL. resistance (deadhead)—The structural head resistance of all parts taken together, but not including the lifting sur- faces. See PASSIVE DRAG. “resistance derivatives—Quantities expressing the variation of the forces and moments on aircraft due to disturbance of steady motion. They form the experimental basis of the theory of stability, and from them the periods and damping factors of aircraft can be calculated. In the general case there are 18 translatory and 18 rotary derivatives. lateral—Resistance derivatives expressing the variation of moments and forces due to small changes in the lateral, yawing, and rolling velocities. longitudinal — Resistance derivatives expressing the variation of moments and forces due to small changes in the longitudinal, normal, and pitching velocities. rotary—Resistance derivatives expressing the variation of moments and forces due to small changes in the rotational velocities of the aircraft. translatory—Resistance derivatives expressing the va- riation of moments and forces due to small changes in the translational velocities of the aircraft. resistance (electrical)—The resistance offered by conduc- tors to the passage of electricity. The ohm is the unit of electrical resistance. resolution of forces is the process of finding the component forces which produce a given resultant force. resonance in radio work is the principle which demands that RES the receivers and transmitters in radio communication must be in tune (equal vibrations) in order that the signals may be audible in the receiver. *restoring moment—See RIGHTING MOMENT. resultant of two or more forces acting on a body is the single force which, if acting alone, would produce the same effect as the several forces combined. retarded, uniformly—See UNIFORMLY RETARDED. retentivity is the power of iron and steel to resist demagneti- zation. reverse control is the situation that exists when an airplane is maneuvered to such an extent that the control surfaces reverse their function. For example: In a vertical bank the elevators act as a rudder and the rudders act as an elevator. The elevators are still lifting the nose around the turn, but are acting as a rudder when the turn is con- sidered in relation to the ground. “reverse turn—See TURN, REVERSE. “revolutions, maximum—The number of revolutions per min- ute corresponding to the maximum horsepower. “revolutions, rated—The number of revolutions correspond- ing to the rated horsepower. *Reynolds Number — A name given the fraction p- vi in which Al p is the density of the fluid; V is the relative velocity of the fluid; l is the linear dimension of the body. p is the coefficient of viscosity of the fluid. rib, box—A rib built in the form of a solid box at the junction of the wing and fuselage. rib, compression — The compression stress-bearing ribs in the framework of an airfoil. rib, false—Short form ribs between the front spar and the leading edge, used to improve and maintain the camber of the airfoil. rib, form—The lighter, form-giving parts, used in airfoil construction. rib, lightening—See RIB, FORM. “rigger—One who is employed in assembling and aligning aircraft. "rigging (aerostat)—The attachment and adjustment of the car, rudders, valves, controls, etc., of an airship. ‘rigging (airplane)—The assembling, adjusting, and align- ing of the parts of an airplane. rigging position—That position of an airplane when the longitudinal axis (usually parallel to propeller axis) is level with respect to the ground. right ascension of a heavenly body is the arc of the equator intercepted between the prime meridian and the meridian of the body, and is always measured to the east of the prime meridian. Right ascension is celestial longitude. "right-hand engine—See ENGINE, RIGHT-HAND. AzA v.27:22.5 aczza? a's e^zz»47&_\ j An Airplane in a Vertical Bank. AZAVZ7223 &czyoa/ /s /**2/2/zazez’ ay 22,224Fe , 2. . Lº 2. 2% 2^ % f> Low Winged Pursuit Airplane (U.S. Air Corps P-40). t.)| !!!! %№ S.|- -}' + § . . º.) §. Ñ• È.（ ∞ - -！：） ------ paeº N§§N|N . | . || `№，0 . Passenger Transport (Douglas DC-5). RIG *righting moment (or restoring moment)—A moment which tends to restore an aircraft to its previous attitude after any small rotational displacement. *right side (engine)—That side which, to an observer look- ing from the antipropeller end toward the propeller end, lies on the right-hand side. *rigid airship—See AIRSHIP, RIGID. *ring, concentration: airship—A ring to which several rigging lines are led from the envelope and from which one or more lines also lead to the car. free balloon—A ring to which are attached the ropes sus- pending the basket and to which the net is also secured. Sometimes called “load ring." *ring, load—See RING, CONCENTRATION (FREE BALLOON). *ring, mooring—A metallic ring suspended from one of the forward frames of a rigid airship by wire lines and used for mooring. The vertex of a “three-point mooring" is attached to this ring. *rip cord—See CORD, RIP. *rip panel—See PANEL, RIP. rhumb line—A line on a map or chart cutting all meridians at the same angle. Any straight line on a mercator pro- jection is a rhumb line. rocker arm—Intermediate valve mechanism part which actu- ates valves. It is the connecting link between the push rod and the valve stem. In some cases the rocker arm works directly from the cams on in-line engines. rod, connecting—See CONNECTING ROD. rod, push—See PUSH ROD. *roll—A maneuver in which a complete revolution about the longitudinal axis is made, the horizontal direction of flight being approximately maintained. roll, to-To turn about the longitudinal axis. roll (aileron) can only be executed with a plane of excellent maneuverability, and is accomplished by making a com- plete roll about the longitudinal axis with the aileron con- trols only, except that a little top rudder is used to keep the nose on the horizon when the wings are vertical. “roll, angle of See ANGLE OF ROLL. roll (barrel) is a full roll about the longitudinal axis from normal flight attitude through inverted position and on around to normal attitude again. roll (half) is a half roll about the longitudinal axis from normal flight to inverted flight or from inverted flight to normal flight position. roll (half from the top of a loop) is accomplished by pushing the stick forward and using full aileron and rudder in the desired direction of roll. As the plane rolls over the con- trols should be neutralized and the pilot may expect the necessity to recover from a partial stall. *rope, drag—A long rope which can be hung overboard from a balloon so as to act as a brake and a variable ballast in ROP making a landing. Same as "trail rope or “guide rope.” On airships a similar rope or ropes is used as a haul-down or mooring line by the landing crew. It is usually larger and longer than a regular handling line. Sometimes called "grab line." *rope, mooring—A line attached to a balloon or airship for use in securing it to the ground. It may serve the purpose of a “handling line," or vice versa. *rope, trail—See ROPE, DRAG. rotary converter is similar to a motor generator except that it is a single unit with the direct and alternating current windings on the same armature. "rotary engine—See ENGINE, ROTARY. rubber is used for shock cord on landing gear and tail skid. Shock cord is made of a bundle of rubber bands with a woven cloth covering. The covering is woven loosely and on the bias to stretch with the rubber. Rubber is also used for engine mounting and radiator mounting pads, hose connections, etc. Rubber insulation is used extensively in the electrical system. *rudder—A movable auxiliary airfoil, the function of which is to impress a yawing moment on the aircraft in normal flight. It is usually located at the rear of an aircraft. rudder—A movable auxiliary control surface, used to give directional control about the vertical axis. "rudder (airship)—A hinged or pivoted surface, usually at- tached to a fin at the after end of an airship. When oper- ated by the pilot it produces a yawing moment and gives directional control in the plane at right angles to the axis about which it is hinged or pivoted. *rudder angle—See ANGLE, RUDDER. "rudder bar—The foot bar by means of which the control cables leading to the rudder are operated. *rudder torque—The twisting moment exerted by the rudder on the fuselage. The product of the rudder area by the distance from its center of area to the axis of the fuselage may be used as a relative measure of rudder torque. runners or skiis are used on airplanes for landing on snow and ice. runner, central—See CENTRAL RUNNER. running fit—See FIT, RUNNING. safety belt—See BELT, SAFETY. “safety, factor of See FACTOR OF SAFETY. safety gap—A high resistance air gap across the high ten- sion (secondary) circuit designed to allow a discharge of high potential if the secondary circuit fails. “safety loop—See LOOP, SAFETY. “sag—A distortion of an airship in which the longitudinal axis becomes concave upward so that both ends rise. sailplane—A soaring craft. "sandbag line—See LINE, SANDBAG. sand blasting is used to clean metal surfaces and castings and remove oxides and corrosion. It is a high velocity jet of sand and air directed against a surface, and is also used to roughen smooth surfaces. 2. H Aea/coezze ex42&s /ºxezzºe, Arezze, A4ezss Hººgee ze.” e cae ºv, Aºx22/7/2 Coa/veazzoazz zazz 24/7′ſe, /V/or 7zęże a/4 o ca/AZ-5.5/5- ) A Typical Helicopter. …” > * % w): sº º ~i=sº 77/242&A=avce Gº; ) (; Žº º º: ~s %&_* A sº © _-r—ºf I-- 22-s 2: =s –5,2244. 7&eezzecce = ~ 36.5°E Sº $3.5 === ~s =aº-º-º-º- The Airflow about a Circular Form and a Streamline Form. •----- *- º, ſº tº a a tº “º sº lſ --- tº ** Pical Si Moś., "sle Float Seaplane (V - Ought Scou t SAT saturation—The condition of the air when it contains all of the water vapor it can hold under existing conditions. saturation, magnetic—See MAGNETIC SATURATION. scalar quantities have magnitude only, such as volume, den- sity, and energy, and have no reference to distance or direction. Scale, Beaufort—See BEAUFORT SCALE. scale effect is the reconcilement necessary to wind tunnel model experiment tabulations due to the fact that models are comparatively small in linear dimensions, thus intro- ducing effects which must be accounted for in calculating the performance of full scale aircraft. scale, graphical refers any distance on a chart or map to a line graduated in units of distance. scale (map or chart)—The designation of the scale used in constructing the map or chart. scale, representative is a fraction printed on charts and maps which indicates the ratio between distances on the map or chart and the actual distances on the surface of the earth. For example: 1/63,360 means that one inch on the map equals 63,360 inches (one mile) on the earth's surface. scale, statement is a scale indication on a chart or map which states that one inch equals one mile or expresses whatever unit relation that the cartographer has chosen. scoop, air—See AIR SCOOP. *sea anchor—See ANCHOR, SEA. *seaplane—Any airplane designed to rise from and alight on the water. This general term applies to both boat and float types, though the boat type is usually designated as a “flying boat.” “secondary shear wire—See WIRE (AIRSHIP), SECONDARY SHEAR. self induction is the current induced in a coil by the collapse of magnetic lines of force cutting adjacent turns of the coil when the switch is opened in the circuit. semi-diameter correction for observations of the sun is nec- essary, because the observations are usually taken of the upper or lower rim or "limb" of the body, and the obser- vation must be corrected by half the angular diameter of the body's disc. Corrections are tabulated in the Nautical Almanac. *semirigid airship—See AIRSHIP, SEMIRIGID. *service tank—See TANK, SERVICE. sextant—An instrument with which sun and star sights are taken so that the altitude thereof may be determined in degrees and minutes of arc. “shaft, climbing—An access shaft fitted with a ladder and leading from the bottom to the top of an airship hull. This may be fitted in an airship of any type. “shaft, gas—A duct or shaft leading from the bottom of the gas cells to the outer cover of an airship. It affords a clear passage for the escape of gases which have accumu- lated in the gangway or corridor or which are discharged from the valves at the bottom of the cells. It usually con- sists of light wooden hoops or frames spaced at intervals on cords or wires and is covered by a netting. It pre- SHA vents the gas cells from closing hard against one another and thus keeps the passage open. Sometimes called “gas trunk,” “exhaust-gas shaft," or "trunk." In view of the possibility of confusion with parts of an engine-exhaust system, it is believed that "gas shaft" or “trunk" is to be preferred. shaper is a machine designed to finish metal surfaces to the required shape by means of a machine tool which travels back and forth over the work. “sheathing—See TIPPING (PROPELLER). ‘shed—A shelter for housing airships. shielding is a method of blanketing the electrical system of an airplane engine to prevent ignition interference with radio equipment. "ship—Slang for an airplane. In view of the confusion with “airship" it should not be used. ‘shipplane—A landplane designed to rise from and alight on the deck of a ship. “shock absorber—A device incorporated in the landing gear of an aircraft to reduce the shock imposed on the struc- ture when alighting or taking off. Shock-absorbing de- vices are usually interposed between the main structure and the wheels, floats, skis, or tail skids, to secure resil- iency in landing and taxying. “shore—A structural member for supporting the structure of a rigid or semirigid airship during building or docking, used in conjunction with (or without) a cradle. shrinkage is a reduction in the bulk or dimensions of a body. Also applies to the tightening of fabric when dope is applied, or moisture-laden material is allowed to dry. shrink fit—See FIT, SHRINK. shutters—Adjustable covering over radiator or engine to control engine temperature. *side car—See CAR, WING. side elevation drawing shows the true shape of an object as viewed from the side. sidereal day is the interval between the successive transits of the first point of Aries across the same meridian. Sidereal time and mean time are convertible by means of the Nautical Almanac. sidereal time is the hour angle of the first point of Aries (vernal equinox), and is the origin of all co-ordinates of right ascension. This is a fixed point and, therefore, has the properties of the fixed stars, thus giving rise to the statement that sidereal time is time by the stars. "side slipping—Flight in which the lateral axis is inclined and the airplane has a component of velocity in the direction of the lower end of the lateral axis. When it occurs in ſººn with a turn, it is the opposite of skidding. q.V. side slip is a maneuver to lose altitude at a minimum forward speed, and is accomplished by using high rudder while in a bank. The nose of the plane should be kept below the horizon to prevent loss of forward flying speed, which SIG might reach a stali. “sighting pendant—See PENDANT, SIGHTING. sine of an angle is the vertical leg of a right triangle divided by the hypotenuse. The sines of the angles 1° to 4° are useful in determining the rise of a wing tip for lateral dihedral. The rise in inches of any point along the spar is equal to the distance of that point in inches from the center times the sine of the angle of rise desired. Sine of 1° = .0174 2° = .0349 3° = .0523 4° = .0698 skew aileron—See AILERON SKEw. ‘skid—A runner used as a member of the landing gear and designed to aid the aircraft in landing or taxying. tail skid—A skid used to support the tail when in con- tact with the ground. wing skid—A skid placed near the wing tip and de- signed to protect the wing from contact with the ground. *skidding—Sliding sidewise away from the center of curva- ture when turning. It is usually caused by banking insuffi- ciently, and is the opposite of side slipping (q.v.) *skid fin—A fore-and-aft vertical surface, usually placed above the upper wing, designed to provide vertical keel surface and so to increase lateral stability. “skin friction—The tangential component of the fluid force at a point on a surface. *sky writing—The act of emitting from an aircraft a trail of smoke or other visible substance, the flight of the aircraft being so directed as to cause the trail to assume the form of letters or symbols. “sleeve, conical—A cone-shaped fabric, fitting in a bag or cell through which a line passes. It provides a gas-tight connection of the bag or cell to the line and yet permits both some degree of freedom to move. “sleeve, deflation—Generally a sleeve or appendix made of fabric provided for the special purpose of facilitating the deflation of an aerostat. Also applied to the sleeve or appendix fitted in the lower lobe of a kite balloon and used to permit the rapid escape of air in the lobes when the balloon is hauled down. “sleeve, filling—See SLEEVE, INFLATION. “sleeve, inflation (or sleeve, filling)—A tubular fabric attach- ment to an envelope or gas bag, serving as a lead for the inflation tube. sliding valve—See VALVE, SLIDING. “slip—The difference between the mean geometrical pitch and the effective pitch. Slip may be expressed as a per- centage of the mean geometrical pitch or as a linear dimension. SLI “slip fuel tank—See TANK, SLIP FUEL. *slip function—The ratio of speed of advance through the undisturbed air to the product of propeller diameter by the number of revolutions in unit time, i. e., RPF The N D slip function is the primary factor controlling propeller performance. It is it times the ratio of forward speed to the tip speed of the propeller. sling psychrometers—An instrument for determining abso- lute humidity, vapor pressure, dewpoint, and relative humidity. "slip stream—The stream of air driven astern by the pro- peller. (The indraft is sometimes included also.) slots are automatic or fixed auxiliary surfaces at the leading edge of wings designed to increase the burble angle by directing a more efficient air stream over the wings at higher angles of attack. small circle—See CIRCLE, SMALL. *snatch-block anchorage—See ANCHORAGE, SNATCH-BLOCK. "soar—To perform sustained free flight without self-propul- sion; it is called "up-current soaring" if performed in ascending air; “dynamic soaring" in other cases. soaring is sustained free flight above the starting point with- out self-propulsion. soaring is possible under air conditions such that the loss of altitude because of the gliding angle is less than the in- crease of altitude because of rising currents of air or dynamic reaction to air movements. soaring, blind—See BLIND SOARING. soaring, cloud—See CLOUD SOARING. soaring (dynamic) is accomplished by utilizing the kinetic energy of the soaring velocity to obtain lift from changes in the wind velocity. soaring plane is an aircraft capable of sustained free flight without self-propulsion. soaring (static) is soaring on the up-currents of air, such as convection currents and thermic up-currents. solar day is the time between two successive passages of the sun across the same meridian. The hour angle of the center of the sun is the measure of apparent or solar time. solo is to fly alone or to be in command of the aircraft. solstices (solstitial points) are points of the ecliptic at a distance of 90° from the equinoxes and at which the sun attains its highest declination. They are called the sum- mer and the winter solstices, according to the season in which the sun appears to pass their points in its path. “sounding balloon—See BALLOON, SOUNDING. "sound-ranging altimeter——See ALTIMETER, SOUND-RANGING. sound, velocity of See VELOCITY OF SOUND. “span (airfoil)—The lateral dimension of an airfoil, i. e., its dimension perpendicular to its chord. Its symbol is b. “span (airplane)—The maximum distance measured parallel to the lateral axis from tip to tip of an airplane inclusive Jºžoz /ey casea acs/7Zoey $4////CAV coa'Zºs/2aºy/CºS 7 o A//cºa/ 3A2a: E.P AETZ/eºſ/T Sºlor zay ceeay eas/7/2// PVA//c// coa'42.45s/2O/Y&PS 2"o Z o lºv -s/>Ae 47 c cº- •S 7/74.4//ºr G ºv/"777°4′2.É. A Typical Wing with Leading Edge Slot. 45&7-ſay Z. &aaſaya, a 40&A=. -:427. A/Y /2/42/Ezy/Z_- Ž, Zze 2/ J427 / 2&zz //zzz za zeroz axe eezsswzs Zºo Azazeezzaza Ze/77. ZZ Zax way Zºe azazzarzazzazz 2/* Azzézzav <2/yzzzaz, Aazoºv Avozazawa Jºzzz//v42 -5°E&a. Ze 2C- zoa, 2-ze-Z27 /s sazzazz z2 aſ rearrarely a zwar /7 Jessos 22 7ze ºzzer erez azczeze: 722 y Zrzaz. A Built-in Leading Edge Slot. Że zazerºszoºs or x-r-z Aze t J2E76/2/07//YA:P ey WZ/Z 7z/May/ea. At x- X ++ Aea/area/7/77/ory. 77/Ese Azee ex- AºA'ss EP //y areafaea/7 or 77'ye cºoetz'. / _2^ Axed A.45/7P//Yoº A5 ADGE / Aºeaz. AZaz/EO//- ca. J.A.O.7" A /*a*, 1/~e. A Modern Airfoil with Fixed Leading Edge Plane or Slot. 47se zcz &ze = A”. AP Aſ=/eeway-seº.ºr 7&a=2. Aºro = c 7 2/s alary Aceaz aezazzz's Aºz///27/CAEPZ Z//E7".22/~572/434/7Zoey Jeevar = & Aºse zeeez. \, <52/7 72,744/6 * AfDGeº AT/.///? `Ax/24//p/yº, AZZAF7" | | | 2 |J.F. &//e7cal cross seczzazzazzsezºe. The Proportions of a Modern High Performance Low Winged Monoplane. Z/A-7 aſ 37.2/earz/ory ear 2 24-7.7%azze rºck, 424/27/c4/ Z/Ar 2/sze/ae/7/ory a/Y AW 7/7/2A-A*A*/5 27.4 ſ ,, . Hº Hºr TFE, / 77°4235 / } | | | | | | | | | | º, 11 Il | | li | ill- + 1–1–1 | ill º iſſiſtasiſ º \ | | * | - \ illili | | | | | | | | | | || //A sºaze Aegaz & Zzer ooze/ae/7/a^' Azzº's 7 o aſ 43/AZaaya' o/*-s/ozzz/7/2. A voz, a 4/472/7c-7-A-e/.57/cj The Distribution of Lift across the Wing Span of a Tapered Wing. SPA of ailerons. “spar—See WING SPAR. spark advance and retard–The range of spark occurrence before and after top dead center. spark plug-A unit holding the positive and negative elec- trodes which form the spark gap in a combustion chamber. *specific fuel (or oil) consumption—See FUEL (OR OIL) CON” SUMPTION, SPECIFIC. specific gravity—See GRAVITY, SPECIFIC. specific heat is the heat necessary to raise the temperature of one pound of any substance one degree Fahrenheit and is expressed in B. T. U. spectrum—The colored and other rays of light such as ap- pear in a rainbow and which have been separated from light rays by refraction. Light rays possess all of the spectrum colors, but they are only visible when refracted or broken up by a prism. In a rainbow the water drop- lets furnish the prismatic agent for refraction. “speed, critical—The lowest speed of an aircraft at which control can be maintained. “speed, economic—The speed at which the fuel consumption, per unit of distance covered in still air, is a minimum. speed of electrical waves, as used in radio communications, is the same as the speed of light (186,000 miles per second). “speed, ground—The horizontal component of the velocity of an aircraft relative to the earth. “speed, landing—The minimum speed at which an airplane can maintain itself in level flight and still be under ade- Quate control. speed landing usually applies to the fast landing of a sea- plane on the step of the boat or pontoons. This is analo- gous to a two-point landing on wheels. “speed, minimum—The lowest steady speed which can be maintained by an airplane in level flight at an altitude large in comparison with the dimensions of the wings, with any throttle setting whatever. sphere—A solid body, all points on the surface being equi- distant from a common center. sphere, celestial—See CELESTIAL SPHERE. "spin–A maneuver consisting of a combination of roll and yaw, with the longitudinal axis of the airplane inclined steeply downward. The airplane descends in a helix of large pitch and very small radius, the upper side of the airplane being on the inside of the helix, and the angle of attack on the inner wing being maintained at an ex- tremely large value. spin (flat) is a condition of rotation about the vertical axis while the longitudinal axis is nearly level. Ailerons are ineffective because the airplane is in a stall and the down- ward path of the falling airplane and the rotation carries the tail control group away from the slip stream. To recover, upset the balance of the airplane by moving SPI weight forward. spindle, mooring—See OUTRIGGER, MOORING CONE. “spinner—A fairing of approximately conical or paraboloidal form, which is fitted coaxially with the propeller boss and revolves with the propeller. “spiral—A maneuver in which an airplane descends in a helix of small pitch and large radius, the angle of attack being within the normal range of flight angles. “spiral instability—See STABILITY. spirits—Non-freezing liquid used for filling compass bowls. spirit level—A glass tube filled with spirits and containing an air bubble. Position of bubble in reference to calibra- tion marks indicates level attitude. splice is the joining of the ends of two pieces of rope, wire, or wood in such a manner that the splice (joint) is just as strong as the material spliced. spring, valve—See VALVE SPRING. spruce is of clear silver grain, straight, smooth, and free from knot holes or sap pockets. It is the lightest, strong- est and most generally satisfactory material for airplane construction available. It must be properly ferruled where fittings are attached to prevent splitting. As a material for spars, ribs, struts, etc., it gives a splendid combina- tion of flexibility, lightness and strength. squall is a sudden blast of wind of comparatively short duration. A squall subsides as rapidly as it occurs. Squalls occur when there is a large difference in atmos- pheric pressure of adjacent areas. squall, line is a squall which occurs along the line (perhaps 200 miles) separating areas of large atmospheric pres- sure difference. Line squalls are characterized by a rapid rise in pressure, sudden increase of wind velocity fol- lowed by a lull, veering wind direction, and a cloudy condition with precipitation. square root of a number is that number which, when multi- plied by itself, will equal the number. Thus the square root of 4 is 2, because 2 × 2 = 4. “stability—That property of a body which causes it, when disturbed from a condition of equilibrium or steady mo- tion, to develop forces or moments which tend to restore the body to its original condition. automatic—Stability dependent upon movable control surfaces automatically operated by mechanical 11162a1nS. inherent—Stability of an aircraft due solely to the dis- position and arrangement of its fixed parts, i. e., that property which causes it, when disturbed, to return to its normal attitude of flight without the use of con- trols or the interposition of any mechanical devices. static—Stability of such a character that, if the air- plane is displaced slightly from its normal attitude by rotation about an axis through its center of grav- ity (as may be done in wind-tunnel experiments), moments come into play which tend to return the Aºzé e/ Zazzasavce Y Aze Awazazzaz 72 zazareas? 4//we 2/75Z.4.5/2 12…asY ſ B * (3) - d - - - –ºr "r- - - - ...’ Žºjz As of ayazzeavoe. * {Zºre ©/º 7%.<57 / 5 `AzazaaZZZAZ 72 ZZººs 4raº -** - -smºs Że zowo/zzo'az szza/z/ry /s Govzza/EZ ey. 7% z/Aroaze h/res /w/azºº/*37%&A& A/Azzºe. /y & szzzz,7//E Zowee WAY& Zases /73 Zz-Z &éazze= 7//s caree w/º. 4's sooey as 7//s occas, 7/8 Azaz//ſe Mases ao/varwaved. 7% as Arece arczs weezzz zaz Azzºz. 2, 7& &aesz. ºvate. A rºe area.a.r.s awases coevaºwazz, zze &esaEEZ 2&s aro Zºe Zoºe PºžA/3 &AEA/EAE/777&s / 7.5 wagazz A /º/, /7//Z2 /2.5.5&A2575 AA=12& Azzºz. 4/ºzess Zºéf-S 7244, AS Woºleav/, ///e 4/a^ea ſwayo AE/Mºy's 57/784& A'z AZZ 7/Azes. 477 Avcº Awaza; 24 ºz72pze: 7//E AoP1/E/2 44//Yeº 75A/O5 7 o Aºoſ Z //5, /7 .5267 AV Aºzºa Aſa A 7&n ZŽ &/ºe Py/A/6. A Tvpical Biplane with Negative Stagger (Beech- craft). Auopea. AZY-- - - - - Aºyce W/EE5 –52areazzez's –2.2e2/zee, AZ2/2/3ravº SS —- //-ca,27, a 5- ºr ºt. --- ~~~~ Xºliºs - -- - -º- - ---. Afyzzzes -57s ºrzzzee /5 Azºzoea ×72& 7&6/aſg. * A/?? Aºº/C Cayºº. Afterºzee- Złºsz, Zzzee, * af A £: AW/MC2 ºv//EEZ faly 77.3///ZAFA2's Azer's cºzzºz. *— Žezeze A/Fc/º/v/.5Af /*ZEx/a43 cºale The Stabilizer Control on a Fleet Biplane. 4/27 / 22ce f __-/-aceae: Zºzz aervaz 2/22 ~! AZ/.57° 43A2Z/26/c &- - - Arezz//7" | _- Mezzar as ºs- 54/A-7A:D 72 A34: y Covay ceasy 2 aſſº V AFC) AP7 74& ce/yzee of azeºr/7′Y 00 Gº Meazear z x wear = azeºretºr'y"x zzz zewozozo z. zoeazz Azºr The Action of the Stabilizer as a Balancing Member on an Airplane (Curtiss Wright Interceptor). 47.4 arezzº. -> rºeſ, £2 & ſºlº W 2s / ceae. af The Horizontal Tail Surface of a Boeing B-17. t ** g * .* /*eze coveeso =4&varez" t &V. ; : 'Zazaze Jºe'e 720s – \ Aa3/7/rz Jºzºgee. Aſega/7/ve -57A;6=e_. Typical Positive and Negative Staggered Biplane Cellules. STA airplane towards its original attitude. dynamic—Stability of such a character that, if the air- plane is displaced from steady motion in flight, it tends to return to that steady state of motion, the oscillations due to restoring moments being damped out. In a general way, the difference between static stability and dynamic stability is that the former depends on restoring moments alone, while the latter includes the action of damping factors. longitudinal—Stability with reference to disturbances in the plane of symmetry, i. e., disturbances involv. ing pitching and variation of the longitudinal and normal velocities. directional—Stability with reference to rotations about the normal axis, i. e., an airplane possesses direc- tional stability in its simplest form if a restoring moment comes into action when it is given a small angle of yaw. Owing to symmetry, directional sta- bility is closely associated with lateral stability. lateral—Stability with reference to disturbances in- volving rolling, yawing, or side slipping, i. e., dis- turbances in which the position of the plane of symmetry of the aircraft is affected. spiral instability—A type of instability inherent in cer- tain airplanes which becomes evident when the air- plane, as a result of a yaw, assumes too great a bank and side slips; the bank continues to increase and the radius of the turn to decrease. “stabilizer—A normally fixed airfoil whose function is to lessen the pitching motion. It is usually located at the rear of an aircraft and is approximately parallel to the plane of the longitudinal and lateral axes. Also called “tail plane." “stabilizer (aerostat)—Same as FIN. The lobes of a kite bal- loon are sometimes referred to as stabilizers. stability (pendulum) exists when the center of gravity of an airplane tends to assume a position below the center of pressure. “stabilizer, mechanical—A mechanical device to prevent an aircraft from departing from a condition of steady mo- tion, or, in case such a motion is disturbed, to restore it to its steady state. Includes gyroscopic stabilizers, pen- dulum stabilizers, inertia stabilizers, etc. “stabilizer setting, angle of See ANGLE OF STABILIZER SETTING. stabilizer, vertical — A vertically fixed auxiliary airfoil whose function is to lessen yawing effects about the ver- tical axis. “stable oscillation—See OSCILLATION, STABLE. “stagger—The amount of advance of the leading edge of an upper wing of a biplane, triplane, or multiplane over that of a lower, expressed either as a percentage of gap or in degrees of the angle whose tangent is the percentage just referred to. It is considered positive when the upper wing is forward and is measured from the leading edge STA of the upper wing along its chord to the point of inter- section of this chord with a line drawn perpendicular to the chord of the upper wing at the leading edge of the lower wing, all lines being drawn in a plane parallel to the plane of symmetry. “stall—The condition of an airplane when from any cause it has lost the air speed necessary for support or control. stall landing—See LANDING (STALL). stall (whip) is a violent longitudinal rotation about the lateral axis following a full stall, and is due to the nose- heavy balance of an airplane. Called a cut-power stall when the throttle is closed near the peak of the stall. Severe strains occur on the engine mounting. Hard rud- der before the upswing is completed will prevent. stars (fixed)—Stars whose declination is always the same (constant). statement scale—See SCALE, STATEMENT. “static ceiling—See CEILING, STATIC. “static lift—See LIFT, STATIC (AEROSTAT). static soaring—See SOARING, STATIC. “static thrust—See THRUST, STATIC. “static trim—See TRIM, STATIC. “static turn indicator—See INDICATOR, STATIC TURN. "station, airship—The complete assembly of sheds, masts, gas plants, shops, landing fields, and related equipment required to operate airships and supply their needs. A station may include all or a part of the items enumerated. The base from which airships are operated. “statoscope—An instrument for detecting minute changes of altitude of an aircraft. The indications of the instrument usually depend on small changes of the static pressure of the air. statute mile—5,280 feet. "stay—A wire or other tension member; for example, the stays of the wing and body trussing. stem, valve—See VALVE STEM. “step—A break in the form of the bottom of a float or hull designed to reduce resistance when under way by rapidly reducing the wetted surfaces as speed increases. It also serves to eliminate suction effects. "stern-droop—A deformation of an airship in which its lon- gitudinal axis bends downwards at the after end. "stern framing—See FRAMING, STERN. *stern-heavy—The condition in which, in normal flight, the after end of an airship tends to sink and which requires correction by means of the horizontal controls. In this condition an airship is said to "trim by the stern." It may be due to either aerodynamic or static conditions, or to both. "stiffener, bow—A rigid member attached to the bow of a non-rigid or semirigid envelope to reinforce it against the pressure caused by the motion of the airship. Some- times called "nose stiffener" or "nose batten." storage battery (aviation) is a battery of leak proof design !) A Modern Airplane showing Braced Construction, Tractor Airscrew and Rigid Chassis (Monocoupe). _ºščiščSºśº º | Tºy STV /jS.N. a -\ ...----- - T->==------ * 2: ET A Typical Biplane (Grumman Navy Fighter). ſt-ſº - ... :S "Illyrºº T. D.C. D Ü - t –a– * * * a--i =-- | Hi | -— | $1. º :#fff; B.D. C. * = ** * * Length of Mechanical Positions. i T. D. C. s-- * *-* * 2. & º Stroke and Dead Center : ** sº * * * STR which will not discharge its liquid contents during violent Iſla Ile11 VerS. strain—A tendency to deformation of a member produced by stress. strainer screen (carburetor) is a fine wire mesh screen, usu- ally placed at the union of the fuel feed line and the needle valve, to prevent the introduction of foreign substances into the carburetor bowl. stratosphere—The upper layer of atmosphere above an alti- tude of about 40,000 feet. *streamline—The path of a small portion of a fluid relative to a solid body with respect to which the fluid is moving. The term is commonly used only of such flows as are not eddying, but the distinction should be made clear by the COntext. *streamline flow—Steady flow past a solid body, i. e., a flow in which the direction at every point is independent of time. *streamline form—A solid body which produces approxi- mately streamline flow. stress—Burden or load on a member. stresses are of five kinds: Compression, tension, shear, bending, and torsion. Compression is the squeezing of a member. Tension is caused by forces which tend to stretch a member. Shearing tends to cut across a mem- ber. Bending is caused by forces which are applied on a member at other than the supporting points. Torsional stress is caused by forces which tend to twist a member. *stresses, breathing—Stresses produced in an aerostat by breathing. Of importance in the envelope and keel of a semirigid airship due to the interaction of envelope and keel when the envelope “breathes.” stress, temperature—See TEMPERATURE STRESS. stress, working—See WORKING STRESS. striation is a vertical cross section of the bands of varying atmospheric structures which surround the earth. strip, cap—See CAP STRIP. “strip, drip—See FLAP, DRIP. stroke—The amount of travel of the piston between top dead center and bottom dead center (usually measured in inches or centimeters). *structural drag—See DRAG. *strut—A compression member of a truss frame. For in- stance, the vertical members of the wing truss of a bi- plane (interplane struts) and the short vertical and hori- zontal members separating the longerons (q. v.) in the fuselage. ‘strut, drag—A fore-and-aft compression member of the in- ternal bracing system of a wing. struts, interplane are the struts between planes (wings), and are usually called “wing struts." sublimation is a direct conversion of solids to vapor by heat evaporation without passing through any process of liquefaction. sub-stellar point—The place on the earth directly beneath SUM the star in question. sump (dry)—An engine having only small oil collecting cups from which the oil is pumped to an outside reser- voir or tank. sump (wet)—An oil sump in the base of the engine which carries the main supply or body of oil. "supercharged engine—See ENGINE, SUPERCHARGED. “supercharger—A mechanical device for supplying the en- gine with a greater weight of charge than would nor- mally be induced at the prevailing atmospheric pressure and temperature. centrifugal type — A supercharging device equipped with one or more rotating impellers generating cen- trifugal force which is utilized for the compression and the transmission of the air against resistance. positive-driven type—A supercharger driven at a fixed speed ratio from the engine shaft by gears or other positive means. rotary-blower type—A supercharging device compris- ing one or more relatively slow-speed rotors revolv- ing in a stationary case in such a way as to provide a positive displacement. turbo type—A supercharger driven by a turbine oper- ated by the exhaust gases from the engine. “superheat—The amount by which the temperature of the gas in the envelope or gas cells of an aerostat is higher than the temperature of the surrounding air. If the con- tained gas has a lower temperature, the superheat is said to be negative. superheat meter—See METER, SUPERHEAT. supply balloon—See BALLOON, SUPPLY. supply tube—See TUBE, SUPPLY. supporting surface, main—See SURFACE, MAIN SUPPORTING. surface, adjustable is a surface which may be adjusted while in flight. An adjustable stabilizer which may be adjusted to balance the airplane longitudinally is the most notable example. “surface, control—A movable airfoil designed to be rotated or otherwise moved by the pilot in order to change the attitude of the airplane or airship. “surface, fixed—See FIN. “surface, main supporting—A set of wings, extending on the same general level from tip to tip of an airplane; e. g., a triplane has three main supporting surfaces. The main supporting surfaces include the ailerons, but no other surfaces intended primarily for control or stabilizing pur- poses. suspension band—See BAND, SUSPENSION. suspension bar—See BAR, SUSPENSION. suspension line—See LINE, SUSPENSION. suspension, overhead—A line leading from the roof of an airship shed and arranged to sustain the whole or a part of the weight of the structure of an airship when it is docked. "suspension patch—See PATCH, SUSPENSION. Y Y X Y ¥ * * ¥ Jºsz rves - -, -ężory7 39/742. --7&ſearc Arzes \\ A/ye rºy 7'o SA/PA&S Ásarz seve- * --~ * =&ºss The Structural Details of Typical Welded Steel Tub- ing Control Surfaces. !--&ew. Aas * sº - * sº -- * sº sºft |: NTº ". | prº-Es- -7-ea, c. e " /*/º/aya, 7&zaraee -- The Structural Details of Typical Control Surfaces with Fabric Covering. ~>=wovøy/z/ ~><>/ew/a 577，7„~“ í «=>~&7&Çae)， _»• -->= zzzzzzzzg （ − √ avo2/377/^7 c7x7）<éZ7：/gº „º // ºzººK//// _Z/~//oe/ ^/ Çſ/ Saweyszczewey Sºvxzy „z Bºaz， ^ ^ ' ^^ $350，7 º/v/>&øe/ºs/w/sº o/ae/ : -7-224/ The Forces acting upon the Vertical Side Area. 7A/A -5/4/AAA%34& % 2. * Z7 2/5 ////*42. *e º AWA7%/5/2 7.O 7A/AF ZA'AºA) Z/Y& As age «2/y’. Y a-tº sºme º y- - - H--------- The Sweepback in a Modern Monoplane Wing i Ine (Douglas DST). TACHOMETER shorter instrument company, Brooklyn, New York The Internal Mechanism of the Tachometer of the Centrifugal Type. Pºnt-FR ºº Actual Size A Typical Tachometer of the Centrifugal Type. SUS “suspension winch—The rigging by means of which the lift and drag of a kite balloon is transmitted from the en- velope to the towing or traction cable. “sweep back—The acute angle between the lateral axis of an airplane and the projection of the axis of the wing on the plane which includes the lateral and longitudinal axes. (The axis of a wing is a line through the centroids of the section of the wing.) swinging base is a base or table divided into degree inter- vals on which aircraft may be placed to adjust compasses for deviation, and to obtain the necessary data for a deviation card. swishtailing is used to kill forward speed before landing by alternately using hard left and right rudder, the rudder action being controlled so that the plane swings right and left over the ground about the vertical axis without any noticeable change in the direction of forward motion. symbols are letters (often letters from the Greek alphabet) used to denote various factors. For example: V is the symbol used to denote velocity. symmetry, plane of LA vertical plane through the longi- tudinal axis about which the parts of an airplane are sym- metrical. tachometer—An instrument to register the revolutions per minute of the engine. * tail (airship)—Sometimes used for stern. * tail boom—A spar or outrigger connecting the tail surfaces and main supporting surfaces. “tail-droop—See STERN-DROOP. “tail group (or tail unit)—The stabilizing and control sur- faces at the rear end of an aircraft, including stabilizer, fin, rudder, and elevator. (Also called "empennage.") “tail-heavy—In a heavier-than-air craft, the condition in which, in normal flight, the tail sinks if the longitudinal control is released, i. e., the condition in which the pilot has to exert a push on the control stick to keep the given attitude. “tail-heavy (airship)—See STERN-HEAVY. *tail plane—See STABILIZER. *tail skid—See SKID. *tail slide—The backward and downward motion, tail first, which certain airplanes may be made to take momentarily after having been brought into a stalling position by a steep climb. tail wind—A wind blowing “from" a direction opposite to the heading of the aircraft, i. e., blowing in the same di- rection as the heading. This is a helping wind as far as ground speed is concerned, but it is a distinct disadvan- tage on the take off. take off—Attaining flight with an aircraft from a starting position on land or water. *tandem airplane—See AIRPLANE, TANDEM. *tank, fixed fuel—A fuel tank which is not intended or fitted to be dropped, as “slip" tanks are. TAN * tank, service—A fixed fuel tank near each power unit, into which fuel from other tanks is pumped and from which the fuel supplying the engines is drawn. * tank, slip fuel—A fuel tank which is provided with a device permitting the quick dropping of the tank and contents as a whole in case of an emergency. Fitted on both air- ships and airplanes. “taxi-To run an airplane over the ground, or a seaplane on the surface of water under its own power. temperature is the thermal or heat condition of a body or gas with reference to its ability to transmit heat to other bodies or gases. temperature inversion—See INVERSION, TEMPERATURE. temperature stress is caused by preventing the deforma- tions (expansion or contraction) which would naturally occur as a result of temperature changes. tempering—Term generally applied to heat treating of tools for hardness, or the heat treating of metal parts. template is a pattern from which structural sections, rivet holes, drilled holes, cowlings, coverings, etc., are marked Out. temporary magnet—See MAGNET, TEMPORARY. "testing, performance—The process of determining perform- ance characteristics. theodolite—An instrument especially adapted to the sur- veying of observation balloons. thermic up-currents are caused by the radiation of the sun's heat by the earth. thermodynamics (first law of)—"When mechanical energy is produced from heat, a definite quantity of heat goes out of existence for every unit of work done and con- versely, when heat is produced by the expenditure of mechanical energy, the same definite quantity of heat comes into existence for every unit of work spent." “thermograph—An instrument for recording temperature. thermometer—An instrument for determining temperature. “thimble—A grooved ring of circular, pear-, or heart-shaped form, generally of metal, which is inserted in the eye of a rope or wire to prevent chafing or deformation of the eye. thimble is the small metal part over which the loop of a wire terminal is made. The thimble preserves a smooth curve in the wire loop and prevents a sharp bend in the wire. three-point landing—See LANDING, THREE-POINT. “three-point mooring—See MOORING, THREE-POINT. throttle—Pilot's control lever to operate butterfly valve in carburetor. thrust bearing—A bearing designed to transmit the propel- ler thrust acting through the crankshaft to the crankcase of the engine. "thrust, effective—The net driving force delivered by a pro- peller when mounted on an airplane, i. e., the actual thrust given by the propeller, as mounted on the airplane, }Z/A-7”/åeceA， Y/^yº a'r Ceſayze， ºr'，F）- • ••- - - - - - --> >~| I №.Q || !ºsezaºGºG（~{| !<！---• • • •===>--◄æ• – •- • •-, -， → !•- - -， →----- | （ !7，5mē，77ēõūrā5，77-± • → * …?! |----><！--#-----------+----~-----~--~~~~&-------=） ----+-----; |�|%%&T ZDºº` ~ „）;** |i ' || ~ ~~~~ ~~~~)_P- - - --★ →· į！*®， ~·！—t→|! /， ez |•Z2 |N^?^/O/^/G cºaeaeza， Zayzwe！|Q'/?.G. !i Çi„4-r?ºzzººzzº Araş,|| ||};|_！\wºº !! 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Qo z’ \ 2 : (2 ! {} \ ...” N0° Z-z-z-z-r .* 's * ºº A. * | - VAL VE CLOSE O t / S / 23 r n v /air Arir, Shro/7 k /nfo Head a- - -ºme same *-ºs sº me • * * * * * * * * * * - •= sm - - - ºn as * - - - v.N- ZZ - §§ E-2.2% §: | -" --------4-4 Rºß, ; s * § z * 94% QXX. % A Ç 2 ‘l D = Val/ve Df a me?"er A A = Val/ve Li f f: Ys D-É% * \. y N z VAL VAE OA’E A/ 3.2% & aſ |:2 N43° S Valve Assembly Details Showing Annular Ring Seat, Valve Lift, Seat Bevel, and Size of Port Opening. VAN vanadium—An alloy which gives great strength to steel. vapor capacity is the capacity of air to hold water vapor. Vapor capacity varies from about 3% of a grain per cubic foot at 20° below zero to about 20 grains per cubic foot at 110°. variable means any factor which undergoes a change in values. Lift-drag ratio is a variable whose value changes with angle of attack. Also the coefficients of lift and draq. vºie area represents mechanical means (pilot's control) of changing the area of airfoils while in flight. variable camber represents mechanical means (pilot con- trol) of changing the camber of airfoils while in flight. variable incidence represents mechanical means (pilot con- trol) of changing the angle of incidence with respect to the longitudinal axis while in flight. variable motion is the passage of the center of gravity of a body over equal distances in unequal intervals of time. variation (magnetic)—The angle measured East or West from the true meridian to the magnetic meridian. vaseline is a comparatively thick petroleum product used for packing roller bearings, ball bearings, rocker boxes, etc. Vaseline is sticky and thick, and does not readily flow away from a part unless excessive heating occurs. vector is a straight line indicating the direction by an ar- rowhead and the magnitude of velocities by its length. vegetable oil, commercially for airplane engines, is limited to castor oil, which is produced from the seeds of castor plants. Castor oil will not mix with gasoline, and was used largely in rotary engines. velocity of sound in air equals 1,090 feet per second. venºrhin sheets of wood, either sliced with a knife or SaWęCl. *vent, pressure-relief—A small opening in the covering of the fin of an airship intended to facilitate the equalization of the pressure of the air within the fin with that of the outside air. It also provides an outlet for any gas that may collect in the fin. *Venturi, power — A Venturi tube used to operate gyro- scopic turn indicators and other instruments. *Venturi, speed-indicating—A Venturi tube may be com- bined with a Pitot tube or with a tube giving static pres- sure to form a pressure nozzle which may be used to deterruine the indicated speed of an aircraft through the air. The pressure difference is measured by a suitable gauge. Venturi—-A tube in the barrel of a carburetor with a re- stricted passage designed to increase the velocity of air flow, thereby securing a pressure drop in the throat of the Venturi. *Venturi tube—A short tube with flaring ends and a narrow or constricted section between them, into which a side tube opens. When fluid flows through the Venturi, there is a reduction of pressure in the constricted section, the VER amount of the reduction being a function of the velocity of flow. vertical axis—See AXIS, VERTICAL. “vertical engine—See ENGINE, VERTICAL. vertical interval is the difference in altitude between two successive contour lines on a map. *vertimeter—A device for indicating the rate of rise and fall of an aerostat, usually a special form of statoscope. A rate-of-climb meter serves the same purpose, although of a different form. vibration means to oscillate, shake, quiver, swing back and forth or waver. viscosimeter (Saybolt universal) is a device used to deter- mine the viscosity of oils by measuring the time required for a given quantity of oil at a given temperature to flow through an orifice of given size. visibility—Atmospheric conditions which determine the dis- tance at which objects can be seen. volt—The unit of electrical pressure or potential. voltmeter is an instrument for measuring the voltage drop or potential difference in an electrical circuit. “volume—The volume of the air displaced by the gas used for inflation. *volume, aerodynamic (airship)—The volume of the form which must be driven through the air. Same as “air volume." “volume, air (airship)—The volume of air displaced by the body formed by the outer cover or envelope of an air- ship. It is this volume which enters into aerodynamic computations. See VOLUME, AERODYNAMIC (AIRSHIP). “volume, gas (airship)—The volume of the contained gas. See CAPACITY. volumetric efficiency — The ratio of the amount of fuel vapor taken into a cylinder on the intake stroke to the amount which might be taken in under ideal conditions. *V-type engine—See ENGINE, v-TYPE. *V-wires—The lower lines of the winch suspension of the kite balloon. They meet at the junction piece and form V’s; hence the name. walking beam is a lateral axle in the fuselage. The axle is fitted with rocker arms or horns which receive motion from the control stick and transmit the control motion to the elevators. “walkaway girder—See GIRDER, WALKAway. walnut and mahogany are used extensively in propellers. Their uniformity in finishing and strength gives excellent results for this purpose. “warp–To change the form of a wing by twisting it. Warp- ing is sometimes used to maintain the lateral equilibrium of an airplane. “wash—The disturbance in the air produced by the passage of an airfoil. Also called the “wake" in the general case for any solid body. “washin—Permanent warping of the wing which results in an increase in the angle of attack near the tip. ./ .” A%3a/~~7- A/º saw/// AZ27.725.42 Z//Yeº JA/o/YS - 4 orvée Zza2+ cºe, v3 72/2Z/Y& 42&A 2.745A2) zzº/Z/4 AZ'67& P&oe/"EZ2 The Washin and Washout on a Biplane (Fleet). /Zzar caess seczzar's g \ ; v &s 2= Azzez-Azz-zze- ; \ z zazzarº edge Zs /s2% carozc 2 sº A Azzer A272^e Zayzzº 2 AºAsºº APGE -s/2e. ,’ * £4%22p A2A.Z///s ovy Aézz Aſſºvº 77% ºf cºo-º-; Je;&#d 77/ear, o/c" 7"/44: %52's/£25. A-Zzerz &oeveras 722/12722 77%& 7zºzzº& ÆZºº. Ž Azzºr-saoway as zyaca. A22 4.2” MZºéz Azovoazºvés. Žz&razer 2, 7&E Az7/a/eye’ par zººſe A-Z44.67 Av.7° 7'A'e zºº/z/evº AF267e. Zs-5 o2. a/- 7//ē cºnc. &/º/ 44//yº) Azoreazzaves Aze Azzºzer ea 4/azzees/pe oezºe wºrſe. A/orºzze azoxazººs aze Azzazzºo jºyzzzy --5/rzºzz, acc/axºpº A-Z4.4.4773 Cºy 72/7 a.ºry o 43 c 2.77 ea-7 cº Avray & . Zºe cº/a’ſ/A-7- 7-Ze car rºſe cass.sec. 77 or, as razºycºe/Y7 waZA/ Ac/sezazere surve ºycº Zoa oA- 744: Py/Aycº. The Proportions of a Wing Root Fillet. Wes Azzcºa azvozze nºz W /*acy22. /*eezezzée –27,72/zzzsa. | 7.2/~xcze CA/A3.5/5 - T A Typical Canard Airplane. | 4.42 //2/Yocoz/AEA Typical Examples of Modern Wing Tips. WAS “washout—Permanent warping of a wing which results in a decrease in the angle of attack near the tip. waste gate—The amount of supercharging is controlled by a waste gate, located in the exhaust manifold, which is operated by a lever mounted directly under the spark and throttle control. Moving this lever forward closes the waste gate and increases the amount of supercharging. water (distilled) is the condensed steam from boiling water. The steam will rise and flow through the condenser, leav- ing all impurities, especially metallic particles, in the steaming container. water pump is a pump, usually of the centrifugal impeller type, used to circulate cooling fluids through the water jackets of an engine. *water-recovery apparatus—See APPARATUS, WATER-RECOVERY. “water-recovery condenser—See CONDENSER, WATER-RECOVERY. water vapor—Water in an invisible or gaseous state. watt is the unit of electrical power and is the power due to a current of one ampere under a pressure of one volt. Therefore power (in watts) is the product of volts and amperes. wattmeter is an instrument used to measure the power being cohtinuously expended in an electrical circuit. waves, speed of electrical—See SPEED OF ELECTRICAL WAVES. weather—The state of the atmosphere relative to tempera- ture, humidity and motion over a short period of time and a relatively small area. web is the depth unit of an I-beam section and furnishes the necessary strength for the vertical loads for which beams (spars, etc.) are designed. The sole purpose of the flanges of an I-beam are to keep the web straight in its length dimension. Projections on castings and parts to add strength, and carry bearings and accessories, are also called webs. weight is a measure of the force of the earth's attraction (gravity) upon a body. The standard unit of weight in the United States is one pound. *weight, dischargeable (consumable weight) (airship)—All weight which can be consumed or discharged and still leave the airship in safe operating condition with a speci- fied reserve of fuel, oil, water ballast, and provisions, and her normal crew. *weight, disposable (airship)—All weight other than fixed weights, including dischargeable weights contrasted with fixed weights, q.v. g *weight, empty—The structure, power plant, and fixed equip- ment of an aircraft. Included in this fixed equipment are the water in the radiator and cooling system, all essential instruments and furnishings, fixed electric wiring for light- ing, heating, etc. In the case of the aerostat the amount of ballast which must be carried to assist in making a safe landing must also be included. *weight, fixed (airship)—The weight of the hull machinery and all equipment and parts which are fixed in position and nonconsumable. All constant and nonconsumable WEI weights which an airsi, p would carry arider all conditions of service (British). Liquids in cooling systems of engines are included. *weight, fixed power-plant, for a given airplane—The weight of an engine, including ignition, carburetor, and induction systems complete, propeller and hub, exhaust manifolds, radiator and water, if used, with all interconnecting wires, controls, tanks, and pipes, lubricating-oil temperature regulators, the oil contained in the engine crankcase and the starting gear attached to the engine, but excluding fuel, oil, and engine instruments. *weight per horsepower—The dry weight of an engine di- vided by the rated horsepower. weld (atomic hydrogen arc)—A fusion weld in which the welding heat is obtained by means of an electric arc be- tween two electrodes. In this process the base metal is not in the electrical circuit and the arc can be moved around the same as an acetylene torch. weld (automatic)—A weld made with automatic equipment. weld (butt joint)—A weld joining two members which are butted together, end to end or side to side. weld (fillet)—A weld made at intersections of two surfaces of lap, corner, or tee joints. weld (flush) — A butt weld which shows no excess filler metal at the surface, because the abutting members were beveled to receive the filler metal. weld (fusion)—The union of metal parts in molten state without the application of mechanical pressure or blows. weld (gas)—A fusion weld in which the welding heat is obtained from an acetylene flame burning in oxygen (acetylene torch) or a burning mixture of oxygen and hydrogen. weld (manual)—A weld made by an operator without the use of mechanical equipment. weld (plug)—A weld joining two members by filling in a hole in one of the members. weld (metal arc)—A fusion weld in which the welding heat is obtained by means of an electric arc between the base metal and an electrode. 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WIR main shear—A diagonal wire taking up mean shear loads in the structure of a rigid airship. netting — Diagonal and or circumferential wire netting fitted between the longitudinals over the entire hull of a rigid airship, to transmit the lift of the gas cells to the structure. Sometimes called “gas pressure wires." radial—A wire which extends from an axial fitting at the center of the transverse frame of a rigid airship to a joint of the frame. secondary shear—Additional reinforcing shear wire. “wire, antidrag-A wire designed primarily to resist forces acting parallel to the chord of the wing of an airplane and in the same direction as the direction of flight. It is gen- erally enclosed in the wing. “wire, drag—Any wire or cable designed primarily to resist drag forces: - internal—A drag wire concealed inside the wing. external—A drag wire run from a wing to the fuselage or other part of the airplane. "wire, landing—A wire designed primarily to resist forces in the opposite direction to the normal direction of the lift and to oppose the lift wire and prevent distortion of the structure by an overtightening of those members. Some- times called “antilift” wire. * wire, lift—A wire or cable which transmits the lift on the outer portion of the wing of an airplane in toward the fuselage or nacelle. This wire usually runs from the top of an interplane strut to the bottom of the strut next nearer the fuselage. Sometimes called "flying wire." - wire, safety—A wire used to prevent the turning of nuts, bolts and turnbuckle barrels. "wire, stagger—A wire connecting the upper and lower sur- faces of an airplane and lying in a plane substantially parallel to the plane of symmetry. (Also called “incidence wire.") wood for airplane construction has peculiar virtues and one of the best is the ease with which flaws can be detected. In this connection it is a great mistake to paint wooden parts of an airplane, since varnish or dope will give equal preservation and yet bring out clearly any evidence of defective parts. Wood also has the capacity to absorb vibration. Vibrations produced at a given point in a wooden structure are not readily transmitted to other parts of the structure. . . *wood, laminated—A product formed by gluing or otherwise fastening together a number of laminations of wood with the grain substantially parallel. (Differs from plywood in that in the latter the grain of alternate plies is usually crossed at right angles; also, the plies of the latter are usually made up of veneer.) - work is the result of the application or release of energy. Power is the rate of doing such work. ...' . working stress is the maximum unit stress to which the parts of a structure are to be subjected. WRI wrist pin is the pin in a bearing which joins a connecting rod to a piston. Same as PISTON PIN. *W-type engine—See ENGINE, W-TYPE. yawing—Displacements of the nose of an airplane to the right or left about the vertical axis. yaw, angle of See ANGLE OF YAW. yaw guy—See LINE, YAW. yaw line—See LINE, YAW. yawmeter—An instrument for measuring the angle of yaw. zero (absolute)—273° below Centigrade zero or 459.4° be- low Fahrenheit zero. zenith—The point on the celestial sphere vertically over- head from the observer, usually denoted by the letter Z. zenith distance is the angular distance from a heavenly body to the point directly overhead. The altitude and zenith distances are cºmplementary angles and always total 90°. "zero-lift angle—See ANGLE, ZERO-LIFT. *zero-lift line—A line through the trailing edge of an airfoil section parallel to the direction of the wind when the lift is zero. *zoom—To climb for a short time at an angle greater than that which can be maintained in steady flight, the airplane being carried upward at the expense of its kinetic energy. This term is sometimes used as a noun, to denote any sudden increase in the upward slope of the flight path. Yºr ¥ ¥ * Nomenclature FOR AERONAUTICS AERONAUTIC SYMBOLS 1. FUNDAMENTAL AND DERIVED UNITS Metric English Symbol Abbrevi Abbrevi rev 18- & reV18- Unit tion Unit tion Length- - - - - - l meter------------------ In foot (or mile) - - - - - - - - - ft. (or mi.) Time- - - - - - - - t second----------------- S second (or hour)------- sec. (or hr.) Force----- - - - F weight of 1 kilogram-- - - - kg weight of 1 pound - - - - - lb. Power- - - - - - - P horsepower (metric) - - - - -|- - - - - - - - - - horsepower- - - - - - - - - - - hp. Speed V {: per hour------ k.p.h. miles per hour- - - - - - - - m.p.h. peed - - - - - - - meters per second- - - - - - - In.p.S. feet per second-------- f.p.s. 2. GENERAL SYMBOLS Weight=mg Ö © V, Kinematic viscosity Standard acceleration of gravity=9.80665 p. Density (mass per unit volume) m/s” or 32.1740 ft./sec.” Standard density of dry air, 0.12497 kg-m"-s” at Mass=-H- 15° C. and 760 mm; or 0.002378 lb.-ft. ‘sec.” 9 Specific weight of “standard” air, 1.2255 kg/m" or Moment of inertia=mk”. (Indicate axis of 0.07651 lb./cu. ft. radius of gyration k by proper subscript.) Coefficient of viscosity 3. AERODYNAMIC SYMBOLS Area Area of wing Gap Span Chord Aspect ratio True air speed Dynamic pressure=}ov. Lift, absolute coefficient c-É Drag, absolute coefficient Co- # 0 Profile drag, absolute coefficient cº-# D, Induced drag, absolute coefficient Co-º Parasite drag, absolute coefficient o,-# -Y Cross-wind force, absolute coefficient co-; Resultant force ºw, Angle of setting of wings (relative to thrust line) e Angle of stabilizer setting (relative to thrust line) Resultant moment Resultant angular velocity Reynolds Number, where l is a linear dimension (e.g., for a model airfoil 3 in. chord, 100 mph. normal pressure at 15° C., the cor- responding number is 234,000; or for a model of 10 cm chord, 40 m.p.s., the corresponding number is 274,000) Center-of-pressure coefficient (ratio of distance of c.p. from leading edge to chord length) Angle of attack Angle of downwash Angle of attack, infinite aspect ratio Angle of attack, induced Angle of attack, absolute (measured from zero- lift position) Flight-path angle REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS Y W Nº. - - - Y `s _- T _r Ø t N 6 N. \ ^ § ^ Z Positive directions of axes and angles (forces and moments) are shown by arrows Axis Moment about axis Angle Velocities Force S º S P D S &: ſº g º - to axis e te ym- ositive esigna- | Sym- compo- Designation §. symbol Designation bol direction tion bol |nent along Angular axis) Longitudinal- - - - - X X Rolling----- L Y—--> Z Roll - - - - - q, 14 p Lateral---------- Y Y Pitching----| M Z——— X Pitch_ _ _ | 6 !) Q Normal---. ------ Z Z Yawing- - - - N X---> Y | "Yaw - - - -] p 70) p Absolute coefficients of moment Angle of set of control surface (relative to neutral C.- I, C.- M __N. position), 5. (Indicate surface by proper subscript.) 'TºbS * GCS * qbs (rolling) (pitching) (yawing) 4. PROPELLER Diameter Geometric pitch Pitch ratio Inflow velocity Slipstream velocity Thrust, absolute coefficient cº-ºp. Torque, absolute coefficient cº-ºp. SYMBOLS º P Power, absolute coefficient Cr-ſixty {. 5 5 Speed-power coefficient= #. Efficiency Revolutions per second, r.p.s. Effective helix angle-tan (, V ) Trrº, 5. NUMERICAL RELATIONS 1 hp. = 76.04 kg-m/s=550 ft-lb./sec. 1 metric horsepower=1.0132 hp. 1 m.p.h. =0.4470 m.p.s. 1 m.p.s. =2.2369 m.p.h. 1 lb. =0.4536 kg. 1 kg=2.2046 lb. 1 mi. = 1,609.35 m = 5,280 ft. 1 m =3.2808 ft. A, air pipe to ballonet l, bow cap and stiffeners B, air scoop J, car C, air waive K, drag rope stowage D, balanced surface L., elevator (balanced) E, ballonet M, elevator controls N, elevator-control fairlead O, envelope P, fin, vertical F, ballonet manhole G, ballonet seam H, balionet valve cord | | | d, mean line of the airfoil profile b|c, lower camber c/4, aerodynamic center (quarter. Q, fin, horizontal R, gas manhole S, gas valve T, hand rail U, handling lines V, horn (rudder, elevator) W, inflation sleeve X, Inspection window J/of ..' r * . ‘. . Wºng equipped with leading-edge slof, \, 'ss, `, infercepfor, ond s/offed aſſeron. º, `-S, Spoiſer... S- Moin wing Wing equipped with spoiler and F.rise oileron FIGURE 1.--Wing equipped with special control devices. * % º ** | - Troiſing edge 2. | sº Ø % %%2. alc, upper camber chord point) f, profile thickness FIGURE 2,-Dimensions of an airfoil profile. m/c, mean camber c, chord length 2P Frg URE 3,-A nonrigid airship. Y, martingales Z, moorl ng line A’, rip cord B’, rip panel C’, rudder (balanced) D’, rudder controls E’, suspension wires, car F’, valve controls A, alr duct B, alr valve C, automatic and manual valve (gas) D, axial suspension band E, balanced surface F, ballast (water) G, ballonet H, ballonet blower !, bow cap J, bow stiffeners K, car (control and power) L, catenary M, climbing shaft N, Control cables Z, mooring line O, drag rope (stowage) A’, observation platform P, elevator (balanced) B’, outer cover Q, fin (horizontal) C’, pneumatic bumper bag R, fin (vertical) D', radiator S, gas cell E’, rudder (balanced) T, gasoline tank F’, suspension wires U, gland G", transverse diaphragm V, handling lines H’, valve hood W, inflation sleeve I’, ventilator X, keel, continuous from bow to stern J', wall of gas cell under partial de- (articulated) flation Y, longitudinal diaphragm FIGURE 4.—A semirigid airship, REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS |H Z • |-- / 5 J – - - - - - - - - º- —l-ºr- - : ar *- * A, alleron B, angle of landing C, angle of stablilzer setting D, angle of wing setting E, antidrag wires F, balanced surface G, chord H, cockpit l, control stick J, control wires K, cowling L, decalage M, dihedral angle N, drag strut O, drag wires, external P, drag wires, Internal Q, elevator R, fin S, fire wall T, fuselage U, gap V, horn W, inspection window X, landing gear Y, landing wires Z, leading edge A’, lift wires B', longeron C’, overhang D’, propeller blade E’, propeller boss F’, propeller hub G’, propeller root H', propeller tipping I’, rudder J’, rudder bar K’, shock absorber L', span M’, spinner N", stabllizer O', stagger P’, stagger wires Q’, stay R’, strut S’, sweepback T', tail skid U’, trailing edge V’, wing rib W’, wing rib, former X’, wing spar Y’, wing tip -* ºr * ºotteſduțe ity – Q aſinoiſ •@, H < (€/xo••••••YT_→T__）~~~~}}Go)| /420//p_）~ ~5) - 6ørøa -/a>awcy „op-Jouyo�syxo ·r·/?6tjoy__）~~~~/\ȚĂ -/a>/>do-º Pu// → CO2~~~~ 6uraa Jadoºn================：：=Tºr=~~~sæ**$$=Ū),){| szty, c/)AO AP-foly> o/ /º/o-doo' sup7.^§ĒFĒ\\ /S/7_////•=============№¡№F3Tl| 3 /o acu/7→======F****jºjn„.^^;; ``s）. --~~*~#~$№R]PŮSOE§||\|.\|,5) <！---j.， |-0.-^^ !! ``s, 21.*¿?ſaeſiſ||*ſvĀTU，} |-•.••<<*#FĒ，¿jº><！--#-#.^ ^ ）* )*|�A 4–}- -->}} ！= ！= *） ） &= ==， ！= æ\！\!\!\！\！\！-1;:ZO ！№.±，±，±，±， †#-----Ę=|#|Ē| / | „WN bºf4 ! •{№NýLSŹí � …26：aaJødda yo2ºººo-|\，\!Œ2|- ŹNŹŃ ZŁOŻº szºsz， ºg S Verfica/ echor, º A A, balance and model support G, motor B, entrance cone H, propeller C, exit cone l, return passage D, guide vanes J, slots E, honeycomb K, static plate F, model FIGURE 7.--Diagram of a wind tunnel. SOIJLQV NORIGIV （IOH GIGIJALIWIWO'O XHOSHA (IV TIVNOIJLWN JÁHOd3I8I =s* * \ A, a wing-o'er F, an Immelman turn B, a snap roll G, a spiral C, a chandelle H, a normal spin D, an aileron ro'ſ !, a normal loop E, a split S Ficure 8–Airpliſhe mareuvers. NOMENCLATURE FOR AERONAUTICS •º S f { \ Tº - ~ | | * * Sz-, - --&#--4 * f \ G r il s: Z Æ / ; ; ** – 5× N.J.-2 F, drag axis G, flight path H, lift, dynamic !, positive ſlft axis J, resultant force A, angle of attack B, center of gravity C, center of pressure D, direction of relative wind E, drag FIGURE 9.—Liſt and drag axes, C, lateral axis D, positive direction of roll A, angle of roll B, c.g. and long!tudinal axis FIGURE 10.-Rolling. A, angle of sldeslip B, center of gravity C. c.g. and normal axis. Z ,” T se * * \ \ sº- i = * * * * = smº m = D, direction of motion of aircraft E, longitudlnal axis Figure 11.-Sideslipping. A, angle of pitch D, longitudinal axis B, c.g. and lateral axis E, positive direction of pitch C, direction of relative wind F, propeller thrust FIGURE 12.-Pitching. | * A, c.g. and normal axis B, direction of relative wind * Af C, longitudlnal axis D, positive direction of yaw FIGURE 13.-Yawing.