MPcCfVL-l-l"^ AEE No. L5F3O NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WARTIME REPORT ORIGINALLY ISSUED Aiigaet 19^5 as Advaace Eestrlcted Report L5F3O HINGE MOMEKTS OF SEALED -INTEENAL -BALANCE AERANGEEMEKTS FOR CONTROL SURFACES I - THEORETICAL INVESTIGATION By Harry E . Murray and Mary A . Erwln Langley Memorial Aeronautical Laboratory Langley Field, Va. UNiVcriSll Y or plOHium DOCUMENTS DEPARTMENT 120 MARSTON SCIENCE LIBRARY RO. BOX 117011 QMNESVILLE, FL 3251 1 -701 1 US^ NACA WASHINGTON NACA W/^JITIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance research results to an authorized group requiring them for the war effort. They were pre- viously held under a security status but are now unclassified. Some of these reports were not tech- nically edited. All have been reproduced without change in order to expedite general distribution. L - I7U Digitized by tine Internet Arclnive in 2011 witln funding from University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation http://www.archive.org/details/hingemomentsoflang NACA ARR Ho. L5P50 NATIOT'^^AT. AT-,viSrRY CCf'Tr^.iITTEE FOR AERONAUTICS ADVANCE RESTRICTED REPORT HINGE MOIWNTS OP SE AL ED -INTERN AT; - BAL ANCE • ARRANGEIllENTS FOR CONTROL SURF./JCES I ■ - T?IEORETIC AL INVESTIGATION By Harry E. Murray and Mary A. Erwin SUMMARY The results of s tl-ieoreticel analysis of the hinge- monent characteristics of various sealed-internal-balance arrangements for control surfaces are -oresented. The analysis considered overha^ngs sealed to various types of wing strijcture by flexible seals spanning gaps of various v/ldths or sealed to the wing structure by a flexible system of linked plates. Leakage was not considered; the seal was assuraed to extend the full spanwise length of the control surface^ The effect of the developed width of the flexible seal and of the georrietry of the structure to which the seal was anchored was investigated, as well as the effect of the gap v.'idth that is sealed. The results of the investigation indicated that the most nearly linear control-surface hinge-moment charac- teristics can probably be obtained from a flexible seal over a narrow gap (about 0.1 of the overhang chord), which is so Installed that the motion of the seal is restricted to a region behind the point of attachment of the seal to the wing structure. Control-surface hinge moments that tend to be high at large deflections and' low or over- balanced at small deflections will result if a very narrow seal is used. INTRODUCTION Experimental data on control surfaces having various arrangements of sealed internal balances have been col- lected and a correlation has been made of the hinge -mxoment characteristics for small deflections (reference 1) . The data used in this correlation were for balances consisting I'lACA ARR No. L5F30 of an overhanfc .sealed to a wing structure by a flexible seal made of thin rubber or fabric. The effect of the overhang-seal combinations was assumed to be the same as that of an effective, overhang chord equal to the chord of the actual overhang plus one-half the width of the gap closed by the flexible seal. Obviously, such an assump- tion could be expected at best to account approximately only for the effect of the balance configuration near zero deflection of the control surface and to neglect the effects of variations of the dimensions of the balance chamber, the developed seal width, and large control- surface deflections. Because seeled internal balances are coming Into rather wide use on the closely balanced control surfaces of high-soeed alr-olanes, a systematic investigation has been made by the Stability Research Division of the NACA to determine the characteristics of such balances. The results of the investigation provided data that may be used in obtaining better original designs of sealed internally balanced control surfaces and that allow a more accurate estimate of tho change in hinge-m.oment characteristics associated with modifications of the ba]. ance arrangement. The investigation included both a theoretical and an experimental study. The theoretical investigation, which is presented herein, has as its object the isolation of the most important variables affecting the characteristics of sealed balances and the determination of the effects of as many of these variables as possible. The theoretical analysis was supplemented by an experimental study (ref- erence 2), which served as a check on the theory and pro- duced data on many im.portant details not adapted to theoretical procedure. For the general investigation, two types of internal balance were considered, typical installations of which are shov/n in figure 1. In one case the overhang was con- sidered to be connected to the wing structure by a flexi- ble seal capable of sustaining only tensile stress; whereas In the other case the seal was a flexible s7/stem of linked pi ates . The theoretical analysis given herein presents results showing the effects of variations of gap width, developed' seal width, and shape of wing structure to which the seal is attached for the flexible sealed balance and the effect MCA ARR No. LSFJO of varying the length of the seal plate in a linked- plate balance consisting of two plates. SYMBOLS. '-'0 ip h,k Ln 5i. R 3 V 5 Mb overhang chord pi-'essure difference across balance coordinates referred to origin at overhang hinge axis coordinates of seel ai''c center vertical clearance required for seal to develop moments presented in figures 9 to 11, fraction of overhang chord v/idth of gap between points of attachment of seal when 5v) = 0°, fraction of overhang chord overhang deflection, degrees (See fig. 2 for sign conventions . ) radius of seal arc mass density of air, slugs per cubic foot tensile force in fabric se.9l per unit span pressure coefficient across balance — ^ .A 7 free-stream velocity /l 2^ free-stream dynamic pressure f — pV j total balance moment of balance system of unit span volume of balance system, at deflection 5^ control-surface deflection, degrees m.oment of overhang of unit scan ( -— -b seal moment; incremental hinge moment resulting from seal of unit so an J+ NAGA ARR Mo. L5B'30 t thickness of ovarhang at hinge a:>:ls rric sesl-moment rstio for overhang having t = (Mg/l'Ih) s developed seal width, fraction of overhang chord AC]^ increment of section hinge-moment coefficient resulting from balance C£ control-surface chord Cg aileron chord ^ leading-erlge angle of overhang c airfoil chord h control-surface section hinge m.oment 0^1 section hinge-moment coefficient (h/qcf ) a angle of attack, degrees A^LAI,YSIS Methods The present theoi^etical analysis v^rps an investigation of the characteristics of variou.s configurations of sealed internal balances. These configurations consist mainly of the tv;o types illustrated in figure 1: (1) overhang balances serled to the wing structure by flexible m.aterial capable of sustaining only tensile stresses and (2) over- hang balances sealed to the vifing structure by a flexible system, of linked plates.' The moments resulting frcmi the types of balance shewn in figure 1 v;ere determined by the follow'ing two methods: (1) ■Resolution of forces - The method of the reso- lution of forces consists of finding the forces exerted by each part of the balance system as a result of a pressure difference across these parts. The m.oments of these forces about the control-surface hinge are then added to got the total moment of the balance system. NACA ARR No. L5F30 (2) Volume displacement - The method of volume dis- placement consists of finding the rate of change of volume swept by the balance with deflection. The moment of the balance is then Mt Vd6/ AP 1) Overhang Balance with Flexible Seal The configurations investigated are shown in figures 3" to 5* The m^oments of such balances can be v.'ritten as the sumj of the moment resulting from the over- hang and that resulting from the seal; therefore. M B 2 Cb V2; + M, ;2) The raom.ent exerted by the seal can be expressed in term.s of the seal-moment ratio m. Then 3 2 2 , Ap 2 ,+ . 2 ^b -^^s (5) or J in terms of an increment of hinge-moment coefficient, P^ /cb\2 Acu = -^ I — h 2 \Cf/ v2 'v2ci + m. ik) In order to obtain numerical values for Ac h' an investigation was m^ade of the variation of the seal-moment ratio m.g with the two Important balance dimensions - the width of the gap to be sealed and the developed width of the seal. Such variations were investigated for seals attached at the leading edges to the following backplates, which simulate three representative types of v/ing structure KACA ARR No. L5F50 (1) Forizontal-line backplate (fig. 5) (2) ''/'ertic al-line backplate (fig. [|.) (3) Circular-arc backplate (fig. 5) The flexible setls analysed were assumed to be non- porous, inextensiblc, oerfectly flexible, and weirhtless. These assuirptions iinoly that the unrestrained part of the seal forms an arc of a circle and has a tensile force, per unit span, -'f T = ^x)r acting every'.vhere tangent to the arc. The n-icrnents resulting from these seals arise either from the tensile stress in the seal (figs. 3* hi ^) t and 5(s))or from the seal lying along and equalizing the pressure over part of the overhang (figs. U-ik) and ^jih) ). In order to apply the resolution-of-f orces method to the seals shown in figures 3> ^(s), and 5(^)> "the radius of the seal arc and the point at which the seal leaves the backplate v.'ere determined. The investigation showed these unknowns to be related to the other variables in the balance system as indicated by the equations presented in appendix A. After these unknowns had been determined as suggested in apcendnx A, the balance systems v/ere con- structed as shown in figures 3> ''+( a) ^ ^'^d 5(s)' The seal m.oment was then computed from the seal tension and the lever arm, which was measured from, the construction. If the resolution-of-f orces method is applied to the seals shown in figures I|.(b) and '^(h) , the lever arm of the tensile force in the seal is zero. The reduction in effective overhang chord caused by such seals was equal to the amount of overhang covered by the seal; this ainount can be determined as explained in appendix B. In order to apoly the volume-displ acem.ent method to the seals shown in figures 3* k-i ^) > snd 5(s)> the balance system v/as again constructed graphically. The area swept by the seal, which equals the volume for a unit span, was then mechanically integrated and plotted against flap deflection. The slopes of this curve could then be esti- mated for use in the formula for Mg. Because of the difficulty of estimating the slopes from these curves, the volume-displacement method proved to be the less accurate of the tv/o methods. If the effective-overhang reduction corresponding to the seals of figures i4.(b) and 5(t)) is found "by the method of aopendix B, the moment resulting from the seal can be determined in terms of the volume swept by the effective-overhang reduction. NACA ARR No. L5F50 Pressm^e-dlstrlbutlcn data showed that, at high angles of attack, the deflection of a control siorface from -o° to -12° may hs necessary before the press-ure across the seal changes sign. At such deflections the seal is extended in a direction opposite that of the overhang. This deflection range corresponds to the negative values of the overhang deflection S-v-, . (See fig. 2.) As soon as the pressure changes sign, the seal blows across the gap and 5v, is again positive. In order to investigate this phenomenon, seal moments were computed for values of 5^ from -12° to 20° except in cases of very small gaps, for which the computation of seal moments for the entire negative range was sometimes Impractical. Overhang Balance with Linked-Plate Seal 6 and 7 show linked-plate balances consisting of two and three hinged plates, respectively. The total moment of the balance system can again be represented by equation (5) in which the seal moment is the moment of all parts of this balance except the moment of the overhang rigidly attached to the control surface. As indicated in appendix C, the mom^ents exerted by such balances can be determined by both the resolutlon-of -forces and the volum.e- displacement methods. RESULTS AND DISCUSSION Aui ' investigation of the seal-m.oment characteristics of the various seal arrangements was made by the resolution- of-forces method and was checked by the volume-displacement method. Only the moment characteristics of the seals are presented. The effects of the entire balance system can be obtained from the seal-moment characteristics by m^eans of equation (I4-). Figure 8 presents the characteristics of flexible seals for various gaps as given by the approximate formula of reference 1. Hinge moments of internally balanced control surfaces normally becom.e heavy at large deflections as a result of a decrease In 6Ppy6 5 with deflection. In order to offset somewhat the effect of a decrease in dPp^/oS vi/lth deflec- tion and to give the most nearly linear control-surface 8 NACA ARR No. L5F30 hinge moments, tm^/^&^i shoulc' have a positive value. {A positive value of 6ms/6 5b that Increased with deflection would be even more desirable but generally cannot be obtained.) This positive value of 6ms/dS]3 may be considered favorable inasmuch as linear or nearly linear control-surface hinge moments, although not altogether necessary, are generally desirable. Flexible Seels The characteristics of the flexible seals are pre- sented in figures 9 to 11 for the horizontal-line, vertical- line, and circular-arc backplates. A comparison of these figures with figure 8 shov/s that, in general, large errors in the seal moments may result from, the use of the approxi- mate formula. Corresponding large errors can also be expected in control-surface hinge raom.ents estimated by the approximate formula, except when the seal effect is sm:all relative to the total balance moment. The seal character- istics shown In figures 9 to 11 c £n be discussed best in terms of the following seal variables: gap width, developed seal width, type of backolste, and type of over- hang. Effect of gap width .- The effect of changes in gap width can be seen best by reference to the curves for s = 0.6 (figs. 9 to 11) for any backplate. These curves indicate that an increase in gap width for a seal of con- stant width increases the seal moment at small positive deflections and decreases the seal moment at large posi- tive deflections; the effect is, therefore, a change in 6ms/o5-5 in the negative or unfavorable direction. If the most nearly linear control-surface hinge-m.oment character- istics over the entire deflection range are desired, small gaps of the order of g = 0.1 should be used. In terms of control-surface hinge moments, Increasing the gap width tends to result in high control-surface hinge moments at large control-surface deflections and low or overbalanced moments at small control-surface deflections. Effect of developed seal v>'idth .- Figures 9 to 11 indicate that decreasing the developed seal width tends to change dm^/fe 5v, in the negative direction, a change which is unfavorable. This effect should be the most Important single consideration in the design of a flexible MCA ARR TTo. L^^FJO sealed balance. The seal must be sufficiently long that it does not become taut (see fig. 12 ) within the usable deflecticn range. The seal shewn in figure 12 has s vei'y large radius of arc; therefore, a very large tensile force is to be expected. Because this force is so directed as to unbalance the control surface, a sharp control -surf ace hinge-moment increase is to be expected at large deflec- tions . Very wide seals contact the balance-chamber boundaries at large deflections. A reduction of the seal moment then results at large _def lections and this reduction also tends to change dra^/d&-^ in the negative or unfavorable direc- tion. Because of the difficulties involved in the analy- sis of the seel effect after the seal has contacted a balance-chamber boundary, such effects have been determined experimentally (reference 2). Figures 13 to 15, however, were included to indicate the ranges of gsp, seal width, and deflection in v/hich the seal m^oments presented in figures 9 to 11 can be expected to be valid if the balance- chamber depth is known. Effec t of backp lates . - The effect on the seal moments of the three backplates investigated is shown in figure l6. Figure lb (a) shows that, for a small gap (g = 0.1), the horizontal-line backplate tends to give large balance moments st small deflections and small balance moments at large deflections. The horizontal-line backplate therefore tends to result in an unfavorable value of dmg/ibS]-, ana should be avoided. The vertical-line and circular-arc backplates, v^rhich restrain the motion of the seal to a region behind the point of attachment of the seal to the wing structure and give a favorable vslue of 6mg/6 5|3, should be used. Increasing the gap width tends to reduce the difference between the seal -moment characteristics of the three backplates as indicated by figure l6(b), which shews, seal-morent characteristics for g = 0.5- These backplate effects are summarized for- only one representa- tive seal width, since other widths v/ould give variations similar in character but differing somewhat in magnitude. Effect of ov erhang shape .- If the overhang is changed from, the thin line assumed in the anal7/sis to a triangular c^^oss section as shown in figure 17, the angle at the point of attachm.ent of the seal can have a value up to [(.0° and yet effect no change in the seal moments presented in 10 NACA ARR No. L^FJO figures 9 to 11 for positive deflections and for gaps of about g = 0.15 ^^ larger. . This result is obtained b"C£use the added overhang thickness does not touch the seal. A rather l?rge range of overhang shapes therefore seems to exist, for which the presented seal -moment characteristics v/ill be altered little if any. Linked-Plate Seals The possibility of improving the hinge-m.oment charac- teristics of control surfaces having lim.ited overhang chords by using llnked-plate seals such as illustrated in figures 6 and 7 l©"^ to en investigation of such seals. Figure l8 indicates that the linked-plate seal consisting of tv;'o oletes [txa. 6) exhibits an unfavorable value of 'rrig/de b- Another problem Is the practical consideration of preventing leakage around the moving leading edge cf the seal plate. One method of oreventing leakage is to use a third plate as shown in figure 7* This third plate may be sm.all with respect to both the original seal plate and the overhang so that the seal mom.ents still approxi- mate those of figure l8. If more exact characteristics of the three-plate balance are desired, the m.ethod of aopendix C can be used. EXAJ^LE In order to show how the characteristics o Internally balanced control surface can be obta these of the sealed unbalanced surface and to i magnitude of some of the effects about which co have ali'eady been drawn, the effects of two bal figurations on the hinge-m.oment characteristics aileron section shown in figure 19 have been de The characteristics of the unbalanced aileron s shown In figure 20. Prom equation (lj_) the incr hinge-mom.ent coefficients were computed for tv/o having vertical-line backplates and the follov/i dimensions : f a sealed ined from ndicate the nclusions ance con- of the termined. ectlon ere omental balances ng Configuration i c-^/ca 1 0.1^17 2 .521 0.5 0.7 .6 NACA ARR No. L^FJO H The effective overhang as given by the approximate formula is cb = 0.S21 for both configurations. The hinge-moment characteristics of the balanced aileron are therefore the same for either configuration according to the approximate formula and are shown in figure 20. The section shown in figure 19 has L-i ~ O.5 in the region in which the seal is located. Inasmuch as fig- ure ll|-(d) indicates that a value of Lx ~ 0-3k- is required with configuration 1 and Lx ~ O.I|-6 with configuration 2 for a deflection range of ±20°, ample space is provided for the seal to develoo the moments indicated by fig- ures 10(a) and 10(f). In order to show the computation orocedure, the calcu- lations of the incremental hinge moments for configuration 1 are presented. Equation (I4.) was written as follows to represent configuration 1: Ac^ = PR(o.oe68) ( 0.7975 + ^s) Table I shows the computations required for obtaining hinge moments of the balanced aileron from, this equation. A sim-ilar procedure is used for configuration 2 and for the approximate solution. The computed characteristics of both configurations are shown in figure 20. This figure Indicates that the lajT'ge gap and rather short seal of configuration 1 result in heavy hinge moments at large deflections and that the approximate rule does not properly represent this configu- ration. It can also be seen that the approximate rule represents configuration 2 reasonably well at large deflections but leads to considerable error at small deflections when the seal lies along part of the overhang. CONCLUSIONS The hinge-moment characteristics of various ■ arrange- ments of sealed internal balances were investigated 12 ::aca arr no. l5F30 theoreticslly . The results of the investlgstion indicated the following conclusions: 1. Increasing the gap width for a seal of constant width or decreasing the developed seal width tends to result in high control-surface hinge moments at large def].ectlcns and low or overbalanced moments at small deflections . 2. Eackplates that restrain the motion of the seal to a region behind the ooint of attachjnent of the seal to the wing structure probably give the most nearly linear control-surface characteristics . 3. Varying the cross section of the overhang from that of a thin plate presents no im.portant aerodynamic disadvantage and, if such a change is desired for struc- tural reasons, s considerable range of design is available in which the seal mom:ents are unaltered. Langley Memorial National Ad Langley rial Aeronautical Laboratory ,1 Advisory Comm.ittee for .Aeronautics .ngley Field, Va. April JO, 19lj-5 FACA ARR No. L5F50 13 APPENDIX A EQUATIONS CBT.ilNED 'JTd^.}^ NO P /SRT OP SEAL LIES AG.AIN3T OVERHANG The fo?_lowing equations relate the quantities involved in fixing the position of the seal arc when no oart of the seal lies against the overhang: (1) For horizontal-line backplate (fig. 5)? 2r sm ^ -^ r^ ^=- + (x-^ - X2) dr T - — C^l - h)2 ^ yi (2) For vertical-line baclcplate (fig. li( a) ), s = ^r • -1 7(^2 - ^1)^ + (^ - yi)^. . sm ' ^ ^^^ — ^ + 2r k 1 r = — 2 (X2 - .,; . Ul-^il An - A •- (3) For circular-arc backplate \vith center st overhang hinge axis (fig. '^{a)), o ■ -1 aA^ - ^1) + ( 7 5 ~ yi) ^ . -1 Zi 2r sm ■ --^^ — -^ — ^ — ^ -• ••+ xp sm — -^ 2r ^ ^2 r = X' 1 - - 2 1 ^ =b2 - -2^ \ V-1^5 + Tijj - xj^y li; NACA ARR Wo. L^FJO In these formulas, the first term represents the length of sesl in a free arc and the second term represents the length of seel lying against the backplate. If conditions ai'e such that no part of the seal lies against the back- plate, all three cases may be solved by s = 2r sin' ■1 \A.^i - ^2 )^ + Ui - ^zf 2r If these relationships are subject to a practical condition - for example, requiring that the seal width remain constant - the radius of seal arc and the location of the point at which the seal leaves the backplate should be determiined in order that the system may be constructed for a graphical tyoe of solution. None of the equations could be solved for any quantity other than s, however, because of the inverse trigonomrtric functions involved; curves of the equations were therefore plotted and the necessary values were read from the curves. NACA ARR No. L^P^O 15 EQUATIONS OBTAINED 'A'FEN ? mT OF SEAL IIES AGAINST OVERHANG The following equations relate quantities Involved in fixing the position of the seal sj-c when pai^t of the seal lies against the overhang. (The meaning of symbols used in these equations but not defined in the list of symbols can be obtained from figures 4(b) and 5(h).) (1) For horizontal-line backplate, the equations are omitted since the case is of little practical importance. (2) For vertical-line backplate (fig. [[.(b)). / s = 270 ,tan 90^ - 6b 57.5 + (d + xo tan 6-^) + C^ - ^b + X' >ec 0^) (5) For circular-arc backplate v.dth center at overnang hinge axis (fig. 5(t)}), s = r(270" - p) 57.3 + P(cb + E) ^ 5b(cb + g) 57.5 57-5 + d P = tan" (Cg + g) - {c^ + g){l - cos p) - r cos p d = [c-^ + g)(l - cos p] + r cos p - g In these formulas the first term represents the width of seal in a free arc; the second term, the width of seal l6 NaCA ARR No. L5P50 lying along the b?ckplate; and the third term, tho width of seal lying &long the overhang. In order to find the amount of overhang covered b:;- the seal, the distance d must be known. This quantity can most conveniently be found if d is plotted against the seal width s for various overhang deflections. /SToroorlate values can then be read from the curves. MCA ARR Wo. L^F30 1? AFPEimiy c APFIICATTCN OF JI^THCDS TO LIN:-T:D-:pL ATE 3 ^L ALICES A link.ed-plate balance consisting of two hinged plates is shov^n in figure 6(a}. Figure 6(b) shows the force breakdo\vn of the system for the resolution-of-f orces method. (The symbols used in this appendix and not defined in the list of symbols can be obtained from figures 6 and 7«) The moments exerted are as follows: The morent of plate LM is Ap k^ The moment of normal force F-.,- is A? BA 2 L cos Ov, ,' '-r sin^S-^ - - sin^S^I 1 J The moment of axial force F. is Ap A- o A o in"-f^-h + — cos 5>, sin 5, 3 ■•' ' 1 - — I sm Cy. M„= /iD BA B 2 4 \2 p cos f'-j. - 2 I—-J cos b-^ sin'^Si^ - ^2i^ sin^5-b sin 5i Ap A" 18 NACA ARR No. L^FJO For the volTime-displacement method, the voliiine enclosed by plates A sjid 3 Is 2 ^ / V - r-sin 25>, + ^ sin 5^, /l f— 1 sm 6, Vb/ Then _dv_ _ AE d5b = 2 cos 5^ - 2( a\2 o =-j cos 5^ sin'^5-[3 I /- M'^2 . 2. - ^(1) -^ A^ . „ dv _ ip AB Mp = AP -^-r- = — - — B d5-[-, 2 cos 5b - 2 /a\2 2 6vi sin 5, r ■A - 2 sin 5, D Q 1 A p J ,2 In terms of seal-moment retio, with plate B con- sidered as the seal. m B A cos 5i 1 - 2l|j sln^S^ ,/l - (ff Mn2, 2|-V^in^5, In order to solve the three-plate 1, inked balance shown in figure J{ a) , the system should be broken down as shown in fiparo ^{h): the normal force Fjr and the axial force p. ezerted by plate LM and plate KL at joint L should then be determined. Since the dimensions of the plates are known, Fa can be expressed as NACA ARR No. L5F50 19 P 1 m cos (e - 9C°) + LM tan (9 90^) The value of 'N depends only on the length of plate LM and the pressure difference so that p. = f « The vector forces P. and P„ can be added graphi- cally as shown In figure Jih) to find the resultant force and its lever arm, the product of which is the moment of plates LM and IW. . The sum of this mom.ent and the moment of plate KL is the total moment of the system, which can then be checked by the volume-displacement method. 20 NAG A ARR No. L5F50 REF^RENCSS 1. Rop-fillo, F. M., and Lowry, John G.: Resume of Data for Internally Balanced Ailerons. NAC^ RB, March 191^5. 2. Fischel, Jack: Hinge Moments of Sealed-Internsl- Balance Arrangements for Control Surfaces. II - Exper-imental Investigation of Fabric Seals in the Presence of Thin-Plate Overhang-s, NACA ARR No. L5F30a, l^k3 n NACA ARR No. L5F30 21 o o o [a o a:: O o oc u o •I CD ^ „.-^ T3CD © — CO -J- OS lTS ITS (M o O r-l <7S OS r^ OS t— CM CO CTS US US 00 O . l-~- C3 r-l LTS CM l^ so CO r\i SO rH -d- us CM r-l CM KS SO -d- NS *— ^ ^ C + f\J c^ V~ -^ CM 8 O o rH r^ CM NS ^ so cr) O CM -d- I^ r-l ON o a r-l i-H o o O o o o O O o o O o r-l r-l r-l r-l CM f-H CO w • o • • • • • 1 1 1 • 1 • • • 1 1 • 1 • 1 • 1 « 1 1 • • 1 1 ^ ■d ro> ro« O SO KS _-t CM t^ o 00 us rH CO o CTs o SO NS O ^^ Xi a) o f\J l^ o CM l/S r-l ITS o O O rH r-l r-l rH CM ITN ON ITS u^ ITS LfS US LfS us US US us us US irs us irs us US us - — . t— C- t^ t— l^ t^ CO OS o - -d- i-H 1^ rH NS C\l us 03 — c^+ J- t- ON o r-l r-l CM CM CM t ^— vO VO so NN UJ ^ r-l CM o O r\i US US so -I- r-l 1^ NS 1^ r-l NS lr^ CO ^- ITN ITN LTN --t ^r^ CM rH O rH CM NS J- US -o SO r- r- CO CO O X t\J o " • O • O 1 o 1 o 1 O • O O O o • O O O • o O • o • o o o * • o o O o o o O o O o O o o o o o o o o o o CJ o o C3 r^ CM res u-\ U) o NS CM r-l o ( ) ( ) o O us ^-^ 01 _rt KN -ct r\l CO CM ir\ O- O C5 OS ^- US CM CO CM d- NN ^ rH -^ e o rH OJ NS, NS -d- _d- -d- US US -d- -d- -d- J- NS NS CM r-l O NS o 1 1 1 ^-^ 43 W CO vX) -d- f\l O CD so --1- CM O CM -d- so CO O CM -d- SO CO o K> O IE rH t~l rH r-l rH 1 r-l r-l r-l rH r-l CM ^"^ X) o tn LTS r\l o O KS o US t0 ^ ^ I I I I N NACA ARR No. L5F30 Fig. 4a, b I » ■ (O^O) (oj Sgo/ c/^cy/-" of //♦ya/?ey . NATIONAL ADVISORY COMMITTEE FOR AERONAUTICi /^/au/^G ■^. - //7/^^/y (o) /^c^/a/Ttrs cfr-r'a/?os/7?(S/7r. NATIONAL ADVISORY COMMITTEE FOR AEeONAUna Fig. 7a, b NACA ARR No. L5F30 Y /° ('(^J /So/a'/^c& Y ///r?^i;^ ^ -.j;^---:-., lb-,- ^^ "■, , 7 X ^ v.t'-f ; '^ '^ ^ m^- — --, 3[ ^, "^ Ji^ ^ ^ ^^ :^ W ^'*y\ ^ \ * ^^\ ^-- j S \ i ^ M- \ S \ "- ^^ V ^ ^ ^- .-zZt S ^^ <:2l __ _ v S - % S t_-^ ] T (bjg-o./ -IZ -6 Overhang def/ect/on , 6k , deg ,„,on»l aov.sorv (P^ n^O 4- {T ) g--0-5 ■ COMMITTEE FO. «E»0N.UT1CS Figure 9- floment charocter/5tic5 of flexible 6ea/5 with honzontal-hne bacKplafe^. NACA ARR No. L5F20 Fig. 10a- f •Sao/ cufetfh,s\ 0^-[ J (. r ■5; ^ '^ / « •s \ \ , ^ fh.s' ^ ' Oi ^ ' ^ / , -^ ^ ■ -^ ^ ' -■^.4. J {aj g'O . •Sso/ u/iaf^ t s ./o __ - _- T^t-- — ^ ^ ^ "^I't" ^ (7flt- ^-'^-t" ^I't' ^ 6/0 ^: ,^--'^^^' N'^ - 5^ ,---^'%'' L " rr tdXWjauI \ o _ - - _ - r- r' /)/?- - _ '^^ . [- (b)g ^o.i s [cjg- o.s . (d) g = 0.3 3£ 1 1 1 1 1 1 1 [ 1 1 1 1 1 1 I 1 M 1 1 1 n r ■'^° . ----- ■■ [ TT 1 1 1 1 1 - .Z4 -- ; = -#r = = -32 ^ — = ^^"' " ^ -- I- -" "^ -' .^ '■ ""^ .. CAC-' s ----.''" -'■^-' "nJ-i'' '"•'' ^^ 5. 24- , = -;■='' ^^ \ ■ ° -. -<-' .-■' ^-Z Prf rs?1^ N H -vxvri ^ "i ■= - ^^ X ^-^ \' ^ =-' -'^' IE -■=' \ /O/? "" ^ '' -^ J-Z If,' ^ itV - ■'* _ "i. - - ^ -^ ^ it ~3 . ^-^ X":" " u 'Ai \'- OB \ -^ ^- .ua J X - -- S X L - T :i?(9.-_ : :::__:__:±::r o .. — . _ : - 46 .40 .32 .Z4 .16 .08 -IZ -e -=>^ /£ :S ^: N ^ \ 2jD ~ ~ « ^_ 1 { 1 1 1 I 1 1 >fn "" "^^ ^ "^. ^ ' ' ^^ ^^ ^ ^CiS- N ^^ ^J: -^^ s^ ^^ : .^w s s ^^. \ \as>-- \. 22 \ OP - ^ ^ V V \ 5 ^ S \ . ^ Si V A -V ^ ajs- ^ - ? -V \ \ t-II no \ — ua .r_ O. - _ - _i:; -IZ -6-4 1- 8 IZ 16 ZO Overhang def/ect/on , Sa , deo , (e)g--o.4. ^ z?> y (f)g=o.5. Figure 10.- flomenf characters t/c3 of flexible seals luifh verticai- ////« UUl..^/^ fJ/U/ki^ . COMMITTEE FM «£«0««UTICS Fig. lla-f NACA ARR No. L5F30 -OQ -.lb -.^4 " - " ~ "" ~ — . o^ - -- -- !0 ^ ^ " - ?Su? ^ -1 ;- ■ ''' _ ^ 76 .ae ' -.06 ■ -T— l~ " ~ — . - "" ~" Seo/ ,.a I h-iL 1 -' ,- ■■^ ^ - - M -■ ' 1 r 1 ^ - s I-- . ^ --1 "^J " Y^ •7i.r \ ^ —1 -^ ■ - _ U ^ \ 1 __ (a) g--o (b) g^o.i o § I .Z4^ .16 J98 O -.08 a/ M/K/i-h , S "^ m S ^H ^=^; 5: iO g--o.2 . ^rnat u/icH-hta .32 — -- xr:-=.-= -X 1 ki- - '^a ~ ---'ife';:'^-^.^ :44-P~ = rrm Vcvr( Vr\\\ T >l '^J-fl r 0-+- r4-n T N '"■-'>, -^ r Til iriiT rk 1 Jj 1 1 1 U-ttn l^'l' 1 ,^ -' <7.<5 - ■/on IK ] - jITTT ■ p .(^(9 ■ \ - -\ 1 ■ \ o . 1 1 M 1 1 1 M 1 II M M M Mill III M M\l (djg--o.3 ■~ -— !!^ i M M I 1 1 , itv ff-O 1 1 M 1 1 M 1 -^O s \x^^ ^ ^JT S V ^Si S 1 o s i 7 -> ^ ^ \ -=" = ; --^^^ -^^ S ^ --'''' ---' ^ - ir - V S ^ - ^ ^ '' ^■^ 32-, "" -^ V ^p - -^ "^ - ^vfa>"^v -i 7)yt ^ s \ 7 \ .^4- S^ -r- \ X W. A \ s a^ W- ^ S : ■'^' X- ^ IT \ : t /OjC 3 "^ p n 'C ~[ ' J)QU. - - - ::3 (9 1 __ - _ II. -/£ -6-^0 ^ e /£ /6 <2o -/2 -e --? ^ -^ f 6 /z /6 ao Overhonq def/ect/on , 6h , deq ,^, fe)g--o.4. u ^ ^f^g__^^ Figure 11- rioment charactensTic^ of flexible ■sealj Mifh area far- ore bacKplafej. NATIONAL ADVISODY COMMITTEE FM AEMUUTICS NACA ARR No. L5F30 Fig. 12 U > I- a. 3 ac -J ? Z ui 2 " ii o u V \ C5 Q) •o ^ >Q \ \ \ \ ^ .■i^ N. ^ fi^ / ^ • Vy y? / Wm / yi'^^f y ' '' ^ "^A ^ -^ ' ^ ' *^~j^^ ^a ^ ~U^^ ' it /-;^/ -Ki' ^ ~~ ^<' Z^'' toj^- 7^ ^ 7* / ^5 z ^3 : *-l .L t I t'' \ t ^4 A I ::_ ./.eE^eeee^::::::::::::::::::: ro-; <5^ = 6 ' __ 1^1- ,^ ^^7/ ^'L^'^ ^ A^ i^-^ T--??^?- i#^^^^ ^'^ r^'-^ '•'^ 4^ z / ^= '^'^ t ^ ®<^^^ y ^ ^ '^ 5^0^ ?■ _ _ , ^ ^ si 'i? J- :> ^ -Z^tZ^ ^^ £ . _ 3 .4 b h .7 .(9 .9 -iO ---p — >- — X~"/ — •^ - -^'^Z -_7^ ZviS Zy^y I t^ 4j. y,i. /A 2A - -y^ // y^'^ 1-^ Gopa//dfh,g /^/ /± , _._ Tl^'ty ,?^^ ^-^ -11 ^ Um/^ r^'T/' -• ?^1^ / ^^ '- ' A^d-^l,t^ — ^ , * 7.^ l_ A 1. a V ' • ^^ J ^ 7 7% T- ^ jL y / J 1 -t / /^^ / ^ ,^-,^^3 7 / -,^y T 1 / 7 2 TSfa ^ 7 / Z ^^ Z Z V V Z V it 7 - 7. ^^ ^ A}^' •^ J. Z 1 ^LmZ i- Z ,'^^7' ; y^ 7 Z ^7 ,^ y ^ y^ Z 7 7 ^ ^ / Z 2 2 1 r F . /o rcy 6^ -14°. Figure 14.- Verfica/ clearance vertical -line bacKp/ofes -7 7r 77 ?-1 -. A Z^ 7 ,2/ Z 2- Z Z ? -^ ^ , ^Eii?'^^ 7 /- -'vK^' .7 7 ^ c2 T' ^ 7 ,^2^7 / z J r-7-i- / / ,^7 X^7 J- / /L /^/ 7 y 7 ,'^47 Z y 7 7 2Z y ^^/ Z ^SSt'^ v'^/i ^ ^3-7 y'^/ / / 1/ ^ r^ y ^ -, -y ^7' f- ^ 2 J Z i 0^'^ ^/ ^ 7 , ^,_?:_^^___/ ::::::::: ./ (b)6f^=IO\ .0 - 7 / y- p:/'7 '^ 32 ^7 Z 7^ Z 7 ^-^■y / 7 V 7 Z 7 -/^ 4 J. ^.3J. / / 1.7 7 z \/ JZ ^'^ z <;:! ,' /04-1. J ' / y / 7 ^'^ I 7 IE 7 4 ^7 z zt^ I ^ / JT^7 / 7 TO-f/ ^ z 7 " J. S- 7 ^ z ", i 7 y / z ^ J _r .-3 .^ .-^ .5" .6 .7 .S .9 1.0 Jeal luidth, s NATIONAL ADVISORY (dj 6l^ = <2 O °. COMMITTEE FM AEKONAUTICS required for flexible ^eah cuifh Fig. 15a-d NACA ARR No. L5F30 -J I 8 «^is^ ~ 3 6 y Jea/ width, s {C)6i^ = 14". /.o X - --I y _ ^nkz A27Z ^ -- vp/ - - VV^,'^ JL^ 7 7 yy 1 V St A ^ ^2 / t -AaM "^ J ^ '^ KlT ^ ' 7 , \>yi / . / ^ M^ / / //hs/ / f - ^;^ # Z 2 ^, ^^.^ V ^•'^^ ^'^^ ^ 7 /■ 7 V z ^'^,^ Z Zt J \^ Z ^T./ 7 / '^•Sil o^ ^'^ Z ^' 2 Z 2 __^L_2___z: ::::::::: /I 1 1 1 III -LU — LLLJJJ — 1 1 1 1 1 1 1 (b) 6^ -- IO° ■6l 1 1 1 1 1 1 1 ■ ' 1 ' 1 1 ' : _.:: .I'x ^ ^ 2 I / J " A , 7Tn,gyf 7 -a/ZZ V V \v/ 7 / 7t J J ^-K,y y ta^t ' J -asl 2 2 7 -N.X- V J. 7 Z X 7 A 7 / A- 2 y 4- ^ -, ,U / ^ * ^7 Ap.-tT , ^ 2 I "S -/ / V '^ 2- z - y ,^ Z 'as-l y 1 J. Z-4V Z J '^ ^ t" .3- .3 4 .3 .6 .7 .6 .9 W Seal ii//dth, 5 fdJ 6l = ^6l°. NATIONAL ADVISORY COMMITTEE FM «£>ONiUTICS Figure 15.- Vertical clearance rQqu/red for flexible sjeols cu/fh circular- arc bacKp/ote^. NACA ARR wo. L5F30 FiR, 16a, b ^ I ^ .Jc^ — 1 — ^ — /-/or-/'^o/7^c// - //r?G ^-tf . — ^ \ / \ / \ ^ 1 /6 / \ V / S ^ J- r^ -^ \ r-^ \ rxR y ^ X ^ \ — / ,^^ r ■^ s / J ^ -^ ' \ s / ^ C/r^cu/ar^ - arc /O ' . — ' J 1 ,. „ , 1 CcfJ p = O./ J .5 = 0.<^. .se /f^ .^o .32 .^^ Sc7c:AyO/:7/^ /£ -<3 —^ O -^ s \, 3 ^*N \ s \. S N L \, .6 \ \ \ o — \ /J ~~ ■^ ^ \ N, N, \ \ -2 \ \, \ s. N \ N V O \ \, \ \ v -vS N ^O .s \ -vf > \ •t \ -<5 \ L \ -^ \ 2a O 4- 3 /2^ /6 ZO Z/l r Fig. 19 NACA ARR No. L5F30 13 si Z LU O UJ c o u 0) o c o G o 13 0) rH td (U CO c •H ce o +J C o CJ 1 (U E I o J-i CID NACA ARR f^o. L5F30 Fig. 20 to Ho I 3 .2 O -.z -A -.6 -3 .20 1 jz — o — Unhah/ireef aj/era/^ ./6 ( k / (tesi u^pc/h/fsheJ ) ^ k / r Ba/a^cec^ a//eron .12 s \ \ / / r Ci/Co^O.S'S/^g - O jS = C>.< \ \ /, '/ f 5 .03 ^ V / / r £!a/a/7ced o//eror) \ ^ N / from opprox/ /na^e- .04^ xN !■/ A / for/?7c/i7) s ^$«l J K O % s K ^^ ^^^ ^ >^ -n4- \ ^^^~ % \ i -u \ s -n3 \ \^ \ ^s ^^ 5;^ -/z \ \ -X ^ H ) \ N (Y" < r^ -.16 -> Y \ \, ./ / \ \ -,2C / P \ \ / p \ ^ \ -.24 / \ A 1 r N ) h ^ f V / / y / t /" (• V rr y C )-< NATIONAL ADVISORY COMMITTEE FOt AEDONAUTICS -20 -/6 -12 -3-4- O 4 Q A//eror) or/g/e., ^_, d&^ /Z 16 20 Figure 20.- Hinge-moment characteristics of an aileron on an airfoil section having two balance configurations with the same effective overhang and vertical-line backplates. a = 0°. UNWERSlTY,OFFLOf''°*, yVS 08106 518 6 UNIVERSIW OF FLORIDA DOCUMENTS DEPARTMENT 120 MARSTON SCIENCE LIBRARY RO. BOX 117011 GAINESVILLE, FL 32611-70U USA