I N GZ 50630 FILE COPY NO.· 2-W c I lE
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
REPORT No. 630
A FLIGHT COMPARISON OF CONVENTIONAL AILERONS ON A RECTANGULAR WING AND OF CONVENTIONAL AND FLOATING WING-TIP AILERONS ON A TAPERED WING
By H. A. SOULE and W. GRACEY
1938
For sale by the Superintendent of Documents, Washingwn, D. C...... - ...... - .. Price 10 cents Subscription price, $3 per year AERONAUTIC SYMBOLS
1. FUNDAMENTAL AND DERIVED UNITS
l\lC't)'ic English
Symbol Abbre\"ia (' lIit Abbrevia L' llit I tion tion
Length _ , meter 111 fnot (o r mile) __ _ ft. (or m i.) Time __ second_ __ _ S second (or hour) sec. (or hr.) Force weight of l kilogr~m kg weight of 1 pound __ lb.
Power P horHepower (metric) horsepo\\"er __ hp. miles per hOUL ______Speed __ _ \ kilometers per hour _ k.p.h. m.p.h. - {ltl eters per second m.p.s. feet per second _ _ f.p.s.
2. GE ERAL SYMBOLS w, ,Yeight=my v, Kinematic yi eosity g, Standard accekl'ation or grayity= 9. OG6;) p, Densit!, (mass per unit yolume) 4 llt ' S~ or ~2.17..jO [t. jsec. 2 ,Umdard delli-iity of dry air, 0.12497 kg-m- _s2 at W 1.io (). and 760 mm; or 0.002378 Ib.-ft.-4 sec.2 m, 11 ass =- 3 9 Specific weight of "standard" air, 1.2255 kg/m or I, :-loment of incl'tia= mF (Indicate aXIs of 0.07().,)11b. /cli. ft. rndius of gyration k hy proper ubscript.) CoefTicient of yiscosity 3. AERODYNAMIC SYMBOLS s, ~ \..I' ea _\..ngle of setting of wings (relative to thrust /)u;, Area of wing line) 0, Gap Angle of stabilizer setting (relatiye to thrust b, pall line) Chord Q, ResuJ tant mOlllent n, R esultant angular velocity ~ \. spect nltio n , . P -' Reynolds Number, where l is a linear dimension I, True nil' speed J.l. (e.g., for a model airfoil 3 ill. chord, 100 · 1 1'? '1, D ynuIllic pressure=2P - m.p.h. normal preSSUl'e at 15° C., the cor re ponding number is 234,000; or for a model of 10 cm chord, 40 m.p.s., the COl'l'csponding L, Lift, ahsolute coe.fficient C],= q.)~ f number is 274,000) D, Drag, absolute coefficient, OD = ~f Center-of-pressure coefficient (ratio of distance of c.p. from leading edge to chord length) Profile drag, absolute coefficient O})o=~S Angle of attack ~\..ngle of downwash Induced drag, ahsolute coefficient CDi=D t Angle of attack, inhnite aspect ratio q Angle of attack, induced Parasite drag, absolute coefficient ODP=~S Angle of attack, a bsoillte (measUl'ed from zero lilt position) c, Cross-wind force, absolute coeffiCient Oc= q~ Fli.ght-path a.ngle
R, Resultant force REPORT No. 630
A FLIGHT COMPARISON OF CONVENTIONAL AILERONS ON A RECTANGULAR WING AND OF CONVENTIONAL AND FLOATING WING-TIP AILERONS ON A TAPERED WING
By H. A. SOULE and W. GRACEY Langley Memorial Aeronautical Laboratory
74706-39 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
HEA DQUARTERS. NAVY BUILDING, WAS Hl GTO , D, C, LABORATORIES, LANGLEY FIELD, VA.
Created by act of Congress approved March 3, 1915, for the supervision and direction of the scientific study of the problems of flight (U. S . Code, Title 50, Sec. 151) , Its membership was increased to 15 by act approved March 2, 1929. The members are appointed by the P resident, and serve as such without compensation,
Jo EPH S. AMES, Ph. D., Chairman, SYD EY M. KRAUS, Captain, United States Navy, Baltimore, Md. Bureau of Aeronautics, Navy Department. DAVID W , TAYLOR, D . Eng., Vice Chairman, CHARLES A. LINDBERGH, LL. D ., Washington, D. New York City. WILLIS RAY GREGG, Sc. D ., Chairman, Executive Committee, DENIS MULLIGA ,J. S. D., Chief, United States Weather Bureau. Director of Air Commerce, Department of Commerce. WILLIAM P. MACCRACKEN, J. D., V ice Chairman, Executive AUGUSTI E W. ROBINS, Brigadie:- General, United tates Committee, Army, Washington, D. C. Chief Materiel Division, Air Corps, Wright Field, CHARLES G. ABBOT, Sc. D ., Dayton, Ohio. Secretary, Smithsonian Institution. EDWARD P. WARNER, Sc. D., LYMA J. BRIGGS, Ph. D., Greenwich, Conn. Director, ational Bureau of Standards. OSCAR WESTOVER, Major General, United States Army, ARTHUR B . COOK, Rear Admiral, United States Navy, Chief of Air Corps, War Department. Chief, Bureau of Aeronautics, Navy D epartment. OLt\'ILLE 'WmGHT, Sc. D., HARRY F. GUGGENHEIM, M. A., Dayton, Ohio. Port Washington, Long Island, N. Y.
GEORGE IV. LEWIS, Di1'ecto'l" of Ae1'onautical Research Jon ' F. VICTORY, Sem'eta1'y HENRY J. E. REID, Enginee1'-in-Cha1'ge, Langley Memorial Aeronautical La/)o1'at01'!J, Langley Field, Va,
JOHN J. IDE, Technical Assistant in EU1'ope, Paris, France
TECHNICAL COMMITTEES AERODYNAMICS AIRCRA FT STR UCTURES POWER PLANTS FOR AIRCRAFT AIRCRAFT ACCID ENTS AIRCRAFT MATERIALS INVENTIO S AND DESIGNS
Co01'dination of R esccL1'ch Need.< of Militn1'!J nnd Civil 11 viation P1'epa1'ation of R sea1'C!z P1'ograms Allocotion of P1'o blems Prevention of Duplication Conside1'ation of Inventions
LANGLEY MEMORIAL AERO AUTICAL LABORATORY OFFICE OF AERO AUTlCAL INTE LLIGE CE LANGLEY FIELD. VA. WASHINGTON, D, C.
Unified conduct, for all agencies, of Collection, classification, compilation, scientific research on the fundamental and dissemination of scientific and tech problems of flight. nical information on aeronautics, REPORT No. 630
A FLIGHT COMPARISON OF CONVENTIONAL AILERONS ON A RECTANGULAR WING AND OF CONVENTIONAL AND FLOATING WING-TIP AILERONS ON A TAPERED WING
By IT . A. 0 Lf; and W. GRACEY
SUMMARY AIRPLA ES A D WI GS Flight tests comparing the relative effectiveness oj con The Fairchild 22 airplanes used in the investigation ventional ailenns of the ame size on wings of rectangular are shown in figures 1 and 2. The rectangular wing, and tap red plan Jorms were made with a Fairchild 22 which had the arne plan form as the standard wing airplane. Injormation is included comparing conven (or the F airchild 22 fti.rplanes, had a span of 32 feet 10 tional and floating wing-tip aile."ons on a tapered wing. inclle , a chord of 5 feet 6 inches, an area of 171 square The 1'esults showed that the conventional ailerons were [' et, and an N. A. . A. 2Rl12 airfoil section. The somewhat more effective on the tap3red than on the rectan conventional aileron with which this wing wa fitted gular wing. The difference, however, was so mall as to be had a span of 13 feet 3 ~{6 inches ( 1 percent b/2) and impercepti ble to the pilots. The floating wing-tip ailer ft chord of 12 inches (1 percent c). They were ons were only half a effective as the conventional ailerons and, jor this rea on, were con idered unsatisfactory.
I TRODUCTIO At the reque t of the Materiel Division of the Army Air orp , the J. A. . A. has conducted a eries of iliO'ht te t to compare the relative effectiveness of con ventional aileron of a given size on wings having rec tangular and tapered plan form. Earlier wind-tunnel tests are reported in references 1, 2, and 3. The FIGURE I.- F airchild 22 airplane used for tests of conventional ailerons on a flight te ts were made with two :B aiTChild 22 airplanes. rectangular wing. The two wings used in the investigation were of the arne area and span. One had a rectangular plan form with semicircular tip and the other a taper ratio of 2:1. The conventional ailerons with which these wings were fitted had the same plan-form dimen ion and were arranged during the flight te t to have approxlmfttely the same deflections. The te ts consisted of the determination of the effec tivenes of the ftilerons (1 ) for different degrees of deflec FIG URE 2.-Fairchild 22 airplane used for tests of conventional ailerons on a tion at two air speeds, and (2) £01' full deflection at tapered wiug. various air speed throughout the peed range of the airplane. The comparison are based on the maximum operated differentially, having a maximum upward mea ured rolling acceleration and velocitie , the ob- deflection of 17 ° and a downward deflection of go. erved yawing action, and the computed rolling-moment The tapered wing (figs. 2 to 5) ha.d the sa.me span and coeffi cient. ftrea. as the rectangular winO'. It had a 2:1 taper ratio In addition to being fitted with the conventional with a straight trailing edge. The trailing edge wa aileron, the tapered wing wa equipped with detach made straight so thali lihe aerodynamic centers of the able wing tips that could be replaced by floating win o- tapered and rectangular "'rings could be located at the tip aileron. The Do ating wing-tip ail erons were also same point relative to the fu elage while still permit te ted during the ill ve tigation and were compared ting acces to the rear cockpit. In external dimen with th conventional ailerons on th e ame winO'. sions the tapered wing wa comparable with an 111- 1 2 REPORT NO. 63D-NATIO AL ADVI ORY COMMITTEE FOR Al£RO AUTICS tern ally braced wing alt.hough it was supported ex ailerons on the rectangular wing. They w 1'C operated ternally for the tests. The airfoil section varied from differentially and, for the tests, were limited so that an . A. C. A. 2218 section at the root to an . A. C. A. the maximwn upward deflection was 18° and the 2209 section at 15 fcct from the axis of symmetry. The downward deflection 9°. Owing to differences in the aileron-operating mechanism, the maximwn aileron deflections on the tapered wing were obtained with a stick deflection of 14°; whereas, with the rectangular wing, the maximum deflections were obtained with a Con ventional stick deflection of 20°. The plan view in figure 3, on a ileron: Floatln9 - tip which the rectangular wing has been drawn in outline, aileron "~''F::::::::::::-=-=-=-=~-=~~tt:+=~;:::=~~~ gives a direct comparison of the wings and the conven ,.-1.1 tional-aileron installation. : \ : '- - -- Detachable win g t ip
'to dihedral L ~35__' _IO"" __ 1., 8 ' 0 ' ------"-1 - 7' 7"- Front face of rear propeller 2 ' III:V " - 21 ' 6 " - --. --17" ,/16 2 ' 6Ji6': ~-k~t---.-~,- flange , ,. I \"~ " ::----'1'-." 5 0 I , "T. 5 ' IlfJ" Thrust axis ·. I 9' 0 " (a) Install ation of fi xed wing tip. 1 ~- ,- , 4 ' /OXs " FIGURE 3.- Three-view drawing showing the installation of the tapered wing on a Fairchild 22 airplane.
(h) Installation of fl oating wing-tip aileron. F IGURE 5.-View of right wing,
For the installation of the floating wing-tip ailerons, the £L;;:ed tips of the tapered wing outboard of the 15-foot station were removed and the conventional ailerons 30° were locked in their neutral position. The floating wing-tip ailerons had a symmetrical . A. . A. 0009 airfoil section at the root. Each aileron had an area of 7.9 square feet and a span of 35 inches; the wing area / and the span with the e ailerons were 177 square feet FIGURE 4.-Section through tapered wing at outboard end of conventional aileron. and 35 feet 10 inches, respectively. These aileron wing tips were rounded. The chord varied from 7 feet were statically balanced about a hinge axis 17 percent 4 inches at the root to 3 feet inches at the 15-foot back of their leading edges and were permitted to float station. freely between limiting positions of 40° up and 30 ° The conventional ailerons on this wing had the same down. The ailerons could be deflected relative to span and chord and were located in the same position one another to obtain a maximum angular difference relative to the wing span as were the conventional of 30° with a stick movement of 24°. COMPARISON OF AILERO o A RECTA JGULAR AND A TAPERED WING 3
I J II I I I I Air spe ed, fp.s . Air speed , fp s 0-----9 0 - 0----84 - 138 138 V '" V I---- '" 1-- ./V /' ~-; I---- " /' I 0 l- V ~v ./ .~ ."- I ...... - ..Jl'''- --- .-if o..-~ V V ~ -- ...... "- V'" V ---- _0"- ° ./ .? I !--O- 5 5 " I ~ ~-- AIrspeed, fp.$. ~ -- ° - " 0---83 " .. 131 . ~/ ~- --f-- f--f- ° ~ --V-::.9 -- - r-- f--I- - __ - ~/..-Y -- ''- 1-- ~~-..- I- 1--1-- ::;.-- 0 _ 0 - p6"~b:Cf I I- 1 - I-- - . ..--E I--~ _ 0---- J..onvenlional atlerons on tapered wm. g . '-- !.-a-- --I--- .,- 6- - -- - " "II rec/ongular wIng IS>-- ~---- -<:J Standard Fairchild CC oilerons ond 1- ~~o- 1-- r-- r--_. w ing(from reference 4) i- ~~~_ f-- -c 0- o o I .8 - 8 . . 8 -.. f--~-_ _ - 4 ~ .. --i ~- .. )g-~ ~ ~ -~ - .- - 1--- ..0--hf" ~- -- ~ F--' f--'::::: - r---- - ~ ~ --.0 -- .... --- .---;:- 1------~ .-- - - r ~ .- -- v--:~ 1.-0.,..,% -- V~ pO - r-' I .I - ----I ~1~ ~ Ar l o 80 90 100 //0 120 130 140 ISO o cO 40 60 80 Air speed, fp.s A iler 0n df'flection, p ercent FIGURE S.-Comparison o( the maximum rolling velocities and accelerations with (ull FIGURE g.-Variation of the maximum rolling velocities and acceleration;; defl ection of conventional ailerons on the rectangular Bnd the tapered wings. with de fl ection of floating wing· tip ailerons on the tapered wing. ------ 4 REPORT NO. 63G-NATIONAL ADVI ORY COMMITTEE FOR AERONAUTIC TESTS AND RE ULTS The results of Lhe m a urements arc pre ented in figure 6 to 12. Figures 6 and 7 show the results of With each of the lateral-con trol sy tern ,two cries of the partial-deflection Le ts of the conventional ailerons Lests were made. In Olle cries, the ailerons were on the rectangular and tapered wings. The ailerOl1 - abruptly moved to their maximum den ections c1lll'ing defl ection scalcs of thesc ligu l"C arc ba cd on Lhe dificl' sLeady fligllt at ya,.ioll peeds throughout the flight encE'S between the angles of the up and dow n aile rons. runge. In tIle oLber cries, the amount the nilerons For the thrce aileron sy teInS tested in the illYe, tig:l were moved wa yaried at each of two air peed" one in tion, the aileron deflecti.ons wcre approxima tcly pl'O Lhe high-speed and tll e other in the low- peed range. pOl·tional to Lhe deflecti.on of the control stick. Figure ]~ach serie of tests wa s made in gliding flighL for only compare the rolling efl'ectivenes for full defl ection right deflections of the tick. Records were made of /.0 ~ 5 .06 ~ )Iootn)-t) o i/~r o ), s _ -- --Conventionol " j- --r . - i-- .8 ___ 1-f- .05 G - .-f-- f,o-- l--...... V,,:;--- .6 :- . 1---1------r vroc~ f.-- J...- P--- I <:;:'celeralion - 1-=.-- j..-"- .....1 ------,Velocity1 .4- ~t ----" V- - t--- t-- - r--- I ' r- =-0 , , - - V;..--- . - ~~~ I- .-;.0-- I ,0 j..J>-- r--o I I 01 0 !---- ..0---!---- .2 0 r-- -, V 0 '-A cceleraiion -"'" V I f-""" l- i--- 0 - - -- - Conventional oilerons on rectangular wing 90 100 11 0 120 1.30 14 0 o Air speed, f".p.s. .01 -- II "" tapered 1/_ --Flooting-lip " " " " FIGURE IO.-Comparison olLho maximum rollingvolocitiesand accelerations with full t------Standard Fairchild 22 ailerons and I c1~ n ection of the co nventional and fl oating wing·tip ailerons 00 the tapered winl(. 4 re~ere;ce 1 } 1 2 0 1 I w1tgtOj I I , o .2 .4 .6 .8 1.0 1.2 - I- Lift coef/'ieienf, CL ~ i'-- r---.. F"'!:HE 12. Comparison of tbe rolling-moment cO('mcients of the l al~ra l -cont rol 6 systems tested. a ' r-..::.. r-- t--...R r-- t---. I of the ailerons on the two wings. Also shown in this 2 ~ 0 figm'e are the result of tests of the standard wing for I or- ~ the Fairchild 22 airplane. These results were used as a 8 I ba i for comparison of the different types of lateral I 1-- .-- I c?ntro~ treated in reference 4. Data si~lilar to. those glVen m figures 6 alld for the cOllventlODal aileron 4 I- -- are given in figures 9 and 10 for the :[loating wing-tip ailel'on. The mean flofttin g angles of the wing-tip ailerons at various speeds in steady flight are hown in 0 90 100 110 120 130 140 figure 11 . Air speed, fp.s. FIGI'ItE 11. Variation of the mean fl oating angle of the wing-I ip ailerons with speed. Figme 12 ha b en prepared to compare the lateral control sy tems on the basis of the rolling-moment the initial air speed, Lbe amount the ailerons were coefficients. The method of computation used in the moved, and the angular velocities of the airplane in preparation of this figure involves a correction of the rolling and yawing. These mea urements were up measLll'ed acceleration to zero rftte of roll so that the plemented by pilots' ob ervations of the control action computed coefficient arc comparable with tho e ob and control force. tained from wind-tunnel test. (See reference 4 for The records were inspected for any lag or luggi hue details of method.) The moments of inertia of the in the response of the airplane to the aileron movem nt airplane about the X body axe were required for the and for the direction of the initial yawing velocity. computations. The moment of inertia of the airplane From the records of the rolling velocity, the maximum with tbe rectangular winO" was 707 slug-feet 2; that for rate of roll resulting from a given aileron movemen twas the airplane with the tapered wing was 766 slug-feet 2 directly obtained. The maximum angular acceleration as flown for tests of the conventional aileron and 1,018 in roll were obtained by differentiation of the rolling slug-feet 2 as flown for the tests of the floating wing-tip velocity records. ailerons. COMPARISON OF AILEROI Or A RECTA GULAR AND A TAPERED WI G 5 DISCUS 10 made of the control effectiveness at and beyond the stall COMPARISON O},' CONVENTIONAI. AILERON 0 RECTANC LAR howed that, although the aU'plane could not be con AND TAPERED WINGS trollecllaterally at the stall with either of the ailerons, The rolling effectivene s of the conventional aileron some control ffectivenc s wa retained beyond the stall on Lhe rectangular and tho tapered wings may be com with the floating wing-tip ailerons but not with the pared on the ba is of the ulformation given in figures conventional ailerons. and 12. FiO'ure sh ows that the maxunum rolling accel Aside from the low rolling effectivene s of the wing erations given by the ailerons on the two wing were ap tip ailerons, their behavior wa normal. The re ults of proximately the same. The maximum rolling velocities thc partial-deflection te t given in figure 9 show that attained were lightly O'reater with the tapered th an the variation of control effectivene with aileron deflec with the rectangular winO'. The difference in the roll tion is nearly lineal'. 0 lag or luggishne was ing velocities was of a magnitude sufficient to maIm a recorded or observed by tbe pilot . A smail positive difference of 2° to 3° out of approxiInately 25° in the yawing action was noted. The pilots estimated that angle of bank attained in 1 se ond after the control the stick forces with t he win O'-tip aileron were ahou t movement. This difference wa not discel'llibl to the one-quarter of tho e for tIl e conventional aileron on pilots making the te t , who reported that the l'ollrng tbe rectangular wing. cO'ectivene s was equally good with either wing. It i appreciated tbat tbe area of the wing-tip ailerons The rolling-moment coefficients given in figure 12 could be con iderably increased in size with an accom al 0 howed that the comrcntional ailerons, when in- panying increase in eiIectivene s before the stick forces taIled on the tapered wing, are omewh at superior to approach those of conycn tional ailerons. (ee refer LIt e same ailerons ,,-hen in t, Ued on the rectangulu.r ence 5.) Tlti in crea e in ailcron area could not be wing. The impro\'cment varied slightly "'itll lifL accompli hed, llOweveJ' , wiLh out unduly inC'reasing Lbo eoefficient and W u. s, GOVERNMEN T PRINTING OFF I CE: 193 9 8 " "- '- z Positive directions of axes and angles (forces and moments) arc shown by arrows I Axi" I I :r.lom('nt abo1lt axis Angl(' Velocities --- I Force 1 (parallel Linear fhll1- PO 'iti\'(, Designa- YJll- (com po- Designation Sym- to axis) D('signaLion Angular bol s~' mbol hoi direction tion hoi llentalong axis) I 1- - - - -I I -' - - } . Loo,it,d'n. L __ . _I X I X Rolling_ __ _I L -'lZ RolL __ '1 l- ll' r -- I --- Absolute coefficient of moment Angle of set of control sW"fuce (relative to neutral L O=M X position), O. (Indicate surface by proper subscript.) O'=qbS m qcS O"=qbS (rolling) (pitching) (yawing) 4. PROPELLER SYMBOLS D, Diameter P, Power, absolute coefficient CP = ~nr. P, Geometric pitch pnJ.F plD, Pitch ratio as, Specd-powE'l' COC[fiCient=-V ~~~: V', Inllow yelocity V., Slipstream yelocity Efficiellcy T 11, RCTolutions pCI' , ('cond, l·.p. T, Thrust, absolute coefficient OT= 2D4 pn Eff~cti\'e helix angle= tan-Ie .... 17 ) ~7Trn Torque, absolute coefficient CQ= Q, p1/.~D5 5. NUMERICAL RELATIONS 1 hp.=76.04 kg-m/s=550 ft-Ib./sec. 1 lb. =0.4536 kg. 1 metric horsepower= 1.0132 hp. 1 kg=2.2046 lb. 1 m.p.b.=0.4470 m.p.s. 1 mi.=1,609.35 111.=5,2 0 ft. 1 m.p.s.=2.2369 m.p.h. 1 m=3.2808 ft.