j\Ji\CPcL-^^>- NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WARTIME REPORT ORIGINALLY ISSUED May l9h-2 as Advance Eestricted Beport A FLIGHT INVESTIGATIOS OF INTEHJALLY BALANCED SEALED AILERCWS IH THE PRESMCE OF A BALANCED SPLIT FLAP By W. C. Williams Langley Memorial Aeronautical Laboratory Langley Field, Va. NACA "^ WASHINGTON NACA WARTIME 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 axe now unclassified. Some of these reports were not tech- nically edited. All have been reproduced without change in order to expedite general distribution. L - 2U2 {^5 YC m 6 jQ f^-a ffJ. cu NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS ADVANCED RESTRICTED REPORT A FLIGHT INVESTIGATION OF INTERNALLY BALANCED SEALED AILERONS IN THE PRESENCE OP A BALANCED SPLIT FLAP By W. C. Williams SUMMARY Flight tests were made with a modified Ryan ST airplane to determine the effect on aileron character- istics of various arrangements of balanced split flaps covering that portion of the wing span occupied by the ailerons. NACA recording instruments were used to determine aileron effectiveness. With the flaps fully extended, the aileron ef- fectiveness was reduced by approximately 18 percent of the effectiveness measured with ailerons alone. For the partly retracted positions of the flap, the corresponding reduction was of the order of 60 percent. INTRODUCTION Results are presented herein for part of an ex- tensive investigation conducted by the NACA to develop a satisfactory lateral control device for use with full- span flaps. In the full-span flap arrangement, with which this paper is concerned, balanced split flaps are located over that portion of the wing span covered by the ailerons, the inboard portion of the span pre- sumably being fitted with slotted or Fowler type flaps. The investigation consisted of flight tests in which the full-span-flap lateral control arrangement was simulated by locating a flap of the balanced split type under that portion of the wing span covered by the ailerons. The tests were confined to measure- ments of the effectiveness of the lateral controls. These flight tests were conducted by the NACA at Langley Field, Va. X SYMSOIS P V b rolling velocity, radians per second true airspeed, feet per second indicated airspeed, miles per hour wing span, feet wing ch ord flap deflection APPARATUS The Eyen ST airplane with internally sealed and balanced ailerons is described in reference 1. For the present investigation, balanced split flaps were mounted on fi.'ced brarkots over the outboard portion of the span, 'is shown in figures 1 and 2. Th3 fDaps covr'ied 38 percent of the wing span and had a chord of 20 tercent of ths wing chord. Th3 airplane was tested with several arrangements of flap deflection, fore-and-aft positions, and of the gap bei he flap aai the lower purface of the wing f 1 gu r e ? 3 to 6 , Thesfc ac-rang.-inent s are i J. lus t rsit e d in Standard KAC.-^ recording instrumen'c> wei'e used to measure a i r a p 3 ;.' d , c o u !; i- c 1 position, control f c r' c e , and rolling velocity. TESTS AND RESULTS The flight-test procedure to deteTniirs aileron ef- f f fict i "-.^iies .'.; w?=is the saiio es ^he w oi: ec.x:'^ desc r ihf>d ■ in re:':'»=:i"?r ce ]. . r:i--.-3 were r.nCe at approJii mat "ly .v? ar>d 85 L-.iij;'^ per h■-■^2.T, The n ct refep-ind ing v^ij.nas of air- plane I'-tt co^fiicient wtre appr O'-cirat eiy 1 . i and-0.56, respar-t .."■e3:y . The detailed resu]i.r, of 'the flight -Lejts ar*! p.-.-)jrnt3d in figar:;:^ 7 to 11 :; n vhich'tne aile-on eTft.- t.lronvos far^tor p^/SV 'is plctted as afvrcl;icu 0/ 1.h-i chs i.-^o j .-. ■ ' o:al ^.H-itot.. ?-.i.-_c. .. ...-., results is presouoed in the following table: Ji ? U'r.mai y of the Aileron e f f ect ive- limum |i) Aileron effective- ness (mas ness (percent of Flap arrangement effectiveness with Right roll Left roll a iler ons alone) Ailerons alcne 0.061 0.078 100 Flap deflection, .051 .063 82 40O; gap, 0.02cw; leading edge under aileron hinge line ■ Flap deflection, .05 .064 82 40^; gap, 0.04c,,.: leaaing' edge under hinge line Flap deflection. "''.022 ^,0295 37 14^; gap, O.OScw: leading edge 0.0325cw ahead of hinge line Flap deflection, ^ .0263 ^.0323 42 80; ggp, O.ClCw sealed ; leading edge 0.07c„ ahead of hinge line Average value The low aileron effectiveness obtained with the partly deflected flaps confirms unpublished wind-tumel data for a similar arrangement and additional wind- tunnel tests are now under v;ay in an attempt to determine a more favorable flap operating path. It is possible, however, that this low aileron effectiveness at partial flap deflections is not, in reality, a serious drawback, because a two-position flap arrangement may be used in which the flap passes quickly through the region of low aileron effectiveness. The balanced split flap is intended for use in the duplex arrangement wherein a Fowler or a slotted flap is used over the inboard portions of the wing; therefore, partial flap deflec- tions might very well be confined to movement of these inboard portions. Langley Memorial Aeronautical Laboratory, National Advisory Committee for Aeronautics, Langley Field, Va. REFSRSNCS 1. V/illiams, W. C, and Fleckner, H. F.: A Flight Investigation of Internally Balanced Sealed Ailerons. NACA A.R.H., Dec, 1941. MCA Tig. 1 a o u u Pi ■ o o a 3 S" p« •H g. O a> 01 I VI o o u NACA Fi'g.2 Figure 2. - Three-view drawing of the Ryan ST airplane with fixed balanced split flap. hACA Fi'ijg.OL* J?lgure j. Sketch of internally balanced aileron ana balijiced-split-riap arrangement as used on 4]ran ST airplane; fully extenaed position with 2-peroent gap. Wgure 14.. - Sketch of aileron and balanced-split-flap arrange.-nent as used on Hyan ST airplane; fully extendea position with tf-percent gap. NACA riga. 5,S Figure 5« ~ Sketch of aileron ana balanced-split-flap arrangement as used on Hyan ST airplane; partly retracted position with 2-percent gap. Figure 6. - Sketch of aileron and balanced split flap as used on Ryan ST airplane; partly retracted position Alth sealed gap. men rigs. 7,8 Figure 7«- Variation of helix angle pl)/2V with change In aileron deflection. Ryan ST airplane with internally balanced ailerons alone. Figure 8.- Variation of helix angle pb/2v with change in total aileron angle. Ryan ST airplane with internally balanced ailerons in the presence of the 0.20&„ balanced split flap. 6*. = 1;0°; gap =a02C||; leading edge of flap directly under aileron hinge line. MCA Figs. 9,10 .08 Vl (d o r.- ^/ ::P u > -^ c^ -^ Left /- ^ Rig it 5 2 Chang e In 1 total aileron ar 10 gle, deg 2 50 Zy- .nil ^ ^^ rr y ° r .08 Figure 9«- Variation of helix angle pb/2V with change in aileron deflection. Ryan ST airplane with Internally balanced ailerons in the presence of the 0.20c^ balanced split flap. 6^ = 1+0°; gap =0,0l4.Cw» leading edge of flap directly under aileron hinge line. .08 (mplD c 0) i.oJt _ 57 u > - Left ^ i^ — ^ Ri pht 5 2 Chang e in 1 total aller 3n an 1 gle. leg 2 50 C — ^_-— - "^ tOl; .08 Figure 10.- Variation of helix angle pb/2v with change in aileron deflection. Ryan ST airplane with internally balanced ailerons In the presence of the0.20c^ balanced split flap. 5f = lit.°; gap =0.02c^; leading edge of flap0.0$25cw ahead of aileron hinge line. MCA Pig. 11 CM -^ I 8 Change in total ,,-^ aileron angle, -D- .^'- -.-G4 .J.e£ .03 Figure 11. >- Variation of helix angle pi)/ 27 v;ith change in aileron deflection. Eyan ST airplane with internally iDalanced ailerons in the presence of the 0.20c,.. "balanced split flap. 5^ = 8' J gap = 0.01c,„ sealed; leading edge of flap 0.07c ahead of aileron hinge line. w UNIVERSrTY OF FLORIDA 3 1262 08106 482 5 UNIVERSITY OF FLORIDA DOCUMENTS DEPARTMENT 120 MARSTON SCIENCE LIBRARY P.O. BOX 117011 ■^AiNFCN/iLL E. FL 3261 1-701 1 USA