1、“ .#a .* - .-. . .-. .,-:A ,- J + , .#.;. . _- - -+-S:J!JS -: :.: - . / “llllll!lllllllll!llll!llil“- -i:-:”-z-:ii:rfi- := ,. .:. .=- ,., :.,; - _ L +z:. :y-L., :. ; i ,. .:=!- . _yd:- ., .- _-. - ,. -,:. -./# .-TECHNICAL NOTESNATIONAL ADVISORY COMMITTEE FOR AERONAUTICSNO. 763 .-WIND-TUNNEL INVESTIG
2、ATION OF TWO AIRFOILS WITH25-PERCENT-CHORD GNINN AND PLILIN FLAPSBy Milton B. Aries, Jr.Langley Memorial Aeronautical Laboratory, /WashingtonEay 1940 .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NAT IoNAL ADVISOR”y tiONMITTEE FCYR”AERONAUTICSTECH
3、NICAL NO,TE“NO. 763 ,WIND-TUNNEL INVESTIGATION OF TWO AIRl?OIGS WIT “25-PERCENT-CHORD GWSNN AND PLAIN FLAPSBy Milton 3. Ames, Jr”.,SUMMARY.,Aerodynamic force tests of an N.A.C.A. 23018 airfoilwith a Gwinn flap having a chord 25 percent of the over-all chord and of an N.A.C.A. 23015 airfoil with a Pl
4、afflap having a 25-percent chord were conducted in theN.A.C.A. 7- by 10-foot wind tunnel to determine the rela-tive merits of the Gwinn and the plain flaps.!Chetests indicated that, based on speed-range ra-tios, the plain flap was more effective than the Gwinnflap. At sqall flap deflections, tePlain
5、 flQP h the.lowe drag coefficients at lift-coeffici,ent ,values lessthan 0.70. For lift coefficients greater than 0.70,however, the Gwinn flap at all downward flap deflections hadthe lower drag coefficients,INTRODUCTIONImprovement in airplane performance has dependedsomewhat on the development and t
6、he use of high-lift de-vices. “As an aid to designers, the N.A.C.A. has conductedmany experimental investigations of various types of flapand has reported the effects of these different flaps Orihigh or low drag at high lift (gliao-ath control), low cdrag in the cruising-speed conditiohr and high li
7、ft andlow arag at the”take-off.The present investigation, conducted in the .NAoC*A.7- by 10-foot wind tunnel, was of a high-lift deviceidentified as the Gwinn flap and included for comparisontho te5.ts of a plain” flap. “The Gwinn flap is essentially,.a flat plate mounted at a point very near the tr
8、ailingedge “of the wing. In its neutral posit$on, the flap eX-tends past the traillng edge of the wing, there%y resultingProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 -N.A.C.A !?edhntcal .lJoto.lJo.763. . .,in an increased over -all .chord and wi
9、ng. area. In somerespects the Gwinn flap is similar to the plain flap.Both flaps deflect upward or downward so that either ofthem may ho Used “as a high-lift, device and the nodels used, however, were not comparable withthe Gwinn flap nodel used in this investigation. Thenodels of the airfoils with
10、the Gwinn wad the plain flopsused in these tests had the sane over-all chord., span,aspect ,ratio, and approxirmte naxtnum thickness.APPARA!l!US AIJD TESTSModelsTwo airfoil models were teited: An 8-inch-chordIJ.A.C.A. 23018 airfoil section with a Gwinn flap havinga chord 25 percent of the over-all c
11、hord (fig. 1) anda10-inch-chord N.A.C.A. 23015 airfoil section with a.plainflap having a 25”-percent chord (fig. 2). Each model hasa span of 60 inches and an over-all chord of 10 inches.The maximum thickness of the model with the Gwinn flap,based on over-all chord, is 14.4 percent of the chord and,o
12、f the model with the plain flap, 15 percent., Both air-foils and the plain flap are made of laminated beech; theGwinn flap is made of aluminum. In order to mount theGwiun fla-p; 5 percent of the over-all chord was removedfrom the trailing .adgo of the i?.A.C.A. 23018 airfoil sec-tion. The flaps are
13、arranged to move up or down alouttheir respective hinge axes Qr.to lock rigidly in a givenposition. Flap deflections were measured with respect tathe airfoil chord line, and all gaps between the airfoilsand the flaps were sealed with plasticize to prevent airleakage., .Wind Tunnel and BalanceThe tes
14、ts wero made in the N.A.C.A. 7-by 10-foot,tunnel, which has a closed throat and return passage. T.hetunnel and the ragular 6-component balance aro describedin references 2 and 3.F.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. . :. ”.,. . . N.A.C.
15、A. Technical Note No. 763 3Tests .,Test condit ions.- The dynamic pressure was maintainedconstant throughout the tests at 16.37 pounds per squarefoot, corresponding to an air speed of a%out 80 miles perhour at standard sea-level conditions: The average testReynolds Number was 609,000, based on the a
16、ir speed andthe 10-inch airfoil chord.l?est mocedure.- Tare tasts were conducted to d.eter-mine the e“ffects of the model-supporting strut on the lift,the drag, and the pitching moments of the two airfoils andflaps. .The main portion of the investigation consisted”indeterminations-of lift, drag and
17、pitchinflap deflections of -lOO;g mo:ents for=53, -20, 00, , , *o,150,300, 450, 600, and 790 throughout1- from -12 to beyond the stall for.in a;gle:of-attack rangeeach of the airfoils.Coefficients.The test” results are given in the form of standardabsolute coefficients of lift, drag, and pitching mo
18、ment., .,liftcL.qs .drag . .cD.qs, ,-. . . pitching monent about aerodynamic center of.Cm.(a.c*)o = , airfoil with flap aeut ral.qcs”. ,.,. . . . “. L lift .= ?* D drag”where.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 N.A.C;A. Technical Note N
19、o. 763S wing area.c over-all chord of dynamic prgssure.and a angle of attack.*.r-wing and flap.flf flap deflection (downward deflection is positive).All coefficients were obtained directly fron the bal-ance and refer to the wind (or tunnel) axes.Corroctd test results.- The data were corrected fortun
20、nel effoctrs to aspect ratio 6.iB free air. The s“tnndardjet-boundary corrections were applied. (See rt3ferenca 4.)In addition, corrections were applied for the effects ofthe supporting strut on the aerodyna_u3c. coefficients .of themodels as indicated by the tare tests.The corrected test results ar
21、e prosogted. in figures3 to 6 as plots of lift, dr,ag, and pitching-moment coeffi-cients and lift-drag ratio against angle of attack.DISCUSSIONGwinn Flap .,!The lift and the drag coefficients f%r the ai.rfoi.lwith the Gwinn flap are plotted against angle of attackfor the different flap deflections i
22、n figure 3. !Chopitching-moment coefficients and thG lift+rag ratios forthe came conditions arc plottwd in figuro 4. Figure 3indicates that CL varied regularly with flap deflectionexcept when the fla was deflected 30. TM irregularcurvo for the 30 flap deflection may be .a characteristicof the airfoi
23、l-and-flap combination, or it may to attrib-uted to scale effect. The maximum value of CL occurredat tif= 60 (fig. 3(b), and the maximum value of L/Dwas 18.6 at af = Oo (fig. A(a)* Tho variation ofm(a. c.)o with flap deflection was uniform; the upwarddeflections of the flap tended to give stalling m
24、oments,and the downward deflections gave diving nonents.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-r,1 1 1 1 , 1 b 1 tfl1 1 1 I 1 1 1 1.I-8+2-16-ZOI r 1 I 1 I I I , r I I , , , , , I , I I r r ! I I I II(a)-2$= _4 * ,2 ,6 . I !. i M+2 -8 -4 048.
25、12/620Angle of af)+xk,d , deg(a) Smallflapdeflections. (b) Largeflapdeflections.Figure4.- Pitching-momentcoeffioientaand lift-dragratiosof the rectang&r N.A.C.A. 23018airfoilwith 0.25cGwinnflap.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-%I.M.A.C
26、.A. TechnicalNote No. 763 Fig.5Angfe ofbfti, d &g . .-(a) Smallflapdeflections. (b)Large flap deflations.Figure5.- Lift and drag coefficiente of the rectangularH.A.C.A.23015airfoilwith0.24%plainflap.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-,N.
27、A.C.A.TechnicalNote No. 763 Fig.6(a) Smallflap deflections. “ (b)bge flap deflection.Figure6.- Pitohing-momentooeffioiente and lift-dregratiosof the rectangularN.A.C.A. 23015drfoilwith 0.25c-plainflap.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.
28、daFigure 8.-Effeot.offlapdeflectionon&iim liftcofif-fioiemt.III.0.25c.GwinnflapontheN.AC.A,230Baiandth60.250plainflapontheN.A.C. A. 2305a$rfoil.L I I I I I0+0010 I I I I I I I I I I I I Ilwm&flecym ,40&a 50 m 70,Figm-e 9.- Effeot of flap deflection on-dreg aoeffioientnat different 1ift coeff ioients. The 0.25c Gwinn flap on theti. A.C. A. 23018 airfoil. endthe 0,250 plain flap on theN. A.C. A. 23015airfoil.Draacoefftcient C.k,z0.+mm,1, 1 ,. . ,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
