NASA NACA-ARR-L5C01-1945 Wind-tunnel investigation of control-surface characteristics XXI medium and large aerodynamic balances of two nose shapes and a plain overhang used with aoil.pdf

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1、 d.- , - , . Ft-2 IIII!M3JL i !1jllllMM688-Y,whereas a 13- to 17-percent reduction occurred as aresult of unsealing the gap at the flap nose on theflap with aerodynamic balance. The change in lift withflap deflection .was found to increase as a result ofsealing the gap at the flap noseand.of changin

2、g thenose shape from elliptical to blunt.RESTRICT13DProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. 7 :.P2 NACA AKR No. L5C01 . The effect of unsealing the gap (except for the plain .0flap), increasing tke balance length, and changing thenose shape

3、 from elliptical to blunt was to make the rateof change of flap hinge moment with flap deflection (atsmall flap deflections) and with angle of attack morepositive. Some overbalance was foundon the 50-percent-flap-chord overhangs.When the lift was varied by changing the angle ofattack at zero flap de

4、flection, the center of lift wasat the 24-percent-chord station for all overhangs testedwith gap sealed The center of lift due to angle ofattack and that due to flap deflection generally movedrearward as the gap wa unsealed.INTRODUCTIONThe NACA is conducting an extensive investigation to .provide ex

5、perimental data for design purposes and todetermine the section characteristics of various types- of flap arrangement suitable for use as control surfaces. The investi-gatian is being made in tineLangley 4- byS-foot vertical tunnel and has included tests in whichflap profile, trailing-edge angle, ga

6、p size, flap noseshape, and balance-chord length-havebeen varied. otof these tests have been made, however, of a 30-percent-chord flap. In the present report, the investigation isextended to determine the effects of flap nose shape and.balance-chord lenh on an airfoil having a 40-percent-chord flap.

7、 Data on the pressure across the seal of theplain-flap nose and a metlnodof applying these pressuredata in the design of internal balances are presented.Tab data,are presented for aflap with a plain overhangand with aerodynamic oalance.SYM13C!LSThe coefficients and the s-ymbolsused are definedas fol

8、lows: “() .C$ airfoil section lift coefficient 2()doc% airfoil section profile-drag coefficient ACdo increment of section profile-drag coefficient dueto flap deflection.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. .NA6A ARR ?0.LCOl 3()mcm airfoi

9、l section pitching-moment coefficient hf qc2ch()flap section hinge-moment coefficient fqcfzhtcht()tab section hinge-moment coefficient qct2Pq resultant nressure coefficient (L i u)where.1-hfIIhtIcc-fCtc1PLPucbao/ - .- .,airfoil section liftsirfoil ssction profile dragairfoil section pitching moment

10、about quarter-chord point of airfoil (positive moment movesnose of airfoil up)flap section binge moment about flap hinge axis(positive moment moves trailing edge down)tab section hinge inomsntabout tab hinge axis(positive moment moves trailing edge down)chotidof basic airfoil with flap and tab neutr

11、alflap chord from fla hinge axis to trailing edgetab chord fomtab hinge axis to trailing edgefree-stream dnamic pressurestatic nressure on lower surface of sealstatic nressure on uper surface cf sealbalance chord“for atrfoil of infinite aspectangle of attacaratio (positive when nose of airfoil moves

12、 up)flap deflectic-with respect to airfoil (positivewhen trailing edge is deflected downward)tab deflection with respect to flap (positivewhen trailing edge is deflected downward)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4alsoNACA AR3 ?O. L5C01

13、ched to the balance frame by torque tubes thatextended through the sides of the tunnel. The angle of.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-“.lTACAARR NCI.L5C01 5a71attack was set fom outside the tunnel by rotating the .torque ttiqs with an

14、electric drive. Flap,deflections were set.by .mqans of an electrical position indicatoiand tab deflections were,set with a tempet: The hingemomentsof the flapweremeasured with a spec,ialtor,que-rod balance built into the model. For thetab tdsts, .tab hinge moments m;eretaken.by “- electrical ptraing

15、age installed in the model. For the plain sealed flap,the pressure difference across the -sealQf the gap att+heflap riosewas measured cm amnom,6ter. - - . . .The 2-foot-chord b? L-foot-span model (fig. 1) wasconptructe,of laminated rnahogahy (except for a steel. .tab), “wasaeodynamically smooth, and

16、”wasmadeto con-form to.the,:gCA0009 profile” (table 1).”-It was -.equippedwith a,0.4.0c.flanand a 0.20cf ?afn tab. .,. .,.”. .The flaq had a nlain-nose”overharig”with-a radiug .ofapproximately ,one-alf of.the airfoil thiclmess at theflap hinge.axis and.was so constructed P.atit could be.fitted with

17、aerodynamic.balances”thatwere 75 and 50 per-cbnt o,ftheflap chord,. These balancps”were of bluntand e.llipti,calnose shape. he ellipticalno-sewas atrue ellipse faired.tangent to the a-itifoilconto,w atthe flap hinge axis. The ordinatesfed th6:elliptical-nose overhang are given in table II. The nose

18、radiishown in figure 1 determined the blunt and plain noseshapes. The various overhangs consisted of nose blocksthat could be attached interchangeably to the flap atthe hinge axis. lh order to keep the 0.005cgap at theflap nose (flap gap) constant, these nose blocks werematched by interchangeable bl

19、ocksin Ehe airfoil justforward of the flap. An airtiaht”fabric coniiectedtheflap nose ar+d.the forward part of.the.airfoil for thesealed-gap tests, . .,., , .The 0.20cf :tab was made of steel and “thenoseradius was approximately one-half of the airfoil thiclmessat the tab hinge axis. The gap at the

20、tab nose (tab gap)was 0.0010.TESTS.Tm order that the te”stresu-ltsma.ybe-found easily, “tha various flan configurations te:tedand: the ,fiogure numbers of the corresponding plotted data are given intable 111.I _ . . . . . . . - - - ,: .,., -p,. .,.,.: ., .+ .- ,- “-.,. :. . . , - - .- ,- . : “?:.:.-

21、:,:“.- xJ.,”.2”+.:.:.,.,.-.:.,:,. ;- -, -. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6,NACA ARR 0L5C01 .The testswere made at a dynamic pressure of15 pounds per square foot, whi-chcorresponds to a velocityof about 71 miles er hour at standard

22、sea-level condi-tions. tie test Reynolds number was about 1 330,000 Sfice the tunnel turbulence factor is 1.93, the effectiveReynolds nwber was approximately 2,570,000. The Machnumber for these tests was about 0.09.,The znaxfmtievror in angle of attack appears tobe iG.OIt is estimated that the flap

23、and tab deflec-tions ivereset to within *0.2.An experimentally determined tunnel correction wasanplied to tke lift. .Theangla of “attackand .hing.emoments were corrected for the effect of streamlinecurvature induced by the tunnel walls, The method use,dto determine these corrections is similar to th

24、etheoretically derived analysis cmesented in reference 3for finite-span models. The increments of drag are .thovghtto be reasonably independent oftwnnel effect;although the “absolutevaluesare subject to an undeterminedcorrection. Ihaccuracw in the model construction andin the assemblv of the interch

25、angeable blocks probablycaused the small amount of flap hinge moment at zeroangle of attack and flap defl.ecttoq;, DISCUSSION , “. .Lift “ ,-Ihelift-coefficient curves for the flap with a.plain averhang and with aerodynamic balance,are-shown infigures 2 to 11. With the Sap either sealedor.unsealed,t

26、he iii%-coefficient curves wers nonlinear at largeflap deflections!l!ke-slopeof the lift-coefficient curve Cta(table IV) was approximately the ssme with gap seald-for all flap arrangements regardless of aerodynamic-balance shape or length except for the 0.50cf elli,ptical-nose overhang for which the

27、 slope was about 3 percentlarger.thsn the average. Unsealing the gap caused a)+.-percentreduction in sloge for the _flapwith a plainoverhang and a 13- to 17-Perceat reduction for the flapwith blunt end elliptical overhangs. For a given balance.“.Provided by IHSNot for ResaleNo reproduction or networ

28、king permitted without license from IHS-,-,-NACA ARR IOoL5C01 7. .chord and with gap sealed, aC7 was aproximatel thesame regardless of nose sP.aps.The change in lift with -flapdeflection C%fincreased when the flap gap was sealed -d when.the noseshape was chanGed.from elliptical to bl-m. .Theflaplift

29、 effectiveness a varied in .asimilar marinerexcept that,in the casa of”the O.Ocf blunt-nose over-hmg, af decreased when the gap was seaied. It shouldbe remembered that the uaramters shown in table I“,rwere measured over a small flap-deflection range (0 to 5)and therefore are used mainlT to compare t

30、he variousflap configurations tested.tie curves of flap hinge-mommt coefficient as afunction of angle of attack at a constant flap deflectionfor the flap with plain and balazncedoverlvangsare alsopresented in figures 2 to,11.For the 0.50cf blunt overl.angwith gap both sealedand unsealed-and the 0.50

31、cf elliptical overhan withga unssaled, tbe aerodamic characteristics at largsflap deflections were not determined because of violentoscillations that might have damaged the tumel apparatus.Ranges in which oscillations occurred are noted by dashedlines in the hinge-moment curves; Similar oscillations

32、encountered on another flap fittad with an aerodynamicbalance are discussed in referents .The hiige-monent parameters presented in table IVindicate that an overbalance condition occurred for the0.50cf blunt-ncse overhang with gap either sealed orunsealed. The 0.50cf elliptical overhang had a positiv

33、eChfa for both gap conditions end had small negativevalues of ChfG for small flap deflections to about 5(figs. 10 and ii).When section data are applied to finite spans, theaspect-ratio corrections for streamline curvature arealways positive (reference 5). Since the hinge-moment . _ -. . . - .-r. : .

34、 -., ,. . : ., ,. .-.- = , . . -. /. . . ., .,:,:, ”. , J.,. ,.:-,:.- ”1:.“ _. . ,.,., .-,- :, . : . . .J. ,. - ,. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 NACA ARR YO. L5C01Daraweters For seveal arrangement: 03 the flap with.balsxcedoverha

35、ngs are very small and the signs critical,the slopes may nass tlmogh zero and an overoalanced=flapnay result.The effect of ses.lingthe flap gap was to make Chfaarid chf6f .more negative except that, with”the flaphaving a plain overhang, the opposite effect occurred.Increasing the bala?celength made

36、both Chf and Chfa 6fmore positive. For a given balance chord, graater balancewas obtained at smal flap deflections with the blunt nosethan with the elliptical -nos.e.,Examlriationof the curvesshows, however, that, at Iargs flap Deflections for the0.35cf overhan, the elliptical-nose overhang had theg

37、reater hala_nctnga+fect. The variation of the hinge-moment parameters with overhang for the elliptical andblunt nose is shcwn in figure 12.Because the hinge-oent paramers shown in table IVand fi:gure12 represent the slopes of the curve at zeroflap da?lection and e of attack, these pareter-shouldbe u

38、sed mainly as an indication-ofthe relativemerits ofthedifferent flap nose shanes. 3ecause th3 tabulated slopesare valid for only small ranges, tileslones from thehine-moment-coefficient curves rather than the valuesof table IV should be used in calculatingthe charac-teristics of s control surface.s

39、present investigation did not include.tests.todeteriilethe effect on fla hinge moment.ofosealtigthe tab gap. It LS thought that hhe flap hinge momentsfor a flap without a tab (or with tab gap sealed) mightvary somewhat from the flap hinge moments of the modelconfiauzations tested with tab gap unseal

40、ed.PitchinS UomentThe values of the -pitching-moment parame-ters-rmcz)+d (%)ao,t in table IV determine the position ofthe center of lift with respect to the rparta-chordpointof the airfoil. When lift was varied by changing theangle of attack with a -iapdeflection ofOO.,-the-centefi.-.Provided by IHS

41、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-.l!ACAARR ?iO.L5C01 9of lift was at amoximately the 0.2!l+cstation for allorer!hangstested itigap sealed. Thsealing the gaphad go effect on bhe centeu 01 lift Or the nlain flapbut moved tke center of li.itrearuard to

42、the 0.25c sta-tj.onfor the 0.55c overhang and rearward.to the Q.26c sta-toionYortk.e0.50c o-.rerha.ng.Ikefollowing table gives the position of the centerof lit caused b flap deflection:lap gapSealedo.do5cPosition of center of lift causedby flap deflectionI I0,j5cf overhang 0.50cf overhangPlainoverha

43、ng Blunt 211iptical Blunt Elliptical:ioseI nose “nose noseO.j ci0.38c.3 c .39C : l:;%/ O:,.onofEhe aspect ratio (references and 6) a.flmoves towad.tlzetra,lt.ngedge as the aspectratio decreases.measured values of drag camot oecosideredaccurelative Jrag values are thought to “bereasonablyindspend.snt

44、cf turraeleffact and were therefore used.The smallest percentage increase tn profile-drag coef-ici,ertcaused at zero angle of attack .arrflflap deflec-tion by replaci,nthe plain flap with a flap withbalanced overhang was obta:ned with ths blunt-noseoverhangs. The lrcrease in cd rigedfnom 0.00060. .

45、. .- .,- ,r.7._,=,; .-.- ,-, -7-V-, -, ., . . . . . . . . . . - - -. . . , .;-., ,-., ,. .+: c,:, . . . .,:-;,. : . ,:- - . - -., -.”,.-”-. ., 7%/7w/2%Q 0.4(9C p%vf/p. F/cp qap, Q(M5c; tub, G20cf; tab qap, 12/Gq=o: ,Provided by IHSNot for ResaleNo reproduction or networking permitted without license

46、 from IHS-,-,-. .NACA ARR No. L5C01 Fig. 2 ConeoI-20 -/6 -12 -8 -4 0 4 8 1 16Anqle of attack, a., deg)Urg 2.- Cone/uO(ed.“ .- .- m.,- -. q m-y . -. ,-7 -, . . , ,.- - $ ,-:- ,- -.- .,-,-, . .,. -. - - - -, .,., . ., .: .-., .2 .?. .,. , :. . . . . . .Provided by IHSNot for ResaleNo reproduction or n

47、etworking permitted without license from IHS-,-,-,.NACA ARR No. L5C01 Fig. 3.,cwAnqle of aack, a., ctq “. . . -,. . .=. y . .-. . F-.- 7.-.-7-. - - , . . -, , y., , .-. , .,.! . -:, -. ;?, . . . . . . . . . . ., . ,“. - . . . “.,- mOdeghgure 5. -Concluded.-.-.-, - 7- -.-.:-.- ,-J ; v-r-,-.-.-l- - , , -. . . . ., :,.- -. - .,. . . . _-. . , , . . ;,- . . . ; , +.- .,-., ”: ., + :-.:., ., .,:, .,., ,-,. .-.” ,-. . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,