NASA NACA-ACR-3L20-1943 Wind-tunnel investigation of control-surface characteristics XV - various contour modifications of a 0 30-airfoil-chord plain flap on an NACA 66(215)-014 ai.pdf

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1、r*,” ,.,. .NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSORIGINALLY ISSUEDDecember1943asAdvanceConfidentialReport3L20WIND-TUNNELINVESTIGATIONOF CONTROL-SURFACECHARACTERISTICS. XV - VARIOUSCONTOURMODIFICATIONSOF A 0.30-AIKFOIL-CHORDPLAINFLAP(N ANNACA66(215)-014momBy PaulE. PurserendJohnM. RiebeLangleyMe

2、horialAeronauticalLaboratoryLangleyField,Va.NACAWASHINGTONNACA WARTIME REPORTS arereprintsofpapersoriginallyissuedtoproviderapiddistributionofadvanceresearchresultstoanauthorizedgrouprequiringthemforthewareffort.Theywerepre:“viouslyheldunderasecuritystatusbutarenowunclassified.Someofthesereportswere

3、nottech-nitallyedited.Allhavebeenreproducedwithoutchangeinordertoexpeditegeneraldistribution. .- 1A IA 1 IIi ,!, , ,L-668 LYflb A,LlJJAb3L* LANGLEY MEMORIALAERONAUlkfiLABORATORYLangley IT!eld, Va.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.*. ll

4、llll#j-.-._NA!TIONALADVISORY COMMI!I!TIilEFOR AERONAUTICS-.ADVAiYGE C01T3IDXN!lIAL REPOR!I!WIND-t7JNNJjjLINVESTIGATION OF CONTROL-SURFAC!ECIU.RAC!I?ERISTICSG, IUI VARIOUS CONTOUR 1u1ODIl?ICATIONS03A O.30AIRFOILCHORD PLAIN 3!LAPON AN NAGA66(215)014 AIRl?O”ILily Paul E. Purser and John M. RiebeSUMMARY

5、 “ “Force-testmeasurements in two-dimensional flowhave been made in the NAC?A4-by 6-foot vertical tunnelto d.etejminethe aerodynamic characteristics of an NACA66(215)-014 airfoil equipped with true-contour, straiqht-contour, and beveled-trailing-edge flaps having chordsZO percent of the airfoil chor

6、d. The results are pre-sented.in the form of aerodynamic sectio,ncharacteristicsfor several flap deflections and for a sealed and un-sealed gwp at the flap nose,The slope of the lift curve, the effectiveness ofthe flap, and the negative slopes of the hinge-momentcurves generally decreased as the tra

7、iling-edge anglewas increased, as the gap at the flap nose was opened,and as roughness was added to the Leading edge of theairfoileThe aerodynamic center of lift caused by changingangle of attack ruovedforward as the trailing-edge ang. owas increased and as roughness was added to the airfoilleading

8、edge. The aerodynamic center of lift caused %ychanging flap deflection tended to move forward when thetrailing-edge angle was increased and, when roughnesswas added to the airfoil leading edge, tendedto moverearward for the true-contour flap, to remain unchangedfor the straight-contour flap, ad to m

9、ove forward forthe leveled-trailing-edge flap.he effects of beveled trailing edges on the charac-teristics of a plain flap on a low-drag airfoil were notProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-,-2significantly different fron the effects previ

10、ouslynoted.for sinilar modifications on conventional airfotls.m!I!ItoDuc!210NAn extensive to-dimensional-flew investigation ofthe aerodynaulic section characteristics of airfcils withflaps has been undertaken hy the NACA to determine thetypes of flap arrangement best suited for use as controlsurface

11、s and to supply ezperiu.entaldata for design pur-poses. The investigation has included modifications offlap-nose shape, balancelength, and gap size on a %percent thick low-drag airfoil and on 9- and 15-percont-thick conventional airfoils, Other modifications haveinclued the use of a straight-contour

12、 fla and a _oeveld-trailingj-edgefla. The results of some of these ifives- a71tigations were reported i.nreferences 1 to .5. Reference6 has used the trailinedge angle of tilebeveled-trail-.ing-edge flap as a basis for correlation, .High-speed airplanes require the use of airfoilsections with low pea

13、k ressures , such as low-drag sec-tions, for tail surfaces to alleviate the d:,ngerof shockStallc In order to extend airfoil profile alterationsto low-drag airfoil contours, tests haq?ebeen made ofthe IfACUL66(215)-014 airfbil equipped with true-contour,fla+contour, and fieveled-trailin e flaps forv

14、arious flap deflections and _forIihegap open (Sigs. 4and 6) or for the gap closed (figs. !5and 7) have thosame general shape as the lift curves of the true-contourflap for the gap o-pan(fig. 2) or for tho gap closed(fig. 3). !Einogapoen,.and gap-sealed coditioashaodifferent flap deflecion ranes wh.e

15、rti whereast for the gap-sealed conditicn, thinonlinearity is most nGticeabla for the 15G and 20C fle,p .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.7.deflections. As the tratling-edge angle increases therange of flap deflections over which this

16、 noillinearityoccurs tends to become larger when the gap is sealedand to renain the same when the gap is open.!?heangle of attack at which the airfoil stalledtended to increaso slightly as the trailing-edge angleincfeased with the gap open but was approximately thesame with the gap sealed. A compari

17、son of figures 2 and3 with the data of reference 1 indicates that the liftcurves for various deflections of the true-contour flapfor both the sealed and unsealed gapon the NACA66(215)-014 airfoil are uore linear and indicate stalla% greater angles of attack than those of the TACA66-009airfoil.Slow o

18、f lift curves.- !l!heslope of the lift curve-(acl/a., for the true-contour flap was larger thanthat for the straight-contour or beveled-trailing-edgeflap with the sealed or unsealed gap. (See table ZI.)The decrease in .hYJ,f for the three flap contoursthat occurred with increasing trailing-edge angl

19、e nay beattributed to the increased thickness of the after por-tion of the airfoil, which caused an increased deviationin flow from the theoretical flow for thin airfoils. Adecrease in (ik,faq,falso occurred for the threeflap:contours when the gap was unsealed. This trendagrees qualitatively with th

20、e results for the I!T.4CA0009,0015$ and 66-009 airfoils (references 1 to 5).Effectiveness of flap.- The effectiveness of the-.- -fl?ps,(%O /W)cl was Greatest for the true-contour flap,and wa,spproximately the same with.the gap oth sealedand unsealed. As the trailing-edge anle increased$ theeffective

21、ness decreased; and unsealtng the gay furtherceduced the flap effectiveness (table 11).,.,With the gap unsealed, all.flaps testeclwere ,ef-fective in producing positive increments of lift at all .positive flay deflections within the unstalled range ofangle of attack. The flap effectiveness at zero a

22、ngleof attack and small flap deflections was greater with thegap sealed than with the gap unsealed, lut the incrementsProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.“8.of lift farthe high flap deflections with the ge.psealedwere very small or zero

23、in part of the negative anglc-ofattack range, Although a drop in effectiveness occurredat high flap deflections at negative angles of attack,the drop in effectiveness with flap deflection at thepositive angle of attack was not so pronounced for theEAGA 66(215)-014 airfoil as for the KACA 6S-009 airf

24、oil(reference 1) and 0015 airfoil (reference 5).Sloe of lift curves with controls fr+.- The parqm-.-Fter ac$/a%)cha =0 (table 11) ,isa measure of control-,. Lfreo stal;lity. !J!hosloe of the control-freelift curvewas less than that of the cotrolfid lift curve forthe irue-centour flap with the gap ei

25、ther sealed.or u,n-sealed. For the straight-contour flap the slope ofth lift curve with control freo was smaller than withcontrol fixed for the sqalcd gap; whereas no changeoccurred for the open gap. The slpe of the controlfrca lift cur-rewas larger than that of the control-fixedlift curve for the b

26、eveled-trailineiige flap, beinggroe.terwhen the gap was unsealed than when soalcd. Com-parison of the data for the three flap contours shows anincrease in (ac+h O with trailing-edge angle.It should be noted that these statements aro bLseerwith thegap sealed than with the gap unsealed, wero probably

27、theresult of fluw separation over the flap.Slope of hing-e+nament-curves.- !l!hehinge-ioment-._ - -parameters for the three flaF contours with the gapsealed and unsealed are given in table II. Because ofthe nonlinearity of the hinge-moment curve? over most ofthe angle-of-attack range, the parameter

28、(.achf/afwas measured at af = 0 0and a. = O over the linearrange previously.mentioned, Although this rango is small, Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-these values can he used for comparing the three flapcontours and for stability compu

29、tations.;howeveifor acomplete comparison the entire set of hinge-momntcurves must “00taken into consideration.straight-contour flap with the gap unsoalcd; hovj8fwas negative for the true-contour flax and was positivcshowing an overbalance for the bevele,d-trail.in-edeflap. (See figs. 8 and 9.) The v

30、alue ckf/?la&Fwas wore positive for the flaps with the larger trailinedge anles. This trend agrees qualitati.vel.%.with thedata of reference 4, hut the actual value of the ch,angeis larger than that indicated %y the curves of refer-ence 6.Values of the parameter (.achf/5f)ab (figs. 10and 11) were me

31、asured at flap deflections from 0 to 5because of the nonlinearity of the flap section hinge-rnomen% curves throughout the flap deflection range. Anincrease in trailing-edge angle produces a decrease inthe &egative value of (achf/b6f)ao for the gap sealedor unsealed (table 11). This trend also a?rees

32、with thedata of reference 4 but the actual values are againlarger than those indicated by the curves of reference 6.Effect of leading-edge rughness, Yho effect of-. .leading edge roughness on the variation of (bch#a&jf. J.and (acht/fmo with trailing-edge angle and gay con-dition for tho 0.30c flaps

33、on the NACA 66(215)-014 air-foil (fig, 16) was to make both chf/a&f andedge rou:”hneesdid not alter the gonoral tendency ofbchf/+f and (b.hf/a6f)ao to ecome more yositivwith increases in trailing-edge angle and wfth unseal-$ng tho gap.I!ftcctof Reynolds. number.- An increase in cffcctivo- .Reynolds

34、number from approximately 2,400,000 to 2,760,000slightly increased the negative value of bchf/&Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.11for the true-contour flap at 8f = 0 with the gapsealed (fig. i5)Q qedifferne in the values cf thebingo-m

35、omont coefficient at CLo= O“ proba%ly resulted.from errors in setting the angle of attack and flap do-flectionePitching HornentThe values of th.oparameters (acm/act)Go ma(acm/acl)f, shown in table II, give the yosition of theaerodynamic center with respect to the quarter-chordpoint. When the lift wa

36、s varied by changing tho angleof attack at a flap deflection of 0, the aerodynamiccenter of the smooth airfoil with a sealed gap was at0.25c for the true-contour flap, 0.22c for the straight-*contour flap, and 0.20c for the beveled trailing-edgeThis trend agrees qualitatively with the resultsflapin

37、reference 4. With roughness on tho leading edge, tko?aerodynamic center moved slightly forward to 0.24c forthe trucontour flap, to 0.21c for tho straight-contouriih&,tctcoiilgs:for tho bvelqd-”trailinedge flap. Un-sealing the gap genei”allyYladlittle effect on theposition of the aerodynamic center.

38、Increasing the ef-fective Ileyno$dsnumber had.very little effect on theaerodynamic center bf t:e airfoil with the sealed true-contour flap at f = O (fig. 15).The following table gives the position of the aro-iiynamiccenter of lift due to flap deflection:USL:3 Aerodynamic centerLeadingedge rue-!etour

39、 =:-0.002a Sealed 0.002c lSealed a71 -J :gap gap gap gapI6mooth 0,43CI0*41C 0.43CRough .c .44C .43C 42si_ isWith roughaess on the leading edge, the aerodynamic,center of lift caused by flap deflection moved rearward .Provided by IHSNot for ResaleNo reproduction or networking permitted without licens

40、e from IHS-,-,-.12about 0.03c fOr the true-contour flapf remained un-changed for the straight-contour flap$ zmd timed 0.02cto 0.03c forward for the beveled.-trailing-edge flap.Yhe position of the aerodynamic center of lift caused 327flap deflections is a function of the aspect ratio (ref-erence 10)

41、and moves toward the trailing edge as theaspect ratio decreases. It can be seen that, if theaerodynamic-center positions are plotted againstchf/%&f a chf/a5f)a0 there is a general trendfor tho aerodynamic centers to move forward as theslopes ofthe hinge-moment curves become moro positivo+Drag .Becau

42、se the turbulence of the 4- IIY6-foot verticaltunnel made it impossible for the low-drag condition tcbe roalizcd on the NACA 66(215)-014 airfoil and hocausof tho unknown tunnel correction, the measured Talues ofdrag cannot be considered absolute and are not presentedin the FeeSent report. The increm

43、ental Values, however,should be reatively independent of tunnel effect, NACAWASHINGTONNACA WARTIME REPORTS arereprintsofpapersoriginallyissuedtoproviderapiddistributionofadvanceresearchresultstoanauthorizedgrouprequiringthemforthewareffort.Theywerepre:“viouslyheldunderasecuritystatusbutarenowunclass

44、ified.Someofthesereportswerenottech-nitallyedited.All havebeenreproducedwithoutchangeinordertoexpeditegeneraldistribution. .- 1A I A 1 II i ,!, , ,L-665 LyflQ A blill* LANGLEY MEMORIAL AERONAUlkfiLABORATORYLangley IT!eld, Va.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-