NASA NACA-TN-4185-1958 Wind-tunnel investigation of effect of sweep on rolling derivatives at angles of attack up to 13 degrees and at high subsonic Mach numbers including a semiemvati.pdf
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1、NATIONALADVISORYCOMMITTEEFORAERONAUTICSTECHNICAL NOTE 4185WIND-TUNNELINVESTIGATIONOF EFFECT OF SWEEPONROLLINGDERIVATIVESAT ANGLESOF ATTACK UP TO 13 ANDAT GHSUBSONICMACHNUMBERS, INCLUDINGA SEM3,EMPIRZCALMETHODOF ESTIMATINGTHE ROLLINGDERIVATIVESBy JamesW. WigginsLangleyAeronauticalLaboratoryLangleyFie
2、ld, Va.WashingtonJanuary1958s3.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NMT.,-.P.,NATIONALADVISORYCOMMITIEETECHNICALNoTEI!llllllllllllill;ll!FORAERONAUTICSUClwhereasa stableconditionisindicatedonlyattheextremeratesofroll.Theres
3、ultspresentedinfigureU showthat,ofthewingsinvestigated,tl.d.splanformshowedunfavorabledamping-in-rollcharacteristics(indicatedby C overthelargest. testrangesofMachnumberandangleofattack.thatis,zeroorslightlynegativevaluesareobtainedattheloweranglesofattackandpositivevalues. areobtainedatthehighertes
4、tanglesofattack.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8“Infigure13, thevariationsented.Negativevaluesof pof CyP withangle(lateralforcedueindicatedatthehighertestanglesofattackandatNACATN4185ofattackispre-torolling)aremostMachnumbersforallco
5、nfigurationstested.A discussionandpossibleexplanationofthebehaviorof Cnp and Cy throughthetestangle-of-attackandMachPnumberremgeandamethodforestimatingthesederivativesarepresentedinthefollowingsection.EstimationsofRollingDerivativesRollinRmomentduetorolling.-A comparisonoftheexperimentalhowever,thee
6、xperi-mentalandpredictedvaluesshowsimilartrends.Yawinamomentduetorollinz.-Inreferences14and15,methmlserepresented”orthepredictionof Cnp throughanusingcorrespondingexperimentaldragdata.Thehasbeenshowntopredictp throughthetestangle-of-attackrangemethodinreference14angle-of-attackrange .Provided by IHS
7、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-2T NACA.with.*enceTN4185 9considerablybetterresultsthanthemethoddescribedinrefer-1. Thisresultisprobabwduetothefactthatthemethodofref-erence15predicts%p yetirapolatingfromthepotential-flowtheorybyuseofexperimentaldrag
8、dataandanempiricallydete?hinedfactorthatisproportionaltoadrsg-centermomentarm;whereastheprocedureofreference14predictsCn byusingtheexperimentaldragdatatoPproportion%p relativetotwolmownconditions.Briefly,themethodofreference14consistsofproportioningp relativetotheconditionofpotentialflowwheretheresu
9、ltantforceisnormaltotherelativewindandtotheconditionforwhichtheresultantforceisnormaltothewingchord.Anequationispresentedtheretiforevaluat Cnp fortriangdsrwings.However,forotherwingplanforms,thisequationmustbenmdifiedasfollows:thepotential-flowvalueof p fortriangularplanforms(ref.16) mustbereplacedb
10、ythevalueforwingsoftaperratiosotherthanO,andanadditionalterm,showninreference15forlow-aspect-ratiowhgs tobearesultofwing-tipsuction,mustbecon-sidered.Withtheseconsiderationsapplied,thefollowingeqmtioncanbewritten:a71(C%=-CZptsna-K-CZp tanm- )()b% + Cnp (1)CL tip suctionwherethepotential-flowvaluesof
11、 p/ canbedeterminedfromref-erence17aneitherexperimentalorchowever,thisresultisnotsurprisinginasmuchastheexperimentalvaluesof Cyp fortheunsweptwing(which=e dueprimarilytotipsuction)presentedinfigure17indicatethat,withinthetestrangesofMachnumberandangleofattack,thetip-suctioncontributioncanbeneglected
12、.ThedataforaMachnumberof0.15(fig.17)wereobtainedfromreference18.Theleading-edgecontributionto Cnp wouldbeexpectedtovary.considerablywithleading-edgeradii;consequently,infigure21low-speedProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N(4CAm 4185 IL.r
13、esultssrepresentedfor12.percent-thickwings(ref.19)whoseleading-.-1 edgeradiivsryfroma verysharpone to a very bluntone. Thewingsreportedinreference19hadanaspectratioof2.61, a taperratioof1.0,and450sweepback.A comparisonofexperimentalp withcal-culatedvaluesevaluatedbyuseofequation(1)ispresentedtifigur
14、e22forthewingsofthepresentinvestigationatvariousMachnmberswherebothexperimentalandcalculatedvalusof Ctp wereused;thetip-suctioncontributionto C9 wasassumedtobeO. Theagreementiscon-sideredgoodforallwingstestedwhereeitherexperimentalorcalcu-latedClp areusedinequation(1),andtherestitspresentedinfig-ure
15、s21and22indicatethatthepresentmethodofestimatingCnp(eq.(1),withouttip-suctioneffects)isapplicableoverlsrgersngesofleading-edgeradii,wingthickness,andsubsonicMachnumbers.Lateralforceduetorolling.-Anexpressionfordeterminhg Cypforthepotential-flowcasecanbeobtainedfromreference17andwrittenas.4and,forthe
16、nonpotentialthewingchordplane,Cyp= CL A+cosA t=AA+kcosAcase,whentheresultantforceisnormaltowouldbeeqwl toO. Byconsideringthetip-suctioncontributionandbyapplyingthefactorK,theequationcanbewrittencYp (=K )+cOsA tanA +A+4COSAwherethetipcontributionto Cyp canbe() (2)p tipsuctionexpressedas()CYP %=tipsuc
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