1、,:Iw(30 .I Ih%1rNATIONALTECHNICAL NOTE 2440WIND-TUNNELINVESTIGATIONANDANALYSISOFTBEEFFECTSOFENDPLATESONTHEAERODYNAMICCHARACTERLSTICSOFAN UNSWEPTWINGByDonaldR. RileyLamgley AeronauticalLaboratoryLangleyField,Va.WashingtonAugust1951.- . - - . +.,- .-. - - - - . .-. . -.- - ._. .-. ,. - .Provided by IH
2、SNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NMIulinlllnllillllu1 NATIONALADVISORYCOMMITTEEFORAERONAU3%0OUL5b73oTECHNICALNOTE2440WIND-TUNNELINVW15BATIONANDANAJXSISOFTHEEFFECTSOFENDPIATESONTHEAERODYNAMICCHARACTERISTICSOFANTJNSWEl?J7WINGByDonaldR.
3、RileyA wind-tunnelinvestigationhasbeenconductedtodeterminetheeffectsofendplatesofvariousareasandshapesontheaerodynamiccharacteristicsofanunsweptanduntaperedwingofaspectratio4.Theresultswereinagreementwiththoseofpreviousinvestigationsinthattheendplatesprovidedthebasicwingwithanticreaseinthelift-curve
4、slope,a reductionintheinduceddrag,andanincreaseinthemaximumliftcoefficient.Negligiblevariationswereobtainedtithepitchingmomentwhentheendplateswereadded.A reductionoftheexper-imentaldata,inwhichtheend-plateeffectwaseqresaedintermsofaneffectiveaspectratio,wasinfairagreementwiththeclassicaltheoryforeva
5、luatingtheend-plateeffectsonthelift-curveslopeandinduceddrag.Expreflsionsforthelift-dragandmatiumlift-dragratios,devek”pedhereinforthewing-end-plateconfiguration,gavepredictiothatCODI.paredfavorablywithexpertientalvalues.A theoreticalanalysisofthesetwuexpressionsindicatesthattheuseofendplatesmayprov
6、iderelativelykrge increasesinthelift-dragratioatthehigherliftcoefficientsfora limitedrangeofend-plateareasbtithatendplatescannotbeexpectedtoprovidesubstantialincreasesinthemaxtiumllft-dragratioofthewing.Themostfavorableeffectofendplatesonthemaximumlift-dragratioofawingisobtainedwhenthewingaspectrati
7、oislowandtheratioofwingprofiledragcoefficient-toend-plateprofiledragcoefficientishigh.Forsuchcases,however,theabsolutevalueofthemaximumW-drag ratiois,ofnecessity,ratherlow.tithecaseofwing-bodycombinationsorcompleteairplanes,forwhichthetotaldragofcomponentsotherthanthewingmaybelargerelativetothewingd
8、rag,substantialincreasesinmaximumlift-dragratioapparentlymaybeobtainedbytheuseofappropriatelydesigned- . . .y .- - - . -. -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACATN2440Qendplates.TheincreaseobtainedwifiendpktesjexcePtPosihlYforsmallend
9、plates,isnotWeW tobe aswj heveryastt whichwouldbeobtainedbyutilizingtheend-plateareaasa simpleadditiontothewingtipstoincreasethewingspanandhencethewinggeometricaspectratio.Theuseofendplatesasameansofroving theMft-dragratiosofairplanes,therefore,wod seemtobeofPr_ Por-tancewhenitisdesiredtokeepthewing
10、spanassmall.aspossible.Theuseofendplates-c characteristicsofences1 to5. TheresultsplatesprovideanincreaseINTRODUCTIONasapossiblemeansofimprovingtheaero-unsweptwingshasbeeninvestigatedinrefer-oftheseinvestigationsindicatethattheendinthelift-curveslope,areductionintheinduceddrag,andanincreaseinthemaxi
11、mumliftcoefficientofthebasicwing.Heretofore,theoreticalandempiricalanslysesonend-plateeffectshavebeenconcernedmainlywithpredictingthelift-curvesloPeandtheinduceddragand,asaresult,haveyieldedrelativelyfewcon-clusionsontheeffectofendplatesonthelift-dragandmaximumlift-dragratios.Thefavorableeffectsofen
12、dplatesontheliftandinduceddraghavesuggestedthepossibilityofusingendplatesasameansofincreasingthelift-dragandmaxbnumlift-dragratiosofthebasicwing.Theeffectofendplatesonsweptbackwingshasalsobeeninvestigatedandtheresultsarepresentedinreference6.ThepresentinvestigationwasconductedintheLangleystabili .)t
13、unneltodeterminetheeffectsofendplatesofvariousareasandshapesontheaerodynamiccharacteristicsofanunsweptanduntaperedwingofaspectratio4. Theresultsservethepurposeofcheckingthevalidityofcurrentmethodsofpredictingtheend-plateeffectonthelift-curveslopeandtheinduceddrag.Inaddition,expressionsaredevelopedhe
14、reinforthelift-dragandmsximumlift-dragratiosandthecalculatedresultsarecomparedwithvaluesobtainedfromtheexperimentaldata.A theoret-icalanalysisofthelift-dragandmaximumlift-dragratiosispresentedinordertoindicatetheinfluenceofthevsriousfactorsaffectingthesetwoaerodynamiccharacteristics.SYMBOLSThedatapr
15、esentedhereinsreintheformofstandsrdNACAcoeffi-cientsofforcesandmomentswhicharereferredtothesystemofwindaxeswiththeorigincoincidingwiththeintersectionofthewingquarter-chordlineandtheplaneofsymmetry.Thecoefficientsandsynibolssredefinedasfollows:.“- -Provided by IHSNot for ResaleNo reproduction or netw
16、orking permitted without license from IHS-,-,-NACATN2440 3.r LDMCLCDcmL/D(L/D)Eclift,poundsdrag,poundspitchingmoment,foot-poundsliftcoefficient(L/q)odragcoefficient(D/qS,whereS isreferenceareaequaltowingareaunlessotherwisenoted)pitching-momentcoefficient(M/qlift-dragratiomaximumlift-dragratiomaximum
17、liftcoefficientcL(L/D)= liftcoefficientatwhichlift-dragratioisamaximumCD% profiledragcoefficientCD end-plateprofiledragcoefficientbasedonend-plateareaepC150epend-plateprofiledragcoefficientbasedonwingareaMD incrementalinterferencedragcoefficientduetojuncturebetweenwingandendplatesc% parasitedragcoef
18、ficient(assumedtobedragcoefficientrepresentinganycomponentpartsofanairplaneotherthanwingandendplates,suchasa fuselage)q free-streamdynamicpressure,poundspersquarefoot()1 22PP massdensityofair,slugspercubicfootv free-streamvelocity,feetpersecondSw wingarea,squarefeet- .-. .- .- . ._. Provided by IHSN
19、ot for ResaleNo reproduction or networking permitted without license from IHS-,-,-iWCATN2440cbsepsand,inaddition,atheoreticalanalysisof L/D and (L/D)H isincludedtoindicatetheeffectofvsryingthefactorsthatinfluencethesetwocharacteristics. TESTRESULTSGeneralRemsrksFromthedataobtainedfromthewind-tunnelv
20、sluesfortheaerodynamiccharacteristicsCL,L/Dj(L/D)=,and cL(L/D)= wereevsluated.Itisdesirabletoknowtowhatextenteachofthesecharacteristicsisaffectedbytheadditionofendplatestothewingandwhatvariationsintheendplatesthemselvesproducechangesinthevaluesofthesecharacteristics.Someoftheend-platevariationswhich
21、mayinfluencetheaerodynamiccharacteristicssre(1)end-plateprofile(crosssection),(2)end-plateplanform(shape),(3)locationofend-plateareawithrespecttothewingchordline(mtric, al-labove,orallbelow),and(4)end-platearea.Theseend-platevariationssrediscussedinthissectionofthepaperandapplyforthemostparttoendpla
22、teshavingtheirareadistributedovertheenttiewingchord.Theeffectsofusingpsrtialendplates(endplateshavingtheirareadistributedoveronlyaportionofthewingchord)andendplatesextendingbeyondthewingleadingandtrailingedgesarediscussedinthepartofthepaperentitled“GeneralizedAnalysis.”.BasicDataThelift,drag,andpitc
23、hing-momentcharacteristicsforthewingaloneandincombinationwiththevariousendplatesarepresentedinfigures4and5. Thedataexhibittheusual.characteristicsassociated . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NM!ATN2440 7withendplates,suchasanincreasei
24、n ca and C andareduction.inthedragcoefficientatallliftcoefficientsabovea certainminhum.Belowthisminimum,thedragcoefficientindicatesanincreaseoverthatofthe%asicwing.Inthislow-lift-coefficientrange,however,theadditionaldragduetotheendplatesiseaterthananyreductionintheinduceddragthattheymayproduce.Thel
25、iftcoefficientatwhichthebeneficialeffectsoftheendplatesfirstbegintooccurappearstobea functionofend-platemea. Theseliftcoefficientsforthevariouswing-end-platecombinationstestedvaryoverarangefrom0.35to0.64,thehigherliftcoefficientsbeingassociatedwiththelsrgerend-plateareas.Alltheend-plateconfiguration
26、stestedproducedanincreaseinCL and C* ofthebasicwing.Theend-plateinfluenceonthesetwocharacteristicsisdiscussedinthefollowingsectionsofthepaperandcanbeneglectedhere.Thestaticlongitudinalstabilitycharacteristicsof.thevariouswing-end-platecombinationsshowa slightvariationfromthestabilitycharacteristicso
27、fthewingalone.Theti withtheV=iOUSSyUlmetriCdendplatesattachedshowsa slightincreaseinstabilityoverthebasicwing.ThewingincombinationwiththeendplateshavingtheirareaWabovethewing,withtheexceptionofendplatesJ,exhibitslessstabil-itythanthebasicwing.Althoughthepercentagechangesarelarge,theabsolutevaluefore
28、achseparateconfigurationissmallanddoesnotappeartobeimportant.Figure6presentstheexperimentalvaluesof L/D forthewingaloneandinconibinationwiththevsriousendplatesasa functionof CL. A comparisonofthedataindicatesthat821theconfigurationswithendplatesproducedamuchlowervalueof (L/D)m thanthewingalone.Thead
29、ditionofendplatesalsoincreasedtheliftcoefficientatwhichthemaximumvalueof L/D occurredandproducedvaluesof L/Datorneaxthemaximumoverawiderlift-coefficientrange.Experimentalvaluesforalltheaerodynamiccharacteristicsunderconsiderationwe availablefromthefigWesPreciouslydiscussedexceptWDifortheslopeofthein
30、duced-dragcurve. Inordertoobtainvalueshowever,thewingprofiledragcoeffi-cientwasobtainedbycalculatingtheinduceddragforanaspect-ratio-4airfoilandsubtractingitfromtheexperimentaldataforthewingslone.CL2,whereuTheexpressionusedfortheinduceddragwas isthemucorrectionfactorforaspectratioandtaperratioandcanb
31、eobtainedfromreference8. A comparisonofthewingprofiledragcoefficientcalculatedinthismannerwiththesectiondragcharacteristicsofanNACA641-4wairfoilsection(reference9)ataReynoldsnuuiberof1x106ispresentedinfigure8. Thefigure.indicatesthatthevaluesareInfairlygoodagreementexceptatthehigherliftcoefficients.
32、Somevariationisapparentinthevaluesof % intheregionofthedragbucketandintherangeofliftcoefficientscoveredbythedragbucket.Thesetwovariations,however,arebelievedtobetheresultofa smallsmountofturbulencepresentintheairstreamoftheLangleystabilitunnel.Thetwoairfoilsectionsareidenticalexcept.thattheNACA6-412
33、hasa smalltrailing-edgecusp,whereastheNACA6A412 .hasthecuspremoved.Noattemptwastie inthepreviouscalculationstoremovethedrag .oftheendplates.Theend-platedragwasbelievedtobefairlyindepend-entofliftcoefficientandhencewouldnotmateriallyaffecttheslopesofthecurvesinthelow-andmedium-lift-coefficientrange.T
34、helinearvariationobtainedfor CD-% belowa CL2 of0.35(seefig.7)forallthewing-end-plateconfigurationsenabledthedeterminationof aq)-i%iFigure7 alsoindicatesthat varieswiththeendplatesacL“ L2testedandapparentlyisa functionofend-platemea (fore=mple,com-parethewingwithendplatesF,G,andH).Experimentalvsluesf
35、orthevariousaerodynadccharacteristicsofeachofthewing-end-plateconfigurationstestedwereobtainedfromthefigurespreviouslydiscussedandsrelistedintableI. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACATN24-40 9- EffectofEnd-PlateProfile.Theeffecto
36、fend-plateprofileorcrosssectionontheaerodynamiccharacteristicsofwing-end-plateconfigurationscanbeobtainedbycomparingtheexperimentalresyltsforthewingwithendplatesG andI attached.EndplatesG andIvsryonlyintheshapeoftheend-platecrosssection.EndplatesGhaveroundedleadingatitrailingedgeswhereasendplatesIwe
37、reconstructedwithroundedleadingedgesandsharptrailingedgessoastosimulateanafoilcrosssection(fig.2). Mostoftheinfluenceofend-plateprofilewouldbeexpectedtooccurinthe.drag.A comparisonofthedragcharacteristicsforthetwoconfigurations(seefig.5)indicatesthatthewingwithendplatesI hasthereductioninthedragwith
38、respecttothewingaloneoccurringatalowerliftcoefficientthanthewingwithendplatesG. Inaddition,thewingwithendplatesIhasa smallerincreaseinthedragcoefficientwithrespecttothewingaloneforthelow-lift-coefficientrange.Ifonlyforthetiprovementinthedragcoefficient,thesimulatedairfoil-shapedendplateshaveprovedth
39、eirsuperiority.EndplatesI alsoaffectedL/D andprovideda slightlyhighervalueof (L/D)=xthanwasobtainedwithendplatesG.wereslightlylowerforthewingA sbilarindicationcanbea% Valuesof _ ad CL*L2 (L/D)WwithendplatesI.obtainedbycompsringthedragpol=sforthewingwithendplatesK andO (fig.5). Theendplatesvaryonlysl
40、ightlyinshapeandarea;however,anexactcomparisoncannotbemadeasinthecaseofendplatesG andIbecauseendplatesO extendedbeyondthewingleadingandtrailingedgesandendplatesK didnot.Nevertheless,thebeneficialeffectofusinganairfoilsectionfortheend-plateprofileisapparent.Theresultsofthesecompmisonsclearlyindicatet
41、hatusingair-foilshapesasend-platecrosssectionsishighlydesirable.Thisfactwasalsopointedoutinreference2.EffectofEnd-PlateAreaTwoseriesofendplatesareavailableforindicatingtheeffectofend-plateareaontheaerodynamiccharacteristicsofwing-end-plateconfigurations.EndplatesF,G,andH,whichcompriseoneseries,havet
42、hesamelocationofend-platearearelativetothewingchordline,.thessmeplanform,andthesamecrosssectionod.ytheend-plateareaisvaried.Theseparticularendplatesseemtobethemostlogicalchoiceforindicatingtheeffectsofend-platearea.Sincethechord._ _. . . - .Provided by IHSNot for ResaleNo reproduction or networking
43、permitted without license from IHS-,-,-10.foreachoftheseparticularendplatesisequaltoincreaseinareaisobtainedbyactuallyincreasingIncreasingtheareainthismanner,asisindicatedNACATN2440“thewingchord,thetheend-plateheight. a71subsequently,appearstobethemostlogicalwayofincreasingtheend-plateeffect.Theothe
44、rs$ries,consistingofendplatesA,B,andD,hasessentiallythessmeend-platecrosssection;however,thelocationoftheareawithrespecttothewingchordline,theplanform,andtheend-plateareaarealldependent?nthecalculatedstatic-pressurevariationchosenfortheparticularendplate(seesectionentitled“ModelandApparatus”).Bothse
45、riesofendplatesareindicatedinfigure9,whichpresentstheexperimentalresultsoftheeffectofend-platiareaontheaero-dynamiccharacteristicsCL, *D, C, (L/D) - cL(L/D)Wa L2fasafunctionof SepSw. Increasingtheend-plateareaprovidesanincreasein CLa, C%, %m cL(L/D)= anda decreasein -however,thecalculatedshapesa%mor
46、efavorablevaluesfor CLaj -, a (L/D)H thantheL2rectangularshapes.Onlya slightdecreaseisapparentin CL(L/D)uforthecticulatedshapesatthelargerend-plateareasandtheinfluenceon C% appearstobenegligible.Ingeneral,thecalculatedshapesseemtoprovideslightlymorefavorableresults;however,theimprovementobtaineddoes
47、notseemsufficienttowarrantadeparturefromthemoresimplegeometricshapes.EffectofEnd-PlatePlanFormandLocationofEnd-PlateAreaRelativetotheWingChordLineTheeffectofend-plateplanformandlocationofwithrespecttothewingchordlineontheaerodynamicofwing-end-plateconfigurationscanbeseeninfigureplatespresentedinthis
48、figurehaveapproximatelytheessentiallythesamecrosssection;thatis,roundedleadingandtrail-ingedges.Inaddition,theend-plateareawasdistributedovertheentirewingchordbutwasnotpermittedtoextendbey thewingleadingandtrailingedges.end-plateareacharacteristics10. All theendsameareaand. . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-, NACATN2440 HA comparisonofexperimentalresultsforthewingwithendplates.G,J,andM attachedindicatesthattheeffectofthelocationofend-pl
