1、tIL.NATIONALADVISORYCOMMITTEEFORAERONAUTICSTECHNICAL NOTE 3551EXPERIMENTALINVESTIGATIONAT LOW OFEFFECTSOFFUSELAGECROSSSECTIONONSTATICLONGITUDINALANDLATERJ4LSTABILITYCHARACTEKWTICSOFMODELSHAVING0 AND45 SWEPTBACKSURFACESByWilliamLetkoandJamesL. WilliamsLangleyAeronauticalLaboratory. LangleyField,Va.0“
2、WashingtonDecember1955AFwx . . . . . . . . . . . . . . . . . . . . y. _-_A z _1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-vNATIONALADVISCSRYCCMMTTEEFORAERONAUTICSzizii:DCILLL72TECHNICALNOTE3551EXPERIMENTALINVESTICXTIONATLOWSPEEDOFEFFECTSOFFUSEIA
3、GECROSSSECTIONONSTATICLONGITUDINALANDLATERALE3!ABIIlTYCHARACTERISTICSOFMODELSHAVING0AND45SWEPIBACKSURFACESByWilliamInottheleastoftheseistheairplanefuselage.Variousjet-engineinstallationsinfuselagesandinwing-fuselagejunctureshaveresultedinavarietyoffuselagecross-sectionalshapes.Althoughtherearenumero
4、usdataonconfigurationswithbodiesofcircularcrosssectionsuchasthosepresentedinreferences1,2,and3, littledataofsystematicnatureareavailableforothershapes.- . . _ _ . _ . _ _ _ _ -_ _Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACATN3551Inordertopr
5、ovidedataontheeffectoffuselagecrosssectiononairplanestaticlongitudinalandlateralstabilitycharacteristics,severalfuselageswithinterchangeablewingandtailsurfaceshavebeentestedintheIa.ngleystabilitytunnel.Thefuselagestestedwereofround,square,andrectangularcrosssections.Thefuselagesofsquareandrectangula
6、rcrosssectionshadroundedcorners.ThewingsandtailstestedsuccessivelyonthefuselageshadOoand45sweepback.Alltheconfigurationsweretestedwiththewinginthemidwinglocation.Pre-sentedhereinarethestaticlongitulisticsoftheseconfigurations.SYM1301Saudlateralstabilitycharacter-Thedatapresentedarereferredtothestabi
7、litysystemofaxeswiththeoriginattheprojectionontheplaneofsymmetryofthecalculatedaerodynamicandangularsymbolsareCLCDCyclcm%LDFyMxMycenterofthewing.Positivedirectionsofforces,moments,displacementsareshowninfigure1. Thecoefficientsanddefinedasfollows:liftcoefficient,L/qSWdragcoefficient,D/qlateral-force
8、coefficient,FY/Wrolling-mmnentcoefficient,%pitching-momentcoefficient,MY/wyawing-momentcoefficient,/qswbwliftdraglateralforcerollingmomentpitchingmomentMZ yawingmoment . .- - . -. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3551q dynsmicpre
9、ssure,2v free-streamvelocityP massdensityofairA aspectratio,b2/Sb span,measuredperpendiculartofuselagecenterlines surfaceareac chord,measuredparalleltoplaneofsymmetryCr rootchord “Ct tipchordE meanaerodynamicY coordinatealongI/2chord;forexample,6W=% cW2dyY-axis,measuredfromplaneofsymmetrylv or ZH ta
10、illength,distanceel tO.fUSee centerlinefrommountingpointto %# r H/4h perpendiculardistancefromfuselagecenterlineto Ev/4(tailrootchordcoincideswithfuselagecenterline)R ordimteofcircularfusehger fuselagecornerradius,R/3w localhalf-widthofd localhalf-depthofsquarefuselage,squareorrectangularfuselagesqu
11、areorrectangularfuselage;ford=wlongitudinal-distancealongfuselagecenterlinetaperratio,% Icrangleofsweepbackofqyarter-chordline,degangleofsideslip,deg.- . -_ _ . _ - . . . . . ._. _Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3551azimuthangle
12、,degangleofattack,deg.ACyPAdnP contributionofthetailgrouptoderivatives;thatis,forthewingon,forACYP= (cyP)w+F+v+H()- cyW+Fthewingoff,ACY = () (5)CypF+.V+H- FBforawing-tailconfiguration,A% =P (%) (%)W+V+H- PWSubscriptsandabbreviations:F fuselage;usedwithsubscripts1to4todenotevariousfuselages(seefig.2)
13、H horizontaltail;usedwithsubscripts1 and2 (seefig.3)v verticaltail;usedwithsubscripts1to6todenotevariousverticaltails(seefigs.3 and4)w wing;usedwithsubscripts1and2 (seefig.3)J.- - - .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 3551APPARKTU
14、SANDMODELS5Thetestswereconductedinthe6-by6-foottestsection”oftheLangleystabilitytunnel.Themodelsweredesignedtopermittestsofthewingalone,thefuselagealone,thewing-fuselagecombination,orthefuselagewithanytailconfigurationwithorwithoutthewings.Drawingsofthecomponentpartsofthemodelstestedaregiveninfigure
15、s2to4 andintableI.A sideview,.crosssection,anddesignationofeachfuselageisgiveninfigure2. Thecoordinatesofthecircular-cross-sectionfuselagearegivenintableI. Thecoordinatesofthesquareandrectangularfuse-lagesweredeterminedsothatthevariationofthecross-sectionalareaofeachfuselagealongthelongitudinalaxisw
16、asthesameasthatofthecircularfuselage.TheequationsusedtodeterminethecoordinatesofthesqyareandrectangularfuselagesaregivenintableI. Therectangu-larfuselagewastestedbothwiththemajorcross-sectionalatisvertical(fusekge3)andwiththemajoraxishorizontal(fuselageJ). (Seefig.2.)Theconfigurationshadbothsweptand
17、unsweptwingandtailsurfaces.Thequarter-chordlinesweresweptback0and45fortheunsweptandsweptbacksurfaces,respectively.Thewingshadataperratioof0.6andanaspectratioof4. Thetailsurfacesalsohadataperratioof0.6.Theaspectratioandothergeometriccharacteristicsofthevarioustailsurfacesaswellasthoseofthewingscanbef
18、oundintableII.Drawingsshowingthegeometriccharacteristicsofthewingandtailsur-facesaregivenasfigures3and4. Alltheconfigurationsweretestedwiththewinginthemidwinglocation.Allliftingsurfacesweresetat0incidencewithrespecttothefuselagecenterline.Themodelsweremountedona singlestrutsupportatthequarter-chordp
19、ointofthewingswhichwerelocatedwithrespecttothefuselageandtailsurfacesasshowninfigure5. Fortestsofthecomplete-modelandfuselage-tailconfigurations,theverticaltailwasmountedsothatthevertical-tailroot-chordlinecoincidedwiththefuselagecenterline.Forthewing-tailconfigurations,thetailwasmountedatanappro-pr
20、iatetaillengthona steeltubeofsmalldiameterwhichwasfastenedtothewing.Theisolatedtailwasmountedonthesametubewhichwasthenattachedtothemodelsupportstrut.Forthewing-tailandisolated-tailtests,thetailareaincludedtheportionnormallyenclosedinthefuselage.Forcesandmomentsweremeasuredbymeansofa conventionalsix-
21、componentmechanicalbalancesystem.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 NACATN3331.TESISANDCORREKZIONS .Testsweremadeata dynmicpressureof24.9poundspersquarefoot,whichcorrespondstoaMachnumberofabout0.13andaReynoldsnumberofabout0.71x 106base
22、donthemeanaerodynamicchordofthewings.Themodelsweretestedthroughanangle-of-attackrangefrom“ uptoandbeyondmaximumlift(ofwingsalone)atanglesofsideslipof0and*5.Testsofthecompleteconfigurationwerealsomadeatanglesofattackof0,10,20,and26througha sidesliprangefrom-20to20.Approxhhowever,theunstablecontributi
23、onofthecircularfuselageislessatthehighanglesofattackthanthatofthesquarefuselage.Theshallowfuselage(fuselage4)hasthehighestliftanddragatthehighanglesofattack.Addingthetailunittothefuselagesresults,ofcourse,instablepitching-momentcurvesatthelowanglesofattack(fig.9). Thecon-figurationwithshallowfuselag
24、eandtailistheleaststable.Forallfuselagesandfortheunswepttail,theslopeofthecurvesof plottedagainstu ispracticallyzeroatthehighanglesofattackforthetestcenter-of-avityposition.wing, tail,andwing-tailconfigurations.-characteristicsofthewing,isolatedtail,andaregiveninfigure10. ThedetailspertainingThelong
25、itudinalstabilitywing-tailconfigurationstothemountingofthe . . ._Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8tailforentitledTheNACATN 3551thewing-tailandisolated-tailtestsaregiveninthesection“ApparatusandModels.”sweptandunsweptwingsusedinthepres
26、entinvestigationhavebeenreportedoninseveralotherinvestigationssuchasreferences5,6,and7,andthereislittleneed,here,todiscussindetailthechar-acteristicsofthewings:Figure10showsthataddingthewingtotheisolatedtailcausesadecreaseinlontudinalstabilityatlowanglesofattackwhichismuchlargerfortheunsweptwingthan
27、thatobtainedwiththeswept-wingcon-figuration.Thedecreaseinlongitudinalstabilityobtainediscausedbywingdownwash.Forboththesweptandunsweptconfigurations,thegeneralvariationofpitching-momentcoefficientwithangleofattackforthewing-tailcom!?igurationisverysimilartothevariationobtainedforthecompleteconfigura
28、tions.Forthecompleteconfigurationsthereis,ofcourse,a differenceininitialslopesatlowanglesofattack,mainlybecausetheunstablecontributionofthefuselagevarieswiththefuse-lagecrosssection,StaticLateralStabilityCharacteristicsCompletemodel.-ThestaticlateralstabilityderivativesCyPj,Czp,and CnP (obtainedfrom
29、dataat =*5)forthecompletemodelcon-figurationsaregiveninfigureIl. Forboththesweptandunsweptmodels,thereislittledifferenceinthevaluesof CnP fortheconfigurationswiththecircularorsquarefuselageatlowangiesofattack.However,thevaluesof CnP obtainedfortheconfigurationswithshallowfuse-lage(fuselage4)wereappr
30、eciablygreater(indicatinggreaterdirectionalstability),andthevaluesof CP forthedeep-fuselageconfigurationwereappreciablylessthanthoseobtainedforthecircular-andsquare-fuselageconfigurations.Thisdifferenceinthevaluesof attheBlowanglesofattackcanbeattributedmainlytothedifferenceinthefuselagecontribution
31、s.Exceptforthedeep-fuselageconfiguration(W1+ F3+V1+ Hi),thevaluesof CnP arepositiveandfairlyconstantthroughouttheangle-of-attackrangefortheunsweptmodels.ThevaluesOf Cnp for”thedeep-fuselageconfigurationarepositiveuptoanangleofattackofabout20afterwhichCn becomesnegative.ThesweptBconfigurationshavepos
32、itiveandnearconstantvaluesof Cn through-t3outthelowanglesofattack.Forallfuselageconfigurations;%becomesnegativeatthehigheranglesofattackandremainsnegativeforProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3551 9thetestangle-of-attackrangetionwh
33、ichhaspositivevaluesexceptforthesquare-fuselageconfigura-Of however,theangleofattackatwhichCnQ changessignisincreasedfromabout20.5to24.5.Fortheswetconfigurations(fig.13(b),theredesignedtails. -_ .- - . .- _ _Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IH
34、S-,-,-10 NACATN3551.decreasetheangleofattackatwhichand,aswasnotedearlier,thevaluesof CP forthecompletecotiigurationremainposi-tivearidnearconstantthroughoutthetestangle-of-attackrange(fig.n). Thevaluesof CnP fortheswept-wing-fuselageconfigura-tiondonotbecomepositivefortheangle-of-attackrangetestedex
35、ceptforthesquare-fuselageconfigurationwhichhaspositivevaluesof Cn$fora smallrangeathighanglesofattack.Thevariationof CZB withangleofattackissimilartothatobtainedforthecomplete-confiation,sinceCzB dependsmainlyonthewingcharacteristics.Theeffectoffuselagecrosssectionon CzPissmallforboththesweptandunsw
36、eptconfigurationsinthelowangle-of-attackrangebutbecomessomewhatlargeratthehigheranglesofattack.Aswasnotedforthecompleteconfigurations,Cy becomesveryPlargeatthehigheranglesofattackforthedeep-fuselageconfiguration,andtheeffectsoffuselagecrosssectionon CyP areverylargeattheseanglesofattack.Fuselageandf
37、uselage-tailconfiguration.-Thevariationwithangleofattackof Cy,P CZP,and CnP forthefuselagesisshowninfig-ure19. Dataarepresentedfortwocenter-of-gravitylocations;oneloca-tioncorrespondstothecenter-of-gravitypositionfortheunsweptcon-figurationsandtheothertothecenter-of-gravitypositionusedforthe. . - -
38、_ _ - . -. .-_Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.12 NACATN3551 .sweptconfigurateion.Thefuselagewiththemorerearward center-of-gravityposition(usedwiththesweptconfigurations)isslightlymoreunstabledirectionallythanthatwiththeforwardcenter-
39、of-gravitylocation.Atlowanglesofattack,theshallowfuselage(fuselage4) “isleastunstabledirectionally,whereasthedeepfuselagehasthegreatestdirectionalinstability.Theeffectoffuselagecrosssectionon CnP variesconsiderablywithangleofattack,andalthoughthevaluesof CnB forthesqyareandcircularfusehgearenearlyth
40、esameatlowanglesofattack,thereisa largedifferenceatthehigheranglesofattack.Thesameeffectsareobservedfor Cyp.Atthehighanglesofattack,relativelylargevaluesof CyP areobtainedforthedeepfuselage(fuselage3)aswasthecaseforconfigu-rationswiththedeepfuselagediscussedinprevioussections.Also,ratherhighvaluesof
41、 cYp areobtainedforthesquarefuselage.Forthefuselage-tailconfigurations,Cnp ispositiveinthe lowangle-of-attackrangeforallfuselageconfigurations;however% Premainspositivethroughtheentireangle-of-attackrangetestedonlyforthecircular-fuselageconfiguration.(Seefig.20.) Thedeep-fuselageconfigurationisthele
42、aststableinitially,andthevaluesof% becomenegativeata lowerangleofattackforthisconfigurationthnfortheotherconfigurations.Thisangleofattackisonly4forthesweptconfiguration.Boththesquare-anddeep-fuselageconfigura-tionshavelargenegativevaluesof Cyp athighanglesofattack.Thewing-offinterferenceorsidewashef
43、fectsofthefuselageonthetailcontributionto Cnp areillustratedinfigure21. HerethetailincrementACnP obtainedbysubtractingthevalueof Cnp forthefuse-lagefromthevalueof B ofthefuselage-tailgroupcmibinationisplottedagainstangleofattack.Alsoplottedinfigure21isthe CnBcontributionoftheisolatedtail.Theinterfer
44、enceeffectsuptoan-angleofattackofapproximately10aregenerallysmallandthereislittleeffectofcrosssectionontheinterferenceinthisrange.Atthehigheranglesofattack,cmnparisonofthetail-contributionincre-mentsofthevariousconfigurationswiththeisolated-tailresultsindi-catesthatthecircularfuselagehasbeneficialin
45、terferenceeffectsforbothsweptandunswepttails.Theeffectsofdeviatingfromthecircularcrosssectionareforthemostpartdetrimentalinterference(sideWash)effectswhicharegenerallylargebutvarywithangleofattack.Thesesidewasheffectsaremodified,.ofcourse,whentheh% iSadded.(Seefig.1.2.)Inregardtothetailincrementnjth
46、eresultsobtainedinreference10areofinterest.Thedataofreference10,whichwere,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3551obtainedatanforanunsweptanda negativeThisresultisinthepresentangleofattackof32,showatailtestedona flatfuselage13posit
47、iveincrementof CnPwithmajorsxesverticalincrementfora fkt fuselagewithmajoraxeshorizontal.thesameasthatobtainedatanangleofattackof32investigationforfuselages3and4,respectively(fig.21);however,ascanbeseenfromfigure21,thetailincrementvariesconsiderablywithangleofattack,andatsomeanglesofattacktheresults
48、areoppositethoseobtainedatanangleofattackof32.wing,tail,andwing-tailconfigurations.-ThevariationwithangleofattackOf CYB)CZB)and cnB forthewing,isolated-tail,andwing-tailconfigurationsis”presented”infigure22. Froma studyofthisfig-ureitcanbeconcludedthatthewing,whethersweptorunswept,decreasesthetailcontributionto CnB ofthewing-tailconfigurationatthe“)higheranglesofattack.Fortheunsweptwing,howeve
