1、cm ( -)FOR AERONAUTICS L_TECHNICAL NOTE 2175EFFECT OF AN UNSWEPT WING ON THE CONTRIBUTION OFUNSWEPT-TAIL CONFIGURAllXONS TO THE LOW-SPEEDSTATIC- AND ROLLING-STABILITY DERIVATIVESOF A MIDWING AIRPIJA?N3 MODELBy William Letko and Donald R. 131eyLangley Aeronautical LaboratoryLangley Air Force Base, Va
2、.Washington!I11,I1II1I,i-.1-, . . . . - - - -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NM. lplllllulllllllQlOll011b5J73NATIONALADVISORYCOMMITTEEFORAERONAIJTMJOTECHNICALNOTE2175EFFECTOF AN UNSWEPTWINGON THEUNSWEPT-TAILCONFIGURATI
3、ONSTOSTATIC-ANDROLLINGSTABILITYOF A MIDWINGAIRPLANECONTRIBUTIONOFTHELOW-SPEEDDERIVATIVESMODEL WilliamLetkoandDonaldR. Riley ,SUMMARY .An investigationhas beenconductedin theLangleystabilitytunnelto detemine the effectof an unsweptwingon the contributionof unswept-tailconfigurationsto thelow-speedsta
4、tic-androUing-stabilityderiva-tivesof a midwingairplanemodel.Theresultsof the investigationshowthat,at anglesof attacksllmostto the angleof maximumlift,thereare onlysmalldifferencesinthetailcontributionsto thestatic-lateral-stabilityderivativesforconfigurationswithwingon andwithwingoff. Forthisrange
5、of anglesof attackthe contributionsof theverticaltailcanbe estimatedfair3yaccuratelyby theavailableprocedures;Theavsilableproceduresgenerallypredictthewing-offvaluesoftherollingderivativ%at lowanglesof attackwithreasonableaccuracy.Alteringtheseequationsto accountfor sidewashcausedby theunsym-metrica
6、lwingload (dueto roll)bringsthe calculatedwing-onvaluesintomuchbetteragreementwiththemeasuredwing-onvalues.Someerrorin theestimatedcontributionof thetsi.1to theyawingmomentcausedby rollresultsfor the low-horizontal-tailconfigurationbecauseof a forwardshiftin the centerof pressureof thevertical.tsilc
7、aused thehorizontaltail. .INTRODUCTIONRecentadvancesin theunderstandingof theprinciplesof high-speedflighthaveledto significantchangesin”thedesignof componentpartsof airplanes.Inmanyinstancesconsiderationis givento coilfigurations. . . . . . . . . . -_ - .- . .-. . -.- . _ .-. .- _.Provided by IHSNo
8、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-r2 NACATN 2175whichsrebeyondthe rangecoveredby”availabledesigninformationregardingstabilitycharacteristics.Theeffectsof changesin wingdesignon stabilitycharacteristicshavebeenextensivelyinvestigated.ti orderto providein
9、formationon theinfluenceof otherpartsof thecompleteairplane,an investigationof a modelhavingvariousinter-changeablepartsis beingconductedin theLangleystabilitytunnel.Reference1 presentstheresultsof an investigationon theeffectofhorizontal-taillocationon the low-speedstaticlateralstabilitycharacteris
10、ticsof a modelhaving45 sweptbackwingandtailsurfaces.As partof thisgeneralinvestigation,the effectof an unsweptwingon the contributionof an unsweptverticaltail.to the staticlateralandroll stabilitycharacmristicshasbeendetermined,andtheresultsarepresentedherein. Theseresultsservethepurposeofcheckingth
11、evalidityof presentmethodsof estimatingthecontributionsof componentpartsof airplaneswhenappliedto representativecurrenthigh-speedairplanedesigns.SYMBOLSThe datapresentedhereinarein theformof standardNACAcoef-ficientsofforcesandmomentswticharereferredto the stabilitysystemof axeswiththe origincoincid
12、ingwiththewingaerodynamiccenter. Thepositivedirectionsof theforces,moments,andangulardisplacementsare shownin figure1. The coefficientsandsymbolsaredefinedas follows:CL . liftcoefficient(L/qSW)Cx longitudinal-forcecoefficient(x/w) -% lateral-forcecoefficient(Y/qSJC2 rolling-momentcoefficient(L/qb)cm
13、 pitching-momentcoefficient“(M/qSCn yawing-momentcoefficient(N/qSWb)L liftx longitudinalforce (-Dragat $= 0)Y lateralfQrce,._. -. - - . . -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 2175.r,LIMNq%7bAcF .h-%2a?$DvProllingmomentpitchingmomen
14、tyawingmomentdynamicpressurewingareavertical-tailareawingspanaspectratiowingchordwingmeanaerodynamicchordverticaldistanceaboveor belowtunnelcenterlineperpendiculardistancefromfusel?gecenterpressureof verticaltailtaillength;distance,parallelto fuselagewingmountingpointto centerof pressurelineto cente
15、rofcenterline,from ofverticaltailangleofangleofplane,angleofsidewashattackof wingor fuselagecenterlineattackofverticaltailmeasuredin a horizontalpositivewhenit resultsin a positivelateralforceyawangleat verticaltail;the changein angleof attackof a sectionof verticaltail resultingfromadditionofawingt
16、o fuselageandvertical-tailcombinationoperatinginrollingcondition,positivewhenit resultsin a positivelateralforcefree-streamvelocityrollingangularvelocity. - . - - - - - .- . . - - -. .-7 _ -, . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. - .-.
17、- ._.-rateof changeofhelixangle-.rateof changeoftiphelixanglevertical-tailINACATN 2175 -.angleof attackwithwing-tip usidewashangleatverticaltailwithwing-pbE wing-tiphelixangleCL= lift-curveslopeof wingCL lift-curveslopeof verticaltail (CL of verticaltailbased% on vertical-tailarea) #acy% =$ alfZICnc
18、%=2VaczCz =P *2V.uD. . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 2175APPARATUSANDMODELS!5.Thetestsweremadein the 6-foot-diametertestsectionof theLsngleystabilitytunnel. Thissectionisequippedwitha m6tor-drivenrotorwhicharts a twistto the
19、air streamso thata modelmountedrigidlyin the-tunnelis in a fieldof flowsimilarto thatwhichexistsaboutan airplanein roJ. . . . . . . . . . . . . . .Area,squareinches . . . . . . . . . . . . . . . . . .Span,inches. . . . . . . . . . . . . . . . . . . . . . .Meanaerodynamicchord,inches. . . . . . . . .
20、 . . . . .Taillengthjinches . . . . . . . . . . . . . . . . . . . . g.:. . . “o. . 0. . 0k6A6A00;. . 324. . 36. . 9.19. . 2.0. . 0.6tiA 65A0. . 48.60.0 9.86. . 5.03. . 15.38. . ._. . . . . - . - - - - -. - - . - - .- ._. ._._.-. . . _ .Provided by IHSNot for ResaleNo reproduction or networking permi
21、tted without license from IHS-,-,-6.NACATN 2175Horizontaltail:Aspectratio. . . . . . . . . . .Taperratio . . . . . . . . . . .Qusrter-chordsweepangle,degreesIncidence,degrees . . . . . . .Dihedrslangle,degrees . . . . .Twist,degree s . .Airfoilsection . . . . . . . . .Area,squsreinches . . . . . . .
22、Span,inches. . . . . . . . . .Meanaerodynamicchord,inches. . . . . . . . . . . . . . . 4.0. . . . . . . . . . . . . . 0.6. . . . . . . . . . . . a71 . o. . . . . . . . . . . . . . 0. .0. . . . . . . . . 0. .0. . . . . . . . . . . . . . . . . . . NACA65AOO;a71 . . . . . . . . . . . . . 64.80. . . . .
23、 . . . .* . . 16.10. . . . . . . .0. a71 . 4.11Detailsof thevcbg,fuselage,andtailsurfacesandtherelativeloca-,tionsof thewingandtsilswithrespectto thefuselagearegivenin a71figure2. A photographof oneofthe configurationsmountedin thetunnelis givenas figure3.Thetestconfigurationsanddesignationsusedin i
24、dentifyingthedatain the figuresaregivenin thefoowing table:wing . . . . . . . . . . . . . . .*.Fuselage; : . . . . . . . . . . . . . . . . . . . . .Fuselagewithverticaltail. . . . . . . . . . . . . .Fuselagewithverticaltailandlowhorizontaltail . .Fuselagewithverticaltailandhighhorizontaltail .Wingwi
25、thfuselage. . . . . . . . . . . . . . . . . .Wingwithfuselagesndverticaltail . . . . . . . . .Wingwithfuselage,verticaltail,andlowhorizontaltail . . . . . . . . . . . . . . .Wingwithfuselage,verticaltail,andhighhorizontaltail . . . . . . . . . . . . . .*. * w. . . . F,*. F+V. . F+ V+HL. . F+ V+HH. .
26、 W+F. . W+F+VW+ F+ V+HLW+ F+ V+HH,Fortheteststhemodelwasmountedon a singlestrutsupportatthequarter-chordpointof thewingwhichcoincidedwiththego-percentpointofthefusel-elength(fig.2). Forcesandmomentsby meansof a conventionalsix-componentbalancesystem.TESTS .wereasuredTestsweremadeat a dynamicpressure
27、of 39.8poundsper squarefoot,whichcorrespondsto a Machnumberof about0.166anda Reynoldsnumberof 8.8x 105basedon themsanaerodynamicchordof thewing.Themodelwas testedthroughan angle-of-attackrsngefromabout-h”up to andbeyondthe angleoflift at anglesofyaw of Oo ando-. . _ _ _._ . .-.Provided by IHSNot for
28、 ResaleNo reproduction or networking permitted without license from IHS-,-,-sa71 NACATN 2175 7-. in straightflowandat an angleofyaw of 0 in rollingflow. Forthestraight-flowtestsat 0 angleofyaw,lift,drag,andpitchingmomentsarepresented.Dataobtsinedin straightflowat *SOyaw andin rollingflowat severalva
29、luesof pb/2V wereusedto obtainderivativesoflateralforce,yawingmoment,androllingmomentwithrespectto yawangleandwing-tiphe15xangle. The testvaluesof pb/2Vwere+0.0206,*0.ll, and*O.0616. Alsoforthesevaluesof pb/2V sidewashanglesin theplaneof symmetg behindtheisolatedwingweredeterminedbymeansof a yaw tub
30、e. The sidewashmeasurementsweremadeat O, 3, 6,and 9 inchesverticallyaboveandbelowthetunnelcenterline. Themeasurementsweremadeat twolongitudinalpositions;onewas 1.28 feet(Zv= 0!I27)behindthewing-mountingpoint(correspondingto thelongi-Ttudinalpositionof the centerof pressureoftheverticaltailat zeroang
31、leof attackof themodel)andthe otherwas at abouttwicethat(Zv )distanceor 2.56feet = 0.854. For thepositionl.28feetbehind.thewing-mountingpoin,”measuremhowever, %nisprimarilya functionof thewingcharacteristics. .Somedifferencesin the static-lateral-andin therolling-stabilityderivativeshavebeenobtained
32、forthetwotailconfigurations,wingonandwingoff,which.willbe discussedsubsequentlyin the sectionontailcontribution. ,WingCharacteristicsThe lift,longitudinal-force,andpitching-momentdataof thewingalone(fig.h(a)showno unusualcharacteristics.The experimentallift-curveslopeis 0.0630,whichcompareswell.with
33、thetheoreticalvalueof 0.0642givenin reference3. At lowanglesof attackthe aero-dynamiccenterof thewingis locatedat about21.8percentof themeanaerodynamicchordas comparedwiththetheoreticallocationwhichisgivenin reference3 as 25 percentof thewingmeanaerodynamicchord.The static-stabilityderivativesof the
34、wingareplotted-againstliftcoefficientin figure7 andsrecomparedwithvaluescslculatedthemethodsof reference4.agreementwiththemeasuredThevaluesof thewingcoefficientin figure8 andIn general,the calculationsarein goodvaluesexceptathighliftcoefficients.rollingderivativesareplottedagainstliftare comp=ed wit
35、hcalculatedvalues. The.-. .-. _ ._. _ _ _ _ ._. _ , - . -+. -.,“Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACATN 2175valuesof CnD calculatedby themethodof referenceS agreeverywellwiththemeahowever,therateof increasewithliftcoef-ficientis som
36、ewhatlessthantheempiricslresultfoundin reference,Figure9 of reference5 indicatesthat Cy CL is proportionalto l/AP/for unsweptwings. wFuselageCharacteristicsAlthoughthefuselagecontributessomewhatto mostof the aerody-namicforcesandmoments,themost importanteffectson the aerodynamiccharacteristicsof the
37、 airplanesrecausedby the contributionof thefuselageto the staticlongitudinalanddirectionalstability.Thefuselagecontributesan unstablemomentbothin pitchandyaw. As canbe seenfromfigureh(b),the instabilityh pitchdecreasesastheangleof attackis increased,whereasthe instabilityinyaw,measuredat smsllangles
38、ofyaw,remainspracticallyconstantthroughouttheangle-of-attackrange(fig.(b). The instabilityof thisfuselageisverynearlythe sameas thatofthefuselagereportedon in reference1,withthe exceptionthatthefuselageofreference1 ismore unstablein ,tpitchat highanglesof attack. (Thefuselagessreof the samelength,ar
39、eidenticalsheadof themidpoint,snddifferonlyin the shapeof thetsilcone. Thefuselageof reference1 is symmetricalaboutitsmidpoint.) “ . . _ . -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN 217S 1-1. Theblunt-tailconeof thefuselagestabilityathig
40、hpresentfuselageappearsto increasetheanglesof attack.,InterferenceIncrements Whenthewingandfuselageare combinedthe effectsofmutualinterferenceon the contributionof eachto the stabilityderivativesandthe contributionof thesecomponentsto theflowangularityat the ,tailarealsoto be considered.Themutualint
41、erferenceeffects,ordinarily,areratherdifficultto evaluateandareusuallyneglectedexceptwhentestresultsareavailablefQr a modelwhichcloselyresemblestheairplaneunderconsideration.In thisevent,recourse.is madeto a method(analogousto previouswork,suchas reference7,for estimatingthe staticlateral-stabilityd
42、erivativesof a completemodel)whichmakesuse of interferenceincrements.TheseincrementsaredesignatedAl and A2 andtheequationfor estimatingthe deriva-tivefor a completeairplaneis illustratedbelowin termsof CnV,for-le : .Cn$=cwfF+%W+lchf+%v+H+ZcwThe incrementAl is the changein the derivativecaused mutusl
43、interferenceof thewingandfuselageandcanbe obtainedfromtestresultsfollowingequation:forthemodelwithoutthetailin themannerillustratedby theThisincrementwas determinedfor the testconfigurationsandis shownin figures9 snd10 for the static-stabilityand-rolling-stabilityderivatives,respectively.The interfe
44、renceincrement Al of boththestatic-androlling-stabilityderivativesis generallysmallforthepresenttestsexceptat anglesof attacknearthe stall. For a.high-wingor a low=wingconfigurationthisincrementwouldprobablybe some-whatlsrgerevenat smallanglesof attack.Theincrement A2 is directlyconcernedwiththetail
45、contributionandis the changein effectivenessof thetailcausedby additionof thewingto the fuselage- tail-groupconfiguration.The terferenceeffectsof thefuselageon thetailgrouparenot determined.The increment A2.is obtainedfromthetestdataas shown,.for example,by thefollowingequationfor A2Cn:* . - . . .-.
46、 - . - . - -.- - .- - - - - . -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.12,NACATN 2175“%= (%.+,+,+,- %fW+.)- (c%,+.+.- C“If,)Thisincrementis combinedwiththe estimatedACn%+Hto givethetotalestimatedtailcontribution.It shouldbe remembered,howeve
47、r,thattheincrement A2 canbe usedto determinetailcontributionsforan airplaneonlywhenit is obtsinedfromtestsof a modelwhictlcloselyresemblesthe airplaneunderconsideration.TheincremetitsA2 of the staticlateral-stabilityandrolling-stabilityderivativesofthe testconfigurationsareshownin figures11 and12,re
48、spectively.Thesefiguresshowthatthevaluesof the ticrement A.2 of the staticlateral-stabilityderivativesareverynearlyzerofor lowandmoderateanglesof attack,whereastheticrementsof the rolling-stabilityderivativesarerelativelylargeevenat smsllanglesof attack. Sincethe incre-ment A2 dependslargelyon theresultantof the sidewashcauseduns
