REG NACA-TN-3705-1956 An investigation of forward-located fixed spoilers and deflectors as gust alleviators on an unswept-wing model.pdf

1、.fti-., i,:.JFORAERONAUTICSANTECHNICAL NOTE 3705INVESTIGATIONOF FORWARD-LOCATEDFIXEDANDDEFLECTORSAS GUSTALLEVIATORSONANUNSWEPT-WINGMODELByDehNinR. Croom, C. C. Shufflebarger,andJarrettK HLangleyAeronauticalLaboratoryField, Va.SPOIIXRSWashhgtonJw 1956.- . . . . . . . . . . . . . . -.-= =- - -. ., . .

2、 . . . . -e_ -.-.- -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ICGHL16RARYKAFB,NMIlllilfllllllllllllllu*AnNATIONALADVISORYCOM41TTEEFORAERONAUTK!S!mcmmlALNom3705ANINVESTIGATIONOFlKXWU?D-IOCATEDFIXEDSPOIIERSANDIEFLECT6RSAsGUSTMWnWCOWONANUNSWEPT-WI

3、NGMODELByDelwinR.Croom,C.C.Shufflebarger,tivestiga.tionsadJsrrettK.Huffmanwasmadein the LangleyUllLL37q300MPH7-w lo-foottuunelandtheey gusttunneltodeterminethesthowev=,thelift-curveslopeW- nome= fortieWoiler-deflectorcombination.Extendingthedeflectorsnecessitatesonlysmallchangesh attitudeandtriminor

4、dertomatitainagivenltitcoefficient,whereasextendingthespoilerorthespoiler-deflectorccmibinationrequireslargechsnges.Eoththespoilerandthedeflectorcotiigurationsappeartobeeffec-tiveinreductigthenormalaccelerationinbothanupgustandadowngust. Itwouldappearfromthegust-tunnelandwlud-tunneltestsreportedhere

5、inthataforward-locatedfixeddeflectorwouldbeapracticableandeffectivealleviatorofgustloadsonanairplanehawingunsweptwtngswhenturbulenceisencounteredinasmuchas.itreducesthenormalaccel-erations,aidsinslowdowntorough-airspeed,andrequtiesonlysmalltrimchanges.fieliminaryresultsobtainedintheLsngley300MPH7- b

6、y10-foottunnelonamodelhavinga 35sweptbackwzlnghaveindicatedthatdeflec-tors,tohavethesameeffectivenessasreportedfortheunswept-wingmodel,wouldhavetobelocatedmorerearwardonthesweptw- andwouldpossiblyrequhelargerprojections.?J llW!RODUCTION, Oneapproachtogustalleviationinflightthro roughah istoslowdownt

7、owhatiscalledthe“rough-ahspeed,”inasmuchasthemag-nitudeofthenormalaccelerationvariesdirectlywiththeforwardspeed. - - -.- - -. - . . . -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 I?ACATN3705oftheailane.Thenewerhi-speedtransports,whichareaery-na

8、micallycleanerend,ueaver,havealargespreadbetweenthecruisingspeedandtherough-airspeed,reqyireconsiderabletimetoslowdown utotherough-airspeed.(Seeref.1.) Jnasmuchas*emely roughair maybeencounteredduringtheslowdown,itisdesirablefroma structural,andapasseuger-comfortpoiutofviewtoreducethenormalaccelerat

9、ionsduetotheroughairbothduringtheslowdownandaftertherough-afispeedhasbeenreached.Oneofthemanydevicesthathasbeenproposedforuseinreducingtheacclerationeffectsofrough- isthespoiler.E thespoilerislocatedneerthewingleadingedge,itshouldbecapableofreducingtheaccelerationbecauseofthereductioninMft-curveslop

10、e.Thislossinlift-curveslopeisassociatedwiththeinsensitivityoftheseparatedregionreerwardofthespoilertochsmgeinangleofattack.Thisassumptionhasbeenverifiedbyinspectionofthepressure-distributiondataavailableforspoilersonunsweptwings.E thespoilerislocatedoutboardonthewing,itshouldreducethewingrootbending

11、momentbyshiftingthecenterofloadtibosrd.Inaddition,spoilershavebeenshowntobepowerfulspeedbrskes(ref.2)andshould -beusefulinslowlngdowntorough-airspeedsandinrapiddescents.Anevaluationofafixedspoilerasameansofreducingthenormal .accelerationduetoagustwaamadeintheIangleygusttunnelandisreportedinreference

12、3. Onlyonespoikrconfiguration,whichhadasmalll.projection,wastested.Thespoilerinvestigatedextendedalong90percentofthewingspa,waslocatedalongthe12-percent-chordline,andprojetted2.5percentchord.Theresultspresentedinrefer-ence3indicatethatthereductioninU.ft-curvesloperealizedforaforward-locatedfixedspoi

13、lerreducedthemaximumaccelerationbyabuut30percentinarepresentativegustofll?-chordgradientU.stance.However,therewaanoreductioninmsximmaccelerationinanonrepre-sentativesharp-edgegust.Theineffectivenessinthesharp-edgegustprobablyresultedeitherfromalargelagineffactivenessassociatedwithfarwsrd-locatedspoi

14、lers(refs.3and4)orfromthenonlinearlift-curveslopesassociatedwithspoilersofsmallprojectionlocatedwellforwardonthewing.Thepresentpaperreevaluatestheproblembyusingspoilersofsufficientprojection(7.5percentchord)toassureanear-linearltl?t-curveslopeandbyusinglower-sacespoilers(hereinafterreferredtoasdefle

15、ctors).Thedeflectorsexhibitaboutthesamereductioninlift-curveslopeasthespoilersbut,asshowninreference4,shouldhavesmalllag.TheinvestigationhasbeenconductedtitieLa300MPH7-by10-foottunnelsndtheLangleygusttunnelona simulated otranspwtaWplanemodeltodeterndnetheaerodynamiccharacteristics minpitchandthegust

16、-alleviationcapabilitiesoftheforward-locatedfixedspoilersenddeflectors.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3705 3.-coEE!FIEIEr?TsANDSYMmLSTheresultsofthetestsarepresentedasstandardcoefficientsoffcmcesandmomentsaboutthewindaxes.CD4CL

17、%1A%f%l,maxbcF$%rssuaxagCoefficient, =(jet-boundarycotion appliedtodragcoefficientlift. Coefficient,=qspitcg-t cOefficient,referredto0.25F,PitchinEmomentaccelerationincrementduetogust,gunitsmaximumaccelerationincrementduetogust,gunits* span,5.96ftwtflglocalchord,ftwingmeanaerc chord,0.69ftaccelerati

18、onduetogravi,ft/sec2horizontal-tailincidence,positivewhentiai13ngedgedeflecteddownward,deg-c presswe, lb/sqftfuselageradius,in.wingax=,3.73Sqftdistancepenetratedtntogustbyleadingedgeofwingmeanaerodynamicchord,.chordsgustveloci,ft/sec. - - - -. . . - .- . - -Provided by IHSNot for ResaleNo reproducti

19、on or networking permitted without license from IHS-,-,-4 Ihowever,allspoiler ,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.,.NACATN3705 7anddeflectorconfigurationsincreasedthedragcoefficientconsiderably,especiallythespoilerandspoiler-deflectorc

20、ombinatia.Ataliftcoef-ficientof0.38,theratiooflifttodragforthebasicmodelwasapprox-imately16,forthedeflectorconfigurations,aximately6j andforthespoilerconfiguration,approximately2;therefore,anyofthedeviceswouldbeeffectiveasanaerodynamicbrake. .RelimhsryresultsobtainedintheLangley300MPH7-by10-foottunn

21、elindicatethatdeflectacs,tohavethesameeffectivenessona35sweptbackdng asontheun.swconsequently,therecordswerefairedasshown figure6 to obtainthevariationsofaccelerationwithdistancetraveled.Theseoscillationswerenotpresentinthepitchhistories.Forallconfigurationstested,aminimumoffivesuccessfulflightswasm

22、adeandtheresultsoftheseflightswereaveraged.Theaveragecorrectedandfairedvaluesofthenormal-accelerationincrementandthepitch-angleincrementasafunctionofgustpenetrationarepresentedinfigures7 to9.A comparisonofthevaluesoftheestimtedmaximumaccelerations(determhedfromeq.(2)ofref.6 by usingtheexTertientaI.l

23、ift-curveslope)andmeasuredmaximumaccelerationsisgiveninfigure10. Theacceleraticmhistories(fig.7) - themsximumaccelerationincrements(fig.10)indicatethatboththe1/2-and2/3-spandeflectorconfigura-tionswereeffectiveh reducingthemaximumnormal-accelerationincre-mentinthesharp-edgegustbyaoximately20to40perc

24、ent.Thisreductionisingoodagrementwiththeexpectedreductionb normal-accelerationticrementbasedcmthereductioninlift-curveslope(fig.4). Inspectionofthepitch-anglehistories(fig.7) indicatesalsothat,althoughthepitchhgactioninthegustwaschangedbytheadditionofthedeflector,thechaugesweresmall.- - . .- . -Prov

25、ided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 NACATN3705Theaccelerationhistories(fig.8)togetherwiththecomparisonbetweencalculatedandexperimentaldata(fig.10)indicatethatboththespoilerandthespoiler-cleflectorconibinationwereeffectiveinreducingthenormal

26、-accelerationincrementh e sharp-edgegust.Theflightsmadeataforwardspehowever,thepitcheffectsarestilll.relativelysmaU,atleastuntilmaximumaccelerationisreached.Althoughtheresultsinfigures7to9areforasharp-edgegust,theeffactivenessofthecontrolinothergustscsnbeestimated.Theeffactivenessofthecontrolsingust

27、swithgradientdistancesupto20chordsisfairlyevidentinasmuchastimehistoriesforthewingwithcontrolsshowapproxtitelyaconstantpercentagereductionforallpenetrationsuptothelimitofthetests.lhasmuchasthisreductionsmountstoanoverallreductioninresponsefarallinputsupto20chords,superpositiontheorywouldyield.thessm

28、ereductionbothfor 1gustswithgradientdistancesupto20chordsandforsharp-edgegusts.Becauseboththespoileranddeflectorconfigurationsappeareffec-tiveinsnupgust,itmightbeexpectedthatthecontiolswouldalsobeeffectiveinadowngust.lhasmuchasexitfromthesharp-edgegustcorrespondstoentrytntoadowngust,afewflightswerem

29、adewiththe2/3-spandeflectorconfigurationanddatawererecorded.forsomedistanceafterexitfromthegustprofileshowninfigure3. Thesedataarepresentedinfigure11. Byaddingtheaccelerationandpitch-angleincrementsatgustentrytothetimehistoryatgustexit,thetimehistoryforacontinuousshsrp-edgegustwasconstructedasshownb

30、ythedashedlineinfigure11.Althoughtheresultsareonlyapproxhuate,theyindicatethatsubstantiallythessmealleviationcouldbeectedforadowngustasforanupgust.Theresultsfromtheflightsofthemodelthroughsharp-edgegustsindicatethat,fortheconditionsofthetests,theeffectivenessofeitherthespoilerorthedeflectorwasnotapp

31、reciablyaffectedbylag.Thisfactmaymeanthatthelagh effectivenessofa spoilerasobtainedfromabruptdeflections(ref.4)maynotberepresentativeofthelagassociatedwithanabruptchangeinangleofattackoftheMng withspoilerdeflected.Becausethebasicmodelrequires8chordlengthstoobtainmaximumacceleration,itisnotpossiblefr

32、omthesetestresultstoevaluatecompletelytheeffectsofspoilerlag.Additionalinforma-tionontheeffectofsuddenangle-of-attackchsngesonwtngswithfixed -spoflersmustbeobtainedbeforeanydef%itestatementaanbemaderegardingtheeffectofspoilerlagontheresponseofsnalsneenteringasharp-edgegust.Itwouldappesr,however,that

33、aWplsnes .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-9.NACATN3705withresponseinvestigationlocatedfixedcharacteristicssfmilartothose ofthemcdelusedinthiswouldgivesatisfactorygustalleviationwithaforward-spoiler.II?thespoilerIsplannedtobeusedwherer

34、apidcontrolresponseisrequired,thelagrestitspresentedinreferencekwouldindicatethatthespoilerwouldrequireasmuchas8chordlengthsafterdeflectionbeforefulleffectiveness%muldberealized;however,thedeflectorwouldobtainfull#festivenessinapproximately1chordlength.Short-Periodlh?equencyad DsmpingForcontinuoustu

35、rbulence,theeffectofanycontrolontheshort-periodfrequencyanddampingmsybeimportantandareductionh fre-quencyordampingmsybeexpectedtoincreasetheloadsingusts.Cal-culationsforthebasicmodelandthe2/3-spsndeflectorconfigurationindicatednosubstantialchangeintheperiod(frequencyofmotion)duetoadd+ngthecontrolont

36、hetestmodelandshowedthatthecontrolreducedthedamping(timetodamptoone-halfamplitude)from8.4chordsforthebasicmodelconfigurationto9 chordsforthe2/3-spandeflectorconfiguration.!Ihisreductionindicatesonlyaveryslightdecreaseh-ing andthealleviationofgustsasobtainedfromgust-tunneltestresultsisabouttheallevia

37、tionthatwouldbeexpectedinflight.CONCLUDINGREMARWResultshavebeenpresentedofanWrestigationintheLangley300MPH7- by10-foottunuelandtheLangleygusttunneltodeterndnetheeffectivenessoffixedspoilersanddeflectorsatthe12-percent-chordlineasgustalleviatorsonasixmil.atddtransportairplanemodelhavinganunsweptwinga

38、71Thelift-curveslopesforthiscohowever,useofthespoileranddeflector“incombinationcausednonlinearitiesinthelift-curveslape.Extendingthedeflectorsregyiredonlysmallchangesinattitudeandtrimformaintenanceeofagivenliftcoefficient,whereasextend-thespoilerorspoiler-deflectorcombinationrend largechanges.Theseg

39、ust-andwtnd-tunnelstudiestiicatethataftieddeflectorplacedneartheleadhgedgeofanunsweptwingwouldbeapracticableandeffectivealleviatorofgustloadswhenturbulenceisencounteredinasmuchasitreducesthenormalaccelerations,aidsh slowdowntorough-airspeed,andregyiresonlysmalltrimchanges. . . . - -.- .-. . - .c - -

40、 - - . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACA 3705.Resultsofalimitedstudyofdeflectorsasgustalleviatorsona35sweptback-wingmcdelintheLangley300MPH7-by 10-foottunnelindicatethat,inordertoobtainthessmeeffectivenessasobtained .withthewep

41、t , thedeflectorwouldhavetobelocatedmorerear-wsa?dfromthelead edgeandwouldpossiblyrequirelargerprojections.LsngleYAeronauticalLaboratoryNationalAdvisoryCommitteeforAeronautics,LangleylHeld,Pa.,Msxch15,1956.IummNcEs1.Davis,DonD.,Jr.:!l?heInb 2NACATN3705.q(e)Cmibinationl/2-spnspoileranddeflectorconfig

42、uration.Figure4.-Concluded.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3705cm0, deg19if, oega75 z Basicmodel02 V = * feet per second.E?=, # 8Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-t

43、-4 o 4 8 /2 /6 20 24s#Chods(a) U f=I-Ofeet per second;V = 99 feet p3r second.Figure 7.- Variation of incrementalpitch angle and nd accelerationwith gust penetration forthe deflector configurations. ivPProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-A

44、 OGV = 98 feetFQure 70- Condd.per second.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-, . .IIFigureforperAt9,degAun,g unitsSpoiter spun Defhti sponY Y* Jj zM x W2off off1 - 0.5/ 0.98 0.5/ 0.98. 3/ .98 off:4 0 4“8 /2 /6 20 “#S,cho?vk8.- Variation M

45、 incrementalpitch angle and normal accelerationwith gustthe epoilerand spoiler-deflectorconfigurations. U E u feet per second;second.penetrationv.98 feetsIProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Spoiler spanI*At9 Odeg-/2Aon, ,g unitsY*IFigure

46、9.- Variationof incrementalpitchthe 2/3-spanspoiler configuration.1 n8 /2 /6 20 24s,chordsangleandnormalaccelerationwithgustpenetrationforU=10feetpersecond;V =120feetpersecond.1Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-G NACATN37051.25Estimated

47、-. AOn,max8g units “40 0Figure10.-Variationnormal.Spoiler spun Mlecfor spunoff 0.5/ Q98off .31 .98A C?3/ 0.98.5/ .98 off.5/ .984 8 /2 16U,ft/secoftheestimatedandmeasuredmaximumaccelerationswithgustvelocity. incremental - . .- -. . .-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-84A8, ./dllg-2-3/Aun,g.units4 o 4 8Figure IL.- Variation of incremmtal pitch angle andfor the 2/3-sptuIdeflectorconfiguration. U . 15“/2Sfichrds Flanormsl acceleratIon with gust penetratIonfeet per second;V . * feet per second. 3,Provided by IHSN