FORAERONAUTICS

TECHNICALNOTE3062

A F12GHTINVESTIGATIONOF THEPRACTICAL

PROBIIIIMSASSOCIATEDWITHPOROUS-

LEADING-EDGESUCTION

ByPaulA..HunterandHaroldL Johnson

LangleyAeronauticalLaboratoryLangleyField,Va

~

WasMngt.on

February1954

.-.2~.

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https://ntrs.nasa.gov/search.jsp?R=19780078540 2018-05-22T13:14:47+00:00Z

TECHLIBRARYKAFB,NM

lx

.NKTIONALADVISORYCOMMITTEEFORAERONAUTIC.

.

IIOLL274

TECHNICALNOTE3062

A FIZGHTINVESTIGATIONOFTHEPRACTICAL

PROBIIMSASSOCIATEDWITHPOROUS-

IWDING-EDGESUC?TION

By PaulA. HunterandHaroldI.Johnson

SLIMMARY

A flightinvestigationhasbee~made.oftheyracticalproblemsassociatedwiththeuseofporous-leading-edgesuetion. Thewingleadingedgeofthetestairplanewasporousoverapproximately83 per-centofthespansndthefirst8 percentofthecholdontheuppersurface.VWiousotherextentsofsuctionareawithintheselimitswerealsotested.

Resultsofthisinvestigationhaveindicatedthata wingequippedwithporous-leading-edgesuctioncanle constructedwhichhassufficientstrengthanddurabilityforusein flightwithoutaddingexcessiveweight.Forthetypeofporousmaterialusedinthisinvestigation,cloggingdueto atmosphericdustdidnotappearto%e a problem.Forthelightrainencounteredinflight,thePOWEYrequiredto producea givenflowcoef-ficientwasabout50 percent.nmrethanthatrequiredforthedrycondi-tion. Basedonthegrounddata,itwasestimatedthatforflightinheavyrainthepowerwouldbe approximatelytwicethatforthedrycondi-tion. Atmaximum%lowerspeedtheporousareabecsmeclesredwithin3 to 4 minutesafterwaterceasedto impingeonthesurface.Undercertainconditions,testsshoweda severevibratjonoftheporousmate-rialinducedby an “organpipe”resonanceoftheaircolumuwithintheducts. As expectedfromwl.nd-tunnelresultsobtainedprevioustothisinvestigation,theuseof leading-edgesuctionwiththesmallamoumtofpoweravailablehadlittleeffectonthemaximumliftcoefficientdevel-opedwiththeairfoilsectionusedinthiswing(MICA2412).Ingeneral,an appreciabledropoccurredinmaximumliftcoefficientfromtheleading-edge-sealedconfi~ationto theconditionof zerosuctionwiththeporous-areaconfigurationstested.Incrementsin liftcoefficientduetothesuctionavailablegenerallybroughtthemaximumliftcoefficientbackapproximatelyto thevalueforthewingwiththeleadingedgesealed.Themaximumtheoreticalaerodynamicpower,ifductlossesareexcluded,variedwiththeconfigurationstestedfrom3.65 to 9.70 horsepower.

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2 NACATN 3062

INTliODUCTION

Theuseofporoussurfacesforboundary-layercontrolhasforaperiodofapproximately30 yearsbeenthesubjectofmanytheoreticalandexperimentalstudiesinvolvingareasuction.Previousflightstudiesof sreasuctionhavebeenlimitedmostlytomodelssndpartial-spantestsections(forexample,refs.1 and2),althoughan incompleteinvestiga-tionofsreasuctionappliedtonearlyalltheresrwardportionsoftheuppersurfaceofthewtngsofan airphe wasqadeinEnglandnearthebeginningofWorldWarII (ref.3). In thepresentinvestigation,porous-leading-edgesreasuctioncoveringthefirst8 percentchordontheuppersurfacewasappliedto essentiallytheentirewingspanoftheairplanetested.

Theuseofareasuctioninvolvesseveralpracticalproblemswhicharenotreadilysolvablebywind-tunnelstudies.Oneofthegeneralproblemsisthecloggingoftheporesofthemoredensematerialsby atmw-phericdustandby rain. Constructionofa structurallyefficientwingwithporoussurfacesisanotherpracticalproblemwhich,thoughimportant,doesnotappeartobe extremelydifficult,particularlyinthedesignofa newwingwheretheductingcanhe madepartof theload-carryingstructure.

TheNationalAdvisoryCcmmitteeforAeronauticshasconductedaflight-testpro-to investigatevariouspracticalproblemsassociatedwiththeuseofporousmaterialsforboundary-layercontrol.Becausetheairplaneavailableforthetestshada rounded-leading-edgetypeofair-foil(NACA2412)characterizedby a trailing-edgestall,verylittlebenefitinmsximumliftcouldbe expectedfromtheapplicationof lead.ing-edgesuction.Thisexpectationwasverifiedby two-dimensionalwind-tunneltestsmadepriorto theflightinvestigation.

SYMBOLS

b s-pan,ft

c localchord,ft

CL airplaneliftcoefficient,-lL(ncosa+Zsj.na)~cSA

‘

.— ———— —-—— .

NACATN 3062 2

CQ

Ho

%

H1

2

n

P

PO

pd

PI

AP

Q

q

qc

%

ql

s

SA

s;

‘P

d

suctionflowcoefficient(aconstantvalueof S~ correspondtigto 89.2percentoftotalwingareawasusedincomputingflow

coefficients),-Qvs~

free-streamtotalpressure,% +Po, lb/sqft

ducttotalpressure,p~ + qd,lb/sqft

ducttotalpressureat outboardmeasuringstation,lb/sqft(assumedH1 = PI; ql = O)

longitudinalacceleration,~sitiveforward,g units

normalacceleration,positiveupward,g units

staticpressureatwingsurface,lb/sqft

free-streamstaticpressure,lb/sqft

ductstaticpressureat inboardmeasuringstation,lb/sqft

ductstaticpressureatoutboardmeasuringstation,lb/sqft

pressuredifferenceacrossporousmaterial,lb/sqft

totalvolumeflowrate,cu ft/sec

impactpressureatwingsurface,lb/sqft

calibratedimpactpressure,lb/sqft

ductimpactpressureatinboardmeasuringstation,lb/sqf%

ductimpactpressureatoutboardmeasuringstation,lb/sqft

pressurecoefficient,HO-P q=—qc %

wingarea,sqft

wingareaaffectedby suction(sreabetweenspanwisestationsatouterextentsofporousarea)

areaofporous~terialmeasuredalongsurface,sqft

.

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4 mc~TN3062

v trueairspeed,ft/sec

v apparentvelocitythroughporousmaterial,~, ft/sec%

w airplaneweight,lb

x chordwisedistance,ft

Y spanwisedistance,ft

z distancenormalto sirfoilchord,ft

a calibratedangleof attackreferredto thrustsxis,deg

APPARATUS

Airplane

FlighttestswereconductedontheCessna190airplane(seetableIfordimensionaldsta)showninthephotographs”presentedasfiguresl(a)andl(b)andinthethree-viewdrawinginfigurel(c).Therelativesizeandlocationofthelower-surfacesplit-typeflapareshowninfigure1(c).Figurel(d)showsa comparisonoftheactualwingprofileat a representa-tivespanwisestationwiththeNACA2412profileandalsosomedetailsoftheporous-leading-edgeconstructiontobe describedsubsequently.TheactualwingprofilediffersfromtheNACA2412profileinthatithasaslightlylargerleading-edgeradius,haslesscamberinthefirst10per-centofthechord,andhas& slightamountofnegativecamberinthefirst2 percentof thechord.Thesevariationsresultedfrommanufac-turingandmodification-shoptolerances.

-Boundsry-Layer-ControlEquipment

Theporoussurfaceconsistedof a sandwichcontaininganoutersur-faceofwovenMmel filtercloth,a 16-meshcopperwindow-screensepa-rator,anda backingof0.016-inch-thickperforatedbrasssheet.ThefilterclothwaswoveninDutchweavewith30wiresby 250wiresperinchto a thicknessof0.028inch,rolledto0.020inch,andfurtherhamneredto 0.018inchto reducetheporosityandimprovethesurfacesmoothness.ThefilterclothwasobtainedfromtheMichigsnWireClothCompany.Theperforatedbrass,whichwasusedto stiffenthefiltercloth,had714openingsof0.020-inchdiameterpersquareinchspaced0.041inchapart. . .Thesandwichwasformedto theleading-edgecurvatureon steeljigsandthethreelayerscementedtogetherwitha plasticadhesiveattheedgesonly. u

NACATN 3062 5

Wind-tunneldataindicatedthatmostoftheadv~tageofPorous-leading-edgesuctionontheNACA24I2airfoilcouldbe obtainedwithavalueof CQ of 0.002whichcorrespondsto an inflowvelocityof3.6fpsat anairspeedof 63mph. Thedesignporositywassuchthata pressuredifferenceof72.8lb/sqf%wouldproducea velocityof3.6fpsthroughtheporousmaterial.Thearithmeticmeanof 20 readingsofporosityofonlythefilterclothshoweda velocity3 percentabovedesignvelocityatdesi~pressuredifference(moreporous).Thecopperscreenandperforatedbrassdclnotappearto addappreciableresistance.

Figure2(a)showsthegeneralarrangementof equipmentandductingintheairplane.Theleadingedgeofthewingwasporousover83.4per-centofthespanandthefirst8 percentofthechordontheuppersurfaceas showninfigurel(b).Theleading-edgeductwasformedbytheincorpo-rationofa falsespar,ductbottom,andporousmaterialsupportsasshowninfigure2(b). Theporouscoveringwasattachedattheedgesinsectionswithmachinescrews;theedgeswerefairedwithmodelingclayandshellacked,as showninfigure2(c).,A portionof thewindowoverthepilot’sheadwasreplacedby a pancoveredwithporousmaterial,SEshownin figurel(b),inorderto continuetheareasuctionoverthecentersection.Theundersideofthepanandpartoftheductingareshownin figure2(d).Theflowwasremovedfromeachwing-leading-edgeductatthewingrootby theductshownin figure2(e)whichincorporatedturningvanesinthe90°bend;theflowwasthenfurtherductedtothebloweras shownin figure2(f). Thesmallductshowninfigure2(f)isthecontinuationoftheductfromthecentersectionshowninfigure2(d).Fromtheblowerexit,theflowwassplitandwasexpelledfromtheexitholesonthesideofthefuselageas showninfiguresl(a)and2(a).Twobutterfly-typeshutterswereinstalledintheexitductsbehindtheblower.

Theblowershownin figure2(f)isthecompressorstageof a largeaircraft-engineturbosuperchargerwhich,thoughnotideallysuitedtothisapplication,wasusedbecauseitwasreadilyavailable.Theblowerwasdrivenby a smallautomotiveenginerated25 horsepowerat 4,400rpmanda right-anglegearboxin sucha mannerthattheblowerspeedwasthreetimesthatoftheengine.Theengine-blowerinstallationis shownin figure2(g). Engineandexit-ductshuttercontrolsweremountedonthetopoftheenginecoveras canbe seeninthisfigure.Thelouversinthetopofthefuselagejustbehindthewing,showninfigurel(c),wereinstalledto removeenginefumesfromthecabin.

Duringtheinvestigation,largedeflectionsoftheporoussurfaceoccurredwhensuctionwasappliedin configurationswherelargeportionsoftheporousareaweresealed..!I’hisconditimrequiredadditionalstiffenerstoreducetheunsupportedlengthof theporousmaterialfromtheapproximately30-inchspanwiseincrementsshownin figure2(b)to

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6 NACATN3062

about10inches.Theseadditionalsupportsweremadeofthinduraluminplacededgewiseto theporousmaterialwiththeedgeshsrpenedto reduce Hinterferenceofthesupportto theflow.Thesupportswere1 inchwidenormaltothewingsurfaceandhadtheloweredgeflangedto stiffenthesupportandto assisttheflowtoturninboardafterpassingthroughtheporousmaterial.Photographsofthenormalleadingedgeandleadingedgebuckledby suctionareshowninfigure3.

Instrumentation

StandardNACAinstrumentationwasprovidedto recordcontinuouslyairspeed,threecomponentsofacceleration,rollingandpitchingveloci-ties,sideslipangle,angleof attack,controlpositions,controlforces,temperatures,angleofbankorpitch,airplaneheading,andpressures.Theairspeedusedinthispaperis calibratedairspeedasobtainedbymeasuringpressuresfroma total-pressuretubeanda swivelstatic-pressuretubermauntedona boom1:chordsaheadoftheleadingedgeoftherightwing

(fig.1)sndby correctingthosepressuresforpositionerroras deter-minedfroma trailingbomb. Theangleofattackandangleof sideslipwereobtainedby useoffree-floatingvanesmountedon a boom12chords

4aheadoftheleadingedgeoftheleftwing(fig.l(a)).Theanglesreadfromtheangle-of-attackvanewerecorrectedforrollingandpitchingvelocitiesanderrorduetotheinducedflowfieldaheadoftheairplane.

Staticpressuresweremeasuredatthreespanwisepositionsalongtherearwardwall,atonepositionontheoutboardendwallof oneleading-edgeduct,sndatonepositionintheblowerexitduct.Theorificeontheoutboardendwallisreferredto subsequentlyastheoutboardmeas-uringstation.Flowquantitiesweremeasuredin eachofthethreelongi-tudinalductsby usingtotalpressureandtheaverageof fourstaticpressuresin eachofthelargeductsandby usingstaticpressureattheentryandthroatofa venturiinthecenter-sectionduct.Temperaturesoftheflowinoneofthelargeductsandinthecenter-sectionductwerealsorecorded.A surveyoftotalpressurewasmadeacrosseachmainductpriortotheflightteststo determinethevelocitydistributionintheseducts. A dischargecoefficient,estimatedat0.974,wasusedindeter-miningthevelocitythroughtheventuriinthecenter-sectionduct.

Tuftpicturesoftheflowoverthewingweremadewitha rearward-facing35-millimetermotion-picturecamerawhichwasnmuntedaboveandbehindthewingonthestructureshowninfigures1(%)and2(c)andwhichphotographeda sphericalmirrorthatreflectedan ima5 oftheentirewing.

I/

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NACATN 3062 7

TESTS

Flighttestsweremadeto determinethepowerreqtiements,theeffectof vexyingsuctionflow,andtheeffectofvaryingtheextentofporousareaontheliftcoefficientandangleof attackatthesta~ inthecourseof accrmndatingflighttimeontheporoussurfaces.Stallsweremadeatfourdifferentblowerspeedsineachofthefollowingconditions:airplsneenginewitha manifoldpressureof2’5inchesof~rcury,at2,200rpm,flapsup anddown,andairpbneengineidling,flapsup anddown. Allflightdatapresentedinthisreportwereobtainedaftertheadditionalchordwisestiffenerswereinstalled.Inmskingtheflighttests,theblowerwassetat a predeterminedspeedata flightspeedofapproximately85to90 mphandno furtherchangesinblowercontrolsettingweremadeduringthesubsequentstallapproach.Theresultwasapproximatelyconstant-volumeflowthroughtherangeof airspeedobtainedduringeachtest. Thevariousspanwiseandchordwiseextentsof suctiontestedareshowngraphicallyinfigure4. Theextentofporousareawasvsriedby sealingportionsoftheporoussreawithcellulosetape.Theratioofwingareasffectedby suctiontototalwingareaasdeterminedby thespanwiseextentofporousareaandtheratioofporousareatototalwingareaarealsogiven.Inorderto determinetheeffectofwateron theporousmaterial,oneflightwasmadewithleading-edgeconfigura-tion(a)(fig.4)inrainofvaryingintensity.

Testsweremadeonthegroundatvarioustimesduringtheprogramtodeterminetherelativeporosityandpowerrequirementsoftheporoussur-faceasaffected%y time,flighttime,andwater.Thesetestsweremade .by runuingthebloweratvarioussteadyrotationalspeeds.Rainwassimulatedin someofthesegroundtestsby sprayingthewingwithwaterandtakingrecordsatfullthrottleandalsoby firstwettingthewingandthenstsrtingtheblowerengineat fullthrottle.All~oundtestsweremadewithleading-edgeconfiguration(a)(full8 percent).

RESULTSANDDISCUSSION

PracticalProblems

Sincethisinvestigationwasa researchprojectto determinethepracticabilityoftheporoussurface,theweightandvolumeofthecompo-nentsotherthantheporoussurfacewerenotgivenmuchconsiderationsolongastheywerenotexcessive.As a result,theweightoftheairplanewithboundary-layercontrolwaslarge.An appreciablereductioninweightswouldhavebeenpossiblehadanairplanebeendesignedespecially

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8 NACATN3062

fortheboundary-layer-controlinstallationandhadoneofthehigh-power-to-weight-ratioblowersystemsnowavailablebeenused. WeightsoftheprimarycomponentsaregivenintableII.

Porosity.-Dataaffectingtheporosityoftheporousleadingedgeasdeterminedfroma numberof groundtestsareshownintableIII. Theresultsofthetestssreshowninfigure5 plottedasapparentvelocitythroughtheporousmaterialagainstthepressuredifferenceacrosstheporousmaterial.Comparisonofthedataoftests1 and2 indicatesnolossinporosityafterapproximately12hoursof flighttimeand89 daysofbeingparkedin a ratherdustyhangar.Dustthereforeseemstohaveno adverseeffectsonthepractic&bilityofthistypeofporotisurface.Theapparent@n inpawsitybetweentests1 and2 maybe takenasanindicationoftheaccuracyofmeasurement,withthetrueporositycurvelyhg somewherebetweenthetwofairedcurves.Thelossofporosityshownby thedataoftest3 maybe attrilnrbedto theretentionofadhesivefromthecellulosetape,whichwasusedto varytheextentofporoussrea,afterthetapehadbeenremoved.Testsmadeafterthefirsttwoattemptsat cleaning(tests4 and5) apparentlysucceededonlyjn drivingtheadhes-ive deeperintothesurfacewithsuccessivelossesinporosity.Iatertests(tests6,7, and8)madesfteradditionalattemptsat clesningandadditionalflighttimeshowedslightincreasesinporosity,buttest9madeneartheendoftheflig@ investigationshowedan appreciableincreaseinporosity.No cleaningwas“attempted%etweentests6 and9.Theexplsnationappearstobe thatthesolventscontainedintheadhesiveparticlesdriedoutandpetittedtheremovaloftheresidueby airandby,airandwatermixtureswhichpassedthroughtheporousmaterialduringflightandgroundtestsjustpreviousto test9.

Theshapeofthecurvesinfi~e 5 givessomeindicationof thetypeofflewthroughtheporousmaterial.Thestraight-linecurveshavingtheiroriginsat zerofortests1,2,3, and9 indicatethattheflowthroughthescreenforthesetestswasnmstlyviscous.Althoughstraightlinescouldreasonablybe fairedthroughthedatafortheothertests,extrapolationofthelinesdidnotpassthroughzerovelocityat zeropressure.Onesetofdataforwhichpointsinthelowvelocityandpres-surerangewereavailable(test8) showsappreciablecurvatureinthisrange,snindicationofa transitionfrommostlyviscoustomostlyturbu-lentflow.A seeminglyreasonableexplanationforthischangeisthat,astheeffectiveTorousareawasreducedby partialblockingof someofthepassagesintheporousmaterial,thecriticalReynoldsnmbed oftheflowthroughtheporousmaterialwasreachedsndtransitionto turbulentflowoccurred.

Effectsofrdn.- Theeffectsofrain,realandsimuhted,ontheporousmaterialareshownin figures6 and7. Figure6 showsa comparison ‘of groundandflighttestswherethedataforthedrygroundtestaretakenfromtest8 (seefig.5). An explanationforthelargedifference u

—.

2xNACATN 3062 9

inpressuredifferentialbetweenthedryandwetconditionsforthegroundandflighttestsmaybe thatthesimilatedrainforthegroundtestswasmuchheavierthantheactualrainencounteredin flight.Theinter-ceptofthedashedlinesfortheflightdatawiththepressurescalerepresentsa reasonablevalueoftheaveragepressureontheexternalsurfaceoftheleadingedgeinflightas determinedby themethodexplainedintheappendix.Thepressuresforthegroundtestsrepresentthepres-suredifferenceacrosstheleadingedgeonly,whereasthefllghtpressuresincludethepressuredropabovethewing(estimated63 lb/sqft). Fig-ure6 showstheincrementinpressureproducedby simulatedheavyrainin groundteststobe approximatelyequalto thepressuredropabovethewinginflight.Thus,forflightinheavyrainthepressurewhichtheblowerwouldhaveto overcomewouldbe approximatelytwicethatforflightinthedrycondition.Thisincrementwasoftheorderof50per-centforthelightrainencounteredin flight.

Figure7 showsa comparisonoftwogroundtestsinwhichtheblowerenginewasstsrtedatfullthrottle.Thenumbersalongthecurverepre-senttimein secondsfromstarting.Nowaterwasaddedto theleadingedgeforthewetconditionafterstsrting.It appearsthat,undertheseconditions,theporousmaterialwouldhavecompletelycleareditselfofwaterwithin3 to 4 minutes.

mom theseresults,rainappearsto be a veryimportantfactorwithregardtothepracticabilityofporous-leading-edgesuction.A suctionsystemhavinga blowerwhichoperatedat designpressureratioindryair,aswouldprobablybe thecaseforotherthanexperimentalsystems,wouldbe greatlyhihderedinrain,sincetheblowerwouldnotbe capableofproducingtheadditionalpressuredropneeessaryto overcomethesur-facetensionofthewaterintheporoussurface.Theblowerusedinthisinvestigationwasbeingoperatedatpressureratiosoftheorderofone-fourthitsratedpressureratio;thus,theadditionalpressuredropwaswellwithinitscapabilityinasnmchastheblowerefficiencyapparentlyincreasedgreatlywithincreasingpressureratio.Duringthegroundsimulatedraintests,an appreciableamountofwatercouldbe seencomingoutofthefuselageexitducts.Thisconditionwouldappearto obviatethepracticabilityofusinganywater-absorbingmaterialsuchas feltforanypartoftheporoussurfacesincethewaterwouldprobablygreatlyincreasethedensityoftheporoussurface.Apparently,additionalworkshouldbe doneontheeffectofrainonporous-areasuction.

Powerrequirements.-Thepowerrequirementswerecalculatedastheproductofvolumeflowrateanddifferenceintotalpressuremeasuredatanytwostationsbetweenwhichtheincrementofpowerwssdesired.Theestimateddistributionofpowerfortheglidingcondition(aircraftengineidling,flapsup)withleadhgzedgeconfiguration(a)atmaximumblowerspeedazthestallisshowninfigure8.

10 NACJITN3062

Sincenowing-surfaceorificeswereprovided,thedivisionofthetheoreticalaerodynamicsuctionpower(calledusefulpowerhereinforsimplicity)intopowerrequiredto overcomeporous-materialdragandpowerrequiredto reduceductpressureto averagesurfacepressurewascalculated.Theestimationoftheleading-edgesurfacepressurefromwhichthepressuredropequivalenttothesetwopowerrequirementswasdeterminedisgivenintheappendix.Themaximumtheoreticalaerodynamicpower,ifductlossesareexcluded,veriedwiththeconfi~ationstestedfrom3.65to 9.7ohorsepower.Thepressuredropproportionaltotheductpowerlossshowninfigure8 waspartiallymeasuredandpartiallycalcu-lated.Ductlosswasmeasuredbetweentheoutboard-ductstaticorificeandthevelocity-meas~ingstationinthewingroot.Ductlossesfromthisstationtotheblowerendfromtheblowertothefuselageexitswerecalculatedwiththeaidof reference4. Thecalculatedductlossamountedto aboutkopercentofthetotalductloss.

Thepowerto driveaccessorieswasestimatedtobe 1 horsepowerandthegesrboxefficiency-sassumedas98percent,whichisveryreasonableforthespiralbevelgearsused.Theenginepowerwastakenfroma powercurvewhichwassuppliedbytheenginemanufacturerwiththeengineandwhichwascheckedandfoundtobe reliable.Theblowerlosswastakenasthedifferencebetweentheenginepoweroutput(ata particularrotationalspeed)andthetotalofotherpowerrequirementsgivenpreviously.Themsximumobtainableenginerotationalspeedwasappreciablylimitedbympropermatchingof enginetorqueoutputandtorqueinputrequiredbytheblower,sothatatno timewasfull-ratedpoweroutputoftheengineobtained.

TableIV showsthevariationwithblowerspeedandleading-edgeconfigurationoftheratioofusefulpowerto engineout~utpower,theratioofporous-materialpowertousefulpower,theapproximateratioofductpowerlossto engineoutput,andtheapproximateblowerefficiency.Valuesofengineoutputpowerandflowcoefficientforeachcae arealsogiven.

AerodynamicData

Effectof suctiononmaximumlift.-A sunmmryofthemainaerodynamicdataobtainedduringthisinvestigationis showninfigure9 asthevaria-tionof liftcoefficientwithflowcoefficientforvariousextentsoftheporousleadingedgeandvsriousairplaneconfigurations.Thefirstpointtobe notedisthatthereisan initialdroph liftcoefficientfromthecompletelysealedconfi~ationto thezero-suctioncase(ductdampersclosed)withallleading-edgeconfigurationsexceptconfi~ation(e)(centersectiononly)andconfi~ation(f)(last1 percent)in fig-ures9(d)and9(e),respectively.Theapparentreasonforthisbehavioristhata circulatoryflowissetup throughtheporoussurfaceasa

.

NACATN 3062 Xl

resultofthelsrgepressure~adientabovetheporousarea.‘Thiscircu-latoryflowevidentlyhastheeffectofpronmtingseparationata lowerangleof attackthanthatatwhichitwouldoccurifthisflowdidnotexist.Figure10showsthetheoreticalpressuredistributionovertheuppersurfaceoftheleadingedgeoftheNACA2412airfoilata liftcoefficientof 1.6. Thedifferenceinpressuresoverthefirst1 percentmaybe seentobemuchlessthanthedifferenceinpressuresoverthefull8 percentsothattherewouldbe lessopportunityforlocaloutflowto occuroverthefirst1 percent.As thechordwiseextentofporousareawasvariedfrom8 percent(configuration(a))infigure9(a),to2 percent(configuration(b))in figure9(b),andfinallyto 1 percent(configuration(c))infigure9(c),theinitialdropin liftcoefficientbecsmeprogressivelyless.Figure10showsthatthemaximumdifferenceinpressurecoefficientsoverthechordwiseextentsofporousareavariedinthesamemanner,thedifferencesbeingoftheorderof 4.25for8 per-cent,1.95for2 Tercent,and0.80for1 percent.

A porousmaterialhavinglessover-allporositywouldreducethelocalcirculationandhencetheinitialdropin liftcoefficientwiththebloweroff,butwiththebloweroperating,lsrgerpowerrequirementswouldbe needed.

Afternotingtheinitialdropsin liftcoefficientobtainedonpreviousconfigurations,configuration(f)(last1 percent)wastriedinan effortto reducetheinitialdropwhilemaintainingsomeoftheaddi-tionalliftdueto suction.Figure10showsthatthemaximumchangeinpressurecoefficientforthisconfigurationwouldbe oftheorderof0.18as comparedwith0.80forconfiguration(c)(first1 percent).Fig-ure9(e)showsthattheinitialdropin liftcoefficientwaslessforconfi~ation(f),aswasexpected,butthatno subsequentgainin liftcoefficientwithsuctionwasobtained.

Anotherpointworthnotingisthatacoefficientoccurredwithairplaneengineenginepoweroffand,generally,a higherrequiredtoregainthisinitialliftloss

largerinitialdropin Mftpoweronthanwithairplanevalueof flowcoefficientwaswithairplaneenginepoweron.

A comparisono,fthevariousdatapresentedinfi~e 9 indicatesthatnoneoftheleading-edgeconfigurationstestedwasclesrlysuperiorwithregardto increasingthemaximumliftcoefficient.Althoughtheincrementin liftcoefficientfora givenincrementinflowcoefficientwasgreaterforsomeconfigurations,theinitialdropin liftcoefficientwasgenerallylargerforthosesameconfigurationssothatthemaximumliftcoefficientwiththemaximumsuctionavailableremainedmuchthesameformostoftheconfigurationstested.Hadthesesameextentsofporousareabeentestedon a sharp-nosedairfoilwhereleading-edgesepa-rationismorelikelyto occurthanwiththerelativelybluntleadingedgeoftheNACA2412airfoil(seefig.l(d)),theresultswouldundoubtedlyhavebeenmuchmorefavorable.

——. — —..

12

Itwillbe notedthattherearethree“fun 8 percent.” Thedataof figure9(a)

NACATN 3062

partsoffigure9 labeledwereobtained~ustafterthe

installa~ionoftheadditionalleiding-edgestiffener-andthoseof fig-ure9(g)wereobtainedduringa flightinrainmade184daystotaltime,18hours9 minutesflighttime,afterthatforfigure9(aJ. Thedataof figure9(h)wereobtained2 daysaftertherainflightforcomparisonwiththerainflight.Becausetheintensityoftherainvariedfromadrizzleto ratherheavyrslnduringtherainflight,notverymuchcanbe gainedfromsucha comparison.Onepointwhichappesrsworthyofco~arison,however,isin connectionwiththeinitialdrop h lift coef-ficient.Thisinitialdropis lessfortheraindata(fig.9(g))thanforthedry-airdata(fig.9(h)or9(a)).Thisdifferenceistobeexpectedinasmuchastheraintendsto increasetheover-alldensityoftheporousmaterialandthusreducesthelocalcirculationthroughit.

l?iguxes9(a)and9(h)providea bettercomparisonsincethecondi-tionsweremoresimilar.A totaltimeof 186days,a flighttimeof19hoursk6minutes,occurredbetweentheflightsfromwhichthesedatawereobtained.Theonlymajordifferencebetweenthesedataisthegreaterinitialdropinliftcoefficientforthedataof figure9(h).Thisdifferenceisprobablya consequenceofthehigherporositywhichexistedforthelasttestsmade[seetests8 and9, fig.5).

Earlytuftpicturesshowedthatthestalloriginatedatthetrailingedgeofthecentersectionwithpoweroffandjustinbosrdoftheaileronswithpoweron. Configuration(e)(centersectiononly)andconfigura-tion(g)(outboardsealed)weretested~ ~ attemPtto ~luence theoriginofthestallbut,asis discussedsubsequently,thetestswereunsuccessful.h obtainingdatawithconfi~ation(d)(fi$=9(d))~aseverevibrationoftheleadingedgeontheotierpanelsoccurredwhich,forthemaximumblowercondition,couldbe seenwiththesldofa mirrorandcouldbe heardoverthenoiseoftheairplaneengineandtheboundary-layer-controlenginesndblower.Theresultingpressurerecordsweresuchthatnovaluesofflowcoefficientcouldbe obtainedforthemaxim.m-blowerconditionand,therefore,estimatedvaluesofflowcoefficientswereusedforthiscondition.Thevibrationoftheleadingedgewassoviolentthatthepilotandengineer-observerdeemedit advisabletoterminatethemaximum-blowertestsbeforecompletion.Thepressurerecordsindicatethatthevibrationcontinueddownthroughtheblowerspeedrangebutwithmuchreducedviolencesothatitcouldno longerbe seenorheardandthepressurerecordsbecamsreadable.Apparently,thesealedouterductsactedas closedorganpipesandreinforcedthepressurepulsesoriginatingattheblower.Thevibrationoftheleadingedgemayhavebeenat leastpa$tlyresponsibleforthelossof liftwithincreasedsuctionshowninfigure9(d).

Thedataforconfiguration(g)(outboardsealed)showninfigure9(f)areverysimilarto datafortheoriginalfu~-8-percentconfiguration “

NACATN 3062

of figure9(a)exceptthatslightlylessandtheliftslightlygreater.

J-3

theinitialdropin liftcoefficientiscoefficientsatmsximumblowerspeedare

Comparisonof flight andwind-tunnelresults.-A comparisonof someresultsfromtheflight-testinvestigationwiththosefromunpublishedtwo-dimensionalwtid-~el dataobtainedbeforebeginningtheflightinvestigationis showninfigureIL. Thewind-tunnelmodelwasa 36-inch-chordmodelof theNACA24I2airfoilsectionwitha porousnoseconsistingof filtercloth,similartothatusedontheairplane,backedwithsin-teredbronzeforstiffness.W@d-tunneldatawereobtainedat a speedof78.5mph. Fortheparticularresultsshown,thenoseofthew@d-tunnelmodelwassealedfromtheleadingedgetothe0.4-percent-chordstationandwasopenforthenefi7.3~ercent.Thiswind-tunnelconfigurationwastheonenesrestthe8-percent-openconfigurationusedontheair-plane.Theflightdatausedwereobtainedwithairplaneenginepoweroffandfhps Up. A comparisonof leading-edgeporositiesapplicableto theflightandwind-tunnelresultsisshowninfi~ n(a). Thecme forthewind-tunnelresultsrepresentsonlya smallportionofthevelocityanddifferentialpressurerangetested.Thetwoeetsofdataarecon-sideredtobe in goodenoughagreementfora reasonablecomparisonofaerodynamicresults.Figuren(b) showsthevariationofmaximumliftcoefficientwithflowcoefficienttobe ofthesameorderofmagnitudeforthetwosetsofdata.Theinterceptofthewind-tunnelcurvewithzerosuctionwasnotavailablebutthetrendindicatedbythedashedlinewasestimatedfromotherresultsfromthesameinvestigation.Thetind-tunneldatashowa netgainin liftcoefficient(fromthesealedcase)of only0.25attheoptimumvalueof CQ = 0.002. An interestingobserva-tionisthatalmostthesameincrementin liftcoefficientwasobtainedin flightwiththemaximumavailableflowcoefficient,althoughthetrendindicatesthata largerincrementin liftcoefficientwouldhavebeenobtainedhadhigherflowcoefficientsbeenavailable.

Tuftpictures.-Figure1.2showsa typicalfrsmefromtuftphoto-graphs.Thisframewastakenduringtheflightwiththeleading-edgeconfiguration(b)(first2 percent)in a semistalledcondition,withpoweroff,andwithflapsdownatthemaximum-suctioncondition.Asmentionedpreviously,thetuftpicturesweretakenby a csmeramountedaboveandbehindthewing,facingrearwardandupward,andshootingintoa sphericalmirror.Althoughtheuseofthesphericalmirrorresultedinappreciabledistortion,itwasusedbecauseitpermittedanimageoftheentirewingtobe obtainedwitha singlecamera.Thechordwisestripsonthewingwere27.25inchesapart(approximately12.5percentofthesemispan).

Stallpatternsweresimilarfora givenpowerconfigurationregard-lessof leading-edgeconfiguration,amountofsuction,orflapposition.In general,thestalloriginatedattherightsideofthecenter-section

.___— .—.—— ——- — --—-—, —-—— .——————----—- ———-——————

14 NACATN3062

trailingedgewithpoweroffandatthet%ailingedgejustinboardoftheaileronswithpoweron. Thestalledsreasspreadforwardandspanwiseina triangularfashion.Suchdifferencesin stallpatternaswereobservedcouldnotbe definitelycorrelatedwithflapposition,leading-edgeconfig-uration,or smountof suction.

CONC17JDINGREMARKS

Resultsofthisinvestigationhaveindicatedthat a practicalwinghavingporous-leading-edgesuctioncanbe constmctedwhichhassufficientstrengbhanddurabilityforuseinflightwithoutaddingexcessiveweight.Forthetypeofporousmaterialusedinthisinvestigation,cloggingdueto atnmsphericdustdidnotappeartobe a problem.Forthelightrainencounteredinflight,thepowerrequiredto producea givenflowcoef-ficientwasabout50percentmorethanthatrequiredforthedrycondition.Bssedonthegrounddata,itwasestimatedthatforflightinheavyrainthepowerwouldbe approximatelytwicethatforthedrycondition.Atmsximumblowerspeed,however,theporousareabecameclearedwithin3 to4 minutesafterwaterceasedto impingeonthesurface.Undercertainconditions,testsshoweda severevibrationof theporousmaterialinducedby w “organpipe”resonanceoftheanticolumnwithintheducts.Asexpectedfrompreviouswind-tunnelresults,theuseof leading-edgesuctionwiththesmallamuntofpoweravailableandwiththewell-roundedairfoilsectionused(NACA24I2)hadMttleeffectonthemaximumliftcoefficientdeveloped.Ingeneral,an appreciabledropin mximumliftcoefficientoccurredfromtheleading-edge-sealedconfigurationto theconditionofzerosuctionwiththeporous-sreaconfigurationstested.Incrementsinliftcoefficientdueto thesuctionavailablegenerallybroughtthemsxi-mumliftcoefficientbackapproximatelyto thevalueforthewingwiththeleadingedgesealed.Themaximumtheoreticalaerodynamicpower,ifductlossesareexcluded,variedwiththeconfigurationstestedfrom3.65to9.70 horsepower.

LangleyAeronauticallaboratory,NationalAdvisoryCommitteeforAeronautics,

IangleyField,Vs.,October26,1953.

“

NACATN 3062 15

APPENDIX

ESTIMM’IONOF LEADING-= SURFACEPRESSURE

Sincenowingsurfaceorificeswereprovided,thedivisionofthetheoreticalaerodynamicsuctionpowerrequired(calledusefulpowerhereinforsimplicity)intopowerrequiredto overcomeporous-materialdragandpowerrequiredto reduceductpressureto averagesurfacepres- .surewascalculatedinthefollowingmanner:Thepressureintheduct PIforbloweridlingandwithexit-ductshuttervalvesclosedisassumedtobeequaltotheaveragepressureovertheporousarea p atthesamevalueof liftcoefficientwiththebloweratmaximumspeed.Inordertodeterminetheaveragepressureovertheporousareaat somehighervalueof liftcoefficientwithbloweroperating,thispressureisexpressedintermsofpressurecoefficientS by meansoftheequationS = (% -P)/qcwhere ~ and qc arefree-streamtotalandcalibratedimpactpressures,respectively.Thepressurecoefficientis correctedtothepropervalueof liftcoefficientby themethoddescribedbelowandthenewsurfacepressuremaythenbe calculated’.

Theprocessof correctingforliftcoefficientconsistedof calcu-latingtheoreticalpressurecoefficientsforthewinguppersurfaceatvariousvaluesof liftcoefficientobtainedfromdatainreference5,integratinganddeterminingtheaveragepressurecoefficientoverthefirst8 percent,andplottingtheseaveragepressurecoefficientsagainstliftcoefficient.Thepressurecoefficientdeterminedfromflightdatawithoutsuctionis locatedonthisplotat itscorrespondingliftcoef-ficientanda curveparalleltothecalculatedtheoreticalcurveispassedthroughthetestpoint.Thepressurecoefficientattheliftcoefficientformaximumblowerspeedcanthenbe pickedfromthisnewcurve.Withthesurfacepressurep thusdetermined,thepressuredifferenceacrosstheporousmaterialis

AP=P- P1

andtheiniti”alpressuretobe overcomeby thebloweris

~-p=sqc

Theseequationsarebasedontheassumptionthatthedynamicpressuredoesnotassisttheflowtopassthroughtheporousmaterial.

——— .—..-—— — ~—— -—- ———

ItEFERmms

NACATN 3062

1.Jones,Melvin,andHead,M. R.: TheReductionofDragby DistributedSuction.ThirdAnglo-AmericanAeronauticalConference(Brighton),Sept.4-7,1951,pp.199-230.

2. Raspet,August:BoundaryLayerStudieson a Sailplane.PreprintNo.348,S.M.F.FundPreprint,Inst.Aero.Sci.,Jan.-Feb.1952.

3. Miles,F. G.: SuckingAwaytheBoundaryLayer.Flight,vol.X#Pl,no.1570,Jsn.26,1939,PP.82b-82d.

4. Henry,JohnR.: DesignofPower-PlantInstallations.Pressure-LossCharacteristicsofDuctComponents.‘NACAWRL-208,1944.(FormerlyNACAARRL4F26.)

5. Abbott,IraH.,VonDoenhoff,AlbertE.,andStivers,IouisS.,Jr.:~ ofAirfoilData. NACARep.824,1945. (SupersedesNACAWR L-560.)

3X17

----- -- ——. -—.-. .-—. —.—-— —— .—-—-. —I’ABM lo- lJWSIUNAL

approximatetake-offweight,lb . .Horsepower(at2,200rpm). . . . .Propellerdiameter,ft . . . . . .Over-alllength,ft . . . . . . . .

wing:Area(includingfuselage),sqftSpan,ft . . . . . . . . . . .Dihedral,deg. . . . . . . . .Aspectratio ... . . . . . . .Taperratio. . . . . . . . . .Meanaerodynamicchord,ft . .Incidence,deg . . . . . . . .Washout,deg . . . . . . . . .Airfoilsection. . . . . . . .Flapsrea,sqft.... . . .Aileronarea,sq ft . . . . . .Flapdeflection,down,deg . .Ailerondeflection,deg. . . .

Horizontaltail:Aspectratio . . . . . . . . .Totalarea,si ft...... .Stabilizerarea,sqft . . . .Elevatorarea(lesstab),sq ftElevatortabsrea,sqft . . .Airfoilsection. . . . . . . .

.

.

.

.●

✎

✎

✎

✎

✎

✎

✎

✎

✎

✎

✎

✎

✎

Taillength(centerof gravitytoElevatordeflection,deg:up . . . . . . . . . . . . . .Down . . . . . . . . . . . . .

Elevatortabdeflection,deg:up . . . . . . . . . . . . . .Down . . . . . . . . . . . . .

Incidence,deg . . . . . . . . .

Verticaltail:Aspectratio . . . . . . . . . .Totalarea,sqft . . . . . . . .Finarea,sqft . . . . . . . . .Ruddersrea,sqft . . . . . . .Airfoilsection. . . . . . . . .Rudderdeflection,deg . . . . .Taillength(centerof gravitytoFinoffset,deg...... . . .

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elevatorhinge,

. . . . . . . .

. . . . . . . .

..*,. . . .

. . . . . . . .

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. . . . . . . .

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.,

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✎ ✎

✎ ✎

✌

✎ ✎

✎ ✎

✎ ✎

✎ ✎

✎ ✎

✎ ✎

✎ ✎

✎ ✎✎

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.

.

.

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.●

✎

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✎

✎

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.approx.),

. . . . .

. . . . .

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. . . . .

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. . . . .

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. 3,830

. .

. . 7%

. 27.10

. 218.u

. 36.17

. .

. . 6:;:,. 0.62. . 6.30. . 1.0. . 1.5NACA24ti. . . 8.68. . 12.32. . . 45. . . 95

. . .3.16

. . 35.20

. . 19.79

. . 14.660.75

“i& 0006ft. 18.0

.0 . 31.5

. . . 13.5

. . . .

. . . . E

. . . . -4

. . . 0.88

. . ~6.55

. . . 8.78● 7.77

“N~CA0006. . . Wl

rudderhinge,approx.),ft . . 18.3. . . . . . . . . . . . . . . . . 0

aDesigngrossweightof originalairplsne,lb . . . . . . . 3,350

. ..— -——. .———-- — — — ...—————— –— —-——. -——

TABLEII

COMPOMEMTWEIGHTS

[Allweightsinpoundd

Poroussurfaces:Total. . . . . . . . . . . . .Centersection. . . . . . . .Eachwing. . . . . . . . . . .

Completewingwithboundary-layer(includingporoussurfaces):Withoutfuel . . . . . . . . .%ith 61gallonsfuel . . . . .

Completewing,originalairplsne:WithoutMel . . . . . . . . .With76gallonsfuel . . . . .

. . . . .

. ...*

. . . .

control

. . . . .

. . . . .

. . . . .

. . . . .

.

.

.

.

.

.

.

Boundary-layer-contnlequipmentinfuselageEngine . . . . . . . . . . . . . . . . . .Blower . . . . . . . . . . . . . . . . . .Gearbox . . . . . . . . . . . . . . . . .Mount. . . . . . . . . . . . . . . . . . .Ducking. . . . . . . . . . . . . . . . . .Accessories(coolingandlubrication,etc.)

Instrumentation. . . . . . . . . . . . . . .Instruments. . . . . . . . . . . . . . . .Batteriesandinverter. . . . . . . . . .Wingbooms(includingpickupheads). . . .Csmera,mirror,andmountingstructure. .

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..

Mountingboards,cables,relays,tubing,etc.

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. 3:.;

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. 15.0

403.25769.25

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.

295.5751.5

458.8153.078.842.347.330.0

107.4

%Cheductingnecessitateduseof smallerwingfueltanks.

.

NACATN 3062 19 ●

TABLEIII

POROSITYTESrs

.

.

@l por..itytestswererunonthegroundwiththeleading-edgeconfigurationlistedinfigurekascotiiguration(a)(til8percentopen)~

Flighttimesince~otdthe SticeTest previoustest previoustest, Remarks

HoursMinutes days

1 0 0 Madeatbeginningofprogram

2 11 53 89 AI1flights,fuu8percentopen

3 13 41 11.3 Divisionofflighttimeasfollows:7’hr43rein,u 8percentopen1hr02ti, completelysealed2hr51rein,first1percentopec2hr05rein,first2percentopen

4 0 0 Removedalltapeandcleanedbyrubbingsurfacewithlhcquerthinneroncloth

5 0 0 Sprayedsurfacewithprep-sol

6 0 1 Sprayedsurfacewithbenzene

7 0 28 Additionalstiffenersinstalled;sprayedcarbontetrachloridethroughbothsidesofporousmaterialwhileremwedfromwing

8 17 43 32 Divi_sionofflighttimeasfollows:k b olmin,tiIJ.8percentopen2 hr41rein,first2percentopen3 kc39rein,firstlpercentopenOhr51*, leadingedgesealed1hr42rein,centersectiononlyopen2h 21rein,last1percentopen2hr33rein,outboardsealed

Limitedattemptsatclean~.madebetweenflights

9 7 00 169 Approx.l&r inrainofvaryingintensity;fu~8percentopen

50 17 431

—— .——- —

Leading-edgecotiiguratIon

Full 8 percentopen

First 1 percentopen

First 2 percentopen

Laet 1 percentopen

OutboerdsealedFUll 8 percentIn rain

)~1 8 percentopen

Blower

L

[

blaxiuruJn2/31/3

Minimum

M.xilmlm

Keximm

MEMmlLl

Mawnurn

0.275,217’.168.054.436

,447

,472

.272

.323

.259

TABm Iv

FW%ER R3mRJlMEN16

0.332 0.0517.282 ,0304.185 .0038.M!4 o.430 ,0302

.39 I .0477

,4$Z? I .OI.25

.366 I .0299

.228 ,0326

.310 .0463

Blnwer)fficiencypercent

.@F!PE4

33.527.0i8.96.0

50,7

53.9

53.0

32.838.9

33.3

Engineoutput,llp

15,812.59,19.0

17.7

16.8

X),7

14,914,7

14.1

Flowcoefficientat btall

o.oo131.00098,00056,00020,00110

.0CQ76

.00114

.00110

.oo1.13

aBlowerveriationfB de6cribedaccordingto an approximatevariationof rotationalspeed.

%hee titswere obtainedat end of fll~t promem after flightin rain and are presentedforcomparisonwith otherdataobtainedearlyin-fll-@t-programfor .&e conflgmation. -

!2

II

I

I

I

I

I

1

I

.- ..-.“.- r--r —-.

:. -—

* 1 I,,.;”--

k ?’

::._&~=.=_5 ‘ --’-~’~=%. -

-%.. .->.$+. “L :7,

..?_* ‘“’ ~.. -.. ‘t-i- “-- 7--”(_&----___L-z= ..,.,.*...ZEG=5r“--”’ -2— .. ..-.

-. --- --e.. ,.. -

I—. . -. ..i

(a) one-quarter front view. 11-70267

Figure 1.- Ce6ma 190airplaneusedforflight teats.

~

,/

.,-*

,.8

.+.. ,

,,

, ,,

d’

*

L-71602 Q(b) View fmm above. g

Figme 1.- Continued.N

23

t---- ‘0”541,,

.——. —.

-hr’4.70

———————740

Z_All dimensions in feet

— 36.17~

< , — .........+- —_/

( (’

-15.33~ 2710—

L

o

(c)Three-viewdrawing.

Figure1.-Continued.

. .. ——.—.—. ——. —— —.— -—— -— —~ .— —..

%ln bp ]dnt0.033h thlok

NACA 2412 Profll>

Q Rivub tn mnln mar(all t’M I’IW8 ahead Of rm!n fwtl

.—

(d) Cmparison of actual wing profile with NAC!A241.2profile,

Figure 1.- Concluded.

4xNACATN~62 25

3Xhaustduct

/. —

\ / ~ edgeducts

Main ductExhaustduct= Centerduct

Blowerexit~ <*

BlowerEngineexhaust

GearboxEngin#

loEnginecoolantradiator

(a)Sketchof equipmentinstallation.

Figure2.-Equipmentinstallation.

.—_—... —— ——..— —._, _.. — -—-

Ncm

.~1 %<, ‘“,

,’ I \-‘., . .e

I i. ~— . .. . . .

L-67926(b) Leading-ei@-duct s+ructure.

Figure 2.- Conttiued.

I

—.—

,

Ui

r

(c) CloBeup of pm.mus leading

Figure 2.- Continued.

L-T02’/’2edge.

I

28 NACATN3062

1

d!!L-7’7565.l

(d)Center-ductinstallationin cabinroof.

Figure2.-Continued.

,

IJ

I

“L. “ .–— —h . . . .

‘r1’

--”’—— --—.._.,, !(e) Ri@t-mti-duct IasGtion. L-67931.1

Figure 2.- Continwd.

I

(f) Duct junctionandblower.L-70872.1

Figure 2.- Continued.

NACATN 5062 31

IF\\,

L1.,: ,i‘j1,:

k)L-7027001

Mgine-blower installation.

Figure2.- Concluded.

I

.-2

I

— — ..— — —.—— ———. —. —-. —.— .——

32 NACATN 3062.. .

-----

t’ I-,

,“,; ,; ..”. ,. .- -. - .

.

(a) Normal.L-72837

-L -. :, 5, .’., >,,?,- \.* ,-’ “.-. *’ -‘mk

. . 1.:.-. .’ --- -. —-,

-“ .. ----~1

. . Ir I

L-72838(b)Collapsed.

Figure3.- Effectof suctiononunstiffenedleadingedgewithonlyfirst2 percentofleadingedgeopen.

—

5xNACATN 3062

w

LJ

w

w

cmfigurathl

(a)M 8percent

(b)FWst 2percentopen

(c)m’st1percent‘open

(d)Sealed

(e)Centersectiononlyopen

(f) Last 1percent

x/c

0.08

.@

.01

0.

.08

.01

(d Wtboti ‘ .08sealed

a-b

O.w

.@

.@+

o

.115

.W

.548

sA’/9A

0.892

.@

.892

0

.145

.=

.627

Figurek.-Porous-leading-edgeconfigurationstested.

33

%/S*

o.081

.029

.018

0

.012

.008

.057

— —. —____ —.-. — —. -——. —

34 NACA‘IN3062

1.6

●2

o6 4 8 12 16 20

Pressuredifferenceacrossporousmaterial,Ap,lblsqft

Figure5.- Variationofappsrentvelocitythroughporousmaterialpressuredifferenceacrossporousmaterialfromgroundtests.edgeconfiguration(a) .

24

withLeading-

NACATN 3062 35

194

1.2

1.0

.0

.6

.4

.2

0

1~~~ Condition / c ‘ I stall

/IO Flight Wet /‘ -[

❑ Flight Dry / /’ I~ Ground

iWet //’f /

/K~tiated] ~A Ground Dry,.’j tren* /

/ \/

I 1/ t

/I I

/r I // f /

/ //

I /JI I

LA / / /’/ .EstinAtedaverage/

Ilocalpressure

/ ~erp,r~~,ea~gI /“edge t/ {

& //1/‘

/

/’/

;/

o 20 40 60 80 100 120

Fressuredifferencebetweenfreestreamandduct,P.- PI>~/sqM

Figure6.- Effectofrainonporosityofporousleadingedge.Leading-edgeconfiguration(a).

——___ ________ —.— —— -——...—.—

1.4

1.2

1.0

.8

.6

●4

.2

0

Figure

TEstimate

*, sec

_8

5Initiallywet >

l.ydrII

trendduring /’“engineacceleration /

d’/

/’

//

/,/

/

//

●M

0 20 40 60“ 80 100I@ SSUI% differenceacrossporousmaterial,Ap ~ lb/sqft

7.- VariationofapparentvelocimthroughpressuredifferenceacroSsporousmaterial~dLeading-edgeconfiguration(a).

porousmaterialwithtimein seconds.

—

1. Porous material drag 1.34hp2. power to reduce duct pz?essure 2. 0 hp

$. Duct losses - i. Blower losses

2

9:6: k:. Gearbox los~es .30 hp. Power for accessories

7. Total engine output M ““ ‘,.

Theoreticalaerodynsniopower )+.OL’hp

Figure 8.-Estlruateddistributionof input power for the gkhiing conditionwith rmdnnm blower at the stall. Leading-edge configuration (a).

38 NNA TN 3062

LeadhgLeading-eem Ymnf&araton

sealed llatd Power Flaps

z.4

.8

2.4

.8

Q

0 .- .0008 .Omz .0016mm 00emOlmt,cQ

o .@ .0008 .0012 .0016FlowOOetfiOlent,CQ

o❑

oA

Gll upon kml

off up

off Ik.m

0 .C@ .0008 .001.2 .0016Flow008ff10i.3nt,CQ

0 .Ood+ .0008 .Oolz .0016FlowaOefftOWlt,cQ

.

Figure9.- Variationofliftcoefficientatthestallwithfluwcoefficient. -

—

NACATN3Q62

LeadingLeading-edgeedm confluuatlonae~ed li:ted PowerFlnp,g

Q

.8

0. .000!! .Oooa .00I.2 .0016plowOOeffialent.C~.

0 .CfJd+ .0008 .Oolz .0016MOTc04fflclent,cQ

Gnup

cm DOml

off up

off Ikn’n

2.4

.8o .Oool+ .0008 .oo12

FIow ooeffioient,~

.om6

.,

Figure9.- Concluded.

o .oo@ .0008 .0012 .om6plo=ooeffialent,~

. .. +-— -—-—— ._ .——. . .. —.—— —.. —

40 NACATN3062

9

8

\

7 L

6 \

m

;5Most rearward extent

: ofporousarea2a

;bm

1!

3

2

1 , .

0 .02 .04 .06 .08 .10Chordwi.sestation,x~c

Figure10.- TheoreticalchordwisepressuredistributionovertheuppersurfaceoftheNACA2412airfoilat a liftcoefficientof1.6.

.

.

.—

6XNA.CATN 3062

Figureid..-

/Elight\

/ (a)porositydata

o 8 16 & 32Wessure differenceacrossporousmaterial,Ap, ~b/8qft

1.8 1 1 1Poweroff,flapsup,leading-edgeconfiguration(a)1 1 1

IIU-1.6 Porous

leading !e“ edge ~ghtC -.; sealed

z!% ‘wind tunnel: l~c

5

El c

i1.2

‘1

I(b)Aercdgnamicdata,

1*OI I I 1 I 1 I 1

0

Comparison

3

.001 .002 .003 .ooI#Flowcoefficient,CQ

ofresultsofflightandwind-tunnelinvestigations.

-———-— ..— —— ———.

IA12055Figure W. - &pical. frame fran tuft photographs.

,