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POURENEWduCiel

ThemagazineforenthusiastsofHenriMignetsdesigns

IssueNo.40

1 5BLMCanard

10CosandeyMoreBLM8

Part103FlyingFleas

FourthQuarter,2010 ...betterlatethannever!

BLMCanardbyRaymondBaudouinThefutureFlyingFlea?

FromvarioustextswrittenbyRaymondBaudouin,collectedandtranslatedbyPaulPontoiswiththeprecioushelpof AlainBerland

ComparisonbyRaymondBaudouinbetweentheHM293Grunberg

andthePou-CanardBaudouinBLM

4 Axel,RaymondandMichel

Forbothaircraft,thefrontwingpivotsarounditsspanwiseaxis,whichchangesitsincidenceangleandtherearwingisfastenedto

thefuselagewithapredeterminedincidenceangle.

AccordingtoRB,theratiobetweentheareaofthefrontwingandtheareaoftherearwingdeterminesthelocationofthecenterof

gravity.

ExperiencefrommodelsandflighttestsonthePou-Canarddeterminedtheverticalandhorizontaldistancesbetweenthewings.

Inthisstudy,RB,foreaseofunderstanding,considerstheangleformedbythe2virtuallinesextendingthechordsofthefrontand

rearwings.

Ifthe2linesareparallel,theangle(measuredunderthewings)isconsideredasbeing180.

IftheVformedbythe2linesispositive(asanormaluprightV),theangleismorethan180.WewillcallthisVinterincidence.(Int-Conthedrawings)

IftheVformedbythe2linesisnegative(asaninvertedV),theangleislessthan180.

Becauseofthewingareasratio,eachmodelofflyingfleahasaspecificlocationoftheGC. -->

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Wingsareas:Front:6.72sqmRear:5.09sqm(areasratio:1.3)Chordforeachwing:1.2mHorizontalgapbetweenwings:0Thelongerwingisthefrontwing. TheareasratiodeterminestheCG(centerofgravity)locationat25%ofthetotalchord(distancebetweenfrontwingleadingedgeandrearwingtrailingedge). Theinterincidenceisnegativeat177t-i:180-6(incidencerearwing)+3(incidencefrontwing).As,forafrontwingincidenceof-2,theliftisequaltozero,theremustbeastoptopreventthewingreachinganegativeincidence.1/-Innormallevelflight,thestickisvertical,withoutpushingorpullinginthehand.

2/-Ifthepilotincreasesthespeedandpushesthestickforwardtillthefrontwingincidenceis0(againstthestop),Theinterincidenceisnegativeat174t-i:180-6+0.Thestickpushesrearwardinthepilot'shandandtrendstowardscomingbacktothepreviousposition(+3incidencefrontwing).

3/-Iftheclassicalflyingfleaistailheavy(b-e:28%totalchord),withthesameincidences,

Atcruisespeed,butstillmoreatincreasedspeed,thestickwillpushforwardinthepilot'shandtothestop.Butiftherewerenostopat0incidenceandifthepilotdoesnotholdthestick,itwillcrossthepointofzeroliftforthefrontwingandtheflyingfleawillenterintoanirreversibledive.

- ForRB'sPou-Canard(BLM).

Wingsareas:Front:4.3sqmrear:6.94sqm.(areasratio:1.6)Chordforeachwing:1.2m.Horizontalgap:0.35m.Theshorterwingisthefrontwing.TheareasratiodeterminestheCGlocationat34%ofthetotalchord. Theinterincidenceispositiveat181,t-i180-2(rearwingincidence)+3(frontwingincidence).1/-Innormallevelflight,thestickisvertical,withoutpushingorpullinginthepilot'shand.

RBpointsoutthat,duetothis181interincidenceangle,therangeoflongitudinalstabilityis4higherthanfortheconventionalflyingflea(181177),whichisimportant,aswewillsee,whentheaircraftistailheavy.

2/-Ifthepilotincreasesthespeedandpushesthestickforwardtillthefrontwingincidenceis0(againstthestop),theinterincidenceis178t-i:180-2.

-

redesignedinthe80'sbyRodolpheGrunberg.

Asanexample,fortheclassicalflyingflea,RBtakestheHM293

Croisirestabilise=cruisespeed

Vitessemajore=increasedspeed

Vitessemajore=increasedspeedPortancenulle=ZeroliftSansbute=Nostop

Croisirestabilise=cruisespeed

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(BLMcanardcont.)

Thestickpushesrearwardinthepilot'shand

andtrendstowardscomingbacktothepreviousposition(+3incidencefrontwing).

3/-IftheBLMistailheavy(b-e: About37%totalchord),withthesameincidences,atcruisespeedandevenathigherspeed,thestickbeingpushedbythepilotagainstthestop,itwilltrendtowardscomingbackbyitselftothevertical(neutralpoint).Iftherewerenostop,thestickwouldnothaveanytendencytogoforward.

Remark: InthenextissuesofPou-Renew,wewillseetheimportancegivenbyRaymondBaudouintothehorizontalandvertical

distancesbetweenthetwowingsandhowhecalculatestheCGlocationinrelationwiththewings'areasandweights.

...forthoseinterestedindetails,youmightliketo

writetohim(inFrench,please)at:

RaymondBaudouin,QuartierlesCharignons,Peyrus26120,France

M.

CongratulationsAudreyandWilliam !ThanksforsharingMatt---

Sun,Jun20,2010HappyFathersday!

Lookwhatmytwokids Audrey(10)and William(6)madeforFathersday!Matt

MattNaivasartistkidsandfutureFlyingFleaers

Vitessemajore=increasedspeed

Vitessemajore=increasedspeedPortancenulle=Zerolift

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AboutAxel,RaymondandMichelonCanardFleas

WhilegoingoverfortheumteenthtimeRaymond`sgraphicsbegantomakealittlemoresensetome!

BasicallyheisgraphicallyshowingtherelativedisplacementoftheCGandtheFGondifferentconfigurationsandflightconditions.QuiteclearlyshowingthatinsomeconditionstheCGeithercoincidesorevenisbehindtheFG,which,aswewellknow,makesforalongitudinallyunstableaircraft.

Michel,withhiswideverticalandhorizontalwing-gapsmanagedtonotonlygetawaywithveryaftCGs,butasafringebenefit,stumbledacrossthefactthatatcertaingaps,theairflowovertheentiremachinebecamelaminar,withinmostflightconditions. Thiswasagreatadvantagebecauseitallowedbothgreatercruisespeedsandalowerstallspeed.

Axel,whoisdearlymissed,gotenthusedbyMichelsdiscovery,andstartedstudyingtherangeofwherethisphenomenonapplied,usingveryadvancedflightanalysiscomputerprograms.Inhiscase,he

discoveredthattherangewasquiteample.Iquotepartofoneofhismails:

Axelcarriedonhisresearcheventestingshorterfrontwingspans.

>>>InqualifyingMichel'sempiricalresultsfromhis'France'days,whereheused80cmEhand70cmEvIfoundthatthereisasolidrelationshiptolaminarflowatequalentreplans.So,thereforerecommend65/65,70/70,80/80orwhateveryouchoose,howeverthegreatertheentreplanthebetteruptoapointandmorespecificallyitrelatestotheverticaltokeepasmoothflow.

AsMicheldemonstrated80h/70vintufttestsasaworkinglaminarentreplan,(withcertainaerofoils-itmakesadifference)Imodeledthisplanandfoundwithvariousprofilesthatlaminarlowdrag

performancecanbehadatsmallerEhiftheEvwasatleast80cm.Asamatteroffact,Igotallthewaydownto50cmEhbeforeit

wentturbulent. WiththeEhat80cm,theEvbecameturbulentatabout65cm.Verticalentreplanismostimportantinthed'Escathaformula.Itisliterallywhateveryonehasignoredfordecades

becausechangesinEvhavelittleeffectwhileturbulent.

Inthefinalanalysis,Ifoundthatstartingat90cm/90cmwithanyofthemostusedaerofoilsonPou'sthattheyremainedinlaminarflowallthewaydowntoabout20cm/20cm.Ofcoursebelow50or60cmitisn'tofpracticalusebutinallcasesitdidperformcorrectlyfromhighspeedjustbeforecenterofpressurebouncesoffintoinfinity,andintheotherdirectionveryslowspeeddeepmush. Thiswaswithequalspans,equalchords. Whenusingunequalspansorinadditionunequalchordsturbulencewasdifficulttoavoidbelow50cm.

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CONTRIBUTIONLTUDEET AURGLAGEDES ARONEFSDEH.MIGNET

par LouisCosandey,technicien.PilotebrevetCsur planeur Pou-du-Ciel

(CONTRIBUTION TO THESTUDY AND TOTHE AJUSTEMENT OF THEH.MIGNET

AIRCRAFT)TranslationbyPaulPontois

(continued)

ManyamateursareconvincedthattheNACA

23012airfoilmadetheFlyingFleastablein

everysituationofflight.Thisiswrong,but,on

theotherhand,thefactthatthecenterofLift

ofthisairfoilispracticallyinvariablemadethe

elevatorcontrolmorestable,theleverarm

beingpracticallyconstant.

Thetwowingsaretooclosetoeachotherto

workindependently.The2airfoilsinlinehave

tobeconsideredasasingleone,theshape

ofwhichchangesaswantedbythepilot.

Mostofthetime,theincidenceoftherear

wingisbiggerthantheincidenceofthefront

wingandtheresultingairfoilishollow,withaslotinthemiddle.

Thisslotisveryimportant,asitgivestheaircraft

atremendousstabilitywhenflyingathigh

angleofattack

Thisstabilitydecreasesastheangleofattack

decreases.

Todecreasetheangleofattackwepushon

thestickand,consequently,weincreasethe

negativeinterincidencebetweenthetwo

wings.Theairfoilformedbythetwowingsbecomes

stillmoreconcave.Weareclosetothe

instabilityzoneand,ifthelocationofthe

centerofgravityisnotproper,theplanecould

tumbleonitsback.

Wehavetoadmitthattheoldsharpnosed

airfoiloftheHM14wasmorestableinadive

thattheNACA23012.

Toillustratetheabove,hereunderaretwo

curvesofstabilityshowingtheincidenceof

thefrontwingintheairflow,inrespecttothe

positionofthestick

ThefirstcurvereferstotheoldHM14sharp

nosedairfoil,withnooverlappingofthefront

wingovertherearwing.,locationofthecenter

ofgravity:46.5%ofthefrontwingchord(65cm

fromtheleadingedge)

ThesecondcurvereferstoaHM210model,

airfoil:NACA23012withtheregulartrailing

edge.intervalbetweenthetwowings10cm.,

locationofthecenterofgravity:48%ofthe

frontwingchord.

Manchepouss=stickfrontwardManchetir=StickbackwardIncidencedel'aileavantsurlatrajectoire=Frontwingincidencewithrespecttotheflightpath.Sansborddefuiterelev=withregulartrailingedge

FortheHM14,wenoticethattheslopeofthecurveismoreorlesssteady.Foronepositionof

thestick,wehaveone(andonlyone)attitude

AIRFOILS ANDSTABILITY

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(Cosandeycont.)

oftheplane.

Fortheothercurve,correspondingtothe

NACA23012airfoil,wenoticethat,atlow

incidence,asmallmovementofthestick

givesalargevariationofattitudeand,whichis

stillmoreworrying,foraninterincidenceof-3

degrees,theaircraftcouldtake2different

attitudes,+3degrees(pointA)or-6degrees

(pointB).Wearerightintheinstabilityzone.

We,ofcourse,tookthisexampleforthe

purposeinhandandwenowaregoingtosee

howtoexplainthisparadox.

Idobelievethatthelocationofthecenterof

gravity,whichseemstobealmostidenticalfor

bothaircraft,especiallyifwetakeinto

considerationthedistanceof10cmbetween

thetwoNACA23012wings,isnotreally

identical.Thecenterofliftofthe23012is

situatedat26%ofthewingchordwhilethe

centerofliftoftheold1934Mignetairfoilis

situatedat30%minimum.Thereforeifwewantthetwoaircrafttohavethesame

aerodynamicreaction,thecenterofgravity

locationoftheHM210(23012airfoil)should

bemovedforwardtobelocatedatmaybe

44%ofthechordinplaceof48%.Thecurve

wouldcertainlybedifferentandmorestable.

Whatshouldwethinkofthelocationofthe

centerofgravityrecommendedbyMignetfor

theHM293,muchmorebackward?

First,wehavetotakeintoconsiderationthe

lifteduptrailingedgeoftherearwingwhich

makestheplaneautostable,especiallyatlow

flightangles.Then,wehavetotrustMignet

andassumethatthenumerousprototypeshe

builtbenefitedfromtheexperienceofthe

varioustestsmadeintunnelandinflight.

That'swhywehavetocloselyrespectthe

plans.

Foraninterwing=0,thecenterofgravityoftheHM293mustbesituatedat62cmfrom

theleadingedge.Undernormalflight

conditions,Ibelievethatitshouldneverbe

morebackwardnottobecomeunstable,whichisunpleasantathighspeed.

Ifthecenterofgravitylocationisatmorethan

60%ofthefrontwingchord.Insomecases,

theelevatorcontrolwon'tbeefficientenough

torecover.(accordingtothepitchingcurves

drawnupbytheLillewindtunnel.)

Inthebooklet#2page24,wecanreadthat

theHM293hastobebalancedbetween65

and70%.Ihopefortheamateursthatthey

meantbetween65and70centimeters,ifnot

theyaregoingtobeinbigtrouble.

However,wehavetoremindthereaderthatthe

horizontalinterwinghasastabilizingaction.

Forinstance,foraHM293whichhasthe

followingcharacteristics:

Frontwingspan:5.50m.

Rearwingspan:4.20

Rearwingtrailingedgeturnedup,

ifthehorizontalinterwingis+10cm,thecenter

ofgravitycanbelocatedat65cmfromtheleadingedge,butiftheinterwingis20cmfrom

theleadingedge,itcanbelocatedat68cm

fromtheleadingedge.

Diagram#8givesusagoodideaofthe

characteristicsofthe3airfoilsusedfortheflying

Fleas.

These3airfoilsare:

Thesharpedgedairfoilasperthe1934book.

Thenewairfoilasperthe1936edition.TheNACA23012.

Unfortunately,IcouldnotgettheCxcurvefor

the1934airfoil.

These3polarcurveshavebeencalculatedfor

thefrontwingonly,wingaspectratio:5.

Astheexperimentsmayhavebeendonein

differenttunnelsandfordifferentReynold

numbers,theresultsmustbetakenwithall

reserve.

TheoldHM1934airfoildoesnotbehavetoo

badly,ifweexceptthatthecenterofliftis

knowntobevagrant.Thelossofliftwhenthe

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(Cosandeycont.)

angleofattackincreasesseemstobe

progressive.

TheairfoilHM1936seemstobeexcellent.Its

centerofliftmoveverylittle.(Thispolarcurve

waskindlypassedontousbyHenriMignet)

Weshouldnotbetoosurprisedofthegeneral

valueofthemaximumCz.

Forthe23012.Weonlyreach100Cz=116,

becauseofthewingaspectratioequalto5

andofthenumberofReynoldsequalto604000,closetowhatwasgivenbytheLillewind

tunnelstudies.

Itactuallyhappensthat,whenthenumberof

Reynoldsincreases,thepolarcurveimprovesin

thesensethatthemaximumCzincreasesand

thattheminimumCxdecreases.COSANDEYENDSHERE

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FlyingFleasthatmightbeeligibleforFARPart103

(andsomemightevenfitundertheunder70Kgrequiredinsomecountries)

ThemostobviouscandidatewouldbetheButterflyat63Kgemptyweightand,notveryconvincingly,footlaunchable,aswell.Sadly,forthetimebeing,itisnotavailableanymoreinitskitformyet,withalotofluck,onejustmightbeabletotraceonedowninFranceorBelgium. Thatweknowof,thereisalsooneplusacoupleoffuselageframesin

existenceintheU.S.(alittleinvestigatingmightlocatewhohasthemandifheiswillingtopartwiththem).

Alternatively,onecouldattemptbuildingone.ThiswouldrequireobtainingtheplansfromGuyFrancoisinBrussels(Tel+320486939234)ButterflyIIisapop-riveted2024 Aluframe,meanwhiletheButterflyIIIsportsawelded Alualloyframe.Eachwiththeirownlevelofdifficulty

andskillrequirements.Thewingsusethermoformedplasticribs,whichforsomemightmeananaddeddifficulty.Maybetheycouldbereplacedwith AluorStyroribs.

Thenext,maybepossible,butnottoosureifitwillmeetthemaxemptyweight,couldbetheBifly,whichbasicallyisatractorandfuselagedButterfly.Nomorekitsaremadeyetonemightbeabletotraceonedown. TherewerequiteafewbuiltinFrance.

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-HM-293(mono-seater)redesignedbyRodolpheGRUNBERG. TheplanswhichtriggeredtherenewaloftheFleamovementinEurope.

22plans+brochureinEnglish+hardwareCDforlasercutting.Including Trigearoptionsetofdrawingsandmuchmore=150US$

-HM-360(mono-seater)andHM-380(two-seater)ThelastamateurbuiltplansdesignedbyHenriMignet,updatedbyhissonPierre.A jewelofwoodandfabricconstruction.22plansinEnglish=160US$Rearendbracketsfortrigearversion:

4plans=10US$

-AVIONNETTENewdesignbyPaulFournierfromtheHM-8book. TheHM-8wasthelastMignetcreationbeforethePou-du-Ciel.Abouttwohundredswerebuilt.24bilingualplans+

constructionphotographs=130US$

Allpricesshipping&Handlingincluded.Quickdelivery.Payment:Checkormoneyorder.

PaulPONTOIS1890rangdeschutesSTE-URSULE(Qubec)J0K3M0CANADA

Ph:8192283159Email:paulpontois@infoteck.qc.ca

AttentionEnglishspeakingbuilders!!

TranslatedintoEnglish

WECANHELP YOUGETTING

FRENCHMIGNETPLANS

(FFPart103cont.)

Nextinline,andinthiscasereadilyavailableoff

theshelf,wouldbethePouchelIILight,whichwasspecificalydesignedbyDanielDalbytomeetthePart103requirements.

Http://www.pouchel.com/english/index_eng.php?p=accueil_eng.htm

IseenoreasonwhyaPouchelLightcouldnotbemorphedintoaButterfly.Whatismore,one

couldusean AluladderasonGaryGowersLaBamba,fortheframe.

So,whataboutwood?Notonlyisitpossible,butithasbeendone.PracticallyalltheMignetPousareveryoverdimensioned,so,forexample, YvesSegonds,afterverycarefulstudyandre-engineering,managedtobuildasafe94KgHM293.

Onthesamelines,MicheldEscathahas

producedadesigntomeetthePart103requirements.Sadly,wehavenotseenanyexamplesinflight,sofirst,someadventuroustestpilotwouldhavetobuildone.

Charlie

PS:Shouldanyonehavesuggestionsforenlargingthislist,pleasefeelfreetodoso

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WENEEDYOURHELPTOKEEPPOURENEWGOING!

WRITETOUS!SENDUSARTICLES!

POURENEW10 Quarter,2010 Fourth

Fornow,pleasemailyourcontributionsto:PaulPontoisorCharlieCrawley

RaymondtaxiinghisPoucanardAftercarefulstudy,heswitchedtherearwingforthefrontoneonhiskitBifly

andtheresultwasanincrediblystableandwellbehavedcraft

ImportantNotice: DesignsproposedonPouRenewarestrictlytheresponsibilityofthedesignersandnotofPouRenew.Potentialbuildersarestronglyrecommendedtoresearchthedesignanditsbackgroundbeforecarryingon....Itisyourneckthatyouarerisking!

TheFuturePou?Baudouins

POUCANARDCanalsobeseenat:http://www.flyingflea.com.arunderButterfly>CanardFlea

Duetothelackofcontributionsandarticles,weareforcedtosuspend

PouRenewonaquarterlybasis.

Asfromnowon,itwillbepublishedassoonaswereceivefromyouflying

flea-ersenoughinformationsoastofillatleasteightpages.

Itisyourmagazineguys...sopleasestartsendingarticlessowemaykeeponpublishing!