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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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(BLMcanardcont.)
POURENEW2FourthQuarter,2010
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.
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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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POURENEW4FourthQuarter,2010
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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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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POURENEW8 Quarter,2010 Fourth
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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POURENEW9 Quarter,2010 Fourth
-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:[email protected]
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!