Bengtson FOKKER DVII User manual

FokkerDVII36”
Copyright©2005‐11M.K.BengtsonAllRightsReservedRev07/11
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FOKKERDVII
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R/CScaleModelInstructions
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FokkerDVIIbyBertAyers
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CONTACTINFORMATION
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TheFokkerDVIIwasdesignedbyM.K.Bengtson
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ManufacturedandDistributedby:
BengtsonCompany
e‐mail:[email protected]m
WebSite:www.aerodromerc.com

FokkerDVII36”Page2
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Copyright©2005‐11M.K.BengtsonAllRightsReservedRev07/11
FokkerDVII
ThankyouforpurchasingtheFokkerDVIImodelfor
electricflight.AsemiscaleadaptationoftheFokkerDVII,
thismodelisdesignedtobeeasytobuildandexcitingto
fly.
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POWERSETUP
TheSpeed400motorpowersthemodelandtheMini‐
Olympus2.33:1gearboxanda10x6APCprop.Battery
powerpackcanbe8x600maHNicadsoranequivalent
weightNimh
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SPECIFICATIONS
Morethan200lasercutparts
Scale:  ~1/9
Channels: R/E/A/TorR/E/T
Wingspan: 36ʺ
WingArea: 318sqin
Weight: 25ozreadytofly
PowerSystem:Speed400,Mini‐Olympus2.33:1gearbox
Prop:  10x6
Wheels: Balsa&plywood,Neoprenefoamtires
AirfoilType:Flatbottomed,nearlyscaleshape
Cowl: Builtupbalsa
Spinner:N/A/
Decals: Availableonwebsite
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BEFORESTARTING
Anoteaboutthephotos:Thephotosweretakenofa
prototypeandthepartssuppliedmaylookslightly
differentfromthem.However,theconceptsillustrated
arethesame.RoddPerrinbuilttheprototype.
WINGS
TheDVIIhadanunusualwingprofilelookingfromthe
noseoftheaircraft.Thewingribstaperedinheight
towardsthetipandhadthetopofthewinglevel(the
bottomofthewingcurveduptogiveanapparent
dihedral).Themodel’stopwinghasthecorrecttaperin
theheightoftheribswiththetopofthewingbeing
straightandthebottomtaperingupatthetips.
Similartothebottomwing,thetopwingismadefrom
twopanelswithacentersection.
Thetrailingedgescanbesandeddownversionsofthe
templatessuppliedinthekit.Alternately,use¾”trailing
edgestockandusethetemplatesasaguidetosandthe
scallopsinthebackedge.Apieceofsandpaperwrapped
aroundasuitablecylinderorbottlemakestheperfect
sandingtool.Thismethodsavesalotonsandingtime.
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TopWing
Thetopwingcanbevirtuallybuiltupbeforeanyglue
needtobeapplied.
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TheLeftTopWing
TheplansshowthepartsforboththeR/EandR/E/A
versionofthetopwing(moredihedralintherudder/
elevatorversionanddifferentribsforwheretheailerons
aresituated).
TheaileronsfortheDVIIareonlyonthetopwingandare
relativelysimpletomake.
Apre‐cutwingtip,leadingedgesparandribsmakethe
jobeasy.
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TheLeftAileron
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WingIPStrutAttachmentPointDetail
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Copyright©2005‐11M.K.BengtsonAllRightsReservedRev07/11
ThewingIPstrutsarerecessedintoslotsintheupper
portionof1/8”ribs.Somescrap1/8”balsasandedto
matchtheribprofilereinforcestheseslots.
Withtherightandleftwingpanelsfinished,itistimeto
jointhetwoviathecentersection.
Beforejoiningthepanels,aquickcheckwiththesteel
rulertomakesureeverythingisaligned.Sightingdown
thelineofthetopspar(1/16x1/8bass)withthesteelruler
insertedintheholeforthetopspar
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CheckTopSpar
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SightingDowntheLineoftheTopSpar.
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Theaileronjoinsthewingatanangletothetrailingedge.
Thismeansthattheaileronservo,whichneedstobeat
rightanglestothedirectionofaileronmovement,also
needstobeatanangletoavoidbinding,etc.
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LowerWings
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TheLowerWing
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LowerWingSheeting
Theinnertworibbaysaretopsheetedwith1/16”balsa.
Thefinalsandingwillremovethesparextendsbeyond
theendoftherib(sodoesthesheetingforthatmatter!).
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WingsCompleted
Fuselage
Thefuselageisa1/8thbalsaforwardsectionwithabuilt
uptailarea.Thisproducesafuselagethatisbothlightand
strongandiseasytomakestraight.
The1/8thsectionismadefromtwopiecesofbalsa.They
arekeyedtoensurethatthefuselagesidesareassembled
correctly.Thisisespeciallyimportantasthecabanestrut
cutoutsarealreadyinthefuselageside.

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ForwardFuselagePre‐glue
Makesureyouallowthemtodrythoroughlybefore
movingthemfromthebuildingboard.Alightsanding
doneatthisstagewillgetridofanyjointline.A1/32”ply
doublerisnextplacedoverthemiddlesectionofthe
fuselage.
1/32”PlyDoubler
Theplansshowwherethisshouldgo,butitcanbeputin
thewrongspotifcareisnottaken.
Atthisstagealeftandrightsidearemade,somarkeach
sideappropriatelybeforecommittinganygluetothe
model.
Uselightpencillinestomarkwherethedoublerneeded
togotomakesurethatglueisnotspreadeverywhere.
Afterwaitingforthegluetotack,weightbothsidesdown
withleadshotbags(andsomeplasticwraptomakesure
theydon’tsticktogether)forthegluetodry.
Oncethefuselagesidesaredry,theformerscanbe
attachedtooneside.
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RearFormerisBeingGluedtoOneSide
Similarly,thefrontformerisgluedtotherightside.
NoteRoddʹsextensiveuseofweightsandsquarestomake
sureeverythingisalignednicely
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Oncetheglueisniceanddry,thetwosidesarebrought
together.
Addthe1/32”plycabanestrutmountingreinforcements
insidethefuselage.

1/32”PlywoodCabaneStrutMountingReinforcements

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RearFuselageConstructionDetail
Therearfuselageismadefrom1/8thsquarebalsasticks.
TheDVIIshouldhavethelongeronsmadefromhard
balsa(butnotbulletproofbalsa!).
Thefirstsideisbuiltovertheplan,withthesecondside
beingbuiltoverthetopofittogivetwoidenticalsides.
Bitsofcoveringbackingpreventthesidessticking.
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ScrapBalsatoHoldthe1/8thSquareFlattotheBuildingBoard
Roddusedsomescrapbalsatoholdthe1/8thsquareflat
tothebuildingboardsohedidnothavetopinthrough
thelongeronsandweakenthem.
Witheachsidealignedtotheplan,thecrossmemberscan
starttobegluedintoplace.
Whencuttingthecrossmembers,cuttwoatatimesothey
willbeidentical.Thiswaytheyarebothright.
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RearFuselage
Theblockofbalsaatthetailisforthelandingskid.
Addasmallbitif1/8thsquarebalsa,suitablytaperedtofit
betweenthetwoendpostsofthefuselage,tomakethe
rearjointniceandfirm.
Asthereisamajorchangeintaperintherearfuselagejust
underthetailplane,smallcutsweremadeintotheinside
ofthelongeronswherethechangeintaperislocated.Bits
of1/8thsquarebalsasupportsthejoint.
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MotorMount
Insertthemotormountbeforethefrontofthemodel
becomestoostifftoallowittobepoppedintoplace.The
motormountispre‐cutforaS400Mini‐Olympuswith
somesidethrustalsobuiltin.Makesureitgoesintogive
rightthrust.Theparthasmarkedwhichwaygoesup.
Themotormounthastwowingsoneachside,whichfit
intocorrespondingslotsinthefuselage.
Thecowlsupportcrossmemberisgluedintoplaceafter
themotormountisinstalled.
Withthefrontfuselageessentiallycompleteandtherear
fuselagecomplete,itisnowtimetobringthetwo
together.
Atthisstage,donotaddanyoftheupperformerstothe
frontfuselagetomakeiteasiertosetthingsupflat.
Thefrontfuselageisweighteddowntothebuildingboard
andtherearfuselagealignedintotheslots.
UnlikesomeBritishaircraft,theDVIIdoesnothavea
straighttoplongeron.Bitsfromaroundtheworkshopare
usedtopropuptherearfuselagetogettherightchanges
inslope.Checkthatthestructureissquare.
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RearFuselageDetail
TIP:Putlittlemarksalongthecenterlineofformers,etc
whichwillsignificantlyhelpthejoiningprocess.
Thesecrettoastraightfuselageistoholdoneendfirmly
whileallowingtheotherendto‘float’alittle.Thisensures
thatthepartsdofitintoplacewithouthavingtobeforced
tofit.
Thetopfuselageformersweregluedintoplaceandalso
downtherearfuselagetosupporttheturtledeck.
Roddusedpapertomakeupatemplatetoavoidwasting
balsa.
Thetemplatewasmadeslightlyoverlong,withoneend
15mmwideandtheotherexpandingto86mmwherethe
rearfuselageformerwaslocated.Anyoverhangwas
sandedoffwhentheturtledeckwasgluedtothefuselage.


FuselageTemplate
Thecowlneedstobeconstructednext.
Thecowlismadefromthreepiecesofbalsa–two1/4”
andone1/8”Thethinonegoesinthemiddle.
Thegearboxmustsitdownonthemotormountingplate,
sorelievethefrontbracealittleandgougeoutasmall
groveinthenosehatch.

GearboxDetail

Gearboxinplace

Cowl
Theradiatorwasthentackgluedintoplaceonthenose
androughlysandedtoshapetomatchtheDVIIdrawings.
Lookingfromthetop,theradiatorshouldhaveashape
approximatelylikeaflatbottom‘v’.

Rough‐SandedNosefromtheSide

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Toprovidealittlesupport,Roddgluedsomescrapbalsa
intothethinnedareasforadditionalsupport.

BackofCowl,
Note:C1wasincorrectlyplacedupsidedown.
Roddmadehiscowlremovable,althoughthisisnot
absolutelynecessary,itdoesmakeservicingthemotor
easier.PairedNeomagnetsmakeexcellentattachment
holdsforthisapplication.



RadiatorMeshTemplateDetail
Forthemeshcoveringthefrontoftheradiator,thisis
shownontheplansassomewire‐doorscreen.
Tohelpwiththefittingprocess,Roddcutatemplatefor
theholeinthefrontfromsomescrapcardboard

RadiatorMeshDetail
Abitofmeshwascutroughly3–5mmoversizeandthen
bentaroundtheformertogivearoughshape.
Roddusedpull‐pullcontrolsforthetailfeathers,sohe
addedsomesupportsforthewireswheretheyexitthe
fuselage.Hesupportedthewiresusingsomelightbalsaat
theexitpointswiththewiresroutedthroughsmall
aluminumtubestostopthemeatingthroughthefuselage
everytimetheymoved.
TubesMountedandSanded/FiledFlushwiththeSurface
Thepairoftubesisfortheelevatorwhilethesingletubeis
fortherudder.Makesuretoroughupthesurfaceofthe
tubesbeforeyouCAtheminotherwisetheywillpullout.
Thetubeshavebeenbentroughlyintoposition,withthe
finalanglesofthetubeshavingtowaituntiltheservos
andwiresinareinplace.


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
FrontofFuselage
Theenginesitsonanotherbitof1/16”sheetthatisslightly
lowered(toroughlythetopofthefuselagesides).Of
course,thismustbefittedbeforeyouaddthetop
sheeting.
TailSurfaces
Thesestructuresarebuiltfromsuppliedlasercutparts
andabitofbuildersuppliedstripstock.

HorizontalStabilizerandElevator
Useslightlyharderbalsaforthetrailingedgeofthe
horizontalstabilizerasthiswouldactasabitofaspar.

Rudder

VerticalStabilizer
Therudderismostlyfromthelasercutsheet,againwith
stripwoodsuppliedbythebuilder.
WHEELS
Gluingtheplysidesonthe3/8”balsacoremakesthebasis
forthewheels.Usethebrasshubforalignment.Epoxythe
hubsinplaceandaddasufficientamountofepoxy
aroundthebaseofthehubtoreinforcetheconnectionof
thehubtotheply.Plywoodreinforcinghubsareprovided
thataretoslipoverthebrasstubingasshown.Next,CA
gluetheneoprenecordingtogethertofroma“tire”.Use
thinCAsparinglyastheCAbondsveryaggressivelyto
therubber.PresstheCAwettedendstogetherforan
instantbond.Thebestwaytoaligntheendsistoglue
themwhiletheyareinplaceonthewheel.Thenattachthe
tirestothewheelsandCAinplace.AthinbeadofCA
aroundtherimmakesforasecuretire.
Paperconesarecutout.Useaballpointpentoscoreeach
lineonthebacktomakeanimpressionof“spokes”Itis
helpfultodothisoperationonapapertabletsothatthe
penmakesagoodcrease.Foldthepaperalongthecrease
linestoexaggeratetheraisedlines.Oneofthesections
formingawedgeiscutout.Makecutstothecenterofthe
circlealongapairofthespokes.Closethepapercutoutto
formaconeandtapethejointinsidethecone.
Theinsideconesmaynowbeattachedtothewheels.The
outsideconesmaybeattachedatthispointifwheel
collarsaretobeused.Alternatively,afterinstallingthe
wheelsonthelandinggear,awashermaybesolderedto
holdthewheelinplaceandthentheconeisattached.This
methodmakesaverynicescaleappearance.

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CompletedWheel
Thewingstrutsaremadefrom¼x1/8spruce/bass/etc.
Cutoutthethreesectionsaccuratelytotheplansandthen
gluedthemtogetherovertheplans.
Makesurethatbothstrutsarethesame.
Aftereverythingisaligned, these need to be sanded
into roughly an airfoil shape.

IPStrutConstructionDetail
Thecabanesareaddedduringassembly.Thebottom
wingsareattachedfirst,withoutthelandinggear.Thetop
wingsarethenattachedusingtheIPstruts.Thisusually
putsthetopwingprettyclosetothecorrectalignment.An
alignmentjigmadefromfoamboardholdsthetopwing
inalignment.Thejigisa~rectangularpiece tofitbetween
thetopofthefuseandbottomofthewing.Itistaken
directlyfromthesideview.Thedeviationfrom
rectangularisduetothetopwingʹsincidence.Thenlength
ofthecabanesisthenadjustedtofitthemodel.Eachpart
issandedandmatchedinlengthtotheoppositepart.
Epoxythepartsinplace.
Theundercarriageismadefromthreebitsof1/16”wireto
theshapesshownontheplan.
Withabitofplanningandsomecarefulmeasuring,itis
nottoohardtogetsomesymmetricallybentbitsofwire
readytobesolderedtogether.
Tohelpwiththesoldering,Roddmadeanundercarriage‐
solderingjig.
Bymeasuringfromtheplansthespacingandalignmentof
thevariousbits,theundercarriageisclampedtothejig
andthejointscleanedwiththewirebushontheDremel.
Withthejointsniceandshiny,abitofwirebindsthe
joints.Solderusingplentyofheat.Alternatemethod:lash
thepartstogetherwithKevlarthreadandCAglue.Finish
thejobwithepoxy.

UndercarriageConstructionJig


UndercarriageWingParts
AveryprominentfeatureoftheDVIIwasthe
undercarriagewing.
Theplandesignedthewingtobebuiltoverthewire
undercarriage,sothereareslotsinthebottomoftheribs
toallowtheaxletopassthrough.Thetopslotsarefora

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1/8”squarespar.Thebottomofthewingis1/8”balsa.
Herearethebasicundercarriagewingparts.Alignment
linesfortheribshavebeenmarkedonthebottomplate.

CompletedUndercarriageReadyforSandingandCovering
INSTALLINGTHERADIOCONTROLGEAR
AileronServos
Aileronservosaremountedinwingandattachedwith
shortthreadedrodstotheailerons.Note:Usea“Y”
wiringharnessconnectortowiretheservostoasingle
radioconnection.
BatteryTray
Afteralltheabovehasbeenplaced,mountthebattery
traymadefrom1/8”balsaandusethebatterypositionto
balancethemodelasshownontheplan.

ASSEMBLY
Withthemodelflatonthebench,usethelocatingdowels
toassistwithaligningthebottomwingpanelstothe
fuselageandepoxyinplace.Thecabaneandinterplane
strutsareaddednextfollowedbythetopwing.The
alignmentofthetopwingistobecheckedbutmainlypre‐
determinedbythesestructures.
FittingtheTailSurfaces
Glueonthetailsurfacesnextmakingsurethattheyare
straightandtrue.Thereisaslotinthehorizontalstabilizer
forthetabontheverticalstabilizer.Ifpushrodstyle
controlsareused,cutandbendtherodsfirstwiththe
controlhornsdryfittedinplace.Thenwhentheservosare
centered,gluethehornsinplace.

ModelintheBones
COVERING
Almostanylightweight‐coveringmediumwillbefine,but
avoidanythingthatislikelytowarpthestructure.
Althoughpaintshouldbekepttoaminimuminorderto
saveweight,normalhobbyenamelswilltakewellto
Litespan.
Ifyouintendtoaddextradetailtoyourmodel,bevery
carefulnottooverdothings.Alittledetailcanvery
quicklyaddalotofweight.
Downloadabledecaloutlinesareon‐lineat
http://www.aerodromerc.com/decals.htm
ThemodelshouldROGonpavementorhardsurfaces.On
grass,themodelmayrequirehandlaunching.Becareful
thatyourhandorfingersdonotcatchonthelower
rigging.Launchfirmlyandlevel.Whilethetailsurfaces
aresmall,theyshouldnotneedexcessivethrows.Letthe
modelgainaltitudeslowlyofftherunway.Applyingtoo
muchupelevatoratslowspeedsasksforastall.Make
yourturnsgentlyastightturnsrisktipstallinginany
model.Don’texpecttheelevatortomakethemodelclimb.
Thinkoftheelevatorasadevicetochangetheattitudeof
themodel.Thewingandairspeedultimatelymakethe
modelclimb.Oftendownelevatorappliedatstallingcan
avoidamajorcrash.Themostimportantdetailsfor
properflightoperationsare:
1.CGlocation.Tail‐heavymodelsneverflywellor
atall.
2.Downandrightthrust
3.Straightandnon‐warpedwings.
CONTACTINFORMATION
Distributedby:
BengtsonCompany
e‐mail:[email protected]
WebSite:www.aerdromerc.com