Bengtson Company Fokker Dr.I 35" User manual

FokkerDr.I35”
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13

FokkerDr.I35”


R/CScaleModelInstructions






CONTACTINFORMATION
DesignedbyM.K.Bengtson




ManufacturedandDistributedby:
BengtsonCompany
e‐mail:[email protected]
WebSite:www.aerodromerc.com

FokkerDr.I35”Page1
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13
FokkerDr.I

ThankyouforpurchasingtheFokkerDr.Imodelfor
electricflight.
THEMODEL


FinishedModelbyJasonHaslam
AsemiscaleadaptationoftheFokkerDr.I,thismodelis
designedtobeeasytobuildandexcitingtofly.Themost
significantchangefromscalewasthattheairfoilswere
madeflatbottomed.
POWERSETUP
TheAXI2217/20brushlessoutrunnerand11x6or12x6
proppowersthemodel.

SPECIFICATIONS
Morethan230lasercutparts
Scale:  1/8
Channels: R/E/A/T
Wingspan: 35ʺ
WingArea: 415sqin
Weight: 33oz
PowerSystem:AXI2217/20brushlessoutrunner
Prop:  12x6
Wheels: Balsa&plywood,Neoprenefoamtires
AirfoilType: Flat‐bottomed
Cowl:  Builtupbalsaandplywood
Spinner:N/A
Covering: Litespan,Polyspan
Decals: Availableonwebsite
BUILDINGTHEMODEL
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.
JohnBoeckbuilttheFokkerDr.Iprototype.

COWLING
BeginconstructionofthecowlbygluingC1andC2toa
stripof1/32”plywiththegrainoftheplywoodrunning
theshortway.Aftertheassemblyissecure,trimoffthe
bottomendsofC2asindicatedontheplan.GluetwoC3ʹs
togetherwithC4andgluethisassemblytotheC1/C2
assemblyandsandtoshape.

WINGS
WingConstruction
Pindown,overtheplan,thepre‐cuttrailingedge
plywood,sparsandwingtip,gluingasrequired.Addthe
leadingedgestock.Sandtheleadingedgestocktobe
roundedandmeettheribs.Themiddlewingsparsareto
beleftextendingasshownontheplans.Thesparsserve
inthealignmentofthemiddlewingstothefuselage.The
bottomwinghalvesarebuiltwithsparsconnectingthem
overtheplan.Keepthembottomwinginonepiecefor
strength.
TopWingConstructionDetail
TheAileronsaredrivenbyinwingservos.Theailerons
areformedfromalasercutsheetofbalsaandreinforced
withsmallriblets.IPmountsarebuiltfromtwobalsa
sideribsandtwoinnerhalfribs,makingaslotfortheply
IPstrutsprovided.
Scallopingispre‐setbythetopandbottomplytrailing
edgepartssupplied.



FokkerDr.I35”Page2
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13
TheLeadingEdgeoftheAileron
Theleadingedgeoftheaileronisroundedoverwith
sandpapertomaketheaileronmovablewithaminimum
gap.Thetrailingedgeofthewinginthatsectionisleft
flat.
FUSELAGECONSTRUCTION
Thefuselageisbuiltastwoseparateboxstructures,the
frontbalsasheetandplyareaandtherearbuiltup
section,whicharethenjoinedovertheplan.Thissystem
notonlykeepseachstagesimple,butitalsohelpsto
ensureastraightfuselage.
FuselageConstructionDetail
BuildingoftherearoftheFuselage
Beginbybuildingtworearfuselageframesovertheplan
andallowtodry.Selecthardbalsaorbasswoodforthe
longerons.Jointhetwoframesovertheplanwithcross
bracesandthetailskidmount.Check,checkandcheck
againthatthisandALLotherstructuresremainperfectly
straightandsquare.
BuildingofthefrontoftheFuselage
Thefronthalfofthefuselageisaboxstructuremadefrom
1/8”balsaandplywood.Assemblethebalsasidesfrom
thetwolasercutpieces.Addthe1/32”plywooddoubler
totheinsidesurfaces.Usingtheplanasaguide,buildthe
fuselageoverthetopviewaddingthesidestotheF1and
F3formers.Whensecure,removefromplanandaddthe
basswoodcrosspiecesandFormerF3a.Addthe
undercarriagemountsF1CandF1D.

Thetopdeckformersareaddedandtheturtledeckingis
gluedinplace.
1/16thBalsasheetingcoversthefront/topofthefuselage
betweenformersF1andF2.Theareaaftofthisisdealt
withlaterinthismanual.

MOTORMOUNT/DUMMYENGINE
Itemsneededtofinishthemotormount:
3–2‐56x2”machinescrews
HeavyCardStockpaper
String
1/32”musicwire,forpushrods
Themotorthatwillpowerthismodel
Findthetwo1/16”plywoodmotormountsplates.
Comparethemountingpatternontheplatetoyour
motor.Adjusttheholesifnecessary.Laminatethetwo
platestogether.Findthe83/16”balsamotorcorepieces.
Laminatethemtogether–onesectionof5piecesand
anothersectionwith3pieces.Checktheplansforcorrect
orderofpieces.Usethe2‐56screwstolineupthepieces
properly.Laminatethe1/16”plypiecestothe3‐unit
section,withthe1/8”notchedpiecebetweenthe5‐piece
section.Mountyourmotorinsidethecoreunit.Aholefor
thethreemotorwirestoexitwillneedtobefashioned.
Findthethreedifferentsizedcircularpiecesfortheengine
cylindersaswellasthe3/32”squarebalsacentersticks.
Thisbuildermadeasmallfixturetogluethepiecessquare
andproperdistanceapart.



Assemblethe9cylindercores.Cut9piecesofheavy
paperfromthepatterninthelowerleftcornerofthe
plans.Cutthepapersothegrainallowsthepapertobe
rolled.Thisbuilderpre‐rolledthepaperaroundaSharpie
pen.Gluetherolledpaperaroundthecylindercores.Cut
2piecesofstringabout18”long,glueoneendofthe
stringtothetoporbottomofthepapercylinders.Wind
bothpiecesofstringaroundthecylinder.Gluetheother

FokkerDr.I35”Page3
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13
endofthegluedstringandunwindtheungluedstring.
Youhaveevenlyspacedcylinderfins.Paintwithdopeor
polycrylictofixthestring.Repeatfor8morecylinders.
Gluethecylindersontothemotorcoreusingthe1/8”
notchedpieceforproperspacing.



Paintthemotorunitandaddwhateverdetailyouwish.
Addsomewirepushrodstofinishofftheunit.Add
washerstothetopandleftscrewstogettheproperdown
andrightthrustforthemotor.Thereislotsofroom
behindthecylinderstomounttheESCandnoseweights.

TAILSURFACES
Layoutandgluepartsofthetailsurfacesontheplans.
TailSurfaceswoptionalhorizontalstabcenterbalsaomitted
Don’taddthehornsorhingethesurfacesuntilafter
coveringiscomplete.

LANDINGGEAR
LandingGearTrialFitting
Thelandinggearismadefrom1/16”musicwireandis
attachedtoplywoodcrossmembersinthefuselageusing
Kevlarthreadthreadedthroughholesprovided.Use
EpoxyorCAtostrengthenthejoint.Basswoodfairings
securelyboundtotheuprightscanaddsignificant
strength.Itisalsopossibletofashionashock‐absorbing
axlebyaddingasecondaxleontopoftheonethat
securestheundercarriage.Securethefloatingaxleinthe
centerofitʹsspantothefixedaxlewithKevlarthreadand
epoxy.Rubberbandsareappliedtobothendsofthis
floatingaxlewherethewheelsattachactasshock
absorbers.Thebandsshouldgoaroundboththefixed
andfloatingaxle.Finallyattachthewheelstotheendsof
thefloatingaxle.




FokkerDr.I35”Page4
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13
COVERING
Anylightweightcoveringmaterialcanbeused.Polyspan
withdopeorMinwaxPolycrylicmakesagoodchoice.
Litespanisalsopopular.
Decaloutlinesforthismodelareavailableon
www.aerodromerc.com/decalsinAdobeAcrobatpdf
formatforprintingondecalpaper.Contactpaperused
forkitchenshelfliningmakesexcellentdecals.Printout
thedecalonpaper,gluewithagluesticktothepaper
backingontheshelfpaper,cutthedecaloutwithan
Exactoknifeormicroscissors.Peeloffthepaperand
adheretoyourmodel.Useblackmaterialforthecrosses
andwhiteforthebackgrounds.
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.

Wheels
Paperconesarecutout.Useaballpoint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cutout
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.
INSTALLINGTHERADIOCONTROLGEAR
ServoBay
GettheR/Cgearfittedatthisstage,andalsothemotor.
AileronServos
Aileronservosaremountedinwingandattachedwith
shortthreadedrodstotheailerons.Usea“Y”wiring
harnessconnectortowiretheservostoasingleradio
connection.Ifdifferentialaileronthrowsaredesired,
rotateeachservohornforwardabout20degrees,while
maintainingtheneutralpositionoftheaileron.This
shouldcounteranyadverseaileronyaw.









FokkerDr.I35”Page5
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13
ASSEMBLY
DryFitModel
Wings
Thebottomwingisattachedtothefuselagethroughtwo
sparsconnectingthetwohalvesofthebottomwing.The
bottomwingshouldbeattachedfirst,makingsureitis
alignedproperlywiththefuselage.Thesparsare
designedtoepoxyintotheslotsintheplysides.Then
addtheIPstruttothemiddlewing(Ithasatopindicated
byaTmark)andepoxythemiddlewingtotheplysides
usingthesparsandslotsasaguide.Epoxythebottomof
thestrutintothebottomwing.Atthispoint,thetopwing
canbeadded.TheIPstrutaidsinalignmentofthetop
wing.AgainuseepoxytoattachthetopwingtotheIP
strut.
Themusicwireportionofthecabanestrutsareattached
tothelasercutplywoodparts.Therearcabanewire
halvesareinsertedinto3/32ʺdia.Brasstubingthatis
lashedandepoxiedtoa1/8x1/4ʺbassorsprucecross
memberwhichisepoxiedintoinapre‐cutnotchtheply
risers.ThecabanewiresaretobelashedtotheCA
hardened1/8ʺplycabanestrutsandCAʹedinplace.CAis
usedtofixthewiresinplaceinsidethebrasstubing.
Kevlarthreadorfishinglineispreferredforthisprocess.
Thefrontandrearmusicwiresectionsmeetatthetopof
thecabanestructure.Thisportionofthecabanestrut
attachestothetopwing.Themusicwirescanbeattached
eitherbyoverlappingthemandlashingwiththreador
havethemmeetinsideashortsectionof3/32”brass
tubing.
Thetopofthefuselagebetweenthemiddlewingscanbe
finishedinseveralways:
1)Fashion1/16thsheetingtocovermostofthearea
usingthetopoftheplyrisersasaguide.Fillin
gapswithbalsafiller.
2)Use1/4ʺbalsaandsandtoshape.
3)Coverwithcardstock.
4)Fillwithbluefoam.
Thetopwingisthenepoxiedontothecabaneassembly.
However,thewingadditionprocessshouldbedonelast.
FittingTailSurfaces
Attachtheelevatortothehorizontalstabilizer.
Thehorizontalstabilizerandelevatoraregluedontothe
fuselagefirstandthentherudder.Theruddershouldbe
securelyattachedtothefuselage,astheareaisrelatively
small.
AddingControlHornsOnthePushrodEnds
Slipthecontrolhornsontothewirepushrodendsand,
withboththeservosandthecontrolsurfacescentered,
gluethehornsintotheirslots.Someprefertodelay
addingtherudderuntiltheelevatorcontrolhornis
secure.Thenaddtherudderanditʹscontrolhorn.It
makesthejobabiteasier.
FittingtheRiggingWires
UsestrongthreadorKevlarfishinglineorelasticbeading
cordingtosimulateriggingwires.Usesmallscrews,
fishinghookeyes,straightpinheadsorsmalleyeletsto
attachthelines.These“wires”canaddadegreeof
strengthtoyourmodel.
Batteryhatch
Fashionabatteryhatchfrom1/32”plywood.
BalancingtheModel
Balancethemodelatthepointshown.Itisbestto
positionthebatterytodothisoperation.


FokkerDr.I35”Page6
Copyright©2005‐13M.K.BengtsonAllRightsReservedRev04/13


FLYING
ThemodelshouldROGongrass,pavementorhard
surfaces.Usefullthrottleandfullupelevatorontakeoff.
Oncethemodelisairborne,easeofftheelevatorto
neutral.Letthemodelgainaltitudeslowlyoffthe
runway.Inflight,applyingtoomuchupelevatoratslow
speedsrisks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.Fly
themodeltoalanding,keepingsomepowersothatthe
airflowoverthetailispreserved.Justpriorto
touchdown,givethemodelfullupelevatortoprevent
noseover.Themodelmayrequirecoordinatedturns
usingbothaileronsandruddercontrol.Thisisdueto
adverseyaw.Halvingtheailerondownthrowwill
reducetheeffect.Thiscanbeaccomplishedbyrotating
thecontrolarmoftheaileronservoforwardabout20
degrees.
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.

HerearesomeexcerptsofJohnBoeck’sflightreport.
“TheFokkerDawnPatrolwasinfullforcethismorning.
ROGʹslookscaleandhappeninabout20feet.Themodel
willROGinshortgrasswithoutissue.Fullupelevator,at
fullthrow,isneededattakeofftopreventnoseover.
Climboutslookscalewiththispowersystem.Climbrate
isgoodanditturnsveryquickly.Throwsare1/4ʺaileron,
1/4ʺelevatorw/stoptostopontakeoffandrudderstopto
stop.Theaileronandelevatoraresetupondualrates.
AtthesesettingsIfoundhertobeveryeasyonmeinthe
aironceIfiguredouttheovercorrectionmistakesIwas
making.Itfliesatthepaceofgoodrunat3/4tofull
throttle.“
“Justgotbackfromasecondflightinawindofabout7
mph.Itfliesprettywell,butneedsmuchmoreaileron
throwtogetittoroll.Dualratesorexpoʹsworkwellfor
this.Iʹvefoundshortgrassprovidesmuchmorecontrol
overpavementduringtakeoff.“

Themodelalsoflieswellwiththispowersystem:
GWS400C‐F,12x8GWSHDandusesa3S1500MahLi‐
polybattery.TheJohn’smodelweighsabout30ounces.
Note:John’smodelusedsprucespars.Balsasparsare
nowrecommended.Severalouncesofweightaresaved
andthemodelretainsstructuralintegrity.

CONTACTINFORMATION

Distributedby:
BengtsonCompany
e‐mail:[email protected]
WebSite:www.aerodromerc.com