Bengtson Company Pfalz DIIIa User manual

PfalzDIIIa41”
Copyright©2005‐11M.K.BengtsonAllRightsReservedRev07/11
PfalzDIIIa41”
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R/CScaleModelInstructions
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CONTACTINFORMATION
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ThePfalzDIIIawasdesignedbyM.K.Bengtson
PrototypebyBrianAllen
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ManufacturedandDistributedby:
BengtsonCompany
e‐mail:[email protected]
WebSite:www.aerodromerc.com

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Copyright©2005‐11M.K.BengtsonAllRightsReservedRev07/11
PFALZDIIIa
ThankyouforpurchasingthePfalzDIIIamodelfor
electricflight.
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FinishedModel
THEMODEL
AsemiscaleadaptationofthePfalzDIIIa,thismodel
isdesignedtoberelativelyeasytobuildandexciting
tofly.
SPECIFICATIONS
Morethan260lasercutparts
Scale:  1/9
Channels: R/E/A
Wingspan: 41ʺ
WingArea: 431sqin
Weight: 28ozreadytofly
PowerSystem:AXI2808brushless
Prop:  11x7
Wheels:Balsa&plywoodNeoprenefoamtires
AirfoilType:Flatbottomed
Spinner: Builtupfoamandfiberglass
Covering: Litespan,Polyspanoriron‐onplastic
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.
WINGS
WingConstruction
Pindown,overtheplan,theleadingedgestock,
trailingedgestock,sparsandwingtips,gluingas
required.Sandtheleadingedgestocktoberounded
andmeettheribs.
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UpperWing
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LowerWing
Sheetedcentersectionsarefeaturedinbothwings.
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TopWingCentersection
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.Thereisnodihedralineitherwing.
IPstrutattachmentpointsaremadefromshort
sectionsof3/32”brasstubingepoxiedinplacedinside
thewings.

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AileronServo
FUSELAGECONSTRUCTION
Thefuselageisbuildusing1/16”balsasheetedformer
andkeelconstruction.Thelowerwingisbuiltinone
pieceandgluedtothefuselage.Thefuselageand
lowerwinghaveundercarriageattachmentpoints.
Beginbyassemblingthetopandbottomkeelsonthe
plan.Assembletherightandleftsidekeels.Theright
sidekeelisshorterthantheleftsidekeel.Theshorter
keelprovidesforrightthrust.Thedownthrustisalso
builtinduetothelengthdifferenceinthetopand
bottomkeels.
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FuselageConstructionDetail
Buildtheleftfuselagesideframeovertheplan
includingthesidekeel.AddthefrontformerF1and
thelastformerF11thenthelongersidekeel.Usingthe
sidekeelasastabilizer,theotherformersareadded.
Note:themainfuselagesideformersarelabeledon
thebottom.Theyshouldbeplacedsothatthelabelis
readablei.e.notupsidedown.
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FuselageConstructionDetail
Theframeisremovedfromthebuildingboard.Glue
theF1andF11formercarefullyandaddtheshorter
sidekeel.Theremainingformersaregluedtothe
frameusingtheleftsideasaguide.
FormersF12areplacedonbothsidesofthekeelto
formaslotforthehorizontalstabilizersotakecarein
gluingtheseinplaceorthehorizontalstabilizerwillbe
misaligned.
AttachF0toserveasabaseforthe1/16”plymotor
mount.Becarefultoensurethatrightanddown
thrustispresentatthistime.Itmayberequiredto
reamoutF0abittoallowclearanceforthemotor
housingsodryfitthemotoratthispoint.
Therearemarkingsoftheformersthatshowthe
locationsofthecabaneandlandinggearattachment
crossmembers.Madefrom1/4”squarebassorspruce,
theseshouldbeattachedatthistime.Itmaybe
preferabletopredrill1/16”holesintheendsbefore
attachingthecrosspiecestotheframe.Alternate
structuresmaybefabricatedfrom3/32”x1/16”and
3/32”x1/4”basswoodstripstock.Usingthismethod,a
channelisformedthatpassesthroughthecenterofthe
¼”squarecrosspiece.Nodrillingisrequired.
AlsoaddtheotherformersF1aandF4athatserveas
attachmentpointsfortheremovabledummymotor.It
iseasiesttoattachthe4‐40blindnutintheholeinF1a
beforegluingitinplace.
Fashionabatterytrayoutof1/8”balsaandscrapcross
piecesatthistime.Note:theAXImotorisattachedto
thefrontmotormountthroughthedummymotor
accessarea.Besurethatthereisroomtoattachit
beforeaddingthetray.
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PrefittheR/Eservosonbasscrosspiecesinthecockpit

PfalzDIIIa41”Page4
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area.Itisusefulatthispointtodeterminewherethe
pushrodsorpull‐pullcablesexitthefuselageatthis
pointinconstruction.Itwillnotbeaseasyafterthe
sheetingisapplied.
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1/16thbalsasheetingisemployed.Plankingmaybe
preferabletosheeting.Anexcellentarticleshowing
howtoplankisfoundhere:
http://www.modelairplanenews.com/how_to/strip_pla
nk1.asp.Thereferenceisalsofoundontheplan.If
plankingisused,use3/32”balsaandsandthebalsa,
mercilessly,to1/16”thickness.
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SheetingDetail
Ifsheetingistobeused,choosethelightest,softest
1/16”balsa.Cuttoaroughshapeandsoakinhot
waterthenbindtothefuselagewithpapertoweland
rubberbandsandletdry.Thisprocesswillsetthe
curveinthebalsa.Usebalancedsectionssothatno
distortionsoccurinthefuselage.
Useblue/pinkStyrofoamforthetailendofthe
fuselageandsandtoshape.Theareacanalsobe
coveredinbalsa.
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Afterthefuselageissheeted,thecockpitandkeel
sectionforthecockpitopeningiscutout.Cutaway
thetopofthekeelandformersinthearea.This
openingisusedforaccesstotherudderandelevator
servos.
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DummySpandaumachinegunpartsareincludedin
thekit.Theyareassembledasshownontheplanand
aprintedcardstock“barrel”iswrappedaroundthe
roundbalsadisksformingthecoolingjacket.Theguns
shouldbefashionedwiththespentammoshootson
oppositesides.Thensetthegunsintocutoutsinthe
topofthefuselageBEFOREthetopwingisattached.
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TAILSURFACES
Layoutandgluepartsofthetailsurfacesontheplans.
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RudderandVerticalStabilizer
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ElevatorandHorizontalStabilizer
Sandthetailparts,roundingoffalledges.Don’tadd
thehornsorhingethesurfacesuntilaftercoveringis
complete.

SPINNER
Thespinneriscomposedoffiberglassedbluefoam.
Thespinnerismadefrombluefoamwhichistack
gluedtoapieceof1/32”ply.Epoxyashort1/4”
diameterdoweltothebackinthecenterofthedisk.
Placetheassemblyinadrillchuckandsandthefoam
toshapewhileitspins.Glassthefoamusingstandard
glassingtechniques.(Note,MinwaxPolycrylicisan
excellentsubstituteforepoxy).Whentheepoxyis
ready,cuttheexcessfiberglassaway.Thenremovethe
plywoodandcarveoutthenecessaryrecessforthe
propeller.Drilloutthedowelontheplywooddisk.
Gluethespinnertotheplywooddiskafterthepropis
mountedtothemodel.Itshouldbeperfectlyaligned
withthefuselage.Itlookscomplicatedbutinpractice
theprocessgoeseasilyandworksverywell.


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Spinner
COVERING
Any lightweight covering material can be used.
Polyspan with dope or Minwax Polycrylic makes
a good choice Litespan is also popular. Brian used
an iron on plastic covering similar to Solite.
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.
Ifalozengepatternisdesired,decalsoutlinesforthese
arealsoavailable.RefertoourJuneissueofour
Webzineforanexcellentarticleonhowtomake
lozengepatters.
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.

INSTALLINGTHERADIOCONTROLGEAR
ServoBay
Getthebulkofyour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.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.

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ASSEMBLY
Wings
Gluethebottomwingontothefuselagefirstmaking
surethefuselageisalignedstraightandnotleaningto
oneside.
Fashionalowerwingfairingfromsoftbalsaor
blue/pinkfoam.Apapertemplateisshownonthe
planforacardstockversion.
IPandcabanestrutsaremadefromalaminationof
two1/16”balsapiecesandaninner1/32ʺplywood
core.Twoouter1/16ʺbalsasidesareattachedtoa
1/32”plycorethatstraddlesa1/32”musicwire.The
wiresarecuttothelengthsshownandembeddedinto
thewoodpartsandsandedtoaroundedshape.The
endsofthewirearecladwithshortʺbootsʺof1/16ʺ
brasstubing.Thecompletedstrutsareattachedby
insertingtheʺbootsʺintothe3/32ʺbrasstubingbuilt
intothetopandbottomwingsandfuselage.Whenall
incidenceandalignmentchecksarecompleteusea
dropofthinCAtolockthewingstogetheratthe
CabaneandIPjoints.Alternately,5‐minuteepoxycan
beused.
LandingGear
Thelandinggearisattachedafterthelowerwingis
attached.Thegearismadefrom1/16”musicwire.
Thefrontmountsareinsertedintotheholesinthe
crosspiecesinsidethefuselage.Therearmounts
attachtoaplywoodplateonthebottomofthelower
wing.Usesmallstripsoftinplatebendintosaddle
clampsandsmallscrewstoattachthegear.TheLG
arefashionedaroundtheprecut1/8”plystructures.
Theseplytemplatesserveasafairingandareusedas
atemplateforbendingthemusicwire.

Theplyandwirearetobeattachedtoeachotherusing
KevlarorNylonthreadwithCAglue.Foradditional
strength,attachareinforcingsectionofmusicwireon
theleadingandtrailingedgeoftheslottedply
undercarriage.Bendtheendsofthewireandlashto
themusicwireLG.Ashock‐absorbingaxleis
constructedbyattachingtheaxletotheply
undercarriageatthepointsshownontheplan.3/32”
brasstubingservesaswheelhubandaxlespacers.Use
rubberbandsattheendswherethewheelsattachto
providetheshockresistanceforthefreelymovingaxle
andwheel.Sandtheplywoodtoaroundedshape.
Note:soakingwiththinCAhardenstheliteplyand
thisaddsconsiderablestrengthtothegear.Epoxythe
plywoodpartstogetherforadditionalstrength.When
complete,thelandinggearisverystrong,aligned
properlyandveryclosetoscale.

Tailskid
Thetailskidisformedfromalasercutplypieceand
shouldbereinforcedwith1/32”musicwire,lashedin
placewiththread.Thetailskidtakesalotofabuseso
CAhardenitandwrapittightlywiththread.

DUMMYMOTOR
Assemblethedummymotorfromthebalsaparts
suppliedandsandtoshape.Notallthepartsofthe
enginearesuppliedassomearebestfabricatedfrom
othermaterials.Solid16gaugecopperelectricalwire
(blackinsulation)makesanexcellent“radiatorhose”.
Thedummymotorisalsothebatteryhatch.Itfeatures
a1/4”dowelthatslidesintoaholeinaformerF4a
insidethefuselage.Thefrontcylinderhasavertical
holethatpermitsa4‐40nylonbolttoholdthemotorin
place.
FittingTailSurfaces
Thehorizontalstabilizerfitsintoaslotinthesideof
thefuselage.InsertanddryfittheelevatorusingCA
hinges.Theverticalstabilizeralsofitsintoaslotinthe
topofthefuselagekeel.
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.
FittingRiggingWire
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”addadegree
ofstrengthtoyourmodel.WindsockDatafiles“Pfalz
DIIIa“publicationhasdetailsonriggingplacement,
colorschemesandmarkings.Availableat
http://www.byrdaviationbooks.com/
BalancingtheModel
Balancethemodelatthepointshownontheplan.It
mayberequiredtouseabitofleadtobalancethe
model.

PfalzDIIIa41”Page7
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
FinishedModelReadytoFly
FLYING
Letthemodelgainaltitudeslowlyofftherunway.
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.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Brian’smaidenflight
report.
“WegottothefieldandwhilethePfalzwascharging
weflewotherplanesandhadagreattime.Isetheron
therunwayandpoweredherup.Shewasoffthe
groundislessthan25ftwithminimalrudderand
climbedoutnicely.
Iflewherforabout7minuteswithseverallandings
andtakeoffsfortrimadjustmentsetc.hadthree
takeoffsandlandings.Shelooksabsolutelystunning
intheair.IhadtoturntheelevatorratesupasIran
outofelevatoronacoupleofthelandings,when
turnedupthelandingswerefine.“
CONTACTINFORMATION
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