ImmersionRC XuGong User manual

Build GUIDE
Preliminary:v0.321Jan2013

Important Note:
Thisbuildlogiscurrentlyaworkinprogressthatcanreallybenefitfrominputfromanyone
usingit.Pleasesendanysuggestions/updatesto[email protected]andwewillbe
delightedtoincorporatetheminthemanual.
Avideobuildlogisinprogressandwillbereleasedshortly.
Pre-requisites, General
● 2mmHexdriver,forinstallationofthemotormountingscrews,andTNutscrews
● SmallPhillipsscrewdriver(watchmaker’ssize,forHitecselftappingservoscrews)
● Battery,HobbyKingZippyCompact4s4000recommendedformostbuilds.Seethe
section‘BatteryChoices’formoredetails.
● 3MVHB(orsimilar)doublesidedtapeforESCmounting
● M3x8mmscrewsformotormounting(lowprofilehead,2mmorless)
● FlightController,OpenPilot,orDJINazarecommended(seebelowforaDJIspecific
build)
● Twolengthsof~AWG14wire,redandblack,approx.10cmlong(Batteryhookup)
● Twolengthsof~AWG20wire,redandblack,approx.20cmlong(Nazahookup)
● ExtendercablestoconnectthemotorstotheESCs,lengthdependsuponmotorsand
ESCsused.
● XT60,orDeansconnectoraccordingtothebatteryused
● 4mmsinglesidedselfadhesivefoamforcameramounting
● Tiltservo,HS65MGhighlyrecommended
● FPVCamera,FatSharkCMOShighlyrecommended
Pre-requisites, Build using DJI Components
● DJINazaLite,orNazaMV2(smallerBECfromtheLiteispreferredformostbuilds)
● 4xDJI2212/920kVmotors,orsimilar
● 8”DJIPhantomprops(smallarmversion),orDJI1038props(newstyle)forthelongarm
version

The Anatomy of a XuGong
The Foldable Arms, Motor Mounts, and Motors
Thefoldablearms,milledoutofasolidplateof5mmAluminium,allowtheXuGongtocollapseto
asizewhichfitseasilyintotheaverageShoeBox/HandBag/BackPack,etc.
Whetherthelong,orshortarmversionisbuilt,thepivotpointsallowthefourmotorstopivotinto
thecenteroftheframeforstorageandtransport.Whileinthisposition,thepropbladesare
mucheasiertoprotectfromdamagethantheyareonamoretraditionalquadcopter.

The Anti-Jello Plate
TheAntiJelloplateconsistsofanFR4plate,laidoutwithPCBtraces,whichroutethepower
betweenthebattery,andthefourESCs.
Itincludesaselectionofholesforsiliconedampers,thenumberofwhich,andthedurometer
(hardness)ofwhich,determinethetradeoffbetweenvideoquality,andaerobaticflight
characteristics.
Twokindsofdampersareavailable,theblackonesincludedwiththeproduct,whicharegoodfor
slowflyingphoto/videowork,andsomeharderreddampers,formoreaggressiveflying.
Thereddampershaveaslightlydifferenttooling,toleavemorematerialinthecenter.
The Frame Assembly
TheFrame,constructedmainlyofaverysturdyblackFR4material,holds(andprotects)the
battery,andalloftheelectronics.Theflightcontrollersitsinaprotectedboxinthecenterofthe
frame.TheA/VTx,andUHFRxcanoptionallybeplacedintherecesseseachsideoftheframe,
keepingthemprotectedagainstcrashdamage.
AnalternativeframeassemblywillbemadeavailableinearlyJanuary2014,whichwillbemade
ofcarbonfibre,withlightweightanodizedaluminiumnutsandscrews.
ThisversionworkswellfortwotypesofQuadflyers,thelongrangefanatic,whowantstoshed
everygramfromtheweightofthequad,andtheposer:),whojustwantsaquadtolook
fantastic.

The GoPro Camera Assembly
TheGoProcameraassemblyincludesapaddedsupportforaGoPro3(anyedition),anoptional
supportforanSDcamera(FatSharkCMOS,with‘GoProequivalent’Lens,highlyreommended).
ForthestandardversionoftheXuGong,asimpletiltonlygimbalusingaHitecHS65MGservo
(orsimilar)issupported.Thisisafairlyrobustmechanism,whichworkswellforaquadwhich
willbecrammedintoabackpackduringtravel.
The‘HB’versionofthisservoworksalso,butthegearsareabitfragileforthisapplication.
AbrushlessgimbalisunderdevelopmentfortheXuGong,andwillbeavailableinearly2014.
Several3rdpartybrushlessgimbalshavebeensuccessfullyusedontheXuGong,includingthe
Tarot,whichwithafewsimplemodificationscanbemountedontheXuGong’sfrontbulkhead.
Building the XuGong... Component Selection:
Thereareahugenumberofdifferentcomponentsavailabletobuildmulticoptersthesedays.The

costofthesecomponents,alongwiththeirquality,andcompatibility,varieswidely.
Thecomponentselectionsbelowarebaseduponourexperiencetodate,andwillresultina
successfulfoldablequadcopterbuild.
Flight Controller
MostoftheXuGongprototypesbuiltbytheImmersionRCteamhaveusedvariousversionsof
theDJINazaFlightcontroller.
Thisexperiencewillbereflectedinthisbuildlog,itwillbetheflightcontrollerusedduringthe
build.
TheNazaMLiteis,insomeways,moresuitablethanthenewerV2,duetoitsmuchsmaller
(andthuseasiertomount)LED/Powerunit.
Ofcourse,anyflightcontrollerdesignedtoflyquads,assumingreasonablephysicalsize,willdo
justfineasareplacementfortheNaza.
ForusewiththeOpenPilot,andsimilarFCs,astandardpatternof4holesisprovidedonthe
bottomplateoftheframe.
Motors
Asfortheflightcontroller,mostoftheXuGongprototypeshaveusedthestockDJImotors(DJI
2212/920kV).Thesearegenerallypricedfairlyreasonably,andfittheframearmsnicely.
Theyarealsocompatiblewitheitherthe8”DJIpropsusedonthesmallerversionoftheXuGong,
theXuGong8,andthe10”(1038)propsusedontheXuGong10.
Props
OneofthemostcommoncausesforcrashingduringtheXuGongdevelopmentwasdueto
propsbreakinginflight.Theearlier8”DJIpropsweregenerallytheculprit.
Graupner8”carbonfibrepropsdoworkasreasonablereplacements,butrequireasmall
amountofdrilling/filingtoallowthemtofitontheshaftsofthestockDJImotors.
Forthe10”versionoftheXuGong,thenewer1038propsfromDJIworkverynicely,andareyet
tofailforusinflight.
Tip:EventhoughtheXuGongisdesignedtoreducethetransmissionofvibrationtothe
camera,wellbalancedpropsarestillagoodidea.
Battery
SeveralbatteriesarecompatiblewiththeXuGong,andshouldbeselectedbaseduponthekind
offlightcharacteristicsrequired.Abatterybox30mmheight,with2.4mmrequiredforthe
retainingringoftherubberfeetmeansthata28mmtallbatteryfitscomfortably,butnothingtaller.
Battery
mAh
Height
Width
Length
Weight
Status/Time

NanoTech3.3
2550C
3300
28mm
44mm
135mm
327g
recommended
Lunenier3.3,
4s,35C
3300
27mm
44mm
135mm
330g
Goodcandiate,
tobetested
ZippyCompact
25C,2700
2700
21mm
44mm
138mm
278g
12minuteflight
time
ZippyCompact
4000,25C
PREFERRED
4000
28mm
43mm
145mm
385g
210mAh/minut
eofflight
w/1038props
NanoTech2.2
35870C
2200
33mm
35mm
105mm
246g
tootallfor
betas
Thebatteryboxdimensionsare:30mmHx48mmWx125mmdeep
RememberthatthebatteryplaysabigpartinthedeterminationoftheCenterofGravityofthe
XuGong.Aheaviercamera,orabrushlesscameragimbal,canbecompensatedforbyaheavier
battery.Inaddition,anoseheavyXuGongcanbebalancedbyslidingthebatteryrearwardsin
thebatterybay,andpaddingthefrontofitwithasmallblockoffoam.
Forpureflighttime,theZippyCompact4000,4s,25C,isagoodchoice(HobbyKingPart
NumberZC.4000.4S.25).ThispackisusedonmostoftheImmersionRCprototypeXuGongs.
A/V Transmitter
Thiswillbealittlepredictable,butwedohighlyrecommendanImmersionRCproductfortheA/V
transmitter.Forlicensefreeuse,on5.8GHz,the25mW5.8GHzTxisagoodchoice,andwill
complywithCEstandardsforuseinEurope.
Forlongerranageuse,orwherearadiolicenseisavailable,thepopular600mW5.8GHz
transmitterisalsoaverygoodchoice.
ThetopandbottomframeplatesforthestockXuGongaredesignedtofitthetransmitter
betweenthem,protectingitfromdamagecausedbymost‘hardlangings’.
Asmallpieceof3MVHBtapekeepsthetransmitterfirmlyattachedtothesideofthequad.
A/V Transmitter Antenna
ThebottomplateoftheXuGonghasa‘hook’designedtomountoneofour5.8GHzSpiroNET
omnidirectionalantennas.Thisispositionedsoastokeeptheantennabelowthecraft,inclear
viewofthegroundbasedreceiver,andthecorrectdistancefromtheA/VTxforthestandard
cablelength.
FPV Camera
EventhoughthevideooutputofthegimbalmountedGoPromaybeusedasanFPVcamera,it

isnotreallyrecommended.GoProcamerashavebeenknowntoshutdown,losingtheirvideo
feed,forseveralreasons(toohot,toocold,deadbattery,..justbecauseitisthethirdSundayof
themonth…).
ToavoidthestressofhavingtousetheFlightController’s‘ReturnHome’functiontorecovera
‘blind’quadcoper,asecondaryFPVcameraishighlyrecommended.
ThegimbalwasdesignedforusewiththeFatSharkCMOScamera.Lightweight,andwithvery
goodperformanceindifficultlightingsituations.
AwideanglelenseisrecommendedinordertolettheCMOScameraseethesame(orsimilar)
FPVastheGoPro.ThismakesframingshotswhilefilmingwiththeGoPromucheasier.
Radio Control system
Continuingonthepredictabletheme,wehighlyrecommendtheImmersionRCEzUHFreceivers
foruseinthecontroloftheXuGong.ThesecanbeeasilyprogrammedtoemitaPPMstream
fromoneoftheservooutputs,whichiscompatiblewiththePPMmodeoftheNazacontroller.
Thisgreatlysimplifieswiring,andenableseventhe4channelEzUHFreceivertosupplythe5
channelsrequiredtoflythequad,plusadditionalchannelsforgimbal(andother)control.
AnyoftheEzUHFreceivers,canbeusedwiththeXuGong,thislistcurrentlyincludesthe4
channel,8channel‘lite’,and8channeldiversity.
Attheotherendoftheradiolink,thereareseveralradioscompatiblewiththeEzUHF.Our
currentfavouriteistheFrSKYTaranis,withournewJREzUHFModulepluggedintheback.
WiththeEzUHF,evenwiththe4channelunit,radiocontrolrangewillexceedtherange
achievablebythequaditself.
FortheEzUHFRxAntenna,afull½wavedipoleishighlyrecommendedifrangeofmorethana
fewkilometersisrequired.
Thisantennacanbeconstructedusingthemonopoleantennaswhichareshippedstockwiththe
EzUHFReceivers.Takealengthofthecablecommonlyusedforbicyclebrakecables,the
samelengthasthemonopole,andsolderittothesideofthemonopoleSMAconnector.The
flexiblenatureofthiscablewillallowtheantennatodeformduringtakeoffandlanding,andfold
outtocreateasoliddipoleduringflight.
Mountthereceiveronthebackofthequadcopter,nearthe‘tail’,withthedipolemounted
verticallybehindit.
Building the XuGong... Basic Concepts:
Concept #1: Introducing the IRC T-Nut
TheIRCTNutisauniquedesignwhichallowsverystrongjointsbetweenFR4plates,while
captivatingthenylocnutduringassembly.

Usingtheseiseasy,justinsertthenylocnutintotheplasticpart,andpushthetwointothe
TSlot.ThepartswillberetainedtoallowthesecondFR4platetobemated,andthescrew
inserted.
Tip:ifyouhavedifficultiestoinsertthenylocnutandtheplasticpartintheTSlot,firstsqueeze
thelowerpartinandtwistthetopintheholeinsteadofinsertingitfromtheside

Concept #2: Anti-Jello Dampers

Jello(orratherJellyasitiscalledintheUK),mightbegoodtoeat,butitisnotappreciatedin
aerialvideoproductions.TheXuGongarmassemblyismountedtotheframeusingantivibration
dampers,similartothoseusedontheDJIZenMuse.
Toinstallthem,firstpushonesideofeachofthemintotheholesinthetopoftheframeplate.If
theyresist,agentlerotationgenerallyconvincedthemtodropintoplace.
OncethePCBcontainingtheupperarmassemblyisreadytomount(checkanddoublecheck
thatallsolderinghasbeencompletedbeforemountingit),pressitlightlyagainstthedampers,
andonebyone,teasetheupperpartofthedampersthroughtheholeinthePCB.
Apairoftweezers,liketheonesbelow,workatreatforteasingthesein.Justclosethe
tweezers,sneakthemaroundthebackofthedamper,andusethemtopoketheupperriminto
thehole.
Building the XuGong... Step-by-Step:
Step 1: GoPro mount

a) Servo mount: HS65MG
UsingtwooftheselftappingscrewssuppliedwiththeHS65MGservo,mounttheservointoone
oftheGoPromountingarms,asshownbelow:
b) Servo Horn
UsingthesecondpairofselftappingscrewssuppliedwiththeHS65HBservo,screwtheservo
hornontotheleftsideGoPromountingplate,asshownbelow:
c) Right-side GoPro bearing
TakeaM3x10mmscrew,andpassitthroughtherightsideGoPromountingplate,sothatthe
headofthescrewsitsinthemilledrecessintheplate.Mounttherightsidemountingbracket,

andsecurewithanM3nylocnut.

d) T-Nut installation, Finalize GoPro Assembly
InstalltheplasticnutholdersintothetwoGoProsideplates.
MountthetwoplatestotheGoProfrontplate:

Mountthelowerandbackplates.Notethepositionoftheslotinthebackplate,andthe
correspondingslotinthelowerplate.
Finally,screwtheservohorntotheservo.
Tip:Toavoidbrokenservopinionslaterinthebuild,rotatetheservohornontheservosothat
whenthemountislevel,theservoisatit’smidpoint.

Step 2: The Frame
a) Silicone Feet installation
Firststepinbuildingtheframeistoinstalltherubberfeet.Don’tleavethisuntiltheend,since
theyaredifficulttoinstalloncetheframeisassembled.
Layoutthebottomframeplateasshownbelow,andteasethefeetintoplace.
NOTE:The‘Hook’asithasbeendescribed,inthetopleftofthephotohereisformountingthe
5.8GHzSpiroNetAntenna.Asmallpieceof3MVHBtapeholdstheantennasecurelyonthe
bottomoftheQuad.
b) Anti-Jello Damper installation
Theantijellodampersshouldbeinstallednext,asshownbelow.Again,don’tleavetheseuntil
laterintheinstallationprocedure,sincetheyaredifficulttoinstalllater.

c) Frame Side-plate Install
Nextstepistoinstallthesideplates.Usethepicturesbelowasaguide,toinstalltheTNut
assemblies,andscrewtheframetogether.
Don’tforgettheinner‘firewall’,whichprotectstheflightcontrollerfromarunawaybattery,inthe
eventofaseriouscrash,andthefrontfirewall.
Finallyyoushouldhavesomethingthatlookslikethis,frombelow:

Don’tcloseitjustnow,asyou’llstillneedaccesstotheinsidetofixthecontrollerandtheGPS
mount.
Step 3: The Foldable arms
Power Distribution Plate
FirststeponthefoldablearmsistoattachthemtotheroundpowerdistributionPCB.
DothiswiththesuppliedM4bolts,andnylocscrews.
NotethatthePCBismountedunderthearms,asshownbelow:

ESC Mounting
TheESCssitbelowthecenterspiderasshownbelow.Onbetaunitsthebestwaytomount
themiswithapieceof3MVHBdoublesidedtape.Avoidmountingthemwithtiewraps,or
anythingelsethatwrapsaroundthecenterspider,sincethatwillimpedetheabilitytofoldthe
copter.
Tip:Ifpossible,trytoavoid‘peel&stick’typethickerfoamtapes,theadhesiveonthesewill
lastforashortwhile,buteventuallywillgiveway(thiswasrecommendedinpreviousversions
ofthebuildlog)
Tip:NotethattheESCsshouldnotbemountedtooclosetothecenterplate,orthecapacitor
thatisusuallystickingoutoftheendoftheESCwillbecomeagreatwaytotransmitvibration
betweenthearm,andtheframe.
Soldering Cables to the Power Distribution Plate
NowthattheESCsareinstalled,youcancompleteallofthesolderingtothepowerdistribution
plate.
StartingwiththeESCs,cuttheESCpowerwirestothecorrectlengthtoallowthemtobe
soldereddirectlyontothepadsontheboard.NotethatforDJIESCs,thepositiveandnegative
terminalsarepositionedcorrectlytolineupdirectlywiththepowercables,withoutcrossing
wires.EnsurethatwiththeESCsused,theredESCpowerwireissolderedtothe+terminal,
andtheblackESCpowerwireissolderedtotheterminal.
Warning:Donotgetthesewiresbackwards…ESCsarenotveryforgivingifwiredtoaLiPo
backwards!.Check,anddoublecheck!
Next,soldertwolengthsof14AWG(orsimilar)siliconecoatedwiretothepadsmarketBATT.
Tostartwith,usealengthofapprox10cm,thesecanbecutdowntothecorrectlengthlater
whenthebatteryisselectedandinstalled.
NextstepistosoldertwolengthsofthinnersiliconecoatedwiretothepadsmarkedNAZA.Start
withalengthofabout10cm,andasforthepowercablesabove,thesewillbecutdowntolength
laterinthebuild.Forboththepower,andthesecables,trytousecolorcodedwire,redand
black,toavoidanymagicsmokelaterwhentheyarehookedupbackwards.
FinalsolderingstepistheA/VTxpowercable.Thisshouldbeapprox10cmlong,andbe
solderedontothepadsmarkedNAZA,sincetheyneedtoexitontherightsideofthequad,
nearesttheantennamountonthelowerframeplate.TheframeisdesignedforanImmersionRC
600mWTx,mountedintherecessintherightsideoftheframe,whichprotectsitfromimpact
fromallsides.

Onceallofthecablesaresoldered,toreducespaghettilater,takeacoupleofnylontiewraps
andbundlethe4ESCcablestogetherclosetothepowerplate.
Thisassemblyshouldlookjustlikethephotobelow.Pleasedouble,andtriplecheckthepolarity
ofallofthewiringatthispoint.Theplateisnoteasytoremoveandreinstalllater.