Thisapproachtodeployinganinflatableboomissimilarinprincipletotheworkingsofacommonparty favor.Inapartyfavor,awiretorsionspringthatrunsalongthesurfaceofthepapertubeintheaxial directionisresponsible forthecontrolleddeployment andbeamstiffnessduringinflation.Thespring providesabalancingtorque,whichresiststhetorqueintroducedbytheinflationpressure.Inorderforthe partyfavortodeploy,thetorquecreatedbytheinflationgasmustbegreaterthantheresistingtorqueof thespring.Bychangingthespringtorque,therateatwhichthepartyfavorunrollsisadjustablefora giveninflationpressure.Furthermore, theinflationpressuregivesthepapertubeenoughstiffnessto supportitselfasastructure. Inthecaseofapartyfavor,oneoftheadvantages ofthespringcontrolleddeployment mechanism isthat thetorsionspringrollsupthepapertubeaftertheinflationpressureisremoved.However,inthecaseof aspacecraftorspacestructure,itisnotusuallydesirabletore-packaninflatableboomafterithasbeen deployedin-orbit.Theproblemwithanembeddedspringisthatitcontinuestoapplytorqueevenafter thetubeisdeployed.Thisresidualspringloadreducesthestiffnessoftheboombecausepartoftheskin tensionthatwouldotherwisebecontributing tothestructuralstiffnessislostinthebalanceofthespring torque.Ultimately,thisindicatedthattherewasaneedforamechanism thatdissipatesenergy,rather thanstoringit,whilemaintaining thesamedeployment characteristics ofthepartyfavorspring. Manyideashavebeeninvestigated todesignamechanism thatenablesthecontrolleddeployment ofan inflatableboom.Oneexampleisamechanism thatusesfrictiontodissipateenergy.Thismechanism operatesbyslidingtwosurfacestogethertogenerateheatasthespoolisrotated.Frictionaldevicesare veryeffectiveinprovidingresistancewithoutstoringenergyandtheyaresmall,lightweight, andsimple. Thedrawbackofthisapproachisthatfrictionaldevicesaregenerallynotrecommended foruseinspace becauseofthepotentialforvariationoffrictionalcharacteristics whenoperatinginthespaceenvironment. Anotherexampleofacontrolled deployment mechanism foraninflatable tubeisVelcro®.WhenVelcro® isapplied tothesurface ofaninflatable tubeinawaythatfacilitates hookandpileinterlocking during rollup,itiseffective inproducing acontrolled deployment withadequate interimbeamstiffness. However, Velcro®isbulkywhenapplied totheentirelengthofatube,Athirdcontrolled deployment mechanism is onethatusesdampers todissipate mechanical energy. Theprimary reasonwhyadamper isnotused, however, isbecause thedamping torqueisafunction oftherateatwhichtheboomisunrolled. When deploying inflatable booms, constant resistance regardless ofdeployment rateallowsforsmoother deployment. Afourthmechanism isbeingdeveloped byILCandAEC-Able, calledaspringbrakedevice. Itusesradialsetsofrollersandsprings todissipate energythrough elasticwork.Themechanism is configured suchthatthestoredspringenergyisreleased asthedevicerotates. Finally, afifthsolution, calledawirebrakedevice, dissipates energybyplastically deforming metal.Itworksbytransferring soft wirefromonedrumtoanother. Intheprocess, thewireisbenttofitaroundthedrum. Explanation oftheWireBrakeDevice Description Thewirebrakeisasimpledevicethatdissipates energybyplastically deforming metal.Thedeviceis housed insidethehubofaspool,whichisusedtorollupaflattened inflatable boom.Thewirebrakeis attached toareaction armthrough acentralshaft,andtheboomendcapinsidethehubofthespool. Thereaction armisconnected toayoke,whichstraddles theinflated portionoftheboom.Theyoke prevents thereaction armfromrotating withthespool(Figure 3).Astheboomunrolls, thespoolrotates relative tothereaction arm.Thewirebrakeresistsmotionofthespool,thuscontrolling theboom's rateof deployment 233