MarkusEckstein,HendrikLbberdingandMarcLocke(left-right)withthesuncar.
A3,022-kilometerraceacrossAustraliapoweredsolelybythesun.AteamofstudentsfromRWTHAachenUniversityareenteringtheWorldSolarChallenge—withthehelpofspecialistsfromPorscheMotorsports.
Asmoothandnearlysoundlessstart.WithaPlexiglasdomeonitsflatbodyandthedoublekeelofacatamaran,itlookslikeanapparitionfromthefuture.Yetitalsolookssomehowfamiliar,likeafantasyvehiclefrom1960s-eracomicbookswhosecoloredlineshadusdreamingofthegroundbreakingtechnologiestocome.Andnowoneofthosedreamsishummingrightpastus,withzeroemissionsbecauseit’sfueledbythesun.
TheSonnenwagen,or“suncar”asthesolar-poweredvehicleiscalled,rollssoftlytoastop.ChristianeRupp,HendrikLbberding,andMarkusEcksteinimmediatelystarttheirinspections.MarcLocke,thedriver,climbsoutoftheausterecockpitandremoveshishelmet.TheyallstudyateitherRWTHAachenUniversityortheAachenUniversityofAppliedSciences.They,andaroundfortyoftheirfellowstudentsonthe“SonnenwagenAachen”team,haveanambitiousaim:tocompletetheWorldSolarChallengeinAustralia,theworld’smostfamousraceforsolar-poweredcars.It’s3,022kilometerslongandnocakewalk.
Essentialdataanalysis:ProjectdirectorHendrikLbberding(center)discussestheresultswithMarkusEckstein(left)andMarcLocke.
Thestudentsdesignedthecarthemselves.Theyworkedonitfortwoyears,applyingtheirskillsfromawidearrayofdisciplines.InspiredbyareportontheWorldSolarChallengein2015,theystartedwithablankpieceofpaper.Sincethenthelightsintheirsmalllabhaveburnednearlyaroundtheclockandtheideaofefficiencyhasneverlefttheirminds.Whetherappliedtotherollingresistanceforthetires,thecapacityofthebatteriesandthesolarcells,ortheuseofthebudgetattheirdisposal,efficiencyisthekeytosuccess.It’sachallengenotonlyfortheSonnenwagenbutalsoforthe919Hybrid—theLMP1prototypethatgavePorscheitsthirdsuccessivevictoryatthe24HoursofLeMansthisyear.Fortheup-and-comingengineersinAachen,itmadeperfectsensetoworktogetherwithspecialistsfromthesports-carmakerinStuttgart.ThePorschemotorsportexpertsaretherefortheteamwiththeirexpertiseandfinancialsupport.
Thestudentshadalreadyputexcellenttechnicalsystemsintoplace.Theygavetheirsolarvehicleastabletubularsteelframethatcarriesallthecomponentsandensurestherequisitecrashresistance.Itsaerodynamicallyoptimizedchassisconsistsoflightweightfibercomposites.Some260siliconsolarcells,whichchargeacustom-madelithium-ionbatterypackoftheirowndesign,coverasurfaceofjustoverfoursquaremeters.Thestudentsalsodevelopeda135-voltwheelhubmotorwithanoutputof1.4kW—hardlymorethanahairdryer,yetenoughtopowerthetwo-hundred-kilocartoapproximately135kmh;however,thisisnottheiraim.Atanaveragespeedof70to80kmh,thebatterywillrunforfourhours,givingthesolarcararangeofagoodthreehundredkilometers.
TheSonnenwagen’sdriver:MarcLockehastobefitbecausetemperaturesinAustraliacanreach45degreesCelsius.StudentChristianeRuppmakessomefinaladjustmentsbeforethetest-drivebegins.
“Ourmainaimistofinishtherace,”saysprojectdirectorHendrikLbberding.“Manyofthecarsthatenteredthe2015WorldSolarChallengefailedtomeettherequirements.”Toheadoffthisfaterightfromthestart,nothingcouldbemorevaluablethantheexperiencegainedbythePorscheLMPteamintheFIAWorldEnduranceChampionship.Itsbroadrangeofexpertisecoverstrickytransportlogisticsfortheflammablebatterypacks,precisionweathermonitoringtechniques,andbrakeenergyrecoverysystems.Likethe919Hybrid,theSonnenwagenrecoupssomeofitsdriveenergywhilebraking.PreparationshaveevenincludedtestingthesolarcarinthewindtunnelatthePorscheDevelopmentCenterinWeissach.
“ThestudentsfromAachengototheabsolutelimitindevelopingtheirracecar,justlikewedo,”saysPorscheLMPteamdirectorAndreasSeidl.Helistsafewmoresimilarities:“Suchmajortopicsaslightweightconstruction,cooling,efficiency,high-performanceelectricdrives,andaerodynamicsoverlapwiththerequirementsforour919Hybrid.”Asfarasthestudentsareconcerned,the919Hybrid—withitsthreevictoriesatLeMans—isnotabadrolemodel.
ByKlaus-AchimPeitzmeierPhotosbyThorstenDoerk
TheWorldSolarChallengeinAustraliaisconsideredthetoughesteventforsolarcarsworldwide.ItwillbeheldforthefourteenthtimefromOctober8toOctober15ofthisyear.ItrunsstraightthroughtheOutbackfor3,022kilometers,alongStuartHighwayfromDarwininthenorthtoAdelaideinthesouth.Contestantshaveonlysixdaysandcandriveonlyfromeightinthemorningtofiveintheafternoon,includingbreaks.Theymaynotgobelowanaveragespeedof65kmh.Driversarerequiredtodrinktwolitersoffluids—anabsolutenecessityattemperaturesofover40degreesCelsius.
*ThedatapresentedherewasrecordedusingtheEuro5testprocedure(715/2007/EC,692/2008/EC,566/2011/ECandECE-R101/01)andtheNEDC(NewEuropeanDrivingCycle).Therespectivefigureswerenotrecordedonindividualvehiclesanddonotconstitutepartoftheoffer.Thisdataisprovidedsolelyforthepurposeofcomparisonbetweentherespectivemodels.Fuelconsumptionwasrecordedonvehicleswithstandardspecification.Optionalequipmentmayaffectfuelconsumptionandvehicleperformance.FuelconsumptionandCO2emissionsarenotonlydeterminedbyavehicle’sfuelefficiency,butalsobythedrivingstyleandotherfactorsirrespectiveofvehiclespecification.