Clean FormulaforSuccessFormulaEismakingastandatthehighestlevelofmotorsport–butwhatishappeninginthelowerformulae?
WiththeriseinpopularityofFormulaE,electricvehicleracingis beginning to conquer theworld of motorsport - bringingthe support of not onlyseasoned motorsport fans, butalso new, fresh to the scenetechnology enthusiasts.However, while fans arecurrently dazzled by thefantasticdisplayofracingactionand technology excellence, thetime will inevitably come whentheytoowillwantatasteoftheaction.
Motorsporthasalwaysbeencharacterised by its entry-levelformulae. These classes havealways been there, feeding thebigger classes by providing astage for new talent to developand show itself to team
managerseagertosignthenextchampion. Not only that, butlower formulae are also whereracing enthusiasts can emulatetheir idols. Eitherway,both theaspiring professional driver andthe hobbyist have theopportunity to race alternativeversions of the desired andadmired racing cars of higherformulae.
Despite the less advancedchassis and the smaller enginesmaking for slower, and moreimportantly, safer cars they arestill capableofputtingeveryoneon the edge of their seats withclose racing action and highlydisputed contests. Single makechampionshipsexcelinprovidingraceaction largelyasa resultofevery driver on track havingaccess to the same equipment.Not only does this format lenditselftoexcitingracingthatbothfansanddriverslove,butitdoessoatasensiblecost–foregoingthe need for expensivetechnological developmentessential to success in openformulae.
The question is, where canthe electric vehicle enthusiast
find their share of the action?Where is the starting formulathat allows the fans to have atasteofwhatelectricracingisallabout? The answer to thesequestions is currently beingdeveloped at Oxford BrookesUniversity(OBU)incollaborationwith one of the world’s largestracing car manufacturers:DallaraAutomobili.
PluggingthegapBack in 2014 the OBU
Department of MechanicalEngineering and MathematicalSciences received a visit fromAndreaToso–HeadofR&DandUS Racing Business Leader atDallara. This visit would kick-start a project that will fulfilelectric racing dreamseverywhere.
FIGURE1
OBU’s impressive facilities -which include equipment suchas a Scanning ElectronMicroscope, 4 enginedynamometer test cells, a windtunnel, and a 4 Post dynamictestrig-enticedAndreatovisit,
but it was rather the expertiseand the culture of attention todetail embedded within OBUthatimpressedDallarathemost.The signs are everywhere, fromhaving one of the top UKFormula SAE teams, strongindustrial partnerships and therecognitionofthetalentofOBUgraduates from leadingmotorsport and automotivemanufacturers.
Dallara quickly recognisedthe clues that pointed to theability to conduct a successfulambitious project and sodecidedtomakeamove.
Having recognised a gap inthe market Dallara, themanufacturerofeveryFormulaEcaron thegrid, approached theDepartment of MechanicalEngineering and MathematicalSciences with the idea ofdevelopinganaffordableelectricracingvehicle.
The challengewas promptlyaccepted and so started one ofthemost ambitious projects forOBU: The Formula Club-EDevelopment Project. Everydetailofthevehiclefromchassisdynamics, powertrain options
down to the formula andbusiness model were to bedeveloped by Oxford Brookes’MSc students guided at everystepof thewaybyexperts fromDallara.Toensurethesuccessofthe project at all levels themotorsport vehicle designexpertise of the Department ofMechanical Engineering andMathematical Sciences wassupported by the businessstrategy and developmentknowledge from the BusinessSchool. This breadth ofknowledge coupled with thechance to work on a real, largescale project provides anexcellent learning opportunityfor the students, and cruciallyprepares them for employment.TheDepartment isverykeenonthis-92%ofgraduatesgoontoemployment; many in F1,Formula E and other majorsuppliers to the automotiveindustry.
The project is scheduled for4 years and is now mid-waythrough completion. More than100 postgraduate MSc studentswillhavecollectivelycontributedover 60,000 hours for thesuccess of this project by theend of the fourth year. Thenumbers alone show thecommitment and ambition ofthisinstitution.However,it’sthequality of their work that reallyshowswhytheywerechosenforsuch an important step for themanufacturer - and moreimportantlyformotorsport.
ElectricfencestojumpThe design, manufacturing
and commercialisation of avehicle and racing series is achallenging task at the best oftimesanditonlybecomesmoredifficult when the vehicle inquestion is electric. Plenty oforganisational and engineeringchallenges arise in this area -some from the lack ofknowledge and experiencewiththe electric powertrain, somefrom the uncertainty of thecustomers’ reaction to atechnology in its relativeinfancy.
The Business School helpedto support the difficult task ofcharacterising the market anddetermining thebusinessmodelmost likely to succeed. Athorough analysis ofconventional seriesandvehicleswas performed to positionFormulaClub-Einthemarketasattractivelyaspossible.
FIGURE2
The performance of electriccars is largely unknown whencompared to their internalcombustion counterparts, andthere is a serious concernregarding the safety of thesesystems - with carefulprecautions being taken at thisstage.
The level of detail of theanalysis undertaken highlightsthecommitmenttothisproject-making it impossible to ignorethis as a serious bid for thefuture of affordable electricracing.
Defining the winningFormula
The possibilities that arisefromstartingwithablanksheetcan soon turn into aconceptually confusing productifcareisnottakentodefinetherightgoals.OxfordBrookesisalltooawareofthisandveryearlyin the project started to definethecharacterofthisvehicle.
Developed for a lessexperienced or even amateurgroup of drivers the drivingexperiencehadtobesimplified.All toooftennowadays cars areequipped with so muchtechnology that the drivingexperience is diluted by thedevices implemented to makethe car faster. Even though thelowest lap time may be theultimate goal for some othersare discouraged by all theexperience, preparation andbudgetthatafastcarrequires.
With this in mind theFormula Club-E is meant to
feature the very latesttechnology and yet befundamentally simple. Focusingon the enjoyment of the driverat manageable speeds for theless experienced. Regardless ofhavinga clear ideaof their goalOxford Brookes could not riskgetting this formula wrong. Assuch, not only weremost ideasconsidered - they were fullydeveloped and tested. Thisapproach eliminates any doubtsthat the final design will beanythingotherthantheoptimaldesign.
Itisimportanttorealisejusthowcomplexastudylikethisis.Every parameter tested iscoupledwith at least one otherareaofthevehiclemakingthisamulti-dimensional problem ofoptimisation. The cooperationbetween groups of differentdevelopment areas isparamount.
FIGURE3Simulatingthefuture
None of this would bepossible without extensive useof simulation tools. Startingfromasolidbaseofexpertiseinvehiclesimulationandmodellingthe Department of MechanicalEngineering and MathematicalSciences continues to push forbetter, faster andmore reliablesimulations. DYMOLA wasadopted as a tool to build theadvanced ‘virtual prototype’models required. Uponcompletion and assembly of alltheindividualmodelstestingwillbe undertaken at the state ofthe art Dallara Driver-in-Loopsimulator, allowing test driverstoexperiencethevehiclebeforeit comes to reality as a physicalproduct. Feedback on thevehicle performance can begathered and improvementstried before production costsareincurred.
FIGURE4
One of the areas whereknowledge is evolving themostis undoubtedly the powertrain.The motor and batteries arelarge, expensive, heavy andcrucial components that requirethe upmost care when beingspecified.OneofthebenefitsofFormula Club-E will be to helporganisations like Tesla raisepublic awareness andacceptance of electric vehicletechnology–thoughithastoberecognised that significantchallenges for mass take-up ofthe technology exist in thesupplychain,suchasthesupplyofrareminerals.
After considering torquevectoring strategies, a singlemotorwasdeterminedtobetheideal solution in view ofefficiencyandcostcontrol.Mostsuitablemotoroptionsavailablein the market have beensimulated.However,sincethisisaconstantlyevolvingtechnologynew solutions are always beingconsidered when they becomeavailable.
As far as powertrainperformance is concernedcurrently the biggest limitingcomponent are the batteries.With around 1/30th of theenergy density of petrol theymake up a large portion of thevehicle mass. Furthermore, therequirements for batteries inmotorsport are also veryextreme with very high powerdraw and charge making foraggressive usage cycles. Thebatteries need to be chargedquickly between races, and alsoabsorb and store the energyfromregenerativebrakingwhileinuse.
Within this area, there aresignificant materials sciencechallenges - but the constantneed inmotorsport topush theboundaries of performancemakes it the ideal test bed forthe development of materialsand disruptive newtechnologies.
The importance of choosingthe appropriate batteriesbecomesevenclearerwhenonerealises that the team evensimulate where and how thevehiclewillberaced.Thisisdueto different energy levels andconditions encountered atdifferentlocations.
Keepingitsafe…Due to vehicle dynamic
considerations and the amountofmass involved batteries haveto be placed in a location thatwill place the centre of gravity(CoG) in a favourable location.When it comes to the influenceof the CoG on the dynamicbehaviour of the vehicle, themore central and lower theposition the better. Althoughusing a battery composed ofcells can allow for somefreedom in configurations thereis one major aspect thatsomewhat limits thecreativity–safety!
FIGURE5Motorsporthasbeenmaking
hugeeffortstoensurethesafetyof the drivers, marshals andpublic. Electricbatteriesarenotnecessarily any more or lessdangerous than a full tank offuel, but battery specificconsiderationshave tobe takenintoaccount toensure the levelofsafetyrequired.Thespeedatwhich the energy stored caninflict severe injuries makescontaining that energy in theeventof an accidentoneof thebiggestpriorities. In viewof thepriority for safety, thearrangement of the cells hasbeen kept in amore traditionalconfiguration, which in turn ledto a solution that consists of asingle unit containing all thecells behind the driver. Eventhough it may be more
detrimental to the vehicledynamicsthanamodulardesignthatcouldbespreadaroundthedriver, this solution is morerobust, andmore likely tomeetsafetyregulations.
Crash scenarios have beenconsidered and simulated toanalysethestructuralbehaviourof the system, andinstantaneous shut-off circuitsrelying on monitoring of powerusage and demands have beendeveloped. The crashsimulationswereruninLS-DYNAfollowing FIA guidelines forsafetyrequirements-onceagainhighlighting the attention todetailemployedthroughoutthisproject.
In fact, having so manybright minds on the case hasevenallowedOxfordBrookestoprepare the vehicle for futuretechnologies and regulations.Should there be a need for it,and permission from regulatorybodies, the Formula Club-E isdesigned to allow for batterychangesduring the race, in true‘refuelling’ style. The safetychallengesherearesohighthateven thepinnacleof the sport -FormulaE,hasoptednottouseitforthetimebeingongroundsofsafety.Asaconsequence,twocarsperdriverarerequiredwitha change of cars mid-race. Thesame scenario would not besustainable for a low budgetformula.
To incorporate a removablebattery design Oxford Brookes’students have not only to copewithexistingchallengesbutalsowith theones thesolution itselfcreates. In other words, fromthe moment a battery pack issealed, in order to guaranteesafety, something else becomesa hot topic – temperaturecontrol.
FIGURE6
…andkeepingitcoolMotorsandbatterieshavea
temperature window ofoperation relatively small withexponentially decreasingperformance when operatingoutsideof range. If controloverthe temperature is lost thedamage can build up to severefailures of the system. Notleavinga singledetail tochancea considerableamountof efforthas been made to understandtheheat transfer interactions inplace. Extensive thermalcomputational fluid dynamics,finite element analysis andDYMOLA simulations wereperformed, with expert training& support in the use of thesoftware provided by ClaytexServices. Many hours ofmodelling work later, asimulationcapableofcalculatingreal-time componenttemperatures was completed.Thismodelwill be oneofmanyrunning simultaneously in thedriver-in-loop Dallara simulatorproviding valuable data with aresolution down to eachindividualbatterycell.
FIGURE7
Currently simulations arebeing carried for charge/dischargecyclesforthedurationof the whole event, includingtrack driving, energy recoveryandbattery rechargingwith thevehiclestationary.
MorethanaconceptThe scale of the project
coupled with meticulousanalysisthatisbeingundertakenin Oxford Brookes and Dallara’sFormula Club-E project conveysa sense of purpose - ofsomethingthatwillnotsettleforbeingamereconcept.
FIGURE8
Currently at the midwaypoint the project has a fewquestions to be answered andcomponentstobefinalised.Thesimulation models developedare prepared for this, andalternative emergingtechnologiescannowberapidlysimulated and evaluated, thustheteamareactivelylookingforpartners to help contribute tothe project. In fact, they havemuch industrial support for theproject, including some famousnames such as David Brabham,AllanMcNishandPetterSolberg.If you would like to add yourname to the list the team areinviting people to [email protected]“Dallara”.
The answer to budgetelectric racing is coming - andnotsurprisingly-bythehandsoftwoworld leadingorganisationsin Motorsport engineering:Oxford Brookes University andDallaraAutomobili.
AuthorsMiguelFernandezFerreira–TechnicalInstructor,DepartmentofMechanicalEngineering&MathematicalSciences,OxfordBrookesUniversity
AndrewBradley–SeniorLecturer,DepartmentofMechanicalEngineering&MathematicalSciences,OxfordBrookesUniversity
AndreaToso–HeadofR&DandUSRacingBusinessLeader,DallaraAutomobili
GarethNeighbour,HeadoftheDepartmentofMechanicalEngineering&MathematicalSciences,OxfordBrookesUniversity
FIGURE1
AndreaToso,HeadofR&DandUSRacingBusinessLeaderatDallaraAutomobili,sharesdesignideaswithOxfordBrookesStudents
FIGURE2
Marketsurvey-Iselectricracingthefutureofmotorsport?
StronglyAgree15%
Agree39%
Disagreebutcouldbeconvinced
31%
StronglyDisagree15%
FIGURE3
Modulardesignallowsforeaseofmaintenance
FIGURE4
Dallara’sDriver-in-LoopSimulator
Figure5
Analysisoftheweightdistributionofthevehicle
Figure6
CFDanalysisofthecoolingsystemfeedsthethermalmodelsinDYMOLA
Figure7
Thermalmodelsofthebatteryallowindividualcelltemperaturestobemonitoredinreal-time
Figure8
Speedprofilesforvariousmotorchoices
Spee
d [k
m/h
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Time [s]
Motor I Motor II Motor III Motor IV Motor V
