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TECHNICAL COLUMNPerformance, racing and tuningwith Ray BrownThe global participation, audience and market associated withperformance, racing and tuning is huge. In this article we willexamine some of the basics and newer technologies, which influenceperformance and safety on the track and road.A myriad of regulations controllingmotorsport and road vehicle modificationsprecludes any specific commentaryassociated with a particular vehicle brand,type or class but many of the principlesdiscussed still apply.WeightsOn a vehicle, everything is a compromisesuch that when you change one thing, or asystem, it affects at least one other thing orsystem.Weight however, is the one thing that canhave an affect on all operational parameters.Obviously a lighter vehicle can acceleratefaster than a heavier vehicle with equaltraction.On the other hand, a heavier vehicle mustuse more energy than its lighter equivalent, toslow down or decelerate.In cornering the heavier the vehicle, moreenergy must be absorbed by the tyre inchanging direction.Of course these are the primary impacts ofvehicle weight, but the secondary effects arejust as important.For example, in a lighter car the stressesplaced on its structure during acceleration,braking and cornering will be less, andtherefore there is scope to reduce or changematerials accordingly, which results infurther weight reductions.This ‘optimisation’ of vehicle weight,performance and durability is a majorfocus of Formula One (F1) teams.Most F1 cars weigh in the vicinityof 440kg whereas their minimum raceweight is just over 600kg includingdriver and fuels.The difference is accounted forby adding ballast to the car, whichmeans that teams can tune thecentre of gravity of the vehicle tofurther optimise vehicleperformance.The principles of weight savingsto the vehicle also apply to the majoroperating systems within the vehicle.For example an engine uses asignificant amount of its power toaccelerate its own components, so logicallyif the moving parts can be made lighter thenmore energy will be available to power thevehicle.Within the suspension system, a lower‘unsprung mass’ enables the wheels to stay incontact with the road surface more efficientlyimproving cornering and braking capabilities.AerodynamicsThe total aerodynamic package of the racecar is now more important than ever.Race teams that plan to stay competitiveuse wind tunnels and track testing to developthe most efficient aerodynamic design.The focus of their efforts is on downforceand drag. Downforce is necessary formaintaining speed through the cornerswhereas drag, which accompaniesdownforce, will slow the car.The efficient design of a chassis is basedon a downforce/drag compromise such thataerodynamic improvements are directed togenerating downforce on the race car with aminimum of drag.FIG 1: Bell HP3HelmetThe principles, which allow aircraft to fly,are also applicable in car racing.The wing of an aeroplane is shaped so thatthe air moving over the top of the wing movesfaster than the air beneath it.Since the air pressure under the wing isgreater than above the wing, lift is produced.The shape of a race car chassis is similar toan upside down aerofoil.The air moving under the car moves fasterthan that above it, creating a downforce ornegative lift on the car.A race car travelling at 300kph cangenerate downforce that is approximately twiceits own weight.Specific race circuits place differentdemands on the aerodynamic set-up of the car.For example a road course with high speedcorners requires a car set-up with a highdownforce package to maintain speeds in thecorners and to reduce wear on brakes.A speedway circuit, similar to those usedby NASCAR, is very different.Drag is not linear; when the speed of a racecar doubles the drag actually goes up by afactor of four so drag reduction is far morecrucial for this type of circuit.Everyone is aware of the benefits of ‘slipstreaming’ where, by driving closely behind thecar in front, the aerodynamic drag is reducedrequiring less engine power and thus savingfuel.What is less well known is that ‘slipstreaming’ also benefits the vehicle infront.When a car is running alone it creates avacuum behind it, which creates a higherdrag.During slip streaming the car behindfills that vacuum resulting in less drag forthe front car. The benefit of two carsrunning together can increase maximumspeeds by around three percent.SafetyHelmetsFelipe Massa’s recent accident inHungary, when a spring from a Brawn vehiclebounced down the road into Massa’s helmetat around 240kph, brought the question ofF1 helmet design into the spotlight.22 AU T O M O T I V E A F T E R M A R K E T M AG A Z I N E F E B R UA RY 2 010 www.aaaa.com.au
TECHNICAL COLUMNBut there is little doubt that the injurywould have been much worse had Massa notbeen wearing one of the latest FIA 8860-2004 standard helmets compulsory for all F1and many other (including V8 Supercars)motorsports.The development objectives for this newhelmet was to make it 50 percent stronger,whilst reducing weight, and limiting thestrains on a driver’s head and neck whensubjected to high G impacts.The basic design consists of a hardouter shell and an energy-absorbing innerlining.The outer shell is made up of layers ofT1000 aerospace-grade carbon fibrematerial.Beneath these are sheets of aromaticpolyamide, which are strong and heatresistant which were first developed formilitary body armour.The different fibres are bonded togetherusing resin being baked at high pressure andtemperature.The inner liner function is to bring thehead to a stop as gently as possible and thisis achieved by using a combination ofdifferent density lining materials.The outer shell works if it flexes a littlewhen hit, rather than crushing ordelaminating.This helps to reduce the G-forces insidethe helmet.The use of lightweight materials meansthat these helmets can weigh as little as1300 grams but can withstand astonishingforces.The Bell HP3 was the first helmet to meetthe FIA 8860 - 2004 standard.HANS DeviceThe HANS device is a head and necksupport, which is compulsory in most carracing sports.Primarily made of carbon fibre, the deviceis something of a U shape with the ‘U’ fittingbehind the back of the neck and two armslaying flat along the top of the chest andsupported by the shoulders.It is attached to the helmet by twoanchors on either side and not to the safetybelts, driver’s body or seat.The purpose of the device is to stop thehead from ‘whipping forward’ in a crash,without otherwise restricting movement ofthe neck.In a crash the safety harness deceleratesan unprotected body with the headmaintaining velocity until the neckdecelerates it.The HANS device maintains the relativeposition of the head to the body, with thedevice transferring energy to the muchstronger chest, torso and shoulders.Racing SuitsThe latest technology racing suitscomprise of three layers of fabric to maximisefire resistance, breathability and drivercomfort.The outer layer is manufactured from a DuPont registered product called Nomex –developed for US military battlefield clothing-- in combination with carbon fibres tomaximise fire resistance in an ultralightweightfabric.The superior insulation properties ofNomex are also used as a felt in the middleFIG 2: HANS Device worn by NASCAR Veteran Ken Schrader.layer to provide a highly effective heattransfer barrier.The inner layer is designed to provide thedriver with comfort with flat seams to improvecomfort at pressure joints.For endurance type races such asBathurst, there are a number of coolingsystems available for drivers to reduce thepossibility of heat stress and fatigue.Veins are sown into the suit so that coldwater from a refrigeration unit can circulateremoving excess core body temperature,cooling and relaxing the driver in hotconditions.For endurance type racessuch as Bathurst, there area number of cooling systemsavailable for drivers toreduce the possibility of heatstress and fatigue.Kinetic Energy Recovery Systems(KERS)This technology was introduced for thefirst time in F1 in 2009 and is underconsideration by other motorsport bodies.KERS is simply a regenerative brakingsystem, which converts some of the wastedenergy of braking into another form whichcan be used to give a car a ‘boost’ of power.The current FIA rule allows maximumstored energy sufficient for drivers to use60KW (or roughly a 10 percent increase inengine power) of ‘boost’ for 6.6 seconds perlap.According to Williams the current rule isworth about 0.3 seconds per lap but thisbenefit will increase as FIA increases thepower and energy available in forthcomingseasons.Currently there are two types of KERSunits being used by F1 teams.Electronic KERS – This system has anelectric motor/generator mounted within thedrivetrain.During braking a proportion of therotational force is converted by the generatorto electrical energy which is stored in alithium-ion battery or a super capacitor.When the driver pushes the ‘boost’ buttonthis stored electrical energy powers theelectric motor unit.Mechanical KERS is a system that uses aspecial flywheel to store energy. The flywheelAU T O M O T I V E A F T E R M A R K E T M AG A Z I N E F E B R UA RY 2 010 23
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