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RICARDO QUARTERLYREVIEW

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BUGATTI VEYRONSPECIALRicardo supports Bugatti to design,develop and manufacture the driveline forthe Veyron – the world’s fastest road car

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One thousand and one horsepower, sixteen cylinders, seven speeds and over400km/h – transmission engineering challenges don’t come much tougherthan Bugatti’s fabulous million-euro Veyron supercar.Tony Lewin reports onthe support provided by Ricardo in the development and manufacture of oneof the most sophisticated driveline systems ever conceived

“The most advanc e

It’s the front-cover splash of almostevery car magazine in the world.Everywhere, writers are struggling

to find new superlatives to describe itsastonishing performance. Andeverywhere the message is the same:this million-euro machine redefines,dramatically and decisively, our ideaof what a car can do.

The concept of a road car faster thana Formula One car is no longer fantasy

but fact; thanks to Bugatti, thisremarkable display is now seen asachievable with a car that’s alsoelegant, luxurious and refined, andwhich does not demand racing-driverskills at the wheel.

Bugatti has defied the doubters andproved that 400 km/h and first-classcomfort can indeed go together. Yetwith expectations so suddenly and sodramatically transformed, it is all too

easy to forget what a monumentaltechnical achievement the Veyronrepresents. It is especially important torecall that, at the time it was originallyproposed in 2000, the idea of the 1001horsepower sports car seemed a nigh-on impossible technical challenge.

VW chief astounds the industryA moment of stunned silence grippedthe audience of international

Bugatti Veyron

08 RICARDO QUARTERLY REVIEW • Q2, 2006

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ed car of our time”automotive journalists as the crowd ofnormally talkative reporters choked indisbelief at what they had just heard.The scene was the Nogaro HiltonHotel in Geneva in March 2000, whencorrespondents had assembled tohear Volkswagen’s then CEO, DrFerdinand Piëch, deliver his annualstate-of-the-union address to theworld’s business and technical media:in the middle of a long stream ofcorporate results, sales predictionsand bland technical statistics, Dr Piëchhad casually tossed in the numberwhich was to astound everyone – onethousand and one horsepower.

For this, said Dr Piëch, would be thepower output of the new BugattiVeyron sports car. Only the absoluteultimate in power, performance andsophistication would suffice for the

21st century revival of what had in itsheyday been the most glamorousmarque in the world. “This will be themost exciting and most advanced carof its time, no more, no less,” hepredicted.

Previously, only a select few racingcars had breached the thousand-horsepower mark. It would clearly be amajor technical challenge to feed thispower to the road safely enough fordrivers with standard rather thancompetition licences: delivering suchstupendous performance with thesmoothness and refinement demandedby an elite millionaire clientele waslikely to be a bigger issue still.

Bugatti’s HeritageIt is difficult from today’s perspectiveto imagine the awe in which the

Bugatti marque was held during its1920s and 1930s golden age. Its sportsand racing cars were engineered withabsolute purity of focus, always light,ingenious and elegant; the integrity ofthe road-car chassis attracted the verybest coachwork builders of the era,producing style landmarks such as theAtlantique coupé and, at the oppositeend of the scale, the mammoth Type41 Royale. In its exotic aura Bugattiwas the Ferrari of its time, but with theequivalent of Rolls-Royce luxury,radical thinking from Lotus and hard-wired race heritage from McLarenthrown in too.

Undeniably, the task ofreinterpreting this unmatched legendfor the 21st century customer hasbeen a daunting one. Accordingly,Volkswagen decided to call upon the

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1250 Nm of torque, but also forautomated shifting and electro-hydraulic control of all key functions.The driveline, too, was to be ofexceptional complexity, with drive toall four wheels, an innovative activerear axle, a Haldex coupling built intothe front axle, and all the electronicand hydraulic control systems to

determine not just straightline tractionbut high speed vehicle dynamics too.

What at the beginning was simplyan outrageously fast pure sports carsoon found itself doing double duty as


Bugatti Veyron

very best skills on offer among theworld’s automotive engineeringproviders to ensure the born-againBugatti would satisfy theextremely high demandsplaced on it by customerswhose automotiveportfolios already includethe likes of Bentley,Ferrari, Porsche andMercedes-Benz.

For the embryo Bugattidivision, set up underVolkswagen’s Wolfsburgroof pending thecompletion of the BugattiAtelier at the marque’sfamous Molsheim homeacross the border in France,Ricardo was the natural choiceof engineering partner for thetransmission and driveline system.

Michael Kodra, Bugatti engineer incharge of the liaison with Ricardothroughout the programme, explains:

“We had already worked withRicardo on smaller programmes – theybuilt the axles for two different showcars that were presented, and theseaxles worked perfectly and without anyfurther problems. We also needed acompany which could supply us with agearbox at low volume: most of theother big gearbox suppliers are seekingto make money through volumes, andwe can only offer a run of about 300.Thanks to this and our previousexperience with them on the W18 andW12 sports car, we decided thatRicardo would be the best company tosupport us on this job.”

Ricardo’s biggest-ever drivelineprogrammeThough Ricardo enjoys anunparalleled reputation in the field ofultra high performance transmissionsystems across both sports and racingcars (providing drivelines for theJaguar XJ220, McLaren F1 and Audi’sLe Mans winners, for example), oncethe specification of the Veyron wasrevealed it soon became clear that theBugatti transmission system would bemuch the most sophisticated thecompany had ever built. As a result,the programme would be the largestever supported by the company’sdriveline and transmission engineers.

Bugatti’s brief called not just for aseven-speed dual clutch gearboxcapable of handling an unprecedented

With seven speeds, dual clutches, four wheel drive and an active rear axle,the Veyron driveline (right) is one of the most complex ever bulit

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a much moreluxurious, more

Bentley-like vehicle –while of course retaining

all its daunting performancerequirements. Attaining all

these demanding design goals,many of which would

conventionally be seen as totallyincompatible, was a major

achievement by Bugatti and all the

companiessupporting theVeyronprogramme.Yet, at thesame time,the fact thatthe Veyron

programmebecame part of

the mainstreamVolkswagen

product developmentprocess provided what

was to be the most challengingtask of all.By bringing the Veyron ‘in-house’,

Bugatti’s new technical director, Dr Wolfgang Schreiber, ensured thewhole vehicle met the same dauntingdurability targets that would normallybe fulfilled by standard million-a-yearGolf-platform family cars – modelswhich have to perform faultlessly inservice over many years of hard use.Prior to the arrival of the Veyron, thenormal life expectancy for a raresupercar was frighteningly short, withnumerous pit-stops and replacementsystems required at frequent intervals.What Schreiber prescribed wasmassively more demanding than


anything ever seen among normallyfragile supercars.

The durability requirements maketruly terrifying reading for anyengineer with an ounce of mechanicalsympathy. Given that much of its50,000 km is driven with thethousand-horsepower engine at fullthrottle, the Veyron’s transmissiondurability programme must rate asone of the toughest the auto industryhas ever devised.

Mike Everitt, senior programmesmanager at Ricardo, believes that thisregime makes the Veyron thestrongest ultra high performance carever built. “Wolfgang Schreiber hasgenuinely shifted the goalposts in thesupercar segment,” he says.

Big-name supercars all too oftenprove fragile in service. It is rumouredthat one model is only capable ofdoing three full-bore launches beforethe clutch needs to be replaced. TheVeyron, on the other hand, completed200 consecutive full-throttle launcheswith consummate ease. “The testersonly stopped because it was gettingtoo dark,” remembers Everitt. “Theclutches were still fine.”

“When exposed to the full 1,250 Newton-metres torque of the 16-cylinder engine, the resistance of the air and even the force ofgravity itself seem to have no chance: the EB 16·4 Veyron eats upthe road as if these physical laws had just been abolished”

Bugatti publicity, 2003

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brings home the scale of the multi-national Ricardo and Bugatti drivelineteam’s achievement. There are nofewer than 660 part numbers for thedriveline’s 1200 components and thesystem breaks new engineeringground – particularly in its use ofseven forward speeds and twinclutches, and in its real-time role indetermining high speed vehicledynamics through its active reardifferential and Haldex coupling.

The use of ADAMS simulationmodelling of vehicle dynamicsallowed Ricardo to provide Bugattiwith much necessary data to developand optimise suspension kinematics,to fine-tune the car’s drivingcharacteristics and present a range ofoptions to Bugatti management.

“Bugatti engineers determined whatthe preferred calibration was to be,”says Mike Everitt. “They have beenhighly successful in calibrating the carin precisely the desired manner, withour assistance. We have helped themgive the Veyron the character theywere looking for.”

Driving the VeyronAs a key figure in the Veyrondevelopment process, Mike Everittwas familiar with the astonishingabilities of the 16-cylinder Bugatti longbefore the international press wasfinally allowed access to the car inSicily in October 2005.

While the assembledcorrespondents were excited, effusiveand often emotional in theircomments, Everitt retains the level-headed detachment of an engineerprofessionally reviewing a technicalmission successfully accomplished.

Complex though the transmissionhardware undoubtedly is, he says, the

“

”

MICHAELKODRA Michael Kodra isthe Volkswagengroup engineer incharge of liaisonwith Ricardo andother key suppliers

Did the experience with Ricardogearboxes on the Audi Le Manswinners influence your choice ofdriveline partner?No. We started this programme justbefore the Audi programme becamepublic. Ricardo always keeps itsother customers secret, so even weat VW did not know that this workhad been done for Audi in the racecars.

The driveline for this car is verycomplicated and has a huge effecton the handling and drivingcharacteristics of the whole vehicle.How is it that VW can work togetherwith an outside supplier when it isreally determining how that vehiclewill drive?Using the knowledge we havegained through working withRicardo we have implemented thecorrect features into the car, such asthe rear axle differential, theelectronic/hydraulic control, theHaldex coupling which enables us tohave four wheel drive, and this dualclutch gearbox. We have been verysuccessful in learning how tocalibrate and to optimize them.

What about the active reardifferential?At that time the rear differentialcontrol was something VW hadnever had in its ordinary cars: wewere about to introduce it in theTouareg luxury SUV. This isdefinitely an item where weneeded to have a close look andliaise with these [Ricardo] guys in their work. On the gearbox side, we have done the same gearbox, though much smaller and lighter, for our ordinary passenger ranges such as the Golf. Here, Ricardo learned from VW concerning some software strategies and so on. So I think we both share a little bit, we both learn a little bit.


Bugatti Veyron

Design, development andmanufactureThe complexity of the driveline and itscontrol system was such that MikeEveritt and his colleagues at bothRicardo and Bugatti had to bring inextra engineers to ensure theprogramme would keep to the verydemanding schedule set by Bugatti: atits peak, Bugatti’s engineering teamwere supported in the programme byover 50 Ricardo driveline andtransmission engineers, with a further12 -15 electronics specialists workingon the transmission control systemand additional engineers in vehicleengineering too. Two Ricardoengineers even took up residence inVW’s home city of Wolfsburg.

“One mustn’t forget the absoluteenormity of the task that facedBugatti,” explains Everitt. “It designeda car that’s not only the fastest andfastest-accelerating car in the world,but one which is technically far moreadvanced than any of itspredecessors.

“It has far more features in it,”continues Everitt. “It’s four-wheeldrive, it is turbocharged, it has anactive differential and an active drivetransmission system with dualclutches. The car is very sophisticatedand is entirely new: new engine, newdriveline, new chassis, new everything– and it’s attacking the market as themost prestigious sports car ever built.It has been a very formidablechallenge.”

Even a quick glance at the cutawayof the Veyron driveline on page 10

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key throughout is the software thatcontrols it – even though the driver isunlikely ever to sense it doing its job.

Yet even Everitt cannot resistbeaming broadly as he revels in theexperience of driving the sixteen-cylinder, 400 km/h machine:

“If you are driving the car you justpull a lever and all you see or sense(of the gearshifts) is that the revcounter needle falls or rises: it is slickand smooth but in the backgroundthere are a dozen valves controllingkey parameters, changing clutchpressures, shifting which gear isengaged and which is the next pre-

selected gear and so on.”One of the key challenges of the

gearbox is that it has, on VW’sinsistence, a non-interlocked gearselection system. This enables super-fast shifts but, in contrast toconventional gearboxes where it isphysically only possible to engage onegear at a time, the mechanicalarrangement of the Veyron box makesit theoretically possible to engage upto four gears at once. It is a vital taskof the control software to ensure thatsuch a damaging occurrence cannever happen, and to this end Ricardospecified twin control networks, eachrunning on different software codes,written by different teams usingdifferent methodologies. The task ofthe first is to control the transmission,

R icardo is no stranger to low-volume, high precision transmissionmanufacture: its workshops have witnessed the assembly not only of the

drivelines for the McLaren F1, Jaguar XJ220 and Volkswagen W12 Nardo recordbreaker, but also five years of Le Mans winners for Audi and numerous othersuccessful but less well known products. Even so, such is the importance ofBugatti and the complexity of its driveline that a whole separate area of theRicardo transmissions facility is dedicated exclusively to the assembly of theVeyron system.

Conditions in the Bugatti assembly area are akin to those of a scientific cleanroom, with each of the driveline’s 1200 components receiving a three-stagecleaning process – culminating in an ultrasonic phase – before assembly.Component tolerances are close to aerospace levels at 6-8 microns, and exoticmaterials include rare-earth magnets located on the gear selector forks forextremely precise position sensors mounted on the external casing to monitorthe exact location of selectors. This information is used in the control strategyand helps rule out double gear engagements.

“This is a very high quality, and clearly very high cost operation,” says AdrianTurner, manager of Ricardo’s low volume production operation, of themanufacturing process. “It’s more akin to an advanced prototype build thanseries production – we call it dedicated cell manufacture.”

The cell system sees two technicians each assemble a single transmission aweek. Each stage of the assembly process is meticulously documented, withthe technician confirming every operation, measuring every tolerance andcritical dimension and noting the thicknesses and positions of all shimsemployed. The multi-page document is held in the Ricardo database so that anyin-service problems can be traced back to individual parts of known history.

while the second continuouslymonitors it to double check that adouble engagement is not about totake place.

Surprising though it may seem for acar of such phenomenal performance,the concept of everything workingfaultlessly and seamlessly in thebackground is an important part of theBugatti’s make-up – again making apotent contrast to supercarcompetitors which can be famouslytemperamental and tricky to drive.

Mike Everitt describes it as silkysmooth and easy. “When the caraccelerates it is so fast that if you havea clear road in front of you and youcan accelerate up to 150 mph (240km/h) – which it will do in a matter of afew seconds – it will be up to fourth orfifth gear and you really didn’t evencount them.

“If you are not watching the geardisplay change or watching the revcounter needle change, if you’re justlooking at the road and get to 150 mphand back off, you won’t actually knowwhat gear you were in because it doesit so smoothly,” he enthuses. “Even ifyou were in manual mode, if you don’tdo anything the transmission will shiftup for you anyway when you reachmaximum revs.”

Step-change for VW engineeringFrom the customer side, VW liaisonengineer Michael Kodra is open inacknowledging that Ricardo’s expertisehas been invaluable:

“I think that by being able to bringthis car to the market with its drivingbehaviour every bit as [good as] weexpected it to be, we have done a verygood job. Using the knowledge wehave gained we have implemented thecorrect features into the car, such asthe rear axle differential, theelectronic/hydraulic control, theHaldex coupling which enables ushave four wheel drive, and this dualclutch gearbox. We have beensuccessful in achieving a goodcalibration and optimisation of them.”

“The toughest part in mostprogrammes is always the timing,”explains Kodra. “Right from thebeginning of this job we had a verytight timetable to get this car intoseries production. You need toremember that almost all thecomponents of the car are brand new– the monocoque and suspension, acomplete new engine, gearbox andaxles – all the systems have neverplayed together in one car. We had thistimetable because the car was

MANUFACTURING THE VEYRON DCT


Left: Complex seven-speed dual clutch gearboxtakes one week to assemble at Ricardo’sprecision manufacturing facility

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Zothecas conubium santet lascivius fiduciasuis. Pessimus utilitas cathedras spinosus

presented quite early on, but as aprototype car.”

Such striving for engineeringperfection is of course precisely whatthe Bugatti marque stands for. MikeEveritt cites the example of thesignificantly raised durabilityrequirements applied from 2004onwards: new gear tooth designswere employed to ensure they couldnot only last the distance, but alsomaintain the level of expectedrefinement at the end of the 50,000 kmdurability test. The new gears solvedthat issue conclusively.

"Nothing is too beautiful, nothing istoo expensive"It was with this idealistic maxim that,almost a century ago, Ettore Bugattifounded the company that, like nonebefore and precious few since, wasdedicated to absolute purity in designand perfection in every detail. And,though in 2006 the stakes are vastlyhigher and the regulations governingautomobiles are infinitely stricter,there can be little doubt that the re-incarnated Bugatti has produced a

“

”

MIKEEVERITTChiefprogrammesengineer MikeEveritt led thework on theVeyron driveline since joiningRicardo in November 2000

Ricardo has a lot of experience in highperformance transmissions. Can youbuild on designs you have done in thepast, or does it have to be completelynew? You have to visualize the project astwo distinct elements, the first beingmechanical and the second thecontrol. For both elements we workedvery closely with the VW/Bugattiengineering team to ensure both thatthey got what they wanted and thatwe could incorporate their knowledgeof specific lessons learned from theirown DCT programme in the VW Golfinto the programme. In terms of the mechanical side it is tosome extent an analytical andformulaic process, but it is heavilyinfluenced by the experience basethat Ricardo and the VW/Bugattiengineering teams possess. Knowinghow the transmission needs to bedesigned for this sort of application,with its very demanding andspecialist environment, is somethingthat few companies have experienceof, but it is ground on which Ricardofeels comfortable.

The control element of this gearboxwas, however, the really innovativeside: there are increasing industry andmarket moves towards dual clutchtransmissions because of the benefitsyou get in fuel economy andefficiency and driver feel. But to dosomething in this area ofperformance was quite a challenge:things that work on a “normal” carsimply don’t just scale up when youget into this class of vehicle.

When you discuss a programme like thiswith a customer, who sets out the basicprinciples? Did VW simply want atransmission for a 400 km/h car?No. VW had some quite firm ideas at afeature level – minimum seven gears,very fast speed of shift and so on. Also,the fundamental layout options possiblewere largely dictated by the definedvehicle architecture, but lots of detailswere not defined at all. This meant forinstance that the gearbox in front and the

rear axle behind the engine was defined,but we explored issues such as whetherthe rear axle should form part of theengine cylinder block or should it beseparate.

Did you know the power and torqueoutputs? Did the very high valuesforce you to think differently?Yes, we knew the power and torque, butonly as headline numbers, and also thewheelbase and the predicted weight. Weknew that they wanted it to be fourwheel drive and that they wanted it to beactive not passive, meaning activedifferential controls and active torquedistribution from wheel to wheel. Mostthings about this project forced us tothink differently.

Is the transmission seven speedbecause with a Vmax of over 400km/h you have to cover such a largespeed range?Yes: it’s also seven speed becausereverse is in there as well, givingeight gears in total, with foursynchronizers and two gears persynchronizer – so that works verynicely. It also gives a nice even gearspacing on a car that will go seriouslyfast. Another advantage we had withthis transmission was that we couldmake first gear tall: this car will do its0-100 km/h dash in first gear.

In terms of the mechanical design ofthe system, is it more like a racing cartransmission than a road cartransmission?No: I wouldn’t say it is like a race cartransmission at all, it is like a race cartransmission in the limited sense thatit uses race car transmission typematerials and very high grade steelsfor the gears and shafts. It is fullysynchronized on all gears includingreverse, and all the gears includingreverse are fully helical rather thanstraight-cut. The emphasis onsmoothness of shift and pull-awaycontrol is absolutely key to the wholenature and character of the car. I think everyone will be amazed at justwhat a pussycat it can be. You canbumble around at walking pace allday long with absolutely perfectcontrol: you have no juddering, nokangarooing, nothing that manysupercars suffer from. It is absolutelythe easiest car to drive in terms of theclutch and transmission as can beseen from the many complimentarypress reports of the car.


Bugatti Veyron

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THE VEYRON IN FIGURES

model of rare distinction and trueengineering integrity – a model whichdoes genuine justice to the Bugattilegend.

Yet, having designed, developedand built what is pretty convincinglythe world’s fastest, most powerful andmost exclusive road car, there is justone cause for regret. No more than300 examples of the Veyron will bebuilt over its production lifespan;

many will go straight into privatecollections, while the remainder arecertain to lead a pampered existencein air-conditioned garages under 24-hour security guard. So, regrettably,only a few elite individuals worldwidewill ever be able to savour the uniqueexperience of 16 cylinders, 1001horsepower and the sensational returnof the most illustrious marque theauto industry has ever known.

Engine: 8.0 litre W16, four turbochargers

Power: 1001 hp at 6000 rev/minTorque: 1250 Nm at 2500 rev/minTransmission: Ricardo 7-speed

dual clutch; drive to all four wheels

Performance: 0-100 km/h: 2.5 sec0-200 km/h: 7.3 sec0-300 km/h: 16.7 sec

Kerb weight: 1950 kg

Veyron speedometer reads up to 420 km/h;left-hand gauge shows horsepower deployed


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