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GASOLINE’S LAST STAND! Aston Martin’s new Le Mans challenger

The underdog hits back with a sports car designed to end diesel dominance

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I N T E R N A T I O N A L

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Accident Investigation

How motorsport learns from its disasters

MINI WRC: the perfect rally car?

750FORMULA BUILD UPDATE

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April 2011 CONTENTS Issue 126

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COVER STORY - Page 14 Accidents are rarely simple. What may appear to be blindingly obvious may have no bearing on the true cause”

Accident investigation How motorsport can learn lessons from its disasters INDUSTRY NEWS 6

Peugeot to test Hybrid 4 prototype at Le Mans test day; Mercedes ups stake in F1 team; two-car draft controversy rumbles on in NASCAR; World Motorsport Symposium to focus on racecar of the future; Firestone quits IndyCar – but only for a week!

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NEW CARS: ASTON MARTIN AMR-ONE

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Gasoline’s last stand: Aston Martin has designed its AMR-One with the aim of ending diesel dominance at the Le Mans 24 Hours

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INTRODUCTION ISSUE 126

EDITOR William Kimberley

ASSISTANT EDITOR Chris Pickering

CONTRIBUTING EDITORS Pat Symonds John Coxon Steve Bridges Graham Templeman Matt Youson

CONSULTANT EDITOR Mark Skewis

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SIGNPOST TO THE FUTURE – YOUR OPINION MATTERS LAST MONTH I wrote about the possibility of fuel rationing being introduced sometime in the future. Since then, though, fuel prices have risen so dramatically that we are now seeing reports of people learning to drive in a more restrained way or in some cases have sold their car and have taken to cycling, walking or taking public transport.

It is also a moot point that the prices we have “enjoyed” over the last few years will never be seen again. In other words, we are entering a new age of austerity, one that has been brought upon us by the increase in oil prices.

COMMERCIAL DIRECTOR Maryam Lamond

PUBLISHER Soheila Kimberley

Even on a visit to the US in March I noticed a shift in opinion as gas prices are making an impact on the pocket there as well. We in Europe may scoff at the relatively low price of gasoline there, but the increase is hurting everyone there as much as it is in Europe and the rest of the world.

I do think that we are on the verge of entering a new era, one in which motorsport has to be seen to be playing a part. While we are providing entertainment insofar that we are competing for the same pound/euro/dollar that might otherwise be spent on going to a football match, a theatre ticket or a weekend city break, it is not motorsport’s sole raison d’etre. For all Bernie Ecclestone’s ideas of introducing rain sprinklers at circuits to spice up the racing, this is really of minor consequence when looking at the big picture of what motor racing is all about.

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As regular readers will know, we have concentrated on sustainability and the role of motorsport in the wider world as it is a great concern for us and it is with this in mind that we have already set the theme for the next Race Tech World Motorsport Symposium.

Vodafone McLaren Mercedes, our two chairmen for this year’s event in January, we have decided to look further across the horizon. We want ideas discussed at the Symposium to be a sounding board for the governing bodies when setting the regulations for the future.

Evolution of Revolution: the racecar in 2017? The idea is to get everyone to think about the future, to put forward ideas and proposals in a noncompetitive environment. I have already posed this question on the Race Tech group discussion board on LinkedIn and have received a number of interesting replies. I would also like to receive your views direct to me at the magazine.

Would you like a Formula One car to look radically different to what it is today, for example, the Adrian Newey X1design? Do you go along with the proposal suggested by Sergio Rinland in the last issue whereby the downforce of a car is regulated at a specified speed and an open powertrain defined by a restriction on energy consumption? How about Le Mans? Olivier Quesnel, boss of Peugeot Sport, has made it clear that running a hybrid at the 24 hour race this year is not an option. He will only consider it for 2012 if the regulations encourage him to proceed. What, though, would you like to see competing in 2017? A field of hybrids or diesels?

Will petrol still be a viable option?

I am eager to receive opinions so that they can be submitted to Messrs Baretzky and Iley who have kindly agreed to be our chairmen again next year.

Your views are important, so please fire them in to me on william.kimberley@racetechmag.com or else go to our website www.racetechmag.com and put in a comment there.

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Following discussions last month with Ulrich Baretzky, head of engine technology at Audi Sport, and John Iley, head of aerodynamics at

William Kimberley EDITOR

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MOTORSPORTS PROFESSIONAL

NO HYBRID FOR 2011 BUT PEUGEOT KEEPING OPTIONS OPEN FOR THE FUTURE

By Chris Pickering

GENEVA, Switzerland: Peugeot has confirmed that it is considering a hybrid entry for Le Mans 2012, but it will not be fielding one for this year’s event. Speaking to Race Tech at last month’s Geneva Motor Show, Peugeot Sport director Olivier Quesnel outlined the French firm’s position on a possible hybrid entry.

“I hope the technical regulations will encourage the use of hybrid systems,” he said, “but if not we have no interest in doing it. We want to be competitive if we do go ahead; it’s not something we’d do for purely marketing reasons. It’s very complicated and it costs a lot of money, so it must offer a useful advantage [over pure

internal combustion designs].”

One of the key measures of that advantage will be track testing. Peugeot is aiming to test a prototype of the car at the official Le Mans test day later this month on the 24 April and it is here, said Quesnel, that the team will get the best indication of whether a hybrid design is realistic for 2012.

“This technology is more complicated than you can imagine, especially with regards to the battery, so we have to work hard and it will take a long time,” he said. “We want to take our time and be ready when we come with this car next year. First we will try and capture Le Mans again with a pure diesel car.”

Peugeot also previewed the car at the Swiss

show. Known as the 908 Hybrid 4, it uses a lithium-ion battery pack to store up to 500kJ of energy, captured during regenerative braking via a motor/generator unit connected to the rear wheels. It will then release it automatically under acceleration, rather than using a KERS-style push-to-pass system.

It is one of a number of different technologies that Quesnel can envisage coming to Le Mans in the future. “It’s very interesting,” he commented. “I think we will definitely still have diesels, as well as petrol engines, hybrids and maybe even electric cars. As I see it, Le Mans is there to improve technology for the manufacturers and the more options we have the better it will be.” RT

Peugeot wins Sebring – thanks to ORECA SEBRING, FL: Peugeot notched up its first victory in 2011, winning the Sebring 12 hours, the first round of the Intercontinental Le Mans Cup. However, the win came as a courtesy of the ORECA Matmut team, the two works cars delayed due to accident damage and other incidents.

“I think it’s a very historical result for us,” said team owner Hugues de Chaunac. “In the world of long distance races, there are only two huge races to win, the Le Mans 24 Hours and Sebring. We won Sebring, so we now know what we have to achieve in June!”

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LEFT The ORECA Matmut Peugeot was the surprise winner of the Sebring 12 Hour race, beating off the works cars and the Audis (Photo by ORECA – DPPI)

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MOTORSPORTS PROFESSIONAL

MERCEDES AND AABAR INVESTMENT TAKE CONTROL OF MERCEDES F1 TEAM Stuttgart/Brackley, Germany/UK: Daimler together with Aabar Investment PJS has acquired the remaining 24.9% stake in the Brackley-based MercedesBenz Grand Prix from the management team led by team principal Ross Brawn.

Daimler and Aabar together now own 100% of Mercedes-Benz Grand Prix.

Daimler has increased its stake from 45.1 per cent to 60%, while Aabar has increased its stake from 30 to 40%. Aabar is the biggest single shareholder of Daimler AG, with nine per cent. The acquisition is conditional on clearance from the German Bundeskartellamt.

“Daimler and Aabar’s acquisition of the remaining 24.9% stake in Mercedes-Benz

Grand Prix will be a further step in the consolidation and strengthening of our team for the future,” said Brawn. “Motor racing, particularly Formula One, is a very specialised industry, and we are privileged to have such strong and understanding partners as Daimler and Aabar to support our joint ambitions. I remain fully committed to our team for the long-term, along with the management team and all of our employees. We all look forward to the challenge of making our team successful, and proudly representing Mercedes-Benz and the racing tradition of the Silver Arrows.”

“Our acquisition of the remaining 24.9” together with our partner Aabar underlines

our long-term commitment to Formula One, the pinnacle of motor racing and the best international motorsport platform for demonstrating our willingness to compete and our technical expertise,” said Daimler board member Dr Thomas Weber, responsible for group research and development and also chairman of Mercedes Grand Prix. “This step will bring the colleagues from our Formula One chassis and engine groups even closer together and thereby help to develop our team step-by-step into a winning Formula One outfit. We now also fulfill Ross' wish of being in a position to focus wholly on the complex technical challenges of Formula One and on his role as our team principal.”

RT

LEFT Ross Brawn has sold his remaining shares in the Mercedes Formula One team to Daimler and Aabar Investment

EVOLUTION OR REVOLUTION: THE RACECAR IN 2017?

LONDON, UK: What will be the defining characteristics of a Formula One car in 2017? What will an LMP1 car look like when it is wheeled onto the grid at Le Mans in five year’s time? What will be the dominant powertrain in Formula One and Le Mans?

The theme of the next RACE TECH World Motorsport Symposium, that will be taking place on 9/10 January 2012 will discuss the future of the racecar and where it will be in five years’ time. The idea is to discuss the

way forward, embracing new technologies and encompassing current ones.

The idea follows conversations with the two chairmen of the 2011 event – Audi Sports’ Ulrich Baretzky and Vodafone McLaren Mercedes’ John Iley – who chaired the Racing Engine Day and Aerodynamics Days respectively. For 2012, though, to reflect the Symposium’s evolution, the two days will be Aero & Vehicle Dynamics (Monday, 9th Jan) and Powertrain (Tuesday,

10th Jan) with more time being given for open discussions.

If you have views on this subject that you might like to be discussed, please forward them to William Kimberley at william.kimberley@racetechmag.com with “WMS12 ideas” in the subject bar. The person coming up with the best idea/vision, as chosen by the two chairmen and the editor, will be invited as our guest for the day at the next Symposium. RT

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ABOVE Michael Waltrip in the no 15 NAPA Auto Parts Toyota was involved in a bump-draft spin-out that caused an early ‘big one’ in the Daytona 500. (Photo by John Harrelson/Getty Images for NASCAR)

NASCAR NOT AFRAID TO PUSH ON WITH DRAFT

Andrew Charman

DAYTONA BEACH, FL: New, wilder forms of bump-drafting seen amongst competitors in the Daytona 500 on 20 February appear not to have persuaded NASCAR to make any more technical changes to the cars in its Sprint Cup Series.

As reported in our last issue, changes to the nose of the Sprint Cup cars following the 2010 season and a new surface at the 2.5-mile Daytona Superspeedway saw an end to the previously familiar large packs of

leading up to the Daytona 500 NASCAR changed its technical rules four times in a bid to break up the drafting pairs by putting more pressure on engine cooling systems, and to reduce speeds which were routinely sitting above 200mph.

Despite this the 500 itself turned into a race of two-car drafts – team spotters in the grandstands found themselves trying to broker constant deals to find a drafting partner for their driver, while the drivers switched between around a dozen radio frequencies in their cars so as to talk directly to their rivals and persuade them to work together. This confusing radio chatter had some fearing the potential for danger, in that there could be delays in the spotters warning their drivers when a caution occurred.

ABOVE Two-car draft in action during the Daytona 500. Note the damaged noses The race produced a of the leading cars where they had earlier been providing the pushing power to their drafting partners. (Photo: Nigel Kinrade, Autostock for Ford Racing) record 74 lead changes and created a drafting cars created by the horsepowersurprise winner in Trevor Bayne, a rookie strangling carburettor restrictor plate. competing in only his second Sprint Cup Instead, a new phenomenon – the ‘two-car race. But it also saw a record 16 cautions, draft’ – emerged, drivers soon discovering many caused when bump-drafting went that two cars running together with the wrong and the driver in front was spun into second pushing the first were a faster the wall. Top drivers who saw their race combination than being part of a larger hopes ended by such spins included Kyle pack – the previous route to the front.

Busch, Gregg Biffle and Matt Kenseth.

These drafting pairs were soon running Biffle spun out his team-mate Kenseth entire laps or more, and in the week before himself being turned by Juan-Pablo

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Montoya. “There is only so much you can do trying to drive these cars,” Biffle said after the race. “I hurt my teammate four laps earlier the same way.

“You don’t mean to do it but you have to push to stay up with all the cars.”

However, following the race, NASCAR seemed in little mood to make any changes to affect the two-car draft. Speaking three weeks later, NASCAR’s Brian France said that the competition level was up.

“We had 74 lead changes, dramatic racing all the way through. It’s different, but generally speaking, if competition goes up, the races are exciting, we’re going to like it.”

France’s views were no doubt aided by the fact that NASCAR television audiences, which slid throughout the 2010 season, have shown a dramatic jump upwards in the first three races of 2011.

Despite these views, many observers believe NASCAR will make further changes before the next restrictor plate race, at the 2.6-mile Talladega Superspeedway in April.

Here, and particularly when the series returns to Daytona in July, temperatures are likely to be higher, putting more pressure on engine cooling systems. The repeated rule changes in the week before the Daytona 500 rendered defunct much of the pre-season work teams had carried out on their cooling systems.

The two-car draft typically produces wilder racing across more of the track, and with the bump-drafting making engine temperatures more critical, many fear the potential for carnage resulting from sudden engine failures in the middle of drafting battles. RT

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NEW RULES GIVE NASCAR TEAMS FUEL FOR THOUGHT

By Andrew Charman

LEFT Fill her up – the new self-venting fuel can is clearly visible in this shot of the Toyota of Brian Vickers receiving service at Las Vegas on 6 March. (Photo: Lesley Ann Miller for Toyota Racing)

LAS VEGAS, NV: Three races into the 2011 season some teams in NASCAR’s Sprint Cup Series are struggling to adapt to new rules regarding refuelling.

Late last year NASCAR announced revised refuelling rules, introducing new selfventing fuel cans and ending the role of the ‘catch-can’ man – a pit crew member who inserts a can into the rear of the car to catch overflowing fuel signifying that the tank is full. The move improved safety at a stroke removing up to 43 crew members from the pitlane.

The new can has a second clear pipe, which excess fuel vents back up when the tank is full. However, some teams have found it difficult to time when fuelling should be completed, especially as the new system is slower than the old one and fuelling now routinely takes longer than tyre changes.

A full fuel load requires two fuel cans and under the old system the catch can man held the empty can while the fueller grabbed the second one from over the wall. Now the fueller must exchange the new can with the old one.

Drivers who have been used to leaving

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the pitlane the moment the car was dropped off the jack following a tyre change are now having to wait for a signal that fuelling has been completed.

In round three of the Sprint Cup at Las Vegas on 6 March, Gregg Biffle’s Roush Racing Ford suffered from not gaining a full fuel load on pit stops and went from a

race-challenging position to an eventual 28th-place finish.

Team owner Jack Roush later told trackside media that the new self-venting cans do not deliver fuel at a consistent rate. “We can get two gallons in a second out of the can but it’s probably twice that long to get the last two gallons out,” he said. RT

IN BRIEF Chevrolet has decided which road car model it will base its NASCAR Sprint Cup contender on when new cars are introduced in 2013 – but will not reveal it yet. Rumours suggest that NASCAR’s most consistent winning brand may not choose the Camaro for its new car, as widely predicted. Ford is widely thought to be dropping its current Fusion model in favour of the more performance-orientated Mustang.

German giant Volkswagen has moved to dismiss rumours that it is to follow Toyota as the second non-US manufacturer in NASCAR Sprint Cup racing. Ulrich Hackenberg, head of technical development

at Volkswagen, said no NASCAR programme was planned, adding “I should know what I am talking about, since it would come out of my budget.” Recently appointed CEO of Porsche, Matthias Muller, had earlier claimed that VW, which has a stake in Porsche, was planning a NASCAR bid.

Only 40 cars entered the NASCAR Nationwide Series race at Phoenix on 26 February – three short of a full grid and the smallest field in NASCAR’s second division since 2001. NASCAR attributed the slump to the long travel distance to Phoenix combined with the cost to teams of switching to the Nationwide Series’ new car.

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FIRESTONE OUT – THEN By Andrew Charman BACK IN – INDYCAR RACING BELOW Firestone has been an essential part of Indycar racing for many years. (Photo courtesy Indycar Media)

INDIANAPOLIS, IN: Tyre supplier Firestone quit Indycar racing and then reversed its decision in the space of a week.

On 4 March Firestone announced it was quitting US open-wheel racing at the end of the 2011 season, following the lead of its parent company Bridgestone which left F1 after the 2010 season.

Firestone has been in Indycar and its predecessors for 21 years and has been the sole tyre supplier since 2000, when Goodyear conceded defeat in a five-year battle with its rival.

The decision, which included dropping the title sponsorship of feeder series Indy Lights, was taken after extensive negotiations between IndyCar and Firestone failed to reach agreement, plunging the race series into a potential tyre supply crisis in the same year that it will introduce a raft of chassis and engine changes.

However, only a week later Firestone announced that it would after all be staying in the series for the 2012 and 2013 seasons.

“We are pleased that we were able to reach this agreement with IndyCar,” said

Firestone Racing executive director Al Speyer. “While we’ve reached the pinnacle of success in the IndyCar racing, we’re happy to extend our relationship with the IZOD IndyCar Series through 2013 and to continue our winning partnership.”

The turnaround is believed to have followed serious lobbying of both sides by IndyCar teams, who were desperate to maintain one constant factor in all the changes of 2012.

However, the deal only covers IndyCar– the Indy Lights series will need a new sponsor and new tyre supplier for the 2012 season. RT

Meeting an industry giant and business trips to the US STONELEIGH PARK, UK: The Motorsport Industry Association (MIA) is hosting an event at the Williams F1 conference centre in Grove, Oxfordshire to pay tribute to the legendary designer and engineer Dott Ing Gian Paolo Dallara, founder of Dallara Automobili, the world’s largest racecar company. The venue has been selected as he designed the F1 De Tomaso used by Frank Williams – the start of a lifelong friendship between these two motorsport giants.

The evening on Thursday, 7 April will begin at 18:00 with a business networking reception and tour. Dinner will begin at 19:30, with the

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Gian Paolo Dallara interview commencing at 21:00. The evening closes at 22:30.

The MIA is also organising three separate trips – San Diego/Santee, Charlotte/ Mooresville and Indianapolis/Brownsburg – all taking place on 20-25 May. The NASCAR business tour includes taking in the NASCAR All-Star Race at Charlotte Motor Speedway, the off-road tour to California that incorporates the Lucas Oil Regional Off-Road Series at Glen Helen Raceway near San Bernardino and the IndyCar and drag business tour that includes a visit to the Speedway for the

Indy 500 as part of the attraction.

These tours offer unrivalled access to US companies using the MIA's extensive network of US motorsport contacts before, and during, the business visits and shop tours, promotion of your company to targeted US companies, prior to your arrival, to encourage their active interes and a place at VIP business networking events at each centre where the real decision-makers and buyers can be met.

For further details on these tours and the Dallara event, contact charlotte.austin@the-mia.com RT

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SENSOR TECHNOLOGY HELPS BREAKS RECORDS TOWCESTER, UK: Variohm EuroSensor has added high-performance EGT and tuning temperature sensors to its motorsports sensor range in a UK, Ireland and European distribution agreement with the leading US thermal measurement specialist, Zip Sensors, Inc. The agreement brings a complete range of premium quality Type K sensors which have a rich pedigree of motorsports success and a strong reputation for high reliability and durability across a broad spectrum of applications for exhaust gas monitoring and other critical thermal measurement areas.

Zip Sensors’ leading position was recently demonstrated following its close support for the winner of the recent world land speed records for a standing mile which took place at the Texas Mile event held in Goliad, Texas during October 2010. Zip Sensors supplied specialist EGT sensors and cylinder head temperature sensors to the Wild Bros Racing Team and winning rider Bill Warner for its turbocharged, 1299cc Suzuki Hayabusa which reached a world record speed of 278.6 mph (448.36 km/h).

This competition for the World’s Fastest Streetbike followed similar successes with consistent track records in standing mile events across the US during 2010. With just a few attempts allowed and with meticulous detail required for the bike setup, the events consist of a standing start with a mile of track to reach terminal velocity and just a half mile to come to a controlled standstill. Such land speed record events are known for extreme environments with very high operational temperatures and excessive vibration for long periods of test and track use.

The 650 hp machine included four exhaust gas temperature sensors that were built to the Wild Bros Racing Team's specification with Type K calibration, exposed tip sensing junction, high temperature lead wire and type K miniature connectors. With all stainless steel construction and high-tech ceramic components used for insulation in the area

of the lead wire and thermocouple junction, the sensors featured brazed rather than crimped construction to ensure complete reliability in critical stress areas. Two sensors were customised with precisely modified bend radii to fit within the confined area around the turbocharger. The cylinder head sensors, also with type K calibration were hand formed for interfacing the end of the thermocouple to accommodate existing cylinder head bolts.

WIDE RANGE OF APPLICATIONS Such specialist customisation is fairly typical for Zip Sensors, but the high-performance sensor manufacturer also has a complete range of off-the-shelf Type K sensors for demanding temperature measurement applications across all areas of motorsports.

Several standard configurations are available that work well with all types of racing from drag racing to motorcycle to Formula One as well as diesel applications.

Standard versions help to shorten lead times for customers and makes the quotation process quick and straightforward. Aimed at users from the

serious enthusiast to professional race teams, the standard sensors include the entry level Sportsmen's Series with exposed tip sensing in stainless steel and Teflon insulated conductors to the Pro Series featuring grounded enclosed tip sensing in Inconel stainless steel with optional ceramic fibre insulation with stainless protective braid.

Essentially covering temperatures from 100ºC to + 1300ºC, the complete range includes EGT variants for diesel, petrol, methanol and nitro exhausts with Type K calibration and complete compatibility with data loggers. Thermal sensors specifically for use on motorcycles and dynamometers are also available.

“Variohm’s interest in expanding its line of temperature sensors and Zip Sensors specialisation in high-end, quality motorsports products will be a well matched alliance, ”said Thomas Krutulis, Zip Sensors CEO. “We are very excited to be entering into the innovative and winning focused UK motorsports market, and Variohm’s expertise and support will enable us the very best platform for success.” RT

RIGHT The 1299cc Suzuki Hayabusa that reached a world record speed of 278.6 mph

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COVER STORY ACCIDENT INVESTIGATION

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HE MURDER committed by Colonel Mustard in the study with the candlestick, and low ambient temperatures and the subsequent embrittlement of some critical ‘O’ rings causing the catastrophic failure of the space shuttle Challenger, have one thing in common. In both cases forensic science and engineering were used to determine the cause of particular, undesirable, outcomes.

Forensic engineering is the objective investigation of conditions related to material, equipment or construction failures and accidents, including those involving human factors or catastrophic events. It involves the technical evaluation of those conditions and the application of engineering principles to determine the cause of such failures and accidents.

In a motorsport sense we need to apply the same rigorous and disciplined investigative approach to determining the probable causes of an event, whether that event is an accident in the classic sense or merely a failure that has led to a race retirement or the loss of valuable testing or practice time. The consequence of the two types of problem may differ in magnitude but the investigative techniques that should be applied are similar.

BELOW Where should the blame lie when a driver stalls his car after a pit stop (demonstrated here by Giancarlo Fisichella)? The answer isn’t as straightforward as you might imagine (Photo: Etherington/LAT)

THEORIES OF INCIDENT CAUSATION There are several theories of accident or incident causation. It is very rare that a single cause leads to an accident or failure even if, at first glance, it may seem obvious that a particular shortcoming led to the

Forget TV’s ‘Crime Scene Investigation Vegas’, Pat Symonds explains how the real-life investigative procedures put in place in Formula One hold true, whatever your level of racing

ABOVE When the wheels have come off the wagon, how do you begin to establish what happened? One tip is to collect as much photographic evidence as possible. It was bountiful in the case of Hunter Abbott’s escape from this huge shunt at Oulton Park (Photos: Gibson/LAT)

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Accidents are rarely simple. What may appear to be blindingly obvious may have no bearing on the true cause� final outcome. For example, if we take something as simple as a driver triggering anti-stall leaving a pit stop and consequently losing race position. It is very easy in such circumstances for an engineer to absolve himself of blame and pass responsibility totally to the driver. Surely, it is not too difficult to coordinate throttle and clutch sufficiently accurately to be able to leave a pit stop with maximum performance? Well yes, one would think so.

But what if the clutch engagement is extremely sharp and the throttle mapping

the press applying this flawed thinking to a complex problem.

While it is uncommon for a catastrophic failure to be caused by a single, identifiable, cause, statistics are often presented which will lead to the belief that such causations are common. The main problem with accepting this view is that it leads to lazy and incomplete investigation of the true origins of the incident. The likelihood of a single causal circumstance should generally be discounted until the complete chain of events has been investigated rigorously.

SILVERSTONE! 3

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such that a positive torque slope is not always present with increased demand?

Unquestionably then the engineer must accept some, if not all, of the responsibility for a fluffed pit stop.

In this case there is not one single causation. If the control engineer had mapped the clutch better, if the person responsible for engine calibration had mapped the torque demand better or indeed if the driver had been more skilled, the stall would not have happened. The reality is that it took deficiencies in each of these areas to lead to the problem occurring.

This theory covers many, if not most, circumstances. It is often called the domino theory because it mimics the fall of a chain of dominoes initiated by an unstable domino at the start of the chain.

While somewhat trite, it is perfectly embodied in the old proverb that goes: For want of a nail, the shoe was lost.

For want of a shoe, the horse was lost.

For want of a horse, the rider was lost.

For want of a rider, the battle was lost.

For want of a battle, the kingdom was lost.

And all for the want of a horseshoe nail.

THE SINGLE EVENT THEORY While rare, there are accidents or failures that come about as the result of a single event. If something falls into this category then the investigative task is simple. As soon as the cause is found and corrected, the job is done. Unfortunately, ill-informed opinion will often seek this simplistic solution. The media are particularly adept at believing that this theory prevails. Recent tragic events in Japan regarding the failures of the protection systems in the nuclear power stations affected by the earthquake and subsequent tsunami are examples of

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THE CHAIN OF EVENTS THEORY

If this theory is to be applied, the investigator should seek information that could explain a sequence of events that led to the final catastrophe.

THE BRANCHED EVENTS CHAIN THEORY In some respects, this theory is similar to the chain of events theory except that rather than being a linear chain of events, it presupposes that an outcome can be achieved by movement along various branches of a treelike structure. The outcome, while still relying on a certain chain of events, can find

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COVER STORY ACCIDENT INVESTIGATION BELOW Jarno Trulli is helped out of his wrecked car after a heavy crash at the 2004 British Grand Prix. It was this incident which prompted Renault F1 to put in place rigorous investigation procedures (Photo: Etherington/LAT)

successive events along multiple branches of causation.

The method was developed for the analysis of missile safety. It presupposed that an accidental launch would eventually occur if there were any possibility of a pathway to inadvertent firing existing. The method is often portrayed as a “fault tree” with the final failure being depicted as a single event at the top of the tree with a pyramidal structure of events below it, any branch of which could lead to the top-level outcome. For this reason it is sometimes known as the “Fault Tree Theory”. The graphical nature of the logic in itself is a powerful tool for understanding the data that may need to be inspected to determine the causation of an event.

The likelihood of a single causal circumstance should generally be discounted until the complete chain of events has been investigated”

ABOVE Time is precious at race meetings and test sessions alike, but care must be taken to retrieve all the components from a crash site

OTHER THEORIES The three theories outlined above are not the only hypotheses but if an investigator starts with them in mind, they are likely to arrive at a sound conclusion in most cases. Among the many other theories, the determinant variable theory, for example, is one that is well suited to multiple incidents where statistically significant samples are available. Such theory may well determine that, on the road, a driver’s age is significant in his likelihood of being involved in an accident. While a powerful theory if the data is available, it is rarely of use in motorsport. It could however occasionally be used, for example, to lead to conclusions such as the propensity for high differential dog speeds during a gear insertion to result in physical damage of the gear dogs. For further information on such theories (and indeed investigative techniques), a useful reference is The Investigative Process Resource Research site. [1] THE IMPLICATIONS AND PITFALLS Each theory leads to pitfalls for the investigator. The single event theory is by far the most dangerous as it leads the investigator to cease investigation as soon as he has found what he believes to be the single cause. In so doing, he will undoubtedly close his mind to the sequence of events that needs to be tackled in order to prevent a reoccurrence. Accidents are rarely simple and sometimes what may appear at first sight to be blindingly obvious may have no bearing on the true cause. In order to reach a sound conclusion all facets of the case must be studied and, just as propounded by Sherlock Holmes, it is often the case that elimination of potential causes is as important in determining the origin of an outcome as establishing the ultimate reason directly.

Even the domino theory has limitations. The determination of the start and finish of the chain are subjective assessments of the investigator and, while the end is normally easily determined, the start is less clear-cut. Even the end of the chain should be considered.

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COVER STORY ACCIDENT INVESTIGATION

Is the outcome that physically occurred the only possible one or was there a likelihood that had a particular component stood up slightly longer, then the chain would have failed elsewhere resulting in a different, but still unwelcome, outcome? One advantage of such consideration is that the data search is likely to be disciplined by consideration of the component parts of the chain.

The branched events chain theory predicates that the investigator will focus on identifying the critical path to failure. Again, the start, and even the end, of the branched phenomena are subjective. The logic of determining the tree however tends to focus data collection in relevant areas. It may even throw up speculative areas that may not have been considered if other, more simplistic, approaches were employed.

The principal conclusion of these methodologies is that an accident is not (generally) a single event but a process in which a normal activity is transformed into an unacceptable conclusion involving certain

necessary or sufficient conditions interacting.

The object of the investigation is to isolate these conditions and describe the entire process that caused these conditions to become catastrophic.

THE PERILS OF DATA While it is obvious that a lack of available data will seriously hamper an investigation, incorrect or misinterpreted data is in some ways more insidious in that it can lead to false conclusions being drawn and defended.

Any data analyst must be fully aware of the dangers of quantisation, aliasing and filter time constants but never more so than when investigating an accident when the particular sequence that events occur in is of prime importance. This is particularly true of accident investigation. When events occur in rapid succession, an array of sensors with differing frequency response or filtering can, in the extreme, lead to incorrect conclusions as to the sequence of those events.

DETAILED METHODOLOGY Accident or failure investigation is a oneshot affair. If clumsy handling were to destroy a piece of evidence, that evidence will be lost forever and the true cause of the problem may be either not determined or incorrectly determined.

The methodology will vary slightly depending on whether a catastrophic accident has occurred (which may of course have far reaching legal implications) or if the incident has led to a race retirement or time loss in testing. While responsibility for the accurate conduct of the investigation lies with every team member, it is vital that a senior engineer is put in charge of the enquiry immediately. It should be remembered that the purpose of the investigation is solely to prevent a reoccurrence, not to apportion blame.

Making this clear at the outset should ensure the correct spirit of cooperation from all concerned. A prime objective is to ensure

ABOVE One of the toughest calls for teams is whether to carry on with the race if the cause of a failure can’t be traced. The 2005 US GP descended into farce after Michelin was unable to replicate and understand the tyre failure that had caused Ralf Schumacher to crash in qualifying. Its teams therefore had no choice but to retire to the pit lane as just six Bridgestone runners made their way to the start (Photo: Coates/LAT)

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that evidence is forensically preserved and not inadvertently destroyed by a wellmeaning investigative assistant!

In a two-car team, the immediate decision to be made in the event of a serious failure is to determine the likelihood of a similar occurrence on the other car. This is a difficult decision to make but, during testing, one should always err on the side of caution and, if running two cars, the other should be stopped until the incident is understood.

Remember that the decision does not just affect the safety of the driver but possibly that of spectators and track workers.

The senior engineer tasked with heading

previous laps and if relevant, the other car.

The study of the data is not just useful in determining the chain of events in the incident but is also useful when trying to reproduce failures on test rigs later on.

2005 USA GRAND PRIX A famous and unfortunate example of this occurred in 2005 when there were tyre failures during practice for the USA Grand Prix at Indianapolis. After practice, Michelin, whose tyres were affected, collected data from all of the teams concerning the loads, speeds and dynamic camber angles of the relevant tyres. Using

ABOVE The same investigative approach can be applied to the loss of valuable track time in testing, as well as to serious accidents. Here Rubens Barrichello checks the rear of his Williams (Photo: Dunbar/LAT) the team must have absolute authority and that ultimate influence should even extend beyond his normal remit. For example, if he is a chassis engineer he should have full authority over engine engineers. His word must be final until all trackside investigations are completed and all evidence is gathered. At that point he may, if it aids the investigation, hand authority to a factory-based engineer who will normally be a senior designer.

The engineer in charge of the investigation should assign tasks to others. These should include tasking the performance engineer or data engineer with reviewing the data both pre-accident and during the accident. In doing this he should make comparisons of

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this data they worked through the night at facilities both in France and in North Carolina to reproduce the failures and make recommendations as to the safe use of the tyres. Unfortunately, in this case, a foolproof solution could not be found and rather than risk a catastrophic event at the race, the Michelin teams had to withdraw.

While the outcome was unfortunate, the decision process was rigorous, having been made so by the availability and application of the recorded data.

With data analysis in place, the team manager should try to obtain recordings of any video evidence from broadcast media or circuit CCTV systems as well as getting any photographic evidence from anyone at

the site of the accident. If the accident is sufficiently serious that it may have legal implications, then he should establish the contact details of any witnesses who may be able to help further investigation (this includes marshals, paramedics etc). When Jarno Trulli had a very big accident on the exit of Bridge Corner during the 2004 British Grand Prix at Silverstone, the circuit CCTV cameras proved to be of significant help as we tried to understand the sequence of events leading up to impact. In fact it was that very incident that led me to study and formalise the whole process of accident investigation.

The engineer in charge should visit the site of the accident as soon as possible and take photographs and notes of any evidence that may exist. A thorough search should be made for components that may have come off the car and their position noted. Remember that someone may have already moved parts. Also, note any marks, gouges or fluid spills that are present on the track. There will not be unlimited time available at the accident site, so ensure that everything is photographed from every angle.

A sketch should also be made with annotation of the location of the various pieces of evidence. This can be used subsequently to mark up the photographs. It will only be much later that the value of this is appreciated as questions are asked of where various components ended up. After a disc brake failure in testing at Monza in 2006, we were only able to determine the mechanism of failure once we had found a specific part of the disc drive components that was buried in the gravel trap at the Ascari chicane. Inspection of this part yielded the evidence we needed to prove what was until then just a theory.

The driver is a valuable witness! Make sure he gives his view of what happened and that this is written down as he says it. If the car is carrying an Accident Data Recorder, make sure this is downloaded as well as any

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conventional data acquisition system.

Back at the garage, a quarantine area should be set up around the car and all components involved n the accident should be returned there. It should be supervised, generally by the chief mechanic, and treated as a no-go area for anyone without specific reason and permission to be there.

The parts in the quarantine area should be subject to a careful visual examination.

Initially this should be done with minimum handling and, as at the accident site, should include numerous photographs. Handling components can lead to a loss of initial information and so must be carefully considered. Any loose parts should be labelled as to where they were found.

While everyone will be very willing to advance theories as to the cause of the incident, one should beware of venturing beyond the scope of one’s technical knowledge or indeed that of those who are offering opinions. If in doubt, concentrate on reporting accurately to those experts who will later assist the investigation. All parts that are to be returned to the team’s technical facility for further inspection should be listed and it should be made clear that they remain in quarantine, even on arrival back at base, until the investigating engineer releases them. Before leaving the circuit the car and the list of quarantined parts should be checked to ensure no significant parts are missing; if they are, a further inspection of the accident site should take place.

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In the short term, the engineer in charge at the track should collate all the information and actions above. He should also start summarising the findings in written form. If this is done in near real-time any inconsistencies or omissions will become evident before it is too late to rectify them. While tentative conclusions may be drawn, the engineer should be wary of drawing too rapid a conclusion, particularly if the perception is that there is a single causal circumstance. This is rarely the case and early public statements are often regretted later!

SCIENTIFIC MANNER Once the engineer in charge at the circuit is satisfied he has collated all possible evidence and done so in a scientific manner, he should pass responsibility to the chief designer who should appoint an individual with the relevant knowledge to advance the investigation. It should also be his duty to apply the principles of investigation to look for the underlying causes of the incident.

A formal report should ultimately be issued detailing the causes of the accident and the circumstances leading up to it.

The purpose of the report should be to identify changes to design or procedures

that need to be made to prevent a reoccurrence and to improve methodologies such that similar incidents are avoided in the future. All contributing factors need to be analysed and thought applied as to whether they may, in different circumstances, lead to additional problems of a similar or disparate nature.

To summarise, there are four key steps in the principles of investigation, irrespective of the accident theory employed.

The first of these is to acquire data and to acquire it using methods that would withstand forensic scrutiny. This data may be recorded electronic data, photographs, damaged components or witness statements and should also include the absence of data which may, in itself, yield conclusions just as surely as if it were physical data.

Secondly, the data should be organised and formalised. It should be catalogued in a form that others can follow. It is no good sending a file from the data acquisition system to a designer who is not familiar with using the data analysis software. It is

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ABOVE A mountain of data has become part and parcel of professional racing.

While lack of information can clearly hamper an investigation, so can incorrect or misinterpreted data (Photo: Tee/LAT)

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far better, initially, to capture the graphical data as an image and annotate it so it is easily understood. A simple export of ASCII data may be more useful for the early analysis. At a later stage, the designer can interrogate the data with help from a specialist. Be conscious of the quality of the data and ensure that nonspecialists are aware of any limitations such as inconsistent zeros, quantisation or the time constants associated with different filter poles.

Thirdly, all the data should be integrated in such a way that it is possible to create a description of the likely sequence of events. This should assist in deciding on the relevance of the collected data although at this stage nothing should be discarded.

Even if conclusions are starting to be drawn at this stage, they should be regarded as tentative. They certainly should not influence any description of events.

Finally, the description and any tentative conclusions should be validated. A conclusion can only be regarded as validated when it becomes impossible to disagree with that conclusion in a reasonable manner. To provide validation any supporting evidence

The purpose of the investigation is solely to prevent a reoccurrence, not to apportion blame”

ABOVE Peugeot looked set to romp to victory at Le Mans last season until three of its 908s retired with engine failure. Its rigorous investigation revealed that conrods were responsible for all three failures, albeit on different cylinders. The components had been tested exhaustively in the build-up to the race, but a track surface featuring a higher than expected level of grip meant that the cars spent longer than anticipated at full throttle

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must be collated and critically appraised. If a conclusion is difficult to form, try to imagine what criticism others may have of the description of events. Try to make the description as comprehensive as possible such that someone reading it could mentally visualise the scene and the sequence of events that led to the incident.

Ensure the description is clear, concise and complete.

While the methodology outlined above is, in general, written presupposing that a physical accident is being considered, many parts of it are equally applicable to situations where an unexpected failure has occurred. A race retirement due to a water leak, for example, may be nowhere near as dramatic as one caused by impact with the Armco but the effect on the championship is just as severe.

In order to approach a “zero defects” philosophy, rigid discipline must be applied to all faults. By considering a forensic approach to any investigation, the likelihood of reaching a true conclusion is increased. Equally, only a truly methodical approach can highlight deficiencies in procedures and operations that may one day lead to problems. A well-conducted investigation will therefore, not just throw light on the current predicament but is also likely to avoid similar problems in the future. RT

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GASOLINE’S LAST STAND Chris Pickering reports on the AMR-One, the car Aston Martin has designed with the aim of ending diesel dominance at the Le Mans 24 Hours

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HE BUSINESS of keeping secrets is a serious one. Even by the standards of ‘the industry’ the gathering was low key; a discreet get-together, shrouded from prying eyes and safely away from inquisitive ears. It was here that 007 was to slip quietly out of the shadows. Except this time it wasn’t Ian Fleming’s secret agent that bore the eponymous serial number, but the flanks of Aston Martin’s new Le Mans prototype. It was the first example – or perhaps the first publically shown mock up – of the new AMR-One, which will take to the track at Le

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Mans in barely more than two months’ time. And yet much of the design remains a secret worthy of the car’s literary namesake.

It’s a brave step from the plucky British firm. For three years now it’s put up a far better fight against the all-conquering diesels of Audi and Peugeot than an outfit of its size had any right to expect. But the Lola-derived B09/60 coupes were one thing; designing and building your own car from scratch is quite another, and Aston Martin has gone in at the deep end.

The new car is a change of philosophy that

sees the large capacity V12 (now outlawed in the LMP rules) swapped for a petite twolitre six-cylinder turbo. At the same time, the coupe design is being dropped in favour of an open layout, just as Audi, which had so long resisted the concept of a fixed head, shifts in the other direction.

There’s talk of a radical new concept for the aerodynamics too. “We believe our solution is quite novel,” comments Aston Martin Racing’s technical director George Howard-Chappell. “You’ll see the approach we’ve taken emerge as we get some running, our aero choices have been pretty aggressive. It’s not a single-seater with mudguards, it’s a full sports car designed from scratch for that purpose.”

It’s an intriguing statement. And yet for all that’s apparently new and exciting at

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ABOVE The AMR-One represents the first time Prodrive’s Banbury-based engineers have designed a race chassis and engine not based on a production car

Aston Martin Racing, the company is remaining remarkably tight-lipped about the details. Granted, we’d find it a bit strange if they were circulating blueprints around the paddock and inviting Audi over

no obvious signs of game-changing aerodynamic devices. In fact the whole design is remarkably neat and free from appendages in general. It bears all the hallmarks of a car that’s been designed solely in CFD (as indeed it has by simulation specialist TotalSim). It’s possible that the car will sprout the odd dive plane or Gurney flap before the big race, but the regulations prohibit very much else being added externally.

The high waistline of the Aston gives the impression of bulk, but actually, at 2930 mm wheelbase, it slots neatly between that of the Audi and the Peugeot. The large

The AMR-One’s air management differs to that of the other cars” for tea, but the cloak of secrecy surrounding the AMR-One has been particularly strong, even in the context of professional motorsport. So what exactly is this novel new solution that Aston Martin’s very own Q-branch has devised?

From the outside it’s not immediately apparent. There are no grand gestures and

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plan-view area this gives helps to boost the effectiveness of the underfloor tunnels, as is the trend with other designs. Meanwhile the chunky feel at the front suggests designers have capitalised on rules that make it easier to achieve a higher footbox design on open cars than on coupes. This is then extended forwards by the bodywork into the familiar high-nose design.

Underneath the nose there sits a boatshaped bow, flanked by two carbon fibre supports. As well as their structural function, linking the nose to the splitter below, these act to split the airstream and direct it around either side of the monocoque.

Although this is more prominent on the Aston, it’s another well-established principle that’s seen on plenty of other designs, including the current Peugeot 908.

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wishbones that form the front ducts are there largely to ensure the car conforms to the sports car regulations, but they also allow air to pass over the front diffuser and merge with that flowing underneath. This air is then directed around the sides of the chassis as it would be on a single-seater before finding its way to the proper ducts for the cooling systems, which are most likely hidden just behind the wheel pods. In the Aston, however, it’s more difficult to say what’s happening. The air coming out of the front diffuser may be directed past the heat exchangers or it may be channelled more or less straight out of the louvers on the side.

If there really is something radical at work it would have to be very clever” Following the air back we reach the two main ducts that sit either side of the nose. There's nothing unusual about these – that's the way the Peugeot originated – but what is slightly unconventional, however, is a pair of additional nostrils set higher up and further back. The two main ducts sit in an area of high-energy air, which means there isn’t usually a problem generating adequate cooling flow. The presence of the additional ducts may point to disrupted flow entering the main ducts, caused by a particularly extreme diffuser design. There’s also a somewhat more leftfield theory to explain their presence, but we’ll come to that later.

Despite the apparent similarities on the basic front end layout, there’s no doubt that the AMR-One’s air management differs to that of the other cars. On the 908, for example, the panels above the BELOW The AMR-One is an elegantly simple design, with the box sections at the side reminiscent of Audi’s R8 and R10 designs

BOX SECTIONS Above, the sides of the bodywork sweep up to clear the front wheels before running almost level to the rear wheel arches.

This effectively forms a pair of box sections along the sides, almost square-sided and not unlike those seen on the original open-top Audi R8s and R10s. A set of louvers vents the potential pressure build up in the wheel arches and a larger set mark out the cooling exit on the sides, but apart from that it’s an elegantly simple design.

The slab-sided approach has almost certainly been adopted in an attempt to keep the airflow attached.

As it crests the top of the wheel arch and starts to head downwards the natural tendency is for the flow to separate. You get a similar effect in the horizontal plane too if you're running an individual wheel pod that narrows down to a trailing edge. In each case the air is likely to fall off the edge and becomes turbulent. It seems Aston Martin has turned to this

BELOW Note the vents, stacked vertically, at the base of the FIA-mandated longitudinal fin

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Congratulations & Thank You

One, Two overall winners:Chip Ganassi Racing / BMW Riley

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approach to prevent separation, just as Audi did in the past. It’s a well-proven technique, but it’s not without its drawbacks.

The squared-off sidepod approach manages the flow effectively as it moves backwards along the car, but it remains basically a 2D solution. The philosophy that Peugeot used to great effect with the original 908, which can now be seen on the new car along with the Audi R18, works in three dimensions, drawing air over the more complex, rounded sidepod geometry and sending it spilling onto the rear deck. This creates a high pressure area over the rear section of the car, generating downforce for relatively little drag penalty.

It’s hard to say why Aston hasn’t done this.

It may not suit the flow over the rest of the car or it’s possible the aerodynamicists simply had a better idea that we’ve yet to cotton on to, but outwardly the sidepod geometry almost appears a generation adrift from the other cars.

Down the centre section of the car the big decision is clearly whether or not to go for a closed cockpit design. "We did the

modelling and decided that advantages like better visibility and quicker driver changes outweighed the small aerodynamic efficiency advantage a coupe could bring – which in itself has to be balanced against a higher centre of gravity," Howard-Chappell explains. But could there be other factors at work too?

COUPE DEBATE Clearly, adding a substantial structure above the driver’s head does raise the unladen centre of gravity. However, the footbox rules effectively allow you to seat the driver lower in a coupe, which is often thought to negate the centre of gravity penalty once the car is actually going round the track. Similarly, since the changes to the pit stop regulations in 2009, which effectively make wheel changes the most time-consuming part of a stop, the pressure has been taken off driver changes to the point where the added complexity of threading someone in or out of a coupe is no longer considered to be an issue. This means an increasing number of

constructors are turning to the aerodynamic efficiency advantage offered by a coupe.

Most significant among the converts is, of course, Audi. The company’s previous attempt at a closed top LMP, the R8C of 1999, was an ill-fated affair, dogged by handling issues and a fundamental lack of pace. It’s no secret that the experience left Audi Sport team boss Dr Wolfgang Ullrich very wary of coupes, and he remained a strong advocate of the open-topped designs, even once the pit stop regulations had denied them of their main advantage.

Yet, with the reduced power offered by this year’s engine regulations, even he has been forced to reconsider.

“The rules mean you have to have a roof to be competitive,” Ullrich explains.

“Driver changes are always easier with open cars, but the rule changes have taken that away [and] the smaller capacity engines make aerodynamic efficiency more important. It breaks my heart because I love the open cars.”

So, with even the staunchest supporters of open cars now defecting to the coupe

BELOW The AMR-One is said to boast a “novel” aero approach but details have been shrouded in secrecy as teams bid to disguise their approach to the new rules

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camp, why run an open car? It’s likely the real reasons are rather more down to earth.

Building a coupe is fundamentally harder than an open car. Any serious Le Mans prototype is going to be a massive undertaking for a team that’s never designed or manufactured one from scratch before; something as simple as demisting a screen or getting the air conditioning system to function properly can turn into an unexpected nightmare, even with the budget and manpower the

ABOVE The AMR-One will go direct from CFD to the racetrack, a route Aston Martin originally pioneered with its DBR9 sports car

major OEMs can bring to the table. The likelihood, then, is that the decision was entirely pragmatic. It makes perfect sense for a relatively small team embarking on its first in-house project to start with an open car, and you can’t help wondering if that’s the true heart of the matter.

Behind the cockpit bulkhead the packaging requirements are, of course, dominated by the engine. While a sixcylinder design will always be longer than an inline four, Aston insists that the LMP’s

wheelbase meant this wasn’t an issue. And what we can see certainly seems to support this. The engine cover comes down in a smooth sweep from the regulation height of the cockpit to the rear deck. It doesn’t appear to extend much further back than the rival designs, although notably it doesn’t seem to achieve any reduction in area over the wider vee-engines either.

As it reaches the tail, a single strut, incorporated into the ACO-mandated longitudinal fin, holds the rear wing. At its base there is a pair of rather curious vents, stacked vertically on top of each other. Their positioning is too low to dramatically alter the flow over the rear wing itself, so it seems unlikely they’re an F-duct style drag reduction device. They do still feed into the wake of the wing, however, so it's possible, if there's enough energy there, that this flow could be used to connect the flow over the wing with that coming from the rear flip. But if it's just coming out the engine bay there wouldn't be enough energy there to make a useful contribution, because the tortuous route around the sidepods would de-energise the air. And it’s here that the mysterious nostril ducts mounted behind the nose may come back into the story. It’s just possible that these are feeding highenergy air straight back to the outlets in the rear to fill the wake.

AGGRESSIVE AERO

ABOVE Aston Martin Racing has punched above its weight at Le Mans with the Lola B09/60 coupe (Photo: Bloxham/LAT)

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But what if that rather tenuous assumption is wrong? In that case there really is no outward sign of the novel and aggressive aerodynamic philosophy that Aston Martin claims to be adopting. That would leave any truly unusual solutions on the current car underneath the bodywork, but that too seems unlikely. To channel air in and out for complex internal aerodynamics requires a lot of holes, and the relatively clean design of the Aston doesn't suggest that's happening. If there

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NEW CARS ASTON MARTIN AMR-ONE BELOW Having stubbornly resisted switching to a coupe, Audi now has some catching up to do with its R18, seen here testing at Sebring with the open-top R15 it succeeds (Photo: Audi Motorsport) really is something radical at work it would have to be very clever.

The engine choice is also somewhat unusual. In the past plenty of manufacturers have elected to go with inline fours (historically in LMP2, and now in LMP1), but it’s been the best part of three decades since a straight six graced the prototype grid at Le Mans.

“We have chosen to run with a sixcylinder turbocharged engine because we believe this offers the best potential within the petrol engine regulations,” states Howard-Chappell. But why exactly? The exact source of the powerplant has – naturally – been kept secret, and there’s no real explanation for the decision to go with an inline six.

SIX APPEAL Conventional logic holds that a straight six has an inherent advantage in balance compared to most configurations, but that can be misleading. In theory it’s a near-perfect layout. The six cylinders are effectively arranged as two sets of three, which mirror each other, so that pistons one and six are always in the same position inside the bore; as are two and five, and so on.

Because the cylinders move in mirrored pairs there is theoretically no difference between the two halves of the engine.

Similarly, the 120-degree crankshaft angle means that the difference in piston acceleration at various points is also cancelled out across the six cylinders. But the problem is that both of these statements assume a completely rigid crankshaft. In reality the slightest deflection can alter the phasing between the cylinders and set up a torsional oscillation along the crankshaft, which can become a real problem.

You can, to a certain extent, overcome this by altering the firing order and introducing damping to the crankshaft, but it’s by no means trivial. Likewise, the reduced piston weight that six small cylinders offer over, say, four slightly larger ones is unlikely to be a major advantage in a relatively lowrevving turbocharged design. With this in mind, it’s possible that Aston Martin has other reasons for adopting a six.

The answer may lie with the road car side of the business. Aston Martin CEO Dr Ulrich Bez is known to be “extremely interested” in a return to straight six engines for the

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BELOW Advantage Peugeot? Of the three main protagonists, the ‘all-new’ 908 is the closest in concept to its predecessor. But Sebring demonstrated that upsets do happen (Photo: DPPI/Peugeot)

company’s production output. The use of smaller, turbocharged inline sixes, equipped with direct injection, would help to address forthcoming emissions requirements, while still neatly dropping into the space left by the current V12s. And although the racing engine clearly isn’t subject to the same requirements, it’s possible that Aston Martin may be pre-empting some sort of link with the new road car technology, whether in engineering terms or marketing.

You could, equally cynically, suggest that the six-cylinder engine offers a quick fix to a team that’s just been forced to downsize away from a V12. Although there’s clearly more to creating a straight six than just lopping off one bank of cylinders from a V12 it is possible that elements of the design could be carried over. This would help to reduce the time and cost of producing the engine, which would be a logical decision

for a team on a budget (if not, perhaps, a particularly sexy one to include in the marketing material).

So will the diesel dominance continue?

The ACO has made renewed pledges to ensure a fair playing field between petrol and diesel entrants this year and it’s possible that the performance gap will shrink somewhat as a result, but that may not be the real issue.

BALANCE OF POWER “Personally I don’t think it’s a matter of petrol versus diesel,” comments Peugeot Sport director Olivier Quesnel. “I think it’s a case of factory cars against a private team. I think Aston Martin should be competitive, but if Peugeot or Audi had a petrol engine I think we could be at least as competitive as a diesel car.”

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ABOVE The neat and free lines of the AMR-One testify to its development with Computational Fluid Dynamics

I don’t think it’s a matter of petrol versus diesel; it’s a case of factory cars against a private team” Both Audi and Peugeot are old hands at LMP racing now, so you’d expect the teams to be quite evenly matched. Likewise, with both running coupes this year, the aerodynamics and chassis engineering should be close. If anything Peugeot may have a slight advantage, because while we’re constantly reminded that the 2011 model is an all-new car it’s still the closest in concept to its predecessor. Having campaigned the old 908 since 2007, the team arguably knows more than anyone else about running an LMP1 coupe at Le Mans.

The Audi, on the other hand, is a more

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radical switch. By resisting the move to a coupe until the new engine regulations came in, it means the Ingolstadt firm has to manage two new concepts this year rather than one. That said, the addition of a roof can be deceptive – much of the lower body aero design is actually quite similar to last year’s R15 Plus and both diesel runners are thought to have been working on their 2011 cars for some time.

In the end the diesel battle is likely to come down to whichever team has better exploited the new engine regulations: the Audi with its V6 or the Peugeot with the V8.

So where does that leave the Aston? The British manufacturer has consistently placed towards the top of the petrol runners and there’s no reason to suspect that won’t continue. It’s also possible that it may be focusing on the ‘long game’ – fielding a basic iteration of the car this year to swing the performance balancing in its favour before following up with a more aggressive evolution in 2012 or 2013.

As things stand currently, however, there’s nothing to suggest it’s about to upstage the diesels. There isn’t any concrete evidence of this radical – so far undisclosed – aerodynamic direction, and some of the comments about it seem almost defensive, as if they seek to address accusations that haven’t even been levelled yet. Maybe deep down, even Aston Martin is preempting the continued dominance of those ‘single-seaters with mudguards’? RT

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NEW CARS MINI JOHN COOPER WORKS WRC

THE PERFECT RALLY CAR?

The MINI John Cooper Works WRC is presented to the public later this month. Chris Pickering visits Prodrive to find that while the name is familiar to rally fans, the selection process behind this project has broken new ground

A

S RALLYING icons go, they don’t come much bigger – perhaps ironically – than the Mini. In the hands of legends like Paddy Hopkirk and Rauno Aaltonen, the tiny front-wheel-drive machine swept all before it. It picked up the Monte Carlo Rally no less than three times, beating heavy hitters like the Porsche 911S and Austin Healey 3000 in 1964, 1965 and 1967 (some would argue that the Mini picked up a fourth win in 1966 before the organisers leveraged a technicality in the rules to hand it to the

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‘home team’ of Citroën…). In the process it became part of rallying folklore, but in 1968 the works team withdrew leaving the Mini’s brief but spectacular career consigned to the history books. Until now.

If any competition car was ripe for a revival it was surely the rally Mini. It may have gained a couple of pounds (and a few capital letters) in its current BMW-owned incarnation, but the idea of a 21st century MINI screaming up the Col de Turini in the original car’s red and white livery has to be a marketing man’s dream. The current model is

eminently suitable for the role, slotting neatly into the size constraints set by the new Super 2000-based World Rally Championship rules and even offering a four-wheel-drive variant in the production line up. And yet the story of how it came about is actually more intriguing than you might imagine.

It begins not in Abingdon, or even in Munich, but at Prodrive’s Banbury HQ in December 2008. At that time the company was still campaigning the blue Subaru Imprezas with which it had become synonymous, but all that was about to change with a call from Japan.

Subaru decided to withdraw from rallying, and at a stroke the Impreza rally programme stopped dead. This left Prodrive with a team of engineers without a project, but over the Christmas break Prodrive chairman David Richards came up with a plan. He decided to keep a core group of the engineers on to look ahead to what was then the forthcoming set of Super 2000-based

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RIGHT Initial development cars ran offthe-shelf rear wing profiles but the final car harnesses Prodrive’s cumulative aero data from years of rallying experience to give a wide operating envelope

LEFT Prodrive’s quest for the ideal rally car led to the development of the MINI John Cooper Works WRC, tested here by Kris Meeke (All photos: Prodrive)

The eureka moment for us was when we measured the suspension travel”

regulations (introduced this year).

Without a manufacturer to work with, the team – led by head of rally engineering Paul Eastman – was tasked with creating an ‘ideal’ World Rally Car concept without the constraints of any one chassis. “It’s a very unusual way of approaching the project,” he comments. “It’s certainly not something we’ve done before and I wouldn’t imagine anyone else has either.”

car, does it always continue to improve the performance?’ And, if not, at what point does applying additional resources fail to yield any improvement?” comments Eastman.

From this process the engineers divided the design parameters into two lists: primary factors, which are always worth developing; and hygiene factors, which only need to reach a certain point, beyond which they can be declared adequate. “The example we tend to use is the intercom,” says Eastman.

“Once you reach the stage where the crew can hear each other satisfactorily, there’s no point in continuing to channel resources into it. We knew how much budget we had and what resources were open to us, and it enabled us to decide what was important and what wasn’t.”

In the end a list of primary requirements

was drawn up, covering factors like suspension travel, weight distribution and centre of gravity height, and the group noticed that these were effectively determined by an even smaller number of key parameters. The process continued, and in the end it was decided the suitability of a production car for rallying could be defined by just four or five key factors. And these aren’t complex intangible concepts, but down-to-earth dimensions like mass, wheelbase and crankshaft centre line height.

The next step was to begin building a generic car model in CAD. Using the results of their initial study the engineers were able to define optimum roll cage layout, driver location and the running gear position within the boundaries of the Super 2000 rules and the typical B-sector cars they targeted. It

BELOW The strength of the chassis (this is the first ‘mule’ being pored over) enabled designers to add minimal material high up on the shell, thus negating its relatively high centre of gravity

RALLY CAR RATING PROCESS For Eastman and his colleagues the process began by poring over Prodrive’s accumulated data on its projects from the past couple of decades in an attempt to work out what made the ideal rally car. It was a highly scientific process, with a rating scale devised to statistically quantify the level of benefit that improving each factor of the design could bring. “The question was basically, ‘If we keep developing a particular part of the

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NEW CARS MINI JOHN COOPER WORKS WRC

enabled them to begin looking at fundamental attributes, like drivetrain efficiency, unsprung mass and even underfloor aerodynamics, months before they had a specific ‘donor’ car to work with.

One of the first things to come under

Prodrive to design more or less the complete roll cage before the base vehicle was known. Safety was paramount, and part of the philosophy the company adopted was to place the crew as far away from the point of a potential impact as possible. In

If you rip off the front bumper that’s 100 N of downforce you’ve lost for the rest of the stage” scrutiny was the suspension design. “We indentified the dampers as another major performance parameter in the development phase, so – much like the car as a whole – we started with a clean sheet of paper and tried to work out what makes a good WRC damper,” Eastman explains. “We took an old recce car and turned it into a testbed, honing our requirements. We’d had trouble in the past where we’d accepted a product from a supplier and then had to make it work on our car, but because we were in full partnership with Ohlins we could go out and work out our ideal spec and get the damper manufactured to that.”

The ‘generic’ rally car model also allowed

order to achieve this, they planned to use a very narrow transmission tunnel to move the occupants further inboard, and then bend the door bars of the roll cage further outwards to make best possible use of the space. “It sounds obvious, perhaps, but the more freedom you have in your starting point, the greater the opportunity to engineer these things,” comments Eastman.

“If we’d started off with a manufacturer from day one then I’m absolutely sure we’d have ended up with a very conventional cage, but instead we were free to construct the roll cage and then work out how we’d integrate it into the shell later.”

This unusual approach gave Prodrive a

valuable head start, but it couldn’t last forever, so Eastman and his colleagues started looking around for possible base vehicles. Some were ruled out immediately because their manufacturers were known to have in-house competition departments or close tie-ups with existing motorsport companies. Some were ruled out on budget grounds; it had been a tough year for the car industry, and a substantial investment in motorsport simply wasn’t on the cards for many manufacturers. A few – notably the base model R56 MINI – were too short to suit the new regulations, while, conversely, some, like the MINI Clubman station wagon, weren’t deemed wide enough.

DONOR SHORTLIST Before long, however, the team had narrowed it down to a shortlist of around half a dozen contenders and they set about sourcing a road-going example of each. From there, they took a series of measurements which enabled them to stretch or manipulate the CAD model to create a bespoke variant in

LEFT The elegant simplified engineering of the MINI WRC, such as interchangeable uprights and anti-roll bars, is a hallmark of Prodrive’s rally expertise BELOW Dampers were identified as a major performance parameter in the development phase

ABOVE & BELOW By the time Prodrive had access to the Countryman’s CAD data, virtually every aspect of the original rollcage design already fitted

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BELOW BMW’s motorsport division supplied a mildly modified version of the production-based direct injection four cylinder engine that was due to be used in its World Touring Car programme

ABOVE Measurement taking place on the first ‘mule’ chassis. The amount of work required on the bodyshell is half that of a previous generation WRC car

38

a matter of hours. It was a masterstroke that enabled the company to approach each manufacturer with a pre-prepared model of

manufacturing partner, Magna, in Austria.”

There Eastman, along with Prodrive’s technical director David Lapworth, was

‘its’ rally car – the CAD department even ghosted an outline of the appropriate car onto each model before meeting. And it wasn’t long before one candidate in particular began to stand out.

“In around May 2009 we heard that MINI was working on a new car that would be bigger than the R56,” recalls Eastman. “We didn’t know any details, but it looked promising based on the artists’ impressions in the media, so we approached MINI and then one day we got a call asking us to its

ushered into the firm’s prototype workshop where there sat a couple of Countryman prototypes. “Instantly we could tell they were likely to be suitable,” comments Eastman.

After taking a few measurements it became clear the Countryman had everything the basic MINI lacked: more suspension travel, bigger wheel arches and greater width. “The eureka moment for us was when we measured the suspension travel,” he says. “A lot of the travel is dictated by the top mount position and the wheel house provided by

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April 2011

the production design and, being a crossover design, the Countryman was perfect in those respects… ‘That is the car,’ David and I said to each other.”

AND THE WINNER IS...

That night they phoned back to the office with the measurements and Paul Doe, the CAD master, plugged them into the model. “By the time we got back he already had a feel for the sort of suspension travel and so on we could engineer into it, and by the end of the same week we had a very good idea that the Countryman was the car to focus on,” Eastman explains.

When the team had looked at the MINI Clubman in the past it became clear that the minimal frontal overhang would have made it difficult to package the cooling system.

The larger Countryman allowed for much greater freedom, but it was still a compact package overall. The only real downside, Eastman comments, was the roofline: “Despite the fact it’s a crossover, the frontal area is actually very similar to the other cars we were looking at, but the one problem you do have with the basic shell is its centre of gravity. We’ve used the shell’s natural strength to our advantage here, though, ABOVE The MINI WRC has a lot to live up to. This is the Mini and avoided adding too much Cooper S of Paddy Hopkirk and Henry Liddon speeding along extra material high up, which the Monte Carlo harbour front en route to victory in the 1964 Monte, the jewel in rallying’s crown (Photo: LAT) we believe has pretty much

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BELOW The full-scale drawing of the wiring harness for the first MINI test car, on which the harness is laid up and built

The suitability of a production car for rallying is defined by key factors like mass, wheelbase and crankshaft centre line height”

negated the problem.”

In December 2009 Prodrive reached a formal agreement with BMW and the team gained access to the Countryman’s CAD data. Fortunately, virtually every aspect of the original cage design already fitted, and they were able to draw other advantages from the base car’s design too. After measuring the production shell’s stiffness they were able to reduce the amount of tubing in the roll cage, for example, which once again comes down to the philosophy of engineering to a carefully determined requirement.

“We could have spent many more months developing ever stiffer roll cages, but there comes a stage where it doesn’t actually need to be any stiffer,” Eastman comments.

Similarly, he recalls, because the basic shell is so stiff the engineers found they could actually mount directly to it: “In the old days the original body was virtually ignored in the structural design, but due to the new regulations and the strength of the Countryman shell we’re able to do more with the road car’s structure – the engine mounts, for example, are mounted directly to the monocoque with no reinforcement.” Overall, this means the amount of work required on the bodyshell – and hence the cost – is around half that of a previous generation WRC car; something which is sure to appeal in these cost-conscious times.

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While the car was quietly developing, so too were the rules. What started off as a 2-litre naturally aspirated formula morphed into a 1.6-litre turbocharged class.

Fortunately, help was at hand from the motorsport division of MINI’s parent company BMW, which was able to supply a mildly modified version of the productionbased direct injection four cylinder due to be used in its World Touring Car programme. This took some of the pressure off Prodrive, which was then able to repay the favour by supplying in-car data from its development mules, way before BMW had the engine running in its own vehicles.

AERO PACKAGE At the same time, the arrival of the MINI CAD data allowed the aerodynamic package to take shape. Initial development cars had run off-the-shelf rear wing profiles and blanking panels in the grill to simulate approximate downforce and cooling requirements while the final package was emerging in CFD. Or rather the final packages, because the car is being produced in both WRC and S2000 forms, which allow differing levels of wing development and other aerodynamic tweaks.

Again, the team’s methodical approach paid dividends, with cumulative aero data of years of rallying used to define just how wide the

car’s operating envelope needs to be.

Wild extremes of yaw and pitch are something of a given with a rally driver at the wheel, so the wing had to operate more or less consistently across the whole bewildering range. But there are other, less obvious, requirements to designing the aerodynamic surfaces on a rally car, Eastman reveals: “One of the things that’s often overlooked in rallying is that the drivers don’t keep to the track. If there’s a short cut they will take it, regardless of what later turns out to be a ditch or a rock in the way. If you rip off the front bumper, for example, then that’s 100 N of downforce you’ve lost for the rest of the stage. It has to be extremely robust, and engineering that is arguably the hardest part of the bodywork design.”

By the autumn of 2010 the testing schedule was well underway and the MINI John Cooper Works WRC as it was now known had been unveiled to the public.

Another series of endurance tests were to come in France, Spain and Portugal in the first months of 2011, and now barely a month stands between the MINI and its WRC debut on the Rally d'Italia in Sardinia.

Beyond that, only time will tell if it can go on to replicate the success of its illustrious predecessor, but one thing we can be sure of is that it’s an innovative and thoroughly modern take on the design. RT

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AERODYNAMICS CASE STUDY TOP FUEL DRAGSTER WINGS

Generating 5,500 lbs of downforce, while subjected to severe vibration and sheets of flame reaching 980 degrees C…

...IS THIS THE ULTIMATE TEST FOR A WING?

By Chris Pickering

S

PEED; it’s the one thing that motorsport is all about really. Ultimately, for all the ground-breaking science and technology that goes into it, the purpose of racing is to cover ground faster than the next man. And if he happens to be in a Top Fuel dragster this puts you into a whole world of superlatives. To those – like me – used to road racing, the headline figures generated by dragsters are borderline surreal.

A typical NHRA (National Hot Rod Association) Top Fuel car crosses the line at around 325 mph (523 kph) – nearly 100 mph quicker than the fastest speed yet recorded in a Formula One race. But even more impressive is the way it gets there. Top Fuellers can accelerate at over 5 g, passing the 100 mph (160 kph) mark in 0.7 seconds and exceeding 280 mph in a space of 660 feet (200 metres). True, they’ve got 8,000 or so horsepower to play with and corners aren’t really an issue, but the performance is, nonetheless, staggering.

In fact, I’m still trying to wrap my head around the figures while Craig McCarthy of Aerodine Composites tells me about the new front and rear wings that the company has developed for this insane sport. There’s something faintly amusing about the degree of nonchalance he applies to it. “These cars are reaching about 324 mph at the end of the run, but we assumed a speed of 300 mph for a lot of the calculations, because this is the last zone where the downforce is really important to carry the car through to the finish,” he comments with the sort of relaxed enthusiasm that makes it all sound routine.

At this speed the rear wing alone produces about 5,500 lbs of downforce and generates around 1,000 lbs of drag. Its primary job is to create enough traction to transmit the vast torque developed by the supercharged Chrysler Hemi-derived V8. Even at 300-odd miles an hour the tyres are spinning slightly and the rear downforce is an important part of the setup procedure. Beyond a

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certain level of slip the grip breaks down and the tyres go into an oscillation known as tyre shake. The trick is to provide enough downforce to prevent this, without inducing too much additional drag, but it’s not always easy.

“If you’ve got a change of surface, say from concrete to asphalt, part way down the strip it can trigger a loss of traction,” McCarthy explains. “You also get little bumps and imperfections on each track, and it’s not uncommon to get patches of oil laid down if the car before has had an engine failure. In any of these cases the crew chief may choose a more conservative setup with more wing on the car to provide more downforce.”

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where they have to increase it to counter the reduced air density. And, likewise, the development of the wings themselves has traditionally progressed at quite a leisurely rate, with the NHRA, the sport’s governing body, keeping a careful eye on costs. It wasn’t an area that had seen much new blood for a while, but that all changed with the arrival of Aerodine Composites.

SURPRISING CFD RESULTS “Until recently the market only had one source for wings. It’s a fairly small operation here in the States that wasn’t able to keep up with demand and we’d been approached several times to produce wings for the sport,” McCarthy recounts. “The market has always been pretty small commercially, and it’s never going to be a huge money-making operation, but eventually we decided to have a go at a quick CFD study – just to get an idea of how much potential there was to improve upon the current solution at a sensible cost. We were surprised at what we found out.”

Although it was immediately apparent that the potential existed to improve upon

As close to freestream as you’ll ever get in practical aerodynamics”

ABOVE Aerodine Composites has made a record-breaking entry to the world of Top Fuel drag racing While the rear wing is – to quote McCarthy – all about brute force and downforce, the front requires far more finesse. The job of marshalling the immense forces at work means the cars never go down the track in a completely straight line, and the drivers constantly have to apply small steering corrections as they go along.

If the car is running too much wing it can make the front end very darty, which can result in the driver struggling to keep up

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with the steering inputs. This causes them to weave down the track, scrubbing off speed and potentially losing control.

Unlike the rear, the teams don’t tend to adjust the front wing a great deal. Once they’ve reached a sweet spot, where the car is sufficiently responsive to steering inputs without becoming unstable, the crew chiefs tend to more or less leave it there. The only real exception is when they go to a very high altitude track like Denver, Colorado

the previous wing designs, the Aerodine Composites engineers didn’t have it all their own way. In order to get major components such as wings or fuel injectors admitted into NHRA Top Fuel drag racing you first have to seek approval from the association’s technical committee. The idea behind this isn’t to enforce a spec series, but rather to keep costs under control by ensuring that no one product can become a costly must-have.

With this in mind they had to tread carefully, but the engineers sought to come up with a solution that offered useful gains over the old design without contravening the NHRA guidelines. Specifically, it needed to be a three-element design (featuring a main plane and two flaps) that fell within stringent surface area tolerances and passed a test for structural deflection.

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Having come up with an initial proposal for a rear wing they carried out a CFD study and took the results to the technical committee. Despite fulfilling the basic criteria there was still a fear that the Aerodine Composites design would be too radical, McCarthy recounts: “The NHRA technical committee thought the performance difference would be too big a step up from the current designs, particularly given that we were proposing to come in with Al-Anabi Racing, which is one of the biggest teams in the sport. The drag figure, in particular, was a lot lower than before, so we were asked to come back with something closer to the current wings.”

With the aero data he’d taken from the study of the existing wing as a template, McCarthy set about designing a compromise that would tone down the initial proposal yet still offer improved drag characteristics over those currently on the market. And it turned out to be quite a

ABOVE NHRA guidelines stipulated a three-element rear wing. A redesign was necessary after the initial CFD study indicated too big a reduction in drag for the sanctioning body’s liking

ABOVE The project was performed exclusively in CFD (this is a pressure distribution plot for the rear wing), leaving designers ecstatic when drivers revealed that they loved the improvement from the very first pass

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BELOW A lot of the CFD work went into remodelling the endplate design to minimise drag-inducing vortices. The new wing offers in the region of an 11 per cent drag reduction

drastic redesign: the flaps and endplates remained the same, but the main element had to be totally remodelled, sending the project back to the drawing board (or rather the computer).

The entire development process was carried out with CFD. This helped to control the costs compared to wind tunnel

testing, and in this instance McCarthy believes it was every bit as valid. Because the target figures had been generated by a CFD model using the same techniques any small errors with the correlation would have been the same for both tests. “In this case we could rely on comparative results even without physical tests to validate them,” he comments. “It’s actually very much the same situation you get in a wind tunnel. You can compare them to one another, but experimental results can’t be guaranteed to correlate with real world findings there either.”

In both studies he modelled the wing in isolation. It sits so far up in the air that McCarthy reckons it’s about as close to freestream as you’ll ever get in practical aerodynamics. Even without modelling the rest of the car’s geometry, the runtime of the simulation was between 12 and 14 hours for each study, and the computing power required to model the rest of the car would have forced Aerodine Composites to outsource the work. This would have added cost and complexity to the project, which, given the near-ideal airstream meeting the wing, was deemed unnecessary.

One of the primary issues that McCarthy had identified with the existing design was the generation of large, drag-inducing vortices at the rear. “If the humidity is high enough you can actually see them spiralling off the current wings with the naked eye – particularly at high speed,” he explains. A lot of work went into remodelling the endplate design to minimise these, and it’s said to account for a large part of the drag reduction, which totals around 11 per cent over the current offerings.

Once the work was progressing on the rear wing, Aerodine Composites began looking at a solution for the front end, and here it

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encountered one of the unique challenges posed by dragsters. As the cars launch off the line, the torque reaction to the engine causes them to twist noticeably along their axis. In fact, so severe is the level of flex that it can actually pull one side of the wing out of ground effect, while pushing the other further down. To compound matters, while the wing is 62.5 inches wide, it’s mounted on centres just two inches wide, which means that a small oscillation can easily magnify itself. Apparently it’s not unknown for the cars to rub off the bottom of the endplates over the course of a few runs for precisely this reason.

The problem this poses is partly an aerodynamic one – ensuring the wing will remain stable over a range of attitudes – but also a structural one. Part of the problem, McCarthy believes, is that the natural frequency of previous designs has been close to that of the torsional oscillations which occur along the chassis. When the two coincide they effectively go into resonance, making matters far worse. One of the ways he sought to address that was by careful design of the wing’s internal structure. Altering the properties of the spar within it, McCarthy could change its natural frequency and push it away from the harmonics of the chassis.

The same structural idiosyncrasy leads to another very strange effect: dragsters are perhaps the only cars to push the front wing down during acceleration. The back end squats to a certain extent, but, rather than pitching the front skywards, the flexibility of the chassis simply allows it to bow in an arc, BELOW The rear wing operates in a savage environment, enduring brutal shock waves from the header pulses

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While the rear wing is all about brute force and downforce, the front requires far more finesse”

BELOW Changing the flow between the three elements of the rear wing was a crucial juggling act

pushing the middle part of the car into the air and angling the nose down.

Unfortunately this, along with the rising airspeed, tends to increase the level of downforce along the run, when arguably you want it to bleed off. Meanwhile, the same effect increases the rear wing’s angle of attack, upping the downforce. Or at least it does until tyre shake sets in, at which point the expanding diameter of the rear wheel can push the back end up, reducing the rear wing angle; all of which means the wing has to be designed to operate

consistently over a wide range of angles.

Similarly, McCarthy wanted to provide a greater degree of adjustability than the teams could get with the current wings.

“Typically the teams used to have only two or three different positions – relative to the main plane – in which they could run their flaps, but our wing has eight,” he explains.

“We’re supplying them with aero data for those eight options as well as documenting the effect of rotating the whole assembly through a range of angles, so the teams have a lot more to work with. Knowing we were going to provide that level of adjustment it was important to find that sweet spot whereupon the wing would function across the whole range. It turned out this was a fairly difficult thing to do.”

With a three-element wing the top flap has a very steep angle of inclination, McCarthy explains, which means it’s always on the verge of simply turning into a large spoiler.

Aerodine Composites wanted to make sure there was consistent flow across all three elements of the wing, but early on in the testing it discovered the top flap was liable to go into stall.

“It’s really all about positioning,” McCarthy explains. “As you move the various elements of the wing you end up changing the gaps between them, and they can become ineffective if you go too far in either direction.” And yet, with careful

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control of this, he believes he’s found a good balance, that allows all three elements to function in a large variety of different attitudes and environmental conditions.

One thing you can’t overcome, however, is the savage environment the wing has to operate in. The shock waves from the header pulses are brutal, contributing something like 800 lbs of downforce simply from the thrust as they’re fired upwards out of the exhaust.

Unburnt nitromethane flash fires when it encounters the oxygen in the air, sending sheets of flame, which reach nearly 1,800˚F (980˚C) by the end of the run, towards the wing. And that’s assuming all goes well. The superchargers are driven by fabric belts, which have a habit of detaching themselves and hitting the leading edge of the rear wing on the way, plus it’s quite common for the timing cones at the side of the track to be collected if the cars get out of shape. Both are relatively minor issues on their own, but ones that could become disastrous. “At 324 mph anything becomes a projectile,” comments McCarthy. “The risk is that a small impact to the front of the wing could propagate through the structure of the wing to cause a massive failure and a sudden loss of downforce.”

ABOVE Kevlar reinforces the leading edge of both wings (this is the front) LEFT The final wings had to fall within stringent surface area tolerances and pass tests for structural deflection

STRUCTURAL CHALLENGE By far the biggest structural challenge is simply the vibration, however. When the car goes into heavy tyre shake it can have catastrophic results for both the car and driver. In 2007 Funny Car racer Eric Medlen sustained a fatal brain trauma caused by the force of oscillation when his car went into tyre shake. A report later concluded that the deflating tyre had led to an oscillation of 18 inches, exerting a force of over 40,000 pounds (20 tons). And while the driver is clearly the most important component in the car, the sheer magnitude of the vibration is even greater for the wing, which sits on top of a seven-foot tall pylon, acting like a giant lever arm.

All this means the structure of the wings and the materials within them are far more complex than you’d ever guess from the outside. Aerodine Composites uses a blend of two different types of carbon fibre in the designs: Toray T300 3k bidirectional prepreg fabric, which has a lower tensile strength but rather more flexibility, and a T700 material that’s stronger but ultimately more brittle. All the surface plies that need to be robust are manufactured from the T300 material, but the load-bearing inner plies are made from Toray T700 unidirectional tape. Kevlar, meanwhile, is used extensively, particularly in the leading edge, where it protects against impacts and serves to hold everything

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together in the event of a failure.

Much of the structure is actually metallic. The mounts that come out the wing are made from aircraft-grade aluminium and they sit on a chrome-moly steel tree structure, while the spars are a mixture of carbon and aluminium, paired with carbon fibre ribs.

This rather eclectic mix of materials performs well structurally, but it does make the task of stress analysis somewhat more complex. “There aren’t many companies that can actually model composite structures effectively and each one has its own approach,” says McCarthy. “Where we have an advantage is that we can manufacture and test the products in-house to validate the FEA results.” Nonetheless, he maintains it’s not a black art: “Basic shell modelling works wonders for composites, but you do need to give it the appropriate amount of input ... We’re not dealing with isotropic materials here at all; they display totally different properties in different directions, so you have to know exactly how they behave – that’s the important bit.”

Aerodine Composites produced two CAD models of the wing. The first featured all the appropriate material thicknesses and representative gaps for adhesive, to be

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used as a guide for manufacturing purposes.

The second, for FEA modelling, represented the aluminium components as they would be manufactured, but approximated the composites to a series of mid-plane surfaces.

This meant McCarthy could model the individual plies separately and assign different FEA properties to each one.

“There are some FEA packages out there that will take your ready-tomanufacture surface and apply a composite laminate to it, but I prefer the control you get from modelling the plies separately,” he comments. “It becomes extremely important when you have a mixture of different materials, and particularly where you choose to reinforce certain areas (like the leading edge of the wing). We have quite a lot of additional plies to consider on the leading edge, including the Kevlar ones.”

After another anxious meeting with the

NHRA the rear wing was given the goahead. The first example was passed to the Al-Anabi team, along with extensive aero data generated by the CFD simulations.

47

effectively validated all our work.”

It was with this wing that Larry Dixon won the 2010 Full Throttle Drag Racing Series, and yet the process continues. The next step has been to finalise the design and production of the front wing. This uses very much the same principles and construction as the rear wing and builds on the test results collected in 2010. On its first outing with both wings, at the NHRA Winternationals event in Pomona, California in February, the car established a new national ET record, covering the 1,000-foot course in 3.77 seconds and crossing the line at 327.03 mph. With that, it seems, McCarthy and his colleagues have achieved what they set out to do, but the quest for speed goes on. RT

So severe is the level of flex that it can actually pull one side of the wing out of ground effect” “When the team first began testing we were already able to supply the relevant aero data and suggest a starting point for the front wing angle,” McCarthy recounts. “They went out with those settings and the driver loved it on the first pass. We were ecstatic about that, because the wing was designed exclusively in CFD and we never backed it up with any wind tunnel testing. That

ABOVE Al-Anabi Racing’s Top Fueller ready for action. Vibration represents the biggest structural challenge

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ENGINE TECHNOLOGY RACE ENGINE DESIGN PART 5

VALUABLE LESSONS John Lievesley examines air springs and investigates cam profile design

W

HILE SEARCHING for potential partners to manufacture our air springs at TWR, I learned a valuable lesson. We expect specialist suppliers to always keep the design details of their customer’s components secure (rightly so – it would certainly not be worth their while to do otherwise). However, if you present them with carefully reasoned and original design schemes of your own, in which they may reasonably expect to be involved later as suppliers, then you can often get guidance such as, “We don’t think that the problem that you have solved actually exists.” Oops!

If all they do is to avoid you wasting further time refining your solution to a nonexistent problem or send you, without any

detail prompting, to look for an alternative solution, then I don’t have any moral problem with that. However, I do have a problem with people who, under the guise of friendship, tell me the details of a competitor’s designs. I can guarantee you that these information traders will be just as free with passing my secrets to others.

Anyway the outcome of this was that we were advised that my misgivings about the use of moving seals were unjustified and I made a redesign which used them. We had cylinders delivered that were machined perfectly, even close to the bottom of their near-blind bore and seals that did not tie themselves into knots at way over our original (wire spring) 13,800 rpm. The latter were machined from solid PTFE in

the West Country by a company well known for their aircraft strut and classic motorcycle front fork seals, since absorbed by a conglomerate.

I guess that this made me unwittingly guilty of ignoring one of Keith Duckworth’s golden rules: always ensure that you are seeking to solve the right problem. In this case I felt excused by having designed around a potential problem, even if with hindsight it didn’t exist. Later on TWR’s F1 engine, I decided to revisit static seals and produced a worthwhile reduction to the moving mass as well as pleasing the engine builders who found the later system more easy to assemble.

We then had to dream up an air feed control system. I recall that the most well-

ABOVE & BELOW Above, bucket followers, pistons and cylinder from an early Hart engine on which the author worked. The moving seal would slide up and down the internal bore of the cylinder, making it relatively difficult to produce. Below, the rocker assembly, cylinder, piston and valves from TWR’s stillborn P600 F1 V10, a clean sheet of paper exercise for the 3-litre era. Note the piston is much lighter and has minimum wall thickness with an inner stiffening ring at the end where the skirt is longest. At the top, the diaphragm is close to the end of the skirt, removing the requirement for an additional ring and so reducing mass. The working surface is on the outside, making it easier to control the shape and finish

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46.00 mm

FIGURE 1 32.00 mm

R14.581 mm 30.00 mm

R14.809 mm

31.532 mm

Exhaust Limitation #1.

1.341 mm Swept radius 26.831 mm

Swept radius.

22.309 mm

156.000 mm

known ‘off-the-shelf’ version at the time used sets of tiny ball valves etc that reminded me of watch making and just did not appeal: definitely not a product of my ‘Keep it simple’ doctrine.

Two questions: • Why was it so complex?

• Could we design something more simple and hence more reliable? Not that I had any evidence of lack of reliability, I just did not like the complication.

decided to leave the ‘small orifice’ permanently open to the log, biasing the direction of flow through it by machining a trumpet form at the log end and a sharp edge at the spring chamber end. Hence due to the difference in the discharge coefficients, flow into the cylinder was favoured. I arrived at this by calculating the spring’s P/V diagram [pressure vs volume] that would result and matching this to our prediction of the forces required to close

One of Keith Duckworth’s golden rules: always ensure that you are seeking to solve the right problem” Back to my bicycle pump analogy: imagine the cylinder communicating at its base, via a small orifice, c. 0.8 mm diameter, to an air feed log that was gun drilled along the length of the cylinder head. The log was fed from a high pressure (c. 200 bar) storage bottle of about half a litre capacity, via a pressure reducing valve adjustable to around 15-20 bar. Pressure in the cylinder acting on its piston created the closing force on the engine’s valves. I

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the valves. Later real P/V diagrams taken on the cylinder head test rig at TWR closely confirmed our predictions. Most satisfying of all, our springs worked ‘out of the box’ without significant air loss. Self congratulation is out of order as, having arrived late to air springs, the sealing technology was already proven.

At the prototyping stage, I did have a fallback scheme for a tiny on-board compressor in case the storage bottle was

not large enough to cope with the leakage.

But, fortunately, this was not required.

The above mention of the cylinder head test rig at TWR reminds me of my amazement when we first ran it.

Subjectively, there seemed to be very little difference in the sound intensity produced by a complete V10 engine on the test bed compared with that of a cylinder head assembly from the same V10, mounted on a flat plate and having open holes where the cylinders would normally go. We drove it with a variable speed electric motor through the normal speed range of the engine, to investigate valve gear dynamics.

We did not have any reason to attempt to reproduce port flow. An instrumented objective test might have been very interesting, but as noise level was not a priority for our development programme it could not have been justified.

I had previously imagined that an engine’s intake noise was produced by air entering the engine under the persuasion of the piston displacement, creating a series of pulses recognised by our ears as noise.

However I can assure you that an individual motored head assembly, without the help of a block assembly to create pulses,

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generates a prodigious noise level.

Long experience of Lotus Twin Cams and Ford BDAs in rally cars had satisfied me that a significant part of the total noise from an engine emanates from the inlet side.

However, I remain amazed that the noise from our rig was so intense. Maybe the disturbance of the air by the valves reciprocating at one end of the inlet port was sufficient to set up a resonant pulse system in the port and hence the noise?

Because the designed lift of the inlet valve is generally greater than that of the exhaust valve, and the masses of the valves and their associated moving parts, inlet to exhaust, are not necessarily the same, the springs have to be designed separately. Based on experience we might expect an ‘on-seat’ force of 40 kg combined with a force at maximum lift and high speed of around 140 kg. The onseat force is controlled by the pressure in

Scheme your component to be comfortably adequate and let FEA remove unnecessary mass later” Can anyone offer a more likely explanation?

As a ‘minnow’ operation, it was flattering when we occasionally received advice from one of the big boys. For instance we were alerted to a potential problem by the principal of a much larger F1 engine supplier: he told us that they had found that oil inevitably found its way into their springs down the cylinder walls and that we should therefore ensure that it also had an escape route. If oil is allowed to collect, the clearance volume inside the spring is reduced; the compression ratio increases and causes excess pressure and force, or in the worst case hydraulic lock. Either way, the spring can suffer and perhaps the nose of the cam lobe will be wiped off.

A solution whereby the air feed log doubled as an oil drain log and emptied into an external catch pot was schemed.

This was to be ECU-controlled by a solenoid valve which opened to the catch pot, to allow a timed blast of air to pass along the length of the log, scavenging it as it went. Fortunately our springs never suffered excess pressure and we therefore never needed to develop this complicated solution.

the feed log to be sufficient to resist closing rebound, while the increase in spring force with increased lift is a function of the compression ratio and the rate of leakage back into the feed log. Clearly the volume of leak back will vary inversely with engine speed, a desirable feature inherent in this simple design.

The cam profile design originates from the required valve motion. In principle this consists of a short burst of high value acceleration, taking the valve quickly from zero velocity in the on-seat closed position, to maximum opening velocity (positive); this is followed by a long smooth deceleration through maximum lift (zero velocity) to maximum closing velocity (negative) and, finally, a short burst of high value acceleration to gently lower the valve back onto the on-seat closed position. The peak values of the acceleration periods as designed will be at least 6,000 g, overlaid on top of which will be the effects of torsional vibration of the crankshaft, the camshafts and the drive train. Collectively these lead to the rocker arm needing to be able to support say 8,000 g and therefore a design

FIGURE 2

requirement for it to accept say 10,000 g.

For those of you who did not train as professional engineers, fear not, the mathematics of simply supported beam stresses and deflections are well documented and readily available and the masses of the moving parts can be obtained by weighing samples, or derived from the CAD models. I have to admit to generally taking the lazy way out by knowing what has worked for me in the past and then comparing my perception of the new duty with the old. Once again this is perfectly adequate for scheming the initial design because it will be optimised using Finite Element Analysis (FEA) at a later stage.

In principle, scheme your component to be comfortably adequate (within reason) and let FEA remove unnecessary mass later, as reducing the size/mass of a component is generally not an embarrassment. Conversely, having to strengthen something, usually by the addition of material, only to find that you do not have the required space, is a most definite embarrassment. Hence the rocker arm that you see in Figure 1 (from Article #4) is a representative sketch, based on experience, which will require final FEA tuning. See later paragraphs detailing cam design methods to obtain the input data required by the FEA. For instance, the forces and the positions at which those forces are applied to the rocker.

CAM PROFILE DESIGN Let me take you on a journey through the development of cam profile design (see Figure 2). If we could, we would open each valve instantaneously, i.e. with infinite acceleration and velocity, generated by infinite force, up to the maximum useful lift for the valve and port combination as determined on the flow bench. The opening and closing points would be

Max. lift.

LIFT. -65º Say.

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R7.2029 mm Ref.

FIGURE 3a 15.00 mm

140.0ยบ

R15.00 mm

FIGURE 3b

15mm

LIFT. 0

-70ยบ

Cam rotation.

70ยบ

.374 mm/ยบ

FIGURE 3c

0

-70ยบ

Cam rotation.

70ยบ

Velocity.

To Infinity.

FIGURE 3d

Acceleration.

-70ยบ

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70ยบ

determined using engine performance predictive software. At the predicted time, we would shut the valve instantaneously, i.e. with infinite deceleration producing infinite negative velocity, again generated by infinite force. The resulting lift curve would be rectangular and clearly impossible because of the requirement to generate infinite values.

Unfortunately, in the real world, using our most advanced materials, components that are subjected even remotely closely to this sort of abuse, break. Golden rule: before you finish first, you first must finish. I donโ t know who originated that one, but they certainly had their priorities right.

Very early designs were created by drafting the lobe shapes with large magnification, say x20 to x25. Drafting paper unfortunately expands and contracts with changes of ambient humidity, hence what you had laboriously produced one day using your best 0.01-inch division steel rule and a Sherlock Holmes magnifying glass had been rendered useless by the time that you returned next morning. We now have the luxury of drafting with CAD and can guarantee accurate and repeatable measurement of lift v angle. Having obtained the lift table, Excel is ideal for calculating the velocity, acceleration and jerk tables by differences.

The lobe shapes were based on three arcs (see Figure 3 a, b, c and d, where I have sketched the most simple of three arc profiles). This has a flat flank (infinite radius), and it is clear that it can only work in combination with a convex curved follower. With a flat follower the offset of the contact line moves instantaneously from the base circle (zero offset and therefore zero follower velocity) to its maximum offset; put simply, the valve is asked to move with infinite acceleration and as above, this is not acceptable.

Study of Figures 4a, b, c, and d, shows that to achieve even vague cushioning of the acceleration phase with a flat follower, the flank must be convex and spread over a cam rotation angle of say 7ยบ to 10ยบ to be in proportion with the total half period of the profile of 70ยบ. Obviously, the shorter the duration of the acceleration period then the higher will be the maximum acceleration value, but attempting to control this by lengthening the acceleration period will increase the values through the deceleration period, which is unfortunately

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ENGINE TECHNOLOGY

FIGURE 4a

R4.093 mm Ref.

Whoever came up with, ‘Before you finish first, you first must finish’ had their priorities right” wholly under spring control, and also reduce the nose radius. A heavier spring (to cope with the increased deceleration values) and a smaller nose radius conspire together to increase the Hertz stress over the nose of the lobe, so follow that route at your peril. I have tested a flank radius of 150 mm, which gives an acceleration period of 9.6º and a nose radius of c.4.1 mm, which from experience is suitable.

Figure 4 d illustrates my chief objection to the three arc concept and I am far from alone in this. Even after the numbers have been smoothed by one of the curve plotting sequences built into my CAD suite (this one is a Bezier plot), the abrupt sign reversal to the acceleration at around 60º is clear. From elementary applied mathematics, we know that to accelerate a body requires a force, hence if we induce a step change to the acceleration of our valve gear system, then we create a similar step change to the forces within that system and also a step change to the dynamically distorted dimensions of the components within that system.

Put another way, strain energy absorbed by a component due to the application of a force, will be released as soon as that force is released. All normal engineering materials exhibit a spring-type reaction to force, characterised by their Modulus of Rigidity.

When they are suddenly released from deflection, they recover through their zero force, zero deflection condition and approach a deflection almost equal in amplitude but opposite in sign to that from which they have just been released. Put simply, they go through the first half of a vibration cycle.

This felony is then compounded when the reverse sign acceleration ‘kicks’ in (pun intended), in phase with the first. The sharper the step, the more severe is the vibration that will result and I hope that my objection is now clear to all.

53

15.00 mm

9.6° R150.00 mm

140.0°

FIGURE 4b

15mm Scale x20.

LIFT. 0

-70º

70º

Cam rotation.

Scale: 1º = 4mm.

FIGURE 4c

0

-70º

Cam rotation.

70º

Velocity.

FIGURE 4d

Acceleration.

-70º

0

Cam rotation.

70º

• Next issue: three arcs made obsolete; profile design by limitations. RT

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ENGINE TECHNOLOGY TURBOCOMPOUNDING

INVESTIGATING F1'S NEW DAWN With a revolutionary change coming to Formula One engines in 2013, Cranfield MSc student Ralph Koyess undertook an assessment of the performance benefits of turbocompounding a 2013 F1 engine for his thesis. Here he explains his findings

I

N 2008, the FIA enforced the controversial 10-year engine freeze in an aim to reduce the running costs of Formula One teams. This regulation prevented manufacturers from developing their engines with the exception of reliability improvements which had to be approved by the FIA. The freeze can only be contested after a five-year period and with the unanimous consent of the teams.

With this five-year period coming to an end after the 2012 season, engine manufacturers are in discussion to change the engines for 2013. The configuration agreed upon is a 1,600 cc in-line fourcylinder engine with an expected rev limit of 10,000 rpm in order to be of more relevance to the production car industry – and as a recent research has revealed, over 64% of cars built in 2010 were powered by a four-cylinder engine. Furthermore, the

fuel flow is expected to be capped at around 25 g/s in order to promote a more environmental image for the sport. With the desire to keep power levels similar to today’s engines, turbocharging and energy recovery systems are expected to be permitted. These regulations present the perfect platform for a long-awaited technology to make its way into Formula One: turbocompounding.

WHAT IS TURBOCOMPOUNDING? Compounding is the use of two or more sources to produce a single output.

Turbocompounding is the use of a turbine as one of the sources and the engine as the other to produce one output: torque at the crankshaft. Its simplest form is presented in Figure 1.

The exhaust gases represented in red are

FIGURE 1 Basic form of turbocompounding

RIGHT Ready to move out of the dark ages? F1’s engine technology has stagnated under the FIA’s engine freeze. The 2013 season offers the opportunity to embrace solutions like turbocompounding

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ENGINE TECHNOLOGY

channelled to the turbine commonly referred to as a power turbine.

The pressure and kinetic energy of the gas spin the turbine and produce mechanical power which is transmitted to the crankshaft through a mechanical linkage, generally a gear reduction.

The more likely scenarios for a Formula One application are presented in Figure 2 and Figure 3.

In these configurations, the exhaust gases are used to power the turbocharger and then routed to the power turbine which recovers further energy from the exhaust. Two setups are possible, the first, presented in Figure 2, consists of mechanically linking the power turbine to the crankshaft and the second, presented in Figure 3, consists of connecting the turbine to a generator that converts the mechanical energy to electricity that can be stored in a battery and then used to increase the engine’s output through a motor or to power ancillaries. This second setup is called electric turbocompounding.

AEROSPACE INNOVATION

55

compounds for their engines.

So why hasn’t it been used in F1 yet? In the late 1980s, during the turbo era, Cosworth worked on a turbocompounded Formula One engine. However, it was advised by the FIA that it would be banned and the project was dropped. Ever since, the regulations haven’t allowed the use of this technology.

HOW CAN AN F1 ENGINE BENEFIT? Engines in general are inherently inefficient and Formula One engines are no exception. Only about one third of the energy input to the engine in the form of fuel ends up as useful power.

One third is dissipated as heat in the cooling system and a third is released in the exhaust. Assuming that a current Formula One engine produces 560 kW, another 560 kW is released in the exhaust. This constitutes a very important source of energy to tap into in order to increase the efficiency and hence the power output of the engine.

In order to assess the performance benefits of turbocompounding a 2013 Formula One engine a full study was completed by the author for his MSc in Motorsport Engineering and Management at Cranfield University. The study involved building a 2013 spec Formula One engine in AVL Boost, a commercial engine simulation software used by various engine

Turbocompounding was first used in the 1950s on aircraft engines.

The most successful application was on the Wright R-3350, an 18cylinder radial engine with a displacement of 54.9 litres powering military aircraft, most notably the Canadair CL-28, the Lockheed P2V-7 and the Fairchild C-119. The fuel mass flow into the engine translated into a 5,650 hp input of FIGURE 2 Mechanical turbocompound on a turbocharged engine which only 1,680 hp resulted in engine power and a significant 2,915 hp or 51.6% was released into the exhaust.

Exhaust energy recovery was therefore paramount and the implementation of turbocompounding increased the engine output by 160 hp.

Other noteworthy applications in the aerospace industry include the Allison V1710 and the Napier Nomad, both of which were developed as test engines but never made it to production.

Nowadays, the technology is being used on large displacement diesel engines for heavy vehicles. The best examples are the Cummins and Scania engines that power many of the freight FIGURE 3 Electric turbocompound on a turbocharged engine transport trucks. In these applications, the aim is to reach a certain power output at a lower rpm and hence reduce fuel consumption. The first successful application was on the Cummins NTC-400, a turbocharged six-cylinder diesel engine with a displacement of 14 litres that produced 400 hp at 2,100 rpm.

Turbocompounding the engine resulted in a decrease in fuel consumption of about 27 g/kW.h over the operating range.

Other manufacturers such as Caterpillar and John Deere are known to have worked on electric turbo

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ENGINE TECHNOLOGY TURBOCOMPOUNDING

manufacturers. The main engine parameters are presented in Table 1.

The simulation procedure consisted of modelling the engine naturally aspirated first in order to obtain a running engine model before adding components and complexity. In order to keep the focus of the study on turbocompounding, most of the parameters of the engine were fixed and only the necessary ones were left as variables to allow the output to be optimised at each stage in the process. The parameters that were left as variables are the inlet and exhaust primary lengths and the intake and exhaust valve lift and flow coefficient profiles. Others such as the ignition timing, camshaft profile, maximum valve lifts and the air/fuel ratio were set to constant values.

The next step consisted of modelling the turbocharger which required the matching of a compressor and turbine that can generate the required pressure ratio across the compressor. The model was optimised to obtain the desired output by varying parameters such as the turbine and compressor map scaling factor and the pressure ratio in addition to the parameters modified for the naturally aspirated model.

The final step consisted of adding the power turbine to the model. A major part in this step was the study of axial and radial turbines to identify the most appropriate one for the application. The axial turbine resulted in less backpressure and was therefore used for the simulations. The final simulation model is shown in Figure 4.

FIGURE 4 Simulation model

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TABLE 1: ENGINE SPECIFICATIONS Configuration

In-line 4

Displacement

1.6 litres

Compression Ratio

12:1

Rev Limit

10,000 rpm

Bore

82 mm

Stroke

75.74 mm

Conrod Length

143.5 mm

Mean Crankcase Pressure

100 kPa

A/F Ratio

13.965

Fuel Consumption

25 g/s

Firing Order

1, 3, 4, 2

FMEP at 10,000 rpm

2.8 bar

The turbocharger and power turbine are labelled TC1 and T1 respectively. Mechanical turbocompounding was used as opposed to an electrical system. The orange line labelled MC1 represents the mechanical link with a fixed gear ratio between the power turbine and the crankshaft. The results of the simulations are presented in Figure 5. The turbocompound engine performance is plotted along with the turbocharged engine performance for comparison purposes.

From 6,500 rpm the turbocompound engine produces more torque and power. However, it is only from 8,000 rpm that there is a significant increase in output. The output increases by 26.7 kW and 27.7 Nm on average which represents a 7% power increase and 6% torque increase in the range where the engine spends over 85% of its life. There is a peak increase of 31.5 kW and 31.7 Nm at 9,500 rpm. At the most useful speed, 8,500 rpm, there is an increase of 26.5 kW and 29.8 Nm which translates into a 6.5% increase to both power and torque. Since there is an increase in power for the same fuel consumption, the BSFC is lower for the turbocompound engine. It is important to note that the gear ratio of the mechanical linkage was optimised to get the highest value possible for the power at 8,500 rpm.

Furthermore, the ratio was the same for all speeds. A higher output can be obtained if the gear ratio is variable and is optimised at each speed.

To measure the efficiency of the mechanical turbocompound system, the exhaust energy is calculated at 8,500 rpm before and after the power turbine. Before the turbine, it is equal to 382.3 kW and after the turbine is 344.2 kW. The difference is 38.1 kW which is the total power absorbed by the turbine. This represents 10% of the energy released into the exhaust. From the 38.1 kW, 26.5 kW end up at the crankshaft which means that the turbocompound system designed has an efficiency of 70%.

Finally, we look at the efficiency of the engine. The turbocharged

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ENGINE TECHNOLOGY TURBOCOMPOUNDING

Adopting such technology in Formula One will surely go a long way to enhance the green credentials of motorsport and in addition develop a technology that will prove beneficial in road car applications.

A 7% power increase and 6% torque increase in the range where the engine spends over 85% of its life� engine without the power turbine has an efficiency of 36.9%. The turbocompound engine has an efficiency of 39% which represents a 2 percentage point increase in efficiency over the turbocharged model. This is quite a significant increase that highlights the benefits of turbocompounding.

While turbocompounding adds power at no extra fuel cost, it adds weight to the vehicle. The mass of the added components to the turbocharged engine is estimated at 16.5 kg. It is commonly known that there is a time penalty of around 0.3 seconds per lap for every 10 kg added to the car. Adding 16.5 kg to the car would theoretically slow it down by about half a second a lap. However, Formula One cars carry 30-50 kg of ballast in order to reach the minimum weight. The weight of the turbocompound system is subtracted from the ballast and the result is a higher centre of gravity. Increasing the centre of gravity by 10 mm will result in a time penalty of 0.1 second. However, the 2010 F1 technical regulations state that the centre of gravity of the engine must not lie below 165 mm and the weight of the engine must be a minimum of 95 kg. If similar regulations are instated in 2013, the engines will be designed around the minimum weight allowable with the turbocompounding system considered part of the engine. The result is that the turbocompound system will not alter the total weight or the centre of gravity of the engine which will always be close to the minimum stated by the regulations.

turbocharged engine. This is ideal if the fuel flow rate is capped by the FIA. The study also revealed that an axial turbine induces less backpressure than a radial turbine and is therefore better suited for this application.

KERS and turbocharging offer a great platform for the development of the electric turbocompound system described in Figure 3.

• This research was sponsored by Cosworth and was completed by Ralph Koyess with the technical support and supervision of Stuart Grove (Cranfield University), Matthew Harrison (Cranfield University), David Gudd (Cosworth) and John Bell (Cosworth). RT

FIGURE 5 Turbocompound and turbocharged engine performance

CONCLUSION Turbocompounding was theoretically proven to be beneficial for the 1.6-litre Formula One engine modelled.

Turbocompounding was found to increase the power by about 27 kW or 7% over the useful range of the engine, from 8,000 to 10,000 rpm. The peak power increase occurs at 9,500 rpm with 31.5 kW or approximately 8% added to the turbocharged engine which results in a 2% increase in engine efficiency. The power increase comes at no additional fuel consumption when compared to the

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LESSONS FOR MOTORSPORT VOLKSWAGEN XL1

THE PEOPLE’S RACING CAR? The XL1’s eye-catching 318 mpg tag impresses the headline writers, but has no impact on motorsport. Or does it? Chris Ellis crunches the numbers and plots a 2013 Le Mans campaign

E

ARLIER THIS year Volkswagen announced the XL1, the third in the L1 series of concept cars aimed at achieving a fuel consumption of less than one litre per hundred kilometres (equivalent to 282 miles per UK gallon). In fact, the XL1 has delivered a headline figure of over 300 mpg on the New European Drive Cycle.

The XL1 is a small two-seat coupe, 3,888 mm long, 1,665 mm wide and just 1,156 mm tall. At 795 kg, it’s roughly the same length, height and weight as a Lotus Elise or Exige. However, the XL1 is a plug-in parallel hybrid with an engine-off range of up to 20 miles, and is fitted with a 47 bhp two-cylinder diesel engine and a 20 kW (27

bhp) electric motor. Even with both running, the XL1 takes 11.9 seconds to reach 62 mph, to which your immediate reaction might be, ‘So what’s this got to do with motor racing?’ However, please take a look at the cutaway of the XL1 glider on the third page of this article, in particular the carbon fibre monocoque, and consider

ABOVE The XL1 concept looks likely to become production reality.

Its appeal could spread from the city to the racetrack

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LESSONS FOR MOTORSPORT

its potential and the implications.

If the XL1 was just another concept car, it might be interesting but it would not be particularly significant. However, VW management has already confirmed that the XL1 will be put into limited production, first for Germany, then elsewhere. A similar powertrain, minus the plug-in capability (to save cost and weight), is likely to appear in the hybrid version of the imminent VW Up! which is expected get some 95 mpg on the combined NEDC cycle. In a direct comparison, the XL1 can achieve 141 mpg running on its engine alone. The benefit of its lower frontal area and superior drag coefficient will become even more obvious when we see the first side-by-side test of an Up! Hybrid and a production XL1, probably sometime in 2013.

My guess is that, running side-byside at a steady 80 mph, the XL1 will use fuel at roughly half the rate of the hybrid Up! (Occasionally, that exclamation mark is entirely appropriate!)

The XL1’s relatively small electric motor and controller should cost less than half the equivalent electrical components in the Prius. The volumes likely to be achieved by the Up! should help to keep down the costs of the XL1’s engine and transmission. Volkswagen has developed a new process for the production of Carbon Fibre-Reinforced Polymer (CFRP) body parts which should help reduce the cost of the monocoque.

The choice of Volkswagen to launch the new technology within a group that includes Audi and Porsche suggests an intention to set a price for the car which will

ABOVE The comic book silhouette of Citroen’s Survolt can’t mask the fact that electric powertrains are likely to become a reality at Le Mans suspension, weighs only 230 kg. Let’s assume the XL1 will have an on-the-road price of €40,000 in Germany. How much might a complete ‘spare’ body cost, and what could you do with it? Even a price as high as €15,000 would be much lower than most other sources of racing survival cells.

Starting with the XL1 monocoque, doors and windscreen, it would appear relatively easy to add a new or modified rear subframe, plus racing suspension and brakes all round.

A longer wheelbase would seem simple to arrange, allowing a longitudinal engine to be fitted. One conforming to the new LMP regulations might be appropriate, perhaps the 450 bhp 2.0-litre Mountune unit featured in the February 2011 edition of this magazine. A less expensive and street-legal transverse alternative might be the 267 bhp lump from a Golf R, complete with its 6-speed dual-clutch transmission. Imagine taking either of these versions to a track day: great fun, and humbling for some.

As new regulations are put in place across

Volkswagen has demonstrated what can be done, and how” generate strong demand, potentially supporting a virtuous circle of further cost reduction and strong profitability. This should then lead to even more interesting models – a ‘baby Bugatti’, anyone?

The XL1’s central tub is moulded from CFRP, as are the ‘wing’ doors and body. The double wishbone front suspension is mounted directly to the tub. The aluminium rear subframe is also bolted to the tub. The complete body, including doors and windscreen but without wheels and

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motorsport to lower downforce, one result will be a reduction in aerodynamic drag, potentially raising top speeds to unacceptable levels unless peak power levels are also reduced. The FIA has expressed a preference for monitored fuelflow metering to limit peak power, rather than air intake restrictors etc. Consequently the most likely powertrain is a fuel-flowmonitored engine supported during acceleration by a surge power unit deriving its energy from a combination of regenerative braking, thermal energy recovery and turbo-compounding. KERS is no longer an appropriate label, as more than kinetic energy will be recycled. The net result should be equally fast lap times, similar top speeds, lower cornering speeds and faster acceleration across most racing series, not just F1.

PLAYGROUND FOR ENERGY RECOVERY Right now, Le Mans seems more welcoming of advanced energy recovery than F1, and the proposed F1 regulations for 2013 are unlikely to change this. Le Mans imposes no artificial and irrelevant limits on the amount of recovered energy used per lap or on

April 2011

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LESSONS FOR MOTORSPORT VOLKSWAGEN XL1

peak input power during braking, both of which seem likely to persist in F1. Le Mans has embraced four-wheel-drive for hybrids, yet F1 seems likely to continue to ban it, despite the compelling logic in its favour for regenerative braking. One probable outcome is that most of the technical solutions that succeed in F1 will prove suboptimal or irrelevant elsewhere, both in racing and in road vehicles. On the other hand, the new Le Mans regulations should provide a nursery for solutions which transfer readily to road cars. Perhaps the nursery already has a place reserved for a baby Bugatti!

An initial and necessarily superficial check against the 2011 Le Mans LMP regulations indicates that the only significant modification required to the XL1 tub would be the addition of CFRP to meet the requirements of clause 16.2.1 b (The survival cell must provide lateral protections 500 mm high as a minimum along the total length of the cockpit opening).

ABOVE & BELOW Cutaways of the XL1. The carbon fibre-reinforced polymer monocoque, like the powertrain, opens up a world of opportunities

NEW GENERATION The XL1 may give ‘gifted amateurs’ the opportunity to explore this new generation of racing without needing the financial resources of a professional team.

Even if Volkswagen decides not to make the XL1’s tub available separately, several others may, eventually. For example, Alfa Romeo is expected to launch a midengined coupe with a carbon fibre tub, in a similar timeframe and for a similar price.

The contribution Volkswagen has already

engine with its 200 kW surge power unit and some 40 kW from other sources (turbocompounding, TEGs, etc) will result in a sustainable 376 kW on the straights and up to 576 kW for surging out of most corners or overtaking. That’s up to 770 bhp per ton, complete with driver. Adequate then.

Driving the XL1 body in standard form, a mere 376 kW (504 bhp) will be enough to exceed the top speed of the Veyron, which

The new Le Mans regulations should provide a nursery for solutions which transfer readily to road cars” made is to demonstrate what can be done, and how.

Imagine now a 2013 Race Tech headline ‘Bugatti returns to Le Mans’. Ettore Bugatti claimed, "Weight is the enemy." Half the Bugattis ever built had four-cylinder engines and weighed even less than the XL1, which suggests Ettore would be mildly ecstatic about our hypothetical XL1-based baby Bugatti, especially its upgraded powertrain.

Combining the 450 bhp of its homologated 2.0-litre turbocharged 4-cylinder boxer

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is probably too fast for comfort in the minds of the ACO and most other mortals, particularly Bugatti management. So here’s the deal: the ACO allows Equipe Bugatti exemption from clause a.3 of regulation 3.6.3 (Rear Wing – not to be adjustable from within the cockpit). This exemption would be in line with the new F1 rules governing ‘driver adjustable bodywork’ from the 2011 season onwards, with the proviso that the default position of the wing should be high incidence (maximum

downforce and drag), and that a positive command from the driver must be received after every braking event to move the wing to the low drag/downforce position. Any failure of the control mechanism must result in a return to the default setting (remember 1955). Bottom line: the extra drag of the wing even in its low incidence setting, plus wider wheels, etc, should be enough to cut the top speed of the baby Bugatti to acceptable levels, while the high incidence setting should be able to provide more downforce in the corners that the fixed wing cars can afford.

The aerodynamic solutions VW has proved in the XL1 plug-in hybrid can also be applied to battery-only and fuel cell vehicles. Minimising the energy they use at highway speeds is key to overcoming their range limitations. The XL1 needs only 84 Watt hours per kilometre at a constant 100 kph. This contrasts with the 133 Wh/km (EPA test) of the Tesla Roadster, which is handicapped by its Cd of 0.35, and the 102 Wh/km of the GM EV1. With the same battery capacity, an XL1 should be able to travel some 60% further than the Tesla, on electricity alone. 84 Wh/km at a steady 60 mph implies that only 5.3 kWh of available battery capacity would be

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LESSONS FOR MOTORSPORT VOLKSWAGEN XL1

ABOVE Porsche’s 911 GT3 R Hybrid has impressed wherever it has appeared, but there are alternatives to the ‘flywheel battery’ arrangement (Photo: Porsche AG)

needed to provide 40 miles of engine-off cruising. The Chevrolet Volt needs almost twice as much available battery capacity (10.4 kWh) to provide a nominal electric range of 40 miles. Even at 75 mph, a cruising speed more likely to be acceptable to most Race Tech readers, 5.3 kWh should still provide an XL1 with an electric-only range of some 25 miles.

The key point here is that low drag isn’t just about saving fuel or electricity; it reduces the cost, size and weight of the battery in any type of plug-in vehicle. So far, most electric cars are merely conventional cars with electric powertrains, or end up with frontal areas compromised by underfloor batteries. It’s when we start seeing Cds below 0.20 that we will know manufacturers are getting serious.

DECISION TIME Mercedes, for one, has already announced this as an objective within five years. The deficiencies of the NEDC and EPA tests help hide the limitations of the current crop of electric and conventional vehicles. On the other hand, the XL1 and its technologies provide a much better place to start (pun intended), whatever the powertrain. The

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board of Volkswagen AG will have some interesting decisions to make. And watch out for the responses of the other major manufacturers, on and off the track.

Of course, a tiny two-seat coupe with limited performance has only a small addressable market. One wag commented that the XL1 was a “Smart done right”.

Another suggested it’s an EV1 without the range anxiety. But what if Volkswagen (and others later) were to apply the same approach to a four-door with the same footprint as a Golf or a Ford Focus? Let’s take a first look.

Really fuel-efficient car designs move the

drivers. But the world moves on, and engines are getting smaller and lighter, particularly in ‘strong’ hybrids.

Let’s refer to our imaginary four-door derivative of the XL1 as the XL4. Porsche has confirmed that it is developing a new 2.5-litre 4-cylinder boxer engine capable of producing some 350 bhp in turbocharged form. The ‘front half’ of this engine could provide a 1.2-litre boxer twin of some 80 bhp in non-turbo form running on petrol, ANG or biofuel. Turbocharged, it should be able to deliver as much as 160 bhp. A diesel derivative for continental Europe might produce some 80 bhp. This engine would

It’s not fair: they’ve been allowed to use 21st century technology!” engine rearwards, from the pre-war Tatras through the Ford Probes, the GM Precept, the BMW VED and now the XL1. However, the last two don’t go the whole way, with the engine placed transversely just in front of the rear axle. This intrusion into the passenger space between the axles is obviously acceptable in a two-seater, but has never really worked in a 2+2, let alone a four-door. Historically, placing the engine behind the rear axle has been a challenge, both to designers and to

have three major advantages over the twin used in the XL1. It would have the extra torque and power needed to propel the XL4. Second, it would be a short, flat, engine under the front of the boot floor, taking the minimum of usable space and helping to provide a low centre of gravity.

Finally, a boxer twin will have much better inherent balance than a straight twin, avoiding the need for the balancer shaft required in the XL1 engine.

The cost and complexity of two cylinder

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LESSONS FOR MOTORSPORT VOLKSWAGEN XL1

heads and their camshafts in the XL4 would be partially discounted by the avoidance of a balance shaft and its drive.

The engine in the XL1 was developed with transverse front-engined applications in mind. However, here we are conforming to the logic pursued by Dr Porsche in designing the original Beetle, but this time we have the additional mass of the surge power unit to accommodate, which has the potential to balance the mass of the engine if placed correctly.

Because staggered seating no longer makes sense in a four-door, the XL4 needs to be wider, say the same width as the Golf, 1779 mm. This then allows space for a transmission tunnel containing a propshaft connecting the main transmission to the surge power unit located at the front of the tunnel. With a rear engine, the tunnel has only the propshaft to contain, so it can be relatively low and narrow, enabling a realistic fifth seat. With a 60 kW surge power unit delivering a peak torque of over 200 Nm the XL4 should be able to reach 60 mph in less than 12 seconds using surge power alone. This should improve to less than eight seconds with the basic engine

running as well, and under six seconds with the turbocharged engine.

Bringing the length of the XL4 up to the 4199 mm of the Golf could add over 300 mm to the wheelbase without changing the overhangs. At 2535 mm, think of a 911 with seven inches of extra legroom, making 4/5 seats credible. Make the height 1300 mm; that’s halfway between an Audi R8 and a TT, and typical of a 911 but slightly taller than an EV1. I don’t remember complaints about lack of headroom in any reviews of these cars. Clearly, the frontal area will have increased significantly, probably from 1.50 to around 1.80 square metres. If anything, the Cd should improve slightly, given the significant increase in length, perhaps to 0.183. The Cd of a basic Golf is 0.312 and the frontal area is 2.22, giving a Cd.A of 0.693. This contrasts with a Cd.A of 0.227 for the XL1 and some 0.333 for the imaginary XL4. Given that the XL1 requires only 8 bhp at the wheels to maintain a steady 60 mph, an XL4 shouldn’t need more than 12 bhp to keep the same speed. Extrapolating to higher speeds, the XL4 should require only 30 bhp to cruise at 80 mph, and 100 bhp to

maintain 130 mph. So even the base models should be able to reach 115 mph and cruise all day at over 90 mph.

Now imagine taking an XL4 with the 160 bhp version of the street engine, upgrading the suspension, tyres and brakes and fitting it with a much more powerful surge power unit, say 200 bhp (150 kW). Easily done, and not that expensive. Then run it round to the British Touring Car Championship committee and watch their faces. Hopefully, they will love it, and let you race it, despite the objections of most other competitors.

“It’s not fair, they’ve been allowed to use 21st century technology,” etc.

FLYWHEEL BATTERY Porsche has already won races with the 911 GT3 R Hybrid using a flywheel rather than a battery. However, there are alternatives to the Williams ‘flywheel battery’ Porsche has used. Potentially more efficient is an allmechanical toroidal CVT of the type Nissan used in a Japan-only premium version of the Skyline. However, using this type of CVT would require an additional electric motor to be fitted to take advantage of the

ABOVE & RIGHT Manufacturers like Peugeot, whose Hybrid4 prototype supported the launch of its first diesel hybrid road car (right), are quick to exploit the marketing links between track and road offered by the Le Mans 24 Hours. The regulations offer the hope that a genuine technology flow could develop too (Photos: Peugeot)

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LESSONS FOR MOTORSPORT

electrical energy flowing from any TEGs and/or turbo-compounders. This additional motor and controller would not be needed with the Williams system. The ideal system would combine the advantages of both approaches, without the disadvantages.

While the standard XL1 is rear-wheel-drive only, the racing 911 Hybrid is four-wheeldrive, but with no connection between front and rear; the engine drives the rear wheels and the flywheel drives, and is driven by, the front. In racing, maximum benefit from regenerative braking requires all four wheels to recover energy; if this is not allowed, using just the front wheels is more effective than using just the rear wheels. The ACO recognises this, and has begun to frame the LMP1 regulations appropriately. Let's assume it relaxes the current restriction of ‘front or rear axle but not both’ by 2013.

The system in our imaginary baby Bugatti is more sophisticated than the current Porsche approach, with surge power and regenerative braking available at all four wheels. As in the XL1, a slim axial motor/generator is sandwiched between the engine and the main transmission. The

power as the driver’s right foot signals (via some sophisticated software, naturally). The generating torque of the front motor/ generator has the dual effect of slowing down the sun gear and flywheel, extracting energy from it, and speeding up the planet carrier and front pinion. Conversely, the

ACO regulations specifically encourage the flywheel (or battery) to be placed in the passenger footwell, inside the survival cell.

In this configuration the flywheel drives the sun gear of a planetary gear stage, and the planet carrier is connected to the pinion of the front differential. The ring gear is free to rotate, but is directly connected to the rotor of a second motor/generator.

During acceleration, the front motor/generator acts as a generator, supplying the rear motor with as much

over the approach currently used by Porsche? Let’s assume a need to provide 120 kW of surge power in addition to that of the engine. Porsche achieves this with a 120 kW Williams flywheel and two 60 kW motor/generators (each driven by and driving one of the front wheels), a total of 240 kW of motor/generators and their controllers. The proposed Bugatti system could achieve the same net power with only two 60 kW motor/generators. The obvious cost savings may not be too

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significant in a Bugatti, but they will certainly become significant when the system moves down to Audi and Volkswagen. This fundamental advantage should encourage the adoption of the Bugatti solution throughout the VW Group.

In addition, the Bugatti system should

The opportunity to explore this new generation of racing without needing the financial resources of a professional team” front motor/generator acts as a motor during braking, receiving electrical energy from the rear unit now acting as a generator helping to slow the rear wheels.

The car is slowing so the planet carrier must also slow down. This effect, combined with the front motor’s torque being applied to speed up the ring gear, must speed up the sun gear even more so, thus transferring some of the kinetic energy of the car into the flywheel rotor.

So what are the advantages of the hypothetical ‘Bugatti surge power system’

prove more efficient. Approximately half the energy flowing in and out of the flywheel will be transferred directly via a simple planetary gear set, more efficiently than by any other possible means. The rest of the energy will be transformed into electrical energy and then back into kinetic energy, twice in a full regenerative cycle. In contrast, all the energy in a ‘flywheel battery’-based system has to be transformed in this less efficient manner.

A toroidal CVT-based system might prove more efficient than a ‘flywheel battery’ but it is unlikely to improve significantly on the proposed Bugatti system because its mechanical pathway will be less efficient than the planetary gear set of the Bugatti approach, to the extent that the toroidal system’s savings relative to the Bugatti’s 50% electrical pathway are at least partially offset. The toroidal approach also requires the weight and cost of a mechanical connection to all four wheels to achieve the four-wheel-drive necessary for full racing efficiency, and it also needs an additional electric motor if the vehicle has other forms of energy recovery with electrical output and/or it needs to support a plug-in battery.

In summary, the hybrid electrical/ mechanical surge power unit proposed for the baby Bugatti is also ideal for plug-in hybrids, fuel cell vehicles and even ‘batteryonly’ cars. Where Bugatti leads, others will follow. Maybe...

• Chris Ellis is the CEO of HyKinesys, developers of the PowerBeam surge power unit. The Oak Ridge National Laboratory recently published a safety assessment of the PowerBeam rotor design, funded by the U.S. Department of Energy. For racing applications, please contact Hewland Engineering. RT

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PRACTICAL RACER 750FORMULA BUILD PROJECT PART 12

SITTING COMFORTABLY? Graham Templeman and Rod Hill need a seat for their 750Formula racer before the gear linkage and lever can be installed. Will they just go and buy one? Not likely, is it?

S

OMETIMES it does not feel like it, but there really is a plan for how we are going about building the T5.

Phase 1 was building the chassis; Phase 2 involves installing the various systems in the cockpit; and Phase 3 had been to set up the Templeman garage as a composites shop in order to make the moulds and to manufacture the bodywork as soon as the chassis was available to model its new clothes. While this is happening, Rod will turn his attention to building the engine and sorting out the driveshaft situation.

We have realised, though, that we need a driver’s seat so that the controls can be properly placed. Pedals are not much of a problem, but we need to install the gearchange and linkage, make a dashboard to house the AIM Pista dash (can’t afford the Professional model), fit seatbelt mountings, brake balance adjuster, headrest and all the dozens of little things that have got to be within easy and comfortable reach for the driver.

The gear lever and linkage is a major issue, because we have to grapple with fitting a lever into the cockpit without it intruding into the passenger space. This has never been a problem for the front-engined cars because the lever sat on the transmission tunnel. But we get the benefit of being able to move the driver further towards the centre of the cockpit (to help balance out the side-to-side wheel loadings), which in turn moves the gear lever further to the left and there is the possibility of intruding into the passenger space. Unfortunately the

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BELOW Stage 1: the profile of the seat

passenger space dimensions are quite complex; the extract below is only a part and the club guards them very jealously so that any contravention would outlaw the car.

The passenger space, exclusive of the seat structure if fitted, measured at floor level must be at least 27.9 cm (11 in) wide at the rear of the cockpit and at least 70 cm (28 in) in length to the front of the footwell. The footwell must be at least 15 cm (6 in) wide and 25.4 cm (10 in) high.

These dimensions must be maintained over this area.

There is also a bit of a hidden agenda here because we have realised after looking at photographs of Martin Kemp’s new car that we could move the fuel tank forward into what we had originally planned to be

a part of the cockpit. This would make a significant contribution to moving the centre of gravity to where we want it and take the heat off having to cram as many of the minor components as possible into the front of the engine bay.

As an aside, we are not the only people building cars to the new regulations. Martin intends to offer replica kits for his car just as soon as he has had the chance to race it and prove its worth and there are another three under construction that we know about and we have suspicions about at least one more. There is also the new class for college-run cars that will no doubt yield a few more in the slightly longer term.

So Phase 3 has kicked in a little early. We need a seat. The one on the current car is a cast off from a single-seater and is asymmetric and possibly a little bigger than

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BELOW Making a glass fibre seat from scratch acted as a refresher course in pattern and mould making techniques prior to the big push on the T5’s bodywork

it need be. We knew someone who would sell us a seat for about £60 but it would not be designed for our car. So we decided to make our own. Making a glass fibre seat from scratch implies making a pattern (the plug), a mould and a product, nothing difficult, but all time-consuming. The real clincher was that it gave a chance to brush up on pattern and mould making techniques for when the time comes to get on with making the bodywork for real.

the car to make sure that it fitted in the gap and up to Rod’s body to make sure that it would fit him. The width of the seat was adjusted using the threaded bar. We both like a seat that gives solid support under the arm as well as at the hips.

Stage 2 was to panel in the seat by gluing sheets of MDF to provide the seat back and bottom. To give some structural strength, we did not rely only solely on the glue, but added some glass fibre reinforcement at the

It was not a good idea. It had all the required characteristics but also, unfortunately, extreme fragility. At the stage that the picture was taken, it had already suffered one breakage at the end and careless use of sandpaper gouged the surface.

This does not invalidate the technique, which can be used to make complex-shaped patterns by creating a stack of sheets and carving and sanding them to shape. This can then be consolidated by casing it in a thin skin of GRP which can be sanded and filled until a satisfactory surface is achieved. It is one of our intended processes for making the new bodywork. In this context though, the small amount that was being used was far too fragile.

Using foam requires careful choice of materials. The commonly available types are polystyrene (usually white, pink or blue) or polyurethane (which is usually a cream or brown colour but sometimes green). The polystyrene foam is dissolved by polyester resin systems but the polyurethane is immune. If you want to use polystyrene (as a core for a wing, for example) you will

We can move the fuel tank forward into what we had originally planned to be a part of the cockpit” When that is depends on when Oxford Brookes University students come up with the results of their final year projects that cover overall body shape and front and rear downforce. So if Juan, Melania and Robin are reading this, no pressure but your contribution is on the critical path!

The first step was to measure the cockpit space and create a profile of the proposed seat. Two profiles were cut from a sheet of 6 mm (quarter-inch) MDF and spaced apart using threaded bar. This was offered up to

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joins. This created a structure robust enough to take the driver’s weight so that we could check that the whole thing would be the right size. The Stage 2 photo shows the bonded seat and some polyurethane foam that was intended to provide a stiffening edge. The foam is the ideal material to provide the shape. It is cheap and readily available as cavity wall insulation. It is resistant to the polyester resin that we were using and easily formed with a saw and by sanding.

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PRACTICAL RACER 750FORMULA BUILD PROJECT PART 12

ABOVE Stage 2: back and bottom panels were bonded on for the second stage of the seat fitting BELOW The seat pattern after the body filler but before painting a double-skinned beam that will contribute greatly to driver safety. A side issue was that screwing the side panels to the wood had the effect of pulling them slightly outwards and increasing the draft on the pattern (the fact that the pattern tapers outwards towards the top is important when it comes

react with polyester resin. In particular, cellulose will cause havoc and a quick test with an acrylic-based car paint aerosol proved that it too was unusable.

The best stuff to use is any two-pack paint because it will chemically cure rather than dry by the evaporation of solvents. It’s the solvent that is the problem. If you do decide to use a two-pack paint you need to be very careful with personal safety. Buy a suitable respirator when you buy the paint and follow the safety warnings. We used a high build primer based on the modern 2k acrylic system, which is less toxic, but still needs careful handling. To minimise the risks the paint was mixed outdoors and applied by brush.

It was then taken into a heated workshop to speed the curing process. This left an awful lot of rubbing down, by hand to avoid accidentally cutting through to the MDF as might have happened if a machine was used. Since this is a seat, the final product needs to have a nice dull black finish, so I stopped at 400 grit. Next came the release coat, which in this case was four coats of wax applied at intervals of more than one hour. PVA release agent is pretty standard,

You will know when you are going too far with the polishing because you will reach the second coat of gel resin”

need to use epoxy resins. Polyurethane is unaffected by either system. Theoretically it is possible to coat polystyrene with a substrate so that the polyester resin does not come in contact, but it is difficult to do properly. Neither foam is sensitive to the reinforcing material – it cares not whether it is glass, Kevlar or carbon.

Because of the fragility of the pieces on the seat pattern, the foam was stripped off and replaced with a stout wooden frame. On the finished product, the shape that this imparts adds stiffness to the whole structure and if it is filled with foam it will be possible to create

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to releasing the product from its former).

The relatively open shape of the seat, the flat panels and the built-in draft angle all help with release, but the deep side beams make life more complicated. A way to envisage this is to form one hand into a fist and to grip the fist with the other hand. This is the equivalent of laying up a composite product on to a male mould. As it cures, the composite shrinks and grips more tightly, making the final release more difficult.

The next stage was to finish the pattern. All the sharp corners were radiused, the external ones sanded down and internal ones created with car body filler and sanding. All patterns need some sort of paint finish and care is needed here, both for yourself and for the work-piece. We are looking for a paint system that gives a good finish and is not reactive with the resins that we use. The obvious way to do it is by spraying, but many spray systems use a solvent that will

but we avoided it because we were slightly worried by small areas of porosity on the pattern and it does not work well in these circumstances. PVA undoubtedly does work, but you need to be absolutely sure that it has all dried off before applying the gel coat.

If there are any areas on the pattern (such as small cracks or poor surfaces) that you are unsure about, you can use children’s modelling clay (UK trade name Plasticene, not Play-doh) rolled into a small stick, dipped in wax and used like a lipstick to fill small imperfections.

One thing to bear in mind when making any pattern is that the finish has to be as good as you want for the finished product.

If you want to create a shiny gel coat finish, you need a shiny polished pattern. The only exception to this rule is that the product will be the third generation of your shape. So if there are scratches in the pattern, these can be polished out when the mould is

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Faxback this form on +44 (0) 208 446 2191 Racecar Graphic are leading publishers of motor racing books and periodicals, and organisers of specialist workshops for the industry. Racecar Graphic publish the monthly Race Tech magazine.

For further information please contact Racecar Graphic Limited e-mail: info@racetechmag.com 841 High Road, London, N12 8PT, UK, Tel +44 (0) 208 446 2100 Fax +44 (0) 208 446 2191 E-mail: info@racetechmag.com. Website: www.racetechmag.com

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PRACTICAL RACER 750FORMULA BUILD PROJECT PART 12

manufactured. A very slight scratch in the pattern becomes a very small rib on a mould and therefore much easier to flatten on the mould than the pattern.

Some commercial outfits go as far as making their moulds with two gel coats.

remained. More resin was added and the second layer of mat applied with more stippling. A roller could have been used but it all adds to the clean up time later. For the mould, it is more important to get a solid laminate and the resin/glass ratio is not too

Don’t trim completely. Leave a few tabs in the laminate as handles to help you separate the parts” They use a colour for the first coat that is critical. When it came to making the final unlikely to be used as a product. Brown or product, we took more care with the muddy green is good. The second coat wetting out and tried hard to minimise the can be a contrast to the first. The mould resin used in order to keep the proportion of can then be polished after releasing it from glass as high as possible. Done carefully, a the pattern and you will know when you ratio of 2.5:1 resin to glass is possible. If we are going too far with the BELOW Deadlines prevented spending polishing because you will much time on polishing the mould, reach the second coat of seen here waiting for the gel coat gel resin. In case you were thinking that it would be a good idea to have a very thick gel coat and polish away to your heart’s content – the problem is that small air bubbles tend to form just under the surface and spoil the idea.

This is another good reason for the two gel coat approach.

We envisaged a very low production run for our mould so it did not need to be too special. Two gel coats were used to allow a bit of meat for polishing out the imperfections of the pattern. A proper production mould would be at least two or three times as thick as the product but in this case we settled for two had used cloth instead of mat, the ratio layers of 450gm/m2 chopped strand E-glass would be better still (2:1 or less) and if we mat reinforcement (that’s the normal commercial general purpose matting).

Although this results in a fairly lightweight mould, we paid a bit more attention to thickening the edges of the mould to at least make it feel more robust.

After the gel coats had been applied to the pattern and allowed to cure, lay-up resin was painted on and the first layer of glass added. This was fully wetted out by stippling with a brush until no air bubbles

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had chosen to use vacuum bagging techniques it could be improved still further.

The resin-rich approach to making the mould is likely to have been about 3:1. This gives a solid laminate but one which is lacking in ultimate strength.

Once the glass fibre has been laid up, the curing process of the resin can be used to our advantage. The product will be stiff enough to de-mould in one to two hours but this is not recommended because curing

will continue over the next 48 hours. But the good news is that after about 20 minutes to half an hour, the resin will have cured sufficiently to allow it to be trimmed with a sharp knife. The trade knows this as the ‘green’ stage. Don’t trim it completely, but leave a few tabs in the laminate as handles to help you separate the parts. This saves the hours of work that would be necessary with a saw if you wait until it is fully cured. So, sadly, when you have finished laminating and simply want to get yourself cleaned up, you need to hang around until you can do your green trimming. It’s a good opportunity to clear up the workshop!

Ten minutes of vigorous exercise separated the mould from the pattern (which did not survive the experience unscathed). The new mould was treated to another round of

rubbing down (DA sander with 320 grit pads), polishing with cutting compound and being given four more coats of wax. Then the whole gel coating, laminating, trimming and pulling began again in order to create the product. This time more attention was paid to the resin glass ratio – thin gel coat, a brush used to apply the resin in the first place and careful consolidation of resin and mat with a roller. The process ended with the removal of surplus resin with the brush.

So that’s it. We now have a seat and we are back on the plan. Cockpit systems next. RT

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The follow-up to Jan Zuijdijk’s original book that has been edited by William Kimberley, editor of RACE TECH magazine.

The author, who has been involved with suspension design and development for race and high-performance road cars for more than 40 years, writes about the evolution of suspension systems over the decades.

However, this is more than just an historical book but a very practical one that will help the driver and vehicle dynamics engineer set the car up in the best possible way.

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RED RACE EQUIPMENT DIGEST

Edited by Chris Pickering

STAR IN THE ASCENDANCE CD-ADAPCO has released a new version of its STAR-CCM+ multiphysics engineering simulation software. The latest iteration, v6.02, is intended to reduce the time and cost associated with product development. It features new simulation technologies and numerous improvements to existing simulation processes.

One such addition is a specific battery simulation module, which allows the simulation of flow, thermal and electrochemistry phenomena for Li-Ion battery cells and packs, allowing the user to simulate battery behaviour in a single environment. It includes user defined discretization controls for thermal and electrochemical network within a cell, as well as automated problem definition, designed to quickly create battery packs from defined cells.

Another new feature is the electro-deposition coating (ecoating) model, which simulates the deposition of paint under the influence of an electric field when a charged product is dipped. This means that, with the appropriate user-defined paint properties, body engineers can examine the efficiency of a painting process by predicting

exactly how the layers of paint accumulate over time.

What’s more the revisions also include changes to the software’s post-processing features. It now gives the option of histogram graph types used for statistical analysis (appropriate for Lagrangian analysis, cell quality visualization and so on), along with start and end markers for streamlines, iso-line values, log colour scales and uniformity index reports. RT

HRE PERFORMANCE WHEELS NEW FROM HRE Performance Wheels, the R40 Monoblok is a forged onepiece wheel designed specifically for motorsport use. It is constructed from 6061-T6 aerospace grade aluminum and is a direct descendant of the custom-built model used by Fall-Line Motorsports to win the 2010 GrandAm GS Championship. However, the new version is lighter, starting at just 17.5 lbs (7.9 kg), and now features a new mesh-style design.

The R40 range is engineered to German TÜV specifications in HRE’s own manufacturing facility in California. Finishes include Satin Black, Satin Silver and Brushed with Clearcoat, while the width options for the 18 inch diameter rims range from 8.5 to 12 inches. The wheels come in multi-lug and centre lock versions and the open dish shape is designed to be ‘rattlegun friendly’ to help with rapid tyre changes. RT

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RT

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NEW DIRECTIONS IN RACE CAR AERODYNAMICS Designing for Speed

By Joseph Katz Published by Bentley Publishers ÂŁ23.95

+ Post and Packing

Well versed in the subject of aerodynamics as the Department Chair, Aerospace Engineering and Engineering Mechanics at San Diego Univserity, Dr Joseph Katz does an excellent job of giving a layman's introduction to auto-aerodynamics.

order online @ www.racetechmag.com For further information please contact Racecar Graphic Limited e-mail: info@racetechmag.com 841 High Road, London, N12 8PT, UK, Tel +44 (0) 208 446 2100 Fax +44 (0) 208 446 2191 E-mail: info@racetechmag.com. Website: www.racetechmag.com

RACE TECH

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RED RACE EQUIPMENT DIGEST

LONGACRE RACING PRODUCTS LONGACRE RACING Products has released a pair of new products, beginning with the Mini Chassis Height Checker. Not to be confused with the diminutive British hatchback, the ‘Mini’ part actually refers to the fact it is a shortened and simplified version of the firm’s Chassis Height Checker, aimed at the club racer. Perhaps not surprisingly its purpose is to measure ride heights and it does so using a device not unlike a right angle tape measure; simply

slide the gauge under the car and raise the tape with the billet knob until you reach the chassis and it returns readings accurate to 1/16th of an inch.

Next comes another piece of lateral thinking from the Washington company, known as the Toe Bar and designed to provide the simplest way of measuring toe in. Constructed from T6 aluminium, it’s designed to be operated by just one person as a more accurate alternative to scribe lines

and a tape measure. Much like the Height Checker, all you need to do is place it under the car and adjust the billet rod until it contacts the wheel or tyre. The Toe Bar measures to an accuracy of within 1/16th of an inch and can be used for vehicles of up to 88” track. RT

THE SILICON SENSE

FOR SOME years now race and rally teams have been including electronic gyroscopes in their data acquisition armoury. These little sensors are often required to provide extremely accurate readings in very harsh environments, subject to constant vibration and extremes of temperature, so it comes as no surprise to see they’ve moved on somewhat from the basic spinning top.

The new Dynamics Measurement Unit DMU1 from Silicon Sensing, for example, features a sixdegrees-of-freedom inertial measurement unit comprising gyros and accelerometers, which enables full 3-D motion sensing. It uses an on-board 16-bit processor to collate the sensor data, carry out temperature compensation (based on individual device calibration by Silicon Sensing) and send the

data to a host computer via a CAN bus interface. The end result is an angular rate measurement range of ±250 degrees per second and a linear acceleration measurement range of ±8g.

The company claims the DMU1’s robust construction makes it particularly durable, allowing it to withstand the force of stone strikes when mounted externally. It also points out that micro electro mechanical (or MEMS) architecture at the heart of the sensor is inherently robust, with warranty returns totalling less than 1 part per million.

Already widely used by mainstream automotive manufacturers, the DMU1 has recently caught the eye of race teams, such as Newman/Haas Racing, which uses the product on its IRL cars. "We've tried most data collection systems available and Silicon Sensing's DMU01 has continued to impress us,” commented Newman/Haas data engineer Bruno Couprie. “The unit has been reliable, the data has been accurate and, best of all, the information has been completely consistent and repeatable in challenging conditions.” RT

WINDS OF CHANGE WINDFORM XT 2.0 from CRP Technology is a carbon-filled polyamide-based material used in Selective Laser Sintering. An evolution of the original Windform XT, its mechanical features make it particular suitable for high performance applications in motorsport, aerospace, and defence.

Windform XT 2.0 retains the matte black colour of its predecessor, but features improved mechanical properties that include an 8 per cent increase in tensile strength, a 22 per cent in tensile modulus and a 46 per cent increase in ultimate elongation. Although primarily intended for rapid prototyping, it can also be used for functional parts in some instances. Typical applications include intake manifolds, coolant pipes and air ducts. RT

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RED RACE EQUIPMENT DIGEST

DAVIES, CRAIG COOLING SPECIALIST Davies, Craig has released a new lightweight version of its EWP 115 water pump. So named because of its flow rate of 115 litres (or 30 US gallons) per minute, the electrically-driven design is designed to be used with the firm's EWP/Fan Digital Controller and is claimed to enable more precise control of engine temperature than mechanical its equivalents, as well as significantly reducing parasitic losses. What's more the fact the pump can continue to circulate coolant after the engine has stopped makes it possible to all-but eliminate heat soak problems.

The launch of the EWP 115 also marks a renewed focus on international sales for the Australian brand, which has recently appointed Philadelphia-based Turn 14 Distribution as a US distributor. Speaking on the announcement, Davies, Craig's sales and marketing manager commented: "The launching of the new alloy EWP115 Electric Water Pump and variable speed EWP/Fan Controller will compliment our other EWP models in the automotive

aftermarket sector and we are very excited at the prospects this new product will offer us globally ... There’s no doubt the

appointment of Turn 14 will allow this great Australian cooling product to reach millions of potential customers in the US."

THOR RACING BELT DELETE OPTIONS FOR 1UZ-FE ENGINES THE ROVER V8 was once the default choice for low volume car manufacturers and home constructors in the UK. TVR, Marcos and Ginetta are just a handful of the marques that have taken to the track

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with the ubiquitous Buick-derived lump, but these days it’s becoming somewhat long in the tooth. As a result an increasing number of car builders are looking to the torquey Lexus 1UZ-FE V8 as a modern

equivalent. Many, however, no longer need the auxiliary pulleys that once powered things like air conditioning compressors and power steering pumps, which is where Coventry-based THOR Racing steps in.

Its new Belt Delete kit allows the selective deletion of extraneous pulleys and components to reduce belt friction and weight. The basic package contains two replacement covers, which are available on an exchange basis for the original item. They’re designed to provide an aesthetically pleasing replacement for the factory idle tensioner and second idler, also allowing the A/C unit and PAS pump to be removed for competition and track applications if desired.

Customers can also opt for an anodised belt tensioner and idler replacement, which includes a much shorter belt to hugely reduce the unnecessary routing of the factory serpentine belt. Either way, the company claims a power rise of between 5 and 10 bhp thanks to the improved efficiency, as well as a weight saving of some 14 kg. RT

RT

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The science of flying on the ground Special Offer! 8 Issues for the price of 7 Bernoulli

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BERNOULLI is a quarterly journal that explores in unprecedented depth the theory and practice of road and race car aerodynamics. Its incisive content includes road and race car aero design and development studies and insights into wind tunnel design and operation, the use of CFD and on-track aero testing techniques.

Clearly, Bernoulli is essential reading for all involved in the operation of wind tunnels, wind tunnel developers and suppliers of rolling roads, instrumentation and flow visualisation technology. It is equally vital for model makers and testing service providers and for suppliers of CFD software and design and manufacturing software.

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Faxback this form on +44 (0) 208 446 2191 Racecar Graphic are leading publishers of motor racing books and periodicals, and organisers of specialist workshops for the industry. Racecar Graphic publish the monthly Race Tech magazine.

For further information please contact Racecar Graphic Limited e-mail: info@racetechmag.com 841 High Road, London, N12 8PT, UK, Tel +44 (0) 208 446 2100 Fax +44 (0) 208 446 2191 E-mail: info@racetechmag.com. Website: www.racetechmag.com

RACE TECH

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RED RACE EQUIPMENT DIGEST

HOLINGER SF GEARBOX HOLINGER ENGINEERING has unveiled a new sequential gearbox for front wheel drive competition cars, known as the SF. It's rated at up to 365 Nm (270 lb ft) for endurance racing events and weighs just 35 kg (77 lbs).

Inside the T6 heat-treated alunminium case sit six indirect forward gears, a reverse gear and a final drive, all of which are profile ground for increased efficiency and durability. There's an extensive range of

different ratios for each and a gear position sensor is supplied for either an ECU input or a standalone gear indicator.

The SF features a pressure-fed lubrication system with the provision for an external oil cooler. It consists of a pump, a magnetic paper element filter and a spray bar to feed cooled oil directly onto the gears. Through-shaft lubrication carries the oil on to the needle roller bearings and a

EIBACH UNVEILS NEW ERS SET UP CENTRES SINCE ITS inception in 1986, the ERS range of competition springs from Eibach has taken teams to the podium in virtually every genre of motorsport, including Formula One, NASCAR, touring cars and the World Rally Championship. Now the German firm has unveiled plans for a network of individually chosen motorsport specialists to assist in the supply and set-up of ERS products in the UK. “Each dealer will be a highly-trained and experienced motorsport outfit, specialising in a certain genre of competition. Able not only to supply the correct parts from the vast ERS portfolio, but more importantly, advise on choice and set-up to the driver, engineer or team looking to gain a true competitive advantage,” commented Eibach UK’s general manager, Greg Kirby.

“End-users will be able to call Eibach UK, outline their requirements and be directed through to the appropriate specialist centre to speak to an expert in their area of competition.”

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Eibach can supply anything from a multicar batch to a single spring, and the extensive range provides a huge choice of rates. As well as main springs, tender springs and helper springs are also available. This gives the option of running two or even three springs in series – quite literally stacked on top of each other – giving a softer initial rate followed by a firmer rate for larger wheel movements. This helps the wheel to follow the small movements produced by the changing contours of the track, but then provides a stiffer rate to oppose body roll and dive/squat characteristics at larger deflections. RT

jet-feed supplies the differential.

The input comes via a removable quill shaft supplied custom built to requirements, while the output takes the form of either 86mm PCD bolt-up flanges, integral G169 or G182 tripods, or bespoke fittings. All gears and shafts are made from case-hardened nickel chrome steel and the selector forks are made from high tensile nitrided steel. RT

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