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27 mars 2011 7 27 /03 /mars /2011 23:30

Formula 1 engineers obsess over light weight, but carbonfibre isn’t the only weight-saving trick under the MP4-12C’s skin, as Steve Cropley discovers.

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On one of the new McLaren supercar’s lightest on most important components, a cross-car beam cast in magnesium alloy that supports the dashboard and steering column, there’s a small McLaren emblem, spark-engraved into the metal.

When a car is fully built, its owner will never see it, but chief engineer Neil Patterson points it out on a half-cut chassis. “See that?” he says. “It saves 2.4 grams. That might not sound a lot, but it’s an important symbol. It reminds us every day how important it is to save weight in this car.”

Patterson claims the whole car has been built using what engineers call the Five Per Cent Rule. “You sign a part off,” he says, “and then you find another five per cent weight saving. In a whole car, it really adds up.

Such passion and attention in details is evident in every part of McLaren’s new MP4-12C. You get the flavour of it from any of the 300 people who have worked for four years to bring it to life – but none more so than Anthony Sheriff, McLaren Automotive’s managing director.

No one knows better than Sheriff that there is already an impressive selection of £160,000 mid-engined sports cars on the market. An inveterate sports car buyer and former senior executive with the group that controls Ferrari, Sheriff knows McLaren faces a tough battle to create market space for space for its forthcoming range of up to four mid-engined models, the first of which is the 12C. /…/

“Being as good as the others isn’t the answer,” says Sheriff. “We’ve designed everything to be the best. There are no carry-over components in the MP4-12C. They just wouldn’t be good enough.”

Such determination is admirable, but one question still burns: how do you go about beating Porsche and Ferrari at their own game? Sheriff says it starts with a refusal to accept compromise. “I call the 12C our ‘and’ car,’ he says. “Compared with its rivals it is stronger and lighter. It’s small outside and spacious inside. It has better handling and is more comfortable. One advantage doesn’t affect another. Above all, the 12C has more performance and better fuel efficiency; with nearly 600 horsepower on tap it’s the most powerful car in its class, yet its CO2 output of just 279g/km means every horsepower is produced more efficiently than virtually any car on sale – petrol, diesel or hybrid.”

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Structural layout

Width is a key difference between the MP4-12C and its rivals, according to managing director Antony Sheriff. Both the 12C’s body and its front and rear tracks are 25mm narrower than those of the Ferrari 458 Italia, reflecting Sheriff’s belief that controlling overall width makes a supercar more capable on the road.

The 12C is remarkably close in most major other dimensions to the 458, whose engineering brings together knowledge Ferrari has amassed in building mid-engined V8s in the 40-odd years since the Dino. But the McLaren has advantages in power (5.2 per cent) and torque (11.1 per cent). And its 20mm longer wheelbase (for 18mm less overall length) reflects the unusual roominess of its cabin, accessible through what McLaren calls dihedral doors.

McLaren’s official dry weight of 1338k appears to make it 50-100kg lighter overall than the Ferrari, an advantage due mainly to the weight-saving benefits of its central carbonfibre tub. /…/

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Chassis, suspension

Carbon also delivers important packaging advantages. McLaren engineers were determined that the 12C should have an uncompromised driving position and class-beating visibility.

“In aluminium chassis-frame cars, the need for a bulky structure behind the wheel arches is likely to push the pedal box inwards,” says chief engineer Neil Patterson, “while a bulky heating/ventilation system, usually from another production car, pushes the seats and steering column outwards. The result is a severely compromised driving position. The 12C’s compact carbon wheel arch structure and its specially built ventilation system allow the pedal box, steering wheel and seat to be perfectly aligned.”

Suspension is by double wishbones and coil springs front and rear, which sounds conventional. But the McLaren is unique in using an electronically controlled, interactive damping system – McLaren calls it Proactive – which provides the strong anti-roll, anti-dive and anti-squat qualities a 200mph supercar needs, while permitting supple bump absorption when appropriate. /…/

The dampers are hydraulically interconnected front to rear, and also from side to side. Through a system of sensors the car detects squat, dive, roll or warp (a kind of diagonal corkscrewing motion) as they happen and instantly configures the car to cope. Pressure (generated by the power steering pump when the car is travelling in a straight line and therefore doesn’t need steering assistance) is retained in Citroën-style high-pressure gas spheres and then fed to the appropriate corner(s) to tame any undesirable movements. Engineers say the car is extremely stable but its ride comfort is “out of this world.”

Engine, transmission

Powertrain chief Richard Farquhar says the idea of giving the new McLaren a comparatively small and light twin-turbocharged V8 is as fundamental to its make-up as the carbonfibre tub. In the earliest days a large, normally aspirated AMG-derived engine was briefly considered, but when Mercedes and McLaren decided to go their own ways – after which today’s MP4-12C concept was framed – it became obvious that a lighter, more compact turbocharged engine made a more modern and efficient solution. A bespoke 3.8-litre twin-turbo V8 was designed at McLaren, and a deal struck with Ricardo, the British-based technology company, to develop and build it for production.

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“Once we had laid out the car’s major dimensions, we knew no production-based engine would have worked in the space available,” says Farquhar. “The choice of a V8 was easy; it came from our race heritage. A V10 would have been longer. The 3.8-litre capacity gave a big enough bore size for good low-end torque, but was small enough to be compact and efficient.”

Installed in the car, the engine looks tiny, and very low because of its dry-sump lubrication system and flat-crank configuration. It is a four-valve-per-cylinder design with two chain-driven overhead camshafts per bank. The whole thing weighs just 150kg and it uses a compact mounting system that allows it to sit close to the bulkhead (“We save 30mm of wheelbase that way,” says Farquhar).

The ancillaries are driven by shafts running low along the sides of the engine, and the V8’s valley is well utilised, too; the oil/water heat exchanger is in there, plus an oil filter and a vacuum reservoir. The V8 is fuelled by port injection; Farquar says direct injection simply isn’t needed for the engine to achieve its objectives: 600ps (592bhp at 7000rpm) and 600Nm of torque (443lb ft between 3000 and 6500rpm). He agrees, however, that direct injection “provides us with a future opportunity”. In all, there are 34 ECUs on board.  

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The exhaust system, usually heavy and bulky in normally aspirated supercars, is remarkably compact. It consists of a small ‘log’ manifold on each side in cast stainless steel, connecting to a small, close-coupled catalyst, with another catalyst a little further along. The two main pipes connect in a ‘mixing box’, just inside the rear body, and feed two high-mounted outlets. An even lighter sports version is available, made from a nickel chromium-based alloy used in Formula 1 systems. Occupants hear the engine via a tuned sound generator in the inlet system that directs and varies sound into the cabin according to the chosen engine/transmission mode. The car can be muted while cruising, but highly vocal when used in anger.

The gearbox is a seven-speed twin-clutch unit with Graziano internals and a McLaren casing. It is specially designed to take advantages of the engine’s position in the chassis and deliver an unusually low centre of gravity for the entire powertrain. The driver actuates gearshifts via a race-style paddle system, which rocks on a central fulcrum and allows one-handed gearchanging up or down, a carry-over from McLaren’s F1 cars.

Another F1 tweak is Brake Steer, which forms part of the 12C’s chassis stability system to tame understeer and control wheelspin. In the 12C this is actually more sophisticated than the original F1 system, which used a second brake pedal and was banned when rivals complained. McLaren says Brake Steer has the same effect as a torque-vectoring diff but saves around 20kg.

There are two other important driver aids. By putting a gentle initial pressure on a gearchange paddle, a driver can activate a ‘pre-cog’ function that pre-loads the clutch, ready for a quicker gearchange. There is also a handy restorative function: if the driver brakes hard and forgets to change down, he can pull and hold the left paddle to summon assistance. When he accelerates away, the car is in the right gear, and at the right revs. Naturally the 12C also has the Automatic, Winter and Launch Control modes one finds in rivals.

Aerodynamics

McLaren’s aero expert, Simon Lacey, says the MP4-12C’s major styling features matched its aerodynamic goals well from the project’s beginning. Even the car’s ‘waisted’ shape helps present the main engine intakes to undisturbed air. Lacey cites four main development areas: the front cooling ducts, the radiator side intakes, brake cooling, and the core task of increasing downforce and decreasing drag.

Detail work has included tuning airflow into and out of the wheel arches, and making sure all intakes are fed and all outlets exhaust. The car has “a nice flat bottom” and an effective diffuser, says Lacey, and can develop 100kg of downforce at 150mph, spread over the car in proportion to its static weight distribution (43 per cent front, 57 per cent rear).

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Detailed aero development has brought important results. An afternoon spent with plasticine, reshaping the exterior mirror supports, brought a wind noise reduction “anyone would notice”. Another afternoon spent changing the shape of the windscreen wiper arm achieved the same thing. McLaren isn’t keen to divulge an overall drag factor for the 12C, but claims good results. “We reckoned the car to be draggier,” says Lacey, “but it’s spot on the original targets.”

The 12C’s headline aero feature is its air brake, a neat flap on the rear deck that deploys rapidly under heavy braking. Shaped like an upside down aeroplane wing, it rises to 57 degrees but is cleverly designed so that airflow acting on its base actually helps it erect itself, saving nearly 50 percent in the weight of the mechanism. The wing also helps to counteract the heavy nosedive that comes with rapid stops, keeping the car stable and allowing the rear wheels to accept more brake effort. “It’s a great system,” says Lacey – “a no-brainer in a car like this.”

Wheels, tyres

Programme director Mark Vinnels has a simple recipe for success: “There’s no substitute for miles behind the wheel.” Mindful of the ride deficiencies ultra-low-profile tyres often bring to cars like this, McLaren specifies 19-inch front wheels for the 12C, “to ensure the sidewall height is large enough for good impact isolation”. The car will wear specially made Pirelli P Zeros that use a softer compound than usual because the Proactive damper system exerts better control than conventionally suspended models. The rear wheels are 20-inchers, wearing mighty 305/35s.

Article published in Autocar special edition dedicated to the MP4-12C

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26 mars 2011 6 26 /03 /mars /2011 21:00

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McLaren chief designer Frank Stephenson has a world-class CV, but nothing prepared him for the challenges of a clean-sheet supercar. He gives Hilton Holloway a guided tour.

Frank Stephenson is a famously prolific designer; he’s worked on projects as diverse and iconic as the BMW Mini, Fiat 500 and the Maserati MC12. And he’s about to explain the thinking behind the first in a future family of McLaren supercars, to be designed and built at McLaren’s Woking base.

But unlike his previous projects, this brand has virtually no backstory, which offers both an unusual freedom as well as the difficulty of starting from a clean sheet. Having said that, virtually the first question that occurs to the enthusiast when looking at the MP4-12C is why doesn’t it look more like – or at least make more visual references to – the legendary McLaren F1 from 20 years ago, if not the original 1960s McLaren M6GT?

“It does make reference to the original,” says Stephenson. “It has McLaren’s strength in engineering and materials in spades. But it has to compete in its market segment – in the £160k-£170k-plus price range. It’s not the ultimate supercar. Of course we could do a car like that; we’ve done it before. But if we’re going to build a car company, we need to be in the segment that generates the biggest sales.

“The last thing you want to do is be restricted. If you are styling a Ferrari or Lamborghini, there’s a DNA that you have to follow. Everything you do [as a designer] has to have the feeling of the company. What we’re doing at McLaren is a chance to start with a clean sheet of paper. We’re starting a whole new design language for McLaren. I’m not saying the F1 wasn’t a fantastic car, but we know there are ways of doing things better – aerodynamics and packaging – than we did in the 1990s.

“You have to establish something that really hits you as containing the design cues from the new-age McLaren. But this is only the first product. Everything we do after this has to build up from this car.

When Stephenson worked on the Maserati MC12, many aspects of the shape were determined by the Ferrari Enzo tub and mechanicals beneath. What, then, drove the styling of the MP4-12C?

“This is pretty much the shape that could be developed around the engineering package. The whole car started from the inside out. Many people claim that’s how they approach a new car, but it’s really how we did it.”

So why not just let the engineers put a skin on the package and really go for form driven by engineering function?

“That’s pretty much what we did,” says Stephenson. “We took as much body mass as we could out of the car. That’s the McLaren way to do it. You don’t want sensual surfaces like a Ferrari or origami shapes as on a Lamborghini. When you consciously style a car, it always ends up larger than it needs to be. Ferrari get a nice shaped hip [over the rear wheel], but in a strict engineering sense it doesn’t add anything to the car. It just adds weight and material, and there really is an obsession with cutting weight at McLaren.”

Such is the priority given by McLaren to aerodynamic performance, Stephenson explains, that his design team had to follow the lead of aerodynamic calculations; the aero work was done under the aegis of Simon Lacey, who has worked on several McLaren’s race cars.

“The MP4-12C was done the same way as the Maserati MC12, in and out of the wind tunnel and using computational fluid dynamics. We’d take a shape, put it in the tunnel and then change it. We use a 30 per cent scale model, which offers a minimal difference to using a full-size car. We’d take information straight from the wind tunnel to mill out new clay models.

“The priority is to get the air to stick to the surface of the car. So we can throw special paint onto the car in the tunnel and then can see where streaks [of paint] are detaching from the surface. From there we can tweak the section of bodywork in question.

“I believe that form really is equal to function and that if it looks right, it is right. I don’t want a car the looks tortured, something that’s trying to fight against logic, because it just won’t work [visually].”

With aerodynamics driving much of the design process, Stephenson’s team took great care to finesse the MP4’s aero-honed surfaces for maximum aesthetic appeal. “Once a surface has been optimised, we in the design team can then negotiate on the surface highlights, which also means going backwards and forwards to the wind tunnel,” he says. “We need a full-size clay model at this point. There’s no way that you can judge surface highlights on a screen. We need to see the highlights and feel surfaces. We need to look at it from a million viewpoints. Ultimately, of course, it has to look good.”

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Air intakes

The majority of the car’s shape and detailing backs up this detailed account of its development – apart from the huge air intakes on each side. At first glance these look like pure styling. “A great deal of this car is about getting the air back to the air brake and into the side-mounted radiators,” he says. Most other manufacturers will angle the side radiators to get the maximum amount of air into them, but that’s counter to keeping the car as small as possible. We’ve mounted the radiators completely flat, parallel to the side of the car, so then you have the problem of getting the air into them.

“So when people look at this detail and say, ‘Why did you do such a funny panel for the air intake?’ it’s not styling, it’s pure engineering. This piece was designed on computer for maximum efficiency in turning the air inwards. If you moved the central blade outwards by a millimetre it would make a huge difference to the amount of air being channelled inwards. This is F1 technology.”

Stephenson gets down on his knees and feels the edges of the side air intake. He says he would, for example, have liked to thicken the leading edge of the MP4’s air intake, but even such tiny changes were overruled by aerodynamic considerations. And of course, once you’ve got the optimal amount of air into the 592bhp engine and its surrounding bay, you need to get it out again.

“The whole rear end is not exactly like a Swiss cheese, but there’s a lot of openings, such as the tailgate being lifted on the rear. Too many openings are not good for aerodynamics, but when you do get the heat from the engine building, you need heat evacuation areas, particularly at the back because there’s a lot of heat from the exhausts when the car is idling. The engineers gave me the amount of extraction area we needed in centimetres squared, but how that was divided up was down to us. We [the designers] had a pretty free hand.”

Although it is hard to tell when viewing the MP4-12C in isolation, the car is significantly smaller than its direct rivals.

“It was critical to get the cowl area as low as we possibly could,” says Stephenson, “so we designed the HVAC [heating and ventilation system] from scratch so that it is extremely low compared with the competition. The result is that when sitting in the car the highest point of the body from the driver’s point of view will be on the fender, right over the centre of the front wheel. It’s a reference point to give you a permanent sense of the position of the front wheels.”

Stephenson also points out the steeply sloping windscreen and the ‘cab-forward proportion’. “It’s an ideal position for driving a car like this; you feel pushed to the front.

“You might imagine the car will have a very small boot, but it’s probably got the best luggage space in the segment. The size of the space in the nose was a sacrosanct area during development.”

Although the MP4-12C’s chassis is a work of art in carbonfibre and aluminium, it is actually mostly skinned in Sheet Moulded Compound (SMC), a kind of high-end plastic.

“For pedestrian impact reasons, three sections – the bonnet, the fender and the roof – of the skin are made in easily deformed alloy. Elsewhere we’ve used SMC. It’s not cheap, but it is the right material. Using carbonfibre panels for the outside skin would have been lighter, but it probably wouldn’t be the best material for crash performance and it takes a lot of time and effort to paint it.”

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Bespoke cockpit

Lift the 12C’s door (there’s no handle, just a touch-sensitive pad) and it reveals a sober, thoughtful cabin. The only unexpected design flourish is three protruding air vents.

“We wanted to make an interior that offered the least distraction possible,” says Stephenson. “So it’s i-Pod-ish in that you don’t see that many buttons and we’ve kept the buttons off the steering wheel. It’s as simple as we could make the interior.

“If you need it, it’s on the touch-sensitive screen. The way of adjusting the main functions – chassis and engine settings – is similar to the manettino dials used by Ferrari. The controls you only use when you’ve stopped – the hazards, reverse selection and handbrake – are in the centre console because you can take your eyes off the road to use them. We made the car as narrow as possible and even the GPS screen is in portrait mode to save space. But it means that the driver is much closer to the middle of the car, which is a great help for the weight distribution and therefore a benefit for the handling.

“Everything in the interior is bespoke and even the column stalks are drilled for lightness. It’s lightweight but solid feeling. The steering wheel rim is shaped off Lewis Hamilton’s gloved hand, but slimmed down by a couple of millimetres. The gear changing paddles are mounted on a single beam, so pulling one paddle inwards makes the other paddle move out.”

It wasn’t McLaren’s intention, Stephenson concludes, to make the 12C look ‘modern’. “We wanted to make this car look effective and purposeful, like a military aircraft. If you get it right, there’s no reason for the car to change through its life cycle. We followed a good, honest design direction. It’s a look that will be in today and gone tomorrow.

Article published in Autocar special edition dedicated to the MP4-12C

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24 mars 2011 4 24 /03 /mars /2011 20:00

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Presiding over a successful F1 team was never quite enough for Ron Dennis. In fact, he’s wanted to start a car company for as long as he can remember, he tells Steve Cropley.

Ron Dennis has wanted to be the boss of a car company fir so long that he’s forgotten exactly when the idea first took shape in his mind. Certainly it was during his earliest motor racing days, when he was still a race mechanic for drivers that included Jochen Rindt and Jack Brabham, and well before he began the meteoric rise through racing’s hierarchy that has established him as Britain’s foremost motorsport team-builder.

“if I were writing my own epitaph,” he says, “I’d like to be remembered as a successful entrepreneur across a variety of disciplines, not just a racing man. Winning grands prix is extremely hard, but understanding the basic concept isn’t so difficult. But creating a successful, well rounded automotive group has many more challenges, and that’s what attracts me now.”

Dennis and McLaren have had two previous brushes with car manufacturing, both combining success and failure. The 1993 McLaren F1 (which we declared “the finest driving machine yet built for the public road”) remains an automotive icon but achieved only a third of the planned 300 units, and only reached financial success when adapted for racing and winning Le Mans in 1995.

The 2003 Mercedes-McLaren SLR(or Mercedes-Benz SLRMcLaren, to give the official title) was made by McLaren in Woking, launched at just under £300,000 and produced until 2009. Around 1200 were built, but even this fell below the 500 a year Mercedes wanted, and the car became a symbol of the differences between two proud partners. A mid-engined, Merc-powered proposal called P8 was briefly contemplated, but it was overtaken by the P11 concept, which has turned into the MP4-12C, powered by McLaren’s own components and the first product of the newly independent McLaren Automotive company.

Dennis, used to keeping secrets all his life, lets little slip about the scale and future products of the car business. What has emerged so far, through casual conversations and cracks in the walls, is that “up to four” models are planned, all mid-engined, all two-seaters, all using the ‘Monocell’ carbonfibre central tub (of which Dennis is inordinately proud) and including at least one open-top model. Loose-lipped suppliers have been led to believe first-year 12C sales should be about 1000 cars, but you won’t hear Dennis saying very much of this, although he does allow that McLaren Automotive sees the 12C as “the core segment” in the models it intends to offer.

“Two-plus-twos and four-doors are certainly not in our plan,” he says, “but we’d be stupid to have a mindset that says we’re not going to do them for all time. Porsche’s move into SUVs has been very, very successful. You’ve got to admire them for it. But we’re an embryonic company. The worst thing we could do is to stray off piste. Our task now is to get the quality right, and mature as a company.

“What I can reveal is that our new McLaren Production Centre,” he gestures at a vast but orderly building site almost out a sight across the lake from the McLaren Technology Centre,” is configured for three shifts at an annual rate of 2000 cars a shift. However, we don’t ever expect to go over two shifts – which means our maximum capacity will be 4000 cars a year.”

The interviewer falls immediately on these numbers; surely they mean McLaren will always be more exclusive than Ferrari and much, much more exclusive than Porsche? This may be true, but Dennis fails to claim such a cheap advantage. The game, he knows, is bigger than this.

“It’s not a question of being exclusive,” he says. “That’s simply the number that fits our business plan. And we’d be foolish to say nothing in that plan would change up or down. For now, our major preoccupation has to be with quality.”

Intriguingly, Dennis says he doesn’t view Ferrari as a key competitor, despite the fact that his car is close in many of its dimensions to the new 458 Italia, and managing director Antony Sheriff will readily admit that much of the car’s benchmarking has been against it. “We have a very healthy respect for Ferrari,” says Dennis, “but I don’t see them as our prime competitor. People will compare the performance, styling and driving capabilities, but I can tell you that our prime targets are owners of other brands. How many will come to us from Ferrari? I’d say it will be a low percentage. I’m more sure that many of our owners will have both.”

It will strike you, if you’ve interviewed car industry bosses before, that Dennis – known as w racing man – sounds remarkably like someone steeped in car industry experience. Has he spent time in other people’s factories, boning up for the new tasks? “Of course I have,” he says, “but you’ve got to remember we have some experience gathered during the F1 and SLRphases. And through racing I’ve had contact with Honda, Porsche, Ford, Peugeot and Mercedes-Benz. If your ambition is to have a car company, you don’t walk around these places with blinkers on.”

Even so, building the 12C without the muscle and scale of an automotive giant has involved a steep learning curve, Dennis admits. “One of my biggest ambitions is to build a perfect supplier network,” he says. “Suppliers absolutely control your destiny. If they do sub-standard work, and you don’t catch it, you’re in for a never-ending headache. Building the network we need, with the required level of commitment, trust and quality, has been very, very challenging.”

Given his passion for detail, Dennis has surely spent many miles chasing details from the driving seats of prototypes – hasn’t he?

“My answer to that,” he says, “is two words: Vince Higgins. Vince was a race mechanic way back in the ‘60s. He worked for McLaren when I was at Brabham.

“We were at Watkins Glen, and in those days it was normal for mechanics to drive cars from the tech centre to the grid, quite a long way. Vince was driving a McLaren when someone stepped in front of him. He swerved and took the back wheel off on a post. From that day I decided there was no case for anyone to drive race cars other than the professionals, and that’s how we work here.

“We have professional engineers whose job is to get the MP4-12C absolutely right, and they need the freedom to do their jobs as well as they can. I did drive some prototypes in Spainwith the other shareholders a year ago, and I’ll make sure I’m up to speed before the car goes on sale. But if I kept jumping in and out it would be too unscientific, too distracting. I’ll do it when the time is right.”

Article published in Autocar special edition dedicated to the MP4-12C
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14 mars 2011 1 14 /03 /mars /2011 07:30

McLaren_PP_Portimao_56.jpgInteresting piece of information found in Evo:

There's a tiny, front-facing camera in the roof lining of the orange test car. At first I thought Ron was spying on us. Turns out it's a system called Track Data Display. There are two other cameras, one forward-, the other rear-facing. When finished, the package will allow owners to match data from the car to video footage of themselves driving. Yes, there are already dozens of systems like this available, but this one doesn't involve miles of cable. Nor do they offer the chance to match yourself against Lewis or Jenson - there’s talk of having the drivers record laps so that owners can overlay their data traces with someone wearing Vodafone overalls.
If that isn't cool enough, the possibilities with ProActive Chassis Control and good old GPS are mouth-watering. Test driver Chris Goodwin explains: 'Just imagine if we went to every major circuit and recorded a definitive set-up for the suspension on each corner, and an owner could just select the circuit on the car's computer to have optimum chassis settings for that location.'
Further proof that McLaren is approaching the supercar like no one has before.

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10 mars 2011 4 10 /03 /mars /2011 07:00

ML000015_1_2.jpgDesign talks has published two articles with McLaren designer Frank Stephenson. The first one about the overal design of the car, the second one about interior design.

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9 mars 2011 3 09 /03 /mars /2011 23:00

A very interesting article about the monocoque chassis has been published a little while ago in Composite World. Link to the online article here.

0910 HPC FOD1

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4 mars 2011 5 04 /03 /mars /2011 20:00

Le site suisse Asphalte a publié récemment une présentation technique très complète et détaillée en français. J'invite donc tous ceux que le langue de Shakespeare rebute à se diriger vers ce lien!

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3 mars 2011 4 03 /03 /mars /2011 23:00

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Weight is the enemy of performance in every area of car design. It affects acceleration, speed, handling, fuel consumption and CO2 emissions – everything. McLaren Automotive engineers pursued weight saving obsessively. For example:
- The Carbon MonoCell not only reduces the weight of the structure but also allows for the use of much lighter weight body panels.
- The close position of the driver and passenger allows a narrower, lighter body while giving improved visibility with a clearer perception of the car’s extremities.
- Brakes with forged aluminium hubs save 8 kg and weigh less than optional carbon ceramic brakes.
- Lightweight exhaust pipes exit straight out the rear of the car, minimizing their length and weight.
- Airflow-assisted Airbrake deployment dramatically reduces weight of the Airbrake activation system.
- Small, compact downsized engine coupled to lightweight compact SSG minimizes vehicle length, weight and polar moment of inertia.
- Significant weight was pared off the alloy wheels through intensive Finite Element Analysis of wall thicknesses.
- The engine cooling radiators were mounted at the rear, as close to the engine as possible, to minimize the pipework, the fluids contained within them, and therefore weight. They were also mounted in car line to minimize vehicle width.

Source: Official press release - Sept. 9th 2009.

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3 mars 2011 4 03 /03 /mars /2011 22:30

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Le poids est l'ennemi de la performance dans tous les domaines du design automobile. Il handicape l'accélération, la vitesse, le comportement routier, la consommation de carburant et les émissions de CO2 - en un mot, tout! Les ingénieurs de McLaren ont entrepris une chasse au poids, avec comme principales mesures:
- Une monocoque en carbone, qui non seulement réduit le poids de la structure, mais permet également l'utilisation de panneaux de carrosserie beaucoup plus légers.
- Conducteur et passagers rapprochés, ce qui permet d'avoir une carrosserie plus étroite, améliorant la visibilité et la perception de la voiture.
- Des freins avec moyeux en aluminium forgé qui permettent d économiser 8 kg et pèsent moins que les freins en carbone céramique optionnels.
- Des tuyaux tuyaux d'échappement de sortie en ligne droite à l'arrière de la voiture, ce qui réduit leur longueur et le poids.
- Un Airbrake au déploiement assisté par le flux d'air (et non par un moteur), ce qui réduit son poids.
- Un moteur compact 'downsizé' couplée à une transmission à double embrayage elle aussi compacte et légère pour minimiser la longueur du véhicule, le poids et le moment d'inertie polaire.
- Une étude éléments finis fine de la structure des roues en alliage pour en réduire le poids.
- Les radiateurs de refroidissement ont été montés à l'arrière, aussi près que possible du moteur, afin de réduire au minimum la tuyauterie, les fluides contenus en leur sein, et donc le poids. Ils sont également montés de manière à réduire au minimum la largeur du véhicule.

Traduction / Source: Official press release - Sept. 9th 2009.

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