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


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.”


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.”


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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