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McLaren F1 : châssis carbone, design aéro-dynamique, moteur BMW M Power V12. 627 ch.

McLaren F1 est la première automobile a permettre au pilote d’être en position centrale. Le 31 mars 1998, la McLaren F1 devient la voiture de série la plus rapide au monde avec une vitesse de pointe officielle de 386,7 km/h établie sur le terrain d’essais Volkswagen de Ehra-Lessien, en Allemagne. Ce titre a tenu jusqu’à l’arrivée de la Koenigsegg CCR de 800 ch en 2005, et de la Bugatti Veyron 16.4 de 1 200 ch quelques mois plus tard. Cependant, la McLaren F1 garde le record pour une automobile à moteur atmosphérique, et le moteur ne fait que 600 ch. La McLaren c’est l’automobile d’une génération. Ma génération c’est celle des années 1990. La génération qui a connu les premiers jeu vidéo Need for Speed. C’est sûrement là que toute une génération a découvert cette automobile fascinante. Mais ce qui est encore plus fascinant, c’est le parcours d’un entrepreneur, d’un engineer et d’un designer. Tous les trois et tous du team McLaren ont créé l’ultime road-car. Ever. Forever.

McLaren F1

Lire le post dédié aux début et parcours de Ron Dennis, Gordon Murray, Peter Stevens, et le projet McLaren F1
==> McLaren F1 : le projet ultime by McLaren Cars. Moteur BMW V12. L’héritage de la génération 90.

‘Power, pace and peerless quality, the legendary McLaren F1 is a technological masterpiece. The fastest production car of its time. The finest sports car of its generation. For many, the greatest supercar ever built.’

‘Brilliance takes time. It took four years to meticulously plan, design and build the all-conquering F1. Beautifully engineered and exceptionally quick, the F1 broke numerous world records during the ‘90s, and it remains the fastest naturally aspirated road car ever built. Only 106 cars were made in a limited production run, making the F1 one of the most exclusive cars in the world today.’

- McLaren Cars

Le châssis de la McLaren F1

Chief engineer Gordon Murray’s design concept was a common one among designers of high-performance cars: low weight and high power. This was achieved through use of high-tech and expensive materials such as carbon fibre, titanium, gold, magnesium and kevlar. The F1 was the first production car to use a carbon-fibre monocoque chassis.

McLaren F1 - blueprint

McLaren F1 – blueprint

‘After analysing existing supercar performance characteristics, the F1’s handpicked engineering team rethought every element of sports car design. Drawing on McLaren’s Formula 1 expertise, and with an uncompromising approach to design, they stripped weight, reduced drag and increased downforce. Every millimetre of the F1 was deliberated to create the world’s most exhilarating car.’ - McLaren Cars

Gordon Murray exploite de très nombreuses technologies et techniques utilisées en Formule 1. On ne change pas une technologie qui gagne.

Pour les matériaux, Murray ne se refuse rien : la coque sera intégralement réalisée en fibre de carbone, une technique alors encore jamais utilisée dans l’automobile. Ainsi, l’ensemble monocoque châssis-carrosserie est intégralement en composite. La structure se compose d’éléments moulés, soit sous forme mixe carbone-NIDA-carbone, soit en simples panneaux de fibres de carbone, unidirectionnelles ou tissées, selon les besoins.

La coque est encadrée par des solides longerons et des massifs caissons latéraux enveloppant les sièges des passagers. L’ensemble de cette structure est une véritable cellule de survie à la manière d’une coque de Formule 1 moderne.

The McLaren F1 was the first production road car to use a complete carbon fibre reinforced polymer (CFRP) monocoque chassis structure. Aluminium and magnesium were used for attachment points for the suspension system, inserted directly into the CFRP.

The engine produces high temperatures under full application and thus causes a high temperature variation in the engine bay from no operation to normal and full operation. CFRP becomes mechanically stressed over time from high heat transfer effects and thus the engine bay was not constructed from CFRP.

To enhance performance, handling, braking and sheer driving feel, the F1 team knew they would have to minimise weight – everywhere. Lighter and stronger than aluminium, the F1 was the first road car with a carbon fibre chassis. Its weight-saving wheels were made from magnesium alloy. The supporting sub-structure was made from titanium. Even the toolkit, made from titanium, was 50% lighter than a steel kit. - McLaren Cars

La direction à crémaillère passe dans un tunnel central en magnésium sur lequel se fixent les attaches des suspensions. L’habitacle est très particulier, avec 3 places de fronts, avec le conducteur au centre avancé vers l’avant, et les deux passagers de chaque côté en retrait. Cette disposition particulière des sièges permet aussi de réduire la largeur de la voiture.

The car features a central driving position – the driver’s seat is located in the middle, ahead of the fuel tank and ahead of the engine, with a passenger seat slightly behind and on each side.

McLaren F1 - blueprint engine

McLaren F1 – blueprint engine

Steve Randle, who was the car’s dynamicist, was appointed responsible for the design of the suspension system of the McLaren F1 machine.

It was decided that the ride should be comfortable yet performance-oriented, but not as stiff and low as that of a true track machine, as that would imply reduction in practical use and comfort as well as increasing noise and vibration, which would be a contradictory design choice in relation to the former set premise – the goal of creating the ultimate road car.

From inception, the design of the F1 vehicle had strong focus on centring the mass of the car as near the middle as possible by extensive manipulation of placement of, inter alia, the engine, fuel and driver, allowing for a low polar moment of inertia in yaw. The F1 has 42% of its weight at the front and 58% at the rear, this figure changes less than 1% with the fuel load.

The distance between the mass centroid of the car and the suspension roll centre were designed to be the same front and rear to avoid unwanted weight transfer effects. Computer controlled dynamic suspension were considered but not applied due to the inherent increase in weight, increased complexity and loss of predictability of the vehicle.

The suspension is a double wishbone system with an unusual design. Longitudinal wheel compliance is included without loss of wheel control, which allows the wheel to travel backwards when it hits a bump – increasing the comfort of the ride.

Castor angle wind-off at the front during braking is handled by McLaren’s proprietary Ground Plane Shear Centre – the wishbones on either side in the subframe are fixed in rigid plane bearings and connected to the body by four independent bushes which are 25 times more stiff radially than axially. This solution provides for a castor wind-off measured to 1.02 degrees per g of braking deceleration. Compare the Honda NSX at 2.91 degrees per g, the Porsche 928 S at 3.60 degrees per g and the Jaguar XJ6 at 4.30 degrees per g respectively. The difference in toe and camber values are also of very small under lateral force application. Inclined Shear Axis is used at the rear of the machine provides measurements of 0.04 degrees per g of change in toe-in under braking and 0.08 degrees per g of toe-out under traction.

When developing the suspension system the facility of electro-hydraulic kinematics and compliance at Anthony Best Dynamics was employed to measure the performance of the suspension on a Jaguar XJR16, a Porsche 928S and a Honda NSX to use as references.

McLaren F1 - sketch - suspension

McLaren F1 – sketch – suspension

McLaren F1 brakes by Brembo

The F1 features unassisted, vented and cross-drilled brake discs made by Brembo. Front size is 332 mm (13.1 in) and at the rear 305 mm (12.0 in).

The calipers are all four-pot, opposed piston types, and are made of aluminium. The rear brake calipers do not feature any handbrake functionality, however there is a mechanically actuated, fist-type caliper which is computer controlled and thus serves as a handbrake.

Gordon Murray attempted to utilise carbon brakes for the F1, but found the technology not mature enough at the time; with one of the major culprits being that of a proportional relationship between brake disc temperature and friction—i.e. stopping power—thus resulting in relatively poor brake performance without an initial warm-up of the brakes before use. (Since carbon brakes have a more simplified application envelope in pure racing environments, this allows for the racing edition of the machine, the F1 GTR, to feature ceramic carbon brakes.)

McLaren F1 tyres by Goodyear & Michelin

The McLaren F1 uses 235/45ZR17 front tyres and 315/45ZR17 rear tyres.

These are specially designed and developed solely for the McLaren F1 by Goodyear and Michelin. The tyres are mounted on 17-by-9-inch (430 mm × 230 mm) front, and 17-by-11.5-inch (430 mm × 290 mm) rear five-spoke cast magnesium wheels, coated with a protective paint and secured by magnesium retention pins.

Le design de la McLaren F1

McLaren F1 - design sketch by Peters Stevens

McLaren F1 – design sketch by Peters Stevens

McLaren F1 - designer Peter Stevens

McLaren F1 – designer Peter Stevens

‘The F1’s chief designer, Gordon Murray, had been working on a one-plus-two seating configuration since 1969. Twenty years later, his innovative arrowhead concept came to fruition in the F1.’

‘No spoilers. No wings on struts. Absolute stability at high speed. These were the immutable aerodynamic principles the F1 was designed on. To create traction-enhancing load without adding mass, the team also applied the latest ground force techniques to the car.’
- McLaren Cars

McLaren F1 - aerodynamic

McLaren F1 – aerodynamic

L’aérodynamique « a fait équipe » pour créer le design de la McLaren F1. Très tôt dans l’élaboration de la voiture, les études en souffleries ont été menées et ont été décisives dans le dessin de Stevens. Pas moins de 1 130 séances en souffleries ont été passées à étudier et déterminer les appuis et lignes de la McLaren F1.

Le résultat est tout bonnement exceptionnel car sans aucun artifice aérodynamique, la McLaren F1 peut rouler très vite et générer de l’appui. En effet, tout le travail de l’équipe a consisté à lutter contre la portance à grande vitesse, et aussi à déterminer l’emplacement idéal pour le centre de poussée, qui est le point où convergent les forces aérodynamiques agissant sur le véhicule.

The overall drag coefficient on the standard McLaren F1 is 0.32, compared with 0.36 for the faster Bugatti Veyron.

The normal McLaren F1 features no wings to produce downforce (compare the LM and GTR editions) however, the overall design of the underbody of the McLaren F1 in addition to a rear diffuser exploits ground effect to improve downforce which is increased through the use of two electric Kevlar fans to further decrease the pressure under the car.

A « high downforce mode » can be turned on and off by the driver.

At the top of the vehicle, there is an air intake to direct high pressure air to the engine with a low pressure exit point at the top of the very rear.

The doors on the vehicle move up and out when opened, and are thus of the butterfly type. Under each door is a small air intake to provide cooling for the oil tank and some of the electronics.

McLaren F1 - front side-face / profil avant - open doors / portes ouvertes

McLaren F1 – front side-face / profil avant – open doors / portes ouvertes

‘The dihedral doors are an elegant solution to a complex problem. Beautiful, simple, practical, their wide opening design makes it easy to access the central driving position.’ - McLaren Cars

The airflow created by the electric fans not only increases downforce, but the airflow that is created is further exploited through design, by being directed through the engine bay to provide additional cooling for the engine and the ECU. At the front, there are ducts assisted by a Kevlar electric suction fan for cooling of the front brakes.

There is a small dynamic rear spoiler on the tail of the vehicle, which will adjust dynamically and automatically attempt to balance the centre of gravity of the car under braking – which will be shifted forward when the brakes are applied. Upon activation of the spoiler, a high pressure zone is created in front of the flap, and this high pressure zone is exploited — two air intakes are revealed upon application that will allow the high pressure airflow to enter ducts that route air to aid in cooling the rear brakes.

The dynamic rear spoiler increases the overall drag coefficient from 0.32 to 0.39 and is activated at speeds equal to or above 40 mph (64 km/h) by brake line pressure.

Le moteur de la McLaren F1

“The F1 was born with three goals. One was to solve the problems inherent in most supercars: bad seating position, lack of visibility, terrible pedal offsets, no space to carry stuff in the cabin, poor luggage space, no decent sound system or air conditioning.

“Another was to enhance the driver’s experience. It seemed to me supercar design was being dictated by performance figures, whereas building a really great driver’s car is a much more emotional thing than figures on paper. We knew the F1 would be fast because it would be small and light, but we didn’t dwell on that.

“My original notes called for a V10 or V12 of about 450bhp; it wasn’t until my pal Paul Rosche, BMW’s top engine expert, proposed a very compact 6.0-litre V12 that we knew it would be as quick as it was.

“The third thing was to make the most of the central driving position –
to really focus on giving owners the best possible driver experience. The F1’s layout allowed us to concentrate absolutely on driver location and comfort, and it worked. We found you could move the driver about a foot forward and give him a very low cowl that gave great vision.

“You could also hide all the stray bits and pieces –
washer bottle, ventilation system and even air vents – in the nose so you were left with a pure, fighter-style cockpit, something owners still love.”

“We’d looked at the Lamborghini Countach and the Jaguar XJ220 and knew we didn’t want anything like that.”

- Gordon Murray

Gordon Murray veut absolument un moteur atmosphérique, avant tout pour des raisons de sonorité et de réactivité à l’accélérateur, à une époque où le fameux ‘turbo lag’ pose encore de réels problèmes.

Gordon Murray insisted that the engine for this car be naturally aspirated to increase reliability and driver control. Turbochargers and superchargers increase power but they increase complexity and can decrease reliability as well as introducing an additional aspect of latency and loss of feedback. The ability of the driver to maintain maximum control of the engine is thus compromised.

Murray exige au moins 550 chevaux et un bloc moteur compact : 600 mm de longueur et 250 kilos maxi.

Murray initially approached Honda for a powerplant with 550 bhp (410 kW, 558 PS, 558 ch), 600 mm (23.6 in) block length and a total weight of 250 kg (551 lb), it should be derived from the Formula One powerplant in the then-dominating McLaren/Honda cars. When Honda refused, Isuzu Motors, then planning an entry into Formula One, had a 3.5-litre V12 engine being tested in a Lotus chassis. The company was very interested in having the engine fitted into the F1. However, the designers wanted an engine with a proven design and a racing pedigree.

Gordon Murray contacte d’abord Honda, qui motorise alors les McLaren de Formule 1, mais les japonais déclinèrent l’offre de fournir un moteur V12 correspondant à ses besoins.

‘During this time, we were able to visit with Ayrton Senna and Honda’s Tochigi Research Center. The visit related to the fact that at the time, McLaren’s F1 Grand Prix cars were using Honda engines. Although it’s true I had thought it would have been better to put a larger engine, the moment I drove the Honda NSX, all the benchmark cars—Ferrari, Porsche, Lamborghini-I had been using as references in the development of my car vanished from my mind.

Of course the car we would create, the McLaren F1, needed to be faster than the NSX, but the NSX’s ride quality and handling would become our new design target. Being a fan of Honda engines, I later went to Honda’s Tochigi Research Center on two occasions and requested that they consider building for the McLaren F1 a 4.5 litre V10 or V12. I asked, I tried to persuade them, but in the end could not convince them to do it, and the McLaren F1 ended up equipped with a BMW engine.’

- Gordon Murray

Gordon Murray se rapproche donc de Paul Rosche, qu’il connaît bien pour avoir travaillé avec lui du temps de sa période Brabham.

BMW qui venait d’abandonner son projet de M8,une super série 8 dotée d’un V12… BMW cède donc l’exclusivité de ce V12 à McLaren Cars pour sa F1. Ce moteur est tout simplement exceptionnel et présente des caractéristiques formidables : 6 litres de cylindrée, plus de 600 ch !

Paul Rosche, motoriste chez BMW, conçoit spécialement à l’attention de la McLaren F1 un V12 de 6,1 litres tout en aluminium, compact et ultramoderne, avec calage variable de la distribution, 12 papillons de gaz individuels et une lubrification par carter sec.

Gordon Murray then approached BMW, which took an interest, and the motorsport division BMW M headed by engine expert Paul Rosche designed and built Murray a 6