24 Hours of Le Mans

24 hours of Le Mans (24 heures du Mans) is the most famous sports car endurance race. It is held at Circuit de la Sarthe near Le Mans, France, in the French Sarthe département. It is organised by the Automobile Club de L'Ouest (A.C.O). The first race was held on May 26 and 27, 1923 and has since been run annually in June, with the exceptions of 1956 (July) and 1968 (in September, due to nationwide political turmoils in spring see May 1968), and was cancelled only in 1936 (economy) and from 1940 to 1948 (World War 2).

The circuit

The Le Mans Circuit de la Sarthe is a non-permanent track using local roads. Since 1965, a smaller but permanent Bugatti Circuit was added which shares the pit lane facilities and the first corner with the famous Dunlop bridge with the longer version.

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The track has undergone many modifications over the years. It is most famous for its long straight, a part of the RN138 (Route Nationale 138 - National road 138) known locally as Ligne Droite des Hunaudières, or in English as the Mulsanne Straight.

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The race is run on a non-permanent track which is today over 13 km (8.1 mi) long, using mostly normal country roads. Over the years, several purpose built sections replaced the normal roads, especially in 1972, when the Porsche Curves section bypassed the dangerous former Maison Blanche section between buildings.

Related Topics:
Km - Mi

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Unlike many other races where the speed in curves is more important than top speed, top speed was a critical parameter for being competitive in Le Mans. This led to special body designs like the "Long Tail" bodies pioneered by Charles Deutsch and Robert Choulet. Braking at the end of the straight is also critical; the first use of disc brakes on a car was in a Jaguar racing in Le Mans. Mercedes-Benz still used drum-brake in 1955, but used a special hood as "air brake".

Related Topics:
Charles Deutsch - Robert Choulet - Disc brake - Jaguar - Mercedes-Benz

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The cars were reaching impressive speed in the straight: in 1971, during night practice, a Porsche 917 LH was clocked at a top speed of 386.004 km/h, or about 239.852 mph.

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During the 1970s, top speeds decreased after the introduction of new regulations that reduced the size and power of the engines, while the evolution of aerodynamics allowed the engineers to improve the speed on a lap by increasing downforce and thus increasing speed in curves and reducing top speed. This evolution, which brings less stress on the car, was also favored by drivers because it made the car easier to drive, leading to less violence in acceleration and braking while reduced speed in the straight required less attention and gave more relaxation to the driver. On a 24 hours race these are important benefits.

Related Topics:
1970s - Aerodynamics - Acceleration

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But, by the late 1980s, the fastest cars were again reaching impressive top speeds. In 1988 a WM P87 powered by a turbocharged PRV engine and driven by Roger Dorchy reached the speed of 405 km/h (251.7 mph) during the race. This performance is generally considered as non-significant because it was a media coup by a team seeking budget: the car was tuned for top speed with all air orifices taped, as a result the engine broke soon after. But the next year a Sauber Mercedes C9 reached a top speed around 400 km/h (248.5 mph) without any special tuning during the race, and the FISA felt that it had grown unsafe. Two chicanes were consequently put in place in time for the 1990 race to lower top speeds. Near the end of this straight was an infamous hump, which gave flight to a Mercedes CLR in 1999 during warm-up. The same problem had occurred elsewhere for another CLR twice in practice and race, leading to the withdrawal of the third CLR out of concern for safety. The hump was lowered during the winter before the 2001 race, again in the interest of safety. Although the hump remains, it is greatly diminished from what it was.

Related Topics:
1980s - 1988 - PRV engine - Roger Dorchy - Sauber Mercedes C9 - FISA - Chicane - 1990 - 2001

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A new chicane was introduced in the Dunlop curve for 2002.

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