Le Mans Prototype (LMP) cars, built by manufacturers such as Audi and Peugeot, are capable of remarkable straight line and cornering speeds. Get them sideways at speed, however, and the very aerodynamic enhancements that make them fast in corners also make them prone to getting airborne.
The video below shows what happens when a Le Mans prototype car gets sideways during a race. The driver in this horrific 2008 crash, Stephane Ortelli, escaped with only a fractured ankle, but the video illustrates the problem with conventional LMP cars.
As Autoweek explains, when turned into the wind, the wheel arches of an LMP car generate sudden high pressure, enough to lift the car from the track. Even a few inches is all that’s required, since the aerodynamic underbody (which creates negative pressure under normal circumstances) then acts as a sail.
The governing body of the 24 Hours of Le Mans race, the Automobile Club de l’Ouest, is looking to make LMP cars safer in 2012, following a rash of spectacular incidents involving Peugeot LMP cars in the lead-up to the 2011 season.
As of April 1, 2012, all LMP cars must use “fender holes,” measuring 7.9 by 9.8 inches, atop the front fenders. While this exposes much of the car’s front tires, it’s believed that it will also make the cars more stable if turned into the airstream, by venting the sudden high pressure.
Critics point out that the change will ultimately reduce downforce and increase drag, while also changing the car's center of gravity. Since the rule has already been adopted, don’t expect the Club de l’Ouest to change its mind; however, teams refusing the change will still be allowed to compete, but must suffer a yet-to-be-determined weight penalty.