downforce

What makes a racecar spontaneously rip a 360 backflip? A perfect storm of hills and tailgating, that’s what. In this case, driver Yannick Dalmas, racing for Team Porsche in the 1998 Petit LeMans at Road Atlanta, was drafting the car in front of him while zooming over a rise. As he crested the hill, the car’s suspension pulled up, allowing more air to flow under the car and creating lift. Simultaneously, the draft from the car in front of him interrupted the airflow over the nose of Yannick’s car, sapping the much-needed downforce that kept the car in contact with the pavement. Without that downforce, there was nothing to stop the car’s nose from continuing upward once it started. After that, it’s pure physics opera: The nose of the car leaves the draft zone and enters the airstream, which accelerates the lift and pushes the nose backward while the weight of the rear-mounted engine continues its forward momentum. Voilà! A fantastic, white-knuckled twirl that—luckily—sustained enough momentum to end upright. Must have been an awesome ride. (Dalmas walked away uninjured.) —Martha Harbison

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