The Development and Manufacture of a Roof Mounted Aero Flap System for Race Car Applications

This paper describes the effort initiated by the National Association of Stock Car Auto Racing (NASCAR), and joined by General Motors Corporation (GM), Ford Motor Company (Ford) and Roush Industries, Inc. (Roush) to develop and manufacture a roof mounted aero flap system (referred hereafter as “roof flaps”) for race car applications. This system addresses the problem of how to greatly reduce the severity of accidents involving spinning race cars by means of preventing aerodynamic lift-off. There were several NASCAR race car accidents in 1993 that involved cars which became airborne.

A variety of tests and procedures, both inside and outside the wind tunnel environment, were conducted to evaluate and consider possible solutions to this problem. Ultimately, a roof flap system was produced that has significantly reduced extreme yaw lift in race cars. The proof of success of this system has been the virtual elimination of aero lift-off in NASCAR race cars since the introduction of roof flaps, when coupled with previously mandated anti-lift devices, in February, 1994.