Aerodynamics of Race Car Liftoff

<div class="htmlview paragraph">Recently, the off-design aerodynamics of race cars has gained increased attention due to several incidents involving race car liftoff. Although these incidents are rare and usually are a result of an earlier contact, the study of vehicle's high angle of attack aerodynamics may influence future safety related regulations. Therefore, the first portion of this study examines available liftoff data in the open literature on a variety of race cars. This data indicates that prototype race cars have a higher lift slope than open wheel race cars due to their larger underbody area. In the second part of this study a quarter scale model of an Indy car was tested to generate similar data on an open-wheel race car. Both the previous and current data indicate that race cars under normal racing conditions have sufficient front downforce to eliminate the possibility of liftoff. Only when some sort of collision or other contact lifts the vehicle front by several degrees can the aerodynamic lift overcome the weight of the car and result in an unstable pitch up. The available data suggests that by using less ground-effect dependent front downforce devices, the risk of vehicle liftoff is reduced. In the case of open wheel race cars, some sort of peripheral bumper limiting wheel entanglement could significantly reduce the chain of events leading to vehicle liftoff.</div>