The Aerodynamic Characteristics of a WRC Rally Car at High Slip Angles

Rally cars are frequently operated at high speeds on loose road surfaces and significant slip angles are achieved when cornering. A wind tunnel test procedure is presented which allows those slip angles to be accommodated whilst maintaining contact between the tires and the wind tunnel's moving ground plane. It is shown that as the slip angle is increased both the drag and lift increase whilst the centre of pressure moves rearwards. Simulations are presented which evaluate the effect of those aerodynamic changes upon the overall performance of the car over a rally stage.