THE INFLUENCE OF AERODYNAMIC EFFECTS ON CAR HANDLING

A moderately sophisticated linearised mathematical model of a passenger car has been developed. The model includes the following: (a) lateral, yaw and roll degrees of freedom of the body; (b) steer degree of freedom of the front wheels; (c) front and rear suspension kinematic properties; (d) steering system compliances and gear ratios; (e) tyre forces and moments in response to sideslip and camber; and (f) dynamic response characteristics of the tyres. The complete set of aerodynamic forces and moments are added to this basic model. Data typical of a luxury passenger car and an on/off road vehicle are used to generate predicted results for two aspects of behaviour: (a) high speed straight running stability; and (b) transient response to side wind conditions. Sensitivity analysis is used to highlight those design parameters which influence the vehicles handling response most strongly. The paper concludes by specifying the parameters that the designer might use to optimise vehicle handling behaviour under straight running and side wind conditions. (A) For the covering abstract see IRRD 870290.