Porpoising is a well-known problem in race cars, able to downgrade performance, manifesting itself as a mainly bouncing oscillation, due to dependency of aerodynamic downforce to ride height. Different switching mechanisms can explain the onset of such self-excited oscillations, in which ground effect plays a crucial role. This study investigates a possible cause of instability occurring in the aerodynamic load enhancement region, just before static stall of the diffuser appears. A preliminary analysis is presented, with the aid of stability maps, based on minimal models including interaction between non-stationary aerodynamic loads and suspension dynamics. The results suggest possible improvements of stability by fine-tuning of structural and aerodynamic coefficients.

Porpoising is a well-known problem in race cars, able to downgrade performance, manifesting itself as a mainly bouncing oscillation, due to dependency of aerodynamic downforce to ride height. Different switching mechanisms can explain the onset of such self-excited oscillations, in which ground effect plays a crucial role. This study investigates a possible cause of instability occurring in the aerodynamic load enhancement region, just before static stall of the diffuser appears. A preliminary analysis is presented, with the aid of stability maps, based on minimal models including interaction between non-stationary aerodynamic loads and suspension dynamics. The results suggest possible improvements of stability by fine-tuning of structural and aerodynamic coefficients.