Ground effects for various body configurations of high speed road vehicles.

Results are presented from an experimental study of lift, drag, pitching moment and flow field of a series of round-edged simple bodies of various angles of rake of front and rear underbodies. The bodies are proportioned similar to those of idealized road vehicles such as automobiles, vans and buses. Wind tunnel tests are performed by the running belt method, that is, boundary layer breather, moving road surface and rotating tires. The force coefficients and flow visualization studies indicate the importance of flow regimes characterized by trailing vortices which are determined by angle of rake of rear under body and road clearance. The condition of tires is found to give significantly different lift and drag for road clearance of actual road vehicles. The effects of upper body shape on ground effects are generally small.