An evaluation of the aerodynamic drag reductions produced by various cab roof fairings and a gap seal on tractor-trailer trucks.

This study was conducted using one-eight-scale models in a wind tunnel at a Reynolds number of about 25 percent of that of full scale trucks at 50 mph. Reductions of up to 35 percent of the zero-yaw drag coefficient, and of over 25 percent of the wind-averaged drag coefficient were obtained.