Segment V9.8: Drag on a Truck

(Related to Textbook Section 9.3.3 - Drag Coefficient Data and Examples)

A significant portion of the power needed to drive a vehicle at highway speeds is lost overcoming aerodynamic drag. Appropriate design of the vehicle can reduce the drag and thus increase the fuel economy.

Because of geometric constraints, little redesign can be done to the rear of a truck to reduce the drag. On the other hand, a simple, well-designed air deflector on the cab can help smooth the airflow past the front of the truck and reduce its drag. However, even with the deflector, there is flow separation at the top leading edge of the trailer portion of the truck. (Video courtesy of the National Research Council of Canada and the Institute for Aerospace Research.)