Abstract
An investigation of the aerodynamic drag of trucks and the drag reductions possible through the use of commercially add-on devices was made on three 1:10 scale models in the National Aeronautical Establishment 's 6-ft.x 9-ft. working section wind tunnel. A series of tests were also performed to determine the effect of trailer modifications which could be implemented by the trailer modifications which could be implemented by the trailer manufacturer. Both the use of add-on devices and trailer modifications produced drag reductions which could provide fuel savings of up to 10 percent for a tractor-trailer and 18 percent for a straight truck at 55 mph.