Over-the-Road Tests of Sealed Aft Cavities on Tractor Trailers

A series of over-the-road tests have been conducted to evaluate and optimize sealed aft cavity geometries for drag reduction on tractor trailers. Several test trucks and methods were used to conduct road tests at various sites in northern New York. The results obtained on back to back repeat runs indicated a potential savings of 0.6 mpg for an optimized four-sided configuration. The sealed aft cavity geometry that provided the best performance was found to have a 15 degree inset on the side and top panels and a 7 degree inset on the bottom panel. Recommendations for conducting similar tests and how to avoid problems are also presented.