Abstract
An American company is now convinced that a fairing on the cab roof of a commercial vehicle is more effective than the airshield wind deflector normally used. It would appear that it is also more effective in cross-wind conditions. The aerodynamics of an articulated vehicle is more complex and Rudkin Wiley has developed a gap-seal (to fit between tractor and trailer) which is a steel braced flap of polyethylene that cuts down air swirl. Tests have recently been carried out on these devices but no with and without data were available.