A high pressure front
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UK OPERATORS who are testing aerodynamic drag reducing devices in an effort to save fuel might be interested in the latest American thinking.
Wind tunnel testing at the University of Utah has demonstrated tremendous reductions in drag (up to 45 per cent) on large box van semitrailer trucks by adding a long parallel roof duct to the trailer. This duct is about 9in deep and extends the full length of the box van.
The idea is to pick up h pressure air flowing upwt across the windscreen of tractor (or the leading ec of the trailer) and to duct to the rear into the low pr sure area which is crea behind any box-like obj moving at a speed.
Trapping the upward m, ing air stream at the fri keeps the stream from " se rating" or losing cont with the flat roof contour