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Split wind vane saves fuel
Page 52
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by CM reporter FUEL SAVINGS of up to 8 per cent are claimed for boxvans and semi-trailer vans fitted with a WD Mk9 wind foil designed by Mr E. K. Hanna.
The device is to be marketed in the UK by PEM Trailers Ltd, Wallisdown Road, Bournemouth, Dorset. It consists of a continuous vane which runs around the leading edge of the vehicle's bodywork.
The air colliding with the trailer body is divided into two separate streams before it flows down the body sides. Air passing from the vehicle front between the vane and body is partially compressed and then accelerated by the venturi profile achieved by the location of the vane relative to the body leading edge. The overall effect is to produce a lubricating layer of air on the sidewalls and roof and cut down air turbulence.
Air passing over the vane is simply deflected to the rear of the vehicle, the side and roof panels being already " insulated " by the lubricating stream.
The vane is bolted to the body and projects 229mm (9in) forward of the body line and stands 13mm (0.5in) proud of the side wail. On many applications the vane could push the vehicle width beyond the 2.5m (8.2ft) legal maximum.
The WO Mk9 deflector vane splits the air flow into two streams, A and B, the latter providing the lubricating layer to reduce turbulence,