DEVELOPMENT
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• Gar manufacturers such as Audi. BMW and Ford spend vast amounts on developing slippery shaped models, emphasising their ultra-low drag factors and fuel efficiency.
In recent years, however, truck cabs have become sleeker as their designers have worked hard to soften the frontal features—good examples include the latest Scania 4-Series and the Mercedes-Benz Actros.
Body and trailer builders have also played their part, developing entire suites of addon aerodynamic panelling to improve a truck's wind-cheating outline even more.
They add a thousand pounds or so to a vehicle's up-front cost, but with the high mileages covered by HGVs these days wind-cheating cladding should pay for itself in fuel savings within a couple of years.
Blue-chip operators such as Argos, TNT and NFT have relied on the expertise of Val Dare-Bryan, one of the UK's leading aerodynamics experts, and kit builder AB Airflow to develop cab-roof and body fairings.
Using shaped models, and testing them in wind tunnels, Dare-Bryan has devised smooth systems for refrigerated and boxvan trailers. And having turned his attention to curtainsiders, he's been able to pull an artic's drag factor (Cd) down to 0.39, which is better than many saloon cars.
He's convinced that most of the wind resistance is caused by turbulence underneath and around the sides; indeed the buckles cause very little air disturbance, he believes. This is why Dare-Bryan's latest artic design for NFT includes curvy side valances that extend forward to encapsulate the foldaway landing legs and have openings front and rear.
While maintaining what he calls the thin boundary layer around the artic's sides, the turbulent "dirty" air running beneath the artic is allowed to surge out through the back. With radiused edges and a slight slope on the rear roof, he anticipates fuel savings in the region of 4%.