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Andy Bacon, boss of AB Airflow Systems, which is based
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in Sandy in Bedfordshire, provides bespoke aerodynamic packages to truck, trailer and body manufacturers, as well as for end users.
The first 10% gain in fuel economy, he says, is relatively easy "You've always been able to gain that with cab aerodynamics and driver training. Getting the rest is where all the work is needed."
Even though manufacturers add their own air management kit, the patented lip on Bacon's cab collars are key. "Most [truck] manufacturers' big tractors are set up to run with a [Continental] 4.0m high trailer, whereas, in the UK, we typically run with 4.2m trailers or higher" he says. "The cab fairing on the tractor is the number one starting point you then move on to having the right cab fairing."
Ironically, better aerodynamic results can be achieved with a smaller, narrower cab fleet tractor than one with a high-datum, 2.5m-wide extra-tall cab. "The best thing people can do with high-spec/roof tractor versus a fleet tractor is to pay the driver more to save fuel," he adds.
Ideally, he continues, the tractor fairing should align the air so it runs smoothly down the side of the trailer. "We're accelerating it, so it runs nicely straight down the trailer. A 200-300mm coupling gap is an acceptable gap, if you make it too small and the driver misses the pin, its back to dealing with damage again," he says. "Likewise, if you make the gap small at the bottom you need it larger at the top otherwise it won't articulate.
"The worst thing you can ever do with side skirts is fill the back in or equally the gap by the landing legs. If you do that, the air will try to spill out and create drag."