IRA tests prove it:
Page 15
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sheeting saves fuel
• by Peter Lawton New findings from the Motor Industry Research Association show that tipper operators can save thousands of pounds in fuel by sheeting their load and using underfloor tipper gear.
The MIRA research, sponsored by tipping equipment suppliers Harsh, shows dramatic reductions in drag from fitting a sheet and from using underfloor gear which allows the gap between body and cab to be closed.
Harsh invited Commercial Motor and several operators to see how a half-scale Scania 8x4 tipper was tested in the wind tunnel at MIRA's Nuneaton site, Data gathered from hours of aerodynamic testing in the tunnel was entered into MIRA's fuel estimation spreadsheet which calculated an average improvement in economy amounting to around 9.5%—a significant saving even for lowmileage tipper runs.
Sheeting a tipper with a system like Harsh's Slide 'n' Go gives the most significant improvement, but closing the gap between body and cab by using underfloor gear boosted the gain to as much as 11% in one example tested in the tunnel. The gap difference on the model tested equated to a reduction in the real-world distance between cab and body from 590mm to 120mm.
Watching MIRA's smoke-wand moving around the model, it was clear how an unsheeted tipper acts as a huge air brake, particularly when unladen. Space between the cab and the tipper on a front-end-lifted design created considerable turbulence and drag: air travelling underneath the cab was also sucked upwards into the gap.
The hatf-scale model used at MIRA was heightadjustable to simulate laden conditions and big
enough to provide accurate and reliable results, according to MIRA's aerodynamic expert Adrian 'MON.
• See Fleet Focus on fuel consumption, pages 32-33.