Outwit the wind

Aerodynamic devices are designed to allow air to move swiftly around moving objects. WILLIAM GEORGE learns more about the effectiveness of aerodynamic devices on trucks

Aerodynamic devices act as a wind-management system. They assist with speed, stability and the reduction of fuel consumption and emissions caused by wind acting against the moving body. The main function of an aerodynamic device is to reduce the energy required to move the vehicle through the air.

Because the air affects the movement of the vehicle, attaching an aerodynamic kit allows the smooth airflow around the vehicle’s body. The United States Environmental Protection Agency (EPA) states that fitting aerodynamic devices to truck trailers can save fuel by minimising the drag.

According to the director of Aero Truck, Cameron Dudley-Owen, the most common and effective aftermarket device is an aero kit fitted to the roof of the vehicle, which deflects the wind flow over the top of the body.

“The most effective design includes cab extenders, which flow the air along the sides of the truck body more effectively. A less efficient aerodynamic device is smaller and is fitted to the truck body, or the trailer,” says Dudley-Owen.

“Aerodynamic devices are well suited to vehicles where the body, or the trailer, have dimensions that are larger than that of the cab,” says Dudley-Owen.

“The effectiveness of the roof-mounted aerodynamic kit will help reduce fuel consumption by approximately eight to ten percent. Other factors affecting fuel consumption are speed and the driver’s skills,” he adds.

Dudley-Owen suggests that fitting a complete custom-made kit gives the best results. Thus, it isn’t advisable to purchase small pieces of aerodynamic devices, as that will result in inefficiency.

“The cost of an aero kit depends primarily on the size of the vehicle. The time it takes to recoup the cost of the unit depends on the distance that the truck travels,” says Dudley-Owen.

What is the difference between aerodynamic devices manufactured overseas and those produced in South Africa? Dudley-Owen says that the major difference is in the dimensions of the kits. South African legislation allows for vehicles to be 4,3-m high and 2,6-m wide, while overseas kits are designed for vehicles that are 4,1-m high and 2,5-m wide.

“There is a notable difference in these sizes and therefore the performance of the kits. Truck operators would be well advised to take note of this when considering purchasing aerodynamic devices for their vehicles,” he concludes.