Truck makers showcase aero research

The Truck Manufacturers Association and Freightliner, International, Mack and Volvo this week showcased the fruit of two years of aerodynamics research outside the Washington headquarters of the U.S. Department of Energy, which helped fund the project.

The goal of the collaboration was to “get government and industry working together” and to share the results among participating truck makers, says Patrick Charbonneau, International vice president of government relations.

All the parties got together and brainstormed as the research progressed, says Srikanth Ghantae, Mack lead design engineer.

“Implementation of the results of this research could ultimately save nearly 1 billion gallons of fuel annually,” says Robert Clarke, president of TMA, which organized the project.

“Even a crude prototype tractor-trailer gap device improved fuel economy 1 percent,” Ghantae says. “If we optimized it, we could double that gain.”

Subtleties on display in Washington on Tuesday, Nov. 14, included a small outward angle at the rear of the side skirts on the International ProStar and an unusual wheel-and-axle fairing on the trailer behind the Volvo. Mack had a boat tail that folded so the driver could open the trailer doors fully when getting ready to unload. Freightliner showed improved mirror designs and plastic glass panels that demonstrated both airflow around mirrors and the paths taken by raindrops.

Wind-tunnel tests proved that reducing turbulence around mirrors and windshield improves visibility by reducing the number and velocity of raindrops hitting the glass, says Freightliner’s Scott Smith. Also proved: Since mirrors are focused at different angles on different sides of the truck, their shape should be different from side to side; and mirrors have no one-size-fits-all aerodynamic shape, as the ideal depends on airflow patterns around the particular cab, Smith says.

One of International’s partners on the research project, Wal-Mart, already has put into service a trailer incorporating some of the improvements, says Ron Schoon, International chief engineer of aerodynamics.

Compared to all the work the industry has done through the years on tractor aerodynamics, relatively little has been done on the trailer, Schoon says: “There is still an awful lot of opportunity in the area of tractor and trailer integration.”

“At the present state of the art, there are larger gains to be made at the back of the bus,” says Skip Yeakel, Volvo principal engineer for advanced engineering. Accordingly, Volvo showed off an air deflector designed to smooth airflow around the rear axles and tires.