BREEZY Air studies may boost fuel economy. (Photo courtesy of FreightLiner LLC)

For one West Coast-based manufacturer, research gained from studying the aerodynamics of heavy-duty trucks will be a critical next step in squeezing efficiency out of cleaner, pricier diesel engines and fuel. On April 13, Freightliner LLC unveiled the world’s first truck-specific wind tunnel, which it financed and built near its headquarters in Portland, Ore.

A subsidiary of Stuttgart, Germany-based DaimlerChrysler, the truck manufacturer claims that the new steel-framed facility was the most-rapidly built and lowest-priced, full-scale wind tunnel on the planet. The 12,000-sq-ft building and wind tunnel were completed in 11 months for about $3 million, one-tenth of the cost of wind tunnels of similar size, says Freightliner.

Freightliner credits these achievements to thousands of hours of fluid-dynamics testing done in the months before any dirt was moved. "You always take risks when building something new," says Matt Markstaller, the owner’s project manager. The firm minimized its risks by engaging engineers from in-house, Portland State University and Mercedes-Benz in Germany. They all pitched in on "computerized design work that simulated actual operating conditions" in the tunnel, Markstaller says.

Rabi Mehta, a National Aeronautics and Space Administration research scientist, consulted on materials, interior shapes and equipment. The wind tunnel was the first for Portland-based designer VLMK Consulting Engineers and general contractor Mega Pacific, according to Kaz Kawamoto, Mega Pacific project manager.

The project team also economized on key components. Ten commercially available, 72-in. fans behind the test vehicle move air through the the roughly 90-ft-long tunnel. The fans draw in air at 35 mph and the velocity of air increases to 65 mph as it moves through a contraction cone and toward the test vehicle.

Two small ramps hold vehicles against a load cell, which delivers drag-force measurements to test observers. Engineers can model different vehicle types, including tractor-trailers, work trucks, school buses and commercial vans.

Michael von Mayenburg, Freightliner’s senior vice president of engineering and technology, says the tunnel will be an important tool. By 2007, he hopes to cut drag resistance on trucks by 15% and boost fuel economy by 5%.

Freightliner’s timing couldn’t be better. Its goals coincide with an Environmental Protection Agency rule change in on-road diesel emissions, slated for January 2007 (ENR 3/1 p. 24). With fuel-efficiency still a question on 2007 engines, gains made in the wind tunnel may blow away when the technology is adopted. In such a scenario, however, Freightliner says it still would have an advantage over competitors unable to offer equally "slippery" vehicles.