October 30, 2012 10:00 AM, EDT

Truck Makers Develop Improvements in Aerodynamics for Tractors

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While the largest aerodynamic changes are happening on trailers, truck makers said their products also are being made more air-efficient, which has a significant effect on the entire tractor-trailer combination.

To improve the aerodynamics of their vehicles, manufacturers are using computational fluid dynamics, or CFD, a mathematic tool used to predict how a fluid will flow around a given object. This prediction can help truck makers develop and hone aerodynamic improvements with unprecedented ease and effectiveness, manufacturers said.

T.J. Reed, director of product marketing for Freightliner Trucks, Portland, Ore., said the company “introduced the Cascadia Evolution in 2012. Available in day cab, mid-roof and raised-roof configurations, it offers a variety of advanced aerodynamic features that significantly increase efficiency and overall performance.”

The Cascadia will go into production in the first quarter of 2013.

Reed said specifics include, among other developments, a bumper air dam and other bumper-related enhancements, cooling enhancements and improvements to air flow around or over the windshield, antennas, side fairings and extenders, mirrors, and even rear wheel covers.

“The Cascadia Evolution delivers up to an additional 7% improvement in fuel economy over an [Environmental Protection Agency] 2010-compliant Cascadia equipped with a first-generation aerodynamic package,” Reed said.

At Kenworth Truck Co., Kirkland, Wash., the biggest news is its new T680, introduced last year at the Mid-America Trucking Show in Louisville, Ky. Design director Wally Peltola said aerodynamics played a major role in the vehicle’s design.

“Engineers developed, tested and retested every surface,” Peltola said, “Even the marker lights were made flush so as not to disturb the airflow. Kenworth engineers’ design philosophy was that every line should be flowing, and every surface should look clean and purposeful.”

Jerry Warmkessel, highway product marketing manager for Mack Trucks, Greensboro, N.C., said his company “configures the wheelbase and fifth-wheel offset to ensure minimum cab-to-trailer-swing clearance.”

Warmkessel described Mack’s aerodynamic development process as beginning with CFD studies on computer, followed by testing full-scale trucks with mock-up parts in a wind tunnel.

With the best, most effective shape, “permanent tooling is made to produce production-quality parts. Finally, durability testing of the production parts is conducted to ensure they meet Mack’s rigid durability criteria,” he said.

Peterbilt Motor Co., Denton, Texas, introduced its 579 model at the 2010 Mid-America Trucking Show.

“Through computational fluid dynamics and subsequent wind tunnel testing, fuel economy was maximized and aerodynamic efficiency was achieved,” said chief engineer Landon Sproull.

Frank Bio, product manager for Volvo Trucks, Greensboro, N.C., said his company recently introduced improved aerodynamic components for its VN model.

“The new fuel enhancement package includes redesigned mirror heads with aerodynamic shrouds and arms, redesigned hood mirrors that also increase visibility, and a new bumper and side fairings,” Bio said. “VN day-cab models also offer a more aerodynamic roof fairing and sun visor.”

Scott Perry, of Ryder System, Miami, was asked about significant fuel-economy improvements in its fleet from the recent aerodynamic enhancements to the trucks it recently bought.

“We have introduced thousands of new tractors built by various manufacturers in the past year,” said Perry, vice president of supply management for Ryder’s fleet management solutions division. “Those vehicles have varying degrees of sophistication in their aero packages, based upon the application and configuration of the vehicle.

“The longhaul sleeper tractors with full aero packages are seeing very strong fuel-economy improvement,” Perry said, “but those units are also typically spec’d with fuel-saving gear ratios and transmissions, coupled with the latest SCR engines, which will all have an impact on total fuel economy.”

International Truck & Engine Corp. did not respond to requests for comment.