Aerodynamic Revolution

After nearly four decades spent improving the technology and components behind commercial truck development, Skip Yeakel is taking a step backward, so to speak, to work on a project that could change the shape of trailers forever. As the principal engineer in charge of advanced engineering for Volvo Trucks North America, Yeakel is no stranger to life on the cutting edge. He's worked on such groundbreaking

After nearly four decades spent improving the technology and components behind commercial truck development, Skip Yeakel is taking a step backward, so to speak, to work on a project that could change the shape of trailers forever.

As the principal engineer in charge of advanced engineering for Volvo Trucks North America, Yeakel is no stranger to life on the cutting edge. He's worked on such groundbreaking projects as the development of automatic shifting manual transmissions, electronically-controlled diesel engines, adaptive cruise control and electronically-controlled disc braking systems for trucks.

But Yeakel says the trailer aerodynamics project he's participating in this year has the potential not only to permanently alter trailer design but vastly improve the operating efficiency — and even safety — of fleets. “If this technology works like it has in small-scale wind tunnel testing, it will border on revolutionary change for this industry,” he says.

The trailer aerodynamics project, sponsored by the Dept. of Energy's (DOE) Office of Heavy Vehicle Technologies, is part of a design initiative guided by the DOE's Oak Ridge National Laboratory (ORNL) to increase the fuel efficiency of heavy vehicles and reduce highway emissions. Late last year Volvo received a contract from ORNL to evaluate new technology developed and patented by the Georgia Tech Research Institute (GTRI).

GTRI's technology combines the use of aerodynamic surfaces with a “blower” to create positive air pressure at the back of the trailer instead of a vacuum, says Yeakel. The flat rear of truck trailers has been a perennial problem in terms of creating a partial vacuum when the truck is moving — a vacuum that increases drag on the overall vehicle, which in turn leads to more fuel consumption.

Yeakel says that previous attempts to eliminate the vacuum were unsuccessful. “Freuhauf, for example, designed a trailer 30 years ago with what I call a ‘boat tail,’ a 20-ft. extension that tapered to a point, much like the tail on a duck,” he says. “It worked very well in eliminating drag, but wasn't practical for use in a trucking operation. Now, GTRI's technology seeks to do the same thing by forming a ‘virtual’ boat tail that manipulates air flow over the trailer to eliminate drag without physically modifying the rear of the trailer.”

Great Dane Trailers and Volvo will conduct an over-the-road aerodynamic evaluation of GTRI's trailer technology, comparing the fuel efficiency of a 53-ft. trailer equipped with the new technology to one without it. The test run will start at Volvo's Technical Center in Greensboro, NC, and end at the Transportation Research Center in East Liberty, OH, this summer.

While Yeakel is excited about the potential for fuel savings, he's also interested in the impact of GTRI's technology on safety. “By blowing air across the back of the trailer, we may expect to actually improve the handling of these trailers on the road,” he says. “The increased ‘down force’ of that air could also improve the roll stability of trailers. Though the tests will focus on GTRI's wind tunnel results as they relate to fuel savings, we'll obviously be keeping an eye on those related safety benefits, too.”

Yeakel is also enthusiastic about the opportunity to work more closely with his counterparts at Great Dane. “In the past, truck and trailer manufacturers have worked largely on their own. We've built tractors and they've built trailers, even though the two pieces of equipment end up working together as a single unit out on the road,” he says. “I'm hoping this project fosters a greater leap of substantive cooperation between us.”




Each month this column looks at emerging truck technology issues through the eyes of a leading engineer.

Name: Skip Yeakel, Principal Engineer-Advanced Engineering, Volvo Trucks North America

Background: Yeakel received a B.S. in mechanical engineering from Pennsylvania State University in 1963. He began his professional career at Schramm Inc. as a project engineer, followed by a position as manager of experimental engineering for the Autocar Trucks division of the White Motor Corp. (which became Volvo White/GM and eventually Volvo Trucks North America). Yeakel serves on the Intelligent Vehicle Initiative Heavy Truck Platform Committee, an advisory group sponsored by the Intelligent Transportation Society of America.

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