Feature Article: The Dynamics of Aero
A former owner-operator, Andersen wanted to solve the problem of rain spraying from rigs on the highway. He came up with a quarter-inch-thick flap made of Dupont high-grade nylon that lets water and air through – a design some customers have called a “Texas fly swatter.”
“When the air goes through, that’s how you achieve the savings,” he says. “Every mud flap mounted at the bottom of the trailer is wasting fuel. It’s creating drag.”
Flaps come in two sizes – 24-by-24-in. and 24-by-30-in. Andersen says the key is to allow as much space as possible above the flap for airflow.
Savings with SmartWay
In recent years, the involvement of the U.S. Environmental Protection Agency with its SmartWay program has also refocused attention on aerodynamics and other strategies to improve fuel economy. To learn more about SmartWay commercial partners and potential cost savings, visit www.epa.gov/smartway
Aerodynamic device websites
Air Tab LLC: www.airtab.com
Andersen Flaps: www.ecoflaps.com
Freight Wing: www.freightwing.com
Laydon Composites: www.laydoncomp.com
Nose Cone Manufacturing: www.nosecone.com
Silver Eagle Manufacturing: www.silvereaglemfg.com
Smoothing airflow under the trailer
Learning how to redirect air under the trailer became such an obsession with Bob Henderson that he went to Oregon State University and graduated with an engineering physics degree in 2001.
Henderson’s approach is the AirWedge, an aluminum device attached beneath the trailer in front of the axles. Instead of air swirling in back of the trailer and rain spray splashing out the sides, the product moves it out the back. “It rechannels the air underneath the trailer, does a little compression on it and squirts it under the trailer axles out the back and directs it toward the road,” he says.
Henderson hatched the idea while driving a truck in the 1970s and started a company, Airman Inc., to make the product. He runs the company after hours from his day job as an engineer for a metals company.
Tom Severn, an owner-operator from Medford, Ore., had the AirWedge installed on the 53-foot reefer trailer he and his wife pull for Lund Trucking of Chehalis, Wash. Lund owns the trailer, but Severn paid for the device to improve the fuel economy of his 2005 Peterbilt 379.
“Before I put the unit on, I was averaging a solid 5.9 mpg,” Severn says. “Even with this truck, I’ve picked up two to three tenths, depending on the weather and load. I paid $2,500 for it and it paid for itself in six months.
If you can’t get a return on investment between six months and a year, it’s difficult to rationalize spending the money.” He says the device also reduces spray and improves the trailer’s handling by calming down the wind at the back of the trailer.