Posting in Design
Thermoplastic composite TrailerTales from ATDynamics have been shown to cut fuel use by at least 6.6 percent for high-mileage tractor-trailers.
Northeast trucking company Braun's Express has become the first trucking company in the region to invest in technology from ATDynamics that will retrofit its high-mileage fleet to become more fuel-efficient.
ATDynamics of South San Francisco, Calif., has developed tail farings, known as TrailerTails, that are made out of thermoplastic composites. The farings extend the rear of a semi-trailer by four feet, streamlining the airflow and reducing the fuel consumption of tractor-trailers by 6.6 percent, according to testing. The technology is compatible with major refrigerated and dry van semi-trailers designs, and they fold down automatically when not in use, so that they don't get in the way of access to the trailer back doors.
Braun's Express has installed 10 TrailerTails on what it describes as its "most utilized" trailers, those that travel an average of 50,000 miles annually up and down the East Coast. The company said it is expecting about 10 percent improved fuel efficiency.
Noted ATDynamics CEO and founder Andrew Smith:
"Over 5,000 TrailerTails have been ordered by dozens of trucking companies over the last 12 months as the industry realizes the fuel-savings potential. But the adoption of TrailerTails by our first New England-based feel customer is an important milestone. It provides that TrailerTails were designed to operate easily even in the harshest New England winters."
The video below offers a demonstration of how the farings work:
Sep 22, 2011
I wonder why they don't complete the fairing by putting skirts on the wheel wells. That would also reduce the spray generated by the trailers.
If my memory serves me correctly most aerodynamic drag studies show that under 100 mph that this form of drag has less than a 6% affect on efficiency. This was why many auto manufacturers moved away from the tear drop shapes - because at highway speeds it just didn't matter that much to fuel efficiency or speed. It's why you see Indy drivers giggling at production hwy. cars with spoilers. If all this is correct, wouldn't it make it near impossible for a truck with and extremely angular tail fairings to reduce fuel consumption by 6% at 70 mph? Some photos of a wind tunnel smoke test might clarify this - but I suspect it would just counter the claims. Put me down as extremely skeptical of a 6% fuel efficiency increase claim.
Skirts on the trailers have become common. I've only seen the tail fairings on Mesilla Valley Transportation vehicles running on I-10 in the last few months. (There are several MVT trucks in the video.) In addition to the tail fairings and skirts, MVT rigs also have smooth wheel covers. (Some of the trucks in the video have these, as well.) I'd love to see some real-world statistics on the fuel savings.
Rather than moving to a radical truck/trailer design that would not be compatible with existing standards, this is a nice simple approach that can modify the millions of trailers on the road today. Trucking companies will show a much faster savings on fuel usage. It is better for the environment to see a rapid and broad drop in fuel burned by millions of trucks verses a slow migration of a few thousand fuel efficient trucks and trailers per year. This can buy time to allow that slow upgrade/replacement process to happen naturally as equipment wears out. Verses a costly government forced migration.
The main reason for the uncovered wheel wells is that the "tandem" rear axles slide backwards and forwards a particular distance to help balance the weight between all axles on a tractor-trailer combination. This way, the shipper's can maximize the load and keep the meet the weight limits on each particular axle or set of axles. We have installed a couple of different types of trailer fairings and have witnessed a reduction in spray without the wheel wells being covered. Plus. most states, if not all, require mud flaps that aslo reduce the spray coming off of thetires on the rear axles.
Check this out for some test results. http://www.freightwing.com/test/NRC_Wind_Tunnel_Test_SAE_Paper.pdf