Automotive

Mercedes Benz showcases its Aero Trailer concept in Belgium

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Mercedes' Aero Trailer, being pulled by an Actros tractor unit
Mercedes' Aero Trailer, being pulled by an Actros tractor unit
Mercedes Actros tractor unit
Mercedes Actros truck pulling the Aero Trailer concept
Mercedes Actros tractor initial concept sketch
Mercedes Actros tractor impersonating a Deceptecon
Mercedes Actros truck pulling the Aero Trailer concept
A Mercedes Actros truck, pulling the Aero Trailer concept
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Being in Belgium in November for a truck show may or may not be your cup of tea/mug of Java, but Mercedes is at least doing its best to make the "Trailer 2011" exhibition interesting. The truck design world moves at a glacial pace compared to the consumer automobile business, and new models have to provide serious and significant commercial improvements if they are to be accepted by the trucking fraternity. Coming off the back of the well-received launch of its new Actros heavyweight tractor unit, Mercedes brought along a trailer concept design that aims to match and extend the significant commercial and environmental advantages of that unit. It looks cool, too.

There's no getting around the fact that trucks are big square boxes that take a lot of energy to plow through the air. The turbulence you feel when overtaking one on the highway is ample evidence of that.

Mercedes has managed to reduce the frontal wind resistance of the Actros tractor unit by 15 percent, through 2,600 hours of wind tunnel testing. The results can be seen clearly on the front face of the unit, which sports a number of subtle winglets, a plate, and channels to control airflow - the influence of all those millions spent on Formula 1 aero research, no doubt.

The logical next step is clearly to apply the same rigorous wind-tunnel work to the trailer half of the equation, and that's exactly what Mercedes has done. The interior dimensions of the trailer have to be maintained, of course, so a front air dam reduces the distance between tractor and trailer. The application of a number of precisely-calculated curved panels to the outside and underneath of the trailer channel air to a striking rear diffuser. In addition, there is a 400-mm (15.75-inch) extension to the rear in the form of a "boat-tail," that reportedly brings extensive aerodynamic benefits.

Mercedes Actros truck pulling the Aero Trailer concept

In total, Mercedes claims an additional 18 percent wind resistance reduction in the tractor-trailer combo, which should equate to a five percent reduction in fuel use. For the average year of a busy trailer, that represents 2,000 liters (530 US gallons) of fuel and an astonishing 5 tons (4.5 tonnes) of CO2.

The trailer is still a concept at this stage, since the extension at the rear will require a change in legislation. The reported benefits are so significant, however, that this may be achieved in due course.

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10 comments
professore
Looks alright, but let us hope that the designers pay attention to more than just the front of the vehicle. One of the most hazardous aspects of large trucks on the roads is the incredible quantity of spray that is thrown up from the roads in bad weather....and of course solid objects such as stones that can damage or shatter the windscreens of following vehicles. This is one requirement that warrants strong legislation!
Calson
Surprised that Mercedes engineers failed to provide a design that makes use of a movable front bumper and cowl to improve airflow at the cab. This is not a new concept and 90% of the time the trucks are moving down the open road and having the front protrude out an extra meter would not affect maneuverability in the slightest.
The rear extensions also need to be designed to either fold back or otherwise collapse when the truck is moving back to a loading dock to load or offload its cargo.
To bad that the German engineers spent all their time at the wind tunnel and did not spend any time out in the world talking to truckers or even going online to research movable fairings. The Japanese engineers patented designs for a movable fairing for high speed trains and the same approach would work for trucks.
2VT
While these European trucks are smaller than the USA\'s 40 ton and up to 80 ft long (auto transport trucks) limit, there is a company here in the USA that does use rear fairing (that fold away for docking) as well as side skirts (affects the blow-by spray as well as aero). Sadly the statement that the USA truck designers advance at a glacial pace is painfully true. That being said however, Freightliner has had for some time now a Hybrid class 6 truck (local delivery type). Pretty cool actually as it pulls silently away before the big diesel engine fires up. Don\'t know what the reported fuel mileage is but a normal one is about 4-6 mpg. However, people complain that the initial costs make the benefits take too long to reap. So I guess it\'s still ok to make the rest of the world wealthy. Business as usual.
Slowburn
I worry that the enclosing the tires would make the tires and brakes prone to overheating.
re; professore While I find the spray kicked up by trucks massively unpleasant when passing or being passed by a truck in wet conditions, I do not find it to be excessive given the amount of rubber on the road. How much are you willing to pay to reduce the spray from your car.
re; 2VT Given that most electric Hybrid systems will not pay for themselves over a reasonable length of time and the fact that the batteries are an ecological disaster, I\'m not disappointed in slow sales.
Pat Kelley
What\'s sad about this article is the comment that legislation is required before the design can be used. We are so over-regulated it\'s pathetic. There are lots of good ideas out there that could make life more efficient, cleaner, and cheaper being held up by petty bureaucrats.
TogetherinParis
Legislation IS required to implement low cd technology. The engineers at Mercedes Benz failed to identify the open wheels of their tractor unit as problematic for aerodynamic efficiency. Enclosing wheel wells increases vehicle efficiency as it diminishes more than just the inconvenience of excessive road spray, it also diminishes drag and, of course, roadway noise. There is no reason that loud wheels on our public roads should be tolerated. Truck tires on pavement are, by far, the worst offenders. Sound deadening insulation should be applied over every wheel well. Quieting down our vehicles (and roads) will improve property values and benefit the poorest among us who live within earshot of interstate highways. And the \"cost\" will be a more efficient infrastructure. When we get really good at aerodynamics, we can export our excess oil. So why does the market not insist upon aerodynamic vehicle competence? Sellers do not include externalities like the social costs of energy economic dependence upon savage oil nations. You see, the market places any sound deadening insulation around the cab, not the sources of noise on the vehicle. This is because drivers of trucks are never fined or sued for their road noise and vehicle quietness is determined within the driver\'s compartment only. Since there is no market penalty for noise, noise does not decrease. Myopic libertarian ideologues never seem to notice troublesome externalities like air land, and water pollution, foreign energy dependence, noise, etc.
bf_308
Professore and Calson, you need to KNOW the Legislation before you talk about it. The Law for overall Vehicle dimensions (in EU) are very clear and cannot be changed. Adding moving fairings to extend the length of the vehicle is prohibited by Law. This is not only a requirement it is also detrimental to the fuel consumption. US Truck manufacturers are now taking streamlining and aerodynamics seriously and they have a lot of space to play with on Tractor units that are already more streamlined than European Trucks that have practically no space to play with. Regarding road spray and flying stones..........there has been legislation in for some time and is regularly updated as time goes on. The only way to make EU Trucks more economical is to extend the front of the vehicle longer, albeit less than the US Trucks. White have been making a \"Droop snoot\" nose on some of their Trucks for some time............ We are waiting for the Bureaucrats to change some things for the better and let Engineers do their job. Its gonna take some time more.
Slowburn
re; TogetherinParis
Overheated tires and brakes will kill far more people than the thrown rocks and wet weather spay.
Gregg Eshelman
The Peterbilt 372 COE was an aerodynamic model of their cabover semi tractor. Built between 1988 and 1993, it was unusual in that the front of the cab was very smooth and dramatically curved. Even with the typical split, flat windshield (angled back more sharply than conventional cabover designs) it achieved better than 10 miles per gallon.
Customer resistance to the design was high, some sources say fewer than 800 were built.
Apparently Peterbilt buyers were much more resistant to change than Kenworth buyers. The 1985-2007 Kenworth T600 was an almost immediate success, even though it only almost, but not quite, reached 8 MPG in its initial version.
The way to gauge the efficiency of cargo transport is in ton-miles per gallon, or ton(metric)-kilometers per liter.
Weight times distance divided by fuel used. (WxD)/F
A very slick but underpowered truck may be able to get a high unloaded MPG, but load it up and it\'ll do worse (WxD)/F than an aerodynamically \"dirty\" truck with a huge but under-stressed engine.
It\'s worked for aircraft, the Lockheed Constellation got very good efficiency for its time by using four of the biggest radial engines available. They never had to work hard and (once the bugs were worked out) could run longer between overhauls than smaller, higher stressed engines on other aircraft.
BigJohn Trucking
There\'s an American Company, ATDynamics ( www.ATDynamics.com ) that already has a commercial product that saves 6% fuel: The Trailertail (what Mercedes is prototyping).
Perhaps, Mercedes should team up with ATDynamics since they already have a proven commercial product already streamlining thousands of non-aerodynamic trailers?...
FYI - In the US there is a law to allow for a 5 foot aerodynamic extension so long as you\'re not carrying cargo. Europe should get on board updating their old laws.