Energy Efficiency

Published on January 9th, 2014 | by Christopher DeMorro


An Aerodynamic Trailer Design More Than Doubles Fuel Economy

January 9th, 2014 by  

Originally published on Gas2.

airflow-bullet-truck-5America’s reliance on big rigs to transport tens of thousands of pounds of goods from one end of the country to another comes at a high cost in both fuel and pollution. AirFlow Trucks has debuted a big rig design that more than doubles the fuel economy of traditional semi-trucks, relying mostly on aerodynamics and efficiency improvements rather than fancy hybrid tech.

While traditional big rigs expend as much as 50% of their power just pushing air out of the way, the AirFlow BulletTruck has a much more aerodynamic design that allows it to slice through the atmosphere with ease. While hauling a 65,000 pound load from Connecticut to California, the BulletTruck big rig managed to average 13.4 MPG, more than double the 6 MPG or so most big rigs average while on the road. That’s even better than the Supertruck, another aerodynamically-enhanced big rig with better fuel economy.

In addition to a massive tapered nose and tire-hiding curtains, the BulletTruck uses LCD screens to replace electricity-hungry manual gauges. A hybrid air conditioning and power steering unit reduces parasitic load, and video cameras replace the massive mirrors all semi-trucks currently require. That one change alone can result in a massive MPG gain, and its even better than some hybrid diesel-electric trucks tried out by Coca-Cola.

AirFlow claims that if the industry adopted its BulletTruck design, it would save 7.5 billion gallons of fuel and 21 million tons of exhaust emissions annually. And all without any crazy-expensive hybrid engine technology or alternative fuels. Just a few small changes can save a lot of fuel, as it turns out, and the BulletTruck has a lot to teach the trucking industry.

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Source: Green Car Reports

Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

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About the Author

A writer and gearhead who loves all things automotive, from hybrids to HEMIs, can be found wrenching or writing- or else, he's running, because he's one of those crazy people who gets enjoyment from running insane distances.

  • John

    1) These side skirts cause all sorts of problems that this study missed.
    When you cover the truck and trailer wheels like this, the heat can not escape and the axle bearings fail at a fraction of a normal life.

    2) These skirts will rip right off at the first dip, rail crossing, submerged dock, or any severe change of road grade due to the simple fact that these are long wheel base vehicles.

    3) Aerodynamic benefits can only be measured at high speed, (>60 MPH).
    The average truck speed is below 40 MPH. Half of the time the trailer is just sitting around waiting to be loaded or unloaded, and on the road, it sits in traffic in the metropolitan areas.

    The best way to save truck fuel would be to allow trucks to carry more load at a time and add a third axle to the trailer and truck to reduce the weight on each tire to protect roads and bridges better than today by reducing the load per wheel.

    • Bob_Wallace

      1) Hard to believe. There is still a lot of air flowing beneath the truck.

      2) Make them out of “hard rubber” and mount them so that they are flexible – can ride up over a hump. If nothing else, hinge them and drop them when on highways.

      3) Ever drive on an interstate highway? There are trucks out there hauling ass for long miles. That’s when they burn fuel. They don’t burn fuel when they are parked.

    • 1) If that’s true (which I doubt) then your bearings are crap and you should buy better ones.

      2) Maybe if you’re driving a limo, trucks are not that low to the ground, and you can see the ones on this truck could drive over a curb without getting bumped. And if they do go over something higher, they appear to be flexible along the bottom, like most side skirts are. Easy fixable or replaceable sheets of fiberglass or something.

      3) Aerodynamic drag increases with the cube of speed. Benefits are small at low speed but rise exponentially. These are big long haul trucks, not two axle cab-over delivery trucks with short trailers. But even those trucks could benefit.

      • Doug DeNasty

        1. There is air there, but it is getting trapped in a separated vortex bubble which means that it heats up. Brakes and bearings in modern vehicles were design with the intent of disrupted air moving through them to cool them. With engine heat also trapping in that separated vortex bubble you develop heating and wear issues. The ambient temperature stays much higher than the designs were intended to handle which would require a secondary cooling method to extract the heat.

        If it was just a simple case of adding fairings to trucks this would have been done years ago by truckers to save money. The fact that hasn’t happened should be an indication that there are secondary issues that a quick blog post cannot explain (or the author lacks the knowledge need to bridge that gap).

        2. Those skits are interesting, but as a truck driver I have a lot of concerns. Going over humps, snow build up, and how to I inspect the vehicle, put on tire chains, change tires, etc… Add hinges? they need to put up with the wear and tear of driving, road salt, freezing, baking, etc… again, it isn’t something simple. If they are broken do I have to get them fixed to be legal to drive? What is a legal condition that they can be in? Do I lose more time and money maintaining them rather than just not using them at all?

        3.Long haul would benefit more by switching to train carried corridors (ala RoadRailers type technology) and having the trucks be short haul only. That option will only become viable however when we can slow down the rate of supply needs, but that would become too ‘inconvenient’. Trucks took over for trains on the grounds of speed and price (trains were heavily regulated). Today that could be changed, but the modern world isn’t ready for that yet.

        • Bob_Wallace

          #3. The best way to reduce our CO2 levels from freight hauling would be to electrify rail and, as you suggest, use trucks for ‘the last few miles’. (That’s not job-friendly for truckers.)

          We’ll be freeing up a lot of rail space as we reduce our use of oil and coal.

          Russia electrified the Trans Siberian Railway. It’s long enough to cross the US twice. If Russia can do it you know we can.

        • 1. I just don’t buy it. There is plenty of air movement anywhere outside a vehicle on the road. If you can’t cool your bearings, you’re doing something really wrong. “If it was just a simple case…” This argument is used all the time. There are lots of things I’d like to have that nobody makes. There are an infinite number of products that simply can’t be had.

          2. Fine, don’t use them. Inefficiency is tax that I don’t pay.

          3. That kind of infrastructure is the sort of thing that must be commenced 20 years before it’s needed. Unfortunately, few have their eyes that far into the future.

  • BillW

    This seems to be all about the tractor, not the trailer. Also, the article states “video cameras replace the massive mirrors all semi-trucks currently require.” I still see those massive mirrors in the photos, albeit with aerodynamic fairings.

  • driveby

    German designer Colani from years ago:

  • hikerscotty

    wow even the license plate is aerodynamic, this is what the future of transportation looks like

  • Senlac

    Great article, who would think aerodynamics could make such a difference. Put a hybrid engine in it and get a bit more.

  • JimboPalmer

    Is it just me or is this about the tractor, and never really mentions the trailer? I think the Headline Writer never read the article.

    • Omega Centauri

      Yes, I was expecting info on the trailer, which is also important. This tech could be a good start, many trucks pull lots of different trailers, so it is going to be harder to market aero-trailers.

      • Wayne Williamson
        • Omega Centauri

          Its actually more than just the bullet front. Typically the big aerodynamic loss it at the back end, which is where the flow streamline separate (leaving a low presure zone at the backend of the vehicle pulling it backwards). Here is the money quote from the article:

          At the very rear of the trailer unit, a retractable, tapered end section lets airflow leave as cleanly as it arrived, reducing aerodynamic drag

          In the past I heard these refered to as “boat-tails”, and they are supposed to greatly reduce drag. So it is also features added to the trailer.

  • If you can operate a truck-train to bring stuff from Connecticut to California v.v. maybe you need to rethink you prodcution scheme and produce more locally? THAT would save a lot of fuel.
    I really like the low hanging fruit approach though! Nice truck.

    • Just use the train. Would save tons of fuel. Literally tons.

  • José DeSouza

    It sure does make a lot of sense. Now, just imagine if the same concept were also equipped with Siemens trolleytruck technology: Wind and solar power could then help save some more additional diesel fuel. Smart, ain’t it?

  • SirSparks

    Wow! That is a better mpg than my Ford Econovan (E150) which with ladders on top only gives me 12.5 mpg. At least it’s easy on my brain power though; 100 miles = 8 gallons.

    • driveby

      I always wondered why there aren’t ladder covers for those tradies to streamline their ladders..

      Business idea anybody?

      PS: they need to be easy get off and get on.


  • Don’t forget about Jevron’s Paradox. If this technology reduces the cost of tarnsporting goods by truck, more goods will be transported by trucks giving equal emissions and equal oil consumption nation wide. Just saying. What we need is to stop trying to grow our economy. And we need to stop using fossil fuels to transport goods.

    • Chatteris

      Really important point. No good saving a stash of money on petrol and then blowing it on a trip to Bali. How we reinvest the savings is key – more clean tech, education, books – come to mind as some possibilities for an individual or a family. How enlightened companies could approach this would be an interesting discussion.

    • Bob_Wallace

      There’s nothing wrong with growing our economy as long as we do it in sustainable ways.

      We should strive to give everyone a good place to live, quality food, decent clothing and some toys.

      • driveby

        That depends entirely on the definition of ‘growth’ or better what is ‘growing’.

        The current metrics which are being used and assessed to measure growth are dominantly bad for the planet and our health.

        • Bob_Wallace

          Here’s how Princeton defines economic growth…

          “growth in the productive capacity of the economy (and so a growth of national income)”

          I don’t think there is anything wrong with growth or our way of measuring it. Only in some of our inputs.

          • A Real Libertarian

            “I don’t think there is anything wrong with growth or our way of measuring it. Only in some of our inputs.”

            A different Bob had something to say about this a while back.


  • Chatteris

    And you don’t even have to believe in climate change to think it’s a good idea! This is the way to go – produce technology that will save people money as well as saving the planet and they’ll use it, in droves.

    • Bob_Wallace

      It’s how you save the planet. You make cleantech stuff more affordable than dirtytech stuff.

      People do the right thing for personal short term gain.

      • tibi stibi

        which will be the case in most situaties. in the end what you pay is energy. and saving energy is what it is all about.

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