Improving aerodynamics

Discussion in 'Tow Vehicles, Hitch & Towing' started by aust, Jan 12, 2018 at 7:19 PM.

  1. aust

    aust New Member

    I tow my Aliner Expedition (~2300 lb) with a Volvo S70 sedan, and while it is a capable enough TV for the job (190hp/199lbft light turbo 5 cylinder is able to just barely keep highway speeds up steep grades) I was hoping for better fuel economy. It gets 27-29mpg hwy on its own and only 17mpg while towing 60-65mph on flats. This jumps up to 23mpg when drafting a big rig. I suspect that a TV with a larger front profile might perform better since pups are so boxy, and ultimately it's a choice between the TV or the pup punching that hole through the air, and TVs tend to be smoother lines. It also struck me that the sedan shape is probably pretty inefficient since it leaves a lot of empty space between the vehicles.

    Has anybody experimented with adding on any kind of fairing to their rig? My understanding is that the main places to focus are 1) between the TV and the trailer, 2) under trailer skirts, and 3) in the rear of the trailer.

    For (3) I see that a product called airtabs exist, and truckers tend to have these rear fairings that look pretty simple to replicate DIY, just 4 flaps that fold into a roughly tapered shape.
    And (2) seems like a poor choice because it costs ground clearance
    But (1) seems particularly interesting since I suspect it would have the most impact on my particular rig. I got thinking how articulating busses have those accordion connectors, think I could do something like that between the back of my car and the front of my trailer?

    And yes, I know 17mpg isn't too bad in the grand scheme of things, but I was hoping that I could get to the 20-25 range by using a somewhat underpowered vehicle.
  2. Byrd_Huntr

    Byrd_Huntr Well-Known Member

    Jan 27, 2013
    I don't have numbers, but when I was towing a TT with my Chev sedan many years ago, I found that I got better mileage when I strapped an inverted Coleman canoe on the roof of the car when towing.
    jumpoff likes this.
  3. SteveP

    SteveP Active Member

    May 21, 2015
    Seems like a V shaped fairing following the lines of the A frame to the trailer body and also covering the top of the propane tank(s) might do some good. You actually used to see these on some of the upper level campers in the 70's. But you have to consider, if they worked why aren't they still available? For the back, a simple deflector wing like they used to put on the old station wagons, should help to break up the low pressure pocket, but I doubt that gas savings would be hardly more than noticeable.

    Then again, cars are more slippery than they were back then so there might actually be some benefit. The only way to know for sure is to try.

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