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Sign on trailer gate and wind drag?

Discussion in 'Trucks and Trailers' started by walker-talker, Mar 16, 2005.

  1. walker-talker

    walker-talker LawnSite Platinum Member
    from Midwest
    Posts: 4,771

    Drop gate on trailer measures 4ft x 6.25ft. The sign that I want to mount measures approx. 3.5ft X 5.5ft. Do you think I will expierence a considerable amount of wind drag and a decrease in gas mileage?

    For the most part I won't be on the highway. Maybe one day a week and only approx 4 miles. Most of the driving will be 35mph to 40mph.

    What do you think?

  2. marko

    marko LawnSite Senior Member
    Posts: 963

    Try a piece of plywood and check it out. I would think you would have no problems.
  3. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,197

    I was thinking the same thing, so I put the sign on the back side of 2x2ft blower cage which is on the front part of the trailer. I had a cardboard one on for a while and it nearly tore it up from wind.
  4. Precision

    Precision LawnSite Silver Member
    Posts: 2,995

    I have to tell you that it will make a huge difference.

    I drove with a trailer with no gate roughly the same weight as mine for 100 miles and got 13.5 miles per gallon

    Then I drove (same truck and load) with my 5' high gate (with expand a metal) and got 10.5 miles per gallon over roughly the same 100 miles. So my drag was increased that much with a perforated substance. I can only imagine what a solid object would do.

    The plywood idea is a good one.
  5. Guthrie&Co

    Guthrie&Co LawnSite Senior Member
    from nc
    Posts: 784

    here a trick to help you get an idea. ride down the road at 50 mph and put your hand out of the window. turn it so the flat side is facing forward. how much drag to you feel with that? now just imagine what your sign will do. my point being is that it will be alot of wind resistance
  6. beransfixitinc

    beransfixitinc LawnSite Senior Member
    Posts: 592

    Speaking of wind drag.. why aren't enclosed trailers built with a sloped roof, so as to provide downforce on the trailer at highway speed? It would seem that even a slight slope from front to back would give more control on the trailer.
  7. LonniesLawns

    LonniesLawns LawnSite Senior Member
    from KS
    Posts: 317

    as far as drag -- a perforated metal gate has about about hte same drag as a solid piece of metal back there.
  8. drmiller100

    drmiller100 LawnSite Senior Member
    Posts: 562

    because you want to minimize the tongue lifting affect due to wind as much as possible.
    trailers start to whip when there is not enough tongue weight.

    also, if you look into aero of it all, the rear of the trailer determines how much drag there is. if you look at missles or air planes or whatever or wings they tend to have the widest part forward, then taper to minimize drag.
  9. Guthrie&Co

    Guthrie&Co LawnSite Senior Member
    from nc
    Posts: 784

    thats is about the dumbest thing i have ever heard. the surface area between the 2 are worlds apart.
  10. lpwhandyman

    lpwhandyman LawnSite Member
    Posts: 197

    I have a sign on the back of my trailer.....yes it does have a little drag....but I only notice it when the trailer is empty and I'm on the highway doing max speed. When it has the mower on it, I can't tell a difference. I'm sure it does cut down on the mileage a bit, but I considered it worth the extra advertising that I was getting. Either way, with a full size pickup and v10, I never did like to discuss gas mileage. All I know is I'm raising prices across the board this year, because $60 at the pump is a little much.

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