Forum Discussion

Wo_ody's avatar
Wo_ody
Explorer
Jun 14, 2013

Roof splitter...better front end aerodynamics

Big beliver here of DIY aerodynamics.

The "pocket" in-between your TRUCK cab and camper cab-over is a huge source of drag and wind noise. Its like towing a parachute.

A roof "splitter" will lower drag and wind buffeting considerably and its easy to make. The idea is to create an inverted "V" shaped appliance which fills the "pocket" between your TRUCK cab roof and camper cab-over.

Cut a 10mm x 4' x 8' sheet of Coroplast corrugated plastic or a 1/8" x 4' x 8 sheet of FRP Panolam (Lowes) to a triangle shape. The base width equals the width of your camper...lets say 80". The point of the triangle extends from the front vertical camper wall forward to the leading edge of the TRUCK cab roof. Then semi-rigid polyethylene foam...such as a pool noodle...is attached to all 3 legs of the triangle. Attach a layer of foam above and below the sheet triangle so it sandwiches the perimeter. ***NOT AN ADVERTISEMENT, JUST AN EXAMPLE*** Sheet polyethylene could also be used and can be located from a supply house such as Foam N' More http://www.foamforyou.com/

The "splitter" is set on top of the TRUCK cab roof and the camper is lowered. The foam will compress to the shape of the roof and the bottom of the camper cab-over. The idea is to make the polyethylene foam thick enough so the "splitter" will stay in place by compression fit.

In my opinion, the reduction of wind buffeting alone is worth the cost.
Truck Campers
  • jimh406's avatar
    jimh406
    Explorer III
    Jun 14, 2013
    Pics would help. But, this got me thinking. What if the splitter was attached to the roof with sheet magnets similar to what is used on signs or as motorcycle tank bibs for something stronger. The foam wouldn't have to go all of the way to the top of the roof. What if you took a noodle and affixed magnets to it or on a cover for the noodle. It would be completely adjustable, lightweight and easily storable ... hmm. What if magnets were attached to molding similar to what is used in bathrooms that's flexible...hmm2.
  • Reddog1's avatar
    Reddog1
    Explorer II
    Jun 14, 2013
    I'm thinking you will rub the paint off the cab of your truck, and/or the underside of your TC cab over.

    This concept has been around at least since the 70's. A very common TC add on. Back then, a cushion was inserted between the cab and cab over, then aired up. As I recall, 6 psi. Some were simply made of foam. Put the foam on the roof, then lower the TC. I have had both types.

    These devices usually wore the paint off the cab of the truck. Someone then come up with a plastic film you put on the roof to protect the paint. That only left the paint on the underside of the TC cab over to rub off.

    Personally, I never found enough benefit to continue using them. Considering you seldom, if ever see them any longer suggest a lot of people see any real benifit.

    Wayne
  • jimh406's avatar
    jimh406
    Explorer III
    Jun 14, 2013
    You could put the clear bra material on the camper as well. I don't think it needs to touch though which is why I was thinking magnets for my variation of the idea.
  • bcbigfoot's avatar
    bcbigfoot
    Explorer
    Jun 14, 2013
    Reddog1 wrote:
    I'm thinking you will rub the paint off the cab of your truck, and/or the underside of your TC cab over.

    This concept has been around at least since the 70's. A very common TC add on. Back then, a cushion was inserted between the cab and cab over, then aired up. As I recall, 6 psi. Some were simply made of foam. Put the foam on the roof, then lower the TC. I have had both types.

    These devices usually wore the paint off the cab of the truck. Someone then come up with a plastic film you put on the roof to protect the paint. That only left the paint on the underside of the TC cab over to rub off.

    Personally, I never found enough benefit to continue using them. Considering you seldom, if ever see them any longer suggest a lot of people see any real benifit.

    Wayne




    I feel discussion of aerodynamics pertaining to truck campers is long overdue, hopefully some really good ideas can come to light.

    The 70's was a different world, I recall 18 cent per gal diesel in California, most trucks were undersized for their loads, didn't have enough hp to get over 55 mph and were dangerous if you did. With new technology there is many things that can be done today that were just pipe dreams in the 70's.
  • Jaxom's avatar
    Jaxom
    Explorer
    Jun 14, 2013
    Magnets? Aren't most camper wood or aluminum frame with aluminum skin? Or fiberglass construction?
  • bcbigfoot's avatar
    bcbigfoot
    Explorer
    Jun 14, 2013
    Jaxom wrote:
    Magnets? Aren't most camper wood or aluminum frame with aluminum skin? Or fiberglass construction?


    You are correct however I believe jim425 is referring to the magnet going on the truck roof and the clear protective film to be applied to TC.

    I could see this working. I have kicked around the idea of applying stick on Velcro to both the camper and truck roof and then cutting a tarp, or a thin rubber type material (with Velcro sewn in) that would bridge the gap between truck and camper.
  • jimh406's avatar
    jimh406
    Explorer III
    Jun 14, 2013
    Yeah, I was talking about magnets to go on the truck roof. I also ride motorcycles, so I'm familiar with sheets of magnets for tank bibs etc. I also took a look and apparently there is a lot of sheet magnet material available on ebay, etc to make bumper stickers/craft projects for pretty cheap prices.
  • Wo_ody's avatar
    Wo_ody
    Explorer
    Jun 14, 2013
    Magnets give me concern as they are hard enough to scratch paint. Be sure to use a "slip sheet" under them. Also, magnets can distort metallic paint finishes.

    Polyurethane foam (pool noodle) is a closed cell foam which is reasonably soft and flexible. Anything rubbing on paint long enough could eventually damage the paint. However today's clear coat auto finishes and camper baked-on finished aluminum or FRP gelcoats are far more durable than finishes were 30-40 years ago. If there is a concern, a simple "slip sheet" of 6 mil painters plastic poly between magnets and finishes should protect.

    The intent is to not allow ANY air under or over the splitter. It all gets deflected to the sides. The beauty of the polyurethane foam is it will compress to form around any curves of the two surfaces. I would also put a few VGs on the TC vertical sidewall right behind where the splitter butts into the TC front vertical wall as the air transitions off the splitter.

    There are many ways to fabricate a splitter. How you do it is not as important as trying anything to eliminate the drag bucket created by the TC mating to the pick-up truck.
  • Reddog1's avatar
    Reddog1
    Explorer II
    Jun 14, 2013
    bcbigfoot wrote:
    Reddog1 wrote:
    I'm thinking you will rub the paint off the cab of your truck, and/or the underside of your TC cab over.

    This concept has been around at least since the 70's. A very common TC add on. Back then, a cushion was inserted between the cab and cab over, then aired up. As I recall, 6 psi. Some were simply made of foam. Put the foam on the roof, then lower the TC. I have had both types.

    These devices usually wore the paint off the cab of the truck. Someone then come up with a plastic film you put on the roof to protect the paint. That only left the paint on the underside of the TC cab over to rub off.

    Personally, I never found enough benefit to continue using them. Considering you seldom, if ever see them any longer suggest a lot of people see any real benifit.

    Wayne




    I feel discussion of aerodynamics pertaining to truck campers is long overdue, hopefully some really good ideas can come to light.


    Actually they have been ongoing on RV.NET for years, so I really do not understand your thinking these discussions were " long overdue".

    Probably once a year, someone discovers the airtabs. The discussion starts all over again how they are the greatest thing to ever hit the RVs. Some people spend lots of money based on the hype. Very few post their disappointment in the money spent and lack of performance on the airfoils, but some do.


    bcbigfoot wrote:
    The 70's was a different world, I recall 18 cent per gal diesel in California, most trucks were undersized for their loads, didn't have enough hp to get over 55 mph and were dangerous if you did. With new technology there is many things that can be done today that were just pipe dreams in the 70's.

    I can't see how this possibly negates my experience. You can trade the cab/TC fillers with tabs or something else. But I question any serious change in the aerodynamics.

    My post was intended to be informative, not negative. Some wise person supposedly said; "Those that do not study history, are doomed to repeat it."

    Wayne
  • 6pac's avatar
    6pac
    Explorer
    Jun 14, 2013
    Sleepy developed a similar device that he posted here I think he called it an airfoil. You may want to look that up . Just a point of intrest.

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