Outer Limits 4x4 Board

gday all

I have a roof top tent on a 3/4 length rack and when on the free way you can really feel the drag from it being on there aswel as higher fuel comsumption.
So i was thinking about making like a flow over ramp for the air like you see on trucks on top of the cab. Has anyone done this?? pics, advice, ideas would be awsome.

cheers

Get 1 roof rack, place as far forward as necc.
Attach aluminum plate to rack to add support at front of plate and attach the trailing end to top of tent section.

Not sure what would be the best way to go about making it removable to access your tent though.

something to think about......

most of the drag is from how the air forms BEHIND the vechile. the smoother you can make the airflow jion back up at the rear the better.

yeah doesnt matter about taking it off, the tent folds out over the back, the front space is not used at all. Now i have never thought about the air at the rear... spose its just when the tent is on its worse as its just about 1 foot of flat area

tweak'e wrote:something to think about......

most of the drag is from how the air forms BEHIND the vechile. the smoother you can make the airflow jion back up at the rear the better.

whilst some of the drag is caused by the vacume behind the vehicle, im not sure about saying most of the drag.

trucks focus on reducing the drag at thew front of the vehicle whilst the rear is a slab, if the rear was so important they would have a fold over shape on the rear to improve it I would think.

Im not an expert in any way shape or form, but every commercial attempt at reducing drag on 'loads' is done at the front.

however yes ther is drag at every point top, sides, back etc etc.

Apart from a buffer on the front i would think its just a part of life.

most of the drag is certain a the rear. have a look at all the aerodynamic shaped vehicles/planes etc. typically big at the front and then tapering to a point at the rear. its the turbulence which causes the drag which is all in how the air flow meats up at the rear of the vehicle.
trucks don't taper the rear as they need the room for cargo which pays the bills. its a case of they can't do anything to the rear, they can only do the front.

you can make a front bit to make the air flow over the top, just got to get the shape and height roughly right so the air flows over the top and joins nicely when it comes back down and joins the rest of the air flow. you could also fit a tail behind the tent. that helps the airflow join up better wit the vehicles airflow.
also if possible have rounded corners rather than square on anything exposed to the wind.

yes mate i hear your pain, i got a full length roof top tent and without a doubt she pulls you back and drinks the fuel. Add to this mine mounted on rhino bars mounted ontop of a heavy duty arb bar! so its high. I put the arb wind deflector in the rack which is hard to measure the effect. You do see occassionally on such a rack the luggage or tent sat slightly back and perspex or alloy sheet attached to the front of the rack but simply twice as high. I can only see it helping but will just look di#ky if its on there when tent not on. If always on then no probs.

bingham

well yeah that was the plan just something to help at the front of it. Anyone got any pics?or ideas with like material size? do i make it higher than the top of the tent ?

cheers

most aerodynamic shapeis a tear drop
somethin to think about

i thought the egg was the most aerodynamic shape?

could be thought i read it was tear shape but possibly egg similar shape
http://www.wonderquest.com/beer-streamline-size.htm

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