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Old Jun 08, 2016, 01:15 PM
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Wings for RC Cars

I'm building "wings" for 1/5th scale road racing cars. Car bodies are mostly based on touring car series around the world - 4 door BMW, Audi, Mercedes, etc.

I say wings, but really they are large spoilers, a concave shape flat plate ( see attached picture ). This is pretty standard in the sport right now, but I'm wondering if an inverted airfoil shape wing would work better.

My background is RC Soaring, DLG, Slope and F3J, so I have a fair idea how airfoils work at those levels - no idea if they are worthy for the RC cars.

By the rules, chord is limited to 60mm ( about 2.3" ) and span is about 255mm ( 10" ). I would estimate top speed around 60 mph on the straights.

So - any educated suggestions if this is a worthy idea? Can this be evaluated in XFoil or any other analysis program?

Thanks .... Bruce
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Old Jun 08, 2016, 01:30 PM
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These wings operate at a fixed angle of attack, so short of structural considerations there's no aerodynamic advantage into having a greater thickness on them. No need for a round leading edge delaying the stall.
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Old Jun 08, 2016, 02:26 PM
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Depending on how high and aft you place the wing--the rear download can also unload the front and the car will understeer badly
no free lunches ----------------
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Old Jun 08, 2016, 04:20 PM
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Quote:
Originally Posted by richard hanson View Post
Depending on how high and aft you place the wing--the rear download can also unload the front and the car will understeer badly
no free lunches ----------------
No free lunch? How about if it equals downforce with reduced drag?

Bruce
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Old Jun 08, 2016, 07:27 PM
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That sounds like a good trick
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Old Jun 08, 2016, 07:31 PM
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The only increased net downforce with less drag --was a vacuum cleaner car by Jim Hall.
But hey - give it a shot .
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Old Jun 08, 2016, 10:21 PM
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Because the wing is so close to the body there is interference to the flow that XFoil canít deal with.

IMO, the wing on RC Touring cars are more like a slotted flap than a pure spoiler or wing.

I also agree with Brando about the thickness.
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Old Jun 09, 2016, 07:22 AM
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Light, rigid, adjustable.

The three most important factors
Airfoil?
A simple plate with end plates
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Old Jun 13, 2016, 08:52 AM
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This would help:
http://www.mh-aerotools.de/airfoils/javafoil.htm
and then select "Ground effect" for more details.
http://www.mh-aerotools.de/airfoils/jf_wig.htm

/Bernd
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Old Jun 13, 2016, 11:38 AM
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The setups for aircraft is not the same as a car .
Sans an adjustable plate setup - a wing on a car is at best, a SWAG
depending on the track - the best downforce arrangement, front to rear varies
Why ?
turns require different loading to produce best controllability.
In the scandahoovian countries - ,ice racing with cars requires a different traction setup than a car on dry asphalt.
The front to rear loadings -either aerodynamic downforce or weight distribution is very important
I once had a AH 100 roadster with a small block Chev up front - weight distribution 45/55.
good for straight line but oversteer with power was a real problem
I don't think a wing would have fixed it.
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Old Jun 13, 2016, 01:00 PM
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Shame about the restricted dimensions.

These types would probably be more effective at model size --

https://www.google.co.uk/search?q=sp...HUyxCagQsAQIGw


At such a small size, in my opinion the 'official size wing' would be more like for looks than for aerodynamic functionality.

Ray.
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Old Jun 13, 2016, 03:28 PM
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The roundy rounds travel much more slowly than the road cars - hence the tent like proportions of the wings
Way back when - some stock car bodies which looked streamlined, ran out of traction due to lift from the sloping top rear of the body and the air pressure build up under the floor
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Old Jun 13, 2016, 04:48 PM
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Another major problem with wings on a car is that they provide the most downforce when it's needed less, in the fast straights. A wing large enough to provide good downforce in a turn will cause a lot of drag in the fast sections. So much so that F1 designers go to some lengths to allow the wing to flex to a lower drag profile as it gets more and more loaded. This in turn means that rules were made that a part cannot deflect more than so under a specific load.
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Old Jul 18, 2016, 10:15 PM
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So maybe a flexible wing like this?
http://www.rcgroups.com/forums/showthread.php?t=2699661
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