Wheel skirt design...

[19bonestock88]

So, I'm making wheel skirts for my Malibu, and I've come to a part where I've got a question... Right now, I've got the skirt following the wheel arch for the first 135 degrees or so(imagine this as a portion of a semicircle), then curving out and going outside the arch straight back for about 6" and terminating... Underneath the skirt, the body tapers inward near the bottom, leaving about a 2" gap between the bumper cover and the skirt face... Now, this area is open for air to flow from the wheel well out the back of the skirt, but is this good, or would I be better off to taper the skirt back into the body of the car, and risk airflow separation due to the somewhat sharp curve?


The top of the rear part(blending from semicircle to square sticking out) touches the car, but the bottom part doesn't...

[mcrews]

you really need to post pics

[kach22i]

I can visualize this, but yes a sketch and or photo is worth a thousand words.


Google image search: vent wheel well car


Superhachi.com - Downforce Basics

The wheel wells are another area where an undesired pressure differential can develop. Air flowing beneath the car stagnates on the tires, creating an area of high pressure. This effect is compounded by the brake cooling ducts that many teams use, which force even more air into the wheel wells. All of this air is also heated by the brakes, creating the same buoyant forces as in the engine bay. This high pressure area also exerts a drag force on the car. For this reason, many race cars and high performance road cars also incorporate

In my opinion, you don't have a race car with extreme forces, so go ahead and pull the trailing edge back in flush with the body.

Just a guess, but your venting needs are not that great.

The examples I've all found deal with the front wheels which turn and allow air in.

At the rear I'm guessing this sudden influx of air pressure does not happen because the wheels remain parallel to the direction of travel.

Again I have no data or experience to share, just using my imagination to reverse engineer what I have seen and read.

EDIT:

I found an example of a rear wheel vent, but once again it is a very wide tire in a race car which could trap a lot of pressure in the wheel well.

An Introduction To Racecar Aerodynamics & How Aero Can Improve Your Laptimes - The Tuners Group

It is important of course to use properly designed aero parts that are tested and proven to work - parts that create additional downforce without creating excessive additional drag.

Yea, just thinking the open trailing edge on your rear wheel skirts will create more drag than they resolve via lowering or internal pressure.

[freebeard]

https://www.google.com/imgres?imgurl...=8#h=440&w=586

Mercury turnpike cruiser skirts go to 90° and then a straight line. See also 'bubble skirts'.

[kach22i]

Cool if he can extend to the rear end with similar smoothness.

[mcrews]

Originally Posted by freebeard

https://www.google.com/imgres?imgurl...=8#h=440&w=586

Mercury turnpike cruiser skirts go to 90° and then a straight line. See also 'bubble skirts'.

that is not a skirt!!! THAT is a work of art!!! nice find!

[19bonestock88]

This is where I'm at with my skirts... I ran out of fasteners or Velcro and so, the bottom edge of the skirt sticks out from the car... the first test run was aborted when the trailing edge of my drivers side skirt began flapping in the breeze, so I assume that airflow isn't quite right...

[mcrews]

I would curve the trialing edge up to the fender, gently.

Also, I experienced a vibrating at higher speeds and had to run a thin piece of metal along the bottom edge.
THe material we use is just too flimsy NOT to vibrate.
take alook at my skirts.....
http://ecomodder.com/forum/showthrea...ast-16970.html


see post #37 to see the metal bar I installed.

[aerohead]

This flush skirt would be a nice way to go,if you could.It would require extension and some rocker panel work

[freebeard]

mcrews — It's merely a Mercury skirt on a year-earlier Ford, with the stock chrome edging removed. Pretty standard in rockabilly circles.

Go around signage shops and see if you can get a partial (or used!) sheet of PolyMetal. The piece I got was 2x3ft or so for $20-25.



It's a stiff as 5/8" plywood. Follow the horizontal cut line for the bumper on top and box out the bottom like on that Miata. aerohead's example terminates in an angled skeg. That could in turn be an outer fence on a diffuser.