Wheel skirts for the aerodynamically minded

[Daox]

Ahhh your a picky lot of chaps! Thankfully I'm at home now and youtube's registration is short and painless.

http://www.youtube.com/watch?v=gb-S5gIKSe4

[MetroMPG]

Ah! Neat.

Comments: I have read that it generally does not pay to increase frontal area just in order to achieve the ideal shape. (Although I read that in the context of roof design.)

I mention that because it looks like the leading edge of the skirt would have more of a gap between it and the tire/wheel than the trailing edge. Just minimizing the gap, and keeping transitions as smooth as possible with that constraint, might be the best approach.

[Daox]

I guess I was thinking of using this versus the normal covers I've seen which are more of a symetrical arc if you can imagine that. The buldging out is needed to clear the wheel. So, the cover would only extend as far out as need be, definitly no farther.

[Daox]

Any other ideas or comments?

Again, this shape would take place only because it needs to, not where it wouldn't need to. For instance on most cars toward the bottom of the body they tend to taper inward. This happens on both my Paseo and Matrix. Now, the skirt will need to buldge around the wheel instead of staying flat against the outside face of the wheel well. In this instance would it not be more aerodynamic to have the tear drop shape?

Also, how does the gap between the skirt and wheel/tire effect things other than just needing clearance for suspension movement?

[MetroMPG]

I think the goal should be minimizing the gap between the tire & the skirt. I think by definition, that means you may not be able to build in a tear drop shape.

On my car, I intentionally avoided rounding the skirt back towards the bumper cover at the aft end of the arch. Instead, it joins the rear mud flap. My thinking there was clean separation at the end of the skirt was best.

When I tested the skirts on the Camry hybrid & Corolla, I used the rear mud flap in both cases for aft fastening (OK, duct tape) and then I also "faired" from that point aft to the bumper cover (cardboard). That additional fairing in addition to the skirts provided the best results on both cars.