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Old 04-09-2008, 09:53 PM   #20 (permalink)
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1999 Saturn SW2 - '99 Saturn SW2 Wagon
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tasdrouille -

Originally Posted by tasdrouille View Post
The rougher the underside of the vehicule, the more benefit there will be from a reduction in ride height. On the other hand, if the underside of the vehicule is a very good aerodynamic shape, increasing ride height will reduce the drag coefficient. If I remember right, an airfoil can have a Cd of roughly .05 up high in the air. Bring this airfoil in ground proximity and the Cd now jumps to .1 or the like due to ground effect. There is a reference of this in Hucho's book. The aptera is also a good example of this IMHO.

Generally, your average car will benefit from ride height reduction.

The frontal area argument is not really relevant. Say you drop 2 inches in a 22 square feet car, the net result is a reduction in frontal area of roughly 0.75%.
I'm gonna stick with this definition as a general rule-of-thumb.

As far as I am concerned the Aptera is a "small-plane" body shape with fixed wheels. Since it doesn't fly (yet), there isn't any reason to make them retractable, .

We really really really really need open source wind tunnel software.

Orrrrrrrr, maybe DIY coin-op car washes could be adapted for wind tunnel testing. Get some big fans and have a "dirty mist" or "misty mud" mode on the car wash control dial. Use the dirty mist mode to "find" the bad aero spots on the car. Wash the car off (more coin for the car wash owner), make another aero mod, and repeat. Pay as you go in 1:1 scale !!!!!


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