ORIGINAL: Toad

Most airfoils become "efficient" at very slow airspeeds. This simply means they get laminar flow and begin to create "lift". The amount of lift created depends on the airfoil shape, the angle of attack, and the speed of the relative wind. Most "Spoilers" on the backs of cars are just that. They spoil the flow of air over the top of the back of the car, creating vertices that actually slow the vehicle down due to increased drag. Even though they look like they "push" the air upwards, (which would create a downward force), they really don't do that at all. The Cervini duck tail looks nice, but it actually slows the car down at higher speeds due to the vertical vertices rolling off the back of the car.

In order to create a downward force, you need an airfoilthat creates lift in a downward vector. Basically an upside down wing. The wing that Roush is using in these photos is a true wing. It creates the downward forces without creating drag due to vertices or turbulence. Any time you create lift you also create a small amount of drag, but this is what is known as "induced drag" and is not related to the drag coming off the back of the car. Roush's wing is therfore much more effective at creating the desired downward force, and at the same time creates much less "parasitic drag", the bad kind that the Cervini wing makes.

ORIGINAL: pascal


Thanks for the lesson in physics son butWe don't need down force around town or at civilized speed on the highways.
Having said that, I completly agree with you on the fact that the wing on that Roush is a true one (adjustable and all) and my duck tail is for looks.
But I went for looks with my Stang, since I'm not racing it.