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Old 07-24-2008, 06:27 PM   #25 (permalink)
TimMullen
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Quote:
Originally Posted by jhnmdahl View Post
The point of lowest pressure is under the car where the velocity is highest, not at the diffuser. The downforce is created by the relatively low pressure of the air under the car, and the diffuser prevents the air from becoming turbulent while it decelerates, or "stalling", which would reduce the downforce created under the car.

It does work essentially the same as an airplane wing, where the lift comes substantially from the middle/thickest part of the wing, and not from the trailing edge...

John
Yes and No...
The diffuser gives a larger "volume" for the air to expand into. Expanding air drops in pressure. The air is expanding in the diffuser area and that's where the down force is being generated. The smooth under body is mostly for the decrease in drag. Any down force generated because of the flat under body is because of the shape of the top of the car instead.

The air expanding up to fill the area behind the car - along with the turbulent air spilling over the rear lip spoiler combine to decrease drag (and in the case of the spoiler, reduce generated lift).


Quote:
Originally Posted by Pestodude View Post
Sorry, I misstated my meaning. No the Elise doesn't have "lift" but it doesn't have much downforce (compared to the Exige with a wing). The Ferraris have far more downforce with no wing than the Exige with a wing.
I'm willing that the Ferrari has a lot more drag to go with that extra down force. But the Ferrari also has a lot more power to overcome the additional drag. There is no free lunch.
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