Quote:
Originally Posted by winkosmosis
Sounds like trying to drive a sailboat by setting up a fan behind the sail.
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That's a common reaction, especially among fluid types who have learned over decades that laminar flow is the only way to increase aero efficiency (this explains the persistent interest in LFC despite serious operational deal-breakers). Their gut tells 'em that the added complexity and energy demands of the suction system can't possibly be more efficient than a streamlined body.
The net benefit can be shown by a modified version of the MPG calculator that MetroMPG put up in another thread. Even with the added power for the suction pump and for a design as poor as the one I posted earlier, the modified car consumes less energy at high speed.
A design that doesn't suffer the problems I pointed to will have a lower Cd figure and may require less suction power, too.
Skin friction drag is still there and is as real as ever. This drag can be offset by pressure thrust on the rear of the body at the cost of the suction power. The question becomes which setup is more efficient?
Does this help it feel less like snake-oil?
If not, where does it fall apart? I really am eager to learn where things break down.
-Dave B