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Dorian Gray
Veteran Member
 
Join Date: May 2005
Location: Paris, France
 
2008-06-14, 07:00

Looking great so far, atomicbartbeans.

Quote:
Originally Posted by Banana View Post
I find it somewhat counterintuitive that rear would be more important than front as I always think of air hitting the front hard but leaves a bit of vacuum in the rear area. I'm just not understanding how eddies would drag on the object?
Think of it from a conservation-of-energy point of view. Eddies that are swirling (and continue to swirl for many seconds in the slipstream) required energy to get the air moving. That energy had to come from somewhere, and it comes from your forward motion.

The front of a body moving through the air does indeed push air in front of it, causing drag. But the "bit of vacuum" at the rear sucks you back, in addition to its eddymaking properties, causing more drag than the front. That's why aeroplanes often taper to a point at the rear. A road vehicle has practical limitations on length, so fastbacks are not all the popular. Fastbacks also cause lift at the rear, lightening the weight on the rear wheels and causing less traction, which is obviously undesirable. The Kammback eliminates some of this lift while shortening the vehicle.
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