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Old 08-05-2017, 01:35 PM   #10 (permalink)
aerohead
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clean vs dirty

Quote:
Originally Posted by EcoCivic View Post
I have heard that a dirty car gets better mileage than a clean car because the dirt creates a rough surface, kind of like a golf ball. But Mythbusters tested that and found thhat a dirty car reduces mileage, but then again they sprayed a half inch thick mud coating on it, which is not at all indicative of a "normal" dirty car, unless you go offroading lol. What do you think, and how big could the difference actually be? Thanks
Aeronautical engineer and creator of the Litestar/Pulse,100-mpg vehicle of the early 1980s claimed Cd 0.18 'clean' ,and Cd 0.20 'dirty'.
It suggests that the vehicle had a laminar body.
Sighard Hoerner,who was with Messerschmitt in WW-II,claimed that the rough,olive drag,flat-primer-like paint on their fighter aircraft made no difference to performance.
Rough,clay,full-scale wind tunnel models appear to generate the same Cd as a production,OEM,lustrous paint-finished model of the same car.
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