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Old 02-25-2011, 11:19 AM   #136 (permalink)
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Originally Posted by t vago View Post
I saw some interesting sights during this last winter snowstorm a few days ago. People around here generally don't brush off more than the bare minimum of snow from their cars, and of course they like to drive on the interstate with all of this snow blowing off.

On quite a few of these cars, I happened to see snow aerodynamically shape itself to the roofs of these cars, such that the roof was effectively raised a few inches. That makes me think that for maximum gain, maybe the leading edge of this template ought to be matched to the windsheild of a given vehicle, and then aero extensions ought to be built to match the template (even if it raises the roof a bit).

Then again, that may drop C(d) at the expense of increased frontal area. Just a thought...
There has been work done on this, and it is in Hucho's book. You can drop the Cd of the vehicle by raising and rounding the roof of an automobile by up to several inches. However, when you take the increased frontal area into account, the CdA actually increases steadily, meaning there is no real gain to be had here as long as the vehicle had attached flow to begin with.
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