Quote:
Originally Posted by aerohead
*The vehicle is attacking the air mass in front of it and this onset flow is impinging upon the air captured within the pitot and connecting tubing to create the dynamic head.
* While it is true that the the onset flow creates the stagnation pressure at nose and windscreen,it is the pressure differential between the forward stagnation point,and the base pressure of the wake which creates the 'force' the vehicle must overcome.
* The bubble ( which is barely distinguishable over the windshield) can be thought of as a solid structure as far as the air is concerned.
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* With respect to the 1999 GM PNGV Precept,the 'features-drag' which included wipers,wheel covers,mirrors,door handles,and cut lines added a total 0.007 to the Cd.The wiper drag was zero.
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As far as the air is concerned the bubble may be a solid structure, but that doesn't mean it's shaped optimally. Following your reasoning, windshield and hood angle doesn't matter at all, because the air will always form a bubble.
Like I was saying before, most people think of raindrops as being "teardrop" shaped but the air hitting them has no reason to shape them into nice teardrops.
http://ga.water.usgs.gov/edu/raindropshape.html