View Single Post
Old 12-16-2010, 07:06 PM   #31 (permalink)
Master EcoModder
aerohead's Avatar
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,107
Thanks: 19,408
Thanked 6,141 Times in 3,775 Posts

Originally Posted by wyatt View Post
Observations from wind tunnel test pictures would indicate that with a boat tail, one can go to ~15deg, with a virtual boat tail off the back of an average sedan, ~10deg is more of the max. The 10deg number would assume there is nothing turning the air at the beginning. This would explain why small cutouts for windows, lights, etc. have less of an impact when integrated correctly on a steeper angle. I attached a picture of a sedan in a wind tunnel, and it looks like the air wants to exit at ~10deg. A re-build at 10deg may show real gains.
You can go as steep as 22-degrees but you have to be careful how you get there.
You'll notice that the smoke traces make no abrupt changes,but rather gentle curves,beginning with zero-degrees tangent angle at the point of the roofs maximum camber location,and steepening as the flow works its way back.
I'm encouraging members and lurkers to consider 'angles' in the context of their 'position' in the aft-body.
The Aerodynamic Streamlining Template Part-C is based on this premise.All 'angles' must be viewed within a contextual environment.If you haven't seen the template,check it out.Also,in a previous thread there a few hundred additional Flow Images.

  Reply With Quote