Quote:
Originally Posted by bnmorgan
ok then, the original question? why is our cD so "high" for what would, on the surface, appear to be a fairly good aero design?
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What you'll need to do,is find out where tangent angles of 22-degrees occur for the roofline,body sides and fenders.This is where the flow must separate and the base pressure must be that of the point of separation.
If the body were more gently curved,as with the Audi TT,the flow would remain attached to the 'end' of the car and separation there would produce a higher base pressure ( lower delta-P ) and drag would necessarily be lower.
It's all about pressure differentials.