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Old 11-10-2022, 06:35 PM   #5 (permalink)
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Originally Posted by AEOLUS View Post
What about this, how would you read this 2 graphs?
Why Cd has negativ and positive numbers at first graph?

These are for simplistic, primitive, prismatic test models, of which no current productions share any similarity.
On the upper table, for 0.09%, and 0.18% aft-body lengths, you're witnessing an initial drag reduction, then introduction of increasing vortex drag, until vortex-burst occurs, and wake takes on a squareback wake.
The lower tables show all the test permutations of Giugiaro's (sp?) original Golf of 1975. Again, drag drops, then vortex drag builds until 'burst.'
Lesson: a 'large' high-pressure wake is preferred to a 'small' low-pressure wake.
Vortex-drag is BAD!!!!!!!!!!!!!!!!! Really bad!
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