Quote:
Originally Posted by aerohead
*I don't recommend anything other than the 'Template.'
*I offered the plan view 4:1 section profile only as an illustration of something 'different' which has been used to good effect.
*NASA's Ford Econoline boat tail lowered the drag from Cd 0.47,to 0.238.That's really good,but they left 50% of the drag remaining on the van.
*In fluid mechanics the shape defines the drag.Size makes no difference as long as Reynolds numbers are equal.
*We do know what the rules are:
*1 you can base a design around the 'Template' aft-body contour for low drag in a vehicle you can see out of.
*2 you can base a vehicle on a 'Reverse-Template' and achieve drag within 15% of the 'Template',but you won't be able to see out of it.
*3 you can base a vehicle on an ellipsoid and achieve identical drag as the 'Template' but you won't be able to see out of it,park it in a garage,go over a hump,around a corner,etc..
*4 you can base a vehicle on arbitrary legal length requirements and do your best to optimize for that length only,knowing you'll never actually achieve the lowest drag.
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For the rules, I was refering more so to the fluid dynamics equations, but those 4 points above do help clear some things up for me,
I think I'm stuck with #4 and trying to see what I can draw from 1,2 &3 to optimize that position.
Thanks.