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Old 02-09-2013, 05:02 PM   #37 (permalink)
aerohead
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reverse/ellipsoid

Quote:
Originally Posted by freebeard View Post
There's a Delete button too. Just sayin'.

And thanks for that video. I liked the real-world examples of things we would get simulations of today.



I get this in general, but:
  • What's a 'reverse template'? Why can't you see out of it?
  • What's an 'ellipsoid'. Is that like a Dymaxion shape?
*Fachsenfeld wind tunnel tested a L/D=6 streamlined body of revolution,both 'forwards' and in 'reverse.'
*The drag was 22% higher when reversed,owing to the wake,although if wheels were added,as a 'car',the drag would only be 14.66% higher(Cd 0.136 vs 0.12) than the 'Template' (estimating)
The hitch would be that the windscreen inclination would be so extreme that you'd have no forward vision,only a reflection of the inside of he cabin.
*The ellipsoid family are a series of bodies of revolution which are based on ellipses of varying fineness ratios.They are 'double-ended,like a lozenge,and would also pose a serious challenge to outward visibility.
From Hoerner and Hucho's drag measurements,the ellipsoid of minimum drag has an L/D= 2.5.As a road vehicle it would be L/H= 5 with Cd 0.11 in ground proximity,without wheels,according to R.Barth's research.Dymaxion Car is asymmetrical longitudinally,more like an airship than an ellipsoid.
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