Quote:
Originally Posted by Otto
Actually, Zedan et al at University of Houston about 30 years ago found ~3.33:1 body of revolution to be best, with point of max thickness at ~44.22% of length. Carmichael et al have published on this, saying essentially the same. Hertel, too. Fast swimming fishes such as tuna are shaped in such proportions-otherwise they don't get breakfast, but are breakfast.
But, since we cannot drive around in fish-like bodies of revolution, and have comparatively crappy vehicle shapes to deal with, how about somebody trying a pie-plate-on-a-pole mod for a motorcycle?
After all, a motorcycle is about the worst shape on the road aerodynamically, so may have the most to gain with the bike running in the wake of the pie plate. Might be handy breaking up the wake turbulence and buffeting behind trucks, too, leaving the bike rider in a relatively calm pocket of air, saving fuel into the bargain.
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The 2.5:1 value comes from DVL,Germany,1945.Above this fineness ratio skin friction works against any reduction in profile drag for a net loss.
The 3.33:1 value is very close to the minimum for 2-dimensional flow around a strut.
The difference between skin friction for a 3.33:1 may be a trade-off for stability as is certainly the case for airships.
The blue-fin tuna has the lowest drag coefficient of the pelagic fishes,it's frontal area occurs at aprox. 33 % of body length as of those of the lowest drag fusiform shark with 2/3rds boat tail.
I just enjoyed a preliminary drive in a half body-of-revolution fish-like body and am not convinced that we can't drive around in them.
With respect to the motorcycle,are they exempt from the laws of fluid mechanics?
And if there was any crosswind present,would the motorcycle not "miss" the wake of the pie-plate.
And if the MC were already in the wake of a truck,would the pie-plate not also be embedded within the turbulence of the truck,with no hope of performing while "submerged" in turbulence?