Quote:
Originally Posted by aardvarcus
Aerohead,
I am away from my copy of Hucho at the moment, but I remember the picture you are referencing. I am assuming based on your reply you think this may work.
Freebeard,
The reason for the triangle versus the curve or bell, is that I am trying to reuse the rather large (60" x 22") existing window in each side, which does not curve significantly from front to back, in order to save time and effort. Thus the concept of just angling the side at a fixed angle, verses a curve.
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Walter Lay achieved Cd 0.12 with his models at the University of Michigan using simple hard angles. Vortex-drag investigations with the Ahmed body demonstrated good effects using nothing but hard angles on top,sides,and diffuser. And then there's Hucho's bus schematic. My first 50-mpg trailer had hard angles.And the one-wheeler.Scott Funderburk got his Masters in Mechanical Engineering for his hard-angled boat-tail research,working around the General Motors Optimum Boat Tail, at Texas Tech.Scott did progressively softened corner intersections to mitigate attached vortices.NASA never softened anything with their Project Shoebox,and still got to Cd 0.238.
It's certainly within the realm of probability that you'd have success.Perhaps separation with re-attachment,dragging a modest,locked-vortex down the road with you,but the pressure regain from the boat-tail taper would outweigh the small vortex liability.I'll bet you coffee and an apple fritter!