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Old 03-21-2012, 04:22 AM   #6 (permalink)
t vago
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Quote:
Originally Posted by KamperBob View Post
I like it. Version 3 eliminates almost all concavities. Very close to a concept in geometry called convex hull. Rock on!
Heh. It seems like it'd be simple to fabricate, too. At least, compared to version 2. The ribs are going to be fun to cut out, but laying the skin ought to be a lot easier.

Quote:
Originally Posted by drmiller100 View Post
what is the "frontal" area at the back of the cap which is flat for versions 2 and versions 3?
It's calculated out to be about 4.8 square feet for the version 3 model, and about 2.1 square feet for version 2.

Quote:
Originally Posted by drmiller100 View Post
I actually like version 2 better. My opinion - the minor vortexes created around the square edges are insignificant compared to the turbulence at the back of the car once the body ends.
The streamlines for version 2 don't work so well. Currently, some of the air from the top is actually going over the sides of the cap, which is causing some of the vortex interference I'm seeing. The vortex effects cause my wake to be approximately twice as wide as my truck, which is not insignificant.

I've played around a bit with the design, and come up with the suggestion that it's not necessary to have the cap be a perfect arch at the rear. It can approach, say, 80% of an arch, still be round enough, still allow a maximum flow angle of no more than 15 degrees, and narrow the rear face area to around 3.5 square feet (correction from last night).

Last edited by t vago; 03-21-2012 at 02:37 PM.. Reason: corrected estimated rear face area - again! Don't drink and compute, folks.
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