Quote:
Originally Posted by gumby79
Any open back with sides will have an eddy. Eddy=fuel economy reduction, you don't get to spin the air for free. I'll be it it would be a smaller eddy ,their for a smaller penalty.
Dreem big chisel down to reality
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I think that "Box Cavities" can be made to work.
There was a thread on it a while ago, several articles/PDF's were posted.
Box Cavity for a pick-up truck
http://ecomodder.com/forum/showthrea...uck-26367.html
In that thread above is one of my favorite images discovered by participating this forum.
Automotive Aerodynamics: Drag Area – Size Matters
The VW van tail does not follow the aero-template and is open ended, yet I am told by a forum member familiar with the project that it worked quite well.
EDIT: gumby79, your description is similar to Aeroheads, net positive gain I think?
http://ecomodder.com/forum/showthrea...k-26367-3.html
Quote:
Originally Posted by aerohead
I think that it will definitely show at the gas pump.
As long as the trailing edges are round about where Mair's boat-tail profile would be,the air will separate at the tailgate area,then swirl into a captured-vortex;stuck against the tail,with the outer air streaming by.
It's that outer air which will have a chance to decelerate to a higher pressure before it does break away,which will raise the base pressure back there. 
........................The air immediately separates at the beginning of the cavity but does re-attach at the back,capturing a vortex on top,both sides,and bottom. |