[freebeard]

My roommate is an engineer so I'll ask him for help too.

I support that choice.

I think I actually just had a eureka moment. That shell design you posted; what if I simply made a flat door on the front and back of the shell that could be "kicked down" to fold flush against the floor. Then when I'm putting down serious highway miles it's just a big tube that the air can flow through; hardly any frontal area (assuming 8-foot radius with 1-inch thick sandwich panel plus 1-inch of insulation, that's 0.347222 of square feet frontal area by my math).

Two words: Interference drag. That's sort of the opposite to what I'd hoped to convey. Have you thought about putting a propeller on the front to recharge the battery?

Let's try again. Are you familiar with the Template? Here it is implemented at a higher resolution.



This expression of the aerodynamic ideal combines a geodesic primitive with a Cartesian coordinate layout. Every edge length is a known quantity to 6 decimal places, and the layout can be based on triangles, diamonds or hexagons.

If you build that I'll owe you a six-pack of beer.

Now, as to the lever arm from the Tesla's natural roll center to the new center of pressure. Here is a post from 2009 that introduced Englar's work at Georgia Tech

http://ecomodder.com/forum/showthrea...ots-10972.html*

It's all gone behind a paywall but if you follow up you will see that he demonstrated using pumped air to increase/decrease drag, lift and ruddering. So if you truncate the rooftop 'tent' and it has kilowatts of power available you could use it to steer the top of the car relative to the bottom.

OTOH, I worry about the 8x20ft floor plan. Could you get by with 7x16ft?



I had one of these once. It was 23ft with the hitch, 7 ft wide with a 6' 2" ceiling. You're talking about perching the equivalent on top of you car. I hope you have a plan for off-street parking (a store-and-lock or something) so it doesn't have to be on top of the car all the time.

Edit: *Not the best link, it degenerates into a discussion of injecting steam into the wake. Two papers you want are

A New Aerodynamic Approach to Advanced Automobile Basic Shapes
Alberto Morelli

and

Alternative approaches to rear end drag reduction Technical Report
Torbjörn Gustavsson