Recently, Larry Dighera posted:

On Tue, 09 Jan 2007 10:19:00 -0600, James Robinson
wrote in :

Larry Dighera wrote:

"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:

Larry Dighera wrote:

http://www.teslamotors.com/

Well they say the motor weighs 70 pounds and produces 248 HP but I
can't find anything about the weight of the batteries.

Total weight is indicated as ~2,400 lbs (including air
conditioning). Given its 1:10 power to weight ratio, I'd say, if it
had wings instead of the beefy structure it requires to meet road
safety standards, it would fly. It wouldn't require any fuel.
Recharges fully in 3.5 hours.

The batteries weigh 900 lb., and put out 75 HP for an hour.

I didn't see those numbers on the Tesla Motors web site. Have you got
a source for that information? There is a chart here, but it is more
about marketing than engineering:
http://www.teslamotors.com/performance/performance.php

Your numbers seem to conflict to some degree with these:

http://en.wikipedia.org/wiki/Tesla_Roadster#Battery
Battery:
6,831 Lithium ion battery cells
About 450 kg
Full-charge time of three and a half hours
~56 kWh capacity

I don't have my hp W tables handy... if you do, how does Robinson's info
conflict, given that the weight is about right as "about 450 kg" ~= 990
lbs.

Intuitively, an electrically powered aircraft employing Li battery
technology still seems feasible to me.

The possibility isn't the question; what would it take?

And, this fellow seems to have his finger in the pulse of the electric
propulsion issue:

The reference is very interesting, yet I think this writer is off-target
in his critical focus on the Tesla. Would he pay $90k if it had the Altair
battery instead?

While the Altair battery offers some theoretical advantages over the Tesla
power pack, neither is a complete solution. The Altair battery's basic
configuration is 13v. @ 88 Ah.
http://www.altairnano.com/markets_amps.html

That isn't a very long drive in an electric-only vehicle. However, in a
hybrid there are potential advantages because it can be charged rapidly.
Unfortunately, it can also be discharged rapidly which can be a
significant hazard. In short, I'm intrigued, and I think that there may be
a future for PLI batteries. Additionally, the original Marketwire article
makes it seem that there is reason to be cautious about optimistic
predictions for this company, so perhaps the "bird in the hand" is the
best approach for Tesla, whether or not they can deliver on the
performance.

Neil