Electrically Powered Ultralight Aircraft

Orval Fairbairn wrote:
In article ,
Orval Fairbairn wrote:

In article . com,
James Sleeman wrote:

On Aug 6, 4:52 am, Larry Dighera wrote:
Electrically Powered Ultralight Aircraft
It's a nice idea, but realisitically there are too many problems, not
the least of which is battery size, weight, cost and safety. I don't
really see batteries as a viable in the near future (I struggle to see
them as viable in the distant future either).
Look at the problem this way: In an all-electric machine, you carry ALL
of your energy supply with you: fuel and oxidizer -- to make electricity.

With any IC engine, you carry the fuel only -- the air is free (20%
oxygen), so, at 15:1 air/fuel ratio, you would need 90 lb of air for
each gallon of fuel.

Therefore, for a nominal 50 gallon fuel capacity (300 lb), you would
have to carry an additional 7500 lb of air.

That is a lot of weight for a 3000 lb aircraft!

DUH! I meant 4500 lb of air! That is still a lot of weight penalty.


Well, to be fair Orval, you do get the 90% efficiency in an electric
motor, vs the 30% in an IC engine. You'd only have to drop 1500lb of
useful load with the electric motor.

Isn't the useful load of most light airplanes somewhere between 600 and
2000lbs?