Vaughn wrote:
On 12/12/2012 2:37 PM, george152 wrote:
And how would such a machine fit into an average fleet of training
aircraft ?

Training is all about economics, and the economics for battery powered
aircraft (or virtually any new aircraft) for the training market simply
aren't there...and may never be.

Most of the day it would be out either being recharged or having the
battery pack replaced.

Not necessarily so. You could have quick change battery packs that
presumably would take no longer to swap than it takes to refuel a plane.
However, that would require multiple battery packs, so economics rears
it's ugly head again.

And range.
Quickly improving. A few electric models are plenty good enough for
sport use today.

Any landings and refuelling away from base would have to take account of
facilities at the destination..

As they always have...

At the moment it sounds far to complex to return revenue

Complex? Nonsense! Electric planes can be quite simple compared to an
equivalent IC plane.

Return revenue? You mean economics? That's another matter! It's
actually the real issue, and perhaps the deal killer.


There was one electric powered aircraft in the 30s that looked great but
could only fly circuits..

Your point?


The real problem for for any vehicle application is charge time which
is limited by basic physics and how much power you can get down a wire
and through a practical connector.

Say you have the equivelent electric airplane of your typical bug smasher
that has 180 HP and runs at 75% power.

Neglecting any losses and conversion efficiencies, which just make the
numbers worse:

That is 180 X .75 X 745.7 = approximetely 100 kW.

If you fly for 3 hours you use 300 kWH.

Assume the battery voltage is 100 V, which is a rather ballpark typical
value for an electrical vehicle, you have to supply 3 kAH to charge the
battery.

If you want to charge the battery in a half hour, your cable and connectors
must carry 6,000 Amps.

Increase the battery voltage to 200 V and an hour charge time and you still
have to carry 1,500 Amps.