There are electric winches that can launch a glider to 2000' AGL - it takes
about 1KWh. From that, I would expect that an electric tug would require
more than 5 KWh to do the same job since it is launching both the glider and
itself and must have reserve power to return for landing.

A problem for both the electric winch and this hypothetical tug is the
availability suitable power on the flight line. To recharge in a reasonable
time, you are going to need serious power service - maybe 440V 3-phase 200
amp service. That's not trivial to work with.

It's sort of like a neighbor of mine who was complaining about the price of
gas - his SUV only gets 12MPG. I suggested he think about pushing his 6000
pound truck 12 miles by hand. That would give him the proper respect for
the energy in a gallon of gasoline - and its value.

Liquid petroleum fuels are extremely energy dense. It's going to be really
hard to replace that with electricity. But maybe not impossible.

Bill Daniels


"Paul Hanson" wrote in message
...
A technology I have not seen even mentioned in this
lengthy (but very good) thread is that of carbon nonotube
enhanced ultracapacitors, which have the promise of
the energy density of the latest lithium polymers,
but almost infinite discharge cycles and can be recharged
in seconds. What would make a whole heap of sense (to
me at least), would to develop an electric tow plane
based around this technology. Quiet, efficient, hardly
affected by density altitude, quick as refueling with
avgas when charges are needed, etc. This would get
our fleet of non-powered aircraft off the ground just
fine, without angering the encroaching land developments
and such. An efficient/viable electric towplane, that's
what we need. I'm sure other developments would stem
from it too of course.
Hats off to all people/groups considering alternatives
at this point, and down with the naysayers!
Paul Hanson


At 23:24 09 August 2007, Maxwell wrote:

'Larry Dighera' wrote in message
. ..

I would think that would be close to the bare minimum.
I flew a fixed wing
hang glider on 10 HP for a while back in the 70s. A
Manta Fledgling, and
it
was very underpowered. Maybe 100 fpm climb or so.


I would guess the rigid wing would have a higher L/D
than a powered
parachute's 4:1, so it might require less power.
Does that sound
correct in your experience?

Indeed, quite a bit less from my experience. I think
my Fledge was supposed
to be around 10:1.



"Do the usual, unusually well"--Len Niemi