Wallace Berry wrote, On 5/15/2013 6:18 AM:
In article ,
Eric Greenwell wrote:

small fuel cell.

I've wondered if a gas-electric hybrid would be practical. A gas motor
powerful enough to supply half the energy of a 2000' climb at 500 fpm
would be about 20 hp, a fair sized motor. So again, maybe the solution
is a big enough Li battery to do the whole 2000', then use 4 hp motor to
recharge the battery over the next 30 minutes or so.

Apparently there was a gas-electric hybrid glider at the AERO
Friedrichshafen show, or at least a poster about one. SoaringCafe has
pictures from the show. One pic is of a diagram of an Albastar 18m
glider with internal gasoline engine driving a generator linked to a FES.

I like the idea of starting the motor before you have to commit to using
it. There is a glider with an enclosed, internal gasoline engine - the
Stemme - but it can't be started independently of propeller operation,
and the drive shaft is a difficult technical problem requiring the side
by side seating. The Albastar has a substantial engine of 65 hp, and the
use of using a generator/electric motor for power transmission to the
propeller gives it a lot of flexibility in design the Stemme did not have.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl