Weight and size. (you did ask)

noel.wade wrote:
...And now for a slight thread-hijack:

OK, so no one here is arguing against the end-product: An
electrically-powered propeller or ducted fan.

Can I stop for a minute and say "WTF?" to the recent article about
how jet engines are the future of self-launch?
(I think this was in SOARING magazine, IIRC)

Jets are wonderful devices for specific missions (especially sustained
thrust at higher speeds, where props become less efficient). But in a
glider, at low speed and for short periods of time?

The article talks about how the jets are improving and becoming more
and more suited to use in a sailplane... But:
1) You still have to carry a dangerous, liquid, flammable fuel. Oh,
and that fuel can turn to vapor that might incapacitate the pilot if
breathed, and the fuel can EAT your aircraft's core materials in some
cases, if it seeps into the structure - yipes!

2) Despite being reliable and simple compared to an internal-
combustion engine, jet engines still have as much or more complexity
than a simple electric motor. The heat and stress on bearings and
other parts has got to be higher than an electric motor, right?

3) Jets put out a LOT more HEAT than an electric motor. Can anyone
tell me how resins that cure at ambient-temperature levels are
supposed to hold up well when a jet engine retracts inside the
fuselage while its still hot? I've heard that they can cool down
efficiently in as little as 30 - 45 seconds; but what about operator
error? What about the distance / altitude lost during that wait
period? I know the drag of a turbine is less than a big ol' prop; but
still...

4) With a jet, you already need electrical equipment, for the starters
and igniters and such. Why add a whole second fuel/energy-delivery
system (i.e. Jet-A) when you can stick with a single source and a
single output?

OK, OK, I'll quit ranting... :-P

--Noel