"Dancing Fingers" wrote in message
oups.com...
Hi Guys,
I remember years ago Kitplanes did a series on the potential for
batterry-powered aircraft. Recently, I watCHED Future Cars on the
Discovery channel and this guy had developed a car that ran on
compressed air. This seems like a more viable fuel for aircraft then
batteries. Has anybody looked into it?

Air power has been looked into for commuter vehicles. There is a company
that has been promising to make something called the "Aircar" for several years
now. They always claim to be constructing a factory, have plenty of orders in
hand, and full production is always going to start "next year". Sound like
anyone we know?

The fact is that compressed air is a very thermally inefficient way to
store energy. The reasons are buried in basic, fundamental physics. The
problem is that when you compress air, it gets hot. That heat must be thrown
away. But that is not the only problem! When you go to expand the air to
produce energy, it gets cold! This reduction in temperature greatly limits
expansion and reduces an engine's output.

Making an efficient air engine is not a trivial exercise. To be efficient,
you must find some way of allowing the air to expand to many times its
compressed volume. This may be done several ways, but all of them increase the
complexity and/or the size of the engine.

Vaughn