On 2007-11-13 19:07:50 -0800, Dave said:


Now it appears that someone has come up with the idea of running a
vehicle on compressed air.

Compressed air engines are really just variants on steam engines.
Anybody remember the Freon based solar powered steam car? The idea was
that Freon would be stored in a tank in the car and cycled up to the
roof where it would be heated into steam for powering the car. The
steam would go to the engine and from there the now cooled liquid Freon
would go back to the tank.

There were some guys who took this a step further. They would heat the
Freon with a small burner when the sun was not enough. One guy built an
MG to run this way. He also was working on a 1966 Cadillac which
weighed 5000 lbs. He was going to use an 80 hp diesel to compress Freon
and run the car. He chose Freon over compressed air because it is a
lubricant, which would save wear and tear on moving parts, and the
contracting/expanding cycle of Freon kept you from losing so much heat
energy.

William Lear had a bus and a Monte Carlo powered by a closed circuit
steam turbine engine back in the '70s. However, he never put it into
production because (he claimed) adding expected features like air
conditioning and power windows was extremely complex and more than he
wanted to deal with at the time. The real reason it was never put into
production, of course, was that it used a turbine. The fluid was
something called "Learium," which was really just Freon. It ended in
bankruptcy, but it is claimed that someone bought the hardware and
built a water steam race car with it, proving that although the concept
worked well enough to set some land speed records for steam cars,
Learium was a total fraud and turbine engines were too inefficient for
use in automobiles. Sure, the turbine works great for land speed
records, but the engine only has to run for 10 minutes, so it is easy
to carry enough water to get that much time out of it. Most people want
a car that runs longer than that.

There is supposed to be an article on a Lear designed steam piston
engine in Car & Driver in 1969. It was said to have six cylinders,
twelve pistons, and generate 500 hp at 1000 psi. Trouble is, it was
Lear who made these claims and he never allowed anyone to take a close
look at the engine.

Back in the 1940s people were experimenting with hydrogen peroxide over
a catalyst bed, sometimes injecting kerosene and water to generate even
more steam. Might be a tad dangerous for use in the family car, though,
and I would bet that the pollutants would be a serious problem.

Despite all these problems, though, I would think it would be much
easier to get a steam engine to work with actual steam than with
compressed air.
--
Waddling Eagle
World Famous Flight Instructor