"Dancing Fingers" wrote in message
oups.com...
On Jun 26, 10:23 pm, Orval Fairbairn
wrote:
In article .com,
Dancing Fingers wrote:

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?
just curious.
Chris

You ned either:
1. a very long hose attached to a compressor or

2. a filament-wound balonium/unobtanium air tank filled with air
compressed to 100,000,000 psi.

Otherwise, you just can't carry enough compressed air around to make a
practical vehicle.

The "Future Car" ranks right there along with Moller's "Skycar," in that
it is all vaporware.

I certainly don't think that compressed air would power a airliner but
it might be viable for small commutter flights. It seems like the
heat issue would only be an issue on the ground, during refueling,
although cabin heat would be a challenge. I was really wondering if
anyone had ever calculated the energy per cubic foot compressed air
can hold, relative to gasoline, diesel and hydrogen.

Kindly compare energy densities for yourself.

Jet fuel 11,694 Wh/kg
Gasoline 12,200 Wh/kg
Compressed air 34 Wh/kg

For a given weight of fuel, your air-powered "commutter" aircraft would have to
somehow get by with less than 1% of the range that it would have with
conventional fuel.
Source: http://xtronics.com/reference/energy_density.htm

Of course, that is gravimetric density and you asked about volumetric density.
Volumetric density would probably be an even worse comparison, but would depend
greatly on the air storage pressure you wish to assume. Naturally, you must
design your "fuel tank" heavier and heavier as storage pressure increases.
Exotic materials would help, but not enough. Also, high pressure air tanks must
be round, but the space available to contain the tank will not be round, so much
potential storage capacity would be lost.

There's a new engine being developed, the Quasiturbine, that would be perfect
for
this application.

The type of engine would not matter. You just can't carry enough stored energy
to be practical.

For what it's worth.

It is worth nothing

Vaughn