Compressed air as fuel?

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. There's a new
engine being developed, the Quasiturbine, that would be perfect for
this application.
For what it's worth.
Chris

Dancing Fingers wrote:



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. There's a new
engine being developed, the Quasiturbine, that would be perfect for
this application.
For what it's worth.
Chris


The straight answer?

Not on this, or any other planet in this solar system...

Richard

"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

On Jul 12, 9:23 am, Dancing Fingers wrote:
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. There's a new
engine being developed, the Quasiturbine, that would be perfect for
this application.
For what it's worth.
Chris- Hide quoted text -

- Show quoted text -

You can put the "quasiturbine" right in the same category as the 'air
car" and "Moller's flying car" all of them are vapor ware. To
address the 'quasitubine' specifically, It has been "under
developement for at least 10 years and I think longer with no
progress. It is an extremely complicated design for a rotary engine
with little or no improvement over the original Mazda (IIRC) rotary
engine.

The heat problem is not in getting rid of it. The problem is that
that heat was produced while compressing the air and is then thrown
away. Right there should be a clue as one of the major reasons why
and "air engine" is not an economicaly viable design. That heat costs
money and represents energy that cannot be recovered.

Harry K

"Harry K" wrote in message
s.com...
The heat problem is not in getting rid of it. The problem is that
that heat was produced while compressing the air and is then thrown
away. Right there should be a clue as one of the major reasons why
and "air engine" is not an economicaly viable design. That heat costs
money and represents energy that cannot be recovered.

This was already explained to the OP, and seems to have made no impression.

Vaughn

Harry K wrote:
snip

It is an extremely complicated design for a rotary engine
with little or no improvement over the original Mazda (IIRC) rotary
engine.

Wankel?

Dan, U.S. Air Force, retired

Dancing Fingers wrote:

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. There's a new
engine being developed, the Quasiturbine, that would be perfect for
this application.
For what it's worth.
Chris


Not only is the energy density of the compressed air ridiculously low
and nearly impossible to utilize efficiently, but nearly all of the
alternative energy schemes require that the entire set of propellant be
carried. With traditional fuels, the oxidizer is collected as it is
used. Between 12 and 17 pounds of air is ingested for each pound of
fuel carried.