Re: hydrogen powered planes

From:         e.h.bogart@larc.nasa.gov (Ed Bogart)
Organization: none
Date:         29 Nov 95 01:36:15 
References:   1 2
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In article <airliners.1995.1843@ohare.Chicago.COM>, ehahn@bass.mitre.org
(Ed Hahn) wrote:

> Despite the bias (which I will not address one way or another) that
> appears in this article, there are several technical problems to be
> overcome regarding aviation use of H2 which need to be addressed:
>
> 1) storage capacity:  Gaseous H2 would take up too much volume to be
> useful given existing aircraft.  Totally new aircraft would need to be
> designed, which would be quite large.  Liquid H2 would require
> cryogenic storage capabilities, which again would require entirely new
> aircraft designs to be efficient.
> [snip]

There is another problem with H2 storage that may be even harder to get
around.  Most common aircraft matl. is permeable to H2 in gaseous
or liquid state. This means that leakage is inevitable and must be
dealt with in design (doable) and operation (BIG problem).

>
> 2) safe storage:  Unlike jet fuel, which has a very narrow fuel-air
> ratio in which it will burn, H2 is quite flammable over a wide range
> of fuel-air ratios.
> [snip]

Not only is H2/air flammable over a wide range of mixtures, but the energy
required to ignite it is orders of maginitude lower than even gasoline/air.
When you combine this with the leakage problem, you can begin to see the
practical problems of an H2 system.

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