Re: Why Willie's ideas for hydrogen fuelled aircraft are BONKERs !
- From: Eeyore <rabbitsfriendsandrelations@xxxxxxxxxxx>
- Date: Sun, 30 Dec 2007 20:27:54 +0000
Monkey Clumps wrote:
Eeyore wrote
Aside from the very considerable extra space required for H2 fuel which
makes any hydrogen fuelling of an existing aircraft design utterly
impractical without extensive rebuilding/conversion and 'megastretching'
with attendant weight increases that lose the very benefit of hydrogen's
lower weight in the first place, we did not pursue the added weight of
the hydrogen tank.
Willie has asserted that the tank will weight a fraction of the weight
of the hydrogen contained.
THIS IS PURE NONSENSE like most of his ramblings.
I looked for sources of info about H2 tanks and it's apparent that the
tank weights VASTLY more than the H2 fuel ! Current benchmarks figures
seem to hover around 4.5 - 6.5% for the weight of the contained hydrogen
!
This was the very best advance I could find ....
"QUANTUM Fuel Systems Technologies.......... announced today that it
demonstrated a hydrogen storage tank with a world record 13% hydrogen
weight efficiency. This breakthrough
offers a dramatic weight reduction in hydrogen storage technology and
will
significantly improve on-board energy storage in aircraft and spacecraft
applications where weight is critical."http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/stor...
So the hydrogen is 13% of the weight and the tank is the other 87%.
That's a ratio of 1:6.7
And this is supposed to be a BREAKTHROUGH !
Instantly all Willie's plans for H2 aircarft can be dismissed as pure
pipe dreams. The weight of their fuel tanks would mean they'd never get
off the ground.
Even if that great breakthrough could be 'doubled' in hydrogen storage
efficiency, there would still be no net weight advantage and of course
the space required and attendant extra fuselage will increase weight to
the point where it's STILL a dead loss.
Maybe if H2 tanks could be made no heavier than the fuel inside there
might be a long odds chance of viability. I don't see how that could
ever be acheived if the best materials we have today are seven times off
that target.
Graham
Another issue is that this article was about a fully sealed,
pressurized H2 tank rated for 5000 psi. For the fuel on an airplane I
would think you would want to use non-pressurized thermally insulated
tanks, which which of course would add volume and weight for the
insulation, but would greatly reduce the loading on the tank walls,
which would greatly reduce the overall structural weight for the tank.
I wonder how greatly the weight would be reduced for LH2 storage myself. I shall look into it. There's another whole
host of problems associated with that too of course.
Graham
.
- References:
- Why Willie's ideas for hydrogen fuelled aircraft are BONKERs !
- From: Eeyore
- Re: Why Willie's ideas for hydrogen fuelled aircraft are BONKERs !
- From: Monkey Clumps
- Why Willie's ideas for hydrogen fuelled aircraft are BONKERs !
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