Richard Riley wrote:
On Mon, 03 Oct 2005 10:52:49 +1300, Frank van der Hulst
wrote:

wrote:
: And hydrogen is a lightweight fuel too, for lower fuel load.
: But suppose you want some extra juice sometimes, for more
: maneuvering/lifting power.
:
:Hydrogen is only a lightweight fuel in its uncompressed, gaseous form.
:In fact, in terms of energy per Kg, hydrogen is not a good fuel. Storing
:hydrogen in sufficient density to be useful requires strong (read heavy)
:tanks.

Liquid hydrogen has the most energy per pound of any chemical fuel.
It has 39,000 Wh/kg, gasoline only has 12,200 Wh/kg.

Unfortunately it is also not very dense - even in it's liquid form.
Liquid hydrogen has a density of 0.07 grams per cubic centimeter,
whereas water has a density of 1.0 g/cc and gasoline about 0.75 g/cc.

Oops, yes, you're right. It was in terms of energy/volume that hydrogen
is poor, NOT energy/mass.

Therefore the container to hold your liquid hydrogen needs to be large.
It also needs to be strong, and therefore heavy.

Therefore, as Richard said, hydrogen won't be a practical aircraft fuel
unless the storage issue can be solved.