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Old October 5th 05, 10:43 PM
Terry Spragg
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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.


Unless you are driving an anti-static engineered lifting body shaped
dirigible, in which case, compressing or decompressing a little of
the surplus fuel / bouyancy medium using a "bouyancy bladder" device
allows ascent and descent without actual fuel expenditure, except
that required to compress the gas when descending. Quite the
inverse of a normal flying vehicle, where energy is expended to ascend.

Has anybody analyzed that in terms of fuel efficincy?

Terry K