On 11Oct2020 1945, xxxxxx@gmail.com wrote:
> Water can't be *much* more compact than LH2 drawn from said water.
> You're losing a crap lot of weight from the O2. I suppose it is
> possible that H20(l) can be more compact than H2(l) .
One tonne of liquid hydrogen takes up forteen cubic metres of volume.
Nine tonnes of water include one tonne of hydrogen, and has a volume of
nine cubic metres. You get about 1.55 times as much hydrogen into the
same volume, but the mass per quantity of hydrogen is nine times as
great. In CT, MgT and a number of other rule sets spaceships care about
volume, not mass, so water is useful if the referee is willing to go
with it. The downside is that it's very definitely unrefined fuel, even
if the ref is generous (I simply disallow using water as jump fuel), and
carrying it and then refining it requires a refinery/purifier, time, and
a tank to hold the water as well as one to hold fuel.

--
Rupert Boleyn <xxxxxx@gmail.com>