Airship Hydrogen resupply

[JuliaL]

JuliaL, brilliant.

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I don't know where I got the 12 m^3 per kWh from. brainfart.com? Possibly a case of "don't drink and derive".
Seriously, I don't know how that number slipped in, probably a confusion of /kg and /kWh - thanks for catching it. The result looked too good to be true, eh?

So, your idea of using parts of the Aluminum structure sounds very interesting. I wasn't aware of that reaction. Yes, they land in a nice forest - they might have the good sense to land near a forest on purpose.
Of course, if they rip 6 metric tons of aluminum out, that will save them almost the 7000 m^3 lifting gas, doesn't it? This would make replenishing the gas pointless. But dropping ballast (from the hull or the engines), is too boring, I want them to have to do some mad science, either electrolysis or chemistry, to make it.

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Good, I like brilliant---specially when applied to me.
But your point that you don't need the gas if you can lose the mass is well taken.
You don't even need to shed the 5.6 tons.

My transfer function for H2 generation from Al & OH- is:
1kg(Al)/(27gm/mol)*3molH2/2molAl*2gmH2/molH2* 1/(0.0899kg/m^3)=~1.24m^3/kgAl
And every kg loss from airship mass reduces the required volume by:
1kg/(1.205kg/m^3-0.0899kg/m^3)=0.9m^3 per kg loss.
These functions meet in the middle:
1.24m^3/kg*massloss+0.9m^3/kg* massloss=7000*m^3
Which solves at massloss =~3300kg


You need some other motivation to do the task.  You need to take on cargo.
Could you be morally impelled to save some missionaries, their native bearers and luggage?.....Nah as an atheist (with no morality  ) I can't suggest that.
How about rescuing the Swedish Bikini Team? No, not P.Correct enough.
How about the Swedish Bikini Team dressed as nuns that you don't unmask until under weigh?  Oh the ambivalence, the ambivalence!

Could the electrolysis be driven simply by burning wood? They'd need a lot of wood, but that shouldn't be a problem for our friends.

The will-they-make-it-back is definitely a subplot.

Tubular! having the engines driven for both H2 generation and transport by a smoke puffing wood gas generator would be awesome and very steam punk.