Airship Hydrogen resupply

[Anomalocaris]

JuliaL, brilliant.

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.

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.

The density of hydrogen is about 0.1Kg/m^3.  The density of air is about 1.21kg/m^3.  So bouyancy of hydrogen is about 1.2Kg/m^3, or about 12kg of bouyancy per kg of hydrogen.  So the original 70000 m^3 of hydrogen would have had lifting power of about 84000 kg, or 84 tons.  

If this airship carried 22 tons of fuel and 50 tons of payload, that leaves 12 tons.   Take out engine, envelop, hydro bladders, crew, and Swedish nuns, what remains would be aluminum structure.   With 1920 technology 240 hp motor durable enough to run for days, including radiator, oil pump, nacelle, etc would probably weigh 500kg each.  Let's say crew of 10, they would weigh about 1000 kg.  Swedish nuns might be lighter than air, but being thin they probably don't displace much air and so can't provide much bouyancy.  That leaves 9 tons for structure, envelop, and hydrogen bladders.

So I don't see how there is enough structure such that removing 6 tons of it would still leave the airship able to hold itself together.

[Anomalocaris]

The 7000 m^3 of lost hydrogen reduces lift by 8.4 tons.

According to JuliaL's calculation, burning a ton of fuel to make hydrogen would generate only a fraction of a ton of lifting capacity.

So why not just jettison 8.4 tons of fuel?

[Jackalope]

So why not just jettison 8.4 tons of passengers?

FTFY

[Anomalocaris]

So why not just jettison 8.4 tons of passengers?

FTFY

8.4 tons would be about 80-100 passengers.

[JuliaL]

Oh cool, Julia, did you know this:

https://en.m.wikipedia.org/wiki/Water_gas

I think I sort of knew about it.  There seems to be a couple of industrial processes used to generate lighting gas starting in the late 18th century and persisting till the introduction of electrical lighting.  History of Manufactured Gas  Isn't the internet amazing...at least, I'm still amazed.  I expect that my sons will find it dull & pedestrian to have any subject they wish to investigate immediately available and take it for granted as I take for granted the electrical distribution grid.
My vaguely remembered introduction to lighting gas production came from an elementary school reading primer where he big event in one story was having that new-fangled thing, gas lighting, installed in town.  We also had some exotic civil engineered facilities for storage that were demolished in my time.  They were basically a pool with a frame above that guided an inverted tank like a giant upturned cup.  The gas was pumped in from below and the weight of the tank provided pressure for distribution.

I also remember when the  'sticking your head in the oven' method of suicide became impractical as the CO in cooking gas was replaced by CH4.

<snip>

So I don't see how there is enough structure such that removing 6 tons of it would still leave the airship able to hold itself together.

I don't know if you've seen The Flight of the Phoenix?  The reconstituted machine need not be much like the original.  Besides, we're in a novel, it's going to run on narrativium anyway.

[Jackalope]

FTFY

8.4 tons would be about 80-100 passengers.

Right then, over the side with the lot. Now's no time for getting squeamish.

[Alex K]

More input/inspiration for the novel

https://www.youtube.com/watch?v=d4jq7oRxw-g

[Jesster]

Here's all I have to add to this conversation of Zeppelins.

https://www.youtube.com/watch?v=ZDwotNLyz10

[Alex K]

Here's all I have to add to this conversation of Zeppelins.

https://www.youtube.com/watch?v=ZDwotNLyz10

I was 2 months old when this took place. Otherwise I would've gone

https://www.youtube.com/watch?v=7B_kjHTWT1g

but as far as live recordings go, I prefer this old one even if many famous songs don't exist yet

https://www.youtube.com/watch?v=DohsUDR7...zXvcGLDE5h

[The Grand Nudger]

Steampunk, right?  

Enjoy.

https://www.youtube.com/watch?v=cqjn3mup1So