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Helium is expensive and non-renewable. Hydrogen is cheap and plentiful, but it's
flammable. The lower explosion limit of Hydrogen in air is 4%, so as a first pass on
solving the problem of finding a lifting gas that's both cheap and safe, Hydrogen
could be diluted in air. However, since Nitrogen
is also cheap and is also non-
flammable (practically speaking, since nitrous oxides require a high activation
energy), a higher concentration of Hydrogen could be mixed with Nitrogen to
produce an even lighter gas that is also cheap and non-flammable.
[link]
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I'm anticipating somebody with maths to come along and poke holes in this balloon ... |
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Well, pure hydrogen won't burn by itself, so it's only a problem when it mixes with air. And if it's going to meet air, then any concentration of hydrogen that starts out at 4% or higher will burn. |
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Plus, the more you dilute the hydrogen, the more volume you need, which means more surface, which means more opportunities for the surface to be punctured. |
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It's six of one and roundabouts of the other. Hydrogen airships are, in fact, about as safe as helium ones. If a hydrogen airship springs a leak, and if it somehow finds a source of ignition, you generally get a big flame that starts some distance away from the envelope and doesn't do any immediate harm. It's only public perception that prevents widespread use of hydrogen as a lifting gas. |
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Pity there isn't an emergency drone to act as a bunsen jet
and direction burn in a needed direction. |
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Well, you could always mix it with Helium. Based on your
research, adding 4% would be completely safe and
marginally reduce the cost. Or you could add more.
Assume you verify [Max]'s assertions with safety testing, you
could sell a mix with 99% H and 1% He. You could say that
adding the He reduces the flammability (marginally), and
that the system is safe. |
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But helium is a plentiful and cheap, as a product of nuclear fusion. I'm sure we've invented *that* several times. |
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Nuclear fusion is indeed Baked and WKTE. |
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Well, you could mix Helium with SF6, but it kinda defeats the purpose. |
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Neon is underrated as a lifting gas. It's about half the
density of air. |
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That would be a steam balloon, which is WKTE - water (as a gas) has a little more than half the density of air. |
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//Reconsider Hydrogen
Have you considered Consider Phlebas? |
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Helium is baked and WKTE. Hydrogen is WKTE but you can't
bake it safely. |
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Actually, you can - in the absence of oxygen ... |
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Great idea to [Reconsider Hydrogen], kevinthenerd, as the He depletion on Earth will be a catastrophe. |
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At first, the German WWI war-zeppelins, using pure H² as the lifting gas, were near impossible to knock down during their siege of London, until later. They usually were able to limp home, be repaired, re-filled, and then return. (PBS documentary.) |
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Arthur C. Clark - (RIP) - mentioned that 80% He / 20% H² was the maximum [cheap] H² you could add to He and still be non-combustible. So a little bit of He savings there. |
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There is ~5 billion years of 1mm thick solid He on the surface of the moon [from cosmic rays] to be harvested. It is even lighter than the He on Earth, because they only have 1 neutron + 2 protons from Solar nuclear fusion, compared to the Terrestrial alpha particle He on Earth which is one nucleon heavier- (2 neutrons + 2 protons) - from nuclear fission. |
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I've been thinking about how to harvest lunar He for decades, but first we need to start extracting [more] He from natural gas here on Earth. Some wells (Texas / Oklahoma, USA) are as high as 6% He... |
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If we're going to start harvesting He3 from the moon,
using it for lifting gas is about the most absurdly
inefficient waste of resources that I can conveniently
think of. It's like mining and refining Iridium, then using
it for fishing sinkers or ship's ballast. There's any number
of nuclear fusion research institutes who would be happy
to take it off your hands for maybe 1000 or even 1000000
times what you could sell it for as a lifting gas. |
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// But helium is a plentiful and cheap, as a product of
nuclear fusion// - Not really, the quantities aren't there
yet and won't be for many a year to come. A gigawatt
fusion power station would be producing litres per day of
helium, not belching it out as an exhaust gas. |
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Your primary's absolutely packed with the stuff, why not use that ? |
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