91–100 of 119 posts
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Diatomic hydrogen is bigger than helium, less prone to diffusing through a membrane.
Have you worked with hydrogen? Being less prone to leaving than He is an extremely low bar and very far away from the claim that it doesn’t ever diffuse through anything.
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Totally unrelated, but a fascinating tidbit from that wikipedia link: > Venus has a CO2 atmosphere. Because CO2 is about 50% denser than Earth air, ordinary Earth air could be a lifting gas on Venus. This has led to proposals for a human habitat that would float in the atmosphere of Venus at an altitude where both the pressure and the temperature are Earth-like.
This seems like the perfect premise for a scifi novel. I wonder why we don't see it more.
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Have you worked with hydrogen? Being less prone to leaving than He is an extremely low bar and very far away from the claim that it doesn’t ever diffuse through anything.
Diffusion works both ways, too. Oxygen outside of the membrane will also slowly diffuse into the hydrogen and helium mix, further complicating any attmpts to remain non-combustible.
Anyone thought about using aerogel infused by pure hydrogen, wrapped in plastic? In case the wrap is breached it should make mixing with air slow, preventing explosion. (I am aware that aerogel is absurdly expensive in needed quantity. Just a thought experiment.)
It got me wondering if the increase lift capacity would be added factor, but quick calculation shows that it would only gain an extra ~1% of lift. So it would really just be a cost question: https://en.wikipedia.org/wiki/Lifting_gas
I tried to convince a group that: 1. Hot air balloons get their lift from hot air; and, 2. Dirigibles can get their lift from hydrogen; thus, 3. Hot hydrogen dirigible? Blah blah blah ... exploding dirigibles ... blah blah blah. The lifting efficiency is outrageous .
You'd want to be damn sure about the reliability of your thermocontroller though.
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Not just on Venus; Buckminister Fuller proposed to build floating cities on earth: https://en.wikipedia.org/wiki/Cloud_Nine_(sphere)
How much would a mile-wide geodesic sphere cost to build?
One cost-reduction approach would be that the beams could be mass-produced for efficiencies of scale. The top panels could be simply plastic sheeting.
Interesting! Living in Friedrichshafen (Germany) the birthplace of the Zeppelin, I'm wondering if this would be a valid option, because the Zeppelin NT that is used here in the summer uses only Helium AFAIK. The Zeppelin NT has an emergency drain that would essentially mean releasing 7.400 m³ worth of helium. I will definitely ask a family member that works at Zeppelin what he thinks of this research!
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I tried to convince a group that: 1. Hot air balloons get their lift from hot air; and, 2. Dirigibles can get their lift from hydrogen; thus, 3. Hot hydrogen dirigible? Blah blah blah ... exploding dirigibles ... blah blah blah. The lifting efficiency is outrageous .
Just crazy enough to work. Hydrogen doesn't autoignite till 500 degrees celsius, while your average hot air balloon only heats gas to 100 degrees. You'd want to be damn sure about the reliability of your thermocontroller though.
I have often wondered about super strong materials, a sphere with vacuum inside.
Anyone thought about using aerogel infused by pure hydrogen, wrapped in plastic? In case the wrap is breached it should make mixing with air slow, preventing explosion. (I am aware that aerogel is absurdly expensive in needed quantity. Just a thought experiment.)
Or you could skip the aerogel entirely and use a hard, incompressible shell and pull a partial vacuum inside. Of course we don't currently have any materials both strong and light enough to do that. Neal Stephenson proposed such vehicles made from thin shells of diamond in The Diamond Age .
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Or you could skip the aerogel entirely and use a hard, incompressible shell and pull a partial vacuum inside. Of course we don't currently have any materials both strong and light enough to do that. Neal Stephenson proposed such vehicles made from thin shells of diamond in The Diamond Age .
Right and when one shell breaks, the shrapnel breaks the other ones and everything around:)
But they'd certainly look cool.