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Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

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Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#81

Post by JumpCrisscross »

zokier wrote: post #22
ryandvm wrote: post #14

Earlier quoted context omitted.

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.

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?

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#82

Post by r00fus »

voakbasda wrote: post #45
nwah1 wrote: post #43

Earlier quoted context omitted.

But they are still flying bombs, even without crew.

Flying bombs that are being controlled remotely. And we know there’s no possible way that a hacking or ransomware group could exploit that channel and fly it into a couple of towers, right? Inconceivable!!

Fly-by-wire control of passenger airplanes hitting the World Trade Center was the plot of the 2001 series The Lone Gunmen[1]. Yes, that was 6 months before 9/11.

[1] https://en.wikipedia.org/wiki/The_Lone_Gunmen_(TV_series)#Si...

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#83

Post by Hypx_ »

jodrellblank wrote: post #47
ravenstine wrote: post #31

Earlier quoted context omitted.

How could hydrogen be a feasible approach to lifting any amount of cargo if aerogel of all things is too heavy? I just find it hard to believe that even the volume of aerogel required to support enough hydrogen to lift a useful amount of cargo would approach even a tiny fraction of the weight of the cargo itself, but perhaps I'm not imagining things correctly.

Airship Hindenburg had 200,000 cubic meters of lift gas[1]. Air masses 1.2 Kg per cubic meter, so 240,000Kg of air in that volume normally. Helium masses 0.18Kg per cubic meter[2], so replacing that volume with Helium gets it down to 36,000Kg. Hydrogen masses 0.08Kg per cubic meter[2], so replacing that volume with Hydrogen gets it down to 16,000Kg. Huge balloons containing almost-nothing, as soon as you replace the…

You have to be careful with the calculation here: The airship must also include the weight of the structure, and aerographene could potentially need much less structure than giant gas balloons.

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#84

Post by thechao »

jrexilius wrote: post #10

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.

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#85

Post by bawolff »

ryandvm wrote: post #14
jrexilius wrote: post #10

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

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.

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#86

Post by dandotway »

Hydrogen Embrittlement[1] is not discussed in the link, an effect where hydrogen diffuses into metals and causes them to become brittle and crack. Many aerospace materials are especially vulnerable: high strength steels, nickel and titanium alloys, etc. Fueling a disposable balloon or rocket with hydrogen is one thing, but a vehicle that can safely be refilled with hydrogen over and over for decades is quite another. (Recall how the rust red Space Shuttle External Tank was not recycled like the white SRBs were and was the only large expendable component each launch.)

[1] https://en.wikipedia.org/wiki/Hydrogen_embrittlement

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#87

Post by jodrellblank »

m4rtink wrote: post #71
jodrellblank wrote: post #47

Earlier quoted context omitted.

Airship Hindenburg had 200,000 cubic meters of lift gas[1]. Air masses 1.2 Kg per cubic meter, so 240,000Kg of air in that volume normally. Helium masses 0.18Kg per cubic meter[2], so replacing that volume with Helium gets it down to 36,000Kg. Hydrogen masses 0.08Kg per cubic meter[2], so replacing that volume with Hydrogen gets it down to 16,000Kg. Huge balloons containing almost-nothing, as soon as you replace the…

It would still have some compressible strength, right ? While not really being crushed under its own weight by default. So couldn't you build, say a giant pyramid reaching out into the stratosphere using hydrogwn infused aerogel ? :)

You could build a giant space pyramid out of anything in principle, according to Isaac Arthur on YouTube[1]. The limiting factor quickly becomes the size of "giant" needed for most materials and the limited size of Earth to have a wide enough base. Maybe being Hydrogen-infused would mean less pressure on the lower levels and able to build it higher.

Really though, doesn't AeroGel work by being mostly nothing? The more gas and less substance it has, at some point you may as well use a cloth balloon and only have the surface area size, no?

[1] In this video on Space Elevators - https://www.youtube.com/watch?v=dc8_AuzeYKE

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#88

Post by Dylan16807 »

Sporktacular wrote: post #40
beervirus wrote: post #19

Earlier quoted context omitted.

Diatomic hydrogen is bigger than helium, less prone to diffusing through a membrane.

Leading to an increasing percentage of hydrogen that will exceed the danger threshold. Helium level will need to be monitored and replenished.

You have to monitor and replenish no matter what.

That's part of why the comment said "a percentage" you don't have to refill.

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#89

Post by Dylan16807 »

trutannus wrote: post #65
ncmncm wrote: post #50

Earlier quoted context omitted.

Except, they are not flying bombs. Notably, the only people killed when the Hindenberg blew were on board. And, fewer than half of them. The flames in the film were the (very flammable!) gas bag itself and the kerosene fuel. The escaping gas went up and away. A modern craft would not be made of readily flammable material.

Your comments are filled with misinformation: The gas-bag and paint theory is debunked: https://www.airships.net/hindenburg-paint/ The "nobody died from the hydrogen" line is debunked: https://www.airships.net/hindenburg/disaster/myths/#advocate... That the craft is made out of flammable material is debunked: https://www.airships.net/hindenburg/disaster/myths/#flammabl...

> The "nobody died from the hydrogen" line is debunked

I don't see that claim in the comments you're replying to.

Re: Can helium be mixed with hydrogen to form a non-explosive mix? (2003)

#90

Post by Dylan16807 »

trutannus wrote: post #79
ncmncm wrote: post #78

Earlier quoted context omitted.

Talking about "pedantic nitpicking" does not favor your argument. Inventing claims from whole-cloth to debunk does not favor your argument. The world uses literally millions of tons of hydrogen every year, industrially. That the only event of any note that you can get any traction with was over 80 years ago should give you a clue. Noisy scaremongering does not improve anybody's life. Give it a rest.

You've given me a good laugh here. It's clear to pretty much anyone what I mean about industrial uses, so you're just responding to what you mistake as pedantry with pedantry. Anyway, I won't spend any more time here. Have fun, you've picked a strange hill to die on.

You're the one getting the issues backwards (oxygen leaking in vs. hydrogen leaking out, explosion vs. fire). Someone helpfully correcting you is not being pedantic or dying on a hill.

You're the wrong one, sorry.

Edit: Oh, you the same person as that other comment. You're completely imagining the claim that hydrogen didn't kill anyone! I'm not surprised you feel such a sense of superiority if you're that confused about what's actually being claimed here.

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