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[Il Palazzo]

There's very little to be gained from vacuum balloons versus e.g. helium or hydrogen balloons, lift-wise, though.

[hops]

The latter is why it's interesting in my opinion.

Of course, it also implode violently so we need really strong material. But the idea is that, theoretically, if we could somehow produce superstrong material more cheaply than mining for helium (or however you get helium) then we can cut the cost of airships.

Not to mention that vacuums can't catch fire, so a vacuum airship would not cause a Manatee-Class catastrophe.

[hops]

Also people smoothies.

[Angle]

Also, if you want it to float in a helium atmosphere, you'd need something lighter than helium - Like vacuum.

fakeEdit - Helium doesn't burn, you're thinking of hydrogen.

[hops]

For some reason people don't use helium in airships, so I assumed they're too heavy for that task. Vacuum is massless and non-combustible, so not only that it doesn't burn, it's also slightly superior to hydrogen in term of lift.

[Il Palazzo]

For some reason people don't use helium in airships

All airships use helium nowadays. It's practically as good as hydrogen, only more expensive and without the explosive risk.

[Angle]

Helium is too expensive to make much economic sense.

[hops]

Yeah, I guess that it's a question between Expensive Fictional Material and helium. But hey, that's what material science is for, right?

[Il Palazzo]

Helium is too expensive to make much economic sense.

To do what? 75-ish bucks per thousand cubic feet is not that expensive if you want to fly a dirigible.

[Urist Arrhenius]

Helium is too expensive to make much economic sense.

To do what? 75-ish bucks per thousand cubic feet is not that expensive if you want to fly a dirigible.

Problem is helium escapes the atmosphere, so we're actually losing it over time.

[Il Palazzo]

Helium is too expensive to make much economic sense.

To do what? 75-ish bucks per thousand cubic feet is not that expensive if you want to fly a dirigible.

Problem is helium escapes the atmosphere, so we're actually losing it over time.

That's only a problem if you're considering geological timescales.

[Sergarr]

Helium is too expensive to make much economic sense.

To do what? 75-ish bucks per thousand cubic feet is not that expensive if you want to fly a dirigible.

Problem is helium escapes the atmosphere, so we're actually losing it over time.

That's only a problem if you're considering geological timescales.

And if you ignore just how much materia gets into our planet with the space dust. IIRC it's about 200 tons of stuff per year!

[i2amroy]

For some reason people don't use helium in airships, so I assumed they're too heavy for that task. Vacuum is massless and non-combustible, so not only that it doesn't burn, it's also slightly superior to hydrogen in term of lift.

The cost of a balloon envelope made out of some material strong enough to resist atmospheric pressure is much, much greater than that of a treated cloth envelope + lifting gas. And that's not even considering that the treated cloth is generally much lighter than any sort of rigid structure that could resist that pressure, which would mean that your envelope size would need to be much larger with a rigid vacuum balloon than a normal one (which would further drive up the cost).

Additionally if you poke a hole in a balloon of hydrogen the fact that there is basically the same pressure on both sides means that while you do have a leak, it's a fairly slow one. Poke a hole in a vacuum container, on the other hand, and you very rapidly will have a container full of air that is no longer providing any lifting force.

[Urist Arrhenius]

Helium is too expensive to make much economic sense.

To do what? 75-ish bucks per thousand cubic feet is not that expensive if you want to fly a dirigible.

Problem is helium escapes the atmosphere, so we're actually losing it over time.

That's only a problem if you're considering geological timescales.

And if you ignore just how much materia gets into our planet with the space dust. IIRC it's about 200 tons of stuff per year!

The escape from the atmosphere is actually relatively fast, and is the reason we don't recapture any from the atmosphere: it can never reach reasonable concentrations. And, AFAIK, what gets into our planet from space dust contributes only to this atmospheric helium, which we don't have access to. All of our helium is mined, having been produced by radioactive decay. Which will fortunately continue happening, but also means there's a fairly limited rate of supply.

[i2amroy]

Well once we get the things we need for fusion working more efficiently we could always just get our helium as the byproduct of our hydrogen fusion power plants. There's evidence now that there are probably great abundances of Hydrogen in the Earth's crust, in some places potentially reaching as much as 1000 L per cubic meter of rock. Combined with fusion our near-limitless supply of hydrogen could very easily become a near limitless supply of helium as well.