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In some questions here (and in other sites), when the subject of a floating spaceship is addressed, I always see someone suggesting super-heated Helium of Hydrogen. However, I can't find anywhere about this subject, google only shows me normal types of Helium airships or some kind of Helium plasma cutting technology.

I'm interested on the possible uses of super-heated Helium to levitate massive things on my histories (like hovertanks or cargo ships), but again, I can't find anything about its capabilities.

The closest thing I could find around this subject is that, according to a random person on Quora, is that Heated helium balloons (as hot as normal hot-air balloons) could increase its buoyancy in 8%. And again, I couldn't find anything confirming this affirmation.

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The most lift would be for a vacuum balloon.

This is covered in this question: Could a Super-Light Gas Improve Heavy Armor?

A balloon provides lift because the mass of the volume occupied by the balloon is less than the mass of the atmosphere it displaces. The difference between those two masses is the amount of lift the balloon provides. A cubic meter of air on Earth weighs 1.29 kg so that is the maximum lift you can get from a balloon.

As you heat a gas it gets less and less dense. Hot helium has less mass per volume than cold helium. Hotter helium has even less. HELIUM FREAKING PLASMA has less mass than hot gas. The hotter you get it, the closer the mass comes to 0.

But it will not be mass 0. No matter how hard it tries helium will never have less mass than vacuum and none will ever provide more buoyancy than vacuum. And you won't either hydrogen so quit smirking.

You gases should not feel bad about yourselves because of that. You are gases and you can do so many awesome things vacuum cannot. Like provide interior structural support for the skimpy little balloon just by virtue of your presence.

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    $\begingroup$ You may want to add that normal not superheated helium already provides 85% of the maximum theoretical lift; and that $\sqrt[3]{1/0.85}$ is about 1.05, so instead of superheating the helium to a zillion degrees one could just increase the linear dimensions of the balloon by 5% and get the same amout of lift with gas at standard temperature. $\endgroup$
    – AlexP
    Commented Nov 14, 2021 at 22:39
  • $\begingroup$ @AlexP - ah, the voice of practicality. But then what will they do with all their HELIUM FREAKING PLASMA? $\endgroup$
    – Willk
    Commented Nov 14, 2021 at 22:45
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    $\begingroup$ Why, they will use their million degree helium plasma to produce energy from nuclear fusion! $\endgroup$
    – AlexP
    Commented Nov 14, 2021 at 22:46

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