why would a rigid airship body with helium or hydrogen would float but not one with a vacuum inside?

Question

My thinking here is that if my rigid airship body is, say, 24g, with vacuum, why would it float with helium or hydrogen inside, when they have mass and thus weight? Makes very little sense, unless it has something to do with the density?

I haven’t actually done this yet, and I’m working out ideas for one. Everyone I know tells me I’m wrong for thinking a vacuum (assuming a full one, although they are elusive) would float over helium or hydrogen.

In: 11

Answer 1

A vacuum airship would work, as it would have the best buoyancy characteristics compared to other gasses.

However it presents a hurdle in that while you can fill a thin bag with helium, how do you get your vacuum chamber to retain its shape under atmospheric pressure? Any container we can build would need to be far heavier in order to retain its shape than its buoyancy can lift.