Comment by alpos | Hacker News Reader

Comment by alpos | Hacker News Reader

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The bigger problem with hydrogen is making a container it doesn't escape so much faster than Helium as to negate the extra lift advantage.

You can let it leak out, but then you need to carry extra compressed gas above what is already needed for the same issue with helium.

You can build a tighter, multi-layered envelope, but then you're adding weight and quickly negate the extra lift. This is the category your tens of thousands of sacs idea falls in. The problem there is that you are massively increasing the surface area through which the hydrogen can slip out. You have to keep in mind, to a single hydrogen atom, everything we consider "solid" looks more like a fishing net for catching a whale. Our best designs so far usually involve layering and offsetting those nets so as to at least slow the atoms down as they path through the mesh.

You can regenerate hydrogen in flight by (1) condensing water from the air and (2) electrolyzing it. It's so much cheaper and more replenishable than helium that it allows much more flexibility and, ultimately, flight safety, because it can be vented in an overpressure emergency without any hesitation.

I wonder how strong a magnetic field would be need to be to prevent leakage in an airship using ionized hydrogen as a lifting gas.

Assuming that the airship can sustain a 10K C hydrogen plasma, of course.

Maybe just at the boundary.

I've thought about that one off and on for a while too. Maybe something like an thin wire electromagnetic mesh as the inner layer of the envelope but I'm guessing no one has tried that at scale because the math says no.

Most likely you either have to pump a lot of power through the mesh to get field coverage enough to reliably bounce atoms away from the skin or you have to make the wire mesh so dense that you've basically got a layer of copper as your envelope and are therefore far too heavy to lift off.

It seems like too obvious an option to have simply been missed over the decades.

Still, I have to wonder if someone will invent a way to coat a string of fabric in like 1nm thick copper film. Or maybe graphene will save this idea too.

So... you want to replace flammable hydrogen with... ionized hydrogen. Hm.

Ionized hydrogen is basically acid without the water.

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