Well one of the challenges of both helium and hydrogen is that they are really very small molecules, and they tend to slip out through the smallest gaps. This is why the metalized aluminum skin was on the Hindenberg in the first place, and ultimately doomed it.
Lighter than air solids have the issue that if you remove the air from the spaces in those solids and try to hold it out you create a pressure differential that crushes them.
There was some speculation that given an ability to precisely manipulate carbon you could build dodecahedrons out of pentagons of diamond in a vacuum and then when you removed them from the vacuum they would have a net density lower than that of air, but the density ratio is so small (assuming you could build them) that you'r talking about a massive airship that ascends to maybe 3,000' on a cold day.
Exploiting air density is a challenging path that has not had much success of late.
Comments
Well one of the challenges of both helium and hydrogen is that they are really very small molecules, and they tend to slip out through the smallest gaps. This is why the metalized aluminum skin was on the Hindenberg in the first place, and ultimately doomed it.
Lighter than air solids have the issue that if you remove the air from the spaces in those solids and try to hold it out you create a pressure differential that crushes them.
There was some speculation that given an ability to precisely manipulate carbon you could build dodecahedrons out of pentagons of diamond in a vacuum and then when you removed them from the vacuum they would have a net density lower than that of air, but the density ratio is so small (assuming you could build them) that you'r talking about a massive airship that ascends to maybe 3,000' on a cold day.
Exploiting air density is a challenging path that has not had much success of late.