Solid Smoke With Helium?

Are you referring to aerogels?

Ok,

I will continue. No you can't.

A quote from the below cited source,

Would it be possible to create aerogel lighter than air by using helium instead of air?

Aerogel cannot be made less dense than air by filling it with helium. You might be able to make it less dense than the surrounding atmosphere by filling the aerogel with helium and then placing it in an atmosphere of radon or possibly xenon.

Stardust - Frequently Asked Questions

Superficially, the idea is quite attractive. That well-known reliable source Wikipedia reports the density of a silica aerogel as 1.9 mg/cm3 when air-filled and 1 mg/cm3 when evacuated.

http://en.wikipedia.org/wiki/Aerogel

The density off air is 1.2 mg/cm3, so this calculates to a gas space of 0.75% of the material, which, when filled with helium, would give a density of 1.13 mg/cm3, less than that of air. Where this falls down, unfortunately, is that aerogels are extremely porous, which makes them unsuitable as a balloon membrane, let alone as a gas retainer.

What about this metallic lattice encased in aerogel filled with hydrogen?

I think it would depend on the size and shape of the form it took.Steel does not float, but a ship will, because of it's displacement.A blimp filled with aerogel and helium could be made with a thinner structural skin, and therefor be made larger than current practical limitations. Leaks due to damage would be of minor concern.It would take catastrophic damage to bring one down.It would take a certain amount of free helium to provide lift, and that could be used also as ballast control.

A large sphere creates an updraft, due to it's shape, and this could assist in the lift.I mean very large: 5 miles diameter of more for this to be significant.Then a small differential temperature between inside/outside would provide tremendous lift.

Want to move a city? No problem.

You mean like this?

http://inhabitat.com/high-flying-algae-airships-are-self-sufficient-airborne-cities/

This looks pretty strange, the Millennium airship?

It's an interesting idea.

Helium atoms are the smallest and helium is extremely hard to contain. My guess is that it would diffuse out in a short time. Hydrogen molecules (H₂) are much larger and half as heavy, and would be easier to contain.

Aerogel is currently very expensive, and a breakthrough in manufacturing would be needed to make it economically feasible.

Yes, you can make a solid balloon of aerogel and fill it with helium - as long as you cover the outside with a thin film, maybe thin metal.

Bear in mind, Helium is a monatomic gas - it exists alone, not like H2 or O2.

This means helium is far smaller and why helium balloons go flat fast, even with metallized mylar as a cover.

Practicality = low, but doable

Has anyone considered placing the aerogel IN a helium atmosphere and then drying the aerogel? I am not sure of the entire process, but it seems as if it would absorb the surrounding atmosphere.

BTW. I gave a helium filled mylar coated balloon to my wife for Valentines Day, it looks the same as it did three weeks ago. Apparently, the quality of the mylar coating has much to do with the retention of the helium.

Dragon

How is the buoyancy of that mylar balloon? I find they lose pressure and then wrinkle up. Mylar balloons filled with air stay taught, but are not buoyant .

Often non buoyant mylar balloons are sold with air inside for economic reasons.

That balloon is still floating, quite well, actually, much to my wife's delight. The process of making those Mylar balloons is somewhat haphazard. If a process of making them were stringently controlled then the balloons would last longer.

And it would also allow containers that would withstand the embrittlement of Hydrogen for much longer.

Dragon

I think you mean metalized balloon. Mylar isn't a particularly good gas barrier and doesn't lend itself to thin film coating applications.

The quality/thickness of the metalization is what keeps the helium in the balloon.

I know, I know. Small detail. I'm just picky.

A lot of Aerogel's fantastic properties come from the fact that it has a MASSIVE surface area. Unfortunately, this also means getting it to retain gases is difficult, and with Helium, nearly impossible, as there are many ways in which the gas can work its way out of the material. Perhaps impregnating the material by vacuuming out as much oxygen, then allowing helium to displace the void within the material, then sealing it with a lightweight coating would do the trick- but helium on its own has a way of working out of containers, and finding the right material to coat it with- well, why not just make a balloon out of that material?
I imagine you are looking for structural integrity as well, answering my own question. I know some aerogels have the ability to withstand 1000% of their own weight in pressure. The density of those types is something I don't know, I guess it will take some looking up. It may not be practical to give it integrity at small scale, but at large scale it is much easier to decrease density while maintaining the structure. I know what I will be thinking about tomorrow when I should be working!

Ammonia, NH3 with a molecular weight of 17 is also good for this making of novelty and other balloons.

What with the looming shortage of helium and the short life of metallized mylar helium balloons, it makes me wonder of that long lasting balloon you have is ammonia filled.

It has a sharp smell, and is caustic in quantities.

Lifting gasses

Ammonia BalloonsHere