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As it is well known, a vacuum balloon using the materials we have at our disposal is not possible, because of the sheer force they have to resist from the air outside.

I asked this question on Physics stack exchange and haven't got an answer yet.

I have an idea and I want to know if there is anything that makes it impossible.

  1. Build a balloon out of graphene which is very light and it is conductive too.
  2. Since graphene is not airtight, cover graphene (that is not yet inflated) with a good electrical insulator which is also airtight.
  3. Now make the graphene store electric charge.
  4. This would exert force from inside as the electric charges on the graphene repel each other.
  5. This causes the balloon to inflate while having a vacuum inside.

Now my question is there any theoretical problems (not engineering problems) with this model?

706Astor
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Moj
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6 Answers6

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Let's completely neglect material strength and just consider air pressure and the force from electric charges.

Air pressure is 101325 Pascals, or 101325 Newtons per square meter. That means that the net force on one square meter of material must be equal to that force in order to prevent the balloon from breaking.

I'm completely abusing notation here, but let's give the material a charge density of $\mathbb{Q}$ Coulombs per square meter - in other words, on one square meter of material lies $Q$ Coulombs. The balloon has a radius of $r$, meaning that (assuming it's a sphere) the surface area is $4 \pi r^2$, and the total charge is $4 \pi r^2\mathbb{Q}$

The force on this one square meter from the electric charge is, therefore, $$F=k\frac{4 \pi r^2 \mathbb{Q}Q}{r^2}=4 \pi k \mathbb{Q}Q$$ For the balloon to work, this force must be equal to 101325 Newtons. This means that $\mathbb{Q} \approx 9.47 \times 10^{-4}$ Coulombs per square meter. Not too bad. Seems plausible.

HDE 226868
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I think it is (theoretically) possible, but it didn't work when I tried. My main problem was that I didn't have a good way of stopping the required high charge from ionizing the surrounding air.

I accidentally posted a duplicate question on the Physics Forum...

Community
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Chandran Goodchild
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I had a similar question then realized that I could use graphine to do this. Now I think that if the airtight sealer was strong enough, instead of creating a vacuum in the way you described, you could instead make a collapsible frame of graphine inside as well, that would lock in the way your knee does. Then you could expand the frame with servo motors and collapse it that way as well. I’m going to try to use this idea to create a statolite.

Blue Herring
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On of the problems with vacuum balloons is that the potential gains over using hydrogen or helium are actually pretty small, something like 10%. On the other hand the difference is stress between containing a gat at or around ambient pressure and containing a vacuum safely are orders of magnitude greater.

This is magnified by the fact that a gas filled balloon can afford to be a bit leaky as the pressure difference between inside and outside is small gas loss will be slow unless you have a really big hole. In the case of a vacuum container however any leak will result in rapid loss of vacuum and may even cause a catastrophic failure of the structure.

The net result of this is that whatever exotic materials you can develop you will still be better off using them as the skin of a gas filled balloon as the fundamental performance trade off still applies.

TO put it another way, while something like graphene might make a vacuum balloon possible the chances are that a helium/hydrogen balloon will still be better.

Chris Johns
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Make a reverse Farnsworth Fusor! A little helium gas in a mylar balloon with special considerations made to polarize the metal interior as a capacitor with the ground being your gas feed tube! The plasma will accelerate from the ground as positive helium nuclei to neutralize on the negative balloon walls. Because electrons streaming to ground act with little force and the ground wire can be insulated until a plasma stream develops you don't have to worry about the electrostatic attraction to ground overcoming the strong negative plates self repulsion and the strong helium plasma pressure!

Taylor
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If it was electrically "inflated" in near earth orbit then allowed to float down to equilibrium to be retrieved would make the forces during inflation negligible. I've been pondering the vacuum balloon since I was about 10 and I always come back to the idea the it would have to be constructed in a near vacuum. However I always thought of the rigid shell designs or braced designs this charged graphene idea seems like what I was missing

David Vance
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