Question Plasma/vacuum balloon
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RisingFury
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Yes. Keep in mind that buoyancy is provided by the displaced medium and is countered by weight. Weight of lifting gas included...
The reason we don't see vacuum or plasma balloons is because they're difficult to construct. It's easy to fill a latex balloon with Hydrogen or Helium, because you have very little pressure and temperature difference between the inside and outside of the balloon.
But if you want a vacuum balloon, you'll need strong walls for the balloon not to "cave in". Those are usually heavy...
With a plasma balloon you'd need a well insulated balloon, cooling of walls and heating of plasma...
The reason we don't see vacuum or plasma balloons is because they're difficult to construct. It's easy to fill a latex balloon with Hydrogen or Helium, because you have very little pressure and temperature difference between the inside and outside of the balloon.
But if you want a vacuum balloon, you'll need strong walls for the balloon not to "cave in". Those are usually heavy...
With a plasma balloon you'd need a well insulated balloon, cooling of walls and heating of plasma...
HarvesteR
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Yep, in fact, in the book "Tarzan at the Earth's Core", by Edgar Rice Burroughs, they take on a journey to Pellucidar, a world inside the hollow Earth, by means of an airship equipped with vacuum tanks, instead of helium or hydrogen... The "O-220", IIRC.
It was made of "Harbenite"... a fictional metal hard yet light enough to construct such a thing
It's 1920's fiction... but quite cool anyways!
Cheers
It was made of "Harbenite"... a fictional metal hard yet light enough to construct such a thing
It's 1920's fiction... but quite cool anyways!
Cheers
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Rtyh-12
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Of course, it is possible, but (as RisingFury said) it's waaaaaaaay too expensive. Especially the plasma one, where you also have to consider that plasma is very very very hot... but you can also fill it with very light gases.
Jarvitä
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Not that convenient either...air isn't that heavy to begin with. You'd need a 1.2kg vessel holding a cubic metre of vacuum just to achieve neutral buoyancy at surface-level pressure. That doesn't strike me as achievable with current materials.
[ame="http://en.wikipedia.org/wiki/Vacuum_airship"]Vacuum airship - Wikipedia, the free encyclopedia[/ame]
Interesting to note from that is that hydrogen is only 7% less efficient than a vacuum and helium is only 14% less efficient than a vacuum in terms of lifting power. Given the significantly reduced amount of infrastructure required to support a bubble of helium than a bubble of vacuum, 14% reduced volume efficiency seems perfectly acceptable.
I briefly considered that it might be better to do this sort of thing on another planet with a thinner atmosphere, but since the helium filler is usually added to ambient atmospheric pressure anyway, it won't make a difference.
Interesting to note from that is that hydrogen is only 7% less efficient than a vacuum and helium is only 14% less efficient than a vacuum in terms of lifting power. Given the significantly reduced amount of infrastructure required to support a bubble of helium than a bubble of vacuum, 14% reduced volume efficiency seems perfectly acceptable.
I briefly considered that it might be better to do this sort of thing on another planet with a thinner atmosphere, but since the helium filler is usually added to ambient atmospheric pressure anyway, it won't make a difference.
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HarvesteR
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Wouldn't it be the other way around? If I understand buoyancy correctly, the heavier the external fluid, the more lifting power you have for any given volume of displacement (while using the same internal fluid)...
That would mean an airship (be it vacuum or conventional) would be very much less efficient on a thinner atmosphere, as on Mars, for example, since the density differential for the insides and the outsides is smaller.
Cheers
That would mean an airship (be it vacuum or conventional) would be very much less efficient on a thinner atmosphere, as on Mars, for example, since the density differential for the insides and the outsides is smaller.
Cheers
Rtyh-12
Member
Indeed. If you used it to go to Titan... well, because of the thick atmosphere and low gravity, it would be air sailor's paradise.
Also, I saw a documentary where they said it would be possible to fill a very big balloon with air (yes, air) and let it float in Venus' high atmosphere, where the temperatures are similar to Earth's. (about 50 km)
Also, I saw a documentary where they said it would be possible to fill a very big balloon with air (yes, air) and let it float in Venus' high atmosphere, where the temperatures are similar to Earth's. (about 50 km)
RisingFury
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Artlav
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I keep dreaming about having a point force field, expanding it to a big sphere, throwing a net around and having an instant balloon.
Easy control, compact storage, maximum efficiency.
It's 21st century, dammit! Where are all the fun stuff from the future?
TSPenguin
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If you have a forcefield and still need a net for this, you are doing your pseudo science wrong!
Artlav
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Rules of evil overlord specifically state that forcefield generators should be located within the forcefield they generate, and that's the type i'll order. So no way of tying the basket to the generator.
Right, I wasn't talking about the relative efficiency between blimps on Earth and blimps on Mars, but rather the relative efficiency between vacuum blimps and helium blimps on Mars--which I suspect would be the same as the relative efficiency between vaccum blimps and helium blimps on Earth.
Although you would need less structure for a vacuum blimp on a thinner-atmosphere world, I still don't think it would be feasible.
The problem is that all of your 14% goes away with the additional structure required to support a vacuum container of a size to be interesting. This isn't the case with hydrogen, which is why they used to use hydrogen in blimps, but it was experimentally determined that the safety considerations outweighed the efficiency gains.
