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# Vacuum Blimp

Using high pressure frames and such
 (+3, -6) [vote for, against]

Okay, I think this may have been mentioned before, but... have you ever shaken up a bottle of coke or Lemonade? If you have you'll notice how strong the bottle gets. It's a simple step from there to use that strength for strong lightweight construction, Vacuum blimps included. If pressurized with something such as Hydrogen or Helium, the frame could be made even more lightweight.
 — Selky, Dec 28 2008

/I suggest pressurizing with vacuum instead./ - Pressurizing with vacuum seems like an oxymoron. The above link is my idea of how it might be done. [bungston, Dec 29 2008]

Vacuum Balloon Inflated_20Shell_20for_20Vacuum_20Balloon
Half Baked [mylodon, Jan 05 2009]

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 So, the idea is to use pressurized tubes as the frame for a blimp?

Pressurized struts are not a good (though possibly not an original) idea. However, I'm pretty sure that even they won't give you enough strength/weight ratio to enable a vacuum blimp.
 — MaxwellBuchanan, Dec 28 2008

 — Voice, Dec 29 2008

 I don't see any details on the vacuum blimp.

 However, I can assure you that part of the reason the pressurized soda can is so strong is because of it's shape.

 A "blimp," or in this case, a dirigible/zepplin, for aerodynamic reasons, must be shaped something like a football. to make it lift, something lighter than the air around it goes into the "bag." In this case, vacuum, rather than a lifting gas.

 Now, the reason the coke bottle gets hard, is because of a pressure differential. With a vacuum blimp, that pressure differential is in the opposite direction: The pressure on the coke can is higher on the outside. the pressure on a vacuum blimp is higher on the inside.

 A high pressure frame would need to stiffen the material like a coke can does, but would then need to be double pressure-stiffened to resist the inherent crushing force of the vacuum in the blimp.

 Pressurizing with hydrogen or helium is likely to be more or less useless, as they cease to be lifting gasses when they are pressurized to the point of being denser than air. I suggest pressurizing with vacuum instead.

 As an interesting aside, someone has suggested using fullerines as lifting "gas." Normal fullerien balls are about C60, and either have one metal, or nothing in their core. however, as a geodesic dome formation, larger fullerine balls might be possible. It was suggested that the C240, and larger balls would, by the nature of their carbon-carbon bonded exterior, be impermeable to any objects, and if rigid should therefore contain hard vacuum inside them. their size ought then to make them a "lifting gas" far less dense (and therfore far more potent) than even hydrogen, almost totally inert, and (some day) easily synthesized in the laboratory (unlike helium, which must be harvested as a byproduct of natural gas, or generated through fusion of hydrogen.)

I'd post the C240 lifting gas as an idea, except I know it's not original, and as the fullerine tubes are enormously flexible, I suspect the larger fullerine "spheres" may look something like a popped beach ball.
 — ye_river_xiv, Dec 29 2008

 //It was suggested that the C240...should therefore contain hard vacuum inside them. their size ought then to make them a "lifting gas" far less dense ...than even hydrogen//

Actually not. If you could operate a balloon at a high enough temperature so that C240 was a gas, it would have a density 1,440 times that of H2 and 99 times that of air. The "hard vacuum" inside makes no difference. After all, the space between hydrogen molecules is also a hard vacuum.
 — ldischler, Dec 29 2008

 Heating thr fullerene spheres in question until they become a gas should not be necessary.

 Hydrogen and helium work as lifting gasses because the energy of the particles forces the nuclei apart. A bag full of it can therefore displace the denser air around it.

 Fullerine balls of this size would indeed be far more massive than air, or hydrogen... so is a zeppelin. The zeppelin stays afloat because it's mass is less than a similar volume of air. The theory goes that the fullerine balls have so much space inside them because of the size of the molecule, that they too would have a mass/volume ratio less than atmospheric air. In effect, they would each be tiny "vacuum baloons," with a frame supported by airtight carbon-carbon bonds. I suppose they would actually more properly be considered a "lifting molecule," as their solid nature is the reason they might work, and not any gaseous state they may or may not be in.

 In theory, if the structure is rigid, and airtight, and has a mass/volume ratio less than air, it should float. I didn't do the math to find out whether or not a carbon fullerine sphere of any size might have the proper ratio, but in theory, if it is indeed rigid, and can indeed form a suitably sized airtight sphere, it should work.

I don't think using vacuum as a lifting agenthas any other way it might work at all... and I doubt that the spheres would stay both rigid and airtight.
 — ye_river_xiv, Dec 31 2008

 //Heating thr fullerene spheres in question until they become a gas should not be necessary . . . //

 //I didn't do the math to find out whether or not a carbon fullerine sphere of any size might have the proper ratio . . . //

So you think a solid fullerite would have low enough density to float? C60 has a reported density of 1.64 g/cc. Air has an STP density of 0.0012 g/cc—more than a thousand times less. Doubling the diameter of the fullerene molecule takes you to C240. It's 4 times heavier and has 8 times the volume, so its density should be around .8 g/cc. That's light enough to float on water, but orders of magnitude short of floating in air. As you go even larger, the sphere should become unstable and collapse like an uninflated balloon, making it impossible to decrease the density further.
 — ldischler, Dec 31 2008

The easy way to do this is to fill the blimp with steam. when this condenses: vacuum.usually the blimp or coke bottle implodes.
 — giligamesh, Jan 02 2009

 //So you think a solid fullerite would have low enough density to float? C60 has a reported density of 1.64 g/cc. Air has an STP density of 0.0012 g/cc—more than a thousand times less. Doubling the diameter of the fullerene molecule takes you to C240. It's 4 times heavier and has 8 times the volume, so its density should be around .8 g/cc. That's light enough to float on water, but orders of magnitude short of floating in air. As you go even larger, the sphere should become unstable and collapse like an uninflated balloon, making it impossible to decrease the density further.//

 No, I don't think a solid fullerite would be able to float. Someone else does.

 You'll notice my earlier post, saying:

 //I'd post the C240 lifting gas as an idea, except I know it's not original, and as the fullerine tubes are enormously flexible, I suspect the larger fullerine "spheres" may look something like a popped beach ball.//

I'm glad the two of us came to the same conclusions. Platonic science would be proud.
 — ye_river_xiv, Jan 04 2009

 // I think this may have been mentioned before // Yes it was.

For any bucky-ball like structure to contain a vaccum it would have to be undisturbed and remain a perfect spheroid. Any heat transfer with the sides of the vessel would cause disturbance with the bucky spheres and collapse the the fullerenes and the ship would sink. This is the equivalent of experiment where a can is heated, then a cap is placed on the lid. When the can cools, a simple flick of the finger causes the collapse of the can.
 — mylodon, Jan 05 2009

 Why not rely on moderate pressure of a light gas (such as He) to keep the frame aloft? You'll never achieve the strength/weight. Do the math: Air at atmospheric pressure is 1.2 kg/m^3 and provides about 101325 N/m^2 of force. Those two figures scale with eachother as pressure goes up (within a reasonable range). Then, you still have to fight atmospheric pressure. If you put Hydrogen into the struts, you might as well use it in the whole craft.

To get the density down you could heat the air. Oh... wait... Yeah, I think that's been done once or twice. You could also use a lighter gas such as.... perhaps.... Hydrogen? No, that didn't work out so well. Helium? Well, that's quite expensive and frankly non-renewable, so I guess that's out for most transport applications.
 — kevinthenerd, Jan 07 2009

 //There must be a sweet spot between a vacuum and atmospheric pressure though where materials like aerogel or bucky beach balls would work// Yes there is! I will give you a clue, it varies with altitude (that is distance away fron the overriding gravitational force). Another clue: There must be an average of velocities that are in a direction radially (from the gravitation source) greater than the average velocity of the substance you want to "float upon" That's right, specific density. If something is less dense that something else it will rise. Well then, is density some kind of add atomic mass then subtract perfect vacuum? NO, well I hope to God not! Specific gravity, and that's why I don't like *density* a whole lot, has more to do with kinetic energy (KE), than it does with density per se. Of course density plays a roll, but only with momentum and the energy of the "feild". Lots of "heavy" materials have vast vacuums within them, and I am glad they don't float off into the distance with my wife's ring finger attached. Equating bouancy with a vacuum is analagous to equating light with an absence of darkness. It is not observably correct.

 Individual buckyballs, of whatever configuration are surprisingly un-gasseous. You could take their presumed contained vacuum and scale it up all you want. The fuckers are just not bouncing around enough. And although they could move around alot, they just fucking don't. KE, momentum, and all that. Fortunately the gas laws do not take contained vacuum into account, if the did, by now the sun (and all other suns) would have spread across most of the milky way (and universe) and even if that did not happen *we* certainly would not be in an argument contemplating such an event.

 Now take another carbon configuration. I dunno, maybe one carbon and two oxygens, or even one oxygen. Sorry, did you say carbon 12 and oxygen 16? Surprisingly gasseous. Surprisingly heavier than a similar Carbon 3.

 Is it because it contains more vaccum? That would be nice. But no. It is a gas and its general velocity, given all directions is higher than its general downward force.

 I don't want to get harsh, but listen fuckers, vacuums don't suck anything into orbit. No matter how much vacuum you stuff into a vesicle, it won't go up. Unless the vesicle has a mean entropy greater than those that surround it.

 I am going a bit further than [ld] on this one. It is got fuckoll to do with density, and more to do with mean KE, whether something floats or not.

 I grant fully that this works with liquid displacements. But gas is not such a beast.

Did I just say: Butt gas is not such a beast?
 — 4whom, Jan 07 2009

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