As skeptics of the Vacuum Balloon Holy Grail will have you know, buoyancy is not only weight, but displacement of medium. A vacuum balloon replaces air at atmospheric pressure with nothing, and from this buoyant force (760 mm Hg) one must subtract the weight of the balloon frame - hefty because of the difficulty of excluding pressurized atmosphere. Hydrogen replaces air at atmospheric pressure with a much lighter gas at atmospheric pressure, which is much easier to contain.
Hydrogen is the lightest gas because hydrogen is atomic number 1, so hydrogen molecules don't weight much. But consider oil - oil molecules are much bigger than water, but oil is less dense because oil molecules pack less tightly. What is needed to improve on hydrogen is a gas where the molecules pack less tightly.
I propose that ultralift balloons be filled with Ionic Gas. This initially neutral mix of two molecules would turn into a charged mix as one of the ions reacted with and was (permanently) bound to small sponges on the balloon's interior surface. The remaining Lift Ions would repel others of its ilk, increasing the volume which it occupied. The balloon would swell, gaining volume as its mass remained the same. Depending on the charge of the Lift Ion filling it, these balloons could be huge, but nearly empty, approaching the perfection of the vacuum balloon and suitable for all the same applications.
Lift could be controlled by injecting small quanities of the ionic opposite (Sink Ions), which would mop up the Lift Ions temporarily, rendering them neutral and decreasing the volume and lift of the balloon.-- bungston, Jun 30 2003 why ions don't expand water http://users.rcn.co.../HydrogenBonds.htmlfor bungston [hob, Oct 04 2004, last modified Oct 06 2004] Cold plasma http://www.odu.edu/...est/ColdPlasma.htmlFrustratingly vague. Better links welcome. [bungston, Oct 04 2004, last modified Oct 06 2004] Ionic liquids http://en.wikipedia.org/wiki/Ionic_liquidI had never heard of these before. Very cool. I am not sure they would make better gases for balloon use than hydrogen. [bungston, Aug 01 2007] Things that make you go hmmmm.....-- RayfordSteele, Jun 30 2003 Oh, I was interested in knowing more about Ironic Gas.-- bristolz, Jun 30 2003 Use a metallized mylar balloon, attach to a Van de Graff generator to give it a static charge, and you have it.
Right now, I'm not going to calculate the voltage necessary to maintain turgor against ambient atmosphere. I predict, though, it'll be largely unsuitable for use near electrical storms.-- lurch, Jul 01 2003 // turgor //
Haven't seen that word in a long time. +-- saker, Jul 01 2003 "Mummy, my ionic gas lift vehicle keeps zapping things"
"Coat it in a thin ceramic layer and it'll be fine dear"
There's an idea within a idea... using electrostatic repulsion to make materials hold their shape....-- venomx, Jul 01 2003 Great Idea - the perfect lift medium for a Hullaballoon methinks. However, If you have a stretchy balloon, then you also have to overcome the force exerted by the balloon trying to return to it's original shape. If you had a fixed size bag to fill with ionic gas, that's be one less force to overcome - although it would be expandable.-- goff, Jul 01 2003 Hey, way to get hit by lightning! Duh.
(Also, remember that if you statically charge a container of anything, all the charge migrates to the outside surface. Also remember that a gas containing only hydrogen ions is a plasma, which is moderately difficult to contain at room temperatures.)-- DrCurry, Jul 01 2003 Excellent idea - except for the enormous charge that will build up if the particles are charged enough to support a large balloon. At best, the charge will slowly dissipate, at worst you will ground or spark.
Instead, you should consider thermally energising the particles. This will likewise reduce the density of the gas, but in a safe and controllable manner. A kerosene burner might do the trick.
I believe Joseph and Ettienne Montgolfier have begun some rather advanced experimentation involving a device that actually flew and carried a sheep, a duck, and a rooster in September '83.-- FloridaManatee, Jul 01 2003 ydevor: two things you have overlooked: the charge in a container migrates to its outside surface (not much of a problem in and of itself, of course); and the relative strength of the ionic repulsion vs. atmospheric pressure. Ain't no way you can make a vacuum balloon this way (except in a near vacuum). If you doubt me, attach a balloon to a Van der Graaf generator and see what happens.-- DrCurry, Jul 02 2003 Still a wonderfully half-baked idea though. If it were fully thought through, it wouldn't be here would it?-- goff, Jul 02 2003 The electrostatic performance of the material you choose for the envelope is going to be crucial here. With any kind of conductivity at all, the increasing postential across the membrane will tend to dissipate. I'm not sure what the effect of a perfect insulator would be, although it seems reminiscent of a gigantic capacitor or Leyden Jar.
The solution that occurs to me is that the fabric will need to continously gather electrons and channel them across its surface to a gathering point. Basically you'd need to create a continuous current, so you'd need to supply an enormous amount of electrical flow to keep the process going.
This is going to need to be generated, and possibly stored, and that means weight. I'd imagine that, all things being equal and the laws of thermodynamics not being subject to temporary local suspension, the amount of gear you'd have to haul would more than offset the gain in bouyancy.
I imagine that making the envelope of a photovoltaic polymer might work. The action of sunlight would force electrons in one direction across the membrane. Then perhaps some kind of conductive cilia could distribute the -charge into the surrounding air.
Actually you'd probably want to dump the -charge some way from the balloon, so a trailing cable with a clump of cilia hanging at the end might work.
But in how many ways does this thing start to sound like one huge lighting attractor? And full of toasty, flammable hydrogen too.
Further vague objections I have concern the mechanical strain on the envelope caused by electromagnetic forces... but I don't quite have a handle on that yet.
Gets a pastry from me for originality. And because it seems like it kinda might work.
It reminds me of one I've been meaning to post...-- BunsenHoneydew, Jul 02 2003 Looks like [ydeavor] was scared off before I got to read his schemes. I have been reading about cold plasma - which it looks like is what the ionized gas in this balloon would be. I am ignorant about this stuff. Is this the plasma in all those plasma clocks and other toys on the HB? I will hook on a link if I can find a good one, but so far they are pretty superficial treatments.
Most of these cold plasmas look pretty reactive (example: fluorine ions) and although they exist long enough to be used industrially, I am not sure if cold plasmas can be contained. If so, generation of cold plasma for the balloon would make a lot more sense that trying to generate it in the balloon via a chemical reaction, which would quickly become energetically unfavorable.
Finally: [hob's] link. Maybe I really am dumb, but I see no mention of ions on that page.-- bungston, Jul 02 2003 bungston, that link is not the best, but my point was that water molecules already carry both positive and negative charges, which contribute to the cohesiveness of water as a liquid. They also readily dissociate and recombine. There is always an OH- or the negative pole of an H2O around to attract the H+'s.
The point of DrCurry's blunt response was that "acidic water" does not mean water plus extra H+ ions; it means water plus H+ ions plus the negatively charged remnants of the molecules the H's disassociated from. Acidic solutions do not have a net positive charge, nor do basic solutions have a net negative charge.-- hob, Jul 02 2003 I better stop now before all this dust on my college chemistry textbook gets me sneezing.-- hob, Jul 02 2003 If positronium was stable it would make for the lightest gas possible.
Alas that much matter and antimatter together would just be a big bomb.-- talldave, Jul 03 2003 Just a quick ponderance. A balloon has an elastic force when inflated trying the get back to its deflated shape. If you coat a balloon inflated to twice the desired size of your final balloon, then pop the original balloon (like doing a papier mache head), is there a material that would shrink when you removed the air inside it, but have an elastic force trying to pull it back to its full size? If there is, you've got your elf a no-airship.-- marklar, Aug 02 2007 marklar, put this in a sepparate idea, so everyone can bone you how come it wont work.-- pashute, May 21 2008 random, halfbakery