[Airships] Your suggestions how to bring a Zeppelin into the Atmosphere of Jupiter?

[MedwedianPresident]

Post your suggestions how to bring a Airship into the Atmosphere of a Gas Giant! And don't forgot to TRY it on Jool or Eve!

[Thiel]

I wouldn't. The wind would tear it apart no matter how carefully it was done.

[Kryten]

That wouldn't be an issue with a high-altitude craft, but then you run into the issue of working out how the heck you make something float when it's already in the lightest possible gas at low pressure.

[mcirish3]

That wouldn't be an issue with a high-altitude craft, but then you run into the issue of working out how the heck you make something float when it's already in the lightest possible gas at low pressure.

The outer shell needs to be very strong as well as very incomprehensible if sufficiently incompressible should float once the density of the craft is less than the density of the air around it. Very much a tough engineering challenge, but as long its decent speed was slow enough should be no problem with getting one there.

[RedDwarfIV]

Ahem.

You may be forgetting the simplest option. A vacuum balloon has around 15% greater bouyancy than a hydrogen balloon. Normally, it would be difficult to build one of these in Earth atmosphere because it's simply too difficult to remmove that much air from a space. However, if you are already in space, you need only keep atmosphere out, provided you can, of course, slow your ship enough not to get destroyed by atmospheric entry.

[Highlad]

And then you have to worry about the magnetosphere.

I'm making a platform on jool with the 'airships to other planets' mod. Its pretty cool. One bad thing is that my poor kerbals cant stand up because it is not perfectly stationary.

[Fuzzy Dunlop]

That wouldn't be an issue with a high-altitude craft, but then you run into the issue of working out how the heck you make something float when it's already in the lightest possible gas at low pressure.

Heat it? how hot is jupiter anyway?

[Kerbface]

Heat it? how hot is jupiter anyway?

Jupiter is very cold, but because of the lack of pressure, it's a gas up the top of the atmosphere. I think the vacuum idea sounds much more efficient than heating, honestly I don't see any disadvantages when you're already close to a vaccuum.

[K^2]

Ahem.

You may be forgetting the simplest option. A vacuum balloon has around 15% greater bouyancy than a hydrogen balloon. Normally, it would be difficult to build one of these in Earth atmosphere because it's simply too difficult to remmove that much air from a space. However, if you are already in space, you need only keep atmosphere out, provided you can, of course, slow your ship enough not to get destroyed by atmospheric entry.

I'm not sure you understand how pressure and buoyancy work. Increasing thickness increases weight by same amount that it increases strength of the balloon. At the same time, pressure increases stress by the same amount that it increases buoyancy. In other words, even if the pressure is lower, all that it means is that you have that much less lift, and have to make the thing that much lighter, losing just as much strength to fight the said pressure.

It is very near physically impossible to make a vacuum balloon that would work in nitrogen-oxygen mixture. It is physically impossible to build it out of a single shell, but there are approaches with fractal structure that work on paper. In practice, it has never been done. Air provides the same amount of pressure, and therefore stress, as hydrogen would. But the later provides a lot less buoyant lift.

A vacuum balloon that can float in hydrogen is, in fact, impossible to construct.

So your only option for floating in Jupiter's atmosphere is a "hot" hydrogen balloon. That will not provide nearly as much lift as helium does on Earth, so you'll end up with an absurdly large and delicate structure that will not be able to float anywhere near as high, and we're right back to being torn by the winds.

[Scotius]

Arthur C. Clarke wrote a short story titled "A Meeting with Medusa." Basically it described a mission of nuclear-heated baloon piloted by a cyborg into upper layers of Jovian atmosphere. It's a good read, with interesting descriptions of hypothetical organisms living there.

[shadowmane]

I don't think Jupiter would be a good target for such a mission. However, figuring out how to get a probe to slow down enough to deploy a blimp in the atmosphere of Venus can be done. I believe the Soviets did it twice.

[Stochasty]

It is very near physically impossible to make a vacuum balloon that would work in nitrogen-oxygen mixture. It is physically impossible to build it out of a single shell, but there are approaches with fractal structure that work on paper. In practice, it has never been done. Air provides the same amount of pressure, and therefore stress, as hydrogen would. But the later provides a lot less buoyant lift.

K^2, would you happen to have a reference handy for the fractal vacuum balloon?

I'm actually a little surprised that weight and strength scale at the same rate in this context. I'd have expected a 2/3rds power law, giving smaller craft proportionally more buoyancy for the same strength (for the same reason that ants can lift proportionally much more weight than humans).

Edit: Nevermind; I just worked it out. It's because compressive force over buoyancy has the same 2/3rds scaling law that compressive strength over weight does.

Edited May 9, 2013 by Stochasty

[Nuke]

a constant 2.5 gs will likely suck. you are better off doing this kinda thing on saturn, neptune, or uranus.

[Stochasty]

Actually, the strength of gravity doesn't matter for balloons, since it affects the weight of the displaced air equally to the weight of the balloon; they'll always float at the level at which the densities are equal, regardless of the local gravitational strength. What matters is the composition of the atmosphere.

[Nuke]

i was thinking more in terms of crew comfort, assuming the ship was manned. in the case of an unmanned craft, you still have structural loads that need to be considered, load bearing structures need to be beefed up more in jupiter than on another gas giant.

Edited May 9, 2013 by Nuke

[falofonos]

Crew comfort would be a problem in Jupiter's atmosphere, the radiation shielding to keep them alive would likely out mass any buoyancy your vacuum balloon could provide.

[magnemoe]

Arthur C. Clarke wrote a short story titled "A Meeting with Medusa." Basically it described a mission of nuclear-heated baloon piloted by a cyborg into upper layers of Jovian atmosphere. It's a good read, with interesting descriptions of hypothetical organisms living there.

Yes, he also used an nuclear ramjet to get out from Jupiter again. Probably used that one to generate heating for the balloon to, this has some issues like the configuration of the intake so this work from low speed up to escape speed.

An simple balloon probe should work well, but you would be under time limit, inflate and heat the balloon before going to deep.

In KSP I have used balloons to get out of both Eve and Jool, sendt down an probe to try to mine for kerthane on Jool, it did not work, Planing of doing an large Eve mission with an airship. My first mission used the balloons to get up to 20km, but with an electrical propel I would have an airship.

[SunJumper]

Have you thought about a nuclear fusion device that sucks in the hydrogen at the top, and expels hot helium out of the bottom? Any structure would probably have to be a torus to avoid being in the exhaust, but still...

You could even also hang a device to reclaim a little bit of the helium, to use as helium is used. Obviously not all of it, but 1% can't hurt.

[K^2]

K^2, would you happen to have a reference handy for the fractal vacuum balloon?

[...]

Edit: Nevermind; I just worked it out. It's because compressive force over buoyancy has the same 2/3rds scaling law that compressive strength over weight does.

Precisely. Which means the only way to get around that is inhomogeneous structure. A fractal in 3D does not necessarily scale as a 3D object, which means it can have a different scaling law for strength to weight. And I have seen some patents, along the lines of carbon fiber or even aluminum alloy skeleton with a mylar skin, but I don't have any links saved.