Can you fly a plane on a gas giant?

[awsumguy76801]

Gas giants have atmospheres, airplanes fly in the atmosphere, so can you fly a plane there? I'm not going to go into the fact that there is literally no way to land but just hypothetically on something like Neptune but warmer so the plane doesn't freeze and it's about 1G of gravity and the air is really thick which would actually make flying easier. If we actually wanted to land this plane somewhere we would need some sort of floating runway for it to land and refuel. The plane would need to pressurized but instead of being for low pressure it would be for high pressure because the gas giant's atmosphere is very high pressure so the cabin would actually have to be kept depressurized for any people to survive inside. This would be great if we ever wanted to colonize Jupiter or Saturn for whatever reason (probably to farm helium) because it could transport workers around the planet the one big problem is everyone would weight a lot and flights would literally take days because of the size of the planet. Thoughts?

Edited December 11, 2021 by awsumguy76801

[sevenperforce]

Fortunately this question has already been answered:

Full explanation here.

[JoeSchmuckatelli]

10 minutes ago, awsumguy76801 said:

Gas giants have atmospheres, airplanes fly in the atmosphere, so can you fly a planet there? I'm not going to go into the fact that there is literally no way to land but just hypothetically on something like Neptune but warmer so the plane doesn't freeze and it's about 1G of gravity and the air is really thick which would actually make flying easier. If we actually wanted to land this plane somewhere we would need some sort of floating runway for it to land and refuel. The plane would need to pressurized but instead of being for low pressure it would be for high pressure because the gas giant's atmosphere is very high pressure so the cabin would actually have to be kept depressurized for any people to survive inside. This would be great if we ever wanted to colonize Jupiter or Saturn for whatever reason (probably to farm helium) because it could transport workers around the planet the one big problem is everyone would weight a lot and flights would literally take days because of the size of the planet. Thoughts?

@mikegarrison is likely to be a good resource.  My guess is that the gravity is such that just trying to get into the atmosphere to be slow enough for actual flight would be exceedingly difficult.

[cubinator]

2 minutes ago, JoeSchmuckatelli said:

@mikegarrison is likely to be a good resource.  My guess is that the gravity is such that just trying to get into the atmosphere to be slow enough for actual flight would be exceedingly difficult.

We sent a probe into Jupiter's atmosphere. It's definitely possible.

The gas planets are all going to have really low density atmospheres, which will impact lift negatively. Flight speed or lift will have to be greater to compensate. The pressure depends on the altitude, so if you wanted to you could stay at around 1 atm. If you go too deep, the air will start to become supercritical and act more like a liquid.

[JoeSchmuckatelli]

35 minutes ago, cubinator said:

We sent a probe into Jupiter's atmosphere. It's definitely possible.

Falling is easy - falling with style? 

That's the hard part.

[mikegarrison]

Lift is proportional to density * velocity² * wing_area. If you had the thrust to overcome drag, and you could get the plane there, there is no reason you couldn't fly.

I assume there would be really severe windshear and turbulence.

[magnemoe]

1 hour ago, mikegarrison said:

Lift is proportional to density * velocity² * wing_area. If you had the thrust to overcome drag, and you could get the plane there, there is no reason you couldn't fly.

I assume there would be really severe windshear and turbulence.

Yes, xkcd is wrong here assuming your are not flying at an set attitude like one km above the surface, in that case the gas giants are far far worse than Venus.
You want an attitude with 0.5 - 2 bar and see if an electric plane could operate here. 

[RCgothic]

XKCD's not wrong. It's just using a Cessna rather than a specifically designed exoplane. Here's the full article: 

https://what-if.xkcd.com/30/

Bsically, the problem is that gas giants have very deep gravity wells as well as having an atmosphere.

Take Jupiter for example. Want to fly at a flight level where gravity =1G? That occurs at r=114000km. Jupiter's Radius? 70,000km. It's not happening.

Want to fly at the 1bar level? Gravity is 2.5Gs and so it takes roughly 3 times more power to maintain level flight than on earth. A Cessna can't maintain level flight, but a plane with more power could. Briefly.

(2.5G constantly would be extremely uncomfortable for the crew by the way.)

3x Earthly power consumption takes a toll. Want to refuel? There's nowhere to land and escaping to Low Jupiter Orbit takes 45km/s DV so basically you can't.

Resume XKCD scenario now.

Edited December 7, 2021 by RCgothic

[mikegarrison]

You guys keep talking pressure, but it's density that is actually what is important for lift.

The two are related, but not identical.

[RCgothic]

That is a fair distinction.

Jupiter's constituent gasses are less dense than Air, so at the 1bar pressure altitude there is less lift available than at the same pressure on Earth. There's also 2.4x the gravity, so the net effect is that 3x the power is required to maintain level flight.

That's not impossible for a while, and the other gas giants a bit more benign than Jupiter, but a plane would still only survive as long as it's fuel lasted, and escape isn't really possible thereafter.

A nuclear powered probe drone would probably be the best use case. Longest operational period followed by disposal to the depths.

[jimmymcgoochie]

In a gas giant, the optimal means of flight would be a hot air balloon, filled with pure hydrogen if possible, using an RTG for both power and heat. It wouldn’t be controllable in the sense of moving around under its own power, but would have some altitude control and also uses the waste heat from the RTG (over 90% of its total watt output, from what I’ve read).

[JoeSchmuckatelli]

1 hour ago, jimmymcgoochie said:

hot air balloon

Balloon or Dirigible?  Given the expected turbulence?  Balloon could sling about a science payload for a ton of fun if you don't have anything on board that gets motion sickness... but for controlled flight I'd presume you'd want something more blimp like.

[jimmymcgoochie]

20 minutes ago, JoeSchmuckatelli said:

Balloon or Dirigible?  Given the expected turbulence?  Balloon could sling about a science payload for a ton of fun if you don't have anything on board that gets motion sickness... but for controlled flight I'd presume you'd want something more blimp like.

Oh, you want humans in there!? I was really just going for atmospheric probes that you could yeet into the atmosphere, pop open the heatshield/aeroshell combo after slowing down enough and just unfurl a balloon like a parachute then use the RTG to heat it.

[RCgothic]

Balloons are also difficult. Jupiter is composed of hydrogen and helium. So you're going to displace the hydrogen and helium with what, hydrogen and helium? Zero density difference. Oh.

So it'll need to be hot hydrogen and helium, but even then the difference you can get isn't huge. And because the difference isn't a lot, you need a relatively big and mass optimised envelope even to get a low payload.

Then hydrogen has an excellent heat transfer coefficient and a mass-optimised envelope has poor insulation, so you'll be losing a lot of heat. So you need a lot of power to replace it.

Basically, you get a low payload and high power requirement. And when the power runs out you sink.

Edited December 7, 2021 by RCgothic

[FleshJeb]

If you're looking for power, you have to look at differing environmental conditions. The best one on gas giants is wind--They vary greatly with altitude.

So, you take your hot air balloon, or even a https://en.wikipedia.org/wiki/Kytoon

String a few kilometers of cable from the bottom, and attach a steerable parachute to the end. Like a https://en.wikipedia.org/wiki/Sea_anchor (i.e. another kite)

On your payload module, you put wind turbines, which power resistive heaters in your balloon. https://en.wikipedia.org/wiki/Airborne_wind_turbine

Now you have a sailable persistent platform for whatever you want to do.

Hmm... Kerballoons, Kerbal Weather Project, a modded KAS winch, and I know how to mod Breaking Ground rotors into generators...

[awsumguy76801]

this is good because if we ever create fusion reactors the helium and hydrogen in the atmospheres would be great to farm

On 12/6/2021 at 7:27 PM, JoeSchmuckatelli said:

@mikegarrison is likely to be a good resource.  My guess is that the gravity is such that just trying to get into the atmosphere to be slow enough for actual flight would be exceedingly difficult.

if this is possible nasa should consider sending a flying spacecraft any of the giant planets to explore their atmospheres imagine the photos we would get! The best target would probably be saturn because of the gravity Jupiter's is crushing but saturn is more tame. We might even be able to send a helicopter 

[NFUN]

1 hour ago, awsumguy76801 said:

this is good because if we ever create fusion reactors the helium and hydrogen in the atmospheres would be great to farm

if this is possible nasa should consider sending a flying spacecraft any of the giant planets to explore their atmospheres imagine the photos we would get! The best target would probably be saturn because of the gravity Jupiter's is crushing but saturn is more tame. We might even be able to send a helicopter 

the photos, i'd imagine, would look something like

without, of course, the people and the road and the rocks and the guardrail

[kerbiloid]

The diving bombers can fly everywhere.

Because the diving for them is still a kind of flying.

[Abel Military Services]

No planes was allowed on gas giants. 

You can drive a submarine. 

[kerbiloid]

A winged submarine having dived enough deep into a gas giant, becomes a plane.

[Nuke]

subs technically have control surfaces. 

though i think you would make crush depth before you found any useful buoyancy. 

[kerbiloid]

1 hour ago, Nuke said:

though i think you would make crush depth before you found any useful buoyancy. 

Just moar booster to make the lift force.

A subgas winged rocket submarine.

[RyanRising]

On 12/9/2021 at 9:11 PM, NFUN said:

the photos, i'd imagine, would look something like

without, of course, the people and the road and the rocks and the guardrail

Perhaps, but there must be some spectacular cloud banks before you get down to where it’s all obscured.

Not that I’d volunteer to go down with the probe, mind you.

[Maria Sirona]

In the right part of a suitable gas giant's atmosphere, i can't see why not

[kerbiloid]

If the planet is Zeelich, it doesn't have to be a giant.

You can just go by floating ships, like by the ones at the Otringal haven or at the Island of Francos (btw about ISRU).

A rather perfect, but underestimated world.