This is my second question in the series Saturnian Cloud Cities. The first one is Would this concept for a cloud city on Saturn work?)

So, I am not going into details about the cloud-city here in question, but I am gonna do a quick recap:

The cloud city is essentially a large zeppelin, which consists of heated hydrogen. The source of the heat comes from long kronothermal cables I call them kronothermal and not geothermal because Kronos (Saturn)+thermal=Kronothermal. These kronothermal cables dip down very deep into Saturn's atmosphere (but not even remotely close to the core or even the LH2 oceans) just below the water-ice cloud deck. The electricity is produced by means of massive titanium wind turbines which are durable, and spin under the intense winds of Saturn. For additional details, refer to this question.

However, now let's get back to the point.

Let's say, the airship has a launchpad that extends below the hull of the cloud-city. This launchpad is in question about 2 miles long and half-km wide. This launchpad is meant for launching planes which actually go deep down into the atmosphere to harvest water-ice, and go back to their launchbase. The plane's structure is as follows-

  • The plane resembles a Boeing-747, about 2x bigger. The only difference is that the plane is completely empty and is actually meant for holding water. The only part of the plane that is inhabited is the pilot-room. The rest of the plane is simply a empty place, meant for storing water.

  • The fuselage is made of titanium to withstand high temperatures and pressure.

  • The engine of the plane, is an air-breathing engine. However, this engine actually uses the hydrogen-rich air as an fuel, while oxygen is injected into the engine (In contrast to engines here on earth that inject fuel into the engine). The engine is a ramjet. The oxygen is question is obtained from the algae vessels from the cloud-city

  • The interior of the plane is lined with styrofoam for heat insulation.

  • The entire body of the plane is coated with fumed silica, an hydrophobic substance that prevents icing or damping.

  • The planes harvest water, by actually opening up a giant hole in the fuselage. This hole is filled with many wire-meshes. When the planes fly through the water-cloud deck, the clouds are rammed into the mesh, where they are absorbed, and allowed to drip into the water-hold. The idea is similar to Fog harvesters.

What are the problems with this aircraft design? If any, then what should I do to fix them?

  • 1
    $\begingroup$ I would suggest a fling wing or even better lifting body aircraft instead of a 747. can be constructed more durable, more cargo space, and adds a cool factor. $\endgroup$
    – Gillgamesh
    Commented Sep 22, 2022 at 12:39

3 Answers 3


using reactive propulsion in the case

  • loss of water (oxygen) your typical piston based prop would be fine
  • ramjet, with higher speeds of sound in hydrogen the thing has to move at insane velocities for the stuff to work

That extra combustion heat can be used directly to replicate your main vessel, to have hybrid neutral floating thing, so it to be more a sub than a plane.

And +1 LDutch - you have cables already(assuming they also can be floating, so length is not an issue, as much) so attach water separating station there(also floating one, which does not add strain on cables) and pump water up.

  • pilot

Drop the pilot, there is no land down there, it can be easy be a drone, even on or current tech

  • pressure

Your drone does not have to widstand pressure, except electronics black box comparment.

  • algae oxygen

Do not reinvent a wheel, good old electrolysis will do prefectly here, also considering algae won't have natural ligth, so you shine on them to make typical electrolysis, eh what the point (use carbon for conductive stuff if you concerned by lack of metals, carbon from methane which is enough there)

  • fomed silica

Man, pick a stool is it hot there or is it cold there

If ice forms in cold area so why to dive, collect the ice there (it means concentrations of water are way abundant there, so collect it there)

So yeah, go next iteration


I see an inherent problem with the concept of using an airplane when taking off and landing back from above rather than from below.

Let me explain: on Earth when an airplane has a non critical issue during flight, the pilot can try to glide and attempt an emergency landing. That is, for example, should fuel finish mid flight, there are (slim) chances of coming out of it alive, because gravity helps the pilot reaching home, the only problem being not reaching it too fast.

In your case there is none of this "passive" safety: any issue which will make the plane inoperable or limitedly operable will mean certain fatal failure, because safety is placed in the opposite direction with respect to where gravity pulls, and the plane will plunge deep into Saturn. It's the same reason why no submarine uses negative buoyance for diving, instead it uses neutral buoyance and attitude control.

This considered, I think it would be better suitable to use a variation of the khronothermal cables to retrieve the water, let's call them khronohydro cables.


Flying on Saturn is actually quite realistic: https://what-if.xkcd.com/30/

If your aircraft es specifically designed to fly on Saturn, it should have no problems to do so. After all, even the described Cessna does a good job. I would vote for big retractable nets made of synthetic instead of meshes inside the plane for a bigger area. Depending on the depth you want to go, pressures might be quite high so your aircraft could look more like a submarine and may even use the same mechanisms (buoyancy, just like your city) to go up or down.


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