# Which physical laws or attributes would have to be changed to increase the buoyancy of an airship?

As I came to realize from a previous question of mine, my vacuum airships are apparently not as good as I hoped they would.

I still do want to use them more or less how I envisioned them, and I'm curious which laws of physics would need to change to make vacuum airships (or airships in general) more viable.

The first solution I thought of was changing the gravity, but that would have other implications and I now believe that it wouldn't even change anything, as higher gravity = more buoyancy, but also more weight that needs to be carried, and the same issue the other way around. Correct me if I'm wrong.

The second fairly obvious solution would be making the air denser, thus increasing the buoyancy. This is the topic of another question.

However, I'm curious whether there is another way to make airships more viable / more buoyant that I haven't thought of. Anything goes, although I don't want to mess with basic laws like conservation of energy etc.

• I say this in jest, of course, but what they need is negative mass (en.wikipedia.org/wiki/Negative_mass). Plus it gives them instantaneous FTL travel through wormholes as a nice bonus. Commented Jan 22, 2021 at 12:54
• Are you looking for bouyancy specifically or for anything to make an airship fly? Hybrid airships use winged surfaces to add lift capacity, which allows airships to be heavier than air and still fly. Changing the angle of the wings controls their total lift giving you control over what height they'll fly at. Commented Jan 22, 2021 at 13:52
• @Demigan the main uplift should come from something balloon-like. Planes and the like are not what I'm looking for, although wings, (rigid?) sails, etc. are an option. Commented Jan 22, 2021 at 14:10
• Not an answer, but would floating (room temperature) superconductors above magnets/magnetic forces (of Earth) solve anything, at the very least as an additive to your airship buoyancy? This instead of making the air denser? Some technobabble might be required though. Also, Demigan's question revolves about hybrid airships. Most of the lift comes from the balloon, while the final x percent comes from the wings at speed. It's basically an airship. Commented Jan 22, 2021 at 14:58
• @PixelMaster I think Trioxidane meant that a difference in how magnetism on a planetary scale works (or alternatively how superconductors work on the planet's magnetic field) could give you the change in physics you need to make airships more bouyant. Commented Jan 22, 2021 at 15:43

Make hydrogen not explosive

The problems with airships is not purely the buoyancy but to have enough buoyancy without a hazardous gas while resisting the air pressure. Hydrogen has enough buoyancy but is explosive, Helium does not have enough buoyancy for large airships. Vacuum has a problem that you need a hard outer shell to withstand the air pressure.

I don't know if this falls in the category of messing with basic laws, since you seemed willing to alter gravity but you could make hydrogen not explosive. This would allow the same airships as the Hindenburg and such. You could also define a new gas with roughly the same properties as hydrogen that is not explosive, resulting in the same result.

Vacuum low density load bearing foam

Another option might be using a ultra light synthetic foam such as Aerographite with a density of 0.18 mg/cm^3. Create a balloon from, seal the outside and vacuum out all the remaining air from the void space. The only problem is that you need to make it load bearing. So for the solution propose the new material HeavyAerographite that has a load bearing capacity to withstand the compression of the outside air pressure. In principle this might be doable without breaking any physics laws.

• As evident from my linked question, creating a vacuum-filled sphere is not a problem; my world effectively has a material just like what you suggested in the second paragraph. My problem is that I want to create more buoyancy than a vacuum-filled sphere would have following the laws of the real world. Commented Jan 22, 2021 at 13:40
• Are you sure that a modern airship would not be able to use helium? For example the Hindenburg could lift around 9 and a half tons at 230m length. The Airlander prototype could lift 10 tons at 1/3rd the length. The caveat is that the Hindenburg was designed more as a luxury passenger ship than cargo hauler so some weight is in the passenger compartments, but modern materials, new designs that use wings for lift and heavier-than-air airship possibilities could offer the possibility of helium airships. Modern design also limits the flammability (not explosiveness) of hydrogen. Commented Jan 22, 2021 at 13:47
• making hydrogen not explosive would have huge impacts on biology.
– John
Commented Jan 22, 2021 at 14:11
• Hydrogen is not explosive in itself, you need oxygen. The best (and physically sound!) option is to have a non-oxygenated atmosphere. There is a slight problem that H₂ is still reactive with a lot of elements, so you do not have that much choice here (and still support life as we know it). Commented Jan 22, 2021 at 15:18
• @Demigan Apparently helium (twice as heavy) does not have enough buoyancy for airships like the Hindenburg. For blimps they use helium but they have much less carrying capacity. Commented Jan 22, 2021 at 15:40

Have a material that can withstand extraordinary heat, and a way to vent heated air - safely

If you heat the gas inside your airship, the gas would decrease in density. You need to stop the airship from expanding (and thus exploding), so you need to control also the amount of gas in your airship too. If your hydrogen/helium was heated inside the airship (without exploding), and vented out as required, your airship would have more lift. The mechanisms required to do this need to weigh less than the benefit of heating the gas though.

LZ126 used 23000kg of gasoline on a typical cross-atlantic voyage. Imagine if all this weight was saved by having a new fuel source that was much lighter! Maybe in your world gasoline has a quarter of our worlds weight. Also, having gondolas that were made of a lighter material will help too, having structure much stronger and lighter than aluminium trusses, or the skin itself could also be much lighter.

You could also consider other factors to make Airships more desirable. These include:

Make the world completely windless

Wind is a major impediment to Airships, being unpredictable, influencing your course, and also capable of destroying them easily. If wind did not exist in our world airships would be much more controllable and safer, both cruising and docking.

Make a flexible material that can expand and contract the volume of the airship

Your lifting gas is actually dependant on volume. If the skin of your airship is variable easily, you could control the pressure inside and thus the boyancy. Having such a fine level of control would enable Airships to change the altitude without the use of 'forcing' it down using engines. Controlling volume would also reduce the need for ballast - a major 'dead weight' that works against your boyancy.

Docking would be much easier too - which of course was a dangerous exercise and another major source of airship deaths.

Make airplanes difficult to fly

A major impediment to Airship development was simply that airplanes became cheaper, safer, faster and more reliable. By removing fixed wing aircraft from history we would likely still be using Airships today. Perhaps a fuel is lacking in your world meaning airplane engines did not have enough thrust to create lift, or there were no materials rigid enough / light enough to have a rigid wing, or simply they hadn't been invented yet.

• During the later stages of the cold war the US used various early warning systems over the North Pole. At some point the weather became so hazardous with windspeeds and cold that everything was grounded. Everything but airships that is. That puts quite a dent in your idea that airships are easily destroyed by wind. Commented Jan 22, 2021 at 15:48
• @Demigan That's assuming that the airships are tethered and stationary - not useful for any kind of voyage or transport. It has long been established that cruising airships are much more susceptible to influence by winds than fixed wing aircraft.
– flox
Commented Jan 22, 2021 at 15:59
• where did you get that idea? I've only read about airships patrolling hundreds to literal thousands of miles, none were ever doing their missions while tethered. Commented Jan 22, 2021 at 20:45