Hypothetical Airship Design
Musings on airship design, written 6/9/25 at midnight.
I've been thinking about hypothetical first principles solutions for a hypothetical airship that would solve the problems that killed the airship industry in the late 1930s.
The purpose of building airships, is to lift heavy loads. All other flying machines can do everything else. The reason we’re hauling stuff around on these stupid little roads, is because there’s no good alternative. Airships are the answer, you just have to get the design right.
The reason houses aren't fully prefabricated is that there's no way to transport them, we can only use these tiny little roads.
This problem is solved with airships that can carry a 200 metric-ton spec home from the factory to the prepped site.
This decreases housing costs by orders of magnitude, assuming energy abundant robotic housing factories. Housing cost is not a material problem, its a material transport problem. This is the only solution I can see. Any other area of the economy that requires building the thing onsite, can now be moved to a manufacturing plant, and transported to the site at a fraction of the cost.
The main problem is ballast/venting, which can be solved by using a diaphragm-like structure inside the airship..
If the gas cells are separated, and you can increase and decrease the pressure at for each cell individually, then immediately some of the major problems are solved.
Back in the day, to go up and down airships had to dump water, and vent gas, now you just increase the pressure inside the cells to go down, and decrease the pressure to go up. If the ship was carrying cargo, when it dumped the cargo, it had to vent a lot of gas because now it weighed significantly less.
Not sure how this works in the real world, but the core principle is to be able to change the pressure of the cells at will, without losing gas. It makes the ship more efficient, it doesn't have load/logistic limitations, etc.
Materials
Frame: Some sort of low cost Aluminum Alloy 6061-T6 (~5000 kg) provides robust structure (tensile ~310 MPa).
Outer Shell: Aluminum Sheets/Foil 3003-H14 (0.1 mm foil, up to a few mm thick sheets.) ensures low drag (Cd ~0.02–0.025), high strength (~130–150 MPa), and durability.
Gas Bags: Mylar (if needed) (~100–250 kg) offers excellent H/He retention and modularity.
Diaphragm: CFRP rising and lowering platforms (~410 kg) to control buoyancy.
To lift 200 metric tons, the airship requires a volume of, say 200,000 cubic meters. With a 7:1 fineness ratio:
Length: ~270 meters
Width/Height (Diameter): ~40 meters
This would be a big ship, but definitely doable from a first principles perspective. We only need to ask the question, do the laws of physics prevent this an airship of this magnitude from working?