A hydrogen airship you can build in a shop and then never have to land.
Powered by sunlight, fuel cells and engines so that no single technology failure ends the flight. Sized to be lived aboard by two people for a year. Able to land on water and operate as a boat.
This is an open engineering notebook, not a concept renderer. Every number was computed by the model at build time, by the same functions the tests call. Where the model is guessing, it says so, and where a gate fails it is left failing rather than tuned away.
The near half of the hull and cover removed. Cells, keel corridor, gondola and every compartment.
Four things that decide the design
Each is a constraint the vehicle has to be built around, and each is counterintuitive enough that a design drawn without it looks fine and is not.
There is no trade against being heavy
An aeroplane that comes out overweight loses range and still flies. An airship has no such trade: the buoyancy is fixed by the envelope, so a kilogram over is a kilogram that does not leave the ground. At 90 m this arrangement is 5,495 kg heavy and there is nothing to give up. The hull is 118 m because that is the length at which the masses fit.
A sealed pneumatic float is stiffer than the water
Its stiffness goes with ABSOLUTE pressure and not gauge, so it is nearly sixty times stiffer than the waterplane it replaces. It limits force only if it VENTS. A rigid hull is held to sea state 1; a vented bag reaches 6; a sealed one reaches none at all.
The ocean is the ballast
17.1 kelvin of diurnal swing, 10.0 K of superheat under heavy cloud and 7.0 K of supercooling under a clear night sky, moves lift by 2,112 kg against a 550 kg landing trim. The vehicle takes itself off by mid-afternoon and presses that onto its gear before dawn, and no passive device can be sized for a load that swings by 3.8 times the trim, twice a day.
A vehicle afloat is sitting on unlimited ballast, and moving water costs about a three-thousandth of what compressing lifting gas does. A 2.1 m³ bladder and a 115 W pump track the swing, which is the cheapest fix in the design and closed the last gate that was failing.
The building costs more than the airship
$3.3M of materials has to be assembled inside a 133 m shed that costs 7.4 times as much, cannot be rented, and is required because a rigid airship cannot be assembled in weather. Two people can hold the finished ship broadside in 0.90 m/s. This is the page where the answer is no, and the reason is not the airship.
The case, in order
Read top to bottom it is the argument for the design. Jumped into anywhere it is a reference.
- 01The shipWhat is it, where is everything, and could you live in it?The arrangement and the interior: a cutaway, an inboard profile, four sections and a plan of every room with what is in it. All drawn from the same stations, footprints and masses the budget integrated.
- 02Why this and not something elseRigid, semi-rigid, non-rigid, hybrid-lift or variable-buoyancy?All five on one basis, each calibrated on a vehicle that flew. Three are lighter than the one chosen, and each is lighter for a reason that costs something a liveaboard cannot pay.
- 03Does the loop close?Can sunlight alone keep it up for a year?Solar collection integrated over the real hull surface, a fuel cell and electrolyzer round trip, and a day-by-day mission integration that reports the day it fails rather than an average that hides it.
- 04Will it hold together?Does the square-cube law let a carbon frame carry this?The mass fraction against every rigid airship with published figures, the buckling allowables that actually size the frame, and the gust case that turns out to govern rather than the static one.
- 05Land it on waterCan it float, and can it get anywhere afterwards?Flotation is trivial and it is not the problem. A simulator that integrates the real seakeeping, and the finding that a sealed pneumatic float is stiffer than the water it replaces.
- 06Fly itWhat does it feel like to handle?The project’s own 6-DOF solver at 100 Hz, with the full added-mass tensor. Slow to respond, slow to stop, and overdamped at cruise where it wallows at rest.
- 07What breaks, and does it kill you?Eight ways this vehicle fails, and what happens next in each of them.An FMEA whose consequences are computed from the mass statement rather than asserted. Seven of eight are survivable. The eighth is a wiring diagram, not a physics problem, and it is the one worth fixing.
- 08Could you actually build it?What does it cost, how long does it take, and where would you do it?A bill of materials priced at what an individual is actually charged, a labour estimate cross-checked two ways, and the building. This is the page where the answer is no, and the reason is not the airship.
- 09Does it hold up?Does the model reproduce ships that actually flew?Every rigid airship with published figures, modelled from its own envelope and compared. Where the model misses, the discrepancy is recorded rather than tuned away.
- 10Where the model is guessingWhat would change the answer if it were measured?The uncertainty register, sorted by how much each unknown moves the endurance number. This is the research queue: what would have to be measured before any of the rest is worth trusting.
The rules everything follows from
There is one model. The site reads it, the simulator integrates it, the documentation renders from it. If a number appears in prose and also in the solver, that is a bug.
The corollary that governs day to day work is that the figure of merit is days aloft. Not speed, not range, not payload. When two designs conflict the one that stays up longer wins, and it is why hybrid lift loses here and wins nearly everywhere else.
Never invent a number. A lint rule fails any numeric literal in the physics packages that lacks a source or a derivation. Values that are genuinely unknown are encoded as uncertain, with a reason and with what would resolve them, and they appear in the research queue sorted by how much each one moves the endurance figure.
The baseline is stationed at 15° latitude and 2,000 m, holding station against 8 m/s for 65% of the day and drifting the rest.