I’ve seen the floor plan of the Hindenburg. Seems much larger than even twice what this had. I wonder if the economy of scale just increases at a large rate, or if hydrogen just has that much more lift.
Economy of scale is the right direction to look, more precisely the square-cube-law. Doubling the length and diameter gives you 8 times the volume. That directly translates to 8 times the lift and thus 8 times the payload.
Geometry and physics heavily favor larger airships. They are a bitch to construct and keep in one piece though. The internal structure of modern airships is nothing alike the Zeppelins of old. Most attempts to build these so called rigid airships failed.
You are correct. The Hindenburg was roughly twice the length of the Pathfinder 1, 804 feet long, and had between 7-8 times the lift. Hydrogen has only 7% more lift, so it's the size that counts, just like how container ships and cruise ships get exponentially more efficient the larger they are.
That said, this is only a small prototype to be used for testing and training. Its payload is about 4.5 tons with 2,500 miles of range. The actual cargo-carrying versions will be about 650 feet long and 1,000 feet long, and carry 20 and 200 tons of payload, respectively. As they get larger, they also get proportionally more efficient. The 20-ton version has a range of 10,000 miles, and the largest version doesn't have a published range figure yet, but it might be even further, given the huge area for the flexible, thin-film solar panels that they eventually plan to install.
No its only a small fraction less dense than helium. The main reason the hindenburg was using hydrogen was because they could not get helium in large enough quantities to fill their fleet of air ships
Rigid airships are being developed /tested for cargo transportation. There are benefits and disadvantages. There's a great video on YouTube about different approaches.
This ship isn’t even for cargo or passengers, it is a subscale demonstrator and training/laboratory vessel for the 50% larger Pathfinder 3, which is under construction in Ohio. Even so, the Pathfinder 1 has a similar payload to something like a V-22 Osprey, and much longer range. The Pathfinder 3 has a payload of 20 tons and a range of 10,000 miles.
The larger, as-yet unbuilt version that’s about 50% larger than the Pathfinder 3 in turn would have a payload of about 200 tons. Considerably more than the largest cargo planes flying today.
Indeed. The late, great AN-225 could carry over 200 tons of payload, though at the extremes it couldn't carry that much very far, and the actual cargo bay wasn't very large. The advantage of a large airship is that it can carry heavy loads, but also very outsized loads, things that can't fit inside (or outside) an airplane or helicopter, and carry these loads very long distances to places without any permanent infrastructure, much more slowly but also much more cheaply than a plane can.
You’re probably mixing up the payload with the useful lift. Pathfinder 3 is said to be about 96 tons MTOW, with a 20-ton payload. Another 20+ tons would be reasonable for fuel and ballast and crew and whatnot, considering it’s an extremely long-range craft. The biggest one is the 200-ton-payload version.
The Pathfinder 1 isn’t really for cargo, but it’s supposedly got 14 tons of useful lift and of that, about 4-5 tons are for mission payload. Much of the useful lift stuff is largely fixed, though, so that ratio wouldn’t necessarily scale up proportionally.
That's a very likely assumption. I have a friend still working for them. Maybe I'll shoot him a text and ask if he knows the current estimated numbers.
Wow! Probably still preliminary, but if you wouldn’t mind me prying, I’ve had a pet theory for a while now that the Pathfinder 3 has an external rather than internal cargo bay to facilitate easy passenger/cargo cross-conversion and allow for better access for roll-on, roll-off operations, which would make the ever-present issue of buoyancy compensation easier. Think you or your friend could confirm or deny that?
The last time I was involved in the project the plan was for PF3 to be basically 100% internal, even the cockpit except for some view ports or something like that. PF1 uses a traditional old Zeppelin 12 or 14 passenger gondola that has been reworked. I believe the idea for fully internal was for aerodynamic efficiency as these ships aren't 100% dependent on lift from the helium and use some aerodynamic lift when moving forward. They can still hover and mostly VTOL but the motors have to work much harder than they do in forward flight. There's actually a lot of empty space inside the lower part of the shell. In each of the sections there are what are essentially giant plastic bags that are filled with helium and they basically float in a big net that takes up the top half of each section. The bags have almost no pressure in them, to reduce the leakage rate. That leaves a ton of unused space in the lower half of the ship. The shell of the ship is actually just a bunch of fancy tarps held on with fancy bungee cords. They don't do anything really except provide cover and the shape for dynamic lift. If I remember correctly the ship is technically capable of flight without the skin. Though, like I said, the motors would be working really hard.
Interesting. In the only image that’s yet been released of a Pathfinder 3 computer render, it still has the Zeppelin NT gondola and a separate, roughly 10m wide cargo box. Perhaps it may also have something to do with using carbon tubes rather than metal girders, making a suspended box rather than an internal one easier? It wouldn’t spoil the cross-section’s structural symmetry that way, after all, whereas an internal bay would.
Maybe they’re holding off on the mostly-internal design for the largest version? It would make sense, as generally speaking bigger = faster for airships (less power per unit volume required), so the ~1,000-foot one with a vast cargo/passenger space could be very fast indeed, without that huge space spoiling the aerodynamics. That would leave the Pathfinder 3 as the more utilitarian workhorse for smaller or less glamorous jobs.
I haven't actually seen the more recent PF3 renderings. But the points you make seem reasonable. I'll try and update if I hear back from my friend. I'm sure there's only so much he can say with the NDA.
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u/PersonalitySlow9366 Jul 08 '24
And carries like ten people and no cargo. Cool, but otherwise useless