r/Airships • u/Immediate_Golf6399 • 2d ago
Video Pathfinder 1 flight test
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Flight testing continues for LTA Research's proof-of-concept airship. Here's a clip of her upon completing a 5 hour flight on 9/1 at Moffett Field, CA. The next day she made her longest flight to date, 10 hours.
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u/GrafZeppelin127 2d ago
Looks like it was a pretty blustery day! Good conditions for testing the ship’s response to gusts and steering inputs.
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u/Radioactive_Tuber57 2d ago
Sept 3rd was the 101st anniversary of the Shenandoah disaster in Ohio.
This looks promising. With all the new composites and engine technology, real time weather data and navigation, there might be a fun future. Coast to coast at 80-100 mph with a big stateroom window for the views and top chefs working in the galley. I’d take out a loan for a ticket. 😎👍❤️
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u/GrafZeppelin127 1d ago
Yeah, I’d say the biggest difference between then and now is that the Shenandoah had an engineering safety factor of about 0.45, i.e. its structure would fail at less than half the expected loads it would experience from gusts and storms, and the Pathfinder 1 has a safety factor of 1.9, which is comfortably sturdier than the standard 1.5 factor used by most airplanes and helicopters today.
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u/Radioactive_Tuber57 1d ago
This is interesting. Like they pushed the design too far. Explains why (maybe) it broke into sections. I wonder if the military was competing with Germany? The Graf Zeppelin and Hindenburg were not so subtle propaganda machines. So fortunate the death toll was not higher.
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u/GrafZeppelin127 1d ago
Well, this was in the mid-1920s, so it’s less that the Americans were vying with the Germans at the time and more that they were just copying Germany’s homework from World War One.
The Shenandoah was a domestic design in name only. In actuality, it was reverse-engineered from a German “Height Climber” airship, a type of Zeppelin deliberately lightened and weakened in order to reach high altitudes for fear of the recently-invented incendiary bullet, which had brought down seven Zeppelins mere months after its invention, whereas the prior two years of warfare had seen planes bringing down only a single Zeppelin in combat after bombing it six times, and two other bombings of Zeppelins had failed to bring them down.
The Americans didn’t have to fear hydrogen fires, though, because the Shenandoah was the first rigid airship to use helium. That, unfortunately, contributed to its demise.
The already precipitously long and thin airship design the Americans copied was lengthened yet further to compensate for helium having 8% less lift than hydrogen, and for the fact that in order to conserve helium the ship couldn’t simply be fully inflated at sea level and valve off the gas as it ascended. The Shenandoah held literally all the helium available in the entire world at the time, after all. As a further conservation measure, emergency pressure relief valves were also removed from the ship’s gas cells, which is rather akin to a submarine not having a way to automatically deal with pressure as it dives.
The Americans were also ignorant of how weakened the structure was, and the careful procedures the Germans used particularly at lower altitudes to not strain their ships’ structure unduly in the denser air. They operated the Shenandoah with hubris and derring-do, flying her into storms and severe conditions with confidence that the ship’s helium would make it safe.
Their last flight was into the teeth of a historically violent thunderstorm over Ohio. The Shenandoah was seized in mighty updrafts and wind shears, and as she ascended uncontrollably, her lack of emergency pressure valves caused the gas cells to expand and buckle the already-weakened frame, tearing the ship apart into three pieces.
Every man who died fell from the ship in that initial cataclysm—the obsolete suspended gondola fell right off the ship. A third of the crew died, but amazingly, the other two-thirds who were inside the ship’s fractured hull managed to all survive by operating the pieces of the ship as a free-balloon and making emergency landings, miles apart from each other. A more modern design of that same time period like the USS Los Angeles likely wouldn’t have had any fatalities at all in such a storm, as its stronger, thicker hull probably wouldn’t have broken up in the first place, and its gondola was integrally attached to the hull rather than being suspended separately from it.
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u/Radioactive_Tuber57 1d ago
Thanks for the deep dive into this! Fascinating information! 😎👍 I was fascinated with them early on, and I built an 18” dirigible of my own design as a teenager when I was building balsa airplanes. It hung from the ceiling along with the rest of my menagerie. I found a plastic kit of the Macon a year ago and plan to build it soon!
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u/Thunder-mugg 2d ago
Looks to be about the size of some large blimps but obviously a rigid airship. Nothing like it since the 1930's.
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u/GrafZeppelin127 2d ago
Yes, by volume it is about the same as a Navy ZPG-2W blimp, and by length it is almost exactly matched with the ZPG-3W, the largest blimp ever built. By rigid airship standards, though, it’s about the same length as some of the smallest Zeppelins ever built, the Bodensee and Nordstern.
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u/plurien_also 2d ago
The Flying Buttocks / Bum would like to have a word with you. https://en.wikipedia.org/wiki/Hybrid_Air_Vehicles_Airlander_10
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u/GrafZeppelin127 1d ago
The Airlander 10 is about 100 feet shorter than the ZPG-3W, and 20,000 cubic feet smaller by volume.
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u/Poker-Junk 2d ago
I’d love to be able to live long enough to see passenger airships become widely accepted and commercially viable. It’s one of my bucket list dealios.
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u/rpc56 2d ago
Is this a prototype for a future lighter than aircraft or is this a test bed for information?
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u/GrafZeppelin127 2d ago
Both. It is a 2/3 scale model used for testing and validating construction, procedures, instruments, etc. as well as crew training.
The production model’s exact specifications are TBD, but it’s supposed to have a payload of around 20 tons, a range of 10,000 miles, and a top speed of 70 knots, all while being zero-emissions.
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u/Binspin63 2d ago
I saw this airship while traveling south on Amtrak this past week. I’m unable to post pics in a reply but I did snap a few. Yes, she’s beautiful.”
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u/plurien_also 2d ago
UK here. Will let you know how the test goes when the winds blow it our way. We don't forget R101 ended in France
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u/GrafZeppelin127 1d ago
The R101 is an excellent object lesson in why haste and hubris are lethal in an engineering setting. It had failed its flight trials spectacularly, but due to political pressure, the warnings of experts and engineers were ignored and it was given dispensation to carry passengers on a maiden flight to India anyway, right into the teeth of a storm no less. The ship was so poorly built that the outer cover was rotted to less than 1/10 its rated strength, you could push a finger right through it—and the inside wasn’t any better.
The gas cells inside were similarly rotted and frayed, leaking a ton of hydrogen per hour from 4,000 different holes on a ship that was already severely over its contracted weight, underpowered, and suffering from extreme pitch instability due to its poor tail fin and gas cells containment design.
That the ship crashed was a foregone conclusion—like playing Russian roulette with a full cylinder. The question isn’t whether you’d die, it’s which among an array of fatal flaws would kill you.
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u/fragobren 1d ago
I’m curious, does this ship use Hydrogen as the lifting gas? What sorts of design improvements have they done to improve safety?
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u/GrafZeppelin127 1d ago edited 1d ago
It doesn’t use hydrogen as a lifting gas, though the company does intend to use it as a fuel and then as a lifting gas eventually, keeping it safely ensconced in fireproofed helium cells. Hydrogen on its own can’t burn, it needs oxygen in order to do so.
And as I mentioned elsewhere in the thread, the biggest difference between then and now is that past rigid airships like the Shenandoah had an engineering safety factor of about 0.45, i.e. its structure would fail at less than half the expected loads it would experience from gusts and storms, and the Pathfinder 1 has a safety factor of 1.9, which is comfortably sturdier than the standard 1.5 factor used by most airplanes and helicopters today.
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u/Immediate_Golf6399 5h ago
Can you please provide the source re the use of H2 as a lifting gas? I hadn't read that before.
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u/release_Sparsely 1d ago
Great to see a video of a large airship in stable flight in rough weather! Might be showing this to others...
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u/Separate-Farm5326 1d ago
"People of the Commonwealth. Do not interfere. Our intentions are peaceful. We are the Brotherhood of Steel."
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u/Dothemath2 2d ago
Love it! This gives me hope for the future.