1. they get "free lift" but you need a lot of gas to lift a lot of mass, which quickly makes them extremely unwieldy as it leads to gigantic cross sections (and sheer stuff to move, positioning a lift bag the size of a sports stadium is not exactly great, and requires humongous engines)
2. they're so damn slow
3. even ignoring the tendency to get on fire, hydrogen is a pain in the ass, it absolutely refuses staying put and embrittles structural metals leading to accelerated fatigue
> We fly in aluminum balloons filled with jet fuel all the time.
Hydrogen ignites significantly more readily than jet fuel does, and protecting the gigantic volume of an airship's envelope (which is multiple times that of the payload) is a lot harder than protecting a plane's fuel tanks.
Not to mention the airship still need fuel tanks to move around, it's not a captive balloon.
Take a look again at the video I linked to and try and explain how jet fuel doesn't really catch fire and isn't much of a problem if it does.
Preventing an onboard fire is probably the #1 concern of jet designers.
Experience has gotten them pretty good at it. Damned good. Amazingly good. But never forget that jet fuel is not safe. It burns. It burns hot. It'll melt everything on an airplane it touches. It'll burn your wing off in seconds. The whole point of jet fuel is it stores a LOT of energy in a very small amount of weight.
Airlines have gotten amazing good at evacuations, such that I am surprised how well the general public is at them in emergencies.
Look at pictures of any crash where everyone (or almost everyone) survived and the fire damage to the plane is frankly astonishing.
Hydrogen zeppelins could be designed to nearly perfectly mitigate all fire risk; the real danger is weather related. (Ideas such as hydrogen can’t burn if oxygen isn’t present, fireproof bags, gondola suspended below so fire can’t reach it, emergency evacuation planning for when it does hit the ground, capability of venting, fire suppressions, etc).
Airplanes are safe in part because we've already made all the mistakes and learned from them. How many (deadly, expensive) mistakes would it take to get lighter-than-air craft to the same point?
Yeah, they'd likely be best used as "cruise ships in the sky" where they can take advantage of large swaths of empty space (you could have ballrooms in a zeppelin pretty easily as they wouldn't weigh much) and the speed wouldn't be a huge issue.
And you'd likely have to make them out of something other than metal, and it would vent hydrogen most of time.
For passengers sure, they are slow. They could instead transport cargo.
I think the biggest problem with them is mooring. It's a complex process, much more so than landing a plane, and requires lots of ground crew. It would have to be automated first.
For large airships, unless stored indoors (which is of course hard because of the size of the structure required) they are essentially permanently in flight. The Goodyear blimps, for example, are followed as they travel by portable (truck-mounted) mooring towers but must have pilots on board 24/7 even when moored, because a modest wind can easily blow the mooring tower over if pilots don't maneuver the ship "on the ground." In high winds mooring is simply impossible and the airships must remain aloft. The logistics of this operation are very complex, and the airship must be able to swing 360 degrees while moored to allow for maneuvering, which requires a huge area. The result is that the Goodyear blimps rely on a pretty limited set of mostly small municipal airports that they have experience with. Closed air force bases are popular since they're most likely to have a far corner of the tarmac that the trucks can easily drive out to but that has no structures or other aircraft use that the airship would interfere with. The Goodyear website has a picture that gives you a good idea of what this looks like: https://www.goodyearblimp.com/behind-the-scenes/img/emeablim...
Not pictured is the truck of helium cylinders that accompanies the blimp for top-ups, which are required as I understand it mostly due to leakage, as the pilots carefully avoid venting helium due to the high cost (it's an option for emergencies).
> For passengers sure, they are slow. They could instead transport cargo.
(1) applies triple for cargo, cargo which is fine with slow tends to be heavy. For reference, the Hindenburg had under 20 tonnes of useful lift, the ship itself weighted around 200 tonnes dry.
If you're happy with your cargo going under 200km/h, you're probably fine slapping it on a truck or five, or on a train with some point-to-point trucking.
It's hard to fathom how incapable airships are, they really aren't very good as you scale up, the use cases where they have any sort of superiority are extremely limited, leading to a very small market.
They're super ultra cool looking and everything, but their reality is absolutely dreary.
The closest thing to a viable use case for airship cargo is the one Cargolifter was aiming for, getting objects too big for roads to landlocked destinations. And the challenge that comes with that was illustrated quite well by Cargolifter: starting with a small craft and sizing up with experience is impossible because for loads fitting a road ground based transport will always win. (I'm sure that CL160 would have changed the economics of wind power forever, but they were too early for that use case to materialize)
Yeah, for cargo they're absolutely insane - maybe in some rare cases they could replace cargo/heavy lift helicopters - but otherwise they don't have much in the way of advantages.
Possibly better: don’t use gas, but enclose an aerogel such as aerographene (https://en.wikipedia.org/wiki/Aerographene) in a strong enough, airtight shell and pump out most of the air.
One of the engineering challenges will be to make this strong enough to withstand the air pressure without getting too heavy. That may require finding new aerogels. You probably also want an aerogel that doesn’t burn easily.
More airships crashed due to poor weather than fires, including the Akron (which was the deadliest of the airship crashes.) Or consider the USS Shenandoah, a helium airship that was torn apart by the weather. It didn't burn though, and most of the crew survived (29 of 43).
Perhaps with modern weather forecasting this threat could be effectively mitigated, but I have doubts.
Planes have numerous advantages, particularly in the early days when mass adoption was still in question: Foremost, they're smaller. This means when one crashes, fewer people die (remember, I'm talking about the early days; Tenerife doesn't count.) Because they're smaller, they cost less. That means fewer investors get hosed when there's an accident, and it's relatively easy for innovators to find funding for new airplanes despite the crashes. Because airplanes were so much smaller and cheaper, it was even practical for a one or two man team to fund and construct their own in their garage; an airship is a much more demanding undertaking. Because they're smaller, they're easier to store inside during bad weather. They're also faster, which makes it easier to evade bad weather and also means you don't have to anticipate bad weather so far in advance. They can land almost anywhere, even in some farmers field, but airships can only be moored in a prearranged locations. That gives an airplane many more options for dealing with emergencies, which contributes to a perception of relative safety.
It can likely be done quite safely, as the gasbag of the Hindenburg was very flammable and could have burned even if full of helium.
And hydrogen is basically free.