Here's an interesting article about the economics, it sounds like Helium won't be economical at scale, because we have so little of it. Hydrogen could work though.
The Hindenburg disaster actually shows how safe hydrogen is. Despite the enormous fire, the majority of persons on board survived, and this with 1930s' state of burn treatment. Unlike kerosene flames, hydrogen flames radiate little heat. Hydrogen does not stick to surfaces or people.
IIRC, Hindenburg was supposed to have a thin outer helium layer surrounding the hydrogen providing the bulk lift, as a safety measure to inertize it, in case of leaks. But due to a wartime shortage of helium, the outer layer was filled with hydrogen as well, compromising safety. The original design was sound, but corner cutting caused the disaster.
The thing is that hydrogen's buoyancy is so high that it lifts up above the dirigible very quickly once released. So fire risk isn't really that great in terms of burns.
The bigger problem is the "lack of buoyancy" of the rest of the dirigible (and the impact with the Earth affecting the passengers). So that's a bigger issue to address, engineering-wise.
It is interesting how the Hindenburg is remembered meanwhile all the hundreds of planes that crashed in the Alps are forgotten. And this was when only VIPs could afford to fly.
It seems until the 1970s flying was like Russian roulette.
I've see quite a few images of heavier than air aircraft in lots of tiny pieces. One of my old colleagues starred in a popular TV series dedicated to air crash investigations, and he was working for a trade publication promoting flight...
It's just a meme at this point, and has been for 60 years. Fixed-wing airliners become a gargantuous fireball of death if they ever happen to hit the ground after takeoff, which they have occasionally done with someone filming the disaster.
You can of course debate the relative safety, but for eye-catching disastrous video material the world of aviation has a thousand times more than airships.
I think it's shortsighted to think of it as an alternative to conventional aviation. People send freight (and themselves) by plane because it's fast; in the case of cargo it's goods that are so expensive that the speed is worth it.
If you're not in a hurry you can use ships, which are quite cheap.
The value, IMHO, is in landlocked areas without rail links like Africa and central Asia. These are areas that mostly skipped the landline and went straight to wireless. Airships would be an analogous transition for them possibly even for passengers, though I think of freight.
If we average that out to 4 days to make a round trip, whereas today's airliners can make the round trip in a day, the capital cost of a seat on an airship has to be multiplied by 4 compared to the capital cost of an airliner because the seat on the airliner can move 4x as many people.
On top of that, the airship is going to need to provide a much higher level of amenity (space, food, water, supplies, staff) to be comfortable for a much longer trip.
Ocean liners became uneconomical early in the jet age for this exact reason: you're not just burning up your own time riding a slow boat, but you have to pay for a much longer time on that boat.
In the 1960s, Boeing thought the 747 was a stop-gap solution because it was commonly thought supersonic airliners would be able to manage at least twice as many flights per unit time as subsonic airliners. When the Concorde came along it became clear that you couldn't manage this trick because you'd have to take off and land late at night, something the community finds unacceptable.
The odd thing about supersonics is that the fuel economy gets better as you go faster (in the range from Mach 1 to the low 3's) and if you were able to make an airliner that flew at SR-71 speeds you might be able to manage a double flight rate.
All true but the economics are different when there is little cap ex budget. You don’t have to build an airstrip or lay rail to ship bulk goods like grain this way, and it need only go from inland to a port.
Think Almaty to Singapore or Lusaka to Luanda. Any passengers for such a journey can put up with a lot of privation for a low cost trip (but I imagine passenger traffic would be fit into a cargo trip on a space available basis; I can’t imagine passengers being primary)
You could use containers for some goods; bulk goods like grain could be decanted straight into the hold of a bulk carrier
Fuel cost (which heavier than air aircraft really ought to be able to reduce) is double the amortised capital cost in an airline's budget, and there are plausible reasons to believe the capital cost of airships will be smaller (greater size, but less stress placed on parts). So everything else really isn't equal.
For related reasons turboprop aircraft are more economical for short haul flight than jets which could notionally fly more sectors, and Concorde flew very little during the daytime either because the fuel cost of getting to supersonic relegated it to niche use to transport rich people.
I think passenger dislike of longer trips is a bigger obstacle to widespread adoption, but a significant proportion of [potential] flight doesn't involve passengers
> which heavier than air aircraft really ought to be able to reduce
It's not clear. Dirigibles travel at very low altitude, where the air is dense and they have a very high cross-section area. Very high as in absurdly high (A Goodyear-Zeppelin blimp has a diameter of 14m and a gross weight of 10 tons. So the cross-section area is about 600 m2 )
Jet airplanes travel at 10 km high, where it's almost vacuum. They are also very slender. They have a very high lift-to-drag ratio. A modern B-787 (Dreamliner) has an L/D ratio of 20, most other aircraft capable of crossing the Atlantic have an L/D ratio above 15.
On the other hand, dirigibles don't need to worry about lift to drag ratio at all on account of not needing to generate enough thrust to produce lift.
Which is why the litres of fuel per passenger km for the Hindenburg, with 1920s diesel engines mounted on platforms where fuel economy was barely a consideration compares favourably with the same economy metric for modern transatlantic flight after half a century of innovation in jet fuel economy (and cramming passengers into smaller spaces). Needless to say lighter than air platforms without comparable worries about the impact of weight on fuel consumption and with large surface areas are also theoretically superior platforms for electric engines and [partial] use of solar power than heavier than air platforms.
Obviously they're not a pure emissions silver bullet, and plenty of other practical problems would need to be overcome for airships to fill more than tiny niches, but the evidence favours my statement.
The Hindenburg had a total mass of about 240 tons. In its last voyage it burned 42 tons of fuel over 77 hours. It was an unusually long voyage due to high winds, but presumably the engineers who built it took these type of conditions into account, so the takeoff fuel was probably 50 tons or so.
A modern airplane of the same size (mass) is A-330. It has a (fully loaded takoff) mass of 240 tons, and a takeoff fuel mass of about 110 tons, so more than double the Hindenburg's.
Hindenburg's speed was about 125 km/h, while A-330's speed is about 1000 km/h, so about 8 times faster. Indeed, a Frankfurt-New York flight takes about 8-9 hours in an Airbus, it used to take about 60 to 70 hours in a Hindenburg.
Of course, if it takes you 2 days to cross the Atlantic, you need a bed. So, Hindenburg was able to accommodate only about 70 passengers, while an A-330 can easily fly 250.
Finally, regarding solar power. Hindenburg's area as seen from above was about 10000 m2. Current solar panels can produce up to 220 w/m2, so if we cover a Hindenburg with such panels we'd get 2.2 MW peak power, or about 3000 horse-power. Hindenburg's engines were producing about 3300 HP in cruise mode. Today, with better propellers and CFD modeling, you may not need more than 3000 HP to get the same thrust, so at peak solar radiance (noon), you would not need to burn any gas at all. Of course, during the night, the solar panels' output will be zero, but the modern engines may be more efficient, so all in all it's likely that instead of 50 tons you may only need 25 tons.
Air drag increases with speed too. Air pressure at Mount Everest is, IIRC, 30% of sea level value, for a roughly 70% reduction in drag i guess, but if you're moving 5-10x faster, that's a 25-100x penalty.
Airline jets fly at transonic speeds which complicates the calculation a bit but i think not in the favour of the aeroplane.
A little remembered thing about Concorde is that it was wildly popular for charter flights from UK to various warm island countries during the winter - to the point that Concorde revenues would be majority in some winter quarters.
> When the Concorde came along it became clear that you couldn't manage this trick because you'd have to take off and land late at night
What are you referring to here? Is it the noise restrictions? The Concorde was restricted from flying over land because of sonic booms, but that just means you slow down to subsonic speeds just before hitting land on transoceanic flights.
It was noisy as hell taking off because the engines and wing were not optimized for low speed flight.
Airports like JFK and Heathrow all close down in sleeping hours because even conventional aircraft (especially the 737) would wake people up at 2 am.
It is a tough problem balancing good supersonic performance with being able to take off and land. This is why people have considered radical solutions such as an airplane that turns 90 degrees when it goes transsonic. One reason why the SR-71 was successful was that it took off with just barely enough fuel to reach a refueling tanker, a trick you can’t manage with a civil airliner.
You dont need to carry fuel though. Solar on top of the airship can keep it moving along indefinitely, paired the ability to hang around aloft while waiting for more sun.
Photovoltaics are way less powerful than you give them credit for, unless you want the electric motors to only push it at 10 knots... Where pv excels is cumulative kWh per month collection from something like a big cheap ground based array, the amount of watt hours you could collect in 12 hours from a top half of an airship covered in PV is not a lot, compared to the load of powerful electric motors.
I did the math for USS Akron, which was around 240x40m and was propelled by a 3.3MW power plant.
It has a projected surface area of 7500m2, which, using modern, 22% efficient monocrystalline panels, yields 1.65MW, or half the desired amount, which I assume was used mostly for liftoff.
In any case it's the same order of magnitude, so should be at least somewhat useful.
There's always the question of weight, but much of that is the usual glass and aluminium casing.
The devide your numbers in half because sun will only ever hit half the airship. Then realize that when you neee power the most, in bad weather, the sun wont be there. Then subtract the mass of all those panels from the availible payload.
From @Tade0 writing "projected surface area", they have already accounted for the fraction in sunlight. You can also tell this is what was meant by noting a rectangle of those dimensions is larger than the stated projected area, which you should expect from the pointy bits on the ends.
The weather that destroyed the USS Akron seems rather more important than the power source. I wonder if we can reliably make them go above or around clouds these days? I’ve not noticed clear air turbulence in air travel since I was a kid.
If you have a positive answer on the weather safety, and if the PV is light enough that it could be considered a way of reducing fuel use rather than a Boolean yes/no decision to either fully replace a chemical fuel or not use it at all, it seems worth investigating.
Edit: Just realised, while I’m usually unconvinced by RF beamed power, but with that surface area, and the general form of the inner frame, and it being in the sky so less danger from industrial accidents, this might possibly be a case where it could work.
I don't think it's infeasible that air could displace the lifting gas that was compressed, even in a rigid envelope. You could maybe build flexible bladders on the inside for this purpose. Another way to add weight using the same principle would just be to compress outside air into rigid tanks on the craft, making it heavier.
Dirigibles are rigid airframes, not rigid gas containers. They used gas bags to displace normal air from inside the frame and replace it with lifting gas.
I feel like doing this analysis without accounting for carbon is the mathematical version of climate change denial. Like, to not account for it is to deny it needs to be.
Airships can also be useful over land even in places with dense rail/road networks if the cargo is too large for rail/road. A primary example is factory-built housing: currently, such houses have to be manufactured in pieces small enough to go on a truck and then assembled on-site, increasing cost. But if you can build larger sections (or even the whole house) at the factory and just air-lift it to the site, it could be much more efficient.
Note that when the airship drops a heavy load, it might shoot into the stratosphere unless an action is taken due to suddenly having so much lift.
So either you have to vent potentially expensive lifting gas - or get some replacement load, such as water or even a load of rocks. Not an impossible to solve but some site preparation is needed.
But it's much easier to truck in a few dozen tons of ballast than to truck in, say, a 400 ft rotor blade. Transport is seriously limiting wind power, not just because larger gets better wind but also because larger would actually get less nimby, not more: rpm scales inversely with size, and rpm is what draws our attention to where we don't want it.
That was the idea of CargoLifter (https://en.wikipedia.org/wiki/CargoLifter). The plan was to build an airship that can lift 160 t of oversized payload and beat train or road transport on price and speed.
They ran out of money before they could build anything useful (besides a mighty hangar).
If airship startups stopped trying to make them safe by filling them with precious helium, we could have affordable autonomous bulk cargo transports.
If hydrogen airships "explode" at some small rate < 0.0001%, they can stick to transportation corridors away from population centers for the majority of their route to destination.
It seems easier to replace a trucking fleet with autonomous hydrogen-powered airships than to have 100% safe self-driving semis operating on the road alongside human drivers.
There might be a niche market for autonomous hydrogen airships in some other countries, but it would be decades before the FAA allowed commercial use anywhere in the USA.
Besides the lifting gas, the previous comment mentioned "autonomous". The FAA also prohibits autonomous aircraft outside some very limited designated airspace. Until that ban is lifted, they can't be used for any real commercial service.
Since they don't dive into economic feasibility, I did about 3 minutes worth of googling, and found this paper https://www.temjournal.com/content/93/TEMJournalAugust_1062_... that basically says its 20% cheaper than an airplane, but takes 5 times as long. where it becomes economically feasible is when carrying heavy cargo, which in my mind would be better handle by rail (they did not give numbers comparing it to rail). My guess is this will turn out to not be economically feasible and only makes sense if the environmental impact is your primary concern, or as another commenter mentioned, if you don't have land infrastructure already built out.
Assuming these airships are VTOL and can land on non-runway surfaces (e.g. large open fields) you'd think this would beat airplanes by a lot more than 20% overall as you wouldn't have the additional costs of getting the heavy cargo to the final destination, it could be taken straight where it is needed.
So the optimum load would be the long distance delivery of a large, heavy single item in an undeveloped inland area.
The paper doesn't even seem to compare the costs of lifting gasses.
If the airships are completely autonomous and you don't care about a small percentage of them exploding (<0.0001%, away from population centers), then hydrogen is orders of magnitude cheaper than helium.
A fleet of these could replace truckers before autonomous trucking becomes safe enough to put on the road alongside human drivers.
If they're better than rail, you could convert freight trains to commuter or rip up the lines and reclaim the land.
Yeah, a major issue is that there's a shortage of helium with the supplies being rationed so that enough of it can be conserved for medical and other essential needs. Is there going to be enough to supply these airships at a price that makes it viable?
isn't one of the problems of handling airships on open fields that you need a significant ground infrastructure to moor it, tie it down/protect it in stormy/windy weather? unless the airship only operates from certain very large prepared bases and briefly drops off cargo at places, but doesn't have the capability to remain there for any longer period of time unmanned.
Focusing on heavy lift, thats often, and increasingly a niche which incurs massive costs because of increasing urban density, or location of resources needing to move between two points without either canal, or rail, or constraints like bridges and tunnels. Moving parts of aircraft through villages of france, demands an army of planning and consequence for 10cm clearances. If you can lift the same objects you avoid this pain.
If you're doing mining, wind tower deployment or anything similar you're probably negotiating land access and dealing with unexpected problems all the time. Reliable airship lift could reduce costs significantly in this niche.
I'd guess that they're targeting transoceanic freight. A flight from Shanghai to Los Angeles takes ~12 hours, and a cargo ship takes ~30 days. That's a huge gap that could be filled by an intermediate option.
Boundary Layer Technologies (a Y Combinator portfolio company) is trying to fill that intermediate option with small hydrofoil cargo ships. The basic design can probably work, but it's not clear whether a viable market actually exists.
Installing rail is super expensive and limits you to where the rails is and the capacity of the track. Great if you have it but installing more of it involves many billions of dollars.
I could see a use-case for e.g. Amazon using this at scale to move goods around. They currently do this at great expense by flying planes around.
I wonder what the deal is with the economics. People were doing this routinely a century ago and it worked then. What's holding this back now? I've been reading about zeppelins making a comeback for decades now. And somehow it never happens.
John McPhee wrote a fine book on the effort to commercialize lighter than air heavy transport: The Deltoid Pumpkin Seed.
I was watching a BBC episode on Africa's geography and its lack of navigable rivers or good harbors, and how that has held back economic development. These airships came to mind as a cheap way to access that continent.
> Nice idea, but others have tried that and failed
Thank you for the background; however, "but" is probably not the conjunction you want here, unless you have good reason to believe this can't be done? That wiki page suggests the project was technically sound but ran out of budget. Obviously things tend to fail the first few times you try them, especially when underfunded.
Yeah, the title of the article immediately made me think of that other company that was "poised for an aviation revolution", but only got as far as building a hangar. LTA Research is lucky that they can use an existing hangar rather than having to build a new one. At airship sizes, that's a pretty big investment.
America, where insulin [1], epi-pens [2] and a lot of other really REALLY basic but absolutely vital medications have been subject to usurious prices for decades.
I would add that it's a ridiculous situation where you cannot buy antibiotics over the counter "because of the risk of overuse", yet they are pumped into animals living in squalid conditions en masse.
I'm guessing the learnings from project loon are in play here. (loon proved that alphabet could 'fly' balloons around with no fuel just by adjusting the altitude, ostensibly as lower-than-space comms relays) If you can move bulk from anywhere to anywhere with (almost) no fuel you are on to a sure winner. iirc the 12 largest ships on the planet produce as much co2 as all the cars.
Some cyberpunk novel or another suggested you could engineer a structure where atoms surround a core of vacuum, making the assembly as a whole lighter than air. Cool idea, altho of course any piece that breaks off will float up into the atmosphere and become a hazard to powered air transport, so it would have to degrade after prolonged exposure to UV.
https://www.thecgo.org/benchmark/bring-back-hydrogen-lifting...
Here's a startup focusing on Hydrogen:
https://newatlas.com/aircraft/h2clipper-hydrogen-dirigible-c... https://h2clipper.com/faqs/