Not necessarily slower than cargo ships, and possibly significantly faster. This paper claims that by using the jet streams a hydrogen blimp could circumnavigate the globe in about 14-16 days [1]. Google gives about 77 days to do the same on cargo ship. Of course there would be lots of details to consider on the exact route taken, but from first principles it seems plausible.

1: https://www.sciencedirect.com/science/article/pii/S259017451... 2: https://arimotravels.com/how-long-does-it-take-a-cargo-ship-...

I haven’t clicked the links to see if it’s mentioned because mobile, but it should be more than plausible - it was done 80 years ago; the Graf Zeppelin hydrogen lift airship did a round the world flight in five stages in about 15 days total flight time in 1929:

https://www.airships.net/blog/graf-zeppelin-round-the-world-...

(And it was the first air vehicle to pass 1,000,000 miles travelled, with no accidents, the first to reach the North Pole, the first regular transatlantic commercial flights, etc. all with 1920s technology and tens of thousands of hand-glued animal intestines for the lift bags)

The OP article suggests airships would be on par with conventional shipping freight for time. But in terms of capacity it makes an excellent point:

> Cargo airships would need to be big—bigger than the Hindenburg. Airships are blessed and cursed with a square-cube law: the drag of the airship, which is proportional to its cross-sectional area, scales with length squared, but the volume of lifting gas, and thus the gross lift, scales with length to the third power. Therefore, the lift-to-drag ratio, a critical parameter in aircraft performance, gets better as the airship gets bigger.

Shouldn't it scale linearly with length?

It's basically a cylinder, who's volume is heightPiradius^2.

Unless you're also making it wider and taller, it's not a cubed growth

The way I read it, is that drag increases ^2 for length, but because volume increases lift for airships (as opposed to other aircraft) you get this ^3 increase in lift by increasing length. So airship economy increases with size, as opposed to an airplane.

For the square-cube law, a cursory wiki search yields:

> The square–cube law can be stated as follows:

> When an object undergoes a proportional increase in size, its new surface area is proportional to the square of the multiplier and its new volume is proportional to the cube of the multiplier.

https://en.wikipedia.org/wiki/Square%E2%80%93cube_law

You're forgetting train (completely viable for China -> Europe), and the times where train isn't viable, a direct shipping express can be as efficient as allowing. What you quote with regards to 77 days is around the world but that isn't interesting for transport (that's interesting for leisure of just for the sheer competing; not transportation business).

What is interesting is the amount of time from large industrial ports such as say Singapore or New York to Rotterdam or Hamburg or Antwerp, the associated costs, and the risk of losing the transport (and its contents).

Either way, the last mile is the inefficiency with regards to carbon footprint. Ie. the transportation ship (and more so train) is relatively efficient; the last mile of the minivan delivering the one packet to you is the one which has the largest (relative) carbon footprint. To solve that, we need to invest in electric vehicles.

Train needs a massive upfront infrastructure investment, and isn't flexible for route when passing through politically unstable areas. China -> Europe needs to cross through at some point. Similarly, Africa -> Europe by train needs to cross in a politically unstable area. Being able to choose your route is very valuable.

The infrastructure for trains is already there (China -> Europe), its just static and therefore inflexible. It isn't going through politically unstable areas, just Russia. As long as you don't bet on one horse you're going to be fine. I don't know anything about trains from Africa to Europe. I believe China exports more than Africa.

Since we don't talk about last mile, they're competing with ship and airplane. For last mile, there's only the minivan/truck solution, though I'm not sure how widely adopted or sustainable drone delivery is as of now. A low carbon footprint of drone delivery would be a plus for adopting it long term.

A blimp still needs to cross those areas, and could be shot down

They could conceivably be very cheap if the gas pockets were mass produced. Everything else on board for propulsion and housing the pilot would be on the scale of a small prop aircraft. As long as the cargo can be easily managed, perhaps in a shipping container, then these would be easy to deploy en masse. They can land in any suitable field that has a crew on hand to guide them in with ropes. You might not even need pilots since these would be perfect targets for automation.

As for speed, you can optimize the shape of the aircraft and the position of the propeller for this. I've seen a number of videos that show surprisingly good performance for pointier fuselage with a pusher prop on the tail.

> Everything else on board for propulsion and housing the pilot would be on the scale of a small prop aircraft

It's likely that any cargo airship would fly for days/weeks at a time and would require at least 4 crew-members and everything they would need for the length of the voyage. So less a small prop and more something akin to facilities available on a yacht/Large RV.

> You might not even need pilots since these would be perfect targets for automation.

This would perhaps be the best solution

Why would it need crew? What would they do?

A cargo airship drone remotely controlled would get rid of most of the non-cargo mass requirements.

> -Also, much slower and lower cargo capacity.

I've always found airships and lifting gasses fascinating, but I'm not fully educated on this point. I thought that airships could potentially have very large cargo capacity, especially because larger airships increase aerial stability. Speeds would be slow, but I thought it was feasible to ship huge payloads, no?

-I know next to nothing of airships, but I believe your problem would be controlled flight; a huge airship has huge drag and once winds pick up, you'll soon run out of engine power to counter that drag - and all of a sudden you find yourself going the way the wind blows, which may or may not be where you intended to go...

(Presumably that same drag will cause problems for the structural integrity of the airship, too.)

I suppose winds will be the major problem for very big airships, but I believe there are lots of ways to deal with it. Using the wind in sailing is a known art. There could be technics to counter that? Or cruise along the wind and take a slightly different route. Or in general, probably you will have to take the winds into account a lot more, when planning blimps routes. And the winds are also different at different altitude.

And above a certain height, >10000 m, it is usually much calmer, but I think ordinary blimps cannot go that high. Different outside pressure etc. Possible to mitigate with adjusting the amount of hydrogen by compressing/releasing?