Airships are cool, and one of the only vehicles that benefits of the square cube law as it can carry more weight if it has more volume of lifting gas. This got me thinking about what other advantages abd disadvantages you get based on an Airships size. What benefits are there to having a small airship versus a large one? What benefits does a large airship have over a small one?

To get a singular answer I want to focus on a general comparison:

What are the advantages and disadvantages of a large airship compared to a small airship?

To illustrate what I'm after, I would like to know the differences in capacity, short/Mid/long-range flight, maneuversbility during different weather etc.

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    $\begingroup$ I do not usually ask this but why is this a world building question? Seems a legit aviation question to me. $\endgroup$ – Ville Niemi Mar 26 at 12:05
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    $\begingroup$ @VilleNiemi same reason why questions about body armor, rail- and coil-guns, fusion energy, space construction and more ends up here rsther than somehwere else: you want to construct a world with it. I've seen multiple questions concerning floating cities, canon-wielding medieval Airships and aerial bombing campaigns that could have used information about what size does for an airship. I personally would look to worldbuilding for my questions rather than aviation as it concerns a far broader and fantastical range of options that "real" aviation wouldnt think off. $\endgroup$ – Demigan Mar 26 at 13:08
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    $\begingroup$ Please explain what a "small" airship is, and what a "large" airship is. Historical practice suggests that the LZ 127 Graf Zeppelin (237 meters / 776 feet long, 31 meters / 100 feet diameter, 105,000 cubic meters, 60 tons useful lift, 5 × 550 HP engines) is the smallest airship making commercial sense. $\endgroup$ – AlexP Mar 26 at 14:17
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    $\begingroup$ @AlexP why would that be necessary? It doesnt matter if the big airship is 1% bigger or 2000% bigger, what matters is what characteristics would become more advantageous and what would be disadvantageous. $\endgroup$ – Demigan Mar 26 at 14:38
  • $\begingroup$ Agreed that LZ127 was the smallest commercially viable size...90 years ago. But I'm unconvinced that is a good data point to guide decisions today. $\endgroup$ – user535733 Mar 26 at 15:21

The most obvious answer to your question is lifting capacity.

At the end of the day, with the exception of drones that are designed to be as small as possible while lifting a set weight (usually a camera), aircraft are designed and built to lift as much as they possibly can. The point of that is the same reason that cargo ships are getting bigger and bigger now that cargo has been standardised around the shipping container; carrying more units means that the fuel and time (read as wages for crew) required to do so is spread across more paying customers, or at least more freight. This is the reason for planes like the Airbus A380; if you have enough passengers per day to fly two (say) 747 jumbo jets to the same destination, then ultimately having a single plane that can carry them all makes sense even if it uses 150% of the fuel as you're still doubling the fares you can charge and you only pay for one air crew on a single flight.

To that end, meet the Lockheed Martin LMH1, a prototype for a new range of heavy cargo airships. According to the article, this prototype can carry 20 tonnes of cargo and 19 passengers, but future models could be scaled up to carry up to 500 tonnes, albeit with 800m lengths.

The fact that a company like Lockheed Martin is investing in large scale airships even as proofs of concept tells you that there is a commercial benefit to these designs. If you're moving cameras around, then going small makes sense. But these things can carry (say) massive amounts of cargo through impassible terrain for instance to supply people cut off by floods, forest fires and any other manner of natural disaster. For that reason alone, it seems like a good idea to go large on airships.

  • $\begingroup$ It seems to answer the question but not entirely. Maybe I should expand on what I'm after. You've answered "large ships can carry more weight and cargo" with a great example, but what about how they handle in different weather conditions for example? Does the large ship risk more structural problems during harsh conditions? Does the large ship have an easier or harder time maneuvering with lots of wind? $\endgroup$ – Demigan Mar 26 at 13:14
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    $\begingroup$ @Demigan while you have a point, I actually wrote up some of that and decided to cut and paste it into my answer on your other question. The reason I did that is because your question about the upper bound of scale of airships seemed to me to be the appropriate place to mention all that otherwise this would effectively be a duplicate question. $\endgroup$ – Tim B II Mar 26 at 13:18

Disadvantages of size will be grouped around housekeeping:

  • Hangars are more scarce,
  • mooring is more difficult,
  • repairs are complicated by increasing lack of facilities.
  • Volumes involved (bladder, cargo, fuel) become a headache, i.e. ingress and egress happens through areas (square) while the mass is governed by cube, so the mass flow needs to get higher, or you need linearly more time for related actions: fueling, loading/unloading, filling/deflating
  • Market is smaller for bigger things.
  • Accidents grow more catastrophic (economically: how to haul the carcass back?, victims/damage: one leaky bladder just suffocated a whole village/ one runaway 10km zepplin just got caught against the NY skyline in a storm, toppling the lot).
  • While the airship has no problems supporting it's size, the cargo is not necessarily so sturdy - many supermassive things (supertankers etc.) are built to be supported on a wide area (water, ground), not from individual hardpoints. So the airship needs cradles for that, and techniques to get the cargo onto them.

Advantages of size will group around technical issues - At same ratio of power to lift (which is not true irl, large blimps usually are relatively weaker, because you can get away with it (qed), economics at work) bigger is better in :

  • handling (air forces needing to be overcome scale with either length or area), both only growing in square with size, while lift (~power, remember) goes as cube
  • resilience (lifiting gas is lost over the surface (square) and available in volume (cube); Crew is bigger, so more redundancy;)
  • range, (corrolary of the other points)
  • speed, (Reynolds number grows with linear size)
  • acceleration (as lift/power is defined as equal, the only variable is air resistance, going back to square/cube)
  • lift (most obvious last - but also note that this burns you on the economics: if you are capable of lifting a refinery, lifting a petrol truck will not cover the bills, and fetching petrol trucks weighing as much as a refinery will mostly generate overhead).

Adv./Disadv.? - Note Not sure how to class this one: As your lift grows by cube, the 'attachment area' for loads only grows by square. If we now think about all the super massive things that humans built (industrial plants, skyscrapers, ...) they usually are not simply 'scaled up' from smaller versions (an industrial plant my be 1km wide, 50 m high, so scaling it down to the 10m length of a garage, it would be only 0.5 m high; Skysrapers would be chubby smokestacks if scaled to the size of a family home) - so the reality of 'things our giga-airship might carry' is not centered around stuff whose mass goes as the cube of their length; On the other hand, our giga-airship is not real either, so it might be disingenous to assume that in a world of such ships there would be no 'scaled-up fuel truck'-kinda-refinery in need of carrying - and that would be a problem because our airship would have the raw lift, but would be unable to link to the refinery because of insufficient area to put tow-lines.

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    $\begingroup$ Could gas from airship's airbags even suffocate a village, if it's lighter than air and goes up? $\endgroup$ – Mranderson Mar 26 at 16:46
  • $\begingroup$ @Mranderson imagine a kilometre-long airship loosing steering and being pressed against a steep mountain by the wind (apart from a kilometre long something now being forced against the ground, which could create other fatalities), being ripped open at multiple locations. I can see a bubble of a mixture of air and lifting gas flowing uphill, clinging to the mountainside, suffocating a village there. $\endgroup$ – bukwyrm Mar 27 at 7:11
  • $\begingroup$ No, it would go up. To suffocate people the gas would need to concentrate enough to replace oxygen. Concentrated lifting gases just go up, they do not cling. It is very hard to get suffocated by them outdoors. A slower leak that does not create a powerful suction upwards could make people speak funny and older iPhones freeze up. $\endgroup$ – Ville Niemi Mar 27 at 7:37
  • $\begingroup$ @VilleNiemi It might 'clling' I refer you to the topic of gravity flows - but for the sake of argument, just imagine the village is suspended under another super airship going over the foundered one. My point is: Big volumes of X > greater danger (or danger to more people) than smaller volume of X $\endgroup$ – bukwyrm Mar 27 at 8:08

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