Airship-filled skies are a cliché of alternate history fiction, to the extent that were we to take them as literal samples of possible worlds, our own timeline could be accurately characterised as “The One Without The Zeppelins”. In the Sherlock Holmes story ‘The Adventure of Silver Blaze’, the famous detective notices “the dog that didn’t bark in the night”, which is of course an inspiration for Mark Haddon’s ‘The Curious Incident Of The Dog In The Nighttime’. Before I get too scattered, I want to ask the crucial questions: Is the general non-use of airships in our timeline relatively improbable? Does our non-use of them depend on an event which could easily have gone differently? In the jargon of alternate history fiction, what’s our POD – Point Of Divergence?
One reason we don’t really have airships nowadays apart from the occasional advertising blimp such as the Goodyear Airship is that because they were filled with hydrogen, they got the reputation of tending to explode. There were two reasons for using hydrogen rather than helium. One was that the mass of molecular hydrogen, or at least protium, that is, hydrogen-1, is only half that of helium and therefore it’s somewhat more buoyant, and the other is that helium is much more expensive than hydrogen because on this planet it’s much rarer, even though it’s the second most abundant element, making up something like ten percent of all atomic matter in the Universe. This is because helium does not readily combine with other elements and therefore rises after its formation through the atmosphere and ends up in space. However, unlike most other non-radioactive elements, helium is constantly being produced by the rocks of this planet. This is due to the fact that helium consists of neutralised alpha particles, which are pairs of protons and neutrons bound together and are a common emission of unstable elements. Helium is occasionally trapped in deposits of natural gas because the rocks above them don’t let the gas through, and this is the main source of helium for us. By contrast, hydrogen is readily available despite being lighter than helium because it combines easily with other elements, forming compounds such as water and crude oil, and in fact hydrogen is present in more compounds than any other element, even carbon. It can fairly easily be extracted by passing a current through acidified water, or by the action of strong acids on metals. It’s also the most common element of all, comprising around nine-tenths of all atoms. That said, its eagerness to combine itself with, for example, oxygen, also known as combustion, does make it potentially very hazardous.
There are currently only about two dozen blimps in the world, of which only half are operational. The Hindenburg disaster put paid to their use as passenger craft, and was not the only calamity. The R101 above, publicly-funded rival of the private R100, was on its way from Bedfordshire to Karachi when it crashed in France, the immediate cause being a sudden downdraught, although there was a major fire which killed most of the people on board. There were other factors involved, such as the possible lack of experience of the crew, and it put paid to any further attempts by the British to develop passenger airships. That was in 1930, and the Hindenburg crash was in 1937. Although the R100 was more successful, it made no more flights after the R101 crash and was decommissioned. However, by the time of the Hindenburg disaster, heavier than air flight had been much improved and the chances are they would’ve been superceded anyway.
Airships were the largest flying machines ever built. They were often over two hundred metres long, in other words the same kind of scale as ocean liners and supertankers. To me at least they have an immense romantic magnetism to them and it really saddens me that they didn’t, er, take off. It must have been an amazing experience to see a vehicle of that size fly over, and an even more remarkable experience to fly in one. I have to confess that I don’t know what improvements were made in heavier than air craft which would’ve enabled them to take over anyway, so right now I can’t answer the questions I posed myself above. However, clearly if heavier than air flight had been developed later this would have extended the career of airships.
Airships are slower than planes and need to be much larger to carry the same weight because the entire mass of the airship with passengers and cargo has to be lighter than the equivalent volume of air. Air has a density of 1/800 that of water. The largest airship ever built was around two hundred metres long and thirty-three metres in diameter. Assuming this to be a cylinder, the equivalent weight of air is 206 tonnes. This is the maximum weight an object of those dimensions can have in this planet’s atmosphere at sea level and still be passively buoyant, as opposed to having to use some other force to hold or push it up. A cylinder of that size consisting entirely of hydrogen would weigh almost thirty and one of helium sixty tonnes. This gives the designer a completely laden additional weight of only 176 tonnes in the first place and 146 in the second. There are other possible lifting gases, the most obvious being ammonia, methane and neon. Neon weighs about half as much as air and is very rare on Earth despite being the fifth most abundant element in the Universe because like helium it doesn’t combine and it’s light enough to leave the atmosphere easily without being easily replenished. Methane and ammonia both weigh about the same as neon, but methane has the same drawback as hydrogen of being highly inflammable. Ammonia is quite toxic but only slightly inflammable and, like methane, can be produced by biochemical processes, although the Haber process is usually how it’s produced industrially. Even so, an ammonia-filled airship of that size has something like a hundred spare tonnes for the structure, cargo, fuel and passengers and to me looks like the best option. It might also be feasible to improve the buoyancy of an airship by turning it into a giant wing which provided some lift, or possibly by heating the lifting gas to reduce its density, which would then need to be kept away from oxygen.
Airships have one major advantage over planes – fuel economy and everything which follows from that, namely much reduced pollution. There are even pedal-powered airships, although much smaller than the Hindenburg or R101. This could lead to their adoption for air travel over planes at some point, although their speed is somewhat problematic as they’re much slower. Another advantage is that they can transport people and goods to inaccessible locations without the need to build roads or rail and without disrupting points between with noise and other pollution to the same extent.
Zeppelins were used for air raids in the Great War. This photo shows the aftermath of the sort of accidental bombing of Loughborough on the night of 31st January 1916, which killed ten and injured 150. This happened because the blackout had been enforced successfully in Leicester but not here, making us an easy target. The bombs were dropped on the Rushes. Apparently they thought they’d hit Liverpool and Sheffield, which strikes me as very odd because it’s hard to imagine that their ability to navigate was that primitive at that point. I’m probably missing something.
Air raids of that sort were ruled out in the Second World War due to the advances in aeronautics and the fact that slow airships filled with hydrogen were ridiculously vulnerable to attack. War also tends to give technological change and to some extent progress a boost, meaning that the War dealt the death blow to the already ailing dirigible. Hence with a little tinkering with the Treaty of Versailles, World War II could have been prevented and this might have slightly extended their lifetime, although things were already looking grim for them at this juncture. But without the War, perhaps they could have lasted into the 1950s, though a rather different 1950s than in OTL (Our Time Line).
There are niche applications for airships, such as the advertising function of the Goodyear Blimp and cruises and safaris, but Zeppelin World has widespread airships all over the place in the present day, so that doesn’t cut it. There is a slight advantage in the availability of lighter materials in recent times, and another is that they can moor over urban areas, unlike planes which for a long time needed to land away from cities, although this requires them not to explode. If they used for tours, it might make sense for tourist hotspots like London to have dirigible-filled skies, so the scene near the start of ‘Rise Of The Cybermen’ is realisable but not necessarily Lumic travelling there by airship, which suggests that they’re a routine, though possibly luxury, mode of transport. This is cheating though, because we’re clearly supposed to imagine widespread use.
Maybe the situation could arise by slowing the development of planes rather than accelerating that of airships. This would probably need a serendipitous discovery or two to go the other way. Again I don’t know enough about the history of aviation to suggest such a change. Or, maybe it could slow for social or political reasons. For instance, just as a major disaster was a minor factor in the end of airships, something like the early development of passenger planes resulting in multiple crashes, or maybe even an early 9/11-type scenario, would result in a taboo surrounding planes. A third possibility is lobbying or the failure to discover fossil fuel resources. On the whole, like my Caroline Timeline, an apparently simple change in the present day can only happen due to multiple changes in the past and vice versa.
Hence a series of PODs could lead to airships being routine, at least in niche uses, steadily later. The Treaty of Versailles being altered to be more sympathetic to the losers would have prevented Nazism, the Second World War and the Cold War, and as a side-effect, slowed the advance of heavier than air aviation, probably allowing a dirigible-dominated 1950s. The use of helium rather than hydrogen could also be a factor here, though only a minor one because in fact the Hindenburg disaster was only the final nail in the coffin. Conversely, early development of heavier than air passenger flights with a series of crashes would put the public off planes, although it might just make them generally more fearful of flying. A “helium lobby” active in government, fewer fossil fuels being found, environmentalism taking off earlier, all of these things could have propelled them further forward.
Or, it could just be as simple as Thomas Cook deciding to invest in airship cruises and tours and successfully marketing them, meaning that the more picturesque touristy parts of the world would just have them without a general adoption for more routine purposes. This, in the end, is probably the simplest scenario.
When it comes down to it then, we aren’t “The One Without The Zeppelins” at all. The ones with them are the odd ones out, not us.