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I want to create a world where there are large airships, but the technology available is still basically pre industrial. I don’t think there is any way to achieve this without using magic (if you can think of a way please let me know extra points!). The world is an Earth analog.

But I’m not a fan of magic so I want to minimize its use. What is the best way to incorporate a little essential magic to enable my airships whilst preventing widespread industrialization by magic? I also want to make it as easy as possible to suspend disbelief so a simple magical effect that ties in with the real world seamlessly would be good.

The ideal set up would minimize the use of magic and maximize the use of real world non magical mechanisms as far as possible. A poor solution would involve extensive, varied and arbitrary magical interventions to make it all work. Such as a magical lifting force, a magical moving force with a magical fuel supply and so on.

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    $\begingroup$ What is the lift capacity and range that is needed for your scenario? $\endgroup$ – GrumpyYoungMan Dec 8 '20 at 21:00
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    $\begingroup$ I hesitate to be too prescriptive, but it would be good if it could do 2000 miles with multiple tens of tonnes payload. But if anyone can come up with a really good idea for something a bit less then fine. $\endgroup$ – Slarty Dec 8 '20 at 22:44
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    $\begingroup$ Please indicate specifically what you mean by pre-industrial, which by itself is every moment in time between T=0 and about 1870. Everybody's assuming much closer to 1870 than T=0. $\endgroup$ – JBH Dec 8 '20 at 23:35
  • $\begingroup$ Yes much closer to 1870. No or very few engines only water, wind and animal power. $\endgroup$ – Slarty Dec 8 '20 at 23:44
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    $\begingroup$ Wow, the answers here are full of a lot of hot air!! It's also vaguely plausible that Leonardo Da Vinci's followers could have advanced some of his designs to the state of "barely feasible". $\endgroup$ – Hot Licks Dec 9 '20 at 18:11
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You don't need magic to explain pre-industrial airships, just more abundant and accessible sources of naturally occurring helium than real Earth has.

Hot air balloons are (arguably) pre-industrial; certainly they require only Renaissance-level technology to manufacture. Your limitation there is the fuel; to get a big enough hot-air balloon to consider it an airship, you need a fast-burning fuel which means having a patroleum industry, or at least an advanced coal industry. Thermal Airships also have a number of drawbacks.

However, helium airships remain desireable, and are limited mainly due to current shortages of helium. But if your pseudo-Earth had multiple natural gas pockets with large reserves of helium, and some of these were close enough to the surface to be reachable via pre-industrial mining techniques, then you could have a source of helium for airships.

There are some handwavy aspects to this (like, an Earth with more helium would also have more radioactive elements near the surface, which would have numerous other effects), but IHMO it beats inventing a whole system of magic.

This also gives you some story hooks, because control of the helium mines would be a source of wealth and politically contentious -- likely even a cause of wars.

There's three other aspects to the airship. One is a frame, which is the easiest part. Laminated woods were quite advanced by the late 17th century, and work quite well for light but strong frames, so much that the largest airplane in the mid-20th century was built that way. So, likely fantastically expensive because of the amount of work involved, but possible.

The envelope is more of a challenge. Helium leaks fast, and we're talking cloth here. Rubberized cloth existed late pre-industrial, but would be quite heavy. I don't know enough other materials science to say whether other cloths available in the 18th century (like silk) would have been able to retain helium sufficiently well. Although again, losing altitude can be a story hook. (per Sebastien below, Goldbeaters Skin would have worked, although would have required slaughtering huge herds of oxen)

The final bit is propulsion, which would most likely be fan-shaped "oars" driven by humans, unless you want to advance the invention of the rotary fan by quite a bit. This would effectively make your airships "floating triremes", and they wouldn't be able to go very fast, or take on any kind of headwind to speak of.

That's the "no magic" solution. If you want "minimal magic", you'd be applying it in 3 places: the extraction of helium, the gasproofing of the envelope, and propulsion (like making those fan-oars more powerful than they really are).

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    $\begingroup$ And I'm thinking you could use magic to concentrate helium. Then the ships aren't magic. but still have materials not normally available at the time without. Still magic, but minimalist. $\endgroup$ – DWKraus Dec 8 '20 at 21:20
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    $\begingroup$ Yeah, although if I were going with magic I'd say generate hydrogen. That way you'd have both loft and fuel. $\endgroup$ – FuzzyChef Dec 8 '20 at 21:22
  • $\begingroup$ Are you certain that you can make an airship with preindustrial technology, provided you have access to helium? $\endgroup$ – AlexP Dec 8 '20 at 21:22
  • $\begingroup$ AlexP: if you have specific questions you'd like me to address in my answer, feel free to ask them. $\endgroup$ – FuzzyChef Dec 8 '20 at 21:26
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    $\begingroup$ The early airships used goldbeater's skin as an envelope material. Though once again fantastically expensive at the scale required in a pre-industrial world, I'd argue it would still be achievable using pre-modern or Renaissance-era technology. $\endgroup$ – Sebastian Lenartowicz Dec 9 '20 at 8:54
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If you compare pre-industrial ships to modern ships you might scream in horror, even for those used when cruising the oceans. Why not using the same approach with your airships? There is no OSHA or similar safety-worried entity around.

Hot air balloons were invented at the dawn of industrial revolution, just go big on those, and have them pushed around by winds. Maybe allow some very limited maneuvering with hand or beast propelled propellers. Again, not too different from those ships which in case of necessity could be moved by rowing sailors.

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    $\begingroup$ I had the exact same thoughts while reading the question. A primitive airship migt also be built by tying a lot of small balloons with rope, and having a single big basket below. You'd need a hell of a hack with tubes to send hot air to each individual balloon. Maybe the magic OP needs only serves to make such things safe and nothing else. $\endgroup$ – The Square-Cube Law Dec 8 '20 at 20:46
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    $\begingroup$ Ballons are not airships and airships are not ballons. Yes, they can make balloons in a preindustrial world; after all, they actually did make balloons in the preindustrial world. Myriads of them. In China. $\endgroup$ – AlexP Dec 8 '20 at 21:24
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Quite a challenge: You need large quantities of lightweight metal (aluminum, usually electrolyzed from bauxite), motors and fuel for the powered flight, lifting gas, and long-distance communication for the weather reports and distress calls.

  • You could keep bauxite electrolysis a tightly guarded secret. Nobody knows how that mining town in the valley does it, but they somehow get aluminum out of their worthless clayey rocks. It's a real head-scratcher.

  • Driving motors seem a bit far-fetched for pre-industry, and steam engines (with fuel) are simply too heavy and fire-prone to seem plausible, so you might need to push a bit more magic here. Wind-summoning charms or some such.

    Cool change: If the airship is using controlled-wind ballooning (instead of powered flight), then it need not be sausage-shaped anymore. Without the weight of motors and fuel, the passenger and cargo capacity increases. Finally, reasonable temporary control of wind makes takeoffs and landings much safer.

  • Lifting gas can come from alchemy or chemistry instead of electrolyzing water. Might want to add a charm to improve the gasbags...and to make them fire-resistant while you're at it.

  • Long-distance communications (weather reporting) can be done through some flavor of telepathy or sorcery, short-distance ground-to-air can use heliograph (day) or lantern (night). Distress calls can use good old signal rockets.

    In real-life history, bad weather shredded more WWI airships than combat did (that's why weather reporting is on the list). Fire from both causes was an ever-present concern.

    All of this does mean that airship travel will be expensive: That mining town charges a lot for aluminum, chemists need to acquire tons of hydrogen-generating chemicals, reliable wind-charms aren't cheap, and weather-stations and heliographs need to be staffed regardless of the traffic. However, that also means some your characters can have interesting-sounding careers as charm-sanitizers and journeyman heliographers and alchemists.

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  • $\begingroup$ Re: bauxite, something for the author to consider is that the Hindenburg weighed 215 tons, loaded. Even if only half of that was aluminum, in a pre-industrial setting, it would take a large strip-mine to acquire enough bauxite and electrolyzing that much without electricity would take, well, magic. A pre-industrial town isn't going to be big enough to produce such quantities. $\endgroup$ – GrumpyYoungMan Dec 8 '20 at 23:25
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    $\begingroup$ Just to understand how freaking expensive aluminium was before the discovery of modern industrial processes, there is an anecdote about a banquet held by Napoleon, where only the most distinguished guests got aluminium cutlery, the less distinguished guests had to contend with mere golden and silver cutlery. That's because aluminium could only be manufactured in laboratory in minuscule amounts. And we're speaking about early 19th century, not renaissance like in the question. $\endgroup$ – vsz Dec 9 '20 at 7:48
  • $\begingroup$ You don't need aluminum to build a rigid airship. The early Schütte-Lanz airships had wooden frames. $\endgroup$ – Mark Dec 9 '20 at 22:10
  • $\begingroup$ @GrumpyYoungMan Just wondering why you feel that mining enough bauxite to make 108 ton of aluminium would be hard, requiring "large strip mines"?... You need about 500tons of bauxite to make that much aluminium. This is a hole 1/7th as big as an olympic size swimming pool. Big for home industry, but trivial for even a smal village mining concern. $\endgroup$ – PcMan Dec 16 '20 at 10:46
  • $\begingroup$ @PcMan The question would be how much soil has to be moved to access 500 tons of bauxite? If it's 0.1% bauxite per ton of soil, that means 49,500 tons of soil has to be moved to a disposal site. That's a lot of labor in a pre-industrial era. $\endgroup$ – GrumpyYoungMan Dec 16 '20 at 16:53
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Lift them with hot air balloons powered by coal or wood fires? (probably multiple per large ship) That's not really very high tech. The only problem is that it takes a whole lot of balloon-volume per unit weight.

Another solution is to use large rigid containers and actually pump the air out of them to make vacuum, which could be done with 1600s technology on Earth (noting that "vacuum" really just means significantly lower air pressure than ambient in this context). You can also, of course, use the classic Zeppelin method of pumping a light gas into a balloon, which will have a lower density for a given pressure than air. In a fantasy world, this could be something that doesn't even exist on Earth, but, even on Earth, hydrogen is much easier to get than helium. Helium is super rare on Earth and mined from radioactive uranium deposits where it gets trapped underground, whereas hydrogen was isolated as early as 1671 by reacting acids with iron, and can even be made by reacting iron with steam (as Lavoisier did in the late 1700s), and is readily makable now by electrolyzing water, but is mostly made by heating up natural gas in the absence of air. It's also worth noting that methane, the main component of natural gas, is significantly lighter than air (as is water vapor/steam, which is probably more useful, so a steam balloon is actually more powerful than a hot air balloon, though has the problem that the temperature in it must stay above boiling).

Another classic fantasy solution is to have some kind of antigravity rocks that occur naturally in the world. That is technically "magic", and such rocks would have lots of uses and require some world-building explanations, but it doesn't really require anyone involved in making the airships to have actual magical powers, just to use available "magical" objects.

This second method should probably be used in combination with the first if one assumes that the weight of antigravity rocks cannot be controlled in-flight, since you would want your ship to fall down and not up, and it's unclear how you could make up-falling ship go back down when you wanted it to. Materials with either negative-weight, 0-weight, or some other fantasy response to gravity, space, and time could be used to make large structures lightweight, maybe only slightly above 0-weight so that the temperature (and therefore density) of the air in comparatively small balloons would control how fast it moved up or down and to what altitude it would settle. (Air density of both ambient air and air in the balloons drops as you go up because air pressure drops, so that affects things.)

It's also possible to make building airships easier by saying that the air on your planet is heavier. (I don't think lower gravity would help if balloons are used, although that does make powered flight, like what birds, bugs, planes, and helicopters do, easier.)

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    $\begingroup$ A reasonable idea. I like using rocks that are lighter than air. I think it would be easy to make such a ship go up and down. Basically the ship structure is mostly balanced by the rocks and auxiliary hot air is used to make it take off. Allowing hot air out would make it sink. $\endgroup$ – Slarty Dec 9 '20 at 9:22
  • $\begingroup$ If they're just lighter than air or even unaffected by gravity, rather than actively falling up, then they would have to be large in volume (to displace a large mass of air), not that much better than a hydrogen or helium balloon, which already remove most of air's weight from a volume (basically it's like using vacuum as a lifting "gas", but without needing the heavy walls to keep it from imploding). Floating up is about making your ships total/average density (total weight÷total volume) less than air. $\endgroup$ – H. H. Jun 1 at 1:59
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Looking at this, and depending on the type of large airship you'd like (real dimensions like the Graf Zeppelin or pure fantasy types with full up sailing ships attached), the magic you want (IMHO) would be something along the lines of weight manipulation (for obvious reasons) and some sort of air magic (to actually steer). The fins are there on real-world Zeppelin, but to my knowledge they actually steer with the propellers. Though Lockheed Martin and HAV are both working on hybrid designs that look promising (Lockheed, HAV)

To minimize the use of magic, it could be a crazily complex ritual, or they have to have specialized people physically carve complex (and highly secret or forgotten) runes onto the craft in order to achieve the desired effect. They could still need the gas cells to achieve lift but require the reduced weight magic to get the sizes you'd like. You could even use it as a theme, "Remember the Santa Catalina? The company skimped on the re-up for her runes, now she's gone down with all hands."

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Sea Breeze

Make the story fit by having it around the coast of a huge Island. Then hybrid-airship gliders can be kited into the air and surf the updraft of the sea breeze.

At night they could drop ballast and negative surf the downdraft of the night sea-breeze.

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Can you alter physics? For example, you can introduce some mineral that has negative mass, so that when set free, it does not fall down to Earth, but instead rushes up. Obviously it is found in mines, where a thick layer of normal materials prevents it from leaving Earth. Basically, this is similar to helium balloons mentioned in other answers, but does not require large hull, does not have leakage problems etc. Another approach may be the classical idea of a material that blocks gravity.


Or, if you'd better have minimal magic, you can have magic that works only as certain altitude. For example, due to some magical field any solid object would float in air when brought to a specific altitude. You can even invent some explanation why the magic field does not extend down to ground level — e.g. because its power is dissipated due to too many solid objects here, so at ground level the magic field simply makes objects weight slightly less than normal, and nobody notices it. Then you launch your planes with hot-air balloons (or maybe from a high tower, especially because the same magic field can make building high towers easier), and after reaching the needed altitude the plane will fly by itself.

You can even attach a long rope to the plane, and then have some person (or a team of slaves) on the ground that will simply pull your plane (though probably this is not really efficient). Or you can have oars, and note that you probably do not need strong oars, so you can have a large-area oars made akin to hand fans.

Landing will be done by moving the plane to lower altitudes (using same oars, for example), and then the plane will fall down. To make descent slow enough you can use also use hot-air ballons, or you may attach wings to the plane that will make it glide down (probably possible with middle-age technology), or you can use a parachute.

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    $\begingroup$ Magic is allowed so in a sense yes the laws of physics can be stretched. However the idea is to use the minimum magic possible. It would be very easy to say it's a magic airship, powered by magic energy with magic lift juice and magic everything job done, but that is not a good answer. I don't want to end up with rewriting the whole of physics because some unfortunate magical element introduces perpetual motion. $\endgroup$ – Slarty Dec 9 '20 at 18:58

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