Why Dirigibles?

[Anthony]

Originally Posted by Icelander

Does anyone have thoughts on alternative materials for airships, especially if magic or weird science is in play in some way?

Well, lots of options that would be derived from magical critters, such as giant spider silk. Details depend heavily on what magical critters exist in the setting. Also, control insects would probably make it a lot more practical to raise and harvest normal spiders.

[Rupert]

Originally Posted by Icelander

So if your climate is 'Northern European'-esque and most of your work force are born at TL2-3 (but in the process of picking up more advanced technical skills as world-/time-travelers try to use them create some kind of TL5+ industry and eventually bootstrap their way up to TL6-7 technology), what kind of fabric would be easiest to make in huge amounts?

That's linen or wool, because those are the native choices. Both have good and bad aspects for the sort of cloth you'd want for balloon envelopes - they are long staple fibres, so they are good for making strong fine thread, but both absorb water so they'll tend to hold moisture (and thus become heavy) in damp.

You could enhance aluminum if you could get tons of it. It's just that stories where the protagonists have higher TL knowledge than the local TL supports, it's usually easier to help the locals increase production of something they already know how to make (i.e. steel) than it is to go from hand-crafted ironmongery directly to aircraft aluminunum.

Even if the protagonists with higher TLs know how to make aluminum, can they make enough when they lack sufficiently advanced infrastructure and workers familiar with the metallurgy of any metal not in use at TL2-3?
Often, the first steps of industrial advances feature TL6+ engineers adopting modified TL4-5 industrial methods to be able to make use of local TL2-3 craftsmen and infrastructure.

It has to be steel and wood then. Making better steel, and better wood (i.e. plywood, which was used in airships) is much easier than making aluminium - that takes a serious electrical generation capacity, and making the specialised alloys is a mid-late TL6 technology. Mind you, high-grade steel is also a mid-late TL6 technology, but making it in smaller quantities to strengthen frames mostly of plywood wouldn't be so hard.

[Rupert]

Originally Posted by Anthony

Well, lots of options that would be derived from magical critters, such as giant spider silk. Details depend heavily on what magical critters exist in the setting. Also, control insects would probably make it a lot more practical to raise and harvest normal spiders.

Or to improve one's silk output, assuming you have silkworms.

[Fred Brackin]

Originally Posted by Icelander

You could enhance aluminum if you could get tons of it.

So why aren't you using RPM to make aluminum from bauxite? You'd be having to make real TL6 steel by magic anyway so why not go straight to aluminum?

It doesn't matter how much TL-2-3 labor and materials you can get. Those are all nearly useless to you. Even if you can use the local linen it's not available in the mulit-square meter quantities you need. The local wood is in short planks hewn into shape with adzes too.

Push the locals up to the point of making gunpowder and muzzleloading cannons if you have to have them doing something but airships are quite beyond them.

[Icelander]

Originally Posted by Fred Brackin

So why aren't you using RPM to make aluminum from bauxite? You'd be having to make real TL6 steel by magic anyway so why not go straight to aluminum?

Because the RPM magic I'm using works efficiently for stuff that can be expressed in folkloric and fable concepts, but gets exponentially more unreliable and inefficient the more you try to impose a scientific worldview on it.

Making fabric or canvas impermeable is a simple concept that anyone at TL1+ who has seen smoke go through fabric, but be trapped inside structures made out of something else, is familiar with. Saunas are TL2 and the locals already understand the concepts behind enclosing hot air.

So magically enhanced fabric that doesn't let hot air escape as easily is instantly grasped by the locals and using RPM to perform such a ritual is not only at any penalty, it's a Lesser effect.

Performing TL6 industrial metallurgy using RPM is done at a relative -3 penalty, the concepts involved are all unknown to local witch doctors and shamans (who then cannot assist in any way) and it is all Greater effects.

The result is that you could make comparatively tiny amounts of aluminum using magic, whereas you can get TL2 magicians to help you enchant much vaster expanses of wood or fabric, which can all be worked by locals as well.

And because good steel exists as TL2, even if only in small quantities, nothing about making steel in larger amounts or better qualities demands understanding of concepts foreign to TL2 magic-workers. Enchanting steel swords, for example, is something they already have stories about and they trade with TL3 societies that make extremely fine swords using magical craftsmanship.

Originally Posted by Fred Brackin

It doesn't matter how much TL-2-3 labor and materials you can get. Those are all nearly useless to you. Even if you can use the local linen it's not available in the mulit-square meter quantities you need. The local wood is in short planks hewn into shape with adzes too.

In a couple of years, you can get the locals to make linen and wood to your specifications. Closing the joints is a matter for good design and craftsmanship and then using RPM to get a seal over that.

I'm imagining that it would take more than a couple of years for higher tech colonists to build up a TL6 industrial infrastructure. They might want to explore their new world from the air before they do so and while RPM rituals to turn into birds do exist, birds can't perform cartography and surveying very well.

You'd start with balloons and then you'd want something steerable.

And as others among the colonists are building up your steel industry for a multitude of reasons, I'm assuming that you'll be able to make steel in quantities before you have the technology to easily make aluminum in similar quantities.

I'm not saying that you can't get aluminum using magic. I'm saying that magic is a poor tool to make either aluminum or steel and that the locals, who have used magic their entire history, do not use magic to actually mine the ore or to make metal, but only use rituals while forging an object from bronze or steel.

So using rituals to enhance materials already available is using existing magical 'technology', i.e. rituals that are already in common use. Making steel or aluminum using RPM would require researching TL6 versions of the TL3 rituals that exist, and probably wouldn't work as well even then.

Originally Posted by Fred Brackin

Push the locals up to the point of making gunpowder and muzzleloading cannons if you have to have them doing something but airships are quite beyond them.

Obviously, the locals would do as much of the simpler stuff as is possible, but if you want an airship, any kind of airship, before your industrial infrastructure is up to making large quantities of steel, isn't it almost axiomatic that you have to use materials that the locals are capable of working with?

[Fred Brackin]

Originally Posted by Icelander

isn't it almost axiomatic that you have to use materials that the locals are capable of working with?

That limits you to things that are rather simpler than airships. It'd take you years to work your way up to TL4 sailing ships.

Also, if I were GM'ing I wouldn't buy you explaining an invisible gas that's lighter than air to TL2-3 shamen. How can anything be lighter than air? Air doesn't weigh anything.

Whatever, you've made up your mind that this is doable somehow and don't want to hear what the real problems would be.

[Icelander]

Originally Posted by Fred Brackin

That limits you to things that are rather simpler than airships. It'd take you years to work your way up to TL4 sailing ships.

It would take years, yes. Note, however, that if you already have the scientific concepts and even designs made by TL7 engineers made to be easily constructed from materials and parts available from TL2-3 craftsmen, the earliest TL5 LTA vehicles are not obviously harder to make than TL4 sailing ships, if only because they are much smaller.

The very first flying things you make would be balloons, not airships, but, as noted, you would want some way to steer as soon as possible.

How do you do that?

Originally Posted by Fred Brackin

Also, if I were GM'ing I wouldn't buy you explaining an invisible gas that's lighter than air to TL2-3 shamen. How can anything be lighter than air? Air doesn't weigh anything.

The shaman doesn't have to understand the airship. They just have to understand the concept of fabric 'bags' that can hold air, like sauna rooms can.

Essentially, how to adapt rituals that are already used on earth, leather and wood for saunas and similar things to fabrics.

Originally Posted by Fred Brackin

Whatever, you've made up your mind that this is doable somehow and don't want to hear what the real problems would be.

It seems very doable, according to the stats from VE2. Of course, there might be complications beyond those material constraints, which probably wouldn't prevent you from creating something which could fly, but might have major influences on what you could use such airship for and what such designs might evolve into.

[Anthony]

Originally Posted by Icelander

Because the RPM magic I'm using works efficiently for stuff that can be expressed in folkloric and fable concepts, but gets exponentially more unreliable and inefficient the more you try to impose a scientific worldview on it.

Then it's not going to like airships much regardless, as the reason airships work requires concepts that are unfamiliar to folklore and fable.

[Icelander]

Originally Posted by Anthony

Then it's not going to like airships much regardless, as the reason airships work requires concepts that are unfamiliar to folklore and fable.

Very true.

Which is why no RPM magician could create airships, but TL6-7 engineers can. But that doesn't mean that the TL6-7 engineers can't make use of local resources, even if those resources are fundamentally strange to them and frustratingly hard to duplicate without having one of the primitive superstition-mongers present. Even if neither side entirely understands each other, together, they might be able to create ships that fly.

Besides, to TL6-7 people, airships are pretty fabled and already starting to amass mythology. Making airships in exile by relying on magical knowledge from locals probably strikes readers of TL5 to TL7 fantasy and science-fiction as entirely appropriate.

[tshiggins]

Originally Posted by Icelander

(SNIP)

The very first flying things you make would be balloons, not airships, but, as noted, you would want some way to steer as soon as possible.

How do you do that?

(SNIP)

Start small, maybe?

Use a hot-air gas-bag in a lifting body shape.

Sling a gondola beneath, with geared bicycle parts that drive propellers.

Only go up on calm days, or those with light winds. Use fuel to reach the desired altitude, and mostly rely on winds aloft to move the aircraft.

If the crew wants to go investigate something off their direct flight-path, they peddle like Olympic cyclists.

You want small crew-members with high strength-to-weight ratios, who are Very Fit. However, you only need one or two TL6-7 officers. The rest can be anyone small, strong and healthy enough.

It takes a looong time to map out a couple of hundred miles in each direction, but it gets done relatively safely, and mostly using the tech and magic you've defined. After that, the group has aerial reconnaissance and sentries -- which is a hell of an advantage.

For established routes, such a dirigible might make longer one-way trips, and crews rest up and re-stock before they return.

Best of all, for your purposes, it teaches the locals the needed concepts to build on later.

(It also means the most important parts, the gears and chains, are easily recoverable after they crash. Which they will. A lot.)