Friday, 24 July 2015

Airships!

See? They're romantic! Image by Deltamike.

Like a lot of people, I kinda love airships. There's something magical about them; perhaps more than any other form of transportation, they feel like something from a fantasy novel, rather than from real history. Probably it's the weightlessness, the sense of effortless movement, which makes them feel as though they transcend all the ordinary laws of mass and motion. For planes and helicopters, take-off is a strenuous affair, all roaring motors and spinning propellers. An airship just... ascends.

In RPGs, though, I've learned to my cost that they need to be handled with care. Give PCs access to efficient air transportation and you've basically handed them an excuse never to trek through a dangerous wilderness ever again; they'll just fly straight to where they're going, skipping whatever's on the ground. You risk trivializing a lot of traditional monsters: anything without effective long-ranged attacks can simply be killed by raining missiles down on it from above. You trivialise obstacles: city gates, castle walls, and impassable forests can all just be drifted over. Geography loses its impact, which is a big deal in a setting inspired by central Asia: the landscape which had such a powerful effect on the history and culture of the region suddenly becomes an irrelevance. Why walk the Silk Road when you can just fly direct from east to west?

In ATWC, therefore, airships do exist; but they operate under a very heavy set of restrictions, which turn them into a specialised tool for dealing with specific situations rather than an all-purpose method of transportation. The basic concept is as follows:

1: Airships rely upon alchemically-produced lighter-than-air gas

These aren't just hot air balloons; their airbags are full of something like helium, non-flammable and lighter than air. This is primarily manufactured by the Serpent Folk; the Blue Folk, children of the element of air, also know how to synthesise it by magical means, but they're usually unwilling to sell it to outsiders. Manufacturing this gas requires a high level of alchemical expertise and extremely expensive components and equipment, which means that it's expensive: really, really expensive. Getting enough gas to fill the airbag of an airship can easily cost more than building the damn thing in the first place; and given that some gas is inevitably lost on every journey due to routine wear and tear, transporting a given weight by airship is something like one hundred times as expensive as sending it by horse or boat instead.

2: Airships are very lightweight and thus very fragile

Because of the astronomical cost of lighter-than-air gas, airships are built to be as lightweight as possible; every pound shaved off the weight of the hull is a pound that doesn't have to be paid for in additional gas. The result is that most airships are extremely flimsy: ultralight frameworks of wood and metal, covered in tightly stretched canvas. They can carry only the lightest of cargoes, and any kind of damage or collision will pretty much wreck them. Their airbags are covered with thicker canvas, but any serious projectile (a bullet, an arrow) will still penetrate it, causing a potentially catastrophic leakage of the gas inside.

3: Airships are very vulnerable to extreme weather conditions

Airships steer by means of sails, rudders, and small clockwork propellers to provide thrust. Because they're so lightweight, however, their ability to cope with stronger winds is very limited; once you hit anything stronger than a stiff breeze, you're basically going to go in the direction the wind is blowing, whether you like it or not. Given the strength of the winds across the steppe and the desert, this usually means that trying to fly anywhere except in the direction of the prevailing winds is an exercise in futility. Storms will simply wreck you unless you're very skilled, very lucky, or both.

4: Vertical movement is really tricky

Most vertical movement is accomplished by adjusting the angle of the sails, allowing the wind and the air currents to gradually carry the ship up or down; but when you want to change height now, the only option is to adjust the mass of the airship itself. Every airship carries a certain amount of weight to manoeuvre with. When the pilot wants to go up, he throws some weight overboard; when he wants to go down, he lets some gas (the precious, precious gas) out of the airbag. When he's reached his desired height, he needs to ensure that weight and gas are in almost perfect equilibrium. In theory, landing is just a matter of letting out a tiny bit more gas so that the airship as a whole becomes slightly heavier than air, and allowing it to drift slowly downwards. In practise, doing any of these things with a wind blowing is a nightmare, and usually ends up wasting far more weight and/or gas than you'd hoped it would.

Remember that landing on trees, or flying into them because you've been hit by a down-draft and have no spare weight to throw overboard, will rip your airship to pieces. Funnily enough, no-one ever tries flying airships over the taiga.

5: As a result of these four facts, airships are only ever used for high-risk, high-priority transport

The net result of these limitations is that airships are basically only useful in one set of circumstances: if you want to carry someone or something lightweight across a large overland distance, very quickly, in the direction not blocked by the prevailing winds, and you're willing to incur enormous expenses to do this while also being willing to accept a sizeable risk that the airship (and its passengers or cargo) might be destroyed by bad weather or bad luck en route. Most travellers and merchants will never use them, because it's much cheaper, easier, and safer to travel by land, instead. Examples of things that might be carried by airship include:

  • Spies and messengers carrying urgent messages back to their superiors. (None of this 'carrier raven' bullshit. Messages are carried by people.)
  • Urgent deliveries of people or objects during moments of acute crisis. (Rushing medical supplies to a plague-struck city before the disease spreads, for example.)
  • Elite teams of spies, assassins, and special forces being air-dropped on one-way trips deep into enemy territory.
  • Extremely valuable, highly-perishable luxury goods being raced from their place of production to the homes of customers willing to pay enormously high prices for them.
  • Eagle-eyed scouts with telescopes scouting out the movement of enemy armies in wartime.
  • Thieves or other criminals who need to make a really quick getaway.
  • Small teams of crazy adventurers trying to reach somewhere which is totally inaccessible by any other means.
Airship by aninael
It's all worth it for the view, though. Image by aninael.
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You can use airships for military purposes. You can load up a few barrels of gunpowder, fly directly above your enemies, and drop them from a great height. You will want to make sure you get the fuse length exactly right, though, or they'll explode harmlessly in mid-air. This is most effective on stationary targets, such as besieged cities, but even then the efficacy of each bombing run is strictly limited by the small amount of ammunition that can be carried on each flight. Dropping big rocks is right out: the weight is just too much for an airship to deal with. Most generals stick to using their airships for scouting purposes.

* * *

Anyone can learn to fly an airship with a bit of practise, but only a traveller can safely and reliably pilot one through combat conditions, strong winds, etc; their extraordinary sense of weather, movement, and distance makes them far better at it than any other class. Anyone else will need to make lots of Wisdom and Dexterity checks whenever things get rough. Even travellers will want to avoid flying in extreme weather if at all possible.

* * *

You can't use an airship to fly straight to the Lost Temple because you can't afford to buy that much Magic Airship Gas from the serpent folk, and because the Lost Temple is halfway up a storm-wracked mountain into which you are certain to crash your airship, and because the chances of your ship surviving to carry you back again are totally minuscule and its tiny cargo capacity won't let you pack enough supplies for the lengthy return journey on foot. Just go by horse instead.

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If someone is shooting at your airship from a range where they might actually hit then you are all fucked and you need to either get away from them or get off the airship as quickly as possible. Your airship is stupidly fragile, and every bullet-hole in the airbag is going to cost you a fortune in lost gas. If you have to kill them, then either do it from an enormous height (so they can't shoot back) or land and fight them on foot. Trying to engage them while riding a flying canvas deathtrap is a terrible idea that will get you all horribly killed.

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Mid-air battles between two airships are essentially the world's most expensive version of Russian roulette.

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Airships are a great place to take someone for a first date.

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