Building a world with airships that are powered by steam engines. Big boiler, water tank, lots of coal. Enormous engine room. Propellers, masts with huge sails. There are steam-powered automatons in this world, and they've replaced some forms of manual labor in the workforce. For example there might be automatons built solely to work in the engine room shoveling coal into the boiler's firebox.

In this world, I want to better understand the problems that can unfold in the engine room -- problems that might damage the airship, or make it impossible to take off or land. I think putting a lot of thought into the understanding of how problems can unfold will reveal convincing details about the world. So to that end:

When using a steam engine to power an airship, what is the most complicated steam-engine related problem that can happen? And what are the various ways engineers might try to solve this?

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    $\begingroup$ Just as an idle curiosity, what are the masts and sails for? And, seriously, what kind of steam engine are we talking about? Simple expansion piston engine, multiple expansion piston engine, turbine? Does it have a condenser? I suppose it uses superheated steam -- superheated to what temperature and pressure? How does the transmission look like -- rods, gears, chains? Does it drive constant or variable speed propellers? It's hard to imagine a serious yet tricky problem on an unspecified "engine", other than "the baricoque became blocked, so the poppystress relief of the zuckumber failed". $\endgroup$ – AlexP Apr 1 '19 at 21:19
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    $\begingroup$ @ClausV, welcome to World Building. It would help to better understand the engines. Is there a component of lighter-than-air? If so, there could be a problem with the lifting-gas generator. Are these winged graft? Maybe a balance problem (fore-aft, or port-starboard) would work for the story. Perhaps it isn't strictly an engine problem, but a navigation problem and the disagreement is about certain precision guidance maneuvers? Knowing more actually constrains the problem, and encourages greater creativity. $\endgroup$ – cmm Apr 1 '19 at 22:52
  • $\begingroup$ These are really good questions, thanks. Maybe I don't know as much as I thought I did about steam power. Doubly difficult to then try to get into the head of an airship engineer with technical expertise. I was imagining the engine looked something like a Wilesco D-32. But that's mostly for aesthetic reasons. Steam from the boiler would generate lift, and the masts and sails could work for maneuverability, like the masts and sails on pirate ships. I could probably use some help in making some more decisions to constrain the problem. $\endgroup$ – ClausV Apr 1 '19 at 23:05
  • $\begingroup$ @JBH thanks, noted. I have edited my post -- hope the question is a better fit now. Cheers $\endgroup$ – ClausV Apr 1 '19 at 23:13
  • $\begingroup$ Excellent, thanks! One of the tricks to this site is remembering to focus on the world (where many stories can take place). In the long run, it provides you with a broader scope of detail that often exposes ideas you didn't know were there. I have retracted my VTC. $\endgroup$ – JBH Apr 1 '19 at 23:16

Murderous Steam EVERYWHERE

Background: I worked in the Engine Room of a Nuclear Submarine... where we use a steam cycle to generate power.

One of the worst things that can possibly happen in a steam power engine room is the "Steam Line Rupture Casualty."

Basically, you are using high pressure steam to move turbine blades, so there's piping that moves the steam around. If that piping breaks - due to corrosion, over pressure, someone dropped something heavy on it, whatever - now the boilers are putting super-heated steam into the people spaces. Basically, now the whole system is attempting to cook the crew.

The classic answer is to remove the source of steam - you can vent it directly out of the boilers to overboard or you can just let steam pressure build up in the boilers, but the important thing is you have to stop the steam from entering the engine room. Otherwise everyone dies.

So maybe your crew is facing a situation where for some reason they cannot fully do the "right thing." A valve got stuck? The operator got cooked before he finished operating it? Now you've got conflict - how do you fix the system while the engine room is partially filled with murderously hot steam?

Do you put a patch over the damaged piping? Redirect steam around the broken piping (since your ship has redundancy)? Fix the stuck venting valve?

Who is risking their lives to do this? What kind of protective gear can you get them into in time? Do they need help?

The answers might not be clear, unless you're the Chief Engineer!

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    $\begingroup$ But the Chief Engineer's shift just ended and he/she is done for the day. (Technically- well done) $\endgroup$ – Michael Kutz Apr 1 '19 at 23:14
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    $\begingroup$ Looking at a comment in the question it seems that the idea is to use the steam for controlled lift by venting it to the gasbag, ie. the gasbag doubles as the condenser, so that is where they'd default to venting the steam? That valve getting blocked would be a serious issue since it wouldn't just prevent venting overpressure, it would also directly cause overpressure in the boiler and reduce lift. Although there would have to be a backup valve, surely. Probably unnecessary but since you have personal experience I'll just say that pressures and temps would be much lower here. $\endgroup$ – Ville Niemi Apr 2 '19 at 0:14

Let's start with some ideas.


  • The boiler is running hot and it's causing the surrounding structure to start to burn!

  • The heat of the firebox is causing a critical component (let's say a crankshaft or linkage) to begin to warp.

  • Coal dust in the firebox area exploded! How do we land this beast safely when there's little of the firebox area left?


  • We blew a gasket! It's bad enough we're losing pressure, but we're also running out of water.

  • A headwind is forcing the pressure up (technically not a pressure problem, but it can be a pressure solution. Wind against the propellers increases, which translates to force applied against the pressure of the steam — resulting in more pressure. You can't just lower the pressure or you start flying backwards).

  • Pressure expansion has forced the boiler against the containing walls of the airship — and they're starting to give way (structural integrity problem).

Engine linkages

  • Have you ever had the tires on your car aligned, only to have the mechanic show you the linkage and how the normally round hole is now an oval that won't allow the alignment to stay in place? Now, imagine that with the power of a steam engine. And every time that linkage rotates around, the situation gets worse. What will give first? The piston or the linkage? They're both taking a beating.

My favorite is the coal dust exploding

Why? Because it could be an issue of wind direction or outside air pressure that's keeping the dust from venting normally. Or a failure of the ventilation system or sabotage. Or a loss of control of the flamebox door. There are a lot of ways a story can build the threat of an imminent (and very real) disaster without having to experience the disaster right now! It depends on where your strengths as a writer lie. If you're great at writing moment-by-moment middle-of-the-disaster scenes, then one of the other problems would be better. If you're better at solve-the-puzzle-before-time-runs-out type of story, this is your baby.


Timing Issues

Most complex machines use timing belts to keep different components working together synchronously. When timing belts fail, it's usually a bad day (eg, the car engine seizes up). Something as important as an airship will probably have fail-safes in place, as any one timing belt would create a single point of failure, and it's not like you can just "pull over" (in a car), or pause the engine (in a boat) to fix it. The airship demands continuous action.

So what if, instead of something failing it gets off - but only slightly. These types of timing problems can be very tricky to detect. The larger, more complicated the system, the more difficult it may be to detect.

But it gets worse...

You mention automatons working in the engine room. What if they're all just slightly off? This could start by causing engine strain, a blown gasket here or there, and so on. The more off-sync the automatons are, the more catastrophic the problem. Ironically, this means the timing failure becomes it's own type of clock - if the timing issue is increasing by one millisecond every hour, and catastrophe occurs at ten milliseconds off, then in ten hours we're all screwed.

Solutions for timing issues are never easy, but the best way mechanics do this is usually "stop the engine, replace the belt, try again". Can't do that on an airship! Furthermore, even if one component can be stopped the idea of "stop the component, replace the belt, try again" may not work - the automatons are still out of sync! So the real question becomes "how do we get everything back in sync - and without stopping the automatons?"

Fixing the problem

Possible solutions include manually adjusting one piece at a time, forcing a failure on a component (forcing the backup to take-over), replacing an automaton with a human temporarily (assuming the human has good timing, and there are enough humans!), and so on. This helps with your central conflict, though, as you might not be able to try multiple solutions at once, so one of the two characters will have to give in.


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