Commentary, We Sail Off To War No. 3

Bally Hughes is a pun on ballyhoo, not a reference to certain anatomical features1.

At this point I’ve referenced all of the weapons systems we’re likely to see. We have impellers (which you might know as railguns): two parallel rails, a projectile in between them, which is accelerated by the forces generated by running a current through the rails. Hermes mounts one on the centerline. They’re the turrets we see on Resolution, each of which is roughly Hermes‘ size. Battleships and battlecruisers of more recent vintage tend to mount a few of those as primary batteries. They propel a very light projectile at high velocities, in the 150 to 200 kilometer per second range, relying on kinetic energy to kill their targets, and due to the size and therefore sluggishness of their mounts, are generally long-range weapons.

We have hybrid impellers: the main batteries on Hermes, Warspite, and the Vengeance-class cruisers (in 20cm, 20cm, and 38cm versions, respectively). These use a good old fashioned chemical charge to build up initial velocity, and impeller rails to add some velocity onto the top, up to a maximum of five or eight kilometers per second. Their projectiles are larger and generally carry a high explosive payload of some sort. You fire them to hit the radiators; knocking out a ship’s radiators will basically knock it out of the fight. Any damage they do to the hull is extra.

We have missiles: heavy anti-ship weapons, with an effective range of lots. Engagement ranges for the two flavors of gun reach one or two thousand kilometers for impellers, and three or four hundred kilometers for hybrid impellers; missiles can be fired at just about any range, since their engagement profile is to build up a closing velocity of a few hundred kilometers per second and coast until they reach the enemy’s point defense range, at which point they maneuver evasively to impact. There are two major warhead types; explosive, for targeting radiators and hulls, and EMP for targeting computer systems. Killing a ship’s computers (or forcing them to shut down due to high levels of electromagnetic interference) is a great way to limit its effectiveness.

And we have point defense: a combination of microwave lasers and small-caliber high-velocity hybrid impellers (the standard caliber is 3.7cm). When a maser hits a target, it induces electromagnetic interference. Shooting a maser at a missile probably won’t burn through until fairly short range, and maybe not even then (it’s not an easy problem to keep a maser steady on target for the second or two it would take). It will wreck the electronics in the seeker heads and maneuvering control system, and the ideal missile after a few maser hits is a straight-runner. The hybrid impellers target the straight-runners to conclusively kill them (many missiles include a system to turn off their electronics when under maser fire, and flip them back on when they’re close for a surprise attack), and anything that gets closer to prevent the ship from taking hits.

So, the very edge of effective engagement range is about 25,000 kilometers thanks to missile fuel considerations and maneuvering windows. Considering starship sensors of various sorts range out to about four or five million kilometers2, you can see why Winston is surprised that Weatherby wants to lay a trap.

I should note that this is a much harder setting to write in than Lägraltvärld: there, I only have to worry about being internally consistent. Here, there’s physics to worry about. If I have time over the weekend, I plan to do some work on writing myself an intercept course solver. This will require me to relearn linear algebra and/or differential equations, neither of which am I much good at. Altogether more likely, I’ll avoid the problem entirely, rely on approximations (or repeated refined approximations), and eventually return to Lägraltvärld with a great sense of relief3.

In other news, there’s now a Facebook sharing button. I’m not all that good at this writing dealio, but if you think I’m mediocre enough to be better than the average Internet reading material, feel free to let people know.

1. Although I presume he’s got quite a pair of those, too, to acquire a nickname as he’s apparently done.
2. This isn’t the whole of the story, though. Detecting a ship at four million kilometers is possible. Identifying it as a warship is much, much more difficult, particularly since space (at least around a big center of industry like Argo) is pretty darned busy.
3. Burying my possible delays in a footnote: before I go on with writing more of Lägraltvärld, I want to go back over it and update my encyclopedia files. One of the issues I’m having with getting more of it written is that I’ve already got a pretty decent number of characters, and at least a few more major or recurring characters left to introduce, and a detailed history of past events in my head. Some concise reference will really help me keep it consistent.

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3 Responses to Commentary, We Sail Off To War No. 3

  1. Gabriel Schwartz says:

    Must resist tropes link……………

  2. Fishbreath says:

    With a system of 15 linear equations, it’s possible to solve an intercept course problem without calculus. However, it took me half an hour to do a one-dimensional case by hand, and Mathematica utterly failed to give me the solution I worked out.

    Rolling my own solver may be necessary.

    • Fishbreath says:

      It turns out this is not actually the case: it’s a boundary value nonlinear partial differential equation problem. That’s a lot of adjectives. I don’t know how to do one of those. I don’t even know how to set it up. It would probably be a good thing to learn.

      However, I do have the power of computers and repeated approximations at my disposal. My computerized intercept plotter is going to be a fairly simple simulation of the motion involved, and I’ll just vary the time until it’s obvious we’re not getting any closer or the intercept works.

      The funny thing is, computationally that might actually be faster than solving the differential equations.

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