Friday, November 9, 2018

Generic Fleet Followup: The Battleship Slugfest (and more!)

After yesterday's post, Discord has been buzzing with questions.  I wanted to answer a few as best as I could, especially since it lets me dive a little into how I came to yesterday's conclusions.


  • How do various ships match-up against one another?
  • Destroyer vs Corvettes, which is better?
  • My assumptions

Mirror Matchups: Battleship v Battleship

I'm curious how well the various ship types do in mirror matches... A battleship on battleship mirror match interpretation would be nice, [s]ince I think battleships shooting battleships is a canon expectation -Kalzazz
This was literally the first match-up I worked out, it just felt a little like insider baseball, like most of the matches, so I posted some summaries.  The short answer to "How does a Battleship v Battleship match-up look" is "Like the Battleship v Carrier, with the Carrier in the role of losing battleship."

I wanted to take this as a quick opportunity to show you what my "behind the scenes" calculations looked like, so you can get a sense of how these will play out, so let's dive into some details about how and why I built my spaceships the way I did.

A battleship's design is to defeat other capital ships.  This is why it has the armor it does, including the configuration: the intent is to have extra "forward" armor and to face its opponent whenever possible, always trying to outmaneuver its opponent to keep that forward facing armor towards it.  It won't do this against corvettes or destroyers, but it won't need to because 7000 HP and 2500 DR are plenty.  This means "fighting other battleships" is definitely what its built for.  In practice, it amounts to a single +1 vs most capital ships (150 mph vs 100 mph, or move 75 vs Move 50) but it makes a difference.  It probably won't gain advantage on its opponent, on average, but it doesn't need to: it just needs to keep the other ship from gaining advantage on it.

First, let's talk accuracy.  Assume a crew skill of 12 and an ultrascanner lock on the opposing vehicle.  At a base, we're looking at an effective skill of 30 (Skill 12 + SM 13 + 5 from Radar and Targeting Computer).  If we can sit and shoot (the Attack maneuver) we've got a +9, for 39.  At Distant range, we have an effective skill of 20 and skill 24 at Extreme.  With our super-heavy turrets (3 turrets with 3 cannons each, or a total ROF of 9) we have an additional +1 and with our capital turrets (10 turrets with 2 cannons each, or total ROF of 20), we have an additional +4.  If we have  a full salvo against another battleship, we expect to hit an average of 6 times with our super heavies and 8 times with our capital cannons at Distant, and 8 and 10 times at Extreme.

Next, let's talk damage, given the number of average hits we have above.  We have a few scenarios, but let's look at two: the best case and the semi-worst case.

The best case is that the opposing battleship has its best armor facing you and it has its screen adjusted in your direction.  A battleship has a force screen DR of 10,000, giving it 20,000 when adjusted.  We'll treat this as fully-hardened simplified, just to keep the calculations quick. The capital-scale cannons deal an average of 1500 damage: 8 hits will strip it down to 8000 remaining DR; the Super-Heavies deal 2500 each: about 3 hits will mostly remove the last of the screens, and we have 3 hits remaining: on average, each of these is a minor wound (technically a Severity -4 wound).  By the book, we need to roll HT +4 to resist the accumulation of wounds, but I personally find a straight HT roll to be fine, and in this case we expect to only accumulate a more serious wound on average after 5 minor wounds (we succeed 80% of the time).  There's a risk of a Major wound (which equals a disabled system) but it's not high.  If we're at Extreme range, rather than distant, our 10 capital-scale hits will reduce the force screen to 5000, and two of our super-heavy hits will reduce the screen to zero, giving us 6 hits on the front armor, which averages a single major wound, or one disabled system.  This should address the first of Brett Tamahori's concerns: previously, in such an engagement, the "You're fine or you're dead" of the standard spaceship model, we were fine.  Now, we're at least marked by the encounter.  Something happened.

The semi-worst case is that the opposing battleship has Advantage and is facing your weaker armor and your screen is not adjusted.  This is only likely if your opponent is much more skilled than you (ie, a hero battleship vs a mook battleship) and you have to deal with enough threats that you can't afford to adjust your screen.  There are worse scenarios: your screens are down, or for some reason you angle your screens away from the enemy battleship (but why would you do this? The only reason I can think of is an even worse threat, in which case, this is no longer a battleship v battleship fight, but a super-weapon with supporting battleships vs a battleship).  In this case, we only need an average of 7 capital-scale hits, which means at both Distant and Extreme, all our capital hits will peel off the force screens.  Against frontal armor, a capital-scale turret is just going to Scratch it (severity -6), but against the side, it can deal a minor (Severity -5) wound, so at an extreme fight, we expect one minor wound, and at a distant fight, we expect 3.  The super-heavy turrets, now unimpeded by the force screen, will inflict all of their damage as minor (severity -3) wounds.  This doesn't seem any better, but Severity -3 is one step away from a Major (Severity -2) wound.  You need ~2900 damage to get a major wound, which is rolling a little better than 4s on all six dice.  So, a lucky hit on the side armor is already a major wound, so with one to three minor wounds already, and another (say) five minor wounds and one major wound from the super-heavy cannons at distant, or six minor and two major at extreme.  This likely translates into a few more failures, so we expect to see one or two more minor wounds accumulate into a major wound and another destroyed system, so we might see two to three disabled systems at Distant, and three to four at extreme.  This addresses the second concern of the "You're fine or you're dead."  Previously, such an encounter killed a battleship.  Now, we're in a bad way with some fires and things like worsened controls and less guns available, but these are things that we can, in principle, fix.  We're on a death spiral and probably won't last too much longer, but you'll need a several more turns of this to completely destroy the enemy ship.  We're not dead, but we're in a bad way.

As for the rest of your ships, it rather depends on how much damage you're dealing.  Capital ships v capital ships tend to be a measure of not whether you hit, but how many times you hit and how much damage you do.  Capital Scale turrets will inflict minor wounds on a carrier (so two carriers that for some reason decide to duke it out with cannons will slowly whittle one another way) and Corvette cannons will fail to meaningfully damage a destroyer (unless it gets lucky).

When it comes to corvettes, maneuverability plays a much bigger role.  You will simply get less hits in because you move more and because your opponent is smaller and has a better dodge.  A torpedo corvette can inflict minor wounds on the side armor of another corvette with its PD gatling blasters, and a heavy torpedo is an insta-kill for a torpedo corvette (Severity +4, or "Instantly fatal wound.")  Bombers are going to fare poorly against other bombers: they have light cannons compared to their armor and torpedos are easily dodged; their best bet are using missiles against one another. We've seen fighters v fighters already.

Corvette v Destroyer: A Matter of Mission and Scale

I'd agree that having a Destroyer automatically bumps you from "pirate" to "warlord"... If the rock-paper-scissors game has a failure point though, I think it might be the destroyer. It's supposed to be a corvette killer (and decent against bombers), but it feels like it might not be worth the 20 corvettes the same of credits could buy -- Miles
My favorite corvette
The Destroyer is a funny creature, and it (and the Torpedo Corvette) are the main reason I put the caveat about "these designs are more conceptual than final."  My original design was more practical, sporting at least one capital cannon and a few less corvette and PD cannons.  I also pondered adding missiles or torpedoes.  Eventually I settled on the design that I did because I wanted to see what an extreme anti-corvette focused capital ship looked like.  I don't think you'd actually see something this specialized in Psi-Wars, at least not on the scale of it.

The first thing that stood out to me about it was how big it was. It seems that if you want to focus on blasters, you're going to be a large ship.  Fusion reactors are big, impulse drives are big (I wanted to get it up to 300 mph, but that proved very impractical), armor is heavy.  If you want a ship with a lot of guns, it's probably going to be a capital ship.  This means your sweet spot for Psi-Wars ships are probably SM +12 to SM +14, which fits the aesthetics of Star Wars nicely.

You can make smaller ships with more compact design elements, though: hyperium reactors missiles, more expensive armor and hyperdrives and faster engines.  This starts to look more like a corvette than a capital ship, though, and I think there's definitely room for "heavy escort frigate."  It'd take some work to put together, but I bet you could put together an SM +9 to SM +10 "small, fast and lethal" anti-corvette corvette.  Such a vehicle would certainly be more accurate than a destroyer, when fighting corvettes, and it would have a better chance of outmaneuvering torpedo corvettes; you want to make sure you don't get hit by those heavy torpedoes, because something that can take out a battleship will take you out.

If the "heavy frigate" is better at this than a destroyer, why build a destroyer?  Well, the first answer is that you might not.  Miles might be right about the break points in the game. If I used the Relative Size Modifiers straight, the destroyer would fare even better, but I find it overly complicated ("Let's see, I'm SM +11 and you're SM +8 so I'm at -3 which would double to SM -6, but they're light turrets so it's -3..." vs "Capital ship vs Corvette, light turret, -5). This creates a break-point where bigger is almost always better until you hit a break-point in accuracy, then its better to stop before it: SM +9 is better than SM +11.  Thus it might make more sense to go with something slightly bigger (SM +12) with a little more anti-capital firepower, better speed and better support for its light cannons... and then you have a cruiser!

On the other hand, a destroyer-type vehicle could serve more purposes than a frigate could, and would definitely be cheaper than cruiser.  The torpedo-corvette is an example of an extreme anti-capital focused ship.  It might be better defeated by a corvette because the torpedo corvette isn't built to handle corvettes.  On the other hand, a destroyer escorting some torpedo corvettes is going to make mincemeat of anti-corvette corvettes and has a decent chance of fighting off other torpedo corvettes.  It's also able to carry more people on it and better equipment (radar and such) and thus has additional flexibility.

In principle, I find that capital ships are excellent generalists: they get a lot of stuff for free with their sheer size, like additional accommodations for soldiers or spare technicians and gunners, long-duration fusion reactors, excellent armor, etc.  They're good at commanding an area and supporting other ships on a variety of missions.  Corvettes really require a level of specialization to be good at what they do: a generalist is too lightly armored, too slow, and too low in endurance to really be effective.  The torpedo corvette is really just engines strapped to heavy torpedo tubes with enough guys to handle it, and some PD cannons just in case.  It borders on "heavy bomber," and its extreme specialization if what makes it look so good against the destroyer: there's no wasted money here, which makes it highly vulnerable to another craft.

Of course, I haven't built enough corvettes to be sure of that yet, but one of my goals of the torpedo corvette was to get a sense of how competitive corvettes were in regards to fighters and capital ships, as Patron Nemoricus in particular worried that corvettes would be "the worst of both worlds," but we can clearly see that a well-specialized corvette is a pretty good craft.  I can see fleets (especially pirate fleets) that focus on corvettes: they're cheap, disposable, and good at what they do.  Are they better than fighters and bombers?  Maybe not, but they're not really worse either, just a different set of tactics.

Assumption Summary

Some of my readers have requested a summary of my assumptions to know how to build something like this themselves.
I've focused this on the Action chase rules and rebuilt the spaceships to operate on more terrestrial scales while pretending to be in space.  In principle, though, I think a lot of these assumptions would work with GURPS Spaceships too, especially if you use all the suggestsions from Planet Hopping with the 23rd Fleet.  I've also built the scale of spaceships against my chosen weapons, so the amount of armor should not be so much thata ship is invincible, nor so little that it's one-shot even with a conditional injury.
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