[Spaceships] Weird Numbers

[Mailanka]

So, unable to sleep and still tinkering with how combat should work in my space opera, I dig out a spreadsheet, GURPS Spaceships, and start working out some math. It bugged me that while there was an article for the square root of destruction (making beam weapons more powerful) there was no comparable one for tuning down the damage of guns (the cube root of destruction).

Some things that popped out at me: The base beam damage is the cube root of the battery size x1. It's pretty much straight across the board.

The HP of every ship is inflated. Not by much, but Pulver has generously rounded up in each case.

Finally, ballistic damage has nothing to do with the square root of anything. It's the bore size (in cm) x 5. Look for yourself: 2cm guns deal 3d damage. That's an average of 10 damage, or 5x2. 10cm guns deal 3dx5. That's an average of 50 damage, or 5x10. 112cm guns deal 6dx28, that's 560, or 112x5 (note that this is using the GURPS formula or "2d = 7, 3d=10" rather than 1d = 3.5)

I imagine this is because these guns are HIGHLY abstracted, moreso than beam weapons. We have tonnage translating into bore size, which makes no real sense. There's no particular reason that a 1.5 ton gun HAS to be 10cm in bore size. In fact, that actually doesn't work with EM guns, which tend to have much smaller bore sizes with similar weights. Furthermore, boresize only has so much impact on damage: A 10mm rifle does more damage than a 10mm pistol, because it has a longer barrel and likely more charge behind the bullet. Thus, rather than letting us fuss with barrel lengths, the type of bullet and the bore size, we just get "Look, a 1.5 ton gun is 10cm and does 50 damage on a d-scale, approximately.

This has an interesting side-effect. If you find guns are doing far too much damage, you might be playing with small ships. Even before we get into relative velocities, a 1.5 ton gun fits on a 30 ton ship (SM +5). It deals about 50 damage, and the ship only has 20 HP. Even with three layers of exotic laminate, some of that damage is going to get through (especially with an armor divisor of 2).

But a 150,000 ton gun with a 56cm barrel on a SM +15 ship deals 280 damage while the ship has 1,000 hit points. A single layer of nanocomposite will stop this dead without an armor divisor, and two will stop it with even with an armor divisor of 2, never mind exotic laminate.

Even when you account for relative velocities, as you scale ships up, ballistics becomes less and less important.

Beam weapons don't have this problem. They scale with the ship, and deal just slightly under 1x HP per shot. Thus, an SM+15 beam cannon, or an SM+20, or SM+100 beam cannon does the same proportional damage to a ship of the same size, always.

[vierasmarius]

I've considered addressing this by using a scale for projectile damage that parallels beam damage. Basically, just decide on how much damage a gun should deal relative to an equal-sized beam, and multiply the beam damage accordingly. My (non-playtested, W-A-G) values for this were x1.5 damage for guns, x3 for missiles. An SM+9 Major Battery beam weapon deals a base of 4dx5, so an equal-sized cannon deals 6dx5, and a missile 6dx10. This does have the side effect that equal-caliber guns and missiles don't have the same base damage; a 20cm cannon is an SM+9 Major Battery, for 6dx5, while a 20cm missile is SM+5, for 6dx2. I think that's fine for Space Opera, and could be handwaved by projectiles being faster moving than missiles (not realistic, but matches the WWII-feel of fighters).

[Mailanka]

Originally Posted by vierasmarius

I've considered addressing this by using a scale for projectile damage that parallels beam damage. Basically, just decide on how much damage a gun should deal relative to an equal-sized beam, and multiply the beam damage accordingly. My (non-playtested, W-A-G) values for this were x1.5 damage for guns, x3 for missiles. An SM+9 Major Battery beam weapon deals a base of 4dx5, so an equal-sized cannon deals 6dx5, and a missile 6dx10. This does have the side effect that equal-caliber guns and missiles don't have the same base damage; a 20cm cannon is an SM+9 Major Battery, for 6dx5, while a 20cm missile is SM+5, for 6dx2. I think that's fine for Space Opera, and could be handwaved by projectiles being faster moving than missiles (not realistic, but matches the WWII-feel of fighters).

Something has to change, I think. Otherwise, you get the same weirdness with ST and Super-ST, where one is clearly superior to the other at a certain scale. At very high SMs, missiles and bullets become useless, and at very small SMs, beams become useless. Your solution at least allows both to remain equally valid through all scales.

[Lamech]

Originally Posted by Mailanka

Something has to change, I think. Otherwise, you get the same weirdness with ST and Super-ST, where one is clearly superior to the other at a certain scale. At very high SMs, missiles and bullets become useless, and at very small SMs, beams become useless. Your solution at least allows both to remain equally valid through all scales.

The solution for spaceships is actually when you get to a higher scale you start launching missiles that are modeled as "spaceships". Consider the following ship
TL 9 Missile

Front Section
Armor*4
Fuel Tank*2
Middle section
Armor*4
Fuel Tank*3
Rear Section
Armor*2
HEDM Rocket*2
Fuel Tank*2
Control Room (run by AI)

Then proceed to ram the target. Every 20 second turn the ship gets .5 mps, with 4mps of fuel total. (Plus arguably if you ram a ship you count as "docked" with it for the purposes of explosion damage.) Even a tiny 5 SM missile could hit for 1000ish HP. You could also consider a bit of point defense, or other kind of launcher in the front section for extra fun.

[Mailanka]

For my smaller scale, I've been toying with just taking the weapons from UT and T&T2 and slapping them onto ships. I know their weights, so it isn't hard to find what size ship they would fit on, and you just drop a zero from the damage to find out how much damage they'd do in spaceship scale combat.

This has two benefits. The first is that the weapons scale exactly with ground weapons (as they ARE ground weapons), which suits my campaign just fine. Secondly, the weapons in T&T2 scale their damage up by a cube root, rather than a square root. The cruise missile, for example, with a HEMP round attached does about 100 d-scale damage (armor divisor 10), and if we extrapolate an HSML for a cruise missile, we find it's about a major battery for am SM+9 vessel, which has about 100 d-scale hitpoints, which is a highly satisfying result.