Spaceships: How Much Damage Should Guns Do?

by Mohamed Baki

Its been noted that kinetic weapons in spaceships are among the most powerful weapons in Gurps, and they contribute greatly to the "Eggshells with Hammers" paradigm worked out by gurps spaceships. When I scaled spaceships down to SM+0, a major battery didt 15 dice of damage, either as a crushing explosion or with a (2) armor divisor. I'd love to have that kind of damage as a SM+0 player, but I'd dread it as a GM, and it kind of breaks my sense of immersion

Here, we're going to figure out what the weapons damage SHOULD BE, in order to play nicely with High Tech and Ultra Tech. We will be comparing damage, weight, and caliber. While range and rate of fire are also important, I will be ignoring these for now, much as I did in last week's look at beam weapons.

Edit: a post covering how to use these numbers for missiles has been published

Spaceship Weapons: How Much Damage Should Beam Weapons Do?

Gurps spaceships is an extremely flexible system that lets us build not only spaceships but a wide variety of vehicles. Unfortunately, it seems to produce "Eggshells with Hammers": Ships able to trivially pierce each other's defenses, with even dedicated defensive designs struggling to survive a single hit. This has often been attributed to scaling problems, but when I built a SM+0 "Tank Bot" all the problems remained: it was an eggshell with a hammer.

In a previous post, I looked at how tough spaceship's armor should be. I hadn't planned on exploring the weapons systems, but a few folks expressed interest, and I decided to dig into the topic.

So if spaceship's weapons are off, how much are they off, and what should they look like? Here we will look at the damage for one of the weapon systems, and compare it to the Ultra-tech book. Spaceships has two types of weapons: beams and projectiles, and it treats them very differently. This post will discuss lasers, but posts on the more difficult topic of kinetic weapons are coming. Beam weapons are the less troublesome of the two attacks, and this post will focus more on comparison than on changes.

Robots as Spaceships: Arms, Legs, and Mecha

concept art by Pascal Blanche

One of the great staples of science fiction is the humanoid machine. These take many forms: mass produced battle droids, sinister machine infiltrators, humorous robot butlers and futuristic telepresence androids are all essentially machines shaped like a human.  Even power suits are ultimately human-shaped machines capable of moving under their own power. Including humanoid robots in our system is critical, not to mention quadrupeds, octopoids, and other organic shapes.  Spaceships will give us most of what we need, but we will need to extrapolate just a little, and make sure the system builds what we need it to.

Robots as Spaceships: Between SM's

Spaceships categorizes craft by their SM, which is a tool that appears in GURPS again and again because its so useful. However, when we get to human-scale objects, we find that each SM cover a huge range. This is just fine for calculating hit penalties and mana costs, but it falls short as the sole number determining something's size. We need a more fine grained system for determining spaceship sizes.

As it turns out, I already built one, when working with sea monster sizes. We want to go smaller than the monster table, and its nice to have the ST built into it (we're using a very different method for determining ST), so we have an adjusted version. We've also added a base cost to each of these size entries, so that we can use relative and base costs easily.

Weight	SM	Strength	Base Cost		Weight	SM	Strength	Base Cost
5 oz	-5	ST 2	$.015		100 lbs	+0	ST 17	$5
8 oz	-5	ST 2	$.025		150 lbs	+0	ST 19	$7.50
12 oz	-5	ST 3	$.035		200 lbs	+0	ST 20	$10
1 lb	-4	ST 4	$.05		300 lbs	+1	ST 23	$15
1.5 lbs	-4	ST 5	$0.075		500 lbs	+1	ST 27	$20
2 lbs	-4	ST 5	$0.10		700 lbs	+1	ST 30	$30
3 lbs	-3	ST 6	$0.15		1000 lbs	+2	ST 36	$50
5 lbs	-3	ST 7	$0.25		1500 lbs	+2	ST 45	$75
7 lbs	-3	ST 7	$0.35		2000 lbs	+2	ST 50	$100
10 lbs	-2	ST 8	$0.50		1.5 tons	+3	ST 56	$150
15 lbs	-2	ST 9	$0.75		2.5 tons	+3	ST 65	$250
20 lbs	-2	ST 10	$1.00		3.5 tons	+3	ST 70	$350
30 lbs	-1	ST 11	$1.50		5 tons	+4	ST 79	$500
50 lbs	-1	ST 14	$2.50		7.5 tons	+4	ST 92	$750
70 lbs	-1	ST 15	$3.50		10 tons	+4	ST 100	$1,000

We'll refer to each of these vehicle sizes by their weight, and generally throw a motive type in the description as well. So our Gunbot is a 200 lb tracked robot.

This set of weights is still pretty rough-grained, but for any weight we choose, there will be a stat line within 20% of it. This happened because we used the size/range table for weights rather than lengths. This spread of numbers works well with Gurps, and has a lot of support.

We can now build a wide variety of robots at these sizes. Of particular interest is the 100 lb to 1000 lb range: there is a big difference between walker that weighs 300 lbs with the human onboard and one that weighs 500 or 700 lbs. Many fictional androids will be made at the 100 lb or smaller mark, and are correspondingly cheaper.

Lets get out there and build all of the robots we can think of! At least in our games. I take no responsibility for any actual robot legions of doom.

Robots as Spaceships: Chassis and Cargo

Chassis. It rhymes with "Grassy". Blame the French.

In a previous post, we decided that rather than making up a bunch of new weapons for our robots to use, we would use the excellent and well play-tested gear lists in high tech to outfit our gunbot and other robots. This seems to be a simple idea, but it requires using both the spaceships systems and the traditional gear system. In fact, we've already done this, when we added the "Custom System" providing the AI to the robot.

We are going to systematize this, and get comfortable with swapping back and forth between the two paradigms.

Robots as Spaceships: Scaling Costs

So far, we've been playing around with a SM+0 robot, and extrapolating all the costs for systems much smaller than the creators of spaceships ever intended. This method works, but we can make this simpler, while doing so gain many more options for robot sizes. Many otherwise similar robots will differ mainly in size and gear tacked on at the end. Rather than buying systems at the size the spaceship will be, we will build the spaceship at an easy to calculate abstract size, and then scale it to the size that we need.

While this is being presented as part of the robots as spaceships series, this is a tool I've been using for a long time when building spaceships. It simplifies table look-ups, and gives us a lot of power and flexibility we can use to build spaceships that aren't exactly on the SM benchmarks.