[Spaceships] Building Spaceships weapons with Blaster and Laser design

[Ulzgoroth]

I was thinking about alternative weapons for Spaceships weapon batteries, and realized that the beam weapon design system from Tech and Toys II could be applied. And disassembling bits of GURPS Spaceships is always fun.

So what happens when I try to build TL9 1.5 ton spaceship weapon systems? Your basic SM +5 major battery includes one of these, plus your choice of ‘fixed’ mount or turret plus control station.


The 10 MJ laser:
This weapon is a laser, does 40d, and has 1/2d range of 70 miles. It has RoF 1 and normally fires once every 20 seconds.

The first thing to solve for is the focal array. The focal array range modifier needed is 700 miles/(40^2*40 yards) = 19.25. The largest array in the article (‘extremely large’) gives an 8, so it’s time to extrapolate. The array scaling appears to be that the range modifier equals the cube of the weight modifier, except for the very small and tiny arrays which get significantly better range than that would indicate. The cube root of 19.25 is about 2.7, so that will be our focal array weight factor.

So then what does this thing weigh? Give it a single-shot generator and… (40*1/3)^3*2.7*1 = 6400 pounds. Considering the entire weapon system needs to fit in 3000 pounds, that won’t do at all. Clearly the single-shot generator is way too much gun for the job. My first thought for weight factor would be 0.5, as the inverse to the heavy automatic generator, but that’s still too much. 0.4 would allow the gun at 2560 pounds, the 200 pound gunner allotment, and 240 more pounds for the rest of the turret and control infrastructure. Which is probably not enough, but I’ll leave it there rather than try to estimate the weight of the gun mounting. This heavy gun generator gives RoF 1 and requires 9 to 19 seconds between shots for recharging (the low end of that to allow improved lasers at the same weight), has a G factor of .4. If we let it have a cost factor of 1, the gun will cost 2560*$500*1 = $1,280K Since the entire mounting costs $1.5M, that’s probably good enough.

Obviously, the weapon has a cannon configuration and uses external power rather than power cells, though you can use the system to determine how many power cells it would burn through. Bulk is -10 (would be -76, but bulk is capped by the system), ST is 121M, and LC is predictably 1.

The 1MJ RF laser:
The weapon is a laser, does 20d, and has 1/2d range of 30 miles. It fires 10 shots every 20 seconds, which brings its rate of fire into question. Spaceships description of how weapons are used means a maximum of one attack in four seconds, or 5 attacks in 20. That means that the RF gun could be built on a semi-auto generator and RoF 2. However, the improved RF gun would need RoF 4, so I’d rather use an automatic generator for consistency.

With 20d and 300 mile range we need an array range factor of 33, indicating a weight factor of 3.2. (Spaceships beam range does not go as the square of damage, so smaller beams have larger arrays and larger ones smaller arrays.)

With a light automatic generator, the gun would weigh (20*1/3)^3*3.2*1.25 = 1185 pounds. That seems awfully light compared to the last gun. With a heavy automatic generator it would weigh 1896 pounds, still significantly lighter than the heavy gun. However, automatic generators cost…the light automatic generator version runs $1185K, and the heavy at $1896K costs more than the entire mounting. So it will have to be the light automatic. I’ll give it RoF 10, so it only needs one attack cycle per 20 second round for the basic gun.

My overall design for the weapon would be the 1185 pound gun plus a power pack of 9 E cells storing up to 10 shots. The E cells are not normally swapped out, but rather are recharged at a rate of 1 shot per two seconds (1 shot per second at TL10) by the ship’s power grid for 1 power point. The complete weapon weighs 1545 pounds and costs $1203K. The power cells can in theory be swapped out in 5 seconds each (assuming you don’t find shoving 20-pound power-cells around difficult). Replacing one discharged cell would add 1 shot (2 at TL10), replacing all of them fully reloads the gun. In theory the core weapon is capable of continuous fire at ten shots per second, given a sufficient power system.

The weapon has Bulk -10 (of course) and ST 94, RoF 10, Shots 10, LC 1. The TL10 improved laser has the same stats except for Shots 20 and the higher recharge rate.

The 100 KJ VRF laser:
The weapon is a laser, does 10d, and has 1/2d range of 30 miles. It fires 100 shots every 20 seconds. The max RoF the design system can give is 20, which can produce 100 shots but can’t scale to 200 for the improved VRF. I prefer to build the VRF weapon as a unit of 5 guns with heavy automatic generators, allowing RoF 100.

With 10d and 300 mile range we need an array range factor of 132 (!), indicating a weight factor of 5.1. That’s a high price to pay for range, though perhaps worth it if you’re using this as an anti-fighter gun.

Each RoF 20 unit weighs in at 378 pounds, and the combined mount comes to 1890 pounds and unfortunately costs $1.89M. A 225 pound combination of an F cell, E cell, and D cell stores up to 101 shots and brings the system to 2115 pounds. External power from a ship’s grid refills 5 shots per second. Shots and recharge double at TL10.

The weapon has bulk -10 and ST 110.

Instead of aiming for 100 RoF in a single burst, a single one of the $378K, 378 pound units could be mated to a pack of 9 D cells to make a 423 pound system with RoF 20, shots 20. That would have bulk -10, ST 49. That’s far too light a weapon for a 1.5 ton mount, though.