Kenneth Witt:
Using Bay Weapons as Spinal Guns
The GURPS Traveller Starship design rules suggest that warships too small to use a conventional spinal mount weapon may use a bay weapon in a fixed mount as a scaled down spinal weapon. There is only one major difference between a bay mount and a fixed spinal weapon and that is, of course, the mount. A bay weapon always has either a full rotation universal (external) or a limited rotation casemate (internal) mounting to allow the weapon to rotate or elevate to track targets independent of the attitude of the ship. The mount (either universal or casemate) masses half as much as the base weapon and displaces one cubic foot per 50 lbs. A spinal weapon has no mounting of any type. It is welded to the frame of the starship and forms the ship's major fore to aft structural element. The only way to track a target with a spinal mount weapon is to point the nose of the ship at the target. So, to convert a bay weapon for use as a spinal mount, you need only subtract off the mass, volume, and cost the 'Mount'. That is where the table below comes in. It shows revised values for the standard bay mount energy weapons redesigned as spinal mount weapon systems. These small spinal mount guns are suitable for use on warships with displacements of around 1,000 to 2,000 dTons. Note that all these weapon systems include a dedicated hardened mainframe computer of complexity: Tech Level minus three. The dedicated fire control computer provides a targeting bonus of Tech Level minus two for the weapon.
Weapon Description | TL | Compact | Volume | Mass | Cost | Power (MW) |
Sm Particle Beam/ 9 7.4 GJ | 9 | No | 44 | 293.5 | 68.04 | 246.7 |
Sm Particle Beam/10 12.8 GJ | 10 | No | 34 | 336.8 | 23.13 | 427.0 |
Sm Particle Beam/11 23.3 GJ | 11 | Yes | 41 | 345.5 | 57.50 | 776.7 |
Lg Particle Beam/ 9 14.9 GJ | 9 | No | 88 | 590.8 | 136.88 | 496.7 |
Lg Particle Beam/10 28.5 GJ | 10 | No | 76 | 749.2 | 51.40 | 950.0 |
Lg Particle Beam/11 46.7 GJ | 11 | Yes | 81 | 692.4 | 115.18 | 1556.7 |
Sm Meson Beam/12 12.8 GJ | 12 | No | 34 | 336.6 | 20.95 | 427.0 |
Sm Meson Beam/13 23.3 GJ | 13 | Yes | 41 | 345.2 | 56.67 | 776.7 |
Lg Meson Beam/12 23.3 GJ | 12 | No | 76 | 748.6 | 46.54 | 950.0 |
Lg Meson Beam/13 46.7 GJ | 13 | Yes | 81 | 691.9 | 113.51 | 1556.7 |
Weapon Description | TL | ROF | Damage | Half Range | Max. Range | Acc |
Sm Particle Beam/ 9 7.4 GJ | 9 | 1/60 | 4d x 1,000 | 10,201 / 1 | 30,603 / 3 | 32 |
Sm Particle Beam/10 12.8 GJ | 10 | 1/60 | 6d * 1,000 | 14,642 / 1 | 43,925 / 4 | 33 |
Sm Particle Beam/11 23.3 GJ | 11 | 1/60 | 8d * 1,000 | 21,392 / 2 | 64,177 / 6 | 34 |
Lg Particle Beam/ 9 14.9 GJ | 9 | 1/60 | 5d * 1,000 | 14,475 / 1 | 43,426 / 4 | 33 |
Lg Particle Beam/10 28.5 GJ | 10 | 1/60 | 8d * 1,000 | 21,839 / 2 | 65,518 / 7 | 34 |
Lg Particle Beam/11 46.7 GJ | 11 | 1/60 | 5d * 2,100 | 30,286 / 3 | 90,858 / 9 | 35 |
Sm Meson Beam/12 12.8 GJ | 12 | 1/60 | 6d * 1,000 | 14,642 / 1 | 43,925 / 4 | 33 |
Sm Meson Beam/13 23.3 GJ | 13 | 1/60 | 8d * 1,000 | 21,392 / 2 | 64,177 / 6 | 34 |
Lg Meson Beam/12 23.3 GJ | 12 | 1/60 | 8d * 1,000 | 21,839 / 2 | 65,518 / 7 | 34 |
Lg Meson Beam/13 46.7 GJ | 13 | 1/60 | 5d * 2,100 | 30,286 / 3 | 90,858 / 9 | 35 |
Fixed Weapons on Fighters and other Small Craft
Small craft, such as fighters can also make use of fixed weaponry, but the volume of the much smaller weapons (typically lasers) used by fighters will change by only a fraction of a displacement ton when the mount is removed. However customized fixed lasers with no mounts can be designed for this application. By holding the volume constant and using the space that is occupied by the mount in a conventional design, each type of fixed mount laser may be made marginally more powerful than a weapon designed for a turret. Each laser on the following table includes the base weapon with full stabilization, the required fusion power slice plus long term access space, and a rechargeable power cell. Unlike the larger spinal mounts above, no provision for a dedicated computer or gunner is included in the design. When a fighter is built around one of the weapons in the table below, the gun must be operated by a pilot or gunner manning a crew station on the bridge (cockpit) of the fighter and the Targeting program needs to be run on the ships computer.
Weapon Description | TL | Compact | Volume | Mass | Cost | Power (MW) |
Fixed X-Ray Laser/10 360 MJ | 10 | No | 1 | 8.95 | 1.20 | 16.0 |
Fixed X-Ray Laser/10 1,000 MJ | 10 | No | 3 | 24.86 | 2.70 | 44.3 |
Fixed X-Ray Laser/10 1,800 MJ | 10 | No | 5 | 44.74 | 4.86 | 79.8 |
Fixed X-Ray Laser/11 490 MJ | 11 | Yes | 1 | 7.19 | 1.44 | 21.7 |
Fixed X-Ray Laser/11 1,600 MJ | 11 | Yes | 3 | 23.17 | 4.58 | 70.0 |
Fixed X-Ray Laser/11 2,600 MJ | 11 | Yes | 5 | 38.13 | 7.52 | 115.3 |
Fixed X-Ray Laser/12 510 MJ | 12 | Yes | 1 | 7.48 | .85 | 22.6 |
Fixed X-Ray Laser/12 1,500 MJ | 12 | Yes | 3 | 21.99 | 2.49 | 66.5 |
Fixed X-Ray Laser/12 2,600 MJ | 12 | Yes | 5 | 38.11 | 4.30 | 115.3 |
Fixed X-Ray Laser/13 505 MJ | 13 | Yes | 1 | 7.40 | .85 | 22.4 |
Fixed X-Ray Laser/13 1,600 MJ | 13 | Yes | 3 | 23.00 | 2.6 | 69.6 |
Fixed X-Ray Laser/13 2,600 MJ | 13 | Yes | 5 | 38.10 | 4.30 | 115.3 |
Weapon Description | TL | ROF | Damage | Half Range | Max. Range | Acc |
Fixed X-Ray Laser/10 360 MJ | 10 | 1/60 | 5dx60(2) | 20,455 / 2 | 61,364 / 6 | 32 |
Fixed X-Ray Laser/10 1,000 MJ | 10 | 1/60 | 5dx100(2) | 34,091 / 3 | 102,273 / 10 | 33 |
Fixed X-Ray Laser/10 1,800 MJ | 10 | 1/60 | 6dx100(2) | 45,738 / 5 | 137,213 / 14 | 34 |
Fixed X-Ray Laser/11 490 MJ | 11 | 1/60 | 5dx90(2) | 26,250 / 3 | 78,750 / 8 | 33 |
Fixed X-Ray Laser/11 1,600 MJ | 11 | 1/60 | 5dx150(2) | 47,137 / 5 | 141,410 / 14 | 34 |
Fixed X-Ray Laser/11 2,600 MJ | 11 | 1/60 | 4dx220(2) | 60,467 / 6 | 181,401 / 18 | 35 |
Fixed X-Ray Laser/12 510 MJ | 12 | 1/60 | 4dx140(2) | 29,215 / 3 | 87,645 / 9 | 33 |
Fixed X-Ray Laser/12 1,500 MJ | 12 | 1/60 | 6dx150(2) | 50,103 / 5 | 150,310 / 15 | 34 |
Fixed X-Ray Laser/12 2,600 MJ | 12 | 1/60 | 6dx180(2) | 65,964 / 7 | 197,892 / 20 | 35 |
Fixed X-Ray Laser/13 505 MJ | 13 | 1/60 | 6dx110(2) | 31,494 / 3 | 94,482 / 9 | 33 |
Fixed X-Ray Laser/13 1,600 MJ | 13 | 1/60 | 6dx180(2) | 55,531 / 6 | 166,592 / 17 | 34 |
Fixed X-Ray Laser/13 2,600 MJ | 13 | 1/60 | 4dx320(2) | 71,461 / 7 | 214,383 / 21 | 35 |