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Old 05-26-2022, 08:46 AM   #1
Join Date: Sep 2011
Default Comparison of Space Beam Weapons in GURPS Vehicles, 2 Ed.

Recently, I started doing some conversions of FGU’s Space Opera to GURPS, specifically Starships of War, Vol. 1. If you haven’t bought the book, there are some potential problems with using it as written. All star nations in the game (so far, volume one covers four of the star nations and there are at least nine other star nations that have been mentioned) use Nova guns (pulsars in GURPS Ultratech; antiparticle beams in GURPS Vehicles, 2nd Ed.) and MegaBolts and StarTorps (which have ratings that translate into Nova fire for damage). The only differences in armament is the calibre used (which affects damage and range) and the number of weapons mounted. The issue with that is that the author had some blatant bias towards the starnations. On any given class of ship, the Terran Union has more weapons and bigger caliber weapons than any of its opponents, followed by the Azuriarch Imperium, Merchantile League and finally, the Galactic Peoples’ Republic. Additionally, some classes of starship don’t appear in some of the star nations’ inventories.

Thus, I was left with a need to do a major revision of the starships. I don’t necessarily intend to eliminate bias in ship design, just substitute my biases for those of the author and, I hope, make my biases a bit more subtle. But before I can do a proper job of introducing my biases, I need to know the objective properties that I’m dealing with, hence this thread. I haven’t seen a thread that deals with the differences in beam weapons for GURPS. That doesn’t mean one doesn’t exist, just that I haven’t found it.

Basic Considerations

FGU’s Space Opera arranges the armament of warships into as many as four batteries (where a battery consists of all the guns in all the turrets that have the same calibre) named: Main; A; B; and C, in descending order of calibre size. The calibre of a NovaGun is identical to the damage it does, i.e. a N*1000 NovaGun does 1000 points of damage. Given the supposed destructiveness of Nova fire, and that the NovaGun calibre increase in steps of 25, I decided on a conversion of N*25 = 1 FP in GURPS. After playing around with various sizes of anti-particle beam weapons, I decided to use different types of beam weapons in the different batteries.

In choosing the armaments for the different batteries, I had to decide what the priorities for my choices would be. First, no weapon that couldn’t be used in vacuum would be chosen; screamers and stunners were gone and any weapon that was completely outclassed by another weapon went as well, so all paralysis beams mounted are military paralysis beams. With that out of the way, the first consideration had to be MAX Range. Damage doesn’t matter if I can hit you and you don’t have the range to hit back, you might just as well be unarmed. That said, damage was the next consideration. It’s always nice if I can hurt you worse than you can hurt me. Weight and cost were the final considerations in determining what weapons would be mounted. Ranges are after factoring in the “in vacuum” range modifiers, and are given as kilometers (they’re not really, they’re kiloyards, but it’s close enough [10% longer than real kilometers] and a bit easier to visualize), GURPS Firepower [FP] ratings are used as a measure of damage and empty weights of the weapons are expressed in short tons (2000 lbs.), again for easy visualization.

The following factors were constant across all weapons to keep the comparisons meaningful: cyclic rate (and Rate of Fire) is 1 for all weapons; all weapons have the extreme range option; no weapons have the compact option; all weapons are as they would appear at TL 16 (so FP, Cost, and Max range are fully comparable). This does mean that those weapons that can, are benefiting from being perfected at earlier TLs in terms of FP, Max range and Cost.

There is one other oddity of note in my comparison, weapons are not being compared on the basis of having equal Beam Outputs. Instead, they are based on all requiring the same amount of Power from the powerplant (or energy banks), on the basis that the ship designers don’t want to redesign the entire ship around the weapon. They might, but for comparison purposes, the weapon designers all have to use the assigned powerplant. The Powerplant has the very odd numbered rating of 23,136,140 kJ. Minor exceptions have been made for three weapons as trivial differences for the math involved: grasers and military paralysis beams draw 1 kJ more; and fusion beams draw 2 kJ less than the standard Powerplant rating. The Powerplant rating was chosen because it is the lowest rating that ekes out FP 1 for the weakest weapon in the lot.

The Comparisons

The UV laser is surprisingly good. At 1,061,100 km, it has the longest range of any beam weapon and its FP 31 is decent enough. The rainbow laser is marginally less effective with a range of 1,000,500 km and FP 29. Where the rainbow laser kills the UV laser is in cost and weight. At $22 million rainbow laser costs less than half as much as a $48 million UV laser and weighs only 650 tons instead of 950 tons. Most starship designers are willing to make the tradeoff and mount rainbow lasers instead of UV lasers, but their ships do need heavier armor to get within range of the odd ship that mounts UV lasers.

X-ray lasers and grasers are usually relegated to the A Battery, due to range issues. X-ray lasers have a range of 689,400 km with FP 54 and grasers have a range of 599,700 km with FP 105. The increased damage is usually enough to offset the reduction in range in the minds of most designers. X-ray lasers and grasers both cost $8 million and weigh 250 and 120 tons respectively. By maturity grasers are always chosen over X-ray lasers, but until maturity X-ray lasers are generally competitive.

Disruptors and neutral particle beams have identical ranges, 15,930 km, and identical FP, 101. Disruptors weigh as much as UV lasers, 950 tons, compared to neutral particle beams, which weigh the same as rainbow lasers at 650 tons. However disruptors, like UV lasers, only cost $48 million, while neutral particle beams cost $130 million. Additionally, disruptors and neutral particle beams have the same range in atmosphere (sort of, to operate in atmosphere, the neutral particle beam needs to have the option of operating as a charged particle beam, which it can, but it adds to the cost and weight). The disruptor is usually the superior choice between the two but will be a B battery weapon. The other potential B battery weapons are the antiparticle beam with a range of 14,250 km and FP 224 and the flamer with a range of 12,090 km and FP 79. The disruptor lords it over the flamer but the flamer is occasionally chosen for its reduced weight of 650 tons and cheap price $38 million, while the increased FP of the antiparticle beam is often considered a good tradeoff for the reduced range and it’s extremely light at 75 tons and inexpensive at $28 million.

The remaining beam weapons are all C battery candidates, having “short legs”. The gravity beam has a range of 3,800 km and FP 200; the disintegrator has a range of 1,900 km and FP 1400; the military paralysis beam has a range of 690 km and FP 82; the fusion beam has a range of 600 km and FP 119; and, finally, there is the displacer with a range of 16 km and FP 1. As for the other statistics: a gravity beam weighs 130 tons and costs $9 million; a disintegrator weighs 105 tons and costs $37 million; the military paralysis beam weighs 195 tons and costs $10 million; the fusion beam weighs 21.5 tons and costs $6 million; and the displacer weighs 3.5 tons and costs $2.9 million. In general, the gravity beam is a good buy and has the best range; disintegrators are preferred by nations with deep pockets who usually consider the vastly increased damage a more than fair trade-off for the increased damage; fusion beams appeal to designers looking for cheap weapons that don’t weigh much; military paralysis beams are generally chosen only by star nations with a philosophical bent for “humane” warfare; displacers are usually a “they stink for range and have pitiful damage, but they’re cheap and don’t take up much room, so we’ll throw in one or two, just for good measure” weapon choice.

Last edited by Curmudgeon; 05-26-2022 at 09:14 AM.
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beam weapons, comparisons, space, vehicles

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