[Spaceships] A reevaluation of missiles and point defense

[Ulzgoroth]

Ah. It sounds like you're not using the errata which greatly reduce ballistic damage.

[Diomedes]

Originally Posted by SuedodeuS

Maybe I'm not calculating damage correctly, then.

In addition to the revised relative velocity table, you're transitioning between Damage and dDamage; that's throwing your calculations off. A 2cm warhead does 3d dDamage, for 10.5 points on average. Multiply that by 10 for velocity and you get 105, which even a single layer of non-hardened diamondoid can absorb at SM+15. The max damage would be 180, which a single layer of armor can still take.

[joelbf]

Originally Posted by SuedodeuS

Maybe I'm not calculating damage correctly, then. According to pp. 59-61, ballistic weapons gain damage based on velocity. At standard scale and 3-minute turns, relative velocity is 10 mps, meaning damage would be multiplied by 10. Thus, the lowly 2cm shell (from an SM+5 VRF medium battery) deals a whopping 1050 damage on average, with an armor divisor of (2).

You are doing it mostly right. Two things:

1) The table on p. 59 has ben erratad. Standard scale 3 minutes is now 1mps. Se here: http://www.sjgames.com/errata/gurps/4e/spaceships.html .

2) 3dx10 (assuming 10 mps) is 105 dDMG on average, easily attainable by a sm+12 ship (2 armours is 140 dDR). Both damage and armour is expressed in D-scale.

[SuedodeuS]

Oh, hey, there's an errata. Yeah, guns aren't nearly as powerful as I thought, then. Nevermind what I said earlier - fighter-scale guns are going to pretty much be useless against capital ships. They might be able to get away with aiming at weak spots in the armor, but they're suffering enough penalties for using guns as it is.

Yes, fighters will have to use missiles to take out anything much bigger than themselves, and it will require a large group of fighters all firing large collections of missiles to do so. Space combat is expensive.

[Ulzgoroth]

Boobis, looking over your original math post, where is the split-fire penalty in that? Dividing your fire 5 ways is supposed to be a -8 to each.

Of course, it's not too clear how you work the split-fire penalty for point defense at all...

[joelbf]

Originally Posted by Ulzgoroth

Boobis, looking over your original math post, where is the split-fire penalty in that? Dividing your fire 5 ways is supposed to be a -8 to each.

Of course, it's not too clear how you work the split-fire penalty for point defense at all...

My impression was that since Wait and Point Defence says you can fire unspent shots at later volleys, and does not mention spread fire penalties, and all other mentions -2 for spread fire explicitly Point Defence does not suffer from spread fire penalties.

[Dinadon]

Originally Posted by SuedodeuS

Well, a proximity warhead does function as a shotgun (and you might be right about them just simplifying the RoF). Point defense is, as mentioned by Boobis, at point blank range - that is, ~100 miles. The warhead explodes when it's basically right on top of the ship (range 0), and that is how it deals its damage. If it detonated 100 miles prematurely, at best a few pieces of scrap are going to reach and hit the target. Although said scrap would be moving at impressive speeds, I doubt it would be able to do any real damage.

Think about a shotgun that fires buckshot at a tree from 1 yard away. Now think about the same shotgun firing buckshot at a tree from 10 miles away.

I would question several things in that analogy. 100 miles in space is more equivalent to 1 yard than 10 miles. A shotgun has a wide spread, but it shouldn't be too hard to have the missile explode in such a manner that the resulting shards stay on target as much as possible. A shotgun also has to deal with air resistance, which is lacking in space combat. So long as the fragments are on target, it doesn't matter too much when the missile splits up.

Anyway, proximity detonation is suppose to overwhelm an opponents defenses. If an opponents PD could shoot down your missiles before they split it defeats the whole point of trying to overwhelm their defenses, thus the best time for the missiles to split is just before they enter PD range. Plus one of the key descriptors of proximity warheads is 'at a distance', exploding right on top of the ship is surely what normal warheads are suppose to do.

[Cernig]

I think people are confusing multiple independently targetable warheads with a "proximity detonation", which is designed to increase the possibility of a hit, albeit a lesser one, on small and agile targets.

In real-life, proximity detonation isn't used to target real warships, but is used against fighters and missiles i.e. the AA and AM roles. Such a warhead, in real life, is just as vulnerable as any other to point defense because it doesn't explode into fragments until very close i.e. within the lethal fragmentation radius of the warhead.

There aren't, IMHO, rules for MITW in Spaceships (and GURPS is lacking on submunitions like cluster-weapons, mine dispensers and skeet EFP's generally) - although there should be. Likewise there's no provision for home-on-jam or skip-to-track missiles or onboard ECM/ECCM for missiles. Conceivably, the Spaceships rules could be scaled down to provide such.

Regards, C

[joelbf]

The more I think of proximity detonations the more I think something isn't right.

I would love to get my hands on ammo that would split up in 25 independent warheads/impactors (that's whats needed for +4) and still retain the original energy for each and every fragment. Only thing is loss of AP and that I believe is attributed to deformation.

So Proximity Detonation is a darn good deal in any case.

Now to be able to hit with more (up to x10) projectiles than were launched, this is just magic. Bullet damage in GURPS is if I get it right mostly a function of penetration, which is mostly a function of kinetic energy. To be able to hit with 10 times what were launched means a good deal of energy is added to the projectiles (from nowhere I figure). This strikes me as an error, probably from some earlier draft where Proximity Detonations might have done less damage like a shotgun does with shotshell instead of with slugs.

In my games I'm going to skip the x10 rule outright, and I'm thinking of reporting it as errata.

[Dinadon]

Originally Posted by Boobis

To be able to hit with 10 times what were launched means a good deal of energy is added to the projectiles (from nowhere I figure). This strikes me as an error, probably from some earlier draft where Proximity Detonations might have done less damage like a shotgun does with shotshell instead of with slugs.

What about the fact the missile explodes to get that many fragments? It doesn't just break up.