Re: Is spaceship armor useless?
 

That's not about GURPS Spaceships in particular so much as it is simulation as opposed to heroic narrative. You could make the missile run into a heroic narrative by picking out the heroes, and assuming that everyone else's missiles will accomplish nothing except to tie up a share of the point defense, so it's all up to the heroes...and maybe give them some kind of 'deceptive shot' option so they can leverage awesomeness to get hits through better.

(Forcing the bombers to run a gauntlet through a dogfight before launching, well, there you do have a Spaceships-related problem where flying through the weapon envelope of the fighters is going to be too long for you to just endure.)

Re: Is spaceship armor useless?
 

Yeah GURPS spaceships lends itself to battles which you don't see in fiction. Shields are taken down by spraying them with thousands of shots. Missiles are a kill if they get through point defense, but useless if they don't. (And generally PD wins.) Nukes are excellent point defense weapons, but suffer the same problem as above. Armor is penetrated with high power beams.

But it does lead to a good number of strategies. And ships which are effectively Disco Balls of Doom.

Re: Is spaceship armor useless?
 

I do not think this is correct unless the user of the missiles is doing it very wrong.

Re: Is spaceship armor useless?
 

It's probably more accurate to say that whoever can saturate the void with more pewpewpew wins, as skill levels tend to be at least somewhat similar. Also, PD can get higher hit probability in the last phases of the missile flight by shooting at shorter and shorter ranges.
And battery construction seems to favour light beams over missiles, since you always take the tiniest beams available as long as you have enough gunners (likely you do if you have AIs of any sort!).

Re: Is spaceship armor useless?
 

Well, that would depend on the exchange rate in 'pewpewpew'. Which given that the defensive weapons are likely VRF will be nowhere remotely near 1:1 unless you use the 'missiles are worthless' variant rule. (Missile Shield, that is.)

I need to grind some numbers PD versus missiles for tactical rules, actually. In final defensive fire, VRF beams are not the equal of fragmenting missiles. But killing all the buses before they get to make their own attack rolls might turn things.
You always take the tiniest missiles available and give each launcher a gunner too, there's no difference there that I can see.

Re: Is spaceship armor useless?
 

It'll still likely end up in one of 'still so much disco that missiles do not reach the target' or 'such a swarm of missiles that disco ball gets dozens of holes nose to tail'. That being said, see below for the ratio of shots fired by different batteries.

Of course, much magic occurs with deciding how to split the RoF into multiple salvoes and what is the speed and the like.

Indeed, the idea is to shoot the missiles while they're still able to manoeuvre but are not as numerous as fragments.
(Also, not all settings seem to have frag missiles, and I think the reason is that some worldbuilders hate them. ^_^ )

The combined firepower favours beams (and, to lesser extent, guns), though:
E.g. for a Medium Battery on an SM+5 ship, you can get either three 16cm launchers (with 5 missiles total) (and I'm not even sure missiles less than 20cm are supposed to be available, I'm rusty), or three 8cm guns (with 50 shots total), or 3 3MJ beams (infinite ammo, but needing a reactor).
But your beams become VRF, for ×100 RoF, for a +7 to hit.

Of course, much magic occurs with deciding how to split the RoF into multiple salvoes and what is the speed and the like.

Re: Is spaceship armor useless?
 

...well, of course those two states cover most of the space of possibility. The question was always which of those two outcomes is going to happen, not whether either of them will.
What settings have kinetic-kill missiles but no fragmentation?

Lots of settings don't have kinetic-kill missiles, of course. Often found together with lack of point defense and completely unrealistic maneuvering physics. But if you've got no KK missiles you're way, way off the baseline for Spaceships.
16 cm missiles are clearly supported. The only thing in the book suggesting otherwise is the faulty "Guns and Launchers Table".

And that +7 to hit can't be taken on its own. The missile has +(TL-8) for accuracy, +target SM and +4 for proximity fusing. Assuming you're engaging on the last possible 20 second turn, the missile is at -4 or so relative to the beam for range modifier versus speed modifier regardless of what the speed is. The beam takes -1 for the missile's SM. Overall modifier difference...about TL+tSM-14 in favor of the missile. You could credit the beam another +1 for being an Easy skill and +2 for using a fixed mount.

....But I realize that comparison doesn't matter because we, again, are not talking about Wait (Point Defense) but about shooting down the missile before it makes its own attack at all. The missile's attack roll only matters if the beam doesn't kill it first. One for one, the beam will be rolling with a total +6 or better modifier and is almost certain to make the kill. Any missiles that aren't killed will be at a sufficiently large bonus that they ware very unlikely to miss or be dodged (and of course enough damage to ruin the recipient's day).
I am quite certain that the answer for salvos is simply one missile per salvo. I can't think of any downsides at all...

Re: Is spaceship armor useless?
 

I think you're underestimating Beam PD vs. even Prox. Det. missile attacks.
1 missile, Prox. Det., can score 10 'hits'.
PD with a VRF, Imp Laser get x200 RoF (for +8) with even a low AI Skill of 12 and an average roll of 10, that's 10 hits, which kills all of the missile fragments.

Its true that if even one fragment gets through, the target is pretty much toast, so luck will eventually favour the missile, assuming they don't run out of their limited ammo first.

I personally prefer to use the Alternate HP from David Pulver's Extreme Damage article in Pyramid#3/34 - which means larger vessels can soak a few missile hits with their significantly increased HP.

Prox.Det. ballistic attacks lose their armour divisor, but their base damage is unchanged. I find this a little unsatisfactory, splitting the warhead into 10 fragments should reduce the damage too, I've considered adapting the Shotgun rules for Solid Shot vs. Buckshot and dividing the damage of each fragment by 4 (treat as 1/4 calibre), but I've not played that out to see how it works.

Re: Is spaceship armor useless?
 

And which of those two outcomes is going to happen is very much the case of 'whoever has more pewpew, wins'.

That's actually an important consideration:
G:SS seems largely obsessed with KK missiles (nukes come a close second, while conventional explosive missiles are not talked about much, if at all).
IIRC EvE has thermal, kinetic and explosive warheads.
Star Wars seems to have explosive and/or kinetic missiles and thermal/explosive torpedoes, as well as conventional bombs, plus some exotics like droid-dropper missiles.
Star Trek has photon torpedoes at least.
Yes, all of those use weird non-Newtonian drives, but GURPS Spaceships do support non-Newtonian drives (including hyperdynamic ones); and yet its pseudovelocity missiles seem to behave much like KK ones.

Yeah, that was why I started doubting their legitness.

Oh, the just-Attack-them-along-the-way vs. Wait (PD) dances. I need to get my head around those numbers . . .

The -4 per multitasking, mostly. Or the need to have more operators, which, again, is a non-issue with AIs for both sides.
Also, with smaller salvoes, it becomes actually possible to dodge at least some of those that get past the beam screen and/or beam PD, since you no longer need huge MoSes to dodge the whole salvo. Which is of no use if there's a dozen or more (chance to dodge is likely too low to dodge them all), of course.

BTW, something I've seen people consider: using small missiles against enemy missiles; not sure how viable that is.

Re: Is spaceship armor useless?
 

That's not answering the question in the slightest, unless you're saying that it's a one shot to one shot exchange rate, which is obviously not right.
Because, of course, conventional explosives make no sense.
But they're referred to in multiple other tables in Spaceships, and used on designs in Spaceships 3 and 4.
-4 for multitasking how? Launching one missile per turn is simply normal. And I don't see anything saying that resolving a ballistic attack counts as a task. (And I wasn't suggesting stacking up your salvos to hit with them all at the same time, though you obviously could and probably should.)

Anyway, multitasking multiple gunnery tasks is explicitly forbidden in Spaceships 1, so there's no way that penalty could apply.

You need huge MoSes to dodge, since single frag missiles have 10 potential hits at de facto rcl 1, and pretty heavy bonuses.
It could work, but against 1-missile salvos it's not going to compare favorably against beams (which can split fire) for area defense. It might be better for Wait (PD), but I'm not sure about that.