Damage-wise, I'd start with 1/6th the damage of the next smaller size warhead. That should account for the mass of the focusing mechanism and efficiency losses.
But hard to scale. The best missile is an Attack Value of 4, which means that a Killer Whale explosive/laser core (or laser-head as the Honorverse calls it) would be 0.5. Congratulations, you have a 100 ton missile that hits as hard as a medium laser. This would be a lousy return on investment without something else to encourage taking it. With such a return, it would likely have never made it to deployment past an attack against the research facility.
Now, if the weapon fired a cluster of such lasers that could hit the target, each with a Medium Laser power, then it would be a possibility. It would effectively turn the missile into a form of LRM. This was what I was referring to as a Cluster in the initial post. I was considering this as a future development when an effective laser-head for the Barracuda, so that the Killer Whale would use like 3-4 Barracuda cores to do the job.
One way to deal with the to-hit issue is to make it two rolls: one to get the missile where it needs to be, and the other to actually point in the right direction. I don't think either one needs a penalty. Making two rolls will sufficiently lower the odds to match the difficulty of pulling off this trick.
That could work, but add even more work to it. In a way, we may as well use the 2 Cluster Table and require an end result of 2 in order to work. And yeah, that would lower the possibilities of a hit, but would such a lousy chance of connection make it worth while to field for any level of production?
As far as point defense interaction, there shouldn't be any, as the whole point of this is avoid point defenses. If for some reason the missile crosses another ship's point defense bubble, the interaction should be as normal. If the missile isn't reduced to 0 damage (i.e., destroyed) you could apply a penalty to the second to hit roll above to represent the damage.
Part of it is a question of balance.
Fluff-wise, the lenses are have to be high enough in quality to do damage, but low quality enough to justify in a one-shot payload. That means the lens would be large, but the focus would make it less-effective over a rather short range. It would still be outside of full contact range, but close enough to be affected by AMS if it caught it in time. So the engagement envelope against it is possible, but much shorter than normal contact heads.
The whole point of a bomb-pumped laser would be that it would fire from outside PD range of the target. Being (in theory) a collimated beam of X-rays, the trick is aiming it correctly, and (marginally importantly) realising it's a two-way beam.
(Side excursion into X-laser theory. Lasers rely on reflecting energy in a medium, building up excited atoms until they all 'dump' in synch. A small hole in one of the end mirrors lets the beam escape. Now what reflects X-rays? The proposed solution involved using a nuc to 'pump' long carbon rods, relying on interactions within the long rod act as inefficient mirrors, but with the power of the atom behind it. End result was in theory beams of X-rays emerging along the carbon rod's axis. In theory, one nuc could easily 'pump' multiple rods, which could potentially be aimed in all directions. Argus, Hedgehog, Sea Urchin, take your pick.
Of course, it never worked in our reality, but in the Future of the 1980s ... )
Depending on materials involved, the X-rays would either dump some of their energy on the target's skin, causing thermal effects (local vaporisation) which would throw incoming warheads off course. Penetrating X-rays would scramble electronics, cook internal components, & generally do Bad ThingsTM.
True, but it doesn't have to be an x-ray laser. Yes, both the Honorverse and Project Excalibur were both targeting that result with their concepts, but that doesn't necessarily mean that would be the method that a 32nd Century scientist who had access to non-x-ray combat-ready lasers would use, either.
Of course, it doesn't necessarily have to be a bomb-pumped laser, just a missile-delivered one-shot laser (or laser), and that definitely reaches a point where target PD would be pointless, unless, as stated above, the laser was set up more for power or penetration than for range.
When applied to BT, I'd be tempted to play them as
- not interceptable by the target's PD. Of course, they could be intercepted by screen launchers, etc operating at a distance.
- Not having great to-hit chances - BT's computing & sensor power are far more limited than RL's, so aiming at a distance at a maneuvering target won't be simple
- Doing minimal armour damage - after all, X-rays aren't easily blocked
- I would give them a chance for a critical.
After all, if the beam passes through a cargo hold, not much will happen. If it strikes the bridge, the crew now glow in the dark while they twitch out their remaining minutes. Hitting an engine might cause components to fail & overload, while hitting a fuel tank might cause pressure excursions.
Which admittedly pleases the game designer in me - provides a unique weapon with its own foibles & strengths.
It would make it interesting to have a missile designed to decrew a vessel to prepare it for boarding. But wouldn't a neutron weapon (something that was available, and more known to do that, in the 1980s) be more appropriate?
Of course, they tended to be indiscriminate, so a deliberately setup x-ray laser, either as a mount or delivered by fighter or missile would be interesting. But also, aren't x-rays blocked by the same heavy metals one would design in to a spaceship to block general cosmic radiation?
