Ran into an interesting dilemma while fiddling with High Guard weapons rules. It boils down to this: the big ship universe doesn't work, at least not for naval combat.
We know the problem with mesons, that's not new. The problem is nukes. I've suggested before that the basic canon turret-launched nuclear missile is equivalent to the old Davy Crockett nuclear warhead, which was a 10.75-inch diameter, ~15.7 inch long, 23 kg (depending on source) warhead with a 10.75" diameter spherical implosion device that (again, depending on source) gave from 0.006 to 0.010 kt - 6 to 10 tons TNT equivalent. Reason is simple: that's the size of contemporary nuke that does the kind of damage a High Guard nuke does. 0.005 kt in Striker produces a 76 penetration, while the 0.01 puts out 82. However, the Davy Crockett was made intentionally inefficient to reduce blast to something that could be fired from an artillery piece without putting the gun crew at risk. A fully optimized warhead of that size could reach 1 kt for the same amount of plutonium, and something 100 times more powerful is going to come away with penetration values in the 90's, possibly 100 or more. At those values, armor is pretty much irrelevant: even a fully armored buffered planetoid is going to get a crater several meters deep blown into it. It's a bit hard to argue a space force wouldn't optimize their warheads when confronted with heavily armored targets. Others, arguing from the Black Globe rules, have suggested the warhead might be even larger. This of course assumes an impact detonation, but there's no reason to assume otherwise if the HE missiles are successfully impacting with the same odds.
Missiles at that point become about as deadly as a meson spinal. For a Factor 9 missile salvo, about 1 salvo in 6 will penetrate a Factor 9 nuclear damper, and agility is not a lot of help to battleship-size targets. The game becomes about being small, agile, and numerous, the new "battleship" becomes something about the size of a destroyer, and fighters become very nasty indeed until the dampers become too big a factor and the computers become too advanced to be cost-effective for them. You end up with a "small ship" navy, with larger ships relegated to support roles where they're less likely to face attack by nuclear missiles.
Traveller dials down the nuke quite a bit in order to be able to offer big ships. Dialing them back up makes an interesting rationale for running a small ship universe.
You could "dial-a-yield" the missile, making it useful for either space combat or planetary bombardment. A very low yield nuke is better for a orbital bombardment missile because, coming down from above, it will kill most armored vehicles on impact, as well as incapacitating or killing most exposed ground troops within a football field's length or two of the target unless they're in TL 14+ combat armor or better, without as much wasted force as a larger nuke. Most grav MBTs and APCs would be designed to survive indirect nuclear attack as long as they're at least in the outer half of the primary radius and would maintain enough spacing that only 1 or 2 would be caught in the lethal inner half of any one attack, so a bigger boom does not usually accomplish much on the ground beyond civilian casualties and ravaged terrain. However, one does prefer to have adequate punch for space combat.
We know the problem with mesons, that's not new. The problem is nukes. I've suggested before that the basic canon turret-launched nuclear missile is equivalent to the old Davy Crockett nuclear warhead, which was a 10.75-inch diameter, ~15.7 inch long, 23 kg (depending on source) warhead with a 10.75" diameter spherical implosion device that (again, depending on source) gave from 0.006 to 0.010 kt - 6 to 10 tons TNT equivalent. Reason is simple: that's the size of contemporary nuke that does the kind of damage a High Guard nuke does. 0.005 kt in Striker produces a 76 penetration, while the 0.01 puts out 82. However, the Davy Crockett was made intentionally inefficient to reduce blast to something that could be fired from an artillery piece without putting the gun crew at risk. A fully optimized warhead of that size could reach 1 kt for the same amount of plutonium, and something 100 times more powerful is going to come away with penetration values in the 90's, possibly 100 or more. At those values, armor is pretty much irrelevant: even a fully armored buffered planetoid is going to get a crater several meters deep blown into it. It's a bit hard to argue a space force wouldn't optimize their warheads when confronted with heavily armored targets. Others, arguing from the Black Globe rules, have suggested the warhead might be even larger. This of course assumes an impact detonation, but there's no reason to assume otherwise if the HE missiles are successfully impacting with the same odds.
Missiles at that point become about as deadly as a meson spinal. For a Factor 9 missile salvo, about 1 salvo in 6 will penetrate a Factor 9 nuclear damper, and agility is not a lot of help to battleship-size targets. The game becomes about being small, agile, and numerous, the new "battleship" becomes something about the size of a destroyer, and fighters become very nasty indeed until the dampers become too big a factor and the computers become too advanced to be cost-effective for them. You end up with a "small ship" navy, with larger ships relegated to support roles where they're less likely to face attack by nuclear missiles.
Traveller dials down the nuke quite a bit in order to be able to offer big ships. Dialing them back up makes an interesting rationale for running a small ship universe.
You could "dial-a-yield" the missile, making it useful for either space combat or planetary bombardment. A very low yield nuke is better for a orbital bombardment missile because, coming down from above, it will kill most armored vehicles on impact, as well as incapacitating or killing most exposed ground troops within a football field's length or two of the target unless they're in TL 14+ combat armor or better, without as much wasted force as a larger nuke. Most grav MBTs and APCs would be designed to survive indirect nuclear attack as long as they're at least in the outer half of the primary radius and would maintain enough spacing that only 1 or 2 would be caught in the lethal inner half of any one attack, so a bigger boom does not usually accomplish much on the ground beyond civilian casualties and ravaged terrain. However, one does prefer to have adequate punch for space combat.