These are my final attempts at sensible damage curves for missiles. To achieve them uses the equation;

Damage=MIN(MAX(((EXP(-1*(((TS*(MAX(MR/TR,1))^8)-EV^1.2)/1500)))*W),TR^0.8),W)

TS = Target Speed
MR = Missile Explosion Radius
TR = Target Radius
EV = Missile Explosion Velocity
W = Warhead Strength

To achieve the correct "spread" of missiles affecting the "correct" sized targets also required adjustment of the missile explosion velocities as follows

Rockets - 4000
Standards - 2000
Heavies - 1000
Cruise - 500
Torpedoes - 250

I would envisage these values all being AFTER training Target Navigation Prediction to level 5.

Rockets;

Yes, you read that right, no target gets a damage reduction from rockets below a speed of 5000 m/s.

Standards;

The pink line is the sig=25 curve, so webbing an Inty down to less than 500 m/s would increase damage from standards rapidly.

Heavies;

By this graph, all cruisers would more than likely take full damage from heavies...ships of sig 75 or less can evade damage by keeping above 150m/s. The "tails" you can see on the right of the graph are the effect of the minimum damage limit...no ship can take less damage than its (sig radius)^0.8, which works out to 13 points for an 25 sig Interceptor, 167 for a 600 sig Battleship.

Cruise;

Your average cruiser at 150 sig needs to maintain 200+ m/s to take minimum damage. Larger cruisers would need to go faster, smaller ones slower. All Battleships would take full damage from cruise missiles.

Torps;

The cutoff for Torps is sig radius of about 250/275, which would need to maintain a speed of 200+m/s to take minimum damage from Torps.

I think these feel about right now, but it's also shown that if there are any issues with certain missiles, the properties of the missile could be adjusted to make them more or less effective against targets of a given sig radii.