Okay, I have some very simple ruby code that tells you how much to adjust cap-HP when you adjust cap.
pp [1,2,4,8,16,32, 64, 128].map{|cap| dps = (1..cap).map{|i| Rational(i, cap) * Rational(1,cap) }.inject(0){|i,j| i+j}; [cap, dps]}
[[1, (1/1)],
[2, (3/4)],
[4, (5/8)],
[8, (9/16)],
[16, (17/32)],
[32, (33/64)],
[64, (65/128)],
[128, (129/256)]]
So, what's happening here?
If you have a starship with a cap of 1, then then it does 100% of its cap DPS until it takes 100% of its cap health (and dies).
If you have a starship with a cap of 2, then a full cap does 100% of its cap dps until it takes 50% of its cap health and the first starship dies. Then the other starship does 50% of cap DPS until a total of 100% cap health is dealt. That works out to 3/4ths as much damage. This assumes perfect focus fire and no overkill effects, because those are super hard to model.
I don't think you want to change the cap DPS, because some other ship might be tanking and their DPS will be at 100% for a while. Instead, I think high cap ships should get an HP bonus (or low cap ships an HP penalty) that preserves their total DPS output under fire.
The above code lets you put in a cap and see what it's theoretical total-damage-under-fire is as a fraction of a ship with a cap of 1. IE, a ship cap of 2 deals 3/4ths as much damage under fire, a cap of 4 deals 5/8ths, etc.
list= [1,2,4,8,16,32, 64, 128].map{|cap| dps = (1..cap).map{|i| Rational(i, cap) * Rational(1,cap) }.inject(0){|i,j| i+j}; [cap, dps]}; list.each_cons(2){|i,j| pp [[i[0],j[0]],(i[1] / j[1]).to_f]}
[[1, 2], 1.3333333333333333]
[[2, 4], 1.2]
[[4, 8], 1.1111111111111112]
[[8, 16], 1.0588235294117647]
[[16, 32], 1.0303030303030303]
[[32, 64], 1.0153846153846153]
[[64, 128], 1.0077519379844961]
This bit of code lets you put in some caps and see, for a change in cap, how much you should increase the cap HP to compensate for the reduced damage under fire. IE, going from a cap of 1 to 2, you should increase cap health by 33%.
It also makes it clear that this really doesn't matter for regular caps; going from 32 to 64 only recommends a 1% increase in cap HP, which probably isn't enough to bother with. For very low caps, the impact is much more noticeable.
Ergo, the perceived fragility of high cap ships is probably more due to the targetting logic prioritizing them because they're easier to kill, or some other factor.
