i think that in addition to this, the railgun\'s power requirement would be drawn from power tanks. if you don\'t have the power storage to fire for max damage of the railgun, you don\'t get all the damage from it
ex: 200m long railgun with 2m gap. max damage requires 5000*length*gap^3 (cubic projectile) and as such would be 8,000,000 energy storage for max damage in 1 shot. if you only have 4,000,000 energy storage, you only get half peak damage, 2,000,000, a quarter of max damage.
damage wise, i think that that total tamage possible from a single railgun shot is all penetrative damage, and is equal to 1/2 the amount of energy required for max damage. so in the above example, this gun would require 8,000,000 energy to produce a single 4,000,000 damage shot that has penetration
AOE characteristics of radius 2m(gap is 2m) from center of the shot is what i\'d say, and the damage amount for the aoe would be 1/distance^2 so damage applicable to the blocks 1m away from the first impact would be 2,000,000, 2m away and the applicable damage would be 1,000,000.
penetrative damage would be calculated by subtracting shield health that would have to be breached first, then the HP of each block destroyed.
at 1 block penetration against hardened hull, with an AOE raidus of 2m, the total damage subtracted from the initial damage would be 400x21xN(some variable here to make railguns more or less effective depending on value. higher for less effective railguns) blocks (8,400 damage times N) (a circle of damage centerd on 1 block on a flat surface with a radius of 2 touches 21 blocks)