TL4 to TL5 Cannons and Carronades

[Anthony]

Originally Posted by Varyon

According to the July 30, 2013 version of Doug's spreadsheet, base penetration damage is ((K^1.04)/(X^0.314))/13.3926, with K as kinetic energy in Joules and X as cross-section of the bullet in square meters. So, it's roughly kinetic energy divided by the cube root of cross section.

Actually, just found it, it's ROUND(SQRT((K12^1.04)/(I17^0.314))/13.3926,1); K12 is KE and I17 is cross-section. If we clean up all the math, we wind up with KE^0.52 * (pi/4*B^2)^-0.157 / 13.3926, or KE^0.52 * B^-0.314 * 0.077554 (KE in J, B in meters, penetration in points of DR).

This is the sort of function that comes from applying a curve-fitting tool to a bunch of data points, it's grossly unlikely to have any physical basis. If it disagrees with some other source, I would simply assume that the formula is wrong. Note that there are fairly strong theoretical reasons to assert that, given constant projectile velocity, density, and shape, penetration should be linear in projectile diameter, and Doug's formula puts the exponent at 1.246 (however, many historical formulas are not precisely linear).