e is Euler's number. It's a constant.
mv are mass and velocity. Kinetic energy equation is 1/2 mass multiplied by velocity squared.
It appears that the square root term becomes dimensionless. The cube root term is raised to the 2/3 of a power (cubed root of a squared dimension). As ac result, I assume d is the damage as a function primarily of the size and mass of the projectile. Which seems to make sense (large, slow projectile vs small fast projectile).
I assume s in the k1, k2, and k3 is seconds.
