The following formulas are used if AllowAlternativeCombat is off. In this case, all results are integers, weapon hits do at least one point of damage.

Shield_damage =
   Trunc(1.5 + ((Expl_Power * Eff_ShieldDamageScaling
                + Kill_Power * Eff_ShieldKillScaling) / (Mass + 1)))

Hull_damage =
   Trunc(1.5 + ((Shield_damage * Eff_HullDamageScaling / (Mass + 1)))

Crew_killed =
   Trunc(0.5 + ((Kill_Power * Eff_CrewKillScaling) / (Mass + 1)))
   ...at least 1 if the weapon emits Death Rays.
This is a testing version.
It may be incomplete, and have more bugs (or features) than the public live version at planetscentral.com.