There's a rather straightforward formula for determining how much DPS you do to a base.
If the base is fully stocked with all three repair commodities and shielded: (K*45000*0.03*20 - 180000*L)/20
If the base is only stocked with one repair commodity and shielded: (K*45000*0.03*20 - 60000*L)/20
In both of these equations, K is the number of battleship cerberus cannons being fired at the base. L is the core level of the base.
Example -- four battleships with 3 cerbs each (standard for heavies) against a stocked, shielded core 1 base:
(12*45000*0.03*20 - 180000*1)/20
(324000 - 180000)/20
144000/20 7200 DPS
Time to take down base: 18.5 minutes.
