Is it calculator or simulator?
This is a simulator. It uses the combat engine of the game. Due to the random battle order, you receive an overall idea of what will happen in the real combat. The only ships with fixed battle order are the Transport ships and the Solar satellites. They always stay behind. The size of the recycle field varies also between the fixed percentages. They are different for the different universes. You can simulate all kind of battles with ships, defences, with or without ship levels, attack and defence bonuses, different rounds etc.
Why I get a black page instead of a simulation result?
You left a blank field somewhere. All field must have a value at least 0.