How Factory bombing works
Strategic bombardment is a single-purpose mission with the objective of laying waste to the enemy Research, Development and Production facilities, hence the acronym RDP bombing, by the use of multi-engine bomber aircraft. These targets are found deep in the enemies rear territory, in the form of factories.
Because the factories are highly valuable assets, enemy fighters are very likely to rise to their defense. Therefore RDP bombing missions are best projected by groups of bombers, preferably with a host of friendly fighters as escort. A single bomber may get lucky and sneak through unchallenged, and a small force of 3-4 bombers may succeed too once in a blue moon, but for a lasting effect and added security the strategic bombing mission requires a great number of players working in concert. Know this before setting out on your mission!
In the current version (1.33) damage to factories reduces the rate of production corresponding to the amount of damage sustained, slowing the resupply of material to front line brigades up to 18 hours when normal resupply is 9 hours (Example: when a plane is shot down that plane normally takes 9 hours to rebuild, but with 100% of the factories down that plane would now take 18 hours to resupply). While this delay may seem slight it may nevertheless be a crucial factor in a sustained battle where troops use up material at an accelerated pace. In the past Research & Development was also effected by factory bombing, but that feature has been suspended. Each factory percent adds to the enemies supply, thus a sustained effort is required to slow down Production as factories rebuild in between attacks.
The governing factor for factory destruction is joules of explosive delivered within the factory square (that is, inside the four walls of the factory “tile”). You need not hit the actual factory building to generate damage. To this end it is appropriate to throw the heaviest and most explosive-packed bombs at the factories. Explosive content differs greatly between bombs – know your megajoules. Consult the bomb weight table for clues in this regard.
One last thing: In the game you can type out ".rpd" in chat window to receive current production stats for all sides. For a individual factory status, locate the factory of interest, click on its icon, and type ".own" for its damage state
*Taken from WWIIOL-Wiki, also take a look at Strategic bombardment overview for more information
Axis Factory Data
Factory Buildings: 2 Facilities #3, #4 City Altitude: 125 feet / 38 meters
Factory Buildings: 2 Facilities #5, #8 City Altitude: 161 feet / 49 meters
Factory Buildings: 4 Facilities #1, #2, #6, #7 City Altitude: 295 feet / 90 meters
Factory Buildings: 1 Facility #9 City Altitude: 377 feet / 115 meters