Bomber attacks...
What works for me is as follows...
1) come below them about 1k-1.3k, out of range of their 50 cals.
2)once you are in front of them but still below them, (make sure you have lots of speed, like 300+mph), pull straight up, roll 90 degrees and shoot them as the cross overhead.
3)once above and behind them, pull back on the stick basically doing a split S and go straight back down, gain speed and repeat.
Tips: * wait till you see the bombers when looking out of the 'top-back' view before going vert.
* Most bomber pilots aren't looking below, but instead behind, so they often don't see you if you stay below them during your approach
* Lancasters don't have guns on their belly, so the have no defense.
* When rolling 90 degrees as you climb, this lets you see the bombers more easily as you can seem them come from the right-to-left or left-to right and as you pass them from behind you are giving them the 'knife edge' of your plane making yourself hard to shoot at that critical weak moment when you are slow.