I never attack B17s from anything remotely approaching the 12 OC position. For B17s I generally attempt to set my run up so I am flying parallel to the bomber, then dive in perpendicular and come back up on the other side. Generally I aim for the wing root, although I usually end up walking the hits from the nose to the tail. In the 190A8, this works very well, since the 2x30mm will pretty much take a wing off on one pass. It doesn't work so well in the Dora, it lacks the firepower to do it.
Against Lancs I usually do the same thing, although I will go HO with a Lanc. I usually attempt to dive below the Lanc so that I can pull through the merge and fire along the underside of the fuselage. That usually works well, even in the Dora.
Against B26s I either go for my typical B17 pass (but lower, since the 26 has no ball turret), or I do the above pass as if it were a Lanc.
In a Dora it almost always takes 5 or 6 passes to bring down a B17 using the side approach. B26s are usually good for 2 or 3 passes, and I've gotten all sorts of different results against Lancs (From them blowing up in one pass to taking eight or more runs).
Lastly, I like to intercept bombers as they are approaching their target. You can come in from the rear without much danger, as they are looking through the scope, and not out around the plane. I almost always can kill a bomber in one pass if I manage to catch him on the bomb run.
