[BomberBoy]

Strangely enough, the fire comes not from the engine itself (you can shoot it all you want it won't burn), but from the wing. It's as if the game thought the engine is located not in the place it is displayed, it doesn't happen with Betties for example.

That's because the fire is coming from the fuel tanks, which are in the wings.

As for 6 o' clock attacks and tail gunners, that's the worst possible angle for a fighter to approach from. While you're setting yourself up for a zero-deflection shot, you're also setting the tail gunner up for one as well. Not a good idea! Learn deflection shooting (it's much easier for a fighter than for a bomber gunner who has to take several additional factors such as relative motion into mind for his firing solution) and make beam or vertical attacks. The reason combat boxes work is because while a fighter's jockeying into position for a beam or vertical attack, he's also setting himself up in the sights of another bomber or two. Mutual protection is what it's all about.