I find the best way to kill the IL-2 is to dive from behind in a shallow dive that takes you low and about 50-100km faster than the Sturmovik. You should be at his 6 low.
You then fly to underneath and just behind him and pull up, lining cannon fire all the way up his underside. If you are flying the G6 with the 30mm nose cannon you can kill him this way at little risk to yourself. If flying a G2 etc. it may take a couple of goes. Generally you can blow off his tail.
If you are in the IL-2, a hard wingover will give your rear gunner shots at the pursuer and make you hard to hit. Even better, perfect the art of "shaving", or flying very close to the ground, which is what the real pilots did.
Ian