I unlocked the big 132 rockets for IL-2 and some of the unlocks for the IL-2 is to destroy ground targets, which is impossible because the plane is crap. No more powerfull than a spud gun.
The only thing it is good for is on the CTA games, i'm not sure if someone who is landed counts for a ground target? Should do. I've definately killed more than 5 landed people with an IL-2 and not unlocked anything.
Doe's it matter how you bomb? How high? Dive bombing?