The Ostwind in Aces High II
The Ostwind is one of two mobile AA guns based on the Panzer IV chassis. Its brother, the wibelwind, is armed with 4 20mm cannons as opposed to the single 37mm gun carried by the osti. The ostiwind can kill panzers, and other flackers from behind at close range, but you would do better leaving enemy GV's for your own tanks, and concentrating on the aircraft. The maximum range you can reasonably expect to land any hit at, even by luck, is 1.5k, anything further and you are just wasing ammo.
Fighting in the Ostwind
The wirb is more common overall, as you have a higher volume of fire and better balistics, but you're about as likely to see an osti at a V base, or at a spawn being attacked by B-25's, or Il-2's (both are slow aircraft, that can absorb enough damage to make the osti useful). You also have a 7.62mm (.30 cal) hull gun, but this is never usefull unless you're turreted and see troops running. You're unlikely to escape well aimed bombs, so you're best bet would be to find some thick trees and reverse into them. This will shield you strafing, and bomb blast to a limited extent.
Fighting against the Ostwind
Just drop a bomb on its head. Most gunners seem to have trouble aiming at targets in the verticle, and this is only accentuated by low rate of fire, and worse than average balistics. This may sound harsh, but if you are in a B-25 or Il-2, wait for his attention to be drawn by someone else in the opposite dirrection, and then go for your pass
-The ostiwind is unlikely to hit you at even 1000yds, as poor balistics and low rate of fire make finding the right lead a problem.
-B-25's, Il-2's, and other large aircraft should be cautious of the ostiwind, as just a few hits will be enough to seriously damage or kill you.
-stay clear of multiple flackers in close proximity, the volume of fire makes hits near guaranteed.