I have good luck against aircraft until fall '44. I think my tactic to run straight until they commit, then hard right, works very well. My gunners have been very good and I have knocked down up to 9 in a single patrol to my assigned grid. I do dive when there are 4 aircraft or more - but only after their first pass. At that point we may have reduced their numbers. Plane type does matter. I always center the rudder after a pass. Then I repeat the above on their second run. Hope this helps. Only lost one man to aircraft in three years. I am a very conservative tactician.
__________________
DID, no cheats, no shortcuts, no non-historic equipment deviations. Boat and crew safety is integral with my immersion style! Follow the historic events during your patrol:
http://www.uboat.net/today.html