If you have patches and/or pictures, you can maybe use them to help determine your Vet's rank and what unit your Vet fought with. The B-24 Best Website has pictures of patches of almost all of the major air forces and many of their Groups.

If you don't have patches or insignia, do you have any citations, ribbons or medals you can use to determine what specific air force he fought with? Ex., if he received the Philippines Presidential Citation, you can be assured that he was a member of the 5th AF and not the 10th AF or the 8th by using the chart here at this site. For pictures of various ribbons and medals, try here: Air Force Awards and Decorations (to learn a bit about how the Air Force used medals as symbols, see the bottom of that page).

Are any pictures left behind with planes in them so you can ID the planes? If you are unclear as to the different types of planes flown in WWII but have a picture you can work with, go to this site  http://www.csd.uwo.ca/~pettypi/elevon/gustin_military/ and see what you can see. Look closely at the tails of any plane pictures you have: can you see any nose art? Any tail markings? (last two links take you to particular pages at the B-24 Best Website). If you can identify the type of aircraft, go to this site's links page for links that might help.