Are branches of the Armed Forces subject to the Freedom of Information Act?

You can request anything you want. The Air Force can pretty much decide if they want to release any nonclassified information or not. If it is classified information, it will not be released.

And if they do decide to let you see it, you many not be allowed to make or keep copies or photographs of what they let you see.

UK here. When I was younger and my dad was in the army my mother worked (for a very short time) in the Officers Mess and she had to sign the official secrets act. Crazy World We Live In.

It’s not the place to request general information.

You have to ask about existing records. “You should be aware that the FOIA does not require agencies to do research for you, to analyze data, to answer written questions, or to create records in response to a request.”

Federal FOIA FAQ
http://www.foia.gov/faq.html

FOIA sites for the branches
http://www.armyg1.army.mil/foia/
http://www.foia.af.mil/
http://foia.navy.mil/index.asp
http://www.uscg.mil/foia/
http://www.marines.mil/unit/hqmc/foia/