Were you planning on going to college if not accepted to the air force? If yes, then it's the same thing. What makes it difficult, is as CadC mentioned, all the other military activities involved. But that's a double edge sword. The military part adds a lot to your plate. However, the military part takes away most of your off duty time mon-friday. So that means you'll have plenty of time to do the homework and classwork.
Think of it as how do you compare the IB program or a full course load of AP classes to regular classes that the majority of kids are taking. That is how you can compare the Air Force Academy to a traditional college. Or; equate the academy to an ivy league school. They are more difficult than a traditional college; however for numerous different reason.
But now compare the positive side. Imagine that you were put into the IB program or taking a full load of AP classes. It might seem to difficult. Now, image that your parents grounded you from all activities during the week and you weren't allowed to go out except on weekends. Well; then you'd have plenty of time to do that IB program or full AP course load. Well, that's how it is for the academy. Until you're a senior, you're basically restricted to the academy Monday-Friday. When you're no in class, you're pretty much just there. You're not going to the mall, going to a movie, going to your girl/boy friend's house, etc... So you have all the time in the world to do your homework and classwork.
On a positive side; there are a lot of IC (Inter-Collegiate) athletes who not only has the same exact classes as you; with the same amount of homework and classwork; etc... but they even have LESS TIME because after classes, they are usually training/practicing for 2-3 hours each day. And yet they survive too.
Yes, it helps if you are an academic brainiac. But you don't have to be. The number one thing to learn/develop is "TIME MANAGEMENT". If you can learn how to organize your time vs tasks; and aren't A.D.D. and easily gets distracted from what you should be concentrating on; then you will be fine.
Academically, the first year is pretty easy. They are overloading you with military stuff, so they back off a little with academics. 2nd year; according to MOST opinions, is the most difficult academically. The 3rd year is better because you are working mainly on your major. 4th year is a blur. So many things happening; putting in for assignments; summer trips; basically finishing up required classes; excitement; anxiety; etc.... You go to sleep in September, and when you wake up, it's May and you're graduating. It's like; "How the hell did I get here?" Best of luck. mike....