I have a few kids that have attended college on Army ROTC scholarships (one active duty, one national guard, one dropped the program and one currently in college.) My youngest is a freshman in college (so I think I am current) but the compensations has changed a few times over the past 10 years and not 100% positive on the differences between AF and Army.
The offer is tuition books/fees for 4 years (as much as $50K at private/top tier universities or as little as $20K at a state school.) The kid/family is covering the 10-15K board. The student also gets $500/month stipend while school is in session.
There are also places where the scholarship is offered as a 3 year offer. Year 1 the student is in the ROTC program without a scholarship, and the student is then on scholarship years 2-4. Same financial offer... just 3 years.
Good luck to him.