[dragonwriter]

> But again if you want to get technical, the Constitution restricts Congress's authority to provide for the common defense to having an army or a navy, but not an Air Force

It allows Congress to raise "Armies" (plural) and a Navy, and it allows Congress to choose how to equip and train the Armies it raises. I don't see that it prevents it from choosing to a equip one of the armies primarily with fixed-wing aircraft, training it in doctrine for employment of such equipment, and give it the name "Air Force" to distinguish it from other armies that are differently equipped and trained.