Plus a few thousand hours of time in complex high-end aerobatic aircraft including jets like the L-39 etc. A private pilot certificate is simply a "license to learn" and nothing more. I never said you were stupid but rather that you don't know much about the subject. There is a difference between stupidity and ignorance. You're ignorant, not stupid. Ignorance can be corrected if the person is willing to move forward. Stupidity is the unwillingness to change their mind or the tendency to get hostile when someone tries to teach them. Then you don't fully understand the complexity of them. That should scare you. One of my first flights was given to me by a world class test pilot who I later asked about what it was like to fly things like the X-15. He told me that you should never hire a test pilot who says they are not afraid. "That usually means they are crazy, stupid, lying or oblivious. None of those is something you want in a person with their hands on the controls". If one wishes to split hairs but in common vernacular, supersonic is anything beyond 1.0 Mach. The point is that wing design gets exceptionally complicated whenever you get anywhere near transonic. Once you get into the transonic range, that's where sweep starts to be useful.