Hi David,
>>How do you get notes that high on a flute? Overblowing?

I played tenor sax. By tightening up real hard on the reed, I could actually reach a full octave Plus 4 half tones above the highest note on the sax. ( I was a Maynard Furguson fan ).It used to drive the other sax players nuts. They could handle the 4 half tones, but none could go an octave higher.
Good luck with the national debt!
Fred