Today I made a major breakthrough on my flute. This 3D printed flute is actually a lovely instrument, with a nice tone, and a robust low D. I just wasn’t playing it correctly.
The thing I was missing was placing the flute under my lower teeth. I had been cramming it up into my lower teeth instead of resting it against my chin. Somehow this meant that the low D was very weak: I was overblowing it into the next octave every time I tried to play it. Now that I’ve sorted this out, I can nail the D every time.
Curiously, what I did immediately before this was to rotate the flute head a full quarter-circle toward me, so that the embouchure was about even with my left thumb. This allowed me to blow straight forward into the flute, using the side-of-mouth muscles I used to play oboe. Once I was convinced it was possible to make a nice low D this way, I was able to rotate it back and get it the traditional way.
Maybe there was more to figuring this out than I realized. But in any case, I can play two full octaves reliably now, which should help quite a bit in my progress. Thank heavens!