Just wondering …
Has anyone ever experimented with a Concave face on the stopper ?
I was thinking last night that a concave might result in a ‘smoother swirl of air’ (? 
) inside the Flute …and perhaps resulting in a different sound ? ..
Any thoughts ?
Theory suggests a concave stopper would make sense. We are talking a cavity here, not a resonant length, and so a “round bottomed flask” should offer fewer impediments to filling and unfilling the cavity every cycle.
Encouraged by the theory, I made a hemispherically-faced stopper some years back, but couldn’t detect any advantage.
Stoppers are strange things. We go to a good deal of trouble to ensure they are airtight, and yet a small hole through the stopper doesn’t make the flute play any worse (I’ve tried it.) Some even claim it makes them play better, but I couldn’t detect that either. It probably makes sense if you remember that it is a cavity - the impedance of a small, relatively long hole (when compared to the relatively massive wide mouth) means negligible leakage through the back of the cavity in any one cycle. Make the hole big enough (or short enough) and the stopper cavity will stop working its magic, and then flute performance does start to suffer.
Terry
Nice one Terry…thanks…I dont think I’ll try for a concave now.
One thing I did though, was to put a smear of Zap-a-Gap (a thickish super glue) on the face of the cork to counteract deterioration due to moisture..