I was having difficulty in reaching the top octave note on my 3 holed duct flute, I am guessing the mouth piece was at fault as it was not made for those dimensions. So I thought an open-ended mouth piece might be possible?
The open-ended mouth piece is used in the Ney and Kaval type of instruments, basically you blow across and down the rim of the mouthpiece into a cavity…like blowing into a bottle.
The 3 hole flute uses the same system as the kaval (overtone system) so by blowing harder you achieve a 2nd register. But the normal 3 holed flute has a fipple or duct mouthpiece, like a recorder.
So I experimented with an open-ended mouthpiece and it worked just fine. I can now reach an octave, and even notes below.
I joined this mouthpiece onto on old body, so the measurements are not correct for it to be in tune (concert pitch) but it plays ok by itself.
I am now working on refining the mouthpiece.