LONG CHIMNEY (BRANCHE TUBE) IN LOW AND BASS WHISTLES TO LOWER THE TOTAL LENGTH AND MAKE THEM EASIER FOR FINGERING
The idea (and patent) of Yamaha with a long chimney or brach-tube just after the mouthpiece and of about 2/3 of bore size compared to main tube was so as to convert close-open acoustics (with odd only harmonics ) to open-open (with both odd and even harmonics). See e.g. https://www.youtube.com/watch?v=LzHasH3Acxw
But it has another effect too: It lowers the total length of the tube. This technique applied to low and bass whistles makes them of considerably shorter length . This will make the covering of the holes with the fingers a lot easier . Even the "pipers grip"might not be necessary now.
In the next photo we see a D4 clariphon (chalumeaux) with along chimney (about 1/3 of the sum-total length of both tubes . The brache has diameter about 2/3 of the diameter of the main tube) which converts it from closed-open acoustics to open-open acoustics. Nevertheless the same technique will make a Low D4 whistles with a fipple a lot shorter!
The next pictures are of corresponding Long Chimney soprano saxophones with cane reeds and sax mouthpieces as the Venova of Yamaha, or Cylisax of Linsey
https://www.youtube.com/watch?v=6wa0mPEmJI0
https://www.youtube.com/watch?v=J0Ka4M_CvVY
https://www.youtube.com/watch?v=1B5fTwSC4QQ
The next pictures are of corresponding Long Chimney soprano saxophones with cane reeds and sax mouthpieces as the Venova of Yamaha, or Cylisax of Linsey
https://www.youtube.com/watch?v=6wa0mPEmJI0
https://www.youtube.com/watch?v=J0Ka4M_CvVY
https://www.youtube.com/watch?v=1B5fTwSC4QQ