I was just wondering, would there be any mileage in trying something like a Tipple-Fajardo Wedge in a whistle … or has it already been done?
Did a quick search after considering this myself the other day and came up with two threads among all the others relating to the Fajardo wedge for flutes…
https://forums.chiffandfipple.com/t/driving-in-the-wedge/51753/1
https://forums.chiffandfipple.com/t/fajardo-wedge-question/45983/1
Did a quick search after considering this myself the other day and came up with two threads
… thank you Peter … me just being too lazy, or using the wrong search string 
I’ve tried some Gonzato-style whistles with a “toe” extending out from the bottom of the fipple block, under the window. The toes extend 1 or 2 cm beyond the fipple, and taper from about 5 mm under the fipple down to nothing. This narrows the bore at the top end. It appears to have the desired effect of bringing the octaves into closer tune. If overdone, it can also make the sound thin, particularly on higher notes.
There’s no easy formula for how big to make this. I was working from equation 16.59 in Fletcher and Rossing’s The Physics of Musical Instruments. On narrow-bore whistles, I don’t think you can make the wedge big enough to truly balance the octaves (all by itself) without destroying the sound. I haven’t tried lower, wider-bore whistles yet.
Now, my question is … what other adjustments will bring the two octaves into closer tune? The good makers have shown that it is possible.
I’ve experimented with various methods along the lines of the wedge on whistles. You can read some of my thoughts in the first link that Peter referenced.
My current conclusion remains the same on high whistles. A wedge or other device is not really necessary. There are easier ways of shaping the internals of the head which do have the same effect. It’s not a wedge or spike that have the effect but restricting the bore a bit as it approaches the window. Nesting a tube inside another tube can have a similar result. Remind you of any current whistle designs?
Low whistles benefit more from reducing the bore near the window, IME. Tunborough makes good points from his experience. So it’s a balancing act. You still have to design for the second octave at the outset.
Ever wonder why the Overton type whistle has those flat sections near the mouthpiece?
Feadoggie
Ever wonder why the Overton type whistle has those flat sections near the mouthpiece?
Feadoggie[/quote]
It appears the flat sections on an Overton do the same as wings/tabs on the fipple/plug of a Chieftain.