Hi,
I’m in the process of getting a flute in some other keys, maybe G, my question is, will there be any hurdles involved regarding embouchure, my D flute embouchure is fine and getting better everyday, I only ask the question because I have a delrin/resin keyed Bb flute/fife marked made for Boosey which I am seriously struggling with, it is quite slender, all pads are sealing, the embouchure is definatly eliptical egg shaped, and the body thickness at the head is thick, when you look into the embouchure hole you can see some under cutting, so its not a straight drilled hole, the cork is exactly right, in as much as its 13.5 mm from the center of the embouchure hole which is the circumference of the fife/flute, if I focus my embouchure ( seriously focus ) I can get some high notes, the lower octave notes are not there at all, no matter what I do.
my query is not so much about the Bb, but more about smaller flutes i.e key of F and Key of G, do you need to retrain your embouchure to be more finely focused to get a good sound from flutes in these keys.
as usual all help greatly appreciated.
sponge 
The embouchure hole on smaller flutes will be smaller, requiring a more focused blow, and the smaller bore will give more resistence. The combination of the two make fifes and piccolos usually quite difficult to play properly. Flutes in F it should be much easier though, but it also depends on the individual flute…
I play G flutes, A flutes and Bb flutes a good deal. They are more demanding to sound
but with practice there is no difficulty. It takes more strength and focus and is great
practice for improving embouchure generally.
It may be there is something the matter with your particular flute.
I would try another. Usually the lower notes are easier to sound
than the higher ones.
I’m getting about 9-10mm on my short flutes and 10-11 on my longer ones. The Healy fife would have perhaps one of the bigger “sweet spots” due to the rectangular shape. But that is with a limited selection.
Embouchure holes on smaller flutes are certainly usually smaller than on concert flutes, but not in proportion to the overall size reduction. Yes, your focus needs to be better, but not to that drastic a degree. If the Bb one you have isn’t sounding OK in the low register, I’d suspect a problem. You describe classic leak symptoms. Have you checked the head isn’t leaking as well as the body/pads? A leaky cork is no good however correctly it is positioned! Also check the assembled flute to see if the joint is OK (and check the tuning slide if it has one). I doubt that it is your embouchure that is the core of the problem you are having.
That said, the second flute I ever owned is a modern (1960s?) Premier (as in the drums?) blackwood 5-key Bb band flute - and I have always found it difficult to get to play compared to other Bb band flutes I’ve had, though there is certainly nothing “wrong” with it.
Generally I’d expect someone with a moderately proficient embouchure to find a treble G or F flute easier to play than a concert flute.