Just a couple additional things...
They use to make cylindrical bores in wooden flutes before they made
conical bores. I use to have a really old one. It was louder and the
toneholes were bigger and much farther apart. The conical bore brought
the toneholes closer together, making it easier for women to play the
wooden flute (smaller hands, ie), and lowered the volume, giving it more
of a reedier tone (like with recorders). The cylindrical metal (and some
wooden) flutes have inner connecting levers that open the lids at the
correct location, a shortcut if you will, so that the finger stretch isn't
required. The fingers remain close together, but the actual holes opening
are far apart.
I've never played Northunbrian pipes, but as I understand it, the two
octave range in the cylindrical bore is obtained by adding numerous key
up and down the lengthy chanter...that is, it doesn't
overblow like an
uilleann pipe chanter. Cylindrical chanters reeds can overblow, but don't
produce the perfect octave like a tapered bore. The pitch strays.
The variances in the uneven tapered bore can be used for tuning a
particular note--which would affect the size of the fingerhole required, and
the spacing between holes. The larger the bore, under or just above the
tonehole, the smaller the tonehole...a kind of compensation. The
undercutting in the chimney of the tonehole would also tune the note as
would scalloping the surface of the hole. Keenan undercut his old
Rowsome chanter when he was a kid, trying to tune the notes rather than
getting the reed right, and says he almost ruined it, filing away. But he
discovered it helped him slur or bend the notes easier. Only works for
large bores as I understand.
I don't know what I'm talking about, so take it with a grain of salt.