My sister plays cornet which is in Bb. She has found some accompanying music to play along to. Music from stage shows etc.
I can’t find any in D. If I purchase a whistle in Bb can I play along with her and/or her music accompaniment?
Will all holes covered sound as a Bb? and
will the music show a Bb?
I have other questions along these lines but I am sure you more knowledgeable people out there will probably answer them in posting in reply to this
Cheers
A C whistle corresponds to a concert Bb cornet. If you play cornet sheet music on a C whistle, using the normal D whistle fingerings, the two instruments will play the same pitches (but the whistle is an octave higher, of course). That will do the trick. Trust me. Just remember that you’ll have to half-hole or cross-finger any F-naturals or accidentals.
Yes, there’s more to it than that. But I’ve learned better than to try to explain transposition and transposing instruments in 25 words or less … 
You can only play along with her if she is written in HER key of C (i.e. no sharps or flats) or F (1 flat). It’s really confusing, but basically it would be MUCH easier to have her transpose to you. If you play on a C whistle with concert C music, she would be in the key of D (two sharps). This is all concert pitch and assumes you are playing the actual pitch of the notes written on the page.
Pat
P.S. My “main” instrument is trumpet, so I go through this a lot! This is why I bought a C trumpet for my church work!
MT’s suggestion works fine - my youngest daughter & I sometimes play some tunes together, she on Bb clarinet, myself on C whistle.
You’re referring to the original Bb whistle suggestion, I guess.
Right. But I think most whistle players will treat a C whistle as a transposing instrument in Bb and indentify the notes according to their “normal” D whistle fingerings, not concert pitches. In which case, the Bb cornet (or clarinet, tenor sax, etc.) doesn’t need to transpose.
Of course, this does work best if the cornet music is in one of the standard whistle keys - D, G, A, etc. Otherwise you need to either fudge the non-diatonic notes, or pick a whistle in a different key and transpose the dots. And when it comes to show tunes, chances are you need to do some finger twisting on a diatonic whistle in either case.
As I said, 25 words or less … 
MT:
I think this is WAY to confusing to explain via email!!! 
Pat
So on a C whistle, does it play a C when you have all holes covered?
if all goes well 
C XXX XXX
D XXX XXO
E XXX XOO
F XXX OOO
G XXO OOO
A XOO OOO
B OOO OOO
Right … Except you pretend that you’re playing a D whistle, and you finger the written notes accordingly.
oh! I like pretending!
do we get to dress up?
As long as you don’t transpose dress. 
Ya know I’m just a tease
The defense rests.
Keep whistles in all keys, and play by ear. (Nine words). Whoops, now eleven…whoops again, better quit while I’m ahead.
(21 )
I bow to your masterful concision, CT!
Though some show tunes might be a bit challenging by ear, e.g. something like Rent.
What if the song/tune CHANGES KEY in the middle. So many of the pieces I want to play do that.
Hmm, can you give some examples?
Most Irish dance tunes don’t modulate out of the mode they’re in, even in the tonic center seems to change. You do sometimes have to deal with chromatic tones, supernaturals, etc., but that’s an issue anyway, whether you’re changing whistles or not.
Of course, trying to play, say, an Ab tune on a D whistle is an exercise in madness.
Considering the inclusion of a TRUMPET I was under the impression that the music being played was NOT iTRAD but more on the contemporary bent which is where I spend my time playing now.
An example: Jesu is in the key of G. It does not change keys (at least not in the notation) but goes into a section with LOTS of accidentals. I can ALMOST half hole and cross finger my way through it.
Aha. Yes, that modulates to Am/Cmaj (and briefly to Fmaj).
Not sure Bach would be considered a “contemporary bent”, unless you’re, like, the Highlander or something.
NO! NOT HIGHLANDER PIPES!!!
Anyway, my main gist was that I am NOT a trad player and it was just an example of what I have come across. Looking into something more chromatic since my wife plays piano and is not into trad either. Looked at the strathman, VERY briefly. $$$$$$$$$$$$$$$$$$$$$$$$$