On the tune “Sovay” the music says “for D Whistle.” It is in “G” but I’m cool with that. Cnat an all. But (and here’s the confused newbie in me) what I am supposed to do when the tune drops below “D” as it does for three notes?
Pastorkeith
cheat…ah, just play the too low notes up an octave
Right. Shifting octaves when the tune is out of range is known as “octave folding” – a nicer term for cheating. 
It’s a necessary skill on whistle, flute and pipes. Sometimes it’s a bit more complicated, and is best done on a phrase by phrase basis.
For example, the tune you cited, Solvay. If the key sig is one sharp, it’s probably in E Dorian mode, and the line in question something like: |zGEE F2D2|B,CDE|. Here, it might sound best to shift the entire second measure up an octave to preserve the contour: |zGEE F2D2|Bcde|.
Of course, if you’re playing solo, another alternative is to transpose the whole melody up to place it within the range of the instrument. For example, Solvay played in A Dorian would fall within the whistle’s normal range.
I like it! I’ve always called it “aliasing”. (Since it’s past the whistle’s
Nyquist frequency… oops bad engineering joke. Sorry.) Instead of
jumping the octave, I also sometimes go to a different note in the
chord.
there are a couple of songs that i play with a group that the lowest note is a C. i just play the D and no one has ever even noticed. this won’t work with all songs but is an option.
Mute: you prolly get away with D iinstead of C because it’s a low volume note on a whistle. I prefer to find a harmonizing note, or jump an octave if that works, or jump a section of the tune up an ocatave. All this has been said before.
I dont yet play whistle (should be soon) but I do have plenty of music experience. If you come across a note out of your range, you can take it up an octave or play a harmony note (which I prefer because I find the jump up an octave to be distracting to the listener many times). Just make sure to note the key the song is in and figure out what will harmonize with the group best.
Edit:
And it appears I was beaten to it
That’s what the low D whistle if for. Whip it out and play the offending note, then switch back to the regular d. You might try taping the two whistles together for convenience. That is NOT the same as taping two regular d whistles together for make a low D whistle.
Or taping two midgets together to make a basketball player. It’s not that either. The midget on the bottom can’t run worth a darn with the extra weight. And he (or she) generally isn’t steady enough so the one on top can shoot either.
If the key sig is one sharp, it’s probably in E Dorian mode
Actually that’d be minor/Aeolian; Dorian in E is two sharps.
Oops … that’s right.
vomitb’s comment reminds me to add that “octave folding” is definitely NOT the same as “whistle folding” – a procedure involving a bench vise, pliers, and a heavy hammer, which is likely to significantly alter the fingering of the tune.
As for aliasing, I thought that meant scraping the label off your Generation whistle and telling everyone it’s a Copeland.
Thank you all!
Excellent suggestions -
I am armed and ready - to attempt that tune - one more question to scratch off the list.
Now if I can only figure out when I play a tune written for a whistle’s second major scale say “F” with a b flat whistle - do I just change the fingering on just the one note (play an E natural ) and read the rest of the notes the same with the same fingering or does everything change? I’ve been to the fingering and keys sites and the concept makes my head ache. And why should the makers of Tylenol get so much of my money anyway?
Pastorkeith
Hmmmmm…
Some confusion here. First of all, the “second major scale” - the one that starts on XXX OOO - always has one less sharp (or one MORE flat) than the first major scale (the one starting on XXX XXX). So for a Bb whistle, the second key is Eb (the OXX OOO note will be Ab), not F.
If you want to play a tune in F, you want either an F whistle or a C whistle (the OXX OOO - or other alternative) is Bb on a C whistle.
I’m not sure how to approach the rest of your question. I think you’re asking whether all the notes are different for a given fingering on one whistle key vs. another - and they are. How to cope with that leads to at least a couple of strategies - one is just to learn to read for each whistle key.
That’s the natural approach for those of us who come to whistles from recorders where, unless you’re REALLY into early music, there are really only two sets of fingerings to learn - those for which the bell note (all fingers down) is C - soprano and tenor and great bass, and those for which the bell note is F (sopranino, alto, bass, etc.). But of course on whistles there are as many sets of fingerings as there are whistle keys, which complicates things. 
Personally I’ve gotten to where I can read music pretty easily for D whistle and less well but passably for C whistle and when I play a hymn tune or whatever with another whistle key it’s pretty much by ear. So, the result is I can play tune or parts that I don’t already know pretty much by heart on a D whistle, less well on a C, but I’m out of luck on other whistles and have to reach for a recorder to actually read it and learn it first.
Who knows what I’ll be doing a year or three from now as I expand the use of various whistles.
More confused now, right?
I treat the whistle as a transposing instrument and play all whistles as if they were D instruments regardless of their real key. This means the occasional transposing of music if I can’t play the piece by ear, but transposing music is very easy to do.
I think many people take this approach and it does make things easier than learning lots of different fingerings.
Mute: you prolly get away with D iinstead of C because it’s a low volume note on a whistle.
…or, get a D+ whistle and call it a day. They play like a normal D but includes an additional hole for C below D that is played with the pinky if desired. Both Busman and Silkstone make 'em.