Hope that someone will answer me this rather silly(?!) question that I have asking myself for a longtime:
“why are there so many range of flute like D, Bb, Eb, C etc?”
-What are the advantages of not only having D flute but the others?
(some pieces are played with non D flute)
-How many non D flutes are enough?
-what do you recommend to get as the second flute? (I have a D flute)
Thank you in adavance!!
A D flute can only play in the keys of D and G and their related keys.
If you want to play other keys and don’t have a keyed flute you’re pretty much out of luck. THe other keys you will need depend on the keys of music you like to play. 
I had a Eb for a while but found little use for it as very little of the music I play is in that key. I have an F flute which I find very useful for F and Bb.
If you want to play in a lot of keys you have three choices.
A keyed flute
a 10-hole chromatic flute
A lot of flutes.
Patrick Olwell makes really wonderful bamboo flutes in many keys that are fairly inexpensive (less than $100). 
Skip Healy Makes a 10-hole chromatic flute in F or D. I’ve never tried one but I do have one of his 10-hole fifes and it’s quite wonderful.
Everybody makes keyed flutes they are wonderful and expensive.
Doc
Doc
Tchie,
There was a lot of interest in Eb some years ago, and flutes in that key are a real pleasure to play. Bb seems to be popular these days due to Molloy and Crawford.
A number of old flutes were made in unusual keys (by modern standards) for marching bands - F and Eb, and fifes in B or Bb. Bate refers to the “flute d’amour” pitched in B which was popular 200 years ago.
Flutes in odd keys are handy for playing with flat pitched pipes these days. The Eb is nice to have for a round of solos in a session with a number of flute players, the Bb is pure self indulgence. Getting a flute in one of these non-standard keys depends who you play with.
Ken
Thank you very much indeed Doc and Kenr!!
(I thought the question I asked was too silly to get reply…)
A D flute can only play in the keys of D and G and their related keys.
I realised this through looking for some tunes by woodenflute.com, for exactly same partition, I observed that the key was for D, sometimes, G…
If you want to play other keys and don’t have a keyed flute you’re pretty much out of luck. THe other keys you will need depend on the keys of music you like to play.
I have 6 keyed flute… other day, I tried to learn Flook’s “The North Star” (beautiful one, I love this tune) through the CD, I listened many time and I end up with going to get Eb tinwhistle in order to play… (I do not know how to play this tune with D flute, well I can, by changing the code but it is not same for me!)
I had a Eb for a while but found little use for it as very little of the music I play is in that key. I have an F flute which I find very useful for F and Bb.
Tunes played by Flook are for Eb, I thought…
Patrick Olwell makes really wonderful bamboo flutes in many keys that are fairly inexpensive (less than $100).
Excellent flute but… how long the waiting list? 
\
Bb seems to be popular these days due to Molloy and Crawford.
I tried Bb when I was lookinf for Eb flute… I felt like the sound was inbetween tin whistle and low whistle…
A number of old flutes were made in unusual keys (by modern standards) for marching bands - F and Eb, and fifes in B or Bb. Bate refers to the “flute d’amour” pitched in B which was popular 200 years ago.
wow!! you are living-dictionary!!
Well, “The Dark Haired Lass” played by Hammy Hamilton (The Moneymusk) is also by Eb flute, is not it? The sounds change, but the fingering is exactly same as when we play with D flute… thus I may say we can play with any flute if it sound nice?
Olwell is currently taking orders for the bamboo flutes. The waiting time is quite reasonable (probably weeks or months) give him a call.
Also, the Bb flute Kenr is referring to probably Bb below low D…one octave lower than the whistle you mentioned.
Doc
Tchie,
just to follow up earlier points, whichever key the flute is pitched I always use the same fingering. There’s a nice example of Bb and Eb dueting on “The Kilarney Boys of Pleasure” on one of the cran CDs with Desi & Ronan swapping between keys to give a magical combination of tones.
In a regular session, within reason, tunes calling for Bb, Fnat or G# can still be played on a fully keyed flute in D. Some of Paddy Fahey’s tunes, Paddy O’Brien and Ed Reavey’s are in odd modal shapes which you can’t really do just by shifting the pitch of the instrument.
Ken
Ah… it is became much clearer on my mind… thank you all!
Ok, we have range of flutes and we can play with same figering… how about other musical instruments to follow that?
Also flutes in different keys have
different voices–in a way, they’re
almost different instruments,
and this is intriguing.
Some more reasons for flutes pitched other than D:
C#, C, B, Bb: so you can play with pipers on their flat sets.
Eb: so you can play with those who tune to it. There a numerous recordings of fluteplaying pitched in Eb. I hear that Eb is very responsive, a different instrument altogether, as some would have it. I’ll have an Eb stick some time this year, so I’ll have a chance to find out for myself.
Nano,
getting an Eb will revolutionise your playing. It really lets you open up, and doesn’t ask for much air for a rock hard tone.
Ken