Hi everyone,

I've been playing the flute for a few years now. For the last few months, I've listened lots of recording of roland kirk and ian anderson, I noticed that their solos have a really airy sound. I've tried copying that style of playing, but I couldn't figure out how to do it. Could someone explain to me how it is done?

I believe that if you investigate, both performers were more self-taught than is the norm. for flutists and they are both using amplification.
As such, they are probably doing a combination of two basic things.
1) Relaxed (or non-existant) facial and lip muscles and
2) They are probably blowing their exhaust directly at the microphone.

and oh yes, they may be also singing or humming along which may have caused them to dilate their embouchure inadvertantly.

Hear Kirk at the beginning esp:
http://www.youtube.com/watch?v=_q8Ye58uL5o&feature=related
He's doing lots of humming along ........but not always.

I am sorry i do not know, cause i play the violin but these people above me ^^ said it all.