Hello

Wonder if there are variable pitch (controlled via RC) for small props (e.g. 22")

Yes, I have seen ( here in rcuniverse) pictures of a variable pitcht 3-blade prop on a 100" wingspan turboprop Tucano build by someone in Austria. You should search for tucano, or turboprop or even variable pitch. Sorry for not being more specific. Good luck.
geared

There is a place that makes a prop that the pitch may be changed however it must be done while not in motion. I believe it would require some sort of hyraulic pressure to change the pitch when airborne.

or a heli setup... I've seen some variable pitch setups that basically use a pitch slider and swashplate from a rc heli... no hydralics, just one extra servo.

http://www.jakadofsky.com/htm_en/welcome.htm

Solo props also makes an ground adjustable prop.

http://www.soloprops.com/index.html

Grinder.

Not bad.

Don't really fancy the helicopter setup ..... might get really flimsy at higher revs right?
But I do like adjusting the pitch on the fly.

Wonder if there are ready made systems that we could buy.

Updatez .............
No ready made var pitch prop???