I've been reading the various threads on RCU related to turbo prop models for the last year. I noticed that both sandor and shockwave have mentioned the performance / technical challenges of going with a constast speed / adjustable pitch solution.

If you have a spare hour, check out this thread if you haven't already seen it.

http://www.rcuniverse.com/showthread...ght=turbo+prop

This guy has built a variable pitch prop mechanism of his own design. He's been working on it for over a year. The thread captures the development process complete with all the failures in between. The control unit in the turbine maintains a specified RPM (say 150000). As pitch of the prop is increased, EGT increases to a point where the turbine will shutdown. He explains how he had to learn some new flying skills to get used to the prop-pitch on the throttle control.

He's posted several videos which may still be available.

Jasonn