RE: Heli stuff and fellowship
Yah-placement of the electronics is real important and sometimes it's hard to decide just where to put everything. You have to consider EMI problems as well as cooling and balance. The precision and challenges of these little birds is what makes me love them. I'm looking at a completely new set of ?s with my scale project. It's gonna be fun.
That rudder design on the EC120 is called Fenestron. It's a ducted fan that is shaft driven by a variable speed transmission/clutch assy. that is powered by the main engine. The difference from a tail rotor is that the pitch and speed both change. It speeds up and slows down independant of the main rotor in coordinated amounts with the pitch to change the antitorque thrust. It's the newest technology for rudders on helis and has been proven to be very powerful, efficient, effective and vibration free. Being enclosed like it is it's not affected by rotorwash and creates a strong thrust of air that can be more precisely controlled. The blades you can see in the photo I posted before are the stationary vanes on the outlet side of the fan. The fan itself spins so fast that not even a fast camera can capture them. Below is a photo from the tech manual that better shows the fan assy.