Hi John,

I'm no control system or servo designer but I do know the dynamics are quite complicated. Controlling the RPM at a given value is not the problem, it is the requirement to change the desired RPM quickly as we move the stick quickly. Measuring the RPM cannot be done quickly. What you read out is an average of some number of cycles over time. To have the desired frequency response you'd need to measure angular velocity many times per revolution. Then with the high inertia you'd need lots of change in torque in both directions to control the angular velocity.

Having said all this, I'm sure it will be done eventually. Right now I still feel the advantages of the electric system far outweigh the change in "throttle feel" from the beginning until the end of a flight. The guys that practice can control the speed as well as the path of the aircraft. I'm still working on the path as well as he speed.

Jim