Originally Posted by edi
What is this approach?
The kaman helicopters use a swashplate for cyclic, but instead of letting the swashplate twist the blades on feathering bearings, the linkage moves a servo flap at about 75% of the blade radius. This makes the flexible blade twist and change it's pitch for both cyclic and collective.
It depends on the blades being torsionally flexible.
Put "Kaman Servo Flap" in google to see lots of info.
Ari wanted to replace the swashplate and linkage with a servo and electronics to drive the servo flap electronically, a technique that has been studied or perhaps tried on full sized aircraft. But the response of the servo has to be fast, probably 10 times faster than the time it takes the blade to go around. For a full sized aircraft this might be a long time at a few hundred RPM, but for a model at 1000 RPM the servo would have to be extremely fast, much faster than any currently available servo. Also model blades are probably too rigid for this approach. So the approach is possible but not practical right now.