You are of course right, Chuck, that the disadvantges of the servo flap rotor for a conventional (recreational) gyro are
such that no one seriously seems to consider one.
Well, I beg to differ Juergen
....'cause in my opinion, I do seriously believe a servo-flap controlled rotor (through a swashplate or electric actuators) has several advantages over a tilting/gimbaled rotorhead.
Advantages:
(A). Small cyclic stick actuation control forces: On a gimbal-headed, 2-bladed rotor, try holding the cyclic with the thumb and forefinger, from the start of pre-rotation through flight and until the rotor stops turning.....it is possible if you have a super strong hand.
(B). Lower rotor vibrations: One couldn't slap on servo-flaps to a standard gyro-type rotorblade and expect it to work worth a hoot. A servo-flap controlled rotorblade must not be as rigid in torsion as is required by blades that are pitched at the root or by the rotorhead. Servo-flaps that are positioned aft of the blade trailing-edge, act as horizontal stabilizers for the rotorblade and help dampen out vibrations. These blades are also easier to adjust for tracking....it's like having big trim-tabs. These blades are also easier to balance, especially in the chord-wise direction. A rigid 3-bladed rotor will have less vibrations than a semi-rigid, 2-bladed rotor.
(C). Higher pre-rotation rpm due to less lift drag: The servo-flaps can keep the blade airfoil at zero lift during spin-up and then move to positively twist the blades when ready to fly. The blade root stays locked. Because these blades can twist both positive and negative degrees while in flight (like a helicopter), I believe the airfoil should be at or near symmetrical, like 0012. Once flying straight and level, the blades have a positive twist which is similar to a Dragon Wings blade, except the in-flight adjustable tip speed can be kept close to 400 fps for less parasitic blade drag.
(D). Due to the way these blades can be controlled and how the rotorhead is designed, the airframe follows this rotor system's every movement.....like preventing rollover right after landing. Jump take-off is also within reach.....
There are more advantages but I've run out of time.....
I like and respect what Kaman designed and I think servo-flaps have a place in the newer gyroplane's.
Here is an idea of what I'm going on about.....