I don't exactly know how the Kamov yaw system works but would assume that because the rotor systems are in line with each other the only way would be differential pitch which in turn causes differential torque and causes a yawing force on the fuselage.. .. .The Kaman helicopter use differential pitch as well as tipping one disk forward and the other aft during yawing turns. It helps pedal authority a little.. .. .It would be interesting to fly the Kamov rotor system or talk to someone that has. I wonder if it has the same "dwell zone" in the middle of the collective where there is very little if any pedal authority.