In Radio-controlled helicopters
, Cyclic/collective pitch mixing (CCPM)
is used to reduce mechanical complexity and increase precision of the control of the helicopter's swashplate
How CCPM mechanical mixing works
Conventional model helicopters use three independent servos
to manipulate the swashplate. One is used to tilt the swashplate forward and aft
longitudinal), varying the pitch
. Another is used to tilt the swashplate left and right (Cyclic
lateral), varying the roll
. The third servo raises and lowers the entire swashplate, varying the collective
. However, an intermediate mechanical mixing system must be used to transfer the control inputs from the servos to the swashplate. This requires an elaborate system of control rods and levers, and often contains many ball bearings.
How CCPM electronic mixing works
To reduce the mechanical complexity of the helicopter, a CCPM system mixes the control inputs using software (usually running on the transmitter
) and typically uses three interdependent servos to control the swashplate, with three linkages arranged around the swashplate at 120° intervals. In addition to lower mechanical complexity, the interdependent servos share the workload.