I am trying to better understand the Yaw Controller of the Plane. Unfortunately, the documentation does not explain the Turn Coordination Calculation. In Git I found the following formula for it:
// @Param: 2SRV_RLL
// @DisplayName: Yaw coordination gain
// @Description: Gain to the yaw rate required to keep it consistent with the turn rate in a coordinated turn. Corrects for yaw tendencies after the turn is established. Increase yaw into the turn by raising. Increase yaw out of the turn by decreasing. Values outside of 0.9-1.1 range indicate airspeed calibration problems.
// @Range: 0.8 1.2
// @Increment: 0.05
// @User: Advanced
AP_GROUPINFO("2SRV_RLL", 3, AP_YawController, _K_FF, 1),