Octaquad Plane with pixhawk 2.1 running patched firmware from Andrew Tridgell. started with default pids, but tried changing q yaw parameters, but I more than doubled q yaw P with no noticed effect. link to log here because here I’m limited on size of file.
It may not be yaw problem so sorry to clutter the site.
I found a mag issue. Looking at telemetry log Mission Planner shows something like EKF2 IMU1 mag ground anomaly re-setting yaw. I’m going to try just disabling the internal compass and see if that works.
I have solved this. It was caused by TX calibration issue. The EKF error seems to be a symptom rather than the cause.