Auto TakeOff - Different behaviour within the same flight

I’m currently playing around with auto takeoff a little bit and so far mostly it’s working quite good. However, sometimes I see some behaviour that is unexpected, or at least it is to me, where the plane drifts away from its straight heading. I even see this happening in the same flight when doing Takeoff - RTL - manual landing - Takeoff - RTL - manual landing. So the parameters/settings/mission are all the same, the weather conditions are equal and the flight location is the same. I’ve added two images from the KMZ file. Again, these are from one log/flight.

This one works as expected. I switch to auto mode (red line), it flies in a straight line, and when reaching the desired altitude it switches to RTL mode as I set up in Mission Planner.

This one acts differently. Again, switching to auto mode (purple), it drifts to the left and eventually I switch to FBWA mode to steer it back.

Now, my assumption is that the heading when at low altitude and speed is controlled by the attitude data. My second assumption is that at or immediately before switching to AUTO mode the plane stores its current heading/yaw and sets that as the target heading for a takeoff routine. Are these assumptions correct?

With these assumptions in mind I went on to look at the flight logs. The yaw at time of switching to AUTO mode was definitely not the same as it was at the end of AUTO mode (just before switching back to manual/FBWA control).

Am I simply misunderstanding the way the TAKEOFF routine works? Or is this a specific parameter with regards to steering that I could tune to improve the consistency in keeping its heading? Hoping you guys can advice me on this. Thanks.

I bet it’s your yaw damper settings. Takeoff mode is trying to hold wings level and doesn’t care much about ground track/heading. When you are at high angles of attack with a single prop, you may have a right or left hand turning tendency. It appears left according to your second picture. The yaw damper/integrator should help you maintain straighter lines and more coordinated takeoff.

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