Auto takeoff crash

Hi everyone,
We have a plane with a low kV motor in terms of efficiency. Therefore, it loses a little altitude during takeoff. However, there is no problem in manual takeoffs.

We wanted to test our plane by making adjustments to take off autonomously. However, the plane lost altitude and hit the ground at the back. When I compare the logs of autonomous and manual flights, I set the pitch value (Servo 2) to maximum in manual flights, but it reached its maximum in autonomous flight just when it started to fall. We want to increase the c2 channel. What parameters should we change to solve this?

Manual log: 31.02.383 (14:29:26 UTC)

Auto log: 26.03.666 (14:05:41 UTC)

Manual and auto flight logs

The trim value of servo 2 (~1740) indicates that you have a serious elevator trimming / center-of-gravity issue.

If the CG is correct, mechanically trim the elevator up until auto-trim feature comes up with a trim value close to 1500!

The plane is crashing in auto takeoff because the I-Gain cannot trim out the plane fast enough and may even saturate before reaching trim-neutral.

Another thing that I see in your logs.
Tell the guy who throws the plane, to throw it horizontally, not with 20-30deg pitch up.
Apparently you’re behind the power curve at this moment which is another issue that fails the takeoff.

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Thank you for your answer. I will check the CoG and servo trim. If I change the mechanical trim, should I autotune again?

Yes, it takes multiple iterations to get everything right.
You can do auto-tune and when flying straight for a couple of seconds, auto-trim feature (which has nothing to do with auto-tune) will save the Servo2 Output which it needs for flying level to SERVO2_TRIM occasionally.
Auto-trim is limited to 20% of the pwm range and 1740 indicates that it sits on the 20% edge and wants to go further in that direction to trim out the pitch axis.

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