Heavy Lift Drone build ( 40 inch prop ) U15 II 100 KV Motor

Hello everyone,

I am currently working on a heavy lift drone, and here are the specifications:

Motor: T motor U15 II 100 KV Motor
Propellers: T motor G40X13.2
Electronic Speed Controller (ESC): T motor Flame 180 A
Flight Control Board (FCB): Cube orange
After building the drone, I conducted an initial flight with the default parameters, and the drone took off without any issues. Then, I adjusted the initial parameters according to the prop size, ESC, etc. which included MOT_PWM_MIN, MAX, etc.

Next, I attempted to perform an autotune. I followed the sequence of autotuning the Roll axis first, then the Pitch axis, and finally the Yaw axis. After completing the Roll autotune, the gains were (P: 0.4, I: 0.4). Similarly, after the Pitch autotune, the gains were (P: 0.27, I: 0.27). The drone was flying well, and the attitudes were fine at this point. However, during the Yaw autotune, the drone started wobbling and eventually stabilized itself to the ground. This happened three times, with me shuffling the axes for the autotune, but each time the drone learned similar PID gains and became unstable right after the autotune.

As of now, I have kept the mot_thst_expo at 0.65 and have not made any adjustments. I would appreciate any valuable suggestions regarding this issue.


@xfacta Expecting your valuable suggestions on this

Set all battery voltage levels correctly and especially these:
use all the values from Initial Parameters

Also set
it’s your choice, but you dont want these copters with very big props getting away from you.

Set these
then retest and set your MOT_SPIN_ARM and MOT_SPIN_MIN

The problem was not resolved even though I performed a manual tune that improved it somewhat. However, I remain skeptical about whether the tuning will be effective if I am flying at a higher altitude than the one it was tuned for. For instance, if I tune the copter for 900 AMSL but end up flying at 4000 AMSL, I am unsure if the tuning will still be adequate, and whether it would be necessary to adjust it based on the specific weather conditions and altitude.

Have you got the latest .bin log? And a description of what you thought was wrong.

A change in altitude should be fine, I dont think there would be anything to change if the tuning is good in the first place.

Attaching last log of the test flight were the AUW is 105 kg.