Crash due to ESC in fire

[Riccardo]

Hi,

Please help finding the issue. Some more informations:

Tarot X6 airframe
Tarot 5008 motors
T-Motor S45A ESCs
Pixhawk 2.1 with PX4 flight stack

Take off in Position control mode. I was hovering a few meters above the ground, testing pitch and roll reactions to tune the PIDs.

The ESC got in fire while flying, the prop slowed down and the copter started to lose altitude while yawing. I had to find a good place to land as soft as possible, fortunately it seems I had just the ESC burned and its motor is a bit harder to turn.

Here you are the link to the LOG: http://logs.px4.io/plot_app?log=c24c48db-6768-4a33-9e0e-c75fcc828bad

[nkhoit]

How is your FC mounted?
It kind of looks like your vibrations are way too high.
It fed back into the feedback control loops and blew up your ESCs I'm guessing.

[Riccardo]

Hello,

The FC was mounted with a lot of dumping: soft rubber cylinders below and anti vibration pads between the cylinders and the FC. Furthermore the Pixhawk 2.1 should be internally dampened. Is it possible that the FC was too much dampened?

[nkhoit]

yeah it's possible. If you're using the Pixhawk 2.1 you don't need any external dampening because the IMU is already dampened. So I'd just try that.
If it's still bad, I'd start tuning the PID controller a little bit.
All else fails, get a bigger ESC.

When you took off, was it apparent that the controller was poorly tuned or it flew fine until the ESC blew up?

[Riccardo]

It always flew like shit since I installed the 2.1 with PX4. The Pixhawk 1 with APM and no tuning at all was solid as a rock on exactly the same frame.

[nkhoit]

It's likely a combination of the two really. Just hard mount the pixhawk 2.1 to your frame and then tune the MC PID gains for your airframe. It's likely the default ones just aren't that good for your airframe.

[Riccardo]

Ok, thank you very much for the advice. I will work on it.