Fixed Wing Sudden Nosedive in Stabilize Mode

Flight Testing & Log Analysis v1.13
1

I need help figuring out what went wrong in stabilized flight:
This plane was flying relieably in Stabilize mode, but after flying straight and level at full throttle for a few seconds it suddenly pitches down and nosedives into the ground.

Log: https://review.px4.io/plot_app?log=8f0fcc62-296b-468d-8520-53f2ed5a22d6

  • The V-tail still works fine after the crash, so I assume it is not a mechanical failure.
  • The controller setpoint is fine - my inputs were followed until the very last seconds of the flight
  • no failsafe or warning except one where the GPS message is invalid, but the GPS should not influence stabilized flight
  • The logged GPS position cuts off just before the nosedive
2

Seems like the pitch setpoint doesnt get tracked at the end, also the GPS had invalid data.

Perhaps the actuators & GPS suffered a power loss? Have you checked how the actuator (e.g. elevon) input translated to pitch movement during that last period?