Lose all servos on takeoff - Pixhawk


I've been using a Pixhawk for a while and I've never had this happen:

We calibrated the accel/compass and gyro when we arrived at the field

All sensors looked good after calibration.

On the ground all of the servos worked (tested throttle as well)

We performed 6 throttle run-ups, and sustained for 2x10sec runs. All surfaces works and the system was armed before takeoff. 

We launched the plane from our catapult (~2.5G's) and right after launch we lost all servo control. After the crash, we somehow regained servo control (we tested right after crashing without arming).

On approaching the plane, there were blue/red lights flashing, however the logs don't show a reboot. 

We've had this happen twice on the aircraft - once before upgrading to 3.5 and once after. 

In addition, after looking at the logs, it says that the plane pretty much started spinning right after launch (IMU went total haywire - just straight up spinning) however, would this cause an autopilot reset? 

I can upload the log files if people want, but they're pretty long (we go through a ton of tests before takeoff, so the logs are since then). 

I'm stumped - anyone have any ideas? 

Edit: I've added the logs and google earth KMZ if people want to see them: 


Edit: We've flown this plane multiple times before, with this autopilot (and the same setup, transmitter...etc). 

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    • Haha - we test our transmitter from a full runway length before launch. We've learned that from experience too.  :P

      We were on high power at launch - I checked it myself.

  • Hi Samuel,

    do you have a BEC in you setup (addition to the motor esc)?


    • Yes, we have a BEC that just powers the servos and the Pixhawk (it is set to the ok voltage for the Pixhawk, something around 5.5V). Also, the BEC is rated to the max Amps of all the servos (assuming each servo stalls). 

    • What's the overall voltage output of that BEC? From memory the Pixhawk operates at 5 volts, anything higher than that could lead to issues.

    • As per here, it can go up to 5.7: http://copter.ardupilot.com/wiki/common-powering-the-pixhawk/. We're at 5.5. 

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