Large 10KG payload Drone crash on take off! Please help

Hello All!
I’m working on a large agricultural drone that I purchased during an overseas trip at an agricultural convention. The Quadcopter came with a DJI WooKong-m flight controller so after a few flights, I immediately swapped it out with a pixhawk due to the DJI not being flexible for adding accessories laser altimeter and RTK GPS.
Drone info:
-full carbon fiber body
-12-15 Amp motors - All info is Chinese so unfortunately no more info that I could provide
-100A Platinum pro ESC’s
-2 x 22.2 2600 Mah Lipo’s
-Pixhawk FC - connected to power mudule #1

    -Jdrones long range radio’s ( telemetry port) - connected to power module # 2
    -X8R 2.4 ghz radio (rc)
    -2 x power modules (…)
    (all test flights with RC controller & no payload))
    I flew the quad after setting all of the recommended pixhawk parameters and calibrations. I tested some short take off and landings to make sure I could control the quad in Stabilize mode and all seemed ok (RC controller only). I added the Jdrones telemetry radios so I could have more info displayed during my next planned test flight. During this next test flight (stabilize mode) the drone went into a crazy death wobble and flipped over during take off. Lucky the few second flight was at a low altitude so only the carbon fiber props were damaged and the top cover of the drone. Please note - During this crash I was only using the throttle control to take off.
    I’m a newbie when it comes to the pixhawk and analyzing the flight data but I noticed the compass info go way off during acceleration of the motors so possibly interference causing the problem?? If this is the case I’m not sure why the first few tests were o.k. This may be some helpful info but after the first test i attempted to re calibrate the compass and had issues with MP freezing during the calibration. Eventually I got it to work but compass # 2 had some large Z vale of -460 but from what I read it uses compass 1. After the crash its now giving a prearm error of inconsistent compasses. The pixhawk also wont always power up with battery power now but after multiple tries it will work. Any help would be appreciated. Thanks!
    Auto log analyzer
    Log File C:/Program Files (x86)/Mission Planner/logs/QUADROTOR/1/15 2016-08-27 8-25-08 AM.bin.log
    Size (kb) 543.43359375
    No of lines 7104
    Duration 0:00:27
    Vehicletype ArduCopter
    Firmware Version V3.3.3
    Firmware Hash acf2e10c
    Hardware Type
    Free Mem 0
    Skipped Lines 0
    Test: Autotune = NA -
    Test: Balance/Twist = NA -
    Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 3.20m
    Test: Compass = FAIL - Large change in mag_field (70.30%)
    Max mag field length (853.22) > recommended (550.00)
    Test: Dupe Log Data = GOOD -
    Test: Empty = GOOD -
    Test: Event/Failsafe = GOOD -
    Test: GPS = GOOD -
    Test: IMU Mismatch = GOOD - (Mismatch: 0.10, WARN: 0.75, FAIL: 1.50)
    Test: Parameters = GOOD -
    Test: PM = NA -
    Test: Pitch/Roll = NA -
    Test: Thrust = NA -
    Test: VCC = GOOD -
    Hopefully i have provided enough info… here is the log file if anyone in interested in helping find the source…15 2016-08-27 8-25-08 AM.bin (264 KB)

Do you have some pictures of your copter? What about prop and motor size? It looks like you didn’t have quite enough thrust to take off. You’d need a longer log file to really check.

Thanks for the reply.

The props are 27" but unsure of the motors due to lack of info from supplier. Please note that I have flown this a few times with and without a 10KG payload but with the DJI controller and it flew great.

I’ve built a few large multicopters, and what I’ve found is adding weight helps with the tuning. The stock PIDs most likely won’t work, and you will need to tune the copter to perform better. The compass data is a different issue, but first let’s work on the tuning of the copter.