I built a Hexcopter on S500 frame using Pixhawk 1 (Arducopter 3.4.6), Hobbypower 2212-920KV motors, and SimonK 30A ESC, ReadytoSky Ublox GPS, Trannis Radio with X8R reciever, and 5500mah Lipo 3S.
When the motors start everything is really smooth, as I up the throttle there seems to be no motor response until 50%-60% i.e. motors do not even accel. As soon as they start to Accel I get an instant Flip to left, no lift off just a fast flip-over on the ground.
I replaced a broken prop and went through individual motor tests again to verify motor rotation and proper prop (CW, CCW) on the correct motor, everything was as it should be. I tried again and go the exact same result.
Bin Logs are 2019-01-06-11-04-59 and 2019-06-11-35-30
There is a video there as well.