I am testing a quadcopter frame Tarot 650 Sport (motors Trarot 4114 with T-Motor 1555 blades) with a Pixhawk 4. I have a little problem during the landing. Some seconds before the automatic disarmed, the motors give an acceleration unbalanced at the back. The propellers give a short push up, I affraid by a reversal of the drone. Have you somes ideas about this case ?