Auto TakeOff Help

Hello everyone!
I am in need of help with UAV on auto takeoff.
My UAV is dropping a little bit before I let go of the bungee launche and start the engine. In some cases, even touching the ground before ascending.
Can anyone help me understand what could be wrong?
On the link below are: video and flight log, as well as the complete parameters of my UAV. Ardupilot 4.0.9.