I found out my RC controller had a few trims on… I turned them off and flew again:
2017-11-29 09-54-47.bin (3.5 MB)
Mid throttle was around 0,27… still below 30%.
Also, I didnt find the THR_MID parameter shown here: Setting Hover Throttle — Copter documentation
What is the correct name of the parameter I should change?