I have just taken my newly built 3DR Arducopter (APM) out for her maiden flight. Essentially she seems underpowered.
At first she would lift ok and then slowly drop to the ground. Then after a minute or so of repeating this, eventually the motors got slower and slower until they wouldn't even spin at max throttle.
At first I obviously though that the battery had discharged, until I plugged it in to the charger to see that it was actually at over 9v.
Does anyone have any ideas please?