I have been wondering about this problem since i start to use APM about a year ago. After changing different airframe and motors, the behavior doesn't seems to improve. I check with a local friend who also encounter the behavior.
Behavior: Tilting left if throttle increment is a bit fast. If throttle increment is slow, lift off is okay.
So, I decided to log and video the behavior. Hope anyone who encounter the same problem can confirms it. Log is as attached and video link follows:
ACM 2.0.54 Y6
Thank you all, in advance.
Haha.... just saw the latest post by Jason on ACM 2.0.55. Might solve the behavior problem.
The thrust output curve (thrust / prop. speed) is very unlinear, and at low prop speed less steep. Maybe due to manufacturers variations in propeller or motor characteristics your right pair responds faster at spool up. Then when trying to compensate,the left motors still work in the lower more flat curve, and thus dont respond with the authority needed to catch up with its right hand brother?
This theory could be tried by swapping left and right drive packs with each other (motors, props, esc), and check if the behaviour is reversed.
But I understand if you don´t feel like messing with that ;)
Prop and motor are obviously the first thing you'd suspect. After that, perhaps a mechanical misalignment of the arms, or a problem with the mounting of the IMU.
But if it's persistent from airframe to airframe, perhaps something with the controller's default at-rest roll setting could be the culprit?
Thank you all for your kind replies. Cheers