I'm using Sunnysky 4108 480kv motors with RCTimer 30 amp SimonK ESC's.  The reason for the motor choice is it allows me to run bigger props.  My problem is motor stutter when running 15 x 5 carbon propellers. I set the quad up with 12 x 4.5 props…

I'm flying a quad using 4108 480kv motors with 15 x5.5 props, APM 2.5, Arducopter 3.0 and mission planner 1.2.60.  The quad was very stable with 12 x 4.5 props but with the 15s not so much.  It acts twitchy at hover and has a wicked oscillation on…