I just completed a CX20 rebuild to a Alien 450 frame. Installed Arducopter 2.8 FC, Sunnysky 2212 980k motors with DJI standard 9" props and a 5100 lipo batterh. It will not lift off!! I have calibrated everything through MP and the motors and props are installed correctly.
When I arm the motors and increase throttle the RPM's increase but not in a linear fashion. RPM's remain constant at full throttle and only by moving throttle left or right do they reach full RPM;s. It is the same when throttling down. The quad appears to be struggling to lift off. Total weight is 48oz (1360g). I would think these motors could handle that amount of weight.
Would increasing prop size to 10-12" help or are the stock ESC's the problem?