Quadcopter Rotor Phasing for Minimization of Aircraft Vibratory Loads

Vibration reduction via individual rotor phasing is explored systematically on a 3.2kg quadcopter with stiff, variable pitch
rotors. Multi-rotor phase modes are defined and systematically examined in turn on both a cross- and plus configuration
quadcopter. 45deg of pitch phasing reduces the 2/rev vertical vibrations by 97% from the case where all
rotors are in-phase, from 0.13g to 0.004g, and 2/rev drag by 89.5% (from 0.06g to 0.0063g). 2/rev pitching moment
is also reduced by 17% for phase = 45deg, but cannot be reduced to zero for any FP. Roll and yaw phasing can also
reduce 2/rev vertical forces, but introduce significant roll vibration. Roll phasing also introduces a yaw moment, while
differential phasing adds a 2/rev side force. None of the three modes defined on a plus-type quadcopter reduce all of
the forces simultaneously.