1. Should we consider variable rotor speeds?;Prouty;Vertiflite,2004
2. An investigation of variable rotor RPM on performance and trim;Steiner,2008
3. Flight control design for rotorcraft with variable rotor speed;Horn,2008
4. Helicopter flight control with variable rotor speed and torque limiting;Guo,2009
5. Operational benefit of an optimal, widely variable speed rotor;DiOttavio,2010