1. S. Ashok, B. Wade, D.P. Schrage, Variable speed transmission using planetary gear system for high speed rotorcraft application, in: Proceedings of the 66th Annual Forum of the American Helicopter Society, Phoenix, AZ, May 11–13, 2010.
2. A. Bagai, Aerodynamic design of the X2 Technology DemonstratorTM main rotor blade, in: Proceedings of the 64th Annual Forum of the American Helicopter Society, Montreal, Canada, April 29–May 1, 2008.
3. R. Blackwell, T. Millott, Dynamics design of the Sikorsky X2 TechnologyTM demonstrator aircraft, in: Proceedings of the 64th Annual Forum of the American Helicopter Society, Montreal, Canada, April 29–May 1, 2008.
4. J. DiOttavio, D. Friedmann, Operational benefits of an optimal, widely variable speed rotor, in: Proceedings of the 66th Annual Forum of the American Helicopter Society, Phoenix, AZ, May 11–13, 2010.
5. W. Guo, J.F. Horn, Helicopter flight control with variable rotor speed and torque limiting, in: Proceedings of the 65th Annual Forum of the American Helicopter Society, Grapevine, TX, May 27–29, 2009.