1. 1) Prouty, R. W.: Should We Consider Variable Rotor Speeds? Vertiflite, 50 (2004), pp. 24–27.
2. 2) Steiner, J., Gandhi, F., and Yoshizaki, Y.: An Investigation of Variable Rotor RPM on Performance and Trim, The American Helicopter Society 64th Annual Forum, Montreal, Canada, April 29–May 1, 2008, pp. 697–705.
3. 3) DiOttavio, J. and Friedmann, D.: Operational Benefit of an Optimal, Widely Variable Speed Rotor, The American Helicopter Society 66th Annual Forum, Phoenix, USA, May 11–13, 2010, pp. 1865–1871.
4. 4) Mistry, M. and Gandhi, F.: Helicopter Performance Improvement with Variable Rotor Radius and RPM, J. Am. Helicopter Soc., 59 (2014), pp. 17–35.
5. 5) Bowen-Davies, G. M. and Chopra, I.: Aeromechanics of a Slowed Rotor, J. Am. Helicopter Soc., 60 (2015), pp. 1–13.