Technical Paper
Inclusion of the Rotor Speed Degree of Freedom for Substantial Increases In Advanced Rotorcraft Performance and Safety
2005-10-03
2005-01-3168
Fixed wing aircraft have six rigid degrees of freedom (3 translational and 3 rotational). Helicopters and autogyros became practical when Juan de la Cerva added the flapping degree and rotor disk tilt as an additional of freedom in the 1930s. This addition allowed rigid rotor helicopters to fly in forward flight without tilting over due to the unsymmetrical lift on the advancing and retreating blades. Rotor speed, while originally controlled manually by pilots in early helicopters and autogyros, is now held approximately constant by use of an engine governor. There have been several flight demonstrations over the past few years that have illustrated the potential of using the rotor speed degree of freedom for substantial increases in rotorcraft performance and safety.