Torque compliant rotor - In flight auto-rotation - HL-1D
382 views · Published 17 August 2018 · 4:23 · Indexed 29 October 2026
Channel: RCmags · 2018 · Entertainment
This is an in-flight demonstration of the ability of a torque compliant rotor to enter and sustain an auto-rotation. Not only that, but of the mechanism's ability to allow for a easy transition between powered and unpowered flight while an aircraft is still in the air. The helicopter used in this video, the HL-1D, does not have a one way bearing connecting the rotor to the transmission and motor. Rather, the entire unit is connected at all times. While this is mechanically very simple, it has the drawback of increasing the friction felt by the rotor when it freewheels. As is seen in the video, this friction is strong enough that over time it can force the fuselage of the helicopter to rapidly spin unless a counter torque is applied. In this case, the tail rotor of the helicopter is unidirectional and cannot apply a reverse thrust to counter the torque induced by friction. It is only designed to adequately counter the reaction torque of the rotor when it is directly powered by a motor. Consequently, if left unconstrained, a powered rotor will force the fuselage to rotate in one direction (opposite to the rotation of the rotor) and an unpowered rotor will force rotation in the opposite direction (as the rotor "drags" the fuselage in the same direction as revolves in).
