A coaxial rotor system includes a center mast non-rotatably disposed at and extending from a helicopter. A rotation axis extends along the center mast. An inner mast is disposed along the center mast and is rotatable about the rotation axis in a first direction. A portion of the inner mast extends above an end of the center mast. An outer mast circumscribes the center mast and is rotatable about the rotation axis in an opposite second direction. The center mast extends above an end of the outer mast. An upper rotor blade assembly is rotatable with the inner mast. A lower rotor blade assembly is rotatable with the outer mast. A control system disposed at the center mast between the upper and lower rotor blade assemblies is operable to adjust pitch of a plurality of upper rotor blades and to adjust pitch of a plurality of lower rotor blades.

A rotary blade aircraft includes an airframe, a rotor shaft driven about a rotor axis, and a plurality of rotor blades driven by the rotor shaft about the rotor axis. The rotary blade aircraft includes a swashplate assembly coupled to the plurality of rotor blades. The swashplate assembly is operable to move the plurality of rotor blades about a respective longitudinal axis. The rotary blade aircraft includes a hydraulic control servo coupled between the airframe and the swashplate assembly. The hydraulic control servo is operable to move the swashplate assembly relative to the rotor axis. The rotary blade aircraft includes a harmonic control actuator coupled between the airframe and the swashplate assembly. The harmonic control actuator is operable independently relative to the hydraulic control servo to move the swashplate assembly relative to the rotor axis to reduce vibration at selected frequencies in the airframe.

A rotary blade aircraft includes an airframe, a rotor shaft driven about a rotor axis, and a plurality of rotor blades driven by the rotor shaft about the rotor axis. The rotary blade aircraft includes a swashplate assembly coupled to the plurality of rotor blades. The swashplate assembly is operable to move the plurality of rotor blades about a respective longitudinal axis. The rotary blade aircraft includes a hydraulic control servo coupled between the airframe and the swashplate assembly. The hydraulic control servo is operable to move the swashplate assembly relative to the rotor axis. The rotary blade aircraft includes a harmonic control actuator coupled between the airframe and the swashplate assembly. The harmonic control actuator is operable independently relative to the hydraulic control servo to move the swashplate assembly relative to the rotor axis to reduce vibration at selected frequencies in the airframe.

The present application discloses a three-steering gear direct-drive coaxial rotor system and a control strategy, and belongs to the technical field of helicopter structures. The system includes an upper rotor power module, an upper rotor assembly, an upper tilting mechanism, a driving steering gear group assembly, a lower tilting mechanism, a lower rotor assembly, a lower rotor power module, an upper fixing mast, and a lower fixing mast. According to the present application, three steering gears directly drives an upper-layer swashplate and a lower-layer swashplate, to make cyclic pitch and add-subtract collective pitch on rotors. The synchronous tilting mechanism of the present application provides a flexible design solution for the characteristic of cyclic pitch phase angle offset of the rotors gear.

The present application discloses a three-steering gear direct-drive coaxial rotor system and a control strategy, and belongs to the technical field of helicopter structures. The system includes an upper rotor power module, an upper rotor assembly, an upper tilting mechanism, a driving steering gear group assembly, a lower tilting mechanism, a lower rotor assembly, a lower rotor power module, an upper fixing mast, and a lower fixing mast. According to the present application, three steering gears directly drives an upper-layer swashplate and a lower-layer swashplate, to make cyclic pitch and add-subtract collective pitch on rotors. The synchronous tilting mechanism of the present application provides a flexible design solution for the characteristic of cyclic pitch phase angle offset of the rotors gear.

A control system for a multi-rotor aircraft is described that results in lower operating noise. Allowing blades to flap during flight reduces aerodynamic interference as blades pass by other aircraft components, such as wings or the fuselage. Pitch links coupled to a rotational swashplate can be used to allow flapping during flight. The swashplates can allow the canting of the rotors to change a rotational or out-of-plane angle of the blades to decrease noise.

A control system for a multi-rotor aircraft is described that results in lower operating noise. Allowing blades to flap during flight reduces aerodynamic interference as blades pass by other aircraft components, such as wings or the fuselage. Pitch links coupled to a rotational swashplate can be used to allow flapping during flight. The swashplates can allow the canting of the rotors to change a rotational or out-of-plane angle of the blades to decrease noise.

A light helicopter typically for 5 occupants is disclosed which achieves a hitherto unprecedented combination of range, speed and payload by adopting a novel approach to construction and positioning of components which affect overall aerodynamics in forward flight at speeds in excess of 70 metres per second and mass distribution and management of centre of gravity as fuel is consumed, load bearing strength and drag.

A light helicopter typically for 5 occupants is disclosed which achieves a hitherto unprecedented combination of range, speed and payload by adopting a novel approach to construction and positioning of components which affect overall aerodynamics in forward flight at speeds in excess of 70 metres per second and mass distribution and management of centre of gravity as fuel is consumed, load bearing strength and drag.

A rotor assembly includes a hub assembly and a shaft assembly. The hub assembly includes a hub and a first coupling, and the shaft assembly may be coupled to the hub assembly with a second coupling. The second coupling may be configured to facilitate rotation of the hub relative to a shaft of the shaft assembly. A rotor blade may be coupled to the hub assembly with a third coupling and be configured to rotate with the shaft. The first coupling may be configured to couple the hub to an actuator and transmit movements of the actuator to the hub to facilitate cyclic pitch control of the rotor blade. The rotor shaft may include arms and the hub may include a body coupled to the rotor blade by the third coupling and pairs of extensions that extend from a surface of the body to receive the arms.