A rotor for a hover-capable aircraft is described that comprises: a drive mast; a hub operatively connected to the drive mast and rotatable about a first axis; and at least two blades hinged to the hub, via a rigid or elastically deformable connection, so as to be able to assume an attitude rotated about and/or translated along at least a second axis with respect to said hub; the aircraft further comprising sensor means configured to detect the attitude of at least one said blade with respect to the hub; the sensor means are configured to acquire an optical image associated with the attitude of the blade with respect to the hub.

A magnetorheological fluid clutch apparatus comprises an input rotor adapted to be coupled to a power input, the input rotor having a first set of at least one input shear surface, and a second set of at least one output shear surface. An output rotor is rotatably mounted about the input rotor for rotating about a common axis with the input rotor, the output rotor having a first set of at least one output shear surface, and a second set of at least one output shear surface, the first sets of the input rotor and the output rotor separated by at least a first annular space and forming a first transmission set, the second sets of the input rotor and the output rotor separated by at least a second annular space and forming a second transmission set. Magnetorheological fluid is in each of the annular spaces, the MR fluid configured to generate a variable amount of torque transmission between the sets of input rotor and output rotor when subjected to a magnetic field. A pair of electromagnets are configured to deliver a magnetic field through the MR fluid, the electromagnets configured to vary the strength of the magnetic field, whereby actuation of at least one of the pair of electromagnets results in torque transmission from the at least one input rotor to the output rotor.

A magnetorheological fluid clutch apparatus comprises an input rotor adapted to be coupled to a power input, the input rotor having a first set of at least one input shear surface, and a second set of at least one output shear surface. An output rotor is rotatably mounted about the input rotor for rotating about a common axis with the input rotor, the output rotor having a first set of at least one output shear surface, and a second set of at least one output shear surface, the first sets of the input rotor and the output rotor separated by at least a first annular space and forming a first transmission set, the second sets of the input rotor and the output rotor separated by at least a second annular space and forming a second transmission set. Magnetorheological fluid is in each of the annular spaces, the MR fluid configured to generate a variable amount of torque transmission between the sets of input rotor and output rotor when subjected to a magnetic field. A pair of electromagnets are configured to deliver a magnetic field through the MR fluid, the electromagnets configured to vary the strength of the magnetic field, whereby actuation of at least one of the pair of electromagnets results in torque transmission from the at least one input rotor to the output rotor.

A blade angle feedback assembly for an aircraft-bladed rotor and an aircraft-bladed rotor system are provided. The rotor is rotatable about a longitudinal axis and has an adjustable blade pitch angle. A feedback device is coupled to rotate with the rotor , the feedback device having a root surface having an edge. At least one position marker extends from the root surface and extends laterally beyond the edge. At least one sensor is mounted adjacent the feedback device and configured to detect a passage of the at least one position marker as the feedback device rotates about the longitudinal axis.

A blade angle feedback assembly for an aircraft-bladed rotor and an aircraft-bladed rotor system are provided. The rotor is rotatable about a longitudinal axis and has an adjustable blade pitch angle. A feedback device is coupled to rotate with the rotor , the feedback device having a root surface having an edge. At least one position marker extends from the root surface and extends laterally beyond the edge. At least one sensor is mounted adjacent the feedback device and configured to detect a passage of the at least one position marker as the feedback device rotates about the longitudinal axis.

A rotor assembly includes a rotor hub which rotates about a hub rotation axis and a blade connected to the rotor hub. The blade rotates with the rotor hub around the hub rotation axis, and the blade is configured to rotate around a pitch rotation axis of the blade to adjust a pitch of the blade. The rotor assembly includes a pitch horn having a first end rotatably connected to the blade. The pitch horn is configured to rotate with the blade around the pitch rotation axis of the blade to adjust the pitch of the blade, and the pitch horn is configured to rotate relative to the blade around a pitch horn pivot axis arranged at a non-parallel angle relative to the pitch rotation axis of the blade.

A rotor assembly includes a rotor hub which rotates about a hub rotation axis and a blade connected to the rotor hub. The blade rotates with the rotor hub around the hub rotation axis, and the blade is configured to rotate around a pitch rotation axis of the blade to adjust a pitch of the blade. The rotor assembly includes a pitch horn having a first end rotatably connected to the blade. The pitch horn is configured to rotate with the blade around the pitch rotation axis of the blade to adjust the pitch of the blade, and the pitch horn is configured to rotate relative to the blade around a pitch horn pivot axis arranged at a non-parallel angle relative to the pitch rotation axis of the blade.

A method of controlling a tail rotor system of a helicopter includes pivoting a swashplate of the tail rotor system about an axis passing through a diameter of the swashplate. Pivoting the swashplate causes a first linkage of a first pair of linkages coupled between the swashplate and a collective crosshead to move in a first direction and a second linkage of the first pair of linkages coupled between the swashplate and the collective crosshead to move in a second direction that is opposite the first direction. The movement of the first and second linkages causes a plane of rotation of a pair of rotors of the tail rotor system to cant relative to a centerline of a mast of the tail rotor system.

A method of controlling a tail rotor system of a helicopter includes pivoting a swashplate of the tail rotor system about an axis passing through a diameter of the swashplate. Pivoting the swashplate causes a first linkage of a first pair of linkages coupled between the swashplate and a collective crosshead to move in a first direction and a second linkage of the first pair of linkages coupled between the swashplate and the collective crosshead to move in a second direction that is opposite the first direction. The movement of the first and second linkages causes a plane of rotation of a pair of rotors of the tail rotor system to cant relative to a centerline of a mast of the tail rotor system.

An aircraft includes an airframe; an extending tail; a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; and a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe; wherein a ratio of (i) the hub separation between the hub of the upper rotor assembly and the hub of the lower rotor assembly to (ii) a radius of the upper rotor assembly is between about 0.1 and about 0.135.