A propulsor hub is provided and includes a casing including an inner annular part and blade-connection parts extending outwardly from the inner annular part, a liner having inner and outer opposed radial ends, the liner being disposed about a corresponding one of the blade-connection parts with the inner radial end thereof at a distance from the inner annular part and a weighted element securely disposed about the corresponding one of the blade-connection parts to abut the outer radial end of the liner.

A weight system for a rotor blade includes a weight box open in an outboard direction, a weight guide rod connected to the weight box, the weight guide rod extending in a spanwise direction through an interior of the weight box, and a span balance weight disposed within the weight box, the span balance weight being captured between the weight guide rod and the weight box.

A method of forming a balanced rotor blade assembly includes measuring a weight of a plurality of sub-components of the rotor blade assembly excluding a core. A configuration of a core of the rotor blade assembly is determined. In combination, the core and the plurality of sub-components achieve a target weight distribution and moment. The core is then fabricated and assembled with the plurality of sub-components to form a rotor blade sub-assembly.

A rotor-hub flap-measurement system includes a rotor hub operable to flap relative to a main-rotor axis, a flap-linkage arm, a first end of the flap-linkage arm rotatably coupled to the rotor hub, the flap-linkage arm responsive to flapping of the rotor hub, and a magneto-resistive sensor system rotatably coupled to a second end of the flap-linkage arm and responsive to movement of the flap-linkage arm.

A multi-blade rotor of a rotary wing aircraft, the multi-blade rotor comprising at least one rotor blade that defines a pitch axis and that is provided with an associated pitch-control lever that is operatively coupled to a pitch link rod, the pitch link rod defining a longitudinal axis, wherein the associated pitch-control lever comprises an accommodation that is located on the longitudinal axis of the pitch link rod at a predetermined distance from the pitch axis of the at least one rotor blade, the pitch link rod being operatively coupled to the associated pitch-control lever at the accommodation of the associated pitch-control lever, wherein the predetermined distance is adjustable in order to enable adjustment of track and balance of the multi-blade rotor.

Tracker systems are disclosed, the system mountable on a device having one or more rotary component, comprising: an optical tracker having circuitry that causes the optical tracker to receive and filter optical signals including UV, visible, and infrared wavelengths so as to be more sensitive to UV wavelengths than the visible and infrared wavelengths. The optical tracker having circuitry transmitting data indicative of a distance; and one or more computer processor that utilizes the optical tracker determined distance to determine track error of the one or more rotary component of the device, and transmits data indicative of the track error.

A method of assembling a rotor blade includes determining first spanwise and chordwise moments of a first component of the blade and comparing the first spanwise and chordwise moments to respective target first spanwise and chordwise moments. The first spanwise and/or chordwise moment(s) of the first component is/are adjusted based upon corresponding results of the comparison to provide balancing of the first component. Second spanwise and chordwise moments of a second component of the blade are determined and compared to respective target second spanwise and chordwise moments. The second spanwise and/or chordwise moment(s) of the second component is/are adjusted based upon corresponding results of the comparison to provide balancing of the second component. The balanced first and second components are assembled to each other so that target spanwise and chordwise moments of the blade are met.

Technology for achieving the behavior and benefits of traditional cyclic control in one rotor may be implemented with a simple under-actuated passive mechanism. An air vehicle employing the disclosed technology maintains lifting thrust by regulating the average rotor speed and generates control moments through coordinated pulsing of the motor torque. Rapid pulsing of the motor torque induces oscillations in propeller angle of attack, and so causes cyclic control without requiring the traditional auxiliary actuators and linkages. The MAV propulsion system is capable of using a minimum number of actuators in dual roles of thrust and moment objectives.

A method of tip clearance estimation for a rotor blade is provided. The method includes measuring blade deflection of the rotor blade, generating a harmonic function for the rotor blade from the measured blade deflection, predicting tip displacement of the rotor blade using the generated harmonic function and adjusting a position of the rotor blade according to the predicted tip displacement.

A system for monitoring movements of rotor blades attached by flapping hinges to a central head or hub of a helicopter. At least one sensor is arranged to continuously measure vertical angular movement of a rotor blade and/or the flapping hinge. Also a method for monitoring movements of rotor blades attached by flapping hinges to a central head or hub of a helicopter.