In one embodiment, a rotor blade may comprise a blade body, a spar structure, and a blade nose. The blade body may comprise a skin, wherein the skin is configured to form an airfoil shape, and wherein the airfoil shape comprises an inboard end, an outboard end, a leading edge, and a trailing edge. The spar structure may comprise a first spar cap and a second spar cap, wherein the first spar cap is coupled to an upper portion of the skin, and wherein the second spar cap is coupled to a lower portion of the skin. The blade nose may comprise a cavity, wherein the cavity is configured to house a plurality of modular weights at a plurality of radial blade locations, wherein the plurality of radial blade locations comprises a range of locations between the inboard end and the outboard end.

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.

An example of a rotor-state determining method for a rotor system includes, by a flight control computer, collecting data from a first sensor positioned on a first component of the rotorcraft, wherein the first sensor is isolated from movement of a rotor blade, collecting data from a second sensor positioned on a second component of the rotor system, wherein the second sensor detects movement of the rotor blade, filtering the data collected by the first sensor to remove noise from the data collected by the first sensor, filtering the data collected by the second sensor to remove noise from the data collected by the second sensor, calculating a difference between the filtered first data and the filtered second data to determine a parameter of the rotor blade, and responsive to the motion of the rotor blade, taking a corrective action.

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 manufacturing a particulate-binder composite article including a mold defining a mold cavity, a first opening into the mold cavity, and a second opening into the mold cavity, a mass of a particulate material received in the mold cavity, a binder source in selective fluid communication with the mold cavity by way of the first opening, the binder source including a binder material, a first filter disposed across the first opening, the first filter being permeable to the binder material and substantially impermeable to the particulate material, and a second filter disposed across the second opening, the second filter being permeable to air and substantially impermeable to the particulate material.

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.

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.

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.

An aircraft is provided including an airframe, an extending tail, a counter-rotating, coaxial main rotor assembly having an upper rotor assembly and a lower rotor assembly, and a translational thrust system including a propeller positioned at the extending tail. The translational thrust system is configured to provide translational thrust to the airframe when the aircraft is in a non-autorotation state and to generate power when in an autorotation state. A gearbox interconnects the propeller and the main rotor assembly to drive the main rotor assembly and the translational thrust system in the non-autorotation state. When the aircraft is in autorotation, the power generated by the propeller drives rotation of the main rotor assembly via the gearbox.

A system for manufacturing a particulate-binder composite article including a mold defining a mold cavity, a first opening into the mold cavity, and a second opening into the mold cavity, a mass of a particulate material received in the mold cavity, a binder source in selective fluid communication with the mold cavity by way of the first opening, the binder source including a binder material, a first filter disposed across the first opening, the first filter being permeable to the binder material and substantially impermeable to the particulate material, and a second filter disposed across the second opening, the second filter being permeable to air and substantially impermeable to the particulate material.