An aircraft is provided and includes an airframe having main, pylon and tail sections, a rotor disposed at one of the pylon and tail sections and rotatable about a rotational axis to drive the airframe and a primary gearbox disposed within the main section of the airframe and a secondary gearbox disposed within one of the pylon and tail sections. The primary gearbox includes an outer housing rotationally fixed relative to the airframe and a driveshaft extending through the outer housing and coupled to the secondary gearbox to thereby drive rotation of the rotor relative to the airframe via the secondary gearbox. The aircraft further including a sensing system affixed to the outer housing and the driveshaft and configured to sense rotational characteristics of the driveshaft.

A method of data collection from a rotor system of an aircraft includes positioning a plurality of sensors at a plurality of locations of a rotating portion of the rotor system. One or more antennae are located at one or more rotationally fixed locations of the aircraft. Rotor system data is collected via the sensors and is wirelessly transmitted from the sensors to the antennae and is transferred from the antennae to a gateway where it is normalized and synchronized. In another embodiment, a data collection system for a rotor includes a plurality of sensors located at rotating locations of the rotor, the sensors configured to collect and wirelessly transmit rotor data. Antennae are located at a fixed location of the aircraft. The antennae are configured to send and receive data from the sensors. A gateway is connected to the antennae to normalize and synchronize the rotor data.

An improved rotorcraft blade tracking system and method is provided. The provided blade tracking system and method projects a focused beam of light with minimal variance in predetermined spectral characteristics at the ranges of distance suitable for rotorcraft blade tracking applications. The provided system and method detects a reflected beam of light that is associated with the projected focused beam of light. The provided system and method maintains eye safety, and performs consistently over a variety of environmental conditions.

A rotor blade configured to couple to a rotor assembly having an axis of rotation includes a blade radius R between the axis of rotation and an outboard end of the rotor blade when coupled to the rotor assembly. When an inboard end of the rotor blade is coupled to the rotor assembly at about x/R=0.10, between about 18 percent and about 22 percent of the total mass of the rotor blade is located between about x/R=0.88 and about x/R=0.93, x corresponding to a radial location of the rotor blade measured from the axis of rotation.

In an aspect, a system comprising a computing device. The computing device is configured to determine a drag minimization axis of a rotor connected to an aircraft. The rotor includes a first end and a second end. The rotor is configured to rotate about an axis. The computing device is further configured to determine a halting point of the rotor, wherein the halting point includes a drag minimization axis of the rotor. The computing device is configured to send a halting command to at least a magnetic element to halt the rotor, wherein the halting process is configured to stop a movement of the rotor and position the rotor in the halting point. The position of the rotor in the halting point includes the first end pointing in one direction of the drag minimization axis and the second end pointing in an opposite direction of the first end.

A method includes determining an angular rate of a rotorcraft based on a pilot input of the rotorcraft; determining an attitude reference for the rotorcraft based on the angular rate, the determining including determining an attitude difference from a trim attitude of the rotorcraft; determining a linear acceleration error for the rotorcraft; determining a trim attitude of the rotorcraft, wherein the trim attitude is based on the linear acceleration error; and summing the attitude difference and the trim attitude to generate the attitude reference; determining a flight command for the rotorcraft based on the attitude reference; and controlling flight control elements of the rotorcraft based on the flight command.

A rotor blade is provided that includes an airfoil extending spanwise from a base to a tip. The airfoil extends longitudinally (e.g., chordwise) from a leading edge to a trailing edge. The airfoil extends laterally between a first side and a second side. The airfoil includes a body and a weight. The body includes a plurality of body layers. Each of the body layers includes fiber reinforcement within a body thermoplastic matrix. The weight includes a weight layer embedded within the body. The weight layer includes metal powder within a weight thermoplastic matrix.

A tunable mass damper assembly is attachable to a rotor blade. The tunable mass damper assembly comprises a base configured to be attached to the rotor blade and a pendulum mass structure movably attached to the base and configured to move relative to the base in accordance with a rotational speed of the rotor blade about a rotor axis. The pendulum mass structure is configured to reduce vibratory forces of the rotor blade induced by a rotation of the rotor blade about the rotor axis. An entirety of the pendulum mass structure being configured to be contained within and enclosed by the rotor blade.

Rotor blades may be modified with field-installable profiles, or wedges towards the rear trailing end. The wedges may incorporate one or more porous sections to enhance fluid flow through the wedge, and thus reduce trailing edge noise and rotor vibrations when the rotors are in use. The use of porous materials on the trailing end of the blade and/or wedge reduces the intensity of high-frequency noise. A portion of the wedge may retain impermeable characteristics and be paired with a more porous section to minimize the boundary layer, and thus reduce noise. The wedges may be installed in the field, and easy removed, replaced, and/or applied manually to the rotor blade trailing edge. As the vehicle is used, the placement and choice of location and number of wedges applied to one or more rotor blades may be modified each time the vehicle rotor blade come to rest.

A rotor blade configured to couple to a rotor assembly having an axis of rotation includes a blade radius R between the axis of rotation and an outboard end of the rotor blade when coupled to the rotor assembly. When an inboard end of the rotor blade is coupled to the rotor assembly at about x/R=0.10, between about 18 percent and about 22 percent of the total mass of the rotor blade is located between about x/R=0.88 and about x/R=0.93, x corresponding to a radial location of the rotor blade measured from the axis of rotation.