Abstract: A vibration attenuator for a rotor of an aircraft has a first ring with an eccentric weight, a coaxial second ring with an eccentric weight, and a central ring coaxial with the first and second rings and located therebetween. A first post extends from the first ring toward the central ring and is received in a first arcuate groove formed on the central ring, whereas a second post extends from the second ring toward the central ring and is received in a second groove formed on the central ring. A motor is configured for driving the central ring in rotation about the axis relative to the motor. The grooves are equal in length, and a center of the first groove is located on an opposite side from a center of the second groove. Rotation of the central ring by the motor causes rotation of the first and second rings.

Abstract: An aircraft that includes a fuselage, an electric motor driven propulsion system, and a fuel cell system configured to provide electricity to the electric motor. The fuel cell system includes a fuel cell, a hydrogen tank, an oxygen tank, an air channel, and a cathode switch. The cathode switch being configured to convert between an air mode, wherein the fuel cell operates utilizing air from the air channel, and an oxygen mode, wherein the fuel cell operates utilizing oxygen from the oxygen tank.

Abstract: A pylon conversion actuator, for use in tiltrotor aircraft, that converts the tiltrotor between hover flight mode and forward flight mode. Pylon conversion actuator selectively retracts and extends between a retracted position to an extended position. Pylon conversion actuator includes an extendable arm, a motor, and an actuator platform.

Abstract: A method of evaluating fatigue damage of a rotor mast. The method includes performing an x-ray diffraction (“XRD”) inspection of the rotor mast, assessing fatigue damage sustained by the rotor mast based on results of the XRD inspection, and determining whether the rotor mast is suitable for continued use based on the assessed fatigue damage.

Abstract: A hierarchical integrated trust assessment system features nested subsystems. Each subsystem utilizes a trust module for validating input data to the subsystem, validating output data from the subsystem, and validating the operation of the subsystem itself. The trust module verifies the format, the authenticity, the content of the inputs to the subsystem. The scope of each trust module is minimized to the associated subsystem. Minimizing the scope of the trust module results in increased reliability of the trust module's decisions.

Abstract: An example of a guard for a power tool includes a body that defines an interior space configured to receive the power tool. The body is configured to cover at least a moving portion of the power tool. The body includes an aperture formed through a bottom face of the body and a fastener configured to pass through the aperture and secure the guard to the power tool.

Abstract: An exemplary tiltrotor aircraft with a hybrid drive system includes a first propulsion system having a first engine and a first supplemental driver operably coupled to a first proprotor that is operable between a helicopter mode and an airplane mode and a second propulsion system having a second engine and a second supplemental driver operably coupled to a second proprotor that is operable between a helicopter mode and an airplane mode.

Abstract: A clutch that has a synchronizer for matching a rotational velocity of a drive input with a rotational velocity of a driven output prior to engagement of a locking mechanism.

Abstract: An exemplary integrated battery cargo platform includes a housing having an exterior surface and a structural strength to support cargo for transit on a top surface, a battery enclosed in the housing with power contacts exposed at the exterior surface.

Abstract: A test apparatus includes a first grip, a second grip movable relative to the first grip, a test specimen disposed to provide a load path between the first grip and the second grip, and a test chamber disposed to both substantially envelope the test specimen and move with one of the first grip and the second grip. The test chamber does not contact the test specimen. Another test apparatus includes, a first grip, a second grip movable relative to the first grip, a test specimen disposed to provide a load path between the first grip and the second grip, a first test chamber disposed to both substantially envelope the test specimen and move with one of the first grip and the second grip, and a second test chamber disposed to both substantially envelope both the test specimen and the first test chamber.

Abstract: In an embodiment, an aircraft includes first and second wings. The aircraft also includes a plurality of propulsion assemblies, the plurality of propulsion assemblies including a propulsion assembly connected to each end of each of the first and second wings. The aircraft also includes first and second vertical supports disposed between the first and second wings. The aircraft also includes a storage pod disposed between the first and second vertical supports. The storage pod includes a nose portion that extends forward of the plurality of propulsion assemblies. The nose portion includes at least one radar and at least one camera. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

Abstract: An exemplary ducted fan includes a duct having a central longitudinal axis, a rotor hub and stator hub extending along the central longitudinal axis, rotor blades extending from the rotor hub, each of the rotor blades operable to rotate about its own pitch-change axis, the pitch-change axes lying in a rotor plane that is generally perpendicular to the central longitudinal axis, each of the rotor blades having a rotor trailing edge and a rotor chord length, stators extending from the stator hub to an interior surface of the duct, each of the stators having a stator leading edge and a stator thickness, and a first separation between the rotor plane and the stator leading edge of not less than approximately 1.5 times the stator thickness.

Abstract: One example of a mount for a rotorcraft comprises a structural support member, a bracket, and an elastomer. The bracket is configured to attach to a component of the rotorcraft. The component of the rotorcraft produces vibrations at a first frequency. The structural support member configured to transfer a weight of the component of a rotorcraft to an airframe of the rotorcraft. A rotor system of the aircraft vibrates the airframe of the rotorcraft at a second frequency. The elastomer is located between a structural support member and a bracket. The elastomer is configured to attenuate noise caused by the vibrations at the first frequency by isolating the vibrations at the first frequency from reaching the airframe of the rotorcraft while the airframe vibrates at the second frequency.

Abstract: An aircraft landing gear assembly has a longitudinally elongated frame coupled to a lower portion of a fuselage of an aircraft, the frame being capable of supporting at least a portion of the weight of the aircraft. A fairing encloses substantially all of the frame. An optional integrated step can be carried by the frame, and a longitudinally elongated aperture would be formed in the fairing adjacent the step. The step allows a user to place a foot into the aperture and onto the step. An optional door can cover the aperture, and an optional secondary step can be carried by the door.

Abstract: In an embodiment, an aircraft includes an airframe and a first propulsion assembly coupled to the airframe. The first propulsion assembly includes a first rotor hub and a first plurality of rotor blades non-uniformly spaced about the first rotor hub and operable to rotate in a rotor plane with the first rotor hub. The aircraft also includes a second propulsion assembly coupled to the airframe. The second propulsion assembly includes a second rotor hub and a second plurality of rotor blades non-uniformly spaced about the second rotor hub and operable to rotate in a rotor plane with the second rotor hub.

Abstract: An electrically distributed yaw control system for a helicopter having a tailboom includes a plurality of tail rotors rotatably coupled to the tailboom and a flight control computer implementing a tail rotor balancing module. The tail rotor balancing module includes a tail rotor balancing monitoring module configured to monitor one or more parameters of the helicopter and identify a first set of one or more tail rotors in the plurality of tail rotors based on the one or more parameters. The tail rotor balancing module also includes a tail rotor balancing command module configured to modify one or more operating parameters of the first set of tail rotors.

Abstract: In an embodiment, a method includes receiving flight data related to an aircraft that includes an engine installed therein. The flight data includes values of an engine parameter. The method also includes determining values of a measured installation delta for the engine based, at least in part, on the flight data. The method also includes determining values of a measured power parameter for the engine based, at least in part, on the flight data. The method also includes generating a mathematical model of a plurality of installation deltas for the engine as a function of the engine parameter, where the plurality of installation deltas include the measured installation delta and an unmeasured installation delta. The method also includes validating the mathematical model based, at least in part, on the values of the measured installation delta. The method also includes generating a performance profile of the engine.

Abstract: A yaw control system for a helicopter having a tailboom includes one or more tail rotors rotatably coupled to the tailboom and a quiet mode controller. The quiet mode controller includes a noise monitoring module configured to monitor one or more flight parameters of the helicopter and a quiet mode command module configured to selectively switch the one or more tail rotors to a quiet mode based on the one or more flight parameters. The quiet mode command module is also configured to modify one or more operating parameters of the one or more tail rotors in the quiet mode to reduce noise emitted by the helicopter.

Abstract: A yaw control system for a helicopter having an airframe that includes a tailboom includes one or more tail rotors rotatably coupled to the tailboom and a flight control computer implementing an airframe protection module. The airframe protection module includes an airframe protection monitoring module configured to monitor one or more flight parameters of the helicopter and an airframe protection command module configured to modify one or more operating parameters of the one or more tail rotors based on the one or more flight parameters of the helicopter, thereby protecting the airframe of the helicopter.

Abstract: An exemplary anti-torque system for a rotorcraft includes a fan located inside of a channel that extends inside of a fuselage from an inlet proximate a forward end of the tail boom to an outlet at an aft end of the tail boom, the outlet is oriented to direct airflow from the channel onto a rudder coupled to a trailing edge of a vertical stabilizer.