Abstract: A hub assembly for a ducted-rotor aircraft includes a plurality of stator supports, a first integral fitting that attaches to first ends of the stator supports, and a second integral fitting that attaches to second ends of the stator supports. The first fitting includes a plurality of motor attachment portions configured to locate and support a motor of the ducted-rotor aircraft, a plurality of fairing mounts configured to support attachment of an aerodynamic fairing to the hub assembly, and a plurality of stator locators configured to locate respective ones of the plurality of stator supports for attachment to the hub assembly. The first fitting has a body portion with an annular wall that supports the motor attachment portions, the fairing mounts, and the stator locators. The first fitting may be fabricated as a monolith that includes the body portion, motor attachment portions, fairing mounts, and stator locators.

Abstract: A hydraulic actuator has a lower cylinder comprising a lower cylinder extension area and a lower cylinder retraction area, an upper cylinder comprising an upper cylinder extension area and an upper cylinder retraction area, and an actuator shaft. The actuator shaft has a lower cylinder piston disposed in the lower cylinder, an upper cylinder piston disposed in the upper cylinder, a lower shaft connecting the lower cylinder piston to the upper cylinder piston, and an upper shaft extending from the upper cylinder piston and at least partially externally from the upper cylinder. At least one of fluid flow of the lower cylinder matches fluid flow of the upper cylinder and (1) an internal diameter of the lower cylinder is not equal to the an internal diameter of the upper cylinder and (2) a diameter of the lower shaft is not equal to a diameter of the upper shaft.

Abstract: A movable ballast system for an aircraft includes first and second ballast docks secured to the aircraft. The first ballast dock includes a first housing and a first ballast tray secured within the first housing. The first ballast tray includes a plurality of channels. The second ballast dock is positioned aft of a CG of the aircraft and includes a second housing and a second ballast tray secured within the second housing. The second ballast tray includes a plurality of channels. The movable ballast system includes a plurality of movable ballasts, each movable ballast of the plurality of movable ballasts being configured to fit within at least one channel of each of the plurality of channels of the first and second ballast trays.

Abstract: An aggregate-removal method includes placing a metallic article in a tank of fluid, a piece of aggregate being lodged in a feature of the metallic article, and treating the metallic article with sound waves to dislodge the lodged aggregate from the metallic article. An aggregate-identification method includes applying a fluorescent penetrant solution to a metallic article, exposing the metallic article to UV light, and identifying fluorescing aggregate lodged in a feature of the metallic article.

Abstract: An exemplary pitch lock for a tiltrotor aircraft to enable and disable a pitching degree of freedom of a rotor blade assembly includes a first tab coupled to a blade stop assembly, the first tab having a first ramp surface, a second tab coupled to a blade cuff, the second tab having a second ramp surface, a hasp having a central opening to receive the first and the second tab and rollers rotatably coupled to the hasp on opposite sides of the central opening, where the rollers engage the first and second ramp surfaces and retain the first and the second tabs in the central opening.

Abstract: An autonomous cargo delivery aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation. The aircraft includes a fuselage having an aerodynamic shape with a leading edge, a trailing edge and first and second sides. First and second wings are coupled to the fuselage proximate the first and second sides, respectively. A distributed thrust array includes a first pair of propulsion assemblies coupled to the first wing and a second pair of propulsion assemblies coupled to the second wing. A flight control system is operably associated with the distributed thrust array and configured to independently control each of the propulsion assemblies. The first side of the fuselage includes a door configured to provide access to a cargo bay disposed within the fuselage from an exterior of the aircraft with a predetermined clearance relative to the first pair of propulsion assemblies.

Abstract: There is provided a method and a system for finite element (FE) analysis of a composite structure comprising plies arranged according to a stacking sequence and layers of bonding agent. Each layer of bonding agent interconnects two adjacent plies. In-plane properties and out-of-plane properties of the composite structure are received. An FE model of the composite structure is generated by representing the plies by two-dimensional (2D) elements configured to be arranged according to the stacking sequence, representing the layers of bonding agent by three-dimensional (3D) elements, each 3D element configured to interconnect two adjacent 2D elements, and associating the in-plane properties with the 2D elements and the out-of-plane properties with the 3D elements. An FE analysis of the FE model is performed to predict delamination of the composite structure.

Abstract: A rotorcraft having pusher propeller generated power during autorotations. The rotorcraft has an engine powered mode and an autorotation mode. The rotorcraft includes an engine and a drivetrain configured to receive torque and rotational energy from the engine in the engine powered mode. A main rotor system is coupled to the drivetrain and is rotatable to generate lift and forward thrust for the rotorcraft in the engine powered mode. A pusher propeller is coupled to the drivetrain and is rotatable to generate forward thrust for the rotorcraft in the engine powered mode. In the autorotation mode, the pusher propeller is aerodynamically driven responsive to airflow therethrough and the drivetrain is configured to receive torque and rotational energy from the pusher propeller, thereby providing power to the main rotor system.

Abstract: An aircraft includes a wing and a rotor pod mounted to the wing. The rotor pod includes a body having a forward end and an aft end. A propeller is mounted to the body of the rotor pod at the forward end. A control surface is mounted to the body of the rotor pod between the forward and aft ends and extends outwardly from the body. The control surface is displaceable relative to the body between a first control configuration and a second control configuration to control an attitude of the aircraft. The control surface in the first control configuration is closer to the propeller than the control surface in the second control configuration.

Abstract: A method of displacing rotors of an aircraft between a hover mode and an aircraft mode includes rotating a spindle drivingly connected to the rotors about a spindle axis to displace the rotors between the hover and aircraft modes until a component displaceable with the spindle abuts against a downstop of the aircraft and applies a load against the downstop. The method includes passively maintaining the component against the downstop to maintain the load applied against the downstop. An aircraft is also disclosed.

Abstract: A drivetrain for an aircraft includes an engine, a driveshaft receiving rotational energy from the engine and a gearbox including a planetary gear system receiving rotational energy from the driveshaft. The planetary gear system includes a sun gear, planet gears, a ring gear and an integral carrier forming flexured carrier posts. Each flexured carrier post supports a respective one of the planet gears and has a fixed proximal end and a cantilevered distal end. The planetary gear system includes flexured roller races, each having a fixed end and a cantilevered end. The fixed end of each flexured roller race is coupled to the cantilevered distal end of a respective flexured carrier post. The planet gears engage with the flexured roller races to rotate about the flexured carrier posts. The cantilevered ends of the flexured roller races experience cantilevered motion to absorb loads from the planet gears.

Abstract: A tension-torsion strap, for example for a rotor aircraft, including a continuous length of carbon fiber tow arranged in multiple loops to form an elongated member extending between opposing ends and a flexible cover encasing the carbon fiber tow.

Abstract: A tiltrotor assembly has a central hub with a plurality of rotor blades extending therefrom and is configured to rotate about a mast axis to generate lift in a hover position. The central hub is configured to rotate about a tilt axis between the hover position and a forward-flight position such that rotation about the mast axis generates forward thrust. The central hub is surrounded by a segmented duct that includes a thin rotatable inner ring and a wide fixed outer ring. The inner ring is configured to rotate with the central hub about the tilt axis leaving the wide outer ring in a generally horizontal position.

Abstract: An aircraft includes a fuselage, and a wing extending from the fuselage along a spanwise axis. A section of the wing is rotatable about the spanwise axis. A ducted fan is mounted to the section of the wing. The ducted fan has a hub configured to be drivingly engaged by an engine. The hub is rotatable about a fan axis. Blades protrude from the hub between roots mounted to the hub and tips radially spaced from the hub. A duct circumferentially extends about the fan axis and is mounted to the tips of the blades to rotate with the blades about the fan axis. The section of the wing and the ducted fan are rotatable about the spanwise axis between a hover mode in which the fan axis is substantially perpendicular to a ground, and an aircraft mode in which the fan axis is substantially parallel to the ground.

Abstract: An exemplary pitch lock for a tiltrotor aircraft to enable and disable a pitching degree of freedom of a rotor blade assembly includes a first tab coupled to a blade stop assembly, the first tab having a first ramp surface, a second tab coupled to a blade cuff, the second tab having a second ramp surface, a hasp having a central opening to receive the first and the second tab and rollers rotatably coupled to the hasp on opposite sides of the central opening, where the rollers engage the first and second ramp surfaces and retain the first and the second tabs in the central opening.

Abstract: An example of an emergency lubrication system for an aircraft includes a lubricant tank configured to supply a lubricant to a gearbox of the aircraft, a tube coupled between the lubricant tank and the gearbox and comprising a check ball disposed within the tube, a first lubricant line coupled to the tube and a first inlet of the gearbox, and a second lubricant line coupled to the tube and a second inlet of the gearbox.

Abstract: A lubrication system includes a primary lubrication system for a gearbox of the aircraft, the primary lubrication system comprising a first lubricant tank, and an emergency lubrication system for the gearbox. The emergency lubrication system includes a second lubricant tank coupled to a gearbox of an aircraft, a passive thermostat coupled between the second lubricant tank and the gearbox via a lubricant line, a conductor coupled between the passive thermostat and the gearbox and configured to conduct heat from the gearbox to the passive thermostat, and wherein the passive thermostat is configured to open in response to the conductor being exposed to a temperature that exceeds a threshold temperature.

Abstract: A modular tandem tiltrotor aircraft in which the tiltrotor assemblies are operably coupled at the forward and aft ends of the fuselage of the aircraft is disclosed. The modular tandem tiltrotor assemblies are capable of rotating between a vertical lift position and a horizontal flight position. The modular tandem tiltrotor aircraft can be structurally more efficient and lower drag than a conventional tiltrotor, has better control authority and lifting capacity than hybrid-quads and tail-sitters, and has more range than a helicopter or multi-rotor. The modular tandem tiltrotor aircraft can orbit and search over a broad area, or can hover for long periods, depending on the application. Instead of providing a multi-function tandem tiltrotor aircraft that is generally suited for all applications, but not optimized for any, the modular tandem tiltrotor aircraft allows for customized configuration to optimize the aircraft for a particular application.

Abstract: An exemplary length adjustable link includes a tube having an internal bore and internal surface, a first rod end having a first shaft disposed in a first end of the internal bore, a second rod end having a second shaft disposed in a second end of the internal bore, and a member threadably connecting the first rod end to the second rod end.

Abstract: An exemplary spring-loaded link for an aircraft including a spring interposed between a first and a second rod, the spring, when compressed, urging the first rod and the second rod away from each other.