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 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: 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 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: 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: 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: 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: The present invention includes a rotor-blade span-balancing system, including a span-balance pocket in a surface of a rotor blade; a cover operably configured to cover the span-balance pocket, wherein the cover is operably configured to be substantially flush with the surface of the rotor blade surface when covering the span-balance pocket, and wherein the cover includes a cover boss for reacting centrifugal force of the cover into the rotor blade; and one or more span-balance weights attached to the cover to span-balance the rotor blade.

Abstract: An exemplary blade lock for a tiltrotor aircraft to enable and disable a folding degree of freedom and a pitching degree of freedom of a rotor blade assembly includes a link pivotally connected to a lever and a bellcrank, where the link is in a center position when the lever is in a locked position disabling the folding degree of freedom and the lever is secured in the locked position when the link is positioned in an over-center position.

Abstract: A drivetrain for an aircraft includes an engine, a driveshaft to receive rotational energy from the engine and a gearbox including a multistage planetary gear system to receive rotational energy from the driveshaft. The multistage planetary gear system includes an integral multistage ring gear system having flanged and cantilevered ends. The integral multistage ring gear system forms a first stage ring gear at the cantilevered end and a second stage ring gear interposed between the flanged end and the first stage ring gear. The multistage planetary gear system includes a first stage sun gear, first stage planet gears and a first stage carrier. The first stage planet gears mate with the first stage ring gear. The multistage planetary gear system includes a second stage sun gear, second stage planet gears and a second stage carrier. The second stage planet gears mate with the second stage ring gear.

Abstract: A rotorcraft has a horizontal stabilizer movable about an axis of rotation and a horizontal stabilizer control system configured to control the horizontal stabilizer to at least one of move the rotorcraft into a minimum drag position, maintain the aircraft in a minimum drag position, efficiently achieve a maneuver, enter efficient autorotation, and maintain efficient autorotation.

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.

Abstract: Embodiments are directed to an aircraft fuselage comprises two keel beams and two roof beams. Each keel beam is formed as a single component having no joints. Each keel beam comprises a first portion that is configured to define a floor of an aircraft and a second portion that is configured to define a tail section of an aircraft. The second portion is positioned at an angle relative to the first portion. Each roof beam is coupled to the second portion of a corresponding keel beam at a point remote from the first portion. Each roof beam and a corresponding keel beam are positioned along a single butt line relative to an aircraft fuselage centerline. Frame members are coupled to both keel beams and both roof beams.

Abstract: An exemplary proprotor blade assembly includes a structural skin extending spanwise from a root to a tip and along a chord from leading edge to a trailing edge and a structural core positioned inside of the structural skin, the structural skin comprising hex-shaped structures oriented normal to the structural skin.

Abstract: An annular spar for a ducted-rotor of an aircraft may be fabricated from composite material, such as carbon-fiber-reinforced plastic (CFRP). The spar may include an annular plate, a first circumferential flange that extends from an outer edge of the plate, and a second circumferential flange that extends from an inner edge of the plate. The first and second circumferential flanges may taper inwardly toward a center axis of the spar. The spar may be constructed of a plurality of layers of CFRP. One or more of the layers may be fabricated from a single ply of CFRP, and one or more other layers may be fabricated from a plurality of plies of CFRP. The spar may exhibit a coefficient of thermal expansion (CTE) that allows an associated tip gap to remain essentially constant throughout a range of operating temperatures.

Abstract: A device to verify main rotor swashplate positioning includes an inner surface of a first section and a gradient surface of a second section. The gradient surface of the second section may have a plurality of graduation indications. In one implementation, the inner surface of the first section at least partially defines a travel arc that is parallel to and concentric with the inner surface. In such an implementation, the device may be configured to move along the travel arc as it rotates about a collective sleeve to contact a swashplate lug.

Abstract: A strut assembly for a vibration isolation device is disclosed, comprising a piston spindle; a first elastomeric member and a second elastomeric member bonded to the piston spindle and in contact with an upper housing and a lower housing, respectively; a first strut support and a second strut support attached to or integral with the upper housing and the lower housing, respectively; a first strut spindle and the second strut support configured to be placed in the first strut support and the second strut support, respectively; and one or more removable struts configured to be engaged to the first strut spindle and to the second strut spindle, wherein at least one of the first or second strut spindles is removable such that the one or more struts can be replaced without breaking a bonding of the first elastomeric member, the second elastomeric member, or both.

Abstract: An exemplary clamp system for securing a proprotor blade in a stowed position includes a clamp having a pair of opposing pads operable between an open position to receive a portion of a proprotor blade between the pair of opposing pads and a closed position to grip the portion of the proprotor blade with the pair of opposing pads and a rotary actuator in connection with the clamp to operate the clamp between the open and the closed position.

Abstract: Embodiments are directed to a rotor mast for an aircraft comprising a shaft portion, a carrier portion having a plate and a web, and frame segments that separate the web from the plate at a fixed distance. The shaft portion, the plate, the web, and the frame segments are as single component. A plurality of first holes are formed in the plate, and a plurality of second holes are formed in the web. Pairs of the first and second holes are aligned. Posts are mounted between each pair of first and second holes. Pinion gears are mounted on the posts. Roller bearings are mounted between the posts and pinion gears. An open region of the web is configured to allow a sun gear to mesh with the pinion gears.

Abstract: A landing gear assembly for an aircraft includes a landing member and an actuation mechanism coupled to the landing member. The actuation mechanism is configured to selectively actuate the landing member into a first landing position and a second landing position. The landing member is configured to support the aircraft in either the first landing position or the second landing position.