Abstract: A tiltrotor aircraft has a vertical takeoff and landing flight mode and a forward flight mode. The aircraft includes an airframe having at least one wing. First and second oppositely disposed booms extend longitudinally from the at least one wing. Forward rotors are coupled to the forward ends of the booms and aft rotors are coupled to the aft ends of the booms. The forward rotors are reversibly tiltable between a vertical lift orientation, wherein the forward rotors are above the booms, and a forward thrust orientation, wherein the forward rotors are forward of the booms. The aft rotors are reversibly tiltable between a vertical lift orientation, wherein the aft rotors are below the booms, and a forward thrust orientation, wherein the aft rotors are aft of the booms.

Abstract: A battery cell assembly, including a cell having a first electrode and a second electrode rolled together to form a cylindrical shape; a first end cap disposed on a first end of the cell and contacting the first electrode; a second end cap disposed on a second end of the cell and contacting the second electrode; and a jacket configured to couple the first end cap and the second end cap to the cell, the jacket made from a non-conductive material.

Abstract: Embodiments are directed to systems and methods for utilizing a two-degree-of-freedom model-following control law within an architecture of nested loop functions. This allows for the separation of command and feedback path requirements and enables the restrictions of the inner loops to be applied to the outer loop feedbacks. This method of restriction allows a better allocation of coordinated authority between the loops.

Abstract: A fitting for securing a rotor blade in pivotable engagement with a yoke that is coupled to a mast of an aircraft for rotation therewith about a mast axis has a body that extends from an inboard end to an outboard end. The body of the fitting has an opening that extends into the body from the outboard end and that is adapted to receive a root end of the blade. The body further has a first bearing race that is defined along an outer surface of the body and is located between the inboard and outboard ends. The body further has an array of apertures that is located between the inboard end and the first bearing race, each aperture adapted to receive a respective fastener for retaining the blade within the opening.

Abstract: In some examples, an aircraft gearbox comprises a plurality of gears and a hybrid lubrication system to lubricate the plurality of gears. The plurality of gears comprises a first gear and a second gear. The plurality of gears operable to rotate based on torque received from a driveshaft. The hybrid lubrication system comprises a pressurized lubrication system and a non-pressurized lubrication system. The pressurized lubrication system comprises a nozzle to spray a lubricant onto the first gear. The non-pressurized lubrication system comprises a reservoir to catch a portion of the lubricant from the pressurized lubrication system. The second gear is operable to disperse the lubricant across others of the plurality of gears based on the second gear rotating through the portion of the lubricant.

Abstract: A battery cell assembly, including a rolled cell formed from a first electrode and a second electrode rolled together about a longitudinal axis. The rolled cell includes a primary section in which the first electrode and the second electrode overlap in a radial direction from the longitudinal axis, and a first extension end extending from a first longitudinal end of the primary section and formed from a first edge section of the first electrode. The first edge section includes a first folded portion folded to contact an adjacent portion of the first edge section. The battery cell assembly further includes a first end cap coupled to the rolled cell and contacting the first folded portion.

Abstract: Disclosed are systems and methods for testing aircraft engine that are not currently associated with a functional aircraft or systems. For testing, systems on the engine being tested are connected with the reciprocating systems (e.g., engine electronic controls, main and motive fuel) on a fully functional aircraft using conduits that have been extended to lengths enabling the connection.

Abstract: An example of an aerial vehicle includes a rudder removably connected to the aerial vehicle by a twist lock mechanism. The twist lock mechanism is biased in a locked position by an elastic member.

Abstract: An autopilot recoupling system for a rotorcraft having an automatic flight control system with multiple layers of flight augmentation. The autopilot recoupling system includes an autopilot recoupling input operable to generate an autopilot recoupling signal. An autopilot recoupling signal processor is communicably coupled to the autopilot recoupling input. The autopilot recoupling signal processor is configured to receive the autopilot recoupling signal from the autopilot recoupling input and responsive thereto, determine a state of the automatic flight control system, activate a trim systems layer of the automatic flight control system if the trim systems layer is not active, engage an attitude retention systems layer of the automatic flight control system if the attitude retention systems layer is disengage and recouple an autopilot systems layer of the automatic flight control system.

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: 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: In an embodiment, a ducted fan assembly includes a housing that further includes a rotor. The ducted fan assembly also includes a rim that extends around at least a portion of a perimeter of the ducted fan assembly, where the rim defines an opening surrounding at least a portion of the housing. The ducted fan assembly also includes a skin that is attached to the rim and extends around the at least a portion of a perimeter of the ducted fan assembly to form a leading edge of the ducted fan assembly. The ducted fan assembly also includes a blade positioned on the rim underneath the skin.

Abstract: A tip gap monitoring system for a ducted aircraft having a proprotor system including a duct and a plurality of proprotor blades includes sensors coupled to the proprotor system. The sensors are configured to detect one or more parameters of the proprotor system to form a plurality of sensor measurements. The tip gap monitoring system also includes a flight control computer in data communication with the sensors. The flight control computer includes a tip gap measurement module configured to determine a tip gap distance between the duct and the proprotor blades based on the sensor measurements.

Abstract: An aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation. The aircraft has an airframe including first and second wings with a fuselage extending therebetween. A propulsion assembly is coupled to the fuselage and includes a counter-rotating coaxial rotor system that is tiltable relative to the fuselage to generate a thrust vector. A flight control system is configured to direct the thrust vector. In the VTOL orientation, the first wing is forward of the fuselage, the second wing is aft of the fuselage and the coaxial rotor system is configured to provide thrust in line with a yaw axis of the aircraft. In the biplane orientation, the first wing is below the fuselage, the second wing is above the fuselage and the coaxial rotor system is configured to provide thrust in line with a roll axis of the aircraft.

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: A propulsion assembly for an aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a biplane orientation. The propulsion assembly includes a housing coupled to the fuselage of the aircraft. A coaxial rotor system includes a first rotor assembly and a second rotor assembly that are rotatable about a common axis of rotation. The first rotor assembly counter-rotates relative to the second rotor assembly. A motor assembly is operably associated with the coaxial rotor system. The motor assembly provides torque and rotational energy to the first rotor assembly and the second rotor assembly. A gimbal assembly couples the coaxial rotor system to the housing such that the coaxial rotor system is tiltable relative to the fuselage to generate a thrust vector.

Abstract: An aircraft includes an airframe with first and second wings having a fuselage extending therebetween. A propulsion assembly is coupled to the fuselage and includes a counter-rotating coaxial rotor system that is tiltable relative to the fuselage to generate a thrust vector. Tail assemblies are coupled to wingtips of the first and second wings each having an elevon that collectively form a distributed array of elevons. A flight control system is configured to direct the thrust vector of the coaxial rotor system and to control movements of the elevons such that the elevons collectively provide pitch authority and differentially provide roll authority for the aircraft in the biplane orientation. In addition, when the flight control system detects an elevon fault, the flight control system is configured to perform corrective action responsive thereto at a distributed elevon level or at a coordinated distributed elevon and propulsion assembly level.

Abstract: A duct for a ducted-rotor aircraft includes a hub, a duct ring, and a plurality of stators that extend outward from the hub. The duct ring defines a trailing edge. The duct includes one or more fittings, such as a system of fittings. Each fitting has a body that defines a first attachment interface that is configured to couple to structure of the duct ring and a second attachment interface that is configured to couple to one of the plurality of stators. The first and second attachment interfaces are spaced from each other such that when the fittings are coupled to the duct ring and the plurality of stators, all or substantially all of each of the plurality of stators are located aft of the trailing edge of the duct ring.

Abstract: A power management system for a multi engine rotorcraft having a main rotor system with a main rotor speed. The power management system includes a first engine that provides a first power input to the main rotor system. A second engine selectively provides a second power input to the main rotor system. The second engine has at least a zero power input state and a positive power input state. A power anticipation system is configured to provide the first engine with a power adjustment signal in anticipation of a power input state change of the second engine during flight. The power adjustment signal causes the first engine to adjust the first power input to maintain the main rotor speed within a predetermined rotor speed threshold range during the power input state change of the second engine.

Abstract: Various implementations described herein are directed to an emergency lubrication system for a tiltrotor aircraft. The emergency lubrication system includes a pressurized material chamber, a lubrication chamber, a first valve between the pressurized material chamber and the lubrication chamber, a gearbox, and a second valve between the lubrication chamber and the gearbox. The first valve is configured to operate in a first mode when the emergency lubrication system is in a first configuration and a second mode when the emergency lubrication system is in a second configuration.