Abstract: A spinner is described that can provide aerodynamic advantages for vertical takeoff and landing (VTOL) aircraft. The spinner can be shaped with multiple faces divided by chines. The chines can run down the edge of the spinner to fairings that can cover rotor blades and/or couplings between rotor blades and the rotor hubs of the aircraft. During forward flight the rotor blades can be folded down into recesses on the spinner. The spinner and fairings can provide aerodynamic advantages in addition to protection for sensitive components within the rotor and blades apparatus. This improves efficiency and allows the aircraft to fly faster.

Abstract: A rotor system includes a rotor duct; at least one rotor blade that includes an outboard end; a tip extension mechanism affixed at the outboard end of the at least one rotor blade, the tip extension mechanism including at least one shim, the at least one rotor blade with the tip extension mechanism affixed thereto including an extended rotor blade; and a blade tip affixed to an outboard end of the extended rotor blade, wherein the blade tip is affixed to the extended rotor blade via at least one removable fastener.

Abstract: A rotor system for a rotorcraft includes a rotor hub having a plurality of blade grips coupled thereto. Each blade grip has a rotor blade coupled thereto. A fairing is disposed at least partially around the rotor hub. Each of a plurality of lead-lag dampers is coupled to at least a respective one of the blade grips. Each lead-lag damper has a damper heat exchanger and a fluid pump operably associated therewith. A fairing heat exchanger is in fluid communication with the damper heat exchangers and the fluid pumps. Each lead-lag damper is configured to drive the respective fluid pump responsive to damping operations to pump a cooling fluid from the respective damper heat exchanger to the fairing heat exchanger.

Abstract: One embodiment is an electric drive system including a plurality of redundant motors, wherein power generated by the plurality of motors is used to drive a rotor system comprising a rotor shaft having a plurality of rotor blades connected thereto via a swashplate; a gear box associated with the plurality of redundant motors; a cyclic actuation system for controlling an individual pitch of the rotor blades connected to the swashplate; and at least one structural element for retaining the redundant motors, the gear box, and the cyclic actuation system together as a single integrated unit.

Abstract: A method of offset load testing a tubular composite specimen with two pairs of aligned holes and having at least one defect, the method comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; securing the pair of arms using a fastener assembly in each of the two pairs of aligned holes; and moving the mobile arm to impart an offset load force to the tubular specimen. One aspect includes a method of offset load testing comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; providing a tubular composite specimen with a top portion and a bottom portion; securing the pair of arms to the top and bottom portions of the tubular composite specimen; and moving the mobile arm to impart an offset load force to the tubular composite specimen.

Abstract: A propped cantilever carrier is described that can be used in planetary gear systems. The carrier can comprise cantilevered arms extending outward from a central hub. At the end of each cantilever a post can extend downward that is configured to receive bearings and gears. A plate can comprise a hole for each post in the carrier. When the plate is coupled to the carrier it can hold the bearings and gears in place and provide added strength to the carrier. The strength benefits are large compared to the light weight of the carrier (with plate) apparatus.

Abstract: Embodiments are directed to systems and methods for two or more cured composite assemblies that are bonded together to form a tubular composite structure, wherein each of the cured composite assemblies do not have a tubular shape. The tubular composite structure may form a spar for an aerodynamic component, for example. The two or more cured composite assemblies may comprise carbon or fiberglass composite materials or a combination of materials. Each of the cured composite assemblies may further comprise axial edges that are configured to be bonded to another of the cured composite assemblies, wherein the axial edges have a sloped shape. An adhesive agent may be applied on the axial edges for bonding two cured composite assemblies. Alternatively, or additionally, one or more fasteners may be used to attach the axial edges of at least two cured composite assemblies.

Abstract: In an embodiment, a method includes acquiring a current condition indicator of a condition indicator set associated with an operating condition of a machine, the condition indicator set indicating sensor readings associated with an operating element of the machine under the operating condition. The method also includes determining, by a data server, a relative trend significance over a trend window of the condition indicator set based, at least in part, on an evaluation of the trend window in relation to a historical window of the condition indicator set. The method also includes determining, by the data server, whether trend criteria associated with the operating element is satisfied, where the trend criteria may include criteria related to the relative trend significance. The method also includes executing, by the data server, an alerting process in response to the determining that the trend criteria is satisfied.

Abstract: A duct for a ducted-rotor aircraft may include an internal structure and an aerodynamic exterior skin that is adhesively bonded to the internal structure. The skin may include a leading-edge portion disposed at an inlet of the duct and an inner portion disposed along an interior of the duct. The inner portion of the skin may be bonded to the internal structure with a first bondline of adhesive and the leading-edge portion of the skin may be bonded to the inner portion of the skin with a second bondline of adhesive. One or both of the first and second bondlines of adhesive may be of non-uniform thickness to take up tolerance stackups between the inner portion of the skin, the leading-edge portion of the skin, and the internal structure.

Abstract: A sensor for monitoring rotors includes a rotating shaft coupled to a set of rotor blades and a non-rotating tube at least partially disposed within the rotating shaft and coupled to the rotating shaft. The non-rotating tube includes a first end and a second end, a sensor mount disposed within the non-rotating tube proximate to the second end of the non-rotating tube. One or more sensors are attached to the sensor mount.

Abstract: In accordance with an embodiment, a method of operating an aircraft includes operating the aircraft in a first mode including determining an attitude based on a pilot stick signal, where a translational speed or an attitude of the aircraft is proportional to an amplitude of the pilot stick signal in the first mode; transitioning from the first mode to a second mode when a velocity of the aircraft exceeds a first velocity threshold; and operating the aircraft in the second mode where the output of the rate controller is proportional to the amplitude of the pilot stick signal.

Abstract: A charge control system includes a lithium battery configured to provide lithium battery power to a set of electrical loads, a user signaling device, and control circuitry coupled with the lithium battery and the user signaling device. The control circuitry is operative to: (A) detect availability of charge from an external charger, (B) in response to detection of the availability of charge from the external charger and prior to controlling the external charger to adjust the amount of charge stored by the lithium battery, perform a set of pre-charging assessment operations, and (C) based on the set of pre-charging assessment operations, provide a user notification via the user signaling device, the user notification indicating whether the lithium battery is properly setup for charge adjustment. When the user signaling device generates the user notification, the user is informed that the utility vehicle is properly connected to the external charger.

Abstract: A technique for operating an aerial vehicle involves enabling a vertical takeoff and landing (VTOL) propeller of the aerial vehicle to rotate freely. The VTOL propeller is coupled with a VTOL motor (e.g., a 3-phase brushless DC motor). The technique further involves detecting when the VTOL propeller rotates to a predefined position relative to a direction of flight for the aerial vehicle (e.g., when blades of the VTOL propeller extend along an axis that is parallel to the direction of flight). The technique further involves, in response to detecting that the VTOL propeller has rotated to the predefined position, providing a load from the VTOL motor that inhibits further rotation of the VTOL propeller. Accordingly, while the aerial vehicle is in fixed wing horizontal flight, the controller is able to align the VTOL propeller in the direction of horizontal flight to minimize drag from the VTOL propeller.

Abstract: A technique for generating analog waveforms includes combining a desired, in-band signal with a randomizing, out-of-band signal at an input of a DAC, operating the DAC to generate DAC output based on a combination of the desired signal and the randomizing signal, and filtering the DAC output to pass the desired signal while removing the randomizing signal.

Abstract: A composite yoke includes a plurality of packs of unidirectional plies and at least one pack of chopped fibers disposed between two adjacent packs of unidirectional plies. A method of manufacturing a composite yoke includes arranging a plurality of plies of unidirectional fibers to form a first pack of unidirectional plies, arranging a layer of chopped fibers on the first pack of unidirectional plies, arranging a plurality of plies of unidirectional fibers on to form a second pack of unidirectional plies on the layer of chopped fibers, curing the composite yoke to form a cured composite yoke, and cutting excess material from the first pack of unidirectional plies, the layer of chopped fibers, and the second pack of unidirectional plies to form a plurality of arms.

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: A method of simulating an aircraft one-engine inoperative (“OEI”) event includes operating a supplemental power unit (“SPU”) at a first SPU power level less than an SPU contingency power rating, operating a primary engine at a first primary-engine power level, reducing the primary-engine power level to less than the first primary-engine power level, and maintaining a sum of the primary-engine power level and the SPU power level at a power level substantially equal to the SPU contingency power rating.

Abstract: One embodiment is an electric drive system for an aircraft including a motor, a gear box associated with the motor, and a cooling fan for drawing air into the unit across an electronic component to cool the electronic component and for expelling air into an oil cooler for cooling oil contained therein. The electric drive system further includes an oil distribution system for distributing oil cooled by the oil cooler to at least one motor and at least one gearbox, the distributed oil being used to cool the motor and the gearbox, a reservoir for collecting the distributed oil after it has been used to cool the motor and the gearbox, and at least one structural element for retaining the motor, gearbox, the cooling fan, the oil distribution system, and the reservoir together as a unit.

Abstract: A system and method for protecting a rotorcraft from entering a vortex ring state, the method including monitoring a vertical speed of a rotorcraft, comparing the vertical speed to a vertical speed safety threshold, and performing vortex ring state (VRS) avoidance in response to the vertical speed exceeding the vertical speed safety threshold. The performing the VRS avoidance includes determining a power margin available from one or more engines of the rotorcraft, limiting the vertical speed of the rotorcraft in response to the power margin exceeding a threshold, and increasing a forward airspeed of the rotorcraft in response to the power margin not exceeding the threshold.

Abstract: A ducted propulsion assembly for an aircraft includes a duct and a plurality of stators. The distal ends of the stators are coupled to the duct. The ducted propulsion assembly includes a line replaceable centerbody assembly isostatically coupled to the proximal ends of the stators. The line replaceable centerbody assembly includes one or more electric motors driving an output driveshaft. The ducted propulsion assembly also includes a proprotor assembly interchangeably coupled to and rotatable with the output driveshaft of the line replaceable centerbody assembly. The proprotor assembly is rotatable in a rotational plane to generate thrust.