An electric propulsion system for a vertical take-off and landing (VTOL) aircraft, the electric propulsion system including an electrical motor having a stator and a rotor. The electric propulsion system may include a main shaft possessing at least one shoulder on an outer surface of the main shaft. The electric propulsion system may include a gearbox assembly comprising a sun gear that is concentrically aligned with the main shaft at least one planetary gear that interfaces with the sun gear. The electric propulsion system may include a planetary carrier, wherein a center of the planetary carrier is concentrically aligned with the main shaft. The electric propulsion system may include a propeller flange assembly that travels through the rotor, and an axial buttress positioned in the at least one shoulder located on the main shaft.

A method of assembling an aircraft gearbox. The method includes mounting an outer race and a plurality of rollers of a roller bearing in an opening of a gearbox housing, mating a cylindrical guide sleeve having a lead-in chamfer with a gear assembly having a gear and a cylindrical shaft such that a trailing shoulder of the guide sleeve is positioned proximate a leading shoulder of the shaft, the shaft including an inner race of the roller bearing, axially passing the lead-in chamfer of the guide sleeve through the plurality of rollers, radially outwardly urging the rollers toward the outer race with the guide sleeve, axially passing the leading shoulder of the shaft through the plurality of rollers, positioning the inner race relative to the plurality of rollers to form the roller bearing and removing the guide sleeve from the gear assembly.

A method of assembling an aircraft gearbox. The method includes mounting an outer race and a plurality of rollers of a roller bearing in an opening of a gearbox housing, mating a cylindrical guide sleeve having a lead-in chamfer with a gear assembly having a gear and a cylindrical shaft such that a trailing shoulder of the guide sleeve is positioned proximate a leading shoulder of the shaft, the shaft including an inner race of the roller bearing, axially passing the lead-in chamfer of the guide sleeve through the plurality of rollers, radially outwardly urging the rollers toward the outer race with the guide sleeve, axially passing the leading shoulder of the shaft through the plurality of rollers, positioning the inner race relative to the plurality of rollers to form the roller bearing and removing the guide sleeve from the gear assembly.

Disclosed is an aircraft accessory drive system comprising: a drive shaft configured to provide a drive input; a critical accessory directly coupled to the drive shaft so as to be directly driven by the drive shaft; a parasitic drive system configured to transmit drive input from the drive shaft to one or more less critical accessories, wherein the parasitic drive system comprises a torque limiter configured to decouple the parasitic drive system from the drive shaft and the critical accessory in response to a jam affecting the parasitic drive system or one or more of the less critical accessories. Also disclosed are a gas turbine engine comprising an aircraft accessory drive system, and an aircraft comprising an aircraft accessory drive system.

An assembly is provided for an aircraft propulsion system. This assembly includes a sun gear, a ring gear, a plurality of intermediate gears, a carrier, a first brake and a second brake. The sun gear is rotatable about a centerline axis. The ring gear circumscribes the sun gear and is rotatable about the centerline axis. The intermediate gears are arranged circumferentially about the centerline axis. Each of the intermediate gears is meshed between the sun gear and the ring gear. The carrier is rotatable about the centerline axis. Each of the intermediate gears is rotatably mounted to the carrier. The first brake is configured to slow and/or stop rotation of the ring gear about the centerline axis. The second brake is configured to slow and/or stop rotation of the carrier about the centerline axis.

An assembly is provided for an aircraft propulsion system. This assembly includes a sun gear, a ring gear, a plurality of intermediate gears, a carrier, a first brake and a second brake. The sun gear is rotatable about a centerline axis. The ring gear circumscribes the sun gear and is rotatable about the centerline axis. The intermediate gears are arranged circumferentially about the centerline axis. Each of the intermediate gears is meshed between the sun gear and the ring gear. The carrier is rotatable about the centerline axis. Each of the intermediate gears is rotatably mounted to the carrier. The first brake is configured to slow and/or stop rotation of the ring gear about the centerline axis. The second brake is configured to slow and/or stop rotation of the carrier about the centerline axis.

An aircraft includes a fuselage, a wing structure and a tail assembly, and also at least one propeller having the general shape of a ring. The propeller includes a rotor formed by an annular element having blades projecting outwardly therefrom, and a likewise annular base coaxial to the annular element and on which the annular element can turn under the action of a driver. The base is coaxial to the fuselage and integrated into the shell constituting the fuselage. The blades of the rotor are arranged outside the shell.

Commands, including a first and second command associated with a first and second rotor module, are determined based at least in part on a set of desired forces or moments and a plurality of health metrics, including by determining a plurality of differences between the plurality of health metrics and a threshold and assigning a lower thrust value to the first command based at least in part on the first difference and a higher thrust value to the second command based at least in part on the second difference, where the first difference indicates a higher degree of wear on the first rotor module than the second difference indicates for the second rotor module. The commands are sent to the rotor modules and after the commands are performed, updated health metrics are determined.

To provide an unmanned aerial vehicle that eliminates or minimizes the laboriousness involved in optimal pitch adjustment of propellers while eliminating or minimizing complexity and instability in airframe structure and/or flight programs. This object is solved by an unmanned aerial vehicle that is provided with a plurality of rotors and that includes: a center frame that is a central portion of an airframe of the unmanned aerial vehicle; and a plurality of arms extending radially from the center frame in plan view. A plurality of motors that are driving sources of the respective rotors are provided in the center frame. The plurality of rotors are supported by the respective arms. Each arm of the arms has a hollow cylindrical structure. A motive power transmission member configured to transmit a driving force of each motor of the motors to the each rotor is provided in the each arm.

A tiltrotor aircraft is designed to accommodate rotors of different diameters, as well as corresponding wings and fuselages with different span and length, while maintaining very high parts commonality, especially with respect to drive train and power source. This enables design and operation of a fleet of such aircraft with significantly different rotor diameters, which are nevertheless optimized for different missions. In preferred embodiments the rotors are configured to have high stiffness and low weight to reduce aero-structural dynamic issues across the fleet. Also in preferred embodiments drive systems are designed for a full range of speed, torque, and power associated with all intended rotors. Turboshaft engine speeds are restricted to a narrow RPM range, so that a single gearset can be replaced to achieve the desired rotor RPM. Also in preferred embodiments, aircraft in a fleet can differ in folded length, empty weight, payload length by up 50%.