An aircraft includes an airframe having at least one wing. A distributed propulsion system is attached to the airframe and includes first and second pluralities of propulsion assemblies. In a vertical takeoff and landing flight mode, each of the propulsion assemblies generates vertical thrust with rotor assemblies of the first plurality of propulsion assemblies rotating in a horizontal plane and rotor assemblies of the second plurality of propulsion assemblies rotating in a parallel horizontal plane. In a forward flight mode, each of the propulsion assemblies generates forward thrust with the rotor assemblies of the first plurality of propulsion assemblies rotating in a vertical plane and the rotor assemblies of the second plurality of propulsion assemblies rotating in a parallel vertical plane. In both the vertical takeoff and landing flight mode and the forward flight mode, a pod assembly coupled to the airframe remains in a generally horizontal attitude.

A reduction gearbox for an aircraft engine, including an input pinion configured to be driven by the aircraft engine, a input gear meshed with the input pinion, a drive gear meshed with the input gear, an output pinion, and an output gear meshed with the output pinion and configured to drive an output shaft of the aircraft engine. The reduction gearbox is selectively configurable between an engaged configuration where the input gear and output pinion are drivingly engaged and a disengaged configuration where the input gear is rotatable independently of the output pinion. The output shaft may drive a propeller and the gearbox may include a propeller brake. A method of driving a generator of a turboprop engine is also discussed.

The aircraft includes a fuselage, a front wing and a rear wing provided to extend laterally from the fuselage for generating lift during cruise, a boom 18 supported by the front wing and the rear wing to be spaced apart from the fuselage, and at least one VTOL rotor that is supported on the boom, and having one or more blades for generating thrust in a vertical direction during take-off and landing, wherein the boom has a shape in a top view in which a barrel forms a curvature in a direction away from the fuselage with respect to a front end and a rear end while extending in a front-back direction, and has a cross section in a front view in which an upper side forms a round curvature, the boom being tapered from an upper side from a lower side, and the lower side is substantially flat.

The aircraft includes a fuselage, a front wing and a rear wing provided to extend laterally from the fuselage for generating lift during cruise, a boom 18 supported by the front wing and the rear wing to be spaced apart from the fuselage, and at least one VTOL rotor that is supported on the boom, and having one or more blades for generating thrust in a vertical direction during take-off and landing, wherein the boom has a shape in a top view in which a barrel forms a curvature in a direction away from the fuselage with respect to a front end and a rear end while extending in a front-back direction, and has a cross section in a front view in which an upper side forms a round curvature, the boom being tapered from an upper side from a lower side, and the lower side is substantially flat.

A rotary wing aircraft that extends along a roll axis between a nose region and an aft region, comprising: at least one first single-blade rotor and at least one second single-blade rotor which are spaced apart from each other along the roll axis; at least one first electric machine and at least one second electric machine which are at least configured to drive in motor mode the at least one first single-blade rotor and the at least one second single-blade rotor for generating lift in hover condition of the rotary wing aircraft; at least one propulsion device that is at least configured to generate forward thrust in forward flight condition of the rotary wing aircraft; and a fixed-wing arrangement that is at least configured to provide lift in the forward flight condition.

A rotary wing aircraft that extends along a roll axis between a nose region and an aft region, comprising: at least one first single-blade rotor and at least one second single-blade rotor which are spaced apart from each other along the roll axis; at least one first electric machine and at least one second electric machine which are at least configured to drive in motor mode the at least one first single-blade rotor and the at least one second single-blade rotor for generating lift in hover condition of the rotary wing aircraft; at least one propulsion device that is at least configured to generate forward thrust in forward flight condition of the rotary wing aircraft; and a fixed-wing arrangement that is at least configured to provide lift in the forward flight condition.

The aircraft motor architecture comprises two reversible electric machines (3, 4), the rotors (10) of which are linked both to the low pressure shaft (1) and to the high pressure shaft (2) by transmissions (11, 12, 13, 14) alternately disengaged depending on the direction of rotation of the rotor (10), the transmissions comprising passive one-way clutches (15, 16, 17, 18), the engagement directions of which are opposed. Independent modes of operation of the machines, as a starter or as an electric generator of each of the shafts, are thus provided.

The aircraft motor architecture comprises two reversible electric machines (3, 4), the rotors (10) of which are linked both to the low pressure shaft (1) and to the high pressure shaft (2) by transmissions (11, 12, 13, 14) alternately disengaged depending on the direction of rotation of the rotor (10), the transmissions comprising passive one-way clutches (15, 16, 17, 18), the engagement directions of which are opposed. Independent modes of operation of the machines, as a starter or as an electric generator of each of the shafts, are thus provided.

A method for calculating torque through a rotor mast of a propulsion system of a tiltrotor aircraft includes receiving the torque being applied through a quill shaft of the rotorcraft. The quill shaft is located between a fixed gearbox and a spindle gearbox, and the spindle gearbox is rotatable about a conversion access. The torque through the rotor mast is determined by using the torque through the quill shaft and the efficiency loss value between the quill shaft and the rotor mast.

A gear system includes a gear assembly having a shaft that is at least partially disposed within a housing of the gear system. A thrust bearing has inner and outer races with the outer race coupled to the housing. A bearing flexure is disposed between the inner race of the thrust bearing and the shaft. The bearing flexure includes a cylindrical cage having at least one shaft journal ring and a plurality of circumferentially distributed axially extending fingers coupled thereto with the shaft journal ring coupled to the shaft. A cylindrical bearing journal has inner and outer surfaces with the outer surface coupled to the inner race of the thrust bearing. Each of a plurality of circumferentially distributed radially extending struts extends between one of the fingers and the inner surface of the cylindrical bearing journal. The bearing flexure has an axial stiffness that is greater than its radial stiffness.