The present disclosure relates to a vertical takeoff and landing (VTOL) aircraft (100) and a propulsion system (600) thereof. The propulsion system (600) comprises a primary rotor (108) configured to couple to an airframe (102) and oriented to generate a vertical thrust relative to the airframe (102), a drivetrain (626) operably coupled to an engine (602) and configured to mechanically drive the primary rotor (108), and a plurality of tiltable secondary rotor assemblies (114) configured to be disposed about the primary rotor (108). The primary rotor (108) comprises a plurality of collective-only variable-pitch blades. Each of the plurality of tiltable secondary rotor assemblies (114) may have a secondary rotor (116) and an electric motor (608) to drive the secondary rotor (116). An electric generator (606) operably coupled to the engine (602) or to the drivetrain (626) may be configured generate electric power for each electric motor (608) of the plurality of tiltable secondary rotor assemblies (114). Each of the plurality of tiltable secondary rotor assemblies (114) is configured to tilt between a vertical configuration (200b) and a horizontal configuration (200a) as a function of a phase of flight of the VTOL aircraft (100).

An un-ducted turbofan engine defining a radial direction and an axial direction that includes a core engine, a fan, a plurality of variable outlet guide vanes, and a pitch change mechanism. Each of the plurality of variable outlet guide vanes are attached in a rotatable manner to the core engine of the un-ducted turbofan engine. The pitch change mechanism is positioned radially between the engine air flowpath and the plurality of variable outlet guide vanes and coupled to at least one variable outlet guide vane of the plurality of variable outlet guide vanes for changing a pitch of the at least one variable outlet guide vane.

A gimbaled rotor assembly for an aircraft. The gimbaled rotor assembly including a static mast; a spherical bearing comprising an inner component and an outer component pivotable relative to each other about a bearing focus, the inner component fixedly coupled to the static mast; a rotor hub rotatably coupled to the outer component, allowing for relative rotation of the rotor hub about a rotor axis and for pivoting together with the outer component about the bearing focus; and a primary hub spring coupling the outer component to the static mast and configured for opposing pivoting of the rotor hub about the bearing focus from a neutral position.

A gimbaled rotor assembly for an aircraft. The gimbaled rotor assembly including a static mast; a spherical bearing comprising an inner component and an outer component pivotable relative to each other about a bearing focus, the inner component fixedly coupled to the static mast; a rotor hub rotatably coupled to the outer component, allowing for relative rotation of the rotor hub about a rotor axis and for pivoting together with the outer component about the bearing focus; and a primary hub spring coupling the outer component to the static mast and configured for opposing pivoting of the rotor hub about the bearing focus from a neutral position.

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.

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.

A turbomachine module with a longitudinal axis comprising an unducted propeller rotated about the longitudinal axis and at least one straightener. The module includes a plurality of unducted variable-pitch stator blades extending along a radial axis, perpendicular to the longitudinal axis, from a fixed casing. The module includes a first stator blade pitch-changing system. The pitch-changing system includes at least one first control that includes a first fixed body connected to the fixed casing and a first body which is axially mobile in relation to the first fixed body and at least one first joining mechanism joining each stator blade to the first mobile body of the first control. The first joining mechanism includes: a joining ring centered on the longitudinal axis, joined to the feet of each stator blade and at least one lever joined, on one hand, to the joining ring and, on the other hand, to the first mobile body of the first control.

A turbomachine module with a longitudinal axis comprising an unducted propeller rotated about the longitudinal axis and at least one straightener. The module includes a plurality of unducted variable-pitch stator blades extending along a radial axis, perpendicular to the longitudinal axis, from a fixed casing. The module includes a first stator blade pitch-changing system. The pitch-changing system includes at least one first control that includes a first fixed body connected to the fixed casing and a first body which is axially mobile in relation to the first fixed body and at least one first joining mechanism joining each stator blade to the first mobile body of the first control. The first joining mechanism includes: a joining ring centered on the longitudinal axis, joined to the feet of each stator blade and at least one lever joined, on one hand, to the joining ring and, on the other hand, to the first mobile body of the first control.

A variable pitch fan assembly includes a plurality of rotating trunnion assemblies, a plurality of counterweight assemblies, a first unison ring gear engaged with the trunnion assemblies, and a second unison ring member that restricts out of synch movement of the counterweights relative to each other.

A variable pitch fan assembly includes a plurality of rotating trunnion assemblies, a plurality of counterweight assemblies, a first unison ring gear engaged with the trunnion assemblies, and a second unison ring member that restricts out of synch movement of the counterweights relative to each other.