A method of increasing a stability speed of a tiltrotor aircraft includes pivoting a rotor assembly having at least three rotor blades from a first position for operating the tiltrotor aircraft in a helicopter mode to a second position for operating the tiltrotor aircraft in an airplane mode, and increasing a stiffness of the rotor assembly when the rotor assembly is in the second position.

An inboard beam includes a body having an upper flange and a lower flange coupled thereto. The upper flange includes a first upper inboard aperture and an upper outboard aperture formed therein. The lower flange includes a first lower inboard aperture and a lower outboard aperture formed therein. An upper beam fitting is coupled to the upper flange and lower beam fitting is coupled to the lower flange. The upper beam fitting includes a first upper inboard post. The upper beam fitting includes an upper outboard post extending parallel to the inboard post. The lower beam fitting includes a first lower inboard post. The lower beam fitting includes a lower outboard post extending parallel to the lower inboard post.

An inboard beam includes a body having an upper flange and a lower flange coupled thereto. The upper flange includes a first upper inboard aperture and an upper outboard aperture formed therein. The lower flange includes a first lower inboard aperture and a lower outboard aperture formed therein. An upper beam fitting is coupled to the upper flange and lower beam fitting is coupled to the lower flange. The upper beam fitting includes a first upper inboard post. The upper beam fitting includes an upper outboard post extending parallel to the inboard post. The lower beam fitting includes a first lower inboard post. The lower beam fitting includes a lower outboard post extending parallel to the lower inboard post.

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.

A turbomachine module includes a rotor supporting variable pitch blades, and an inner annular shaft, a blade pitch control device, a device for feathering at least one blade comprising at least one gas generator placed between a body and a movable member. The control device and the feathering device are situated radially between the shaft and the blades, the movable member is coupled with the at least one blade and capable, under the action of the gas generated and/or released by the generator, of being moved into a reference position wherein it entails a feathered position to the at least one blade.

This invention employs a generic axial modulating mechanism to manipulate the pitch of the blades of a fan or propeller; conceptually, this is a threaded bolt and nut where the threaded bolt would be analogous to a rotating shaft, with an acme thread (i.e. the rotor thread) on its exterior, and the nut would be analogous to the axial modulator of this teaching. The nut, or axial modulator, is further spun above and beyond the rotation in the rotating bolt or rotating shaft. The axial motion of the axial modulator is then deployed to do useful work i.e. manipulate the pitch of the blades of a fan or propeller. This invention is a continuation in part of a previous variant disclosed where the means of modulating the axial modulator was magnetic. The variation introduced in this teaching instead achieves the modulation using a gear-driven arrangement.

This invention employs a generic axial modulating mechanism to manipulate the pitch of the blades of a fan or propeller; conceptually, this is a threaded bolt and nut where the threaded bolt would be analogous to a rotating shaft, with an acme thread (i.e. the rotor thread) on its exterior, and the nut would be analogous to the axial modulator of this teaching. The nut, or axial modulator, is further spun above and beyond the rotation in the rotating bolt or rotating shaft. The axial motion of the axial modulator is then deployed to do useful work i.e. manipulate the pitch of the blades of a fan or propeller. This invention is a continuation in part of a previous variant disclosed where the means of modulating the axial modulator was magnetic. The variation introduced in this teaching instead achieves the modulation using a gear-driven arrangement.

An exemplary spring-loaded link for an aircraft including a spring interposed between a first and a second rod, the spring, when compressed, urging the first rod and the second rod away from each other.

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).