A proprotor system for tiltrotor aircraft having a helicopter mode and an airplane mode. The proprotor system includes a hub and a plurality of proprotor blades coupled to the hub such that each proprotor blade is operable to independently flap relative to the hub and independently change pitch. In the airplane mode, the proprotor blades have a first in-plane frequency greater than 2.0/rev.

A proprotor system for tiltrotor aircraft having a helicopter mode and an airplane mode. The proprotor system includes a hub and a plurality of proprotor blades coupled to the hub such that each proprotor blade is operable to independently flap relative to the hub and independently change pitch. In the airplane mode, the proprotor blades have a first in-plane frequency greater than 2.0/rev.

A method of selectively preventing flapping of a rotor hub includes providing a flapping lock proximate to a rotor hub and shaft assembly and moving the flapping lock from an unlocked position to a locked position, the flapping lock operable in the locked position to prevent at least some flapping movement of the rotor hub relative to the shaft, the flapping lock operable in the unlocked position to allow the at least some flapping movement of the rotor hub relative to the shaft.

A method of selectively preventing flapping of a rotor hub includes providing a flapping lock proximate to a rotor hub and shaft assembly and moving the flapping lock from an unlocked position to a locked position, the flapping lock operable in the locked position to prevent at least some flapping movement of the rotor hub relative to the shaft, the flapping lock operable in the unlocked position to allow the at least some flapping movement of the rotor hub relative to the shaft.

A multi-rotor unmanned aerial vehicle (UAV) comprises: a fuselage; a plurality of rotor mechanisms disposed on the fuselage, each rotor mechanism including a rotor; and a plurality of connection mechanisms disposed on the fuselage. The plurality of connection mechanisms have a one-to-one correspondence with the plurality of rotor mechanisms, each connection mechanism corresponding to one of the plurality of rotor mechanisms. Each rotor mechanism is movably connected to the fuselage through the corresponding connection mechanism; and the plurality of rotor mechanisms are configured to be rotated with respect to the corresponding connection mechanisms to cause the plurality of rotor mechanisms to overlap with each other and form a rotor mechanism assembly.

A multi-rotor unmanned aerial vehicle (UAV) comprises: a fuselage; a plurality of rotor mechanisms disposed on the fuselage, each rotor mechanism including a rotor; and a plurality of connection mechanisms disposed on the fuselage. The plurality of connection mechanisms have a one-to-one correspondence with the plurality of rotor mechanisms, each connection mechanism corresponding to one of the plurality of rotor mechanisms. Each rotor mechanism is movably connected to the fuselage through the corresponding connection mechanism; and the plurality of rotor mechanisms are configured to be rotated with respect to the corresponding connection mechanisms to cause the plurality of rotor mechanisms to overlap with each other and form a rotor mechanism assembly.

During a vertical landing state, it is decided whether to switch from the vertical landing state to a self adjusting state. The VTOL vehicle includes the flight controller, the rotor, and a fuselage where the rotor is coupled to the fuselage via a vertical connector. If it is so decided, there is a switch from the vertical landing state to the self adjusting state. During the self adjusting state, a control signal for a rotor is generated where the control signal causes: (1) the rotor to rotate during the self adjusting state and (2) the VTOL vehicle to remain in a fixed position during the self adjusting state, in response to the control signal, and independent of docking infrastructure. During a rotors off state, a rotor off control signal is generated for the rotor that causes the rotor to turn off.

A gimbal joint may employ a plurality of wear sleeves, each disposed between a pin or pin receptive bore of a first structure and a corresponding bore or pin of a second structure and between another pin or bore of the second structure and a corresponding bore or pin of a third structure. Each of these structures may be adapted to rotate in a single plane, with one structure adapted to also tilt about a first axis, and one other structure adapted to tilt about a second axis. Each integral flanged wear sleeve may comprise a right circular hollow cylindrical body portion, which may be interiorly sized to be retained on one of the pins and externally sized to be retained in one of the pin receptive bores, and a flange portion may radiate from one end of the cylindrical body portion.

A gimbal joint may employ a plurality of wear sleeves, each disposed between a pin or pin receptive bore of a first structure and a corresponding bore or pin of a second structure and between another pin or bore of the second structure and a corresponding bore or pin of a third structure. Each of these structures may be adapted to rotate in a single plane, with one structure adapted to also tilt about a first axis, and one other structure adapted to tilt about a second axis. Each integral flanged wear sleeve may comprise a right circular hollow cylindrical body portion, which may be interiorly sized to be retained on one of the pins and externally sized to be retained in one of the pin receptive bores, and a flange portion may radiate from one end of the cylindrical body portion.

A gimbal joint may employ a plurality of wear sleeves, each disposed between a pin or pin receptive bore of a first structure and a corresponding bore or pin of a second structure and between another pin or bore of the first structure and a corresponding bore or pin of a third structure. Each of these structures may be adapted to rotate in a single plane, with one structure adapted to also tilt about a first axis, and one other structure adapted to tilt about a second axis. Each integral flanged wear sleeve may comprise a right circular hollow cylindrical body portion, which may be interiorly sized to be retained on one of the pins and externally sized to be retained in one of the pin receptive bores, and a flange portion may radiate from one end of the cylindrical body portion.