A propeller blade arrangement comprising a propeller blade attached to and rotatable with a hub, via a retention bearing, the blade being rotatable about a center line of the blade, the retention bearing configured to tilt the blade such that its center line is tilted with respect to the hub.

A propeller includes a blade free to rotate. A first stop is positioned to mechanically engage one or both of a first portion of the blade and a first structure coupled to the blade when the blade is in a first position at a first end of the rotational range of motion. A second stop is positioned to mechanically engage one or both of a second portion of the blade and a second structure coupled to the blade when the blade is in a second position at a second end of the defined rotational range. The blade rotates to the first position against the first stop when the propeller is rotated in a first direction and to the second position against the second stop when the propeller is rotated in a second direction.

A blade-pitch change mechanism includes a motor comprising a rotating motor shaft and a housing, a solenoid coupled to a first end of the rotating motor shaft and to the housing, and a hub coupled with a second end of the rotating motor shaft. The hub includes a cylindrical puck having formed therein a gated castellated groove and connected to the second end of the rotating motor shaft and a cylindrical blade-pitch hub selectively couplable with the cylindrical puck via a plurality of drive pins and having formed therein a blade-pitch adjustment groove.

A blade-pitch change mechanism includes a motor comprising a rotating motor shaft and a housing, a solenoid coupled to a first end of the rotating motor shaft and to the housing, and a hub coupled with a second end of the rotating motor shaft. The hub includes a cylindrical puck having formed therein a gated castellated groove and connected to the second end of the rotating motor shaft and a cylindrical blade-pitch hub selectively couplable with the cylindrical puck via a plurality of drive pins and having formed therein a blade-pitch adjustment groove.

A hinged propeller comprising a hub and one or more blades is disclosed. In various embodiments, a blade is connected to the hub via a hinge, wherein at least a substantial part of the blade has a longitudinal axis that is substantially parallel to a line extending radially from a center of the hub, and wherein the hinge has an axis of hinge rotation that is oriented at a non-zero acute angle to a line that is perpendicular, in a plane of rotation of the hub, to said longitudinal axis.

A hinged propeller comprising a hub and one or more blades is disclosed. In various embodiments, a blade is connected to the hub via a hinge, wherein at least a substantial part of the blade has a longitudinal axis that is substantially parallel to a line extending radially from a center of the hub, and wherein the hinge has an axis of hinge rotation that is oriented at a non-zero acute angle to a line that is perpendicular, in a plane of rotation of the hub, to said longitudinal axis.

A method of providing torque protection and/or thrust protection for the or each propeller of a hybrid helicopter. The hybrid helicopter includes a control system connected to the blades of each propeller and a thrust control configured to generate an order for modifying a pitch of the blades, which order is transmitted to the control system, the propeller(s) being driven in rotation by a mechanical transmission system of the hybrid helicopter. The method includes a step of having the control system keep the pitch of the blades of a propeller within at least one control envelope relating to a thrust generated by the propeller or to a torque exerted in the mechanical transmission system. In this way, the pitch of the blades of each propeller is kept between a lower limit and an upper limit of the control envelope.

A method of providing torque protection and/or thrust protection for the or each propeller of a hybrid helicopter. The hybrid helicopter includes a control system connected to the blades of each propeller and a thrust control configured to generate an order for modifying a pitch of the blades, which order is transmitted to the control system, the propeller(s) being driven in rotation by a mechanical transmission system of the hybrid helicopter. The method includes a step of having the control system keep the pitch of the blades of a propeller within at least one control envelope relating to a thrust generated by the propeller or to a torque exerted in the mechanical transmission system. In this way, the pitch of the blades of each propeller is kept between a lower limit and an upper limit of the control envelope.

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.

An offset blade of a propeller varies the blade pitch according to in-flight conditions in order to maximize the performance and efficiency of the propeller. As the propeller begins to rotate, upward thrust forces and lateral centrifugal forces are generated on the blade. The balance between the thrust and centrifugal forces determines the blade pitch. At rest, the blade pitch is minimized whereas when in-flight, the blade pitch of the propeller blade is maximized. The blade is coupled with a rotor hub through a connector that determines the maximum and minimum blade pitches of the blade. Furthermore, the connector reduces blade pitch oscillations that often occur in flight.