Abstract: One example includes a passive rotor pitch control system. The system includes a counterweights that are each associated with one of a respective plurality of rotors and can be arranged to have a center of mass configured to provide a pitch torque about a pitch axis associated with the respective one of the rotors in response to rotation of the rotors about a rotation axis. The system also includes a spring forcer comprising a pitch rod and a spring configured to provide a spring force on the pitch rod. The system further includes a pitch change assembly coupled to the counterweights and the pitch rod. The pitch change assembly can be configured to rotate a pitch of each of the rotors from a first pitch state to a second pitch state in response to a sum of pitch torques associated with the counterweights being greater than the spring force.

Abstract: One example includes a passive rotor pitch control system. The system includes a counterweights that are each associated with one of a respective plurality of rotors and can be arranged to have a center of mass configured to provide a pitch torque about a pitch axis associated with the respective one of the rotors in response to rotation of the rotors about a rotation axis. The system also includes a spring forcer comprising a pitch rod and a spring configured to provide a spring force on the pitch rod. The system further includes a pitch change assembly coupled to the counterweights and the pitch rod. The pitch change assembly can be configured to rotate a pitch of each of the rotors from a first pitch state to a second pitch state in response to a sum of pitch torques associated with the counterweights being greater than the spring force.

Abstract: A structure and a method of constructing a root joint and blade retention mechanism of a composite airfoil of a propulsor blade is presented. The retention assembly includes an inner sleeve configured to retain a root area of the composite propulsor blade. The inner sleeve is fixedly attached to an inner surface of the root area by a resin transfer molding process. An outer sleeve is bonded to an outer surface of the composite propulsor blade after the completion of the resin transfer molding process. At least one bearing assembly is disposed within an annular groove of the outer sleeve. The bearing assembly rotatably couples the propulsor blade and the retention assembly to a hub assembly.

Abstract: A support structure for a propulsor blade includes at least one sleeve configured to support a root portion of the propulsor blade, the at least one sleeve fixedly attached to a surface of the root portion. The support structure also includes a preloading component configured to apply a residual compressive force to the at least one sleeve and the root portion of the propulsor blade, the residual compressive force configured to maintain an attachment of the at least one sleeve to the root portion. The propulsor blade and root portion may incorporate composite structural materials. The support structure and/or the preloading component increases the high cycle fatigue strength and bending capacity of blade retention assemblies (including, e.g., composite-to-metal joints) when subjected to high cycle bending loads under reduced centrifugal load conditions, thereby making further reductions in the size and weight of blade retention assemblies feasible.

Abstract: A support structure for a propulsor blade includes at least one sleeve configured to support a root portion of the propulsor blade, the at least one sleeve fixedly attached to a surface of the root portion. The support structure also includes a preloading component configured to apply a residual compressive force to the at least one sleeve and the root portion of the propulsor blade, the residual compressive force configured to maintain an attachment of the at least one sleeve to the root portion. The propulsor blade and root portion may incorporate composite structural materials. The support structure and/or the preloading component increases the high cycle fatigue strength and bending capacity of blade retention assemblies (including, e.g., composite-to-metal joints) when subjected to high cycle bending loads under reduced centrifugal load conditions, thereby making further reductions in the size and weight of blade retention assemblies feasible.

Abstract: A system for providing variable pitch to a rotor blade of an aircraft engine includes a rotatable hub; at least one blade mounted on the rotatable hub; a gear mechanism operably connected to the rotatable hub; a timing ring rotatably and operably connected to the gear mechanism; and a pitch arm operably connecting the timing ring and the at least one blade mounted on the rotatable hub. In the operation of the system, the gear mechanism facilitates the rotation of the timing ring to vary the pitch of the at least one blade mounted on the rotatable hub.

Abstract: A system for providing support to a fan blade of an aircraft engine includes a rotatable hub; a cradle pivotally mounted on the rotatable hub, the cradle comprising a flexible member and an adjacently positioned support member; a fan blade attached at a first end thereof to the cradle such that the flexible member engages a first surface of the fan blade at the first end of the fan blade and the support member engages a second opposing surface of the fan blade at the first end of the fan blade and such that the flexible member and the support member provide support to the fan blade relative to the rotatable hub; and means for rotating the cradle relative to the rotatable hub to vary the pitch of the fan blade. The system may include spherical support surfaces located on sides of the cradle.

Abstract: A system for providing variable pitch to a rotor blade of an aircraft engine includes a rotatable hub; at least one blade mounted on the rotatable hub; a gear mechanism operably connected to the rotatable hub; a timing ring rotatably and operably connected to the gear mechanism; and a pitch arm operably connecting the timing ring and the at least one blade mounted on the rotatable hub. In the operation of the system, the gear mechanism facilitates the rotation of the timing ring to vary the pitch of the at least one blade mounted on the rotatable hub.