Abstract: An apparatus may comprise a housing, a first member, and a second member. The housing may have a first end, a second end, a first side, a second side, an opening located in the first end, and a passage extending from the opening. The first member may extend from the first side. The first member may have a first channel in communication with the passage and the channel has a first center axis. The second member may extend from the first side. The second member may have a second channel in communication with the passage and the second channel has a second center axis substantially aligned with the center axis of the channel in the first member.

Abstract: A propeller assembly includes a rotatable hub having a center metal hub portion and an outer composite hub portion. A set of composite propeller blades are mounted for pitch control rotation on the hub by a set of dry bearings.

Abstract: Embodiments of a bi-axial compliant bearing assembly and methods of assembling the bi-axial compliant bearing assembly are disclosed. A bi-axial compliant bearing assembly employs a transition bearing race. The transition bearing race comprises a cylindrical surface. The cylindrical surface is configured to rotatably engage a rotational bearing element and to slidably engage the rotational bearing element along an axis. The transition bearing race also includes a spherically-compliant surface. The spherically-compliant surface is configured to engage a spherically-compliant element and to enable the spherically-compliant element to rotate transversely to the axis.

Abstract: A propeller assembly includes a rotatable hub having a center metal hub portion and an outer composite hub portion. A set of composite propeller blades are mounted for pitch control rotation on the hub by a set of dry bearings.

Abstract: A sculpted throat spool of a tension-torsion strap assembly is disclosed. Using the sculpted throat spool minimizes the stress riser typically present at the edge of the spool when a tension-torsion strap is articulated.

Abstract: Described herein is a rigid rotor assembly configured to allow rotation of helicopter rotor blades attached to the rigid rotor assembly from a deployed position to a stowed position. The rigid rotor assembly includes a base including a shaft extending therethrough, a first spindle configured to engage the shaft, and a second spindle configured for placement onto the shaft. The second spindle is operable to maintain a first position with respect to the first spindle via an attachment mechanism therebetween, the second spindle further operable to maintain a second position with respect to the first spindle via the attachment mechanism.

Abstract: A method for connecting a tension-torsion strap. The method includes sliding a sleeve into an arm of a hub; aligning holes in the sleeve with holes in the hub; installing a bushing in each aligned hole in the sleeve; sliding a first end of the tension-torsion strap through the sleeve; and placing a pin through the bushings and the tension-torsion strap.

Abstract: An apparatus may comprise a housing, a first member, and a second member. The housing may have a first end, a second end, a first side, a second side, an opening located in the first end, and a passage extending from the opening. The first member may extend from the first side. The first member may have a first channel in communication with the passage and the channel has a first center axis. The second member may extend from the first side. The second member may have a second channel in communication with the passage and the second channel has a second center axis substantially aligned with the center axis of the channel in the first member.

Abstract: A method of sintering a 17-4PH alloy powder and a sintered 17-4PH sintered part are disclosed. The part is formed by selective laser sintering a 17-4PH alloy powder and binder mixture to form a green part that is sintered to form a part having a substantially pure martensitic structure. The metal powder includes boron. The sintered part may be further processed by shot peening to improve crack resistance.

Abstract: A method of sintering a 17-4PH alloy powder and a sintered 17-4PH sintered part are disclosed. The part is formed by selective laser sintering a 17-4PH alloy powder and binder mixture to form a green part that is sintered to form a part having a substantially pure martensitic structure. The metal powder includes boron. The sintered part may be further processed by shot peening to improve crack resistance.

Abstract: A tail rotor hub system and methods are disclosed. In one embodiment, the system includes a helicopter fuselage connected to a tail rotor assembly that holds tail blades. The assembly includes an elongated tail rotor housing and an elongated blade root fitting that rotates within the housing. A tension torsion strap is connected at one end to the housing and is connected at its other end to the blade root fitting to hold the blade root fitting in the housing when the housing rotates. Coupled between outside walls of the blade root fitting and inside walls of the housing are self lubricating bearings to enable the blade root fitting to rotate within the housing to change the pitch of the tail blades.

Abstract: In an exemplary variable area nozzle, a fixed duct section has an inlet and an outlet oriented approximately perpendicular to the inlet. A controllable nozzle member is disposed adjacent the outlet of the fixed duct section. The controllable nozzle member has an area that is adjustable to maintain a substantially constant nozzle pressure ratio. The controllable nozzle member may include first and second flap doors hinged and pivotable in opposite directions between an open position and a closed position and that also may be hinged and pivotable in a same direction so thrust from gas exiting the nozzle is vectorable. When disposed in rotor tips of an aircraft capable of rotary wing flight and fixed wing flight, the variable area nozzle may maintain a substantially constant nozzle pressure ratio near an optimized nozzle pressure ratio as the aircraft transitions from rotary wing flight to fixed wing flight.

Abstract: Embodiments of a bi-axial compliant bearing assembly and methods of assembling the bi-axial compliant bearing assembly are disclosed. A bi-axial compliant bearing assembly employs a transition bearing race. The transition bearing race comprises a cylindrical surface. The cylindrical surface is configured to rotatably engage a rotational bearing element and to slidably engage the rotational bearing element along an axis. The transition bearing race also includes a spherically-compliant surface. The spherically-compliant surface is configured to engage a spherically-compliant element and to enable the spherically-compliant element to rotate transversely to the axis.

Abstract: Described herein is a rigid rotor assembly configured to allow rotation of helicopter rotor blades attached to the rigid rotor assembly from a deployed position to a stowed position. The rigid rotor assembly includes a base including a shaft extending therethrough, a first spindle configured to engage the shaft, and a second spindle configured for placement onto the shaft. The second spindle is operable to maintain a first position with respect to the first spindle via an attachment mechanism therebetween, the second spindle further operable to maintain a second position with respect to the first spindle via the attachment mechanism.

Abstract: An apparatus may comprise a housing, a first member, and a second member. The housing may have a first end, a second end, a first side, a second side, an opening located in the first end, and a passage extending from the opening. The first member may extend from the first side. The first member may have a first channel in communication with the passage and the channel has a first center axis. The second member may extend from the first side. The second member may have a second channel in communication with the passage and the second channel has a second center axis substantially aligned with the center axis of the channel in the first member.

Abstract: A set of analytic forms provide empirical data used to determine the material properties of a part following its fabrication. Multiple of families of the forms are identically processed to provide a variety of data, including the reaction of the part material to compression, tension and bending stresses. The forms in each family have a structural feature that singularizes the directional effect of gravity on a test cross section of the material. The dimensions of the test cross section progressively vary within each family so that data can be generated for multiple levels of stress.

Abstract: A sculpted throat spool of a tension-torsion strap assembly is disclosed. Using the sculpted throat spool minimizes the stress riser typically present at the edge of the spool when a tension-torsion strap is articulated.

Abstract: In an exemplary variable area nozzle, a fixed duct section has an inlet and an outlet oriented approximately perpendicular to the inlet. A controllable nozzle member is disposed adjacent the outlet of the fixed duct section. The controllable nozzle member has an area that is adjustable to maintain a substantially constant nozzle pressure ratio. The controllable nozzle member may include first and second flap doors hinged and pivotable in opposite directions between an open position and a closed position and that also may be hinged and pivotable in a same direction so thrust from gas exiting the nozzle is vectorable. When disposed in rotor tips of an aircraft capable of rotary wing flight and fixed wing flight, the variable area nozzle may maintain a substantially constant nozzle pressure ratio near an optimized nozzle pressure ratio as the aircraft transitions from rotary wing flight to fixed wing flight.

Abstract: A method of sintering a 17-4PH alloy powder and a sintered 17-4PH sintered part are disclosed. The part is formed by selective laser sintering a 17-4PH alloy powder and binder mixture to form a green part that is sintered to form a part having a substantially pure martensitic structure. The metal powder includes boron. The sintered part may be further processed by shot peening to improve crack resistance.

Abstract: A tail rotor hub system and methods are disclosed. In one embodiment, the system includes a helicopter fuselage connected to a tail rotor assembly that holds tail blades. The assembly includes an elongated tail rotor housing and an elongated blade root fitting that rotates within the housing. A tension torsion strap is connected at one end to the housing and is connected at its other end to the blade root fitting to hold the blade root fitting in the housing when the housing rotates. Coupled between outside walls of the blade root fitting and inside walls of the housing are self lubricating bearings to enable the blade root fitting to rotate within the housing to change the pitch of the tail blades.