Abstract: A semi-articulated stiff-in-plane (SASTIP) rotor hub is provided. The hub includes a cylindrical composite shell (12). A plurality of flexure mount assemblies (16) are positioned around the periphery of the hub shell. Each flexure mount assembly includes both an upper and a lower flexure (64), (66). The outboard ends of the upper and lower flexures attach to an outboard bearing support (34). The inboard end of each flexure is maintained within first and second clamp plates (76), (78) that are mounted within hub flexure openings (38), (40). The flexure clamp plates (76), (78) additionally attach circumferentially to annular CF rings (24), (26), (28), (30) positioned within the hub shell. A blade shaft (14) extends through the outboard bearing (72) and connects to a spindle. The spindle is supported by a spherical bearing that is mounted within the hub shell (12) at a circular spindle hole.

Abstract: A rotor hub for a rotary wing aircraft is described which allows the use of more than three blades on the rotor head while providing all of the required functional features. The rotor head is constructed using a central barrel to which is attached a plurality of blade attachment points on its exterior surface. The pitch arm actuating points are located inside of the hub barrel, extending from the outer surface into the hub barrel through arcuate slots in the barrel. The hub is particularly adapted for use with tilt rotor rotary wing aircraft and provides a negative Delta 3 blade pitch input in response to wind gusts and abrupt pilot control inputs.

Abstract: A tail rotor for a rotary wing aircraft is located in a laterally directed duct located at the end of a tail cone extending rearward from the aircraft cabin and at the base of an empennage extending upward from the duct. The rotor includes a rotor shaft driveably connected to a power source, a rotor hub connected to the rotor shaft, a rotating control shaft, a stationary control shaft, and an actuator connected to the stationary control shaft for moving the rotating control shaft axially. The rotor hub includes rotor arms each supporting a pitch shaft-blade spar assembly for pivotable movement about a pitch axis. A pitch beam supports flexures, each connected to a pitch arm offset laterally from the associated pitch axis. The flexures driveably connect the pitch arms to the pitch beam and transmit pitch control motion to the blades as the pitch beam moves along the rotor axis. Pitch bearings, on which the pitch shafts turn about the pitch axes, are supported on a rotor hub shell fixed to the rotor hub.

Abstract: A tail rotor for a rotary wing aircraft is located in a laterally directed duct located at the end of a tail cone extending rearward from the aircraft cabin and at the base of an empennage extending upward from the duct. The rotor includes a rotor shaft driveably connected to a power source, a rotor hub connected to the rotor shaft, a rotating control shaft, a stationary control shaft, and an actuator connected to the stationary control shaft for moving the rotating control shaft axially. The rotor hub includes rotor arms each supporting a pitch shaft for pivotable movement about a pitch axis. Each pitch shaft is adapted to support a rotor blade so that its angle of attack changes with movement of the pitch shafts. A pitch beam, located adjacent the rotor hub, supports flexure members, each connected to a pitch shaft eccentric of its pitch axis.

Abstract: A rotor hub system for a helicopter is fabricated predominately of composite material. The flap hinge, pitch hinge and lead-lag hinge contain elastomeric bearings and one step blade folding in either the forward or aft direction using the same drive system is employed. The rotor hub includes closed loop straps which define generally opposed lugs of the flap hinge, and the pitch housing includes a pair of closed loop straps which define the lugs of the lead-lag hinge and a lug of the flap hinge. The use of composite materials as the predominant material of the rotor hub and the pitch housing results in a highly load redundant structure permitting a reduction in size and number of parts, a reduction in drag, and an increase in reliability and safety.

Abstract: A rotor hub system for a helicopter in which the rotor hub and pitch housing are fabricated predominately of composite material, the flap hinge, pitch hinge and lead-lag hinge contain elastomeric bearings and one step blade folding in either the forward or aft direction using the same drive system. The rotor hub includes closed loop straps which define generally opposed lugs of the flap hinge, and the pitch housing includes a pair of closed loop straps which define the lugs of the lead-lag hinge and a lug of the flap hinge. The use of composite materials as the predominant material of the rotor hub and the pitch housing results in a highly load redundant structure permitting a reduction in size and number of parts, a reduction in drag, and an increase in reliability and safety.

Abstract: A rotor hub system for a helicopter in which the rotor hub and pitch housing are fabricated predominately of composite material, the flap hinge, pitch hinge and lead-lag hinge contain elastomeric bearings and one step blade folding in either the forward or aft direction using the same drive system. The rotor hub includes closed loop straps which define generally opposed lugs of the flap hinge, and the pitch housing includes a pair of closed loop straps which define the lugs of the lead-lag hinge and a lug of the flap hinge. The use of composite materials as the predominant material of the rotor hub and the pitch housing results in a highly load redundant structure permitting a reduction in size and number of parts, a reduction in drag, and an increase in reliability and safety.

Abstract: A rotor hub system for a helicopter in which the rotor hub and pitch housing are fabricated predominately of composite material, the flap hinge, pitch hinge and lead-lag hinge contain elastomeric bearings and one step blade folding in either the forward or aft direction using the same drive system. The rotor hub includes closed loop straps which define generally opposed lugs of the flap hinge, and the pitch housing includes a pair of closed loop straps which define the lugs of the lead-lag hinge and a lug of the flap hinge. The use of composite materials as the predominant material of the rotor hub and the pitch housing results in a highly load redundant structure permitting a reduction in size and number of parts, a reduction in drag, and an increase in reliability and safety.

Abstract: A rotor control system for a helicopter in which the conventional swashplate is eliminated and the rotor hub is integrated to include an actuator for each rotor blade. Two arrangements are employed, each of which utilizes a hydraulic circuit. One arrangement is a hydromechanical arrangement with stick control, while the other arrangement is an electro-hydraulic fly by wire arrangement. The latter does not employ a swashplate, while the former employs a modified swashplate. The controls, like the actuators, are mounted in the rotor hub, and the hydraulic lines and fiber optics pass through the rotor drive shaft to the rotor hub.

Abstract: A semi-articulated flexstrap for use in connecting a rotor blade to the hub of a helicopter rotor is disclosed. The flexstrap includes a series of straps which alternatingly crisscross at a point between the blade and hub. The straps are substantially parallel to the plane of rotation of the rotor at the crossover point and unrestrained so as to permit relative movement between the straps. The relative movement of the straps of articulation of the flexstrap in the plane of rotation of the rotor permits lead lag motion of the rotor blade to occur.