Abstract: A rotor system vibration absorber for use with a helicopter of other rotorcraft is disclosed in which spring forces are provided by a plurality of elongated rods arranged in a selected pattern. The rods are coupled at one end to a fixed base that is coupled to a rotor hub, and at the other end to a tuning weight.

Abstract: The subject tiltrotor aircraft has three modes of operation: airplane mode, helicopter mode, and transition mode. A tilting mast, which transitions the aircraft between airplane mode and helicopter mode, is controlled by systems that allow selective movement of the rotor blades between the flight modes. A hub couples the rotor blades to the tilting mast such that torque and thrust are transferred, while allowing rotor thrust vector tilting. A main swash plate controls rotor thrust vector direction. Pitch horns are coupled to the rotor blades and the main swash plate via pitch links such that swash plate inputs are communicated to the rotor blades. The pitch links are coupled at “delta-3” values that are not optimum. A feedback swash plate and feedback links receive disk tilting inputs from the rotor blades, and supply inputs to the main swash plate, which compensates for the less than optimum delta-3 coupling.

Abstract: An aircraft with a tilt rotor assembly comprising a craft body, a plurality of rotor blades which are subject to three modes of flight operation, a tilting mast coupling the plurality of rotor blades to the craft body and for selectively moving the plurality of rotor blades between the three modes of flight operation, a hub coupling the plurality of rotor blades to the tilting mast in a manner which transfers torque and thrust while allowing tilting of a rotor thrust vector, a main swashplate for tilting in response to operator input to control the direction of the rotor thrust vector, a plurality of pitch horns, each mechanically coupled to a particular one of the plurality of rotor blades and to the main swashplate, for communicating swashplate input to each of the plurality of rotor blades, a plurality of links coupling the main swashplate to the plurality of pitch horns, wherein each of the plurality of pitch horns is mechanically coupled to a particular one of the plurality of rotor blades by one of the

Abstract: Rotor blade stowing system for stowing rotor blades that conserves storage space without adding significant weight or cost to the aircraft. The system includes a rotary actuator disposed on a blade grip member. A rotor blade is pivotally connected to the blade grip member. The rotary actuator is operably coupled to a blade pivoting cam and a locking cam. The system includes a cam follower linkage which has a first end which includes a blade pivoting cam follower and a locking cam follower and a second end. The blade pivoting cam follower follows the blade pivoting cam. The locking cam follower follows the locking cam. The second end of the cam follower linkage is coupled to the blade grip member. The system includes a shaft rotatably coupled to the blade grip member, a locking linkage bell crank operably coupled to the shaft, a delay cam coupled to the blade grip member, and a locking linkage idler operably coupled to the locking linkage bell crank.

Abstract: A vibration absorber having a mass member which when static is supported by in-plane springs spaced apart from a base plate, top plate and spring retaining structures. The mass member has a bumper surface for contacting a motion limiter in the base plate. The mass member, base plate and top plate can have a passageway through the axis. The vibration absorber can be tuned by proper selection of the springs, degree of precompression and the variation of the amount of mass by the addition or removal of mass tuning weights.

Abstract: An improved feathering flexure for a helicopter rotor system yoke includes, in transverse cross section, a relatively thin central web and six relatively thin flanges. Three flanges extend from each of the web's two edges, and the flanges lie in planes which are approximately radial relative to the neutral feathering axis of the feathering flexure. The feathering flexure is constructed of fiberglass material embedded in a polymer matrix. The web's fiberglass material in the web is bias material, that is, material whose glass fibers are oriented at plus or minus 45 degrees relative to the yoke's spanwise axis. In transverse cross section, each of the flanges includes two unidirectional belts disposed on either side of a bias pack. The glass fibers in the unidirectional belts are oriented parallel to the yoke's spanwise axis. The fiberglass material in the bias packs is bias material.

Abstract: A composite rotor blade comprising an outboard portion defining an airfoil surface, an inboard portion defining an end tang having a mounting section and an extension lug section. The mounting section of the end tang having at least one mounting aperture with an axis parallel to the chordline of the airfoil for mounting of the blade, and the extension lug section having at least one extension lug extending inboard of the mounting aperture to provide a lever surface for interaction with suitable mounting mechanisms.

Abstract: Folding and folding locking apparatus for rotor blades that includes a power actuator for rotating the blades and locking means for securing the blade in the deployed position and securing the blades against rotation of the pitch angle during and when the blades are folded. The apparatus also provides for the complete fairing of the blades at their connections with the rotary drive hub and provides a powered door in the fairing that can be opened and closed to permit the quick and easy folding and redeployment of the blades.

Abstract: This invention relates to helicopter rotors and more particularly to rotor mounting involving a composite fiber-reinforced unitary yoke with resilient inplane restraints.

Abstract: A helicopter tail rotor structure includes a thin, flat, tension-bearing strap of fibers extending spanwise, and is to be centrally secured by a hub to a helicopter tail mast. Flex sections are formed inboard of substantially equally divided portions of said fibers which extend as top and bottom blade spars from the outboard margins of the flex sections. Preferably, the planes of the flex sections and the planes of the spars are oriented at predetermined nose-up twist angles, one relative to the other.

Abstract: A tail rotor blade for a helicopter has a core 22 whose shape defines the trailing portions of the blade. Core 22 is adhered to upper 20 and lower 21 metallic skins which extend within and are adhered to the inner surfaces at the trailing edge of a metallic nose spar 10. A pair of straps 30, 31 of unidirectional fiberglass strands extend spanwise and are adhered to the inner surface of the leading edges of the skins 20, 21 and the outer leading surfaces of the core 22 as to span chordwise the regions of the joints between nose spar 10 and skins 20, 21.

Abstract: A helicopter rotor hub assembly (10) in which a blade grip (30) extends inboard of a yoke (14) and transfers centrifugal forces to the yoke (14) through a spherical elastomeric bearing (38). Pitch change of the grip (30) and blade (32) is accommodated by the spherical elastomeric bearing (38) which also acts as the pivot point for lead-lag motion of the blade (32) and grip (30). A lead-lag damper (22) is located inboard of the elastomeric bearing (38) and is connected between one end of the grip (30) spaced away from the lead-lag pivot and the yoke (14) for damping the lead-lag motion between the grip (30) and yoke (14).

Abstract: An apparatus is disclosed for folding a helicopter rotor blade (16) for storage. The blade (16) is secured to a grip (12) by blade bolts (18, 20) which are locked in place by a latch plate (22). Each bolt (18, 20) has an annular groove (30, 31) in which is mated a corresponding aperture (42, 46) in the latch plate (22). To fold the blade (16) the latch plate (22) is translated against the tension of spring (24) to expose a blade bolt (18) to an enlarged aperture (40). This bolt (18) can then be removed to permit pivoting of the blade (16) about the remaining bolt (20). To further secure the latch plate (22), a cap (54) is provided to lock the latch plate (22) to the blade bolt (18).

Abstract: A helicopter main rotor blade having a metallic nose spar extending the length of the leading edge of the blade and a trailing edge skin attached to the nose spar. A closure channel fixed within the nose spar extends the length thereof with unidirectional fiberglass material fixed to and extending along the length of the closure channel. A bushing on the inboard end of the blade preferably is attached both to the nose spar and the fiberglass bands for transfer of centrifugal forces in the blade to a grip.

Abstract: A composite rotor blade has a nose spar of fiber reinforced plastic with the fibers extending spanwise the length of the spar and at the root encircling a transverse hub attachment structure with the spar provided with a tubular inner liner of cross ply filament wound fiberglass forming a closure for the nose spar with a blad afterbody structure including skins for integrating the afterbody with the nose spar and liner. Preferably the spar has an inner liner and an outer liner both of cross ply filament wound fiberglass in multi layers. The blade afterbody structure includes honeycomb filler having cells extending in the direction of blade thickness.

Abstract: A grip-yoke assembly for attaching a helicopter blade to the mast of the helicopter rotor having a conventional primary coupling to carry the centrifugal loads and a redundant path operative should the primary coupling fail to insure continued operability of the blade. In one embodiment, the redundant load path has a bearing surface formed on the inboard end of the grip and a corresponding thrust bearing mounted on an inboard yoke fitting for engagement with the bearing surface upon failure of the coupling. In an alternative embodiment, a bearing surface is formed on an outboard grip fitting and a corresponding thrust bearing is supported on the yoke outboard of the grip fitting.