Abstract: Blade fold hinge units are attachable between each helicopter blade and its hub attachment point, while maintaining continuity of mechanical connection of each blade to its hub portion. A two portion hinge unit has a first portion for blade attachment and a second portion for hub attachment. The first and second portions are hinged via a transverse pin to enable blade drooping downward, before or after a blade is pivoted to an aft position for helicopter storage or shipment. Upon aft pivoting of a blade, undesired further pivoting or knuckling of the hinge unit relative to the hub is prevented by addition of a lock link. After blade folding, the blades may be suitably fixed in position adjacent the aft portion of the helicopter body.

Abstract: An edge member for use on a composite flexure having an exposed edge surface. The edge member includes an innermost composite ply attached to the edge surface, an outermost composite ply attached to the innermost composite ply, and at least one interior composite ply disposed between the innermost composite ply and the outermost composite ply.

Abstract: A prop rotor hub includes a constant velocity joint in the same plane as a prop blade yoke. Torque is transmitted from a shaft to the blades through the CV joint, hub plates attached to the CV joint, and the yoke, which is attached to the hub plates. Providing all elements in a substantially planar arrangement results in a hub assembly which has significantly less height than a traditional design. The hub itself is in-plane with the yoke, resulting in a more efficient torque transmission from the mast to the rotor.

Abstract: The rotating plate of the system is fixed in rotation with the rotor by a driver with two rigid driving tracks extending axially and diametrically opposite in being fixed in rotation with the rotor. Each track engages with one of two driving fingers fixed in rotation with the rotating plate and diametrically opposite on this latter. Each track has two webs between which one finger is engaged with the result of following on this track a rectilinear trajectory, parallel to the rotor axis and a circular arc trajectory centerd on this axis, respectively in the case of change of collective and cyclic pitch.

Abstract: A magnetic particle damper apparatus is provided for damping motion between two relatively movable members. The damper apparatus comprises first and second conductor members each attachable to one of the relatively movable members. The conductor members are disposed with confronting surfaces having a gap therebetween filled with a quantity of magnetic particles. A magnetic element is attached to one of the conductor members, producing magnetic flux which is substantially confined to a magnetic flux path defined by relatively magnetically permeable regions and relatively magnetically non-permeable regions of the conductor members to flow across the gap and through the magnetic particles. The magnetic field causes the magnetic particles along the flux path to adhere to one another and to the confronting surfaces of the conductor members producing a force opposing relative motion between said movable members and dissipating energy when the conductor members move relative to one another.

Abstract: A helicopter gimbal rotor arrangement includes a drive shaft with a rotor hub, a rotor blade holder arrangement, and a coupling membrane for transmitting the rotational drive moment from the rotor hub to the rotor blade holder arrangement. The coupling membrane includes a plate element made up of a plurality of concentric rings that are spaced apart radially by annular gaps and are connected to each other by respective connecting webs spanning across the gaps. This plate element as the coupling membrane provides torsional stiffness combined with bending flexibility to allow tilting motions of the rotor blade holder arrangement relative to the rotor hub. Plural plate elements connected in parallel provide a redundant fail-safe arrangement, while plural plate elements connected in series achieve increased flexibility for out-of-plane tilting.

Abstract: The swash-plates are oscillating mounted by the non-rotating plate on a central ball joint sliding axially around a guide fixed to the structure and on which the ball joint is locked from rotation by internal splines engaging with external splines of the guide. Two parts slide on diametrically opposite raised sectors on the ball joint, and the non-rotating plate pivots on trunnions of the parts around one of two perpendicular axes the other of which is the one around which the parts pivot and which is perpendicular to the rotor axis.

Abstract: The swash-plates are oscillating mounted by the non-rotating plate on a central ball joint sliding axially around a guide fixed to the structure and on which the ball joint is locked from rotation by internal splines engaging external splines of the guide. Two cotters slide in diametrically opposite grooves in the external face of the ball joint, and the non-rotating plate pivots on trunnions of the cotters around one of two perpendicular axes the other of which an axis around which the cotters pivot and which is perpendicular to the rotor axis.

Abstract: The rotating and non-rotating swash-plates are guided in axial translation and in tilting on the rotor axis by two non-rotating pillars and slides provided with runners with a cylindrical external face permanently tangentially engaged and sliding against the internal faces of the pillars, the slides bearing two diametrically opposite trunnions allowing the pivoting of the non-rotating plate around a diametrical axis, whereas the sliding and pivoting of the runners on the pillars guide the pivoting of the non-rotating plate around a second diametrical axis, which is the axis of the cylindrical face of the runners.

Abstract: The rotating and non-rotating swash-plates are guided in axial translation and in tilting on the rotor axis by a non-rotating axial guide arrangement, such as two pillars, and slides on each of which slides one of two pads carrying diametrically opposite trunnions, enabling the pivoting of the non-rotating plate around a first diametrical axis, whereas the sliding movements of the pads on the slides guide the pivoting movements of the non-rotating plate around a second diametrical axis perpendicular to the rotor axis and first diametrical axis, and which is the axis of the cylindrical face of the slides.

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 multi-blade rotor arrangement free of flapping hinges, for a rotary wing aircraft, includes a rotor head plate (2) made of fiber-reinforced composite material. The head plate (2) includes a plurality of blade connection arms (4) that are elastically flexibly bendable in the blade flapping direction, and at least one plate segment (16, 18) that holds each blade connection arm on two sides thereof radially spaced away from the rotor center in a manner that allows elastic bending in the blade flapping direction. The plate segment is rigidly connected to the rotor mast (122, 222) at mounting locations (20) that are offset in the circumferential direction from the blade connection arms. In this manner, the elastically yielding flapping connection between the rotor blades and the rotor mast is provided by both the elastic bending of the blade connection arms and the elastic deformation of the plate segment portions between the blade connection arms and the mast mounting locations.

Abstract: The non-rotating plate of the device is stopped from rotating around the rotor axis by a stop arm with at least one rigid stop track extending substantially axially and secured to the structure of the rotor aircraft. The track works together with a stop pin, integral with the non-rotating plate to stop the latter from rotating. The track has two flanges between which the pin is engaged so as to follow on this track a straight trajectory, parallel to the rotor axis and a circular arc trajectory centered on this axis, in the case of variation in the collective and cyclic pitch respectively. The stop pin includes a pad sliding between the two flanges of a slide constituting the said track and hinged around its fastening axis on the non-rotating plate.

Abstract: A monolithic structural member (10) operative for reacting steady and vibratory bending moment loads M about an applied loads axis X and having a specially configured cross-sectional configuration for providing improved flaw tolerance. The cross-sectional configuration (10) includes a central connecting element (18) and at least one pair of structural ribs (14a, 14b) being integrally formed with the central connecting element (18) and projecting outwardly thereof. The structural ribs (14a, 14b) are, furthermore disposed in the tensile field produced by the steady portion of the bending moment loads M and are proximal to the centroid C.sub.T of the cross-section (10). The cross-sectional configuration (10) defined by the structural ribs and connecting element produces a partial inertia ratio I.sub.X /I.sub.Y greater than or equal to 1.0, which partial inertia ratio I.sub.X /I.sub.Y has the advantageous effect of retarding or arresting crack propagation in the structural member (10).

Abstract: A swashplate is provided for use in helicopters having a vertical main rotor axis. The swashplate includes a bearing, a first race member including a channel, a second race member including a channel, and a third race member including a channel. The channels of the first, second, and third race members cooperate to form a bearing-receiving slot. The bearing is positioned to lie in the bearing-receiving slot. The first and second race members are adjustably coupled to change the respective positions of their channels.

Abstract: A flexible beam rotor assembly for an aircraft includes a rotor spar having an axis of rotation and a hole through which the axis of rotation passes. A spindle has a teetering connection to the rotor spar, the teetering connection having a teetering axis above the rotor spar at the rotor axis of rotation. A spindle housing is nonrotatably mounted to the aircraft and rotatably receives the spindle. The spindle housing and spindle protrude through the hole in the rotor spar and are tiltable in response to pilot control on a left-right spindle pivot axis and a fore-aft spindle pivot axis. The left-right spindle pivot axis and the fore-aft spindle pivot axis are located below the teetering axis and above the rotor at the rotor axis of rotation. A pylon is pivotally mounted to the fuselage for fore and aft movement relative to the fuselage to absorb vibration due to rotation of the rotor during forward flight of the aircraft. The spindle housing is attached to the pylon by a universal joint.

Abstract: A cyclic and collective control system is provided for controlling rotor pitch in a rotary wing aircraft. The rotor blades are pivotally mounted on a hollow, spinning shaft. An angularly and vertically displaceable control shaft is mounted with the spinning shaft and carries a rotatable control hub at its end. The control hub is coupled through pitch link rods to the rotor blades. When the control shaft is displaced vertically within the spinning shaft, the rotor blade pitch is changed collectively. When the control shaft is displaced angularly relative to the spinning shaft, the rotational plane of the control hub becomes skewed relative to the rotor axis. This has the effect of changing the pitch of the rotor blades in accordance with their rotational position around the rotor axis and has the further effect of providing cyclic control.

Abstract: A hingeless rotor including a rotor mast driven in rotation about an axis of the rotor, a hub secured in terms of rotation to the mast, and at least two blades, each of which is, firstly, joined to the hub by a root attachment part comprising at least one arm which can twist about a longitudinal pitch-change axis of the blade and, secondly, equipped with a cuff which is rigid in torsion, surrounding the at least one twistable arm, and the radially external part of the cuff, with respect to the rotor axis is secured in terms of torsion to the blade and to the twistable arm about the pitch-change axis, while the radially internal part of the cuff surrounds, without contact, the at least one twistable arm and exhibits a pitch lever projecting towards the outside of the cuff and joined to a pitch-control rod, wherein, for each blade, an intermediate pitch-control ring which is rigid in terms of torsion about the corresponding pitch-change axis, and which surrounds the corresponding at least one twistable arm is a

Abstract: The installation links a supply conductor to an electrical device for de-icing a blade using at least one cable with a first stretch linked to the supply conductor by a connector and to a second stretch with an overhead hook in the form of flattened half loop, itself linked to the device for de-icing the blade by a second connector fitted on the blade, possibly via a straight and flat third stretch and a second overhead hook. The first hook is of nonscreened structure, with an elongate part of substantially flattened rectangular transverse section and with a concavity pointing towards a device for retaining and articulating the blade on a hub.

Abstract: The installation for removing electrostatic charge and passing lightning current between a conductor of each blade of the rotor and a metallic part of the hub comprises at least one conductive member integral with the member for linking the blade to the hub in its angular deflections, and in electrical continuity with the conductor of the blade and held elastically in permanent contact with a conductive terminal integral with the hub and in electrical continuity therewith.

Abstract: A composite cuff structure (40) for mounting the root end (14e) of a rotor blade assembly (14) to the radial arms (24a, 24b) of a rotor assembly yoke (24) and for accommodating a twist disparity therebetween. The composite cuff structure (40) is generally tubular in shape and is fabricated from a composite material having reinforcing fibers (70) disposed in a binding matrix. The composite cuff structure (40), furthermore, includes a blade-receiving sleeve portion (42), a yoke mounting portion (44), spanwise fold portions (46) and sidelobe portions (48), which portions (42, 44, 46, 48) are structurally integrated to form a unitary body. The blade-receiving sleeve portion (42) is disposed in combination with the root end (14e) of the rotor blade assembly (14) and includes first and second blade mounting segments (42a, 42b), which define a rotor blade attachment plane P.sub.B.

Abstract: A pitch control system for a vertically launchable and recoverable winged aircraft includes a collective and cyclic pitch control system, a drive yoke and a rotor hub. The collective and cyclic pitch control system is operably connected to two proprotor blades to cyclically control the pitch of each proprotor blade, so that the aircraft is capable of controlled helicopter mode flight when the aircraft body is pointed in a generally upward direction. Proprotor blade flapping caused by applying cyclic pitch control results in teetering of the rotor hub with respect to the drive yoke. Torsion bar springs are used with suitable mechanical linkages to resist this teetering motion and generate the hub moment which is transmitted to the airframe and used to maneuver the aircraft.

Abstract: This invention relates to a rotorcraft rotor head which includes an even number of blades arranged in groups of two blades (2) which are diametrically opposed to each other, and linked to each other by a connection system without any link with the rotor hub. Each blade (2) is articulated in flapping and in pitch on the hub body (1) by a sleeve (3) which is arranged between the root of the blade (2) and the hub body (1). The sleeve (3) bears against the periphery of the hub body (1) by a laminated spherical stop (5) and includes an introduction member for controlling the pitch of the blade (2). Each system for connecting two diametrically opposed blades (2) is comprised of two tie rods (4) which link the two diametrically opposed sleeves (3) of the blades (2). The two tie rods (4) are arranged parallel to the plane of the rotor on either side of the longitudinal axis which is common to the two diametrically opposed blades ( 2).

Abstract: A device for converting a rotational movement for directing displacement of a flowable medium is provided with a mount and two rotatably mounted fixed axles which are arranged at a distance from one another on the mount and on which are articulated two end portions of a half cube-linkage chain having two lateral members and a middle member, the two lateral members being connected to the fixed axles and to the middle member by means of pivot axles which are successively offset relative to one another by in each case 90.degree.. The device is characterized in that the middle member and at least one of the two lateral members of the half cube-linkage chain cooperate to form sheet-like driving elements for displacing flowable substances.

Abstract: A pitch adjustment assembly (100) for a bearingless rotor assembly (20) which includes a torque tube member (36) enveloping a flexbeam connector (22), which torque tube member (36) defines a geometric center (120) and is operative to impart pitch motion to the rotor blade assembly (20).

Abstract: A rotor blade subassembly for a rotor assembly having ducted, coaxial counter-rotating rotors includes a flexbeam, an integrated torque tube/spar member, and an aerodynamic fairing or rotor blade. The flexbeam is a laminated composite structure that reacts centrifugal loads and a majority of the bending loads of the rotor assembly. The flexbeam has a spanwise predetermined linear twist so that the pretwisted flexbeam is unstrained during specified forward flight conditions. The integrated torque tube/spar member is formed as a continuous, filament wound tubular composite structure having high torsional and bending stiffness that provides a continuous torsional load path and facilitates load coupling between the rotor blade and the pretwisted flexbeam. The spar segment of the functions as the primary structural member of the rotor blade subassembly and, is operative to react all bending, torsional, shear, and centrifugal dynamic loads of the rotor assembly.

Abstract: A snubber assembly for a rotor assembly having ducted, coaxial counter-rotating rotors that is design optimized to facilitate utilization of a self-aligning bearing and for installation inboard of the corresponding flexbeam-to-rotor hub attachment joint, thereby enhancing accessibility and reducing maintenance costs. The rotor hub of the rotor assembly is design optimized for securing the snubber assembly in combination therewith and includes a plurality of arms, each arm forming an outboard clevis for attaching the rotor assembly flexbeam to the rotor hub. Inboard of the clevis, each rotor hub arm includes an outboard internal bulkhead having a bolt hole therethrough and an inboard internal bulkhead having a bolt hole therethrough. The inboard and outboard internal bulkheads in combination define a bearing cavity and an internal cavity for securing the snubber assembly in combination with the rotor hub.

Abstract: The invention relates to an articulated rotor head for gyroplanes comprising a rigid central hub body (1), perpendicularly integrated with a drive shaft (2), each blade (3) being radially fixed to the hub body (1) by means of connecting and articulating components. These components each comprise:a spherical laminated elastomer stop (4) housed in the central hub body;a hollow sleeve (5) rigidly locked to the spherical laminated stop (4);an elastic return and drag damping brace (9) of the blade (3) arranged between the sleeve and the outer part of the rigid hub body (1) on a contiguous sleeve;a connecting and pitch articulation spindle (6) of the blade (3) connected to the foot of the blade (3) and a pitch lever (8) rigidly locked to the spindle (6) and which swivels about the pitch axis inside the sleeve (5) on two bearings, one of which at least forms a thrust stop (7) to transmit, from the spindle (6) in the sleeve (5), the thrust loads originating from the centrifugal forces on the blade (3).

Abstract: A flexbeam helicopter rotor having an improved connection between the flexbeam and the hub of the connecting pin variety but in which the high tensile fibers of the flexbeam do not wrap around the connecting pin, wherein the blade centrifugal loads and the blade lead-lag loads are reacted by the connecting pin at a station where it passes through drilled holes in the flexbeam inner end, and wherein the blade flapping motion imposed loads are reacted through two load paths in the flexbeam-to-hub connection, the first load path being created by a prying reaction between the flexbeam and the hub connecting flanges, and the second load path being created by the differential bending reaction between the flexbeam at the station of the drilled holes and the connecting bolts.

Abstract: A mid-beam jointed reconfigurable bearingless main rotor (BMR) assembly that includes reconfiguration joints that facilitate BMR assembly reconfiguration by main rotor blade removal or folding to reduce the structural envelope of a helicopter for rapid deployment, routine transport, and/or storage. The BMR assembly comprises a rotor hub structure that includes a plurality of radially extending flexbeams, combinations of torsion flexure members and main rotor blades disposed in combination with corresponding flexbeams, and torque tube subassemblies disposed in combination with corresponding flexbeams and torsion flexure member, main rotor blade combinations. Each reconfiguration joint is formed by a combination of an outboard joint segment of a flexbeam and an inboard joint segment of the corresponding torsion flexure member.

Abstract: Gyrocraft rotor head including a hub connected to each blade (2) of the rotor by a linking member which is integral with the blade (2) and which is linked to the hub body by a laminated spherical stop. Each blade (2) is fitted with an assembly (20) for elastic recall in drag with incorporated damping, one of whose extremities (22) is linked to the member linking the blade to the hub body. The linking member is constituted by an intermediate sleeve (11) comprising one part in the form of a ring (12) and one part fitted with at least one double clevis (14), the intermediate sleeve (11) being a single integral assembly of which the ring (12) surrounds the laminated spherical stop with which it is integrated and of which the double clevis or clevises interact with the structure for integration of the blade (2).

Abstract: A bearingless hub structure for a rotary-wing aircraft is provided, the structure including a hub body adapted to be securely connected to a rotor mast, a plurality of flexible beam members provided integrally with the hub body to extend radially outwardly, a pitch housing encircling each of the flexible beam members, and having a radially outward end portion which is rigid with a radially inward end portion of a rotor blade, a spherical bearing positioned adjacent to a radially inward end portion of the flexible beam member for supporting the pitch housing, a lead-lag damper positioned between the flexible beam member and the pitch housing, and the flexible beam members each having a flexible plate portion which is of a low bending rigidity in a flapping direction, a flexible portion provided radially outwardly of the flexible plate portion having a low bending rigidity in the lead-lag direction, and a twist-flex portion provided radially outwardly of the flexible portion.

Abstract: A helicopter blade having a connecting device made of composite synthetic material for connecting it to the hub of a rotor via a spherical joint comprising a rod housed inside a tubular portion of the connecting device; the rod being connected to the tubular portion by two diametrical through bolts offset along the rod, and the connecting device comprising, for each of the four holes engaged by the aforementioned bolts, a substantially axial strap of composite material looped about the respective hole.

Abstract: A main helicopter rotor has a number of blades and drive shaft that supports, at its top end, a hub defined by a rocking toroidal body, the inner and outer edges of which are connected to the drive shaft via respective spherical elastomeric joints having a common center on the axis of the drive shaft. The toroidal body is fitted with and supports a rigid tubular body substantially coaxial with the drive shaft. Each blade is connected to the hub by a connecting element extending through both the tubular body and the toroidal body and connected respectively to the same by a first and second elastomeric bearing.

Abstract: A main helicopter rotor has a number of blades, and a drift shaft supporting at its top end, a hub consisting of a rigid annular body integral and coaxial with the drive shaft. An elastically deformable torodial body surrounds and is connected to the annular body for defining, with the same, a closed-section torodial assembly. Each blade is connected to the hub by a connecting element extending at least partially through the annular body and the torodial body, and connected respectively to the same by a first and second spherical elastomeric bearing.

Abstract: A rotor for rotation about an axis includes a driving member rotationally fixed to a drive shaft and having a plurality of equi-spaced drive pins extending radially of the axis of rotation and in a plane of rotation perpendicular to the axis, and located in an elastomeric bearing assembly attached to a gimbal housing connected to a spherical elastomeric thrust bearing having a geometral center located at an intersection of the axis of rotation and the plane of rotation whereby in operation the rotor can be tilted in any direction about the center.

Abstract: A main helicopter rotor having a number of blades and wherein a drive shaft supports, at its top end, an annular hub integral with the drive shaft and in turn supporting, via a spherical elastomeric joint having its center on the axis of the drive shaft, and an elastic axial suspension, a toroidal body surrounding the drive shaft. Each blade is connected to the hub by a connecting element extending through both the hub and the toroidal body, and connected respectively to the same by a first and second spherical elastomeric bearing.

Abstract: A pitch change bearing assembly for a helicopter hub (10) having a yoke (14) and a grip (12) includes a shaft (24) having first and second ends (24a, 24b). A first radial elastomeric bearing (60) is disposed on the first end (24a) of the shaft (24). A second radial elastomeric bearing (62) is disposed on the second end (24b) of the shaft (24). The first and second radial elastomeric bearings (60, 62) are disposed parallel to one another. A third radial elastomeric bearing (66) is disposed on the shaft between and spaced apart from the first (60) and second (62) radial elastomeric bearings and is parallel to the first and second radial elastomeric bearings (60, 62). Structure (28, 30) is provided for attaching the third radial elastomeric bearing (66) to the grip (12). Structure (48, 50) is further provided for attaching the first and second radial elastomeric bearings (60, 62) to the yoke (14).

Abstract: An articulated helicopter rotor wherein the blade-to-hub connection consists of a spherical elastomeric bearing connected to the hub and a composite yoke connected thereto in series and consisting of a plurality of unidirectional high strength fibers bonded together to form a continuous strap which passes through a central opening in the elastomeric bearing and is pin-wrap connected to the hub at a single station and to the blade at two spaced stations produces a construction which is light in weight, easy to manufacture, ballistrically tolerant, redundant, and readily visually inspectable for structural integrity.

Abstract: A flexbeam 16 for a bearingless helicoptor rotor includes a composite beam 28, composed of unidirectional fibers bound in an epoxy matrix, having ribs 32, composed of unidirectional fibers bound in a urethane matrix, bonded to each horizontal face at the section of the beam 28 which accommodates lead-lag torsion.

Abstract: A flexbeam helicopter rotor having an improved snubber-vibration damper for positioning the flexbeam spar relative to the torque tube, wherein the snubber-damper is an elastomeric bearing having a spherical and a flat portion, and whose laminates are continuous, selectively preloaded and of selected material to provide increased fatigue life, size reduction, reduced laminate stress concentration, and reduced critical design stress in the snubber-vibration damper.

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: The system comprises a grip of composite material having belts, filament windings unidirectional material and fillers of off axis bias ply material for directing the CF exerted on the grip by the blade rotation to the clevis throat of the grip. The force is further directed through a CF fitting, a CF bearing and an OPCBA to the yoke, thereby maintaining the yoke in tension. Should this load path fail, the CF will be transmitted through the length of the grip to the IPCBA that will in turn load the yoke with the CF.

Abstract: A wind power plant construction includes a turbine with at least two blades, a shaft, and blade angle control apparatus. According to the wind power plant construction shown, supports are rigidly connected to the shaft substantially radially thereto, and are coordinated with the blades. At the extreme ends of the supports are flapping pivots, to which the blades are attached. The blade extends from the flapping pivot towards the shaft; that portion of the blade doing so constitutes an arm to which a control means is connected. The blade is weighted so that the centroid line and axis of rotation of the blade lie closer to the leading edge of the blade than does the buoyancy center.

Abstract: A pitch change bearing assembly for a helicopter hub (10) having a yoke (14) and a grip (12) includes a shaft (24) having first and second ends (24a, 24b). A first radial elastomeric bearing (60) is disposed on the first end (24a) of the shaft (24). A second radial elastomeric bearing (62) is disposed on the second end (24b) of the shaft (24). The first and second radial elastomeric bearings (60, 62) are disposed parallel to one another. A third radial elastomeric bearing (66) is disposed on the shaft between and spaced apart from the first (60) and second (62) radial elastomeric bearings and is parallel to the first and second radial elastomeric bearings (60, 62). Structure (28, 30) is provided for attaching the third radial elastomeric bearing (66) to the grip (12). Structure (48, 50) is further provided for attaching the first and second radial elastomeric bearings (60, 62) to the yoke (14).

Abstract: The invention relates to a rotor head having interblade ties with resilient return in lag and with built-in damping, wherein each tie is connected, to each of the two rotor blades joined by it, by articulation means comprising a main ball retained on a member connecting a blade to the hub and centered on or in immediate proximity to the pitch change axis of the corresponding blade.A single main ball may be connected to the adjacent ends of two neighboring ties by a connection member having the shape of a V open towards the hub, or else each tie is connected to a connection member by a respective one of two main balls offset transversely in relation to the pitch change axis of the blade and/or radially along said axis.Application to the main and/or auxiliary rotors of helicopters.

Abstract: A flexbeam for rotor blades of a helicopter comprises a flapping flexible structure forming a mast mounting and flapping part, a flexible structure forming a feathering and lead-lag motion part coupled with the flapping flexible structure, and a rotor blade mounting part located at the free end of the flexible structure and adapted to be coupled with a rotor blade. The feathering and lead-lag motion part comprises an elongated central member made of a composite fiber material, and a pair of elongated frame members disposed along the longitudinal sides of the central member. The frame members are each made of loops of unidirectional composite fiber material and has a Y-shaped cross section. The feathering and lead-lag motion part is fabricated by integrally joining the central member and the frame members along the longitudinal sides of the latter. The Y-shaped cross section has a pair of parallel ribs extending away from the central member.

Abstract: A spherical bearing for a helicopter rotor connects a rotor blade to a rotor hub. The bearing includes an outer race supported on the hub and an inner race spaced axially from the outer race supported by a shackle attached to the blade root. Each race defines a concentric spherical surface. Multiple laminates of elastomer and shims of metal are arranged alternately between the races. The laminates and shims are bonded to each other to form an assembly that is bonded to the races at radially opposite ends. Each laminate has an opening formed at its center extending through its thickness. A coupon of elastomer, whose damping characteristics exceed those of the laminates, is fitted within each opening with suitable dimensions to minimize control loads and flapwise damping, yet the coupon increases lead-lag damping.

Abstract: A helicopter tail rotor (10, 130) includes a drive mast (12) having an axis of rotation (14). A first blade pair (20) is mounted for rotation about the drive mast (12). The first blade pair (20) includes a pitch change axis (54) perpendicularly disposed to the drive mast axis of rotation (14). A second blade pair (34) is mounted for rotation about the drive mast (12) and is spaced apart from and parallel disposed to the first blade pair (20). The second blade pair (34) includes a pitch change axis (60) parallel to the pitch change axis (54) of the first blade pair (20).

Abstract: An auxiliary helicopter rotor on which at least two blades extend radially from a hub, each of which blades presents a root connecting it to the hub, and a beam having two wings extending respectively along the back and face of the blade; the wings of the beam diverging along the root in such a manner as to form a fork engaged both by a center plate on the hub, to which the fork is connected via a spherical joint, and by a flexible leaf extending from the center plate inside the fork and connected to the beam of the blade by means of an axial joint.