Abstract: The anti-vibration suspension device includes at least three diagonal bars each articulated on the transmission box and on the structure by a rigid lever supporting a damping weight itself articulated to at least pivot on this structure, and, for each diagonal bar, a tension bar also articulated on the transmission box and on the structure, the corresponding lever being articulated to the structure being articulated to at least pivot on the lower end part of the corresponding tension bar, which is flexible in tension.

Abstract: A propeller for aircraft has a tip-to-tip flex-beam spar and torsionally stiff hollow blades bonded to the spar throughout an outer portion of the blades. The spar has two end caps which are separated from each other at the hub and converge in the outer portion. The blades have an inner region which is not bonded to the spar, allowing an inner portion of the spar to twist during pitch changes. A counterweight is mounted to an arm extending from an inner end cuff of each blade. The counterweight is located out of the plane of rotation. The counterweight is also located on a side of a line opposite from the trailing edge, the line passing through the pivot axis perpendicular to the plane of rotation.

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: Rotor blade weighting apparatus comprising in combination at least one elongated rod carried within a rotor blade, and multiple weights received and retained on the rod, the number of weights adjustable for reducing vibration during rotor rotation.

Abstract: A rotor blade for a bearingless rotor of a helicopter includes a lift-generating airfoil blade, a flexbeam connecting the airfoil blade to a rotor head, and a control sleeve enclosing the flexbeam. The junction between the flexbeam and the airfoil blade is a separable junction (J) to allow the airfoil blade to be folded in a simple manner while maintaining a high lead-lag stiffness and reduced structural height of the junction (J). The junction (J) is formed by two connection arms (5.1, 5.2) arranged side-by-side in the lead-lag plane (E.sub.R) of the rotor blade (R). Preferably, the two connection arms extend from the inboard end of the airfoil blade (3) and receive the head (1.1) of the flexbeam (1) therebetween lying in the lead-lag plane (E.sub.R). A connecting fixture (6) connects the connection arms (5.1, 5.2) to the flexbeam head (1.1) using fasteners such as bolts (V.sub.1, V.sub.2) that are spaced laterally from each other at a spacing distance of at least 1.

Abstract: The rotor comprises, for each blade, an inner and an outer flap stop which are fixed to the blade and have a bearing surface which is planar with a cylindrical portion, facing an inner and an outer flap stop fixed to the hub and with torus-shaped bearing surfaces with their convexness facing towards the flap stops of the blade and in the shape of an arc of a circle centered on the axis of drag of the blade.

Abstract: Each blade of the rotor has a rigid root oversleeve connected to a torsionable and flexible root strip by two laminated, spherical support half bearings, fixed by their outer frame with double rigid horns the lateral ends of which facing each other on each side of the strip and half bearings are clamped towards each other and against struts so as to allow a significant, calibrated pre-compression of the half bearings. The double horns and/or struts are fixed axially to the oversleeves by fixing elements distinct from the compression means of the double horns on the struts and perpendicular to these compression horns on the struts and perpendicular to these compression elements. One of the struts, possibly in a single piece with one double horn, is also in a single piece with a pitch lever.

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: In a helicopter having three or more rotor blades, and with mechanical actuation of the rotor blades by a swash plate and a superimposed electrohydraulic active control system, in addition to three regulating units (18) is an actuator (4) between a rotatable part (9) of the swash plate and a rotorblade mount (2) of each rotor blade. This arrangement allows for the safe actuation of individual blades in helicopter noise reduction, and increased efficiency at a modest constructional effort.

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 fluid and elastomer damper includes a first and second members and an elastomer section flexibly mounting the second member to the first member and allowing lateral movement therebetween. The elastomer section includes an inner wall forming a portion of a cavity defined within the damper and a damping fluid disposed within the cavity. A flexible damping plate separates the cavity into first and second chambers. At least one passageway is formed between the damping plate and the inner wall, the passageway exhibiting a gap dimension between the wall and the damping plate. When lateral movement occurs between the first and second members, the gap dimension is maintained substantially constant by flexing of the damping plate along the lateral direction.

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: This process consists in making separately a set of individual plies consisting of rods impregnated with thermoplastic resin, in assembling several individual plies in order to form a rod bundle, in encasing at least the rods in at least one elastomer and in curing the injected elastomer. The ends of the rods have a rectangular shape, the rods having central parts joined to the ends by transition zones such that the surface area of the cross-section of the rods is constant and the length of the transition zone is very small. Cut pieces consisting of fibers, arranged on each side of the ends of the rods comprise fibers oriented at more or less 45 degrees to the longitudinal fibers of the rods.

Abstract: The locking device comprises, for each blade, at least one first subassembly with a fork for locking a finger, one of the fork and finger pivoting on a chassis attached laterally to the hub between the linking members of two neighboring blades, the other element being fixed to the linking member and projecting laterally towards the other linking member so that the pivoting element can be moved between a position in which it is engaged over the finger for locking the blade at least in terms of pitch, and a disengaged position for unlocking.

Abstract: A helicopter rotor has two or more blades which extend from a hub and has an adjustment mechanism for adjusting the lead/lag variation of the blades which typically occur due to manufacturing tolerance variations or to changes which occur through operation such as softening of the supporting elastomer dampers. One embodiment of the invention incorporates an end plate on an upper damper with a lug positioned adjacent to a lug on the torque tube such that the end plate of the damper can be changed relative to the longitudinal axis of the blade. For example, a .+-.1/2 degree adjustment can be made in the blade angle relative to the hub to insure that lead/lag errors are reduced. In another embodiment, the damper set includes extended metal shims adjacent to the end most laminate plys of the upper and lower dampers such that these shims can be bolted to the end plates of the snubber assemblies for step increasing the stiffness of the assemblies.

Abstract: A main rotor is provided for use on a model helicopter. The main rotor includes rotor blades having an inboard section and an outboard section. The inboard section includes a higher camber, thin, wide airfoils, and greater pitch and camber relative to the outboard section. The outboard section includes an average chord length that is less than the chord length of the inboard section, The rotor blades also include a blade body that is semiflexible to bend during a crash landing of the model helicopter.

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: The present invention relates to an improved helicopter rotor system including a contoured flexure strap having a simplified geometrical configuration. The flexure strap serves to join the rotary hub assembly with the rotor blades and is formed of fiberglass. The primary load carrying fibers of the flexure strap preferably extend in the same direction as the spanwise axis of the flexure strap in order to withstand the centrifugal forces acting on the strap. The inboard end portion of the flexure strap includes two separate ends, with one of the ends extending in a vertically upward direction and the other end in a vertically downward direction. This allows the ends of flexure straps positioned on opposite sides of the rotary hub assembly to overlap one another and be retained in place by a single pin and bolt assembly.

Abstract: A composite rotating swashplate for a helicopter rotor system which includes rotor blades with associated control rods. The control rods control the pitch of the rotor blades. The composite rotating swashplate according to the present invention includes an outer tubular ring with an inner tubular ring located within the outer ring. The outer ring is made from braids of tri-axial graphite fibers interwoven with unidirectional plies. The inner tubular ring is made from braided .+-.45 degree graphite fibers. A support ring is located within the outer ring and external to an inboard periphery of the inner tubular ring. A plurality of apertures are formed through the outer and inner rings. The apertures are adapted to receive the terminal ends of the control rods. Mounting bolts extend through at least one wall of the outer and inner rings and attach the terminal ends of the control rods to the swashplate.

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: An optimized composite flexbeam (10) having a plurality of adjoining regions including a hub attachment region (HAR), a blade attachment region (BAR), a pitch region (PR), an outboard transition region (OTR) disposed between and adjoining the pitch region and blade attachment regions (PR, BAR), and an inboard transition region (ITR) disposed between and adjoining the pitch and hub attachment regions (PR, HAR). The inboard transition region (ITR) includes a first transition subregion (ITR-1) and a second transition subregion (ITR-2) wherein the second transition subregion (ITR-2) defines a width conic and a critical width transition subregion (CR.sub.wt). Furthermore, the first and second inboard transition regions (ITR-1, ITR-2) are composed of a combination of unidirectional and off-axis composite materials (U, O) wherein the off-axis composite material (O) defines a percentage %O of off-axis composite material (O) and wherein the percentage %O in the critical transition subregion (CR.sub.

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: An optimized composite flexbeam (10) having a pitch region (PR) which includes a core laminate (50) of unidirectional fiberglass material (U.sub.F), and face laminates (52) of unidirectional graphite material (U.sub.G) bonded to mating surfaces (50.sub.M) defined by the core laminate (50). The core laminate (50) and face laminates define an aspect ratio which is greater than or equal to 10 and define chamfered edge surfaces (54.sub.S). Each chamfered edge surface (54.sub.S) defines a critical acute angle .alpha. with respect to the flapwise bending neutral axis (X.sub.A) of the pitch region (PR) and defines a lateral edge (54.sub.E) disposed a vertical distance X from the flapwise bending neutral axis (X.sub.A). The critical acute angle .alpha. is between about 14 degrees to about 22 degrees and the vertical distance X is about 12.5% to about 37.5% of the pitch region thickness dimension (T.sub.PR).

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 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: An axisymmetric elastomeric bearing assembly (30) for an articulated rotor hub assembly (10), which axisymmetric elastomeric bearing assembly (30) is disposed in combination with a rotor assembly yoke (24) and hub retention member (12) of the rotor hub assembly (10) and is operative for accommodating the multi-directional displacement of a rotor blade assembly (14) thereof. The axisymmetric elastomeric bearing assembly (30) includes a central bearing element (32) having a spherical bearing surface (32s) defining a bearing focal point (30f) and spherical elastomeric elements (34) bonded to the spherical bearing surface (32s) on opposing sides of the bearing focal point (30f). Each of the spherical elastomeric elements (34) have a plurality of alternating layers of elastomer and nonresilient shims (36, 38) which have a center of curvature which is coincident with the bearing focal point (30f) and disposed at increasing radii therefrom.

Abstract: For each blade, the cuff which is rigid in torsion, surrounding the corresponding rotor attachment twistable arm, bears two opposed pitch levers each articulated to one respectively of two intermediate connecting rods which are moreover articulated to one and the same transmission lever on either side of a pivoting link by means of which this lever pivots on a pivot secured to the rotor mast. The transmission lever is additionally articulated to the pitch-control rod at a point which is offset with respect to its pivoting link. A crossmember is articulated to the connecting rods and interacts with an assembly having a drag damper, this assembly itself being articulated to a fixed point secured in terms of rotation to the rotor mast.

Abstract: A mounting assembly (50) for mechanically interconnecting a helicopter rotor blade (12) to a rotor hub assembly (10) and for mechanically interconnecting the rotor blade (12) to a damper assembly (52) and a pitch control input assembly (54). The rotor hub assembly (10) includes a hub plate (16) having a hub plate aperture (22) for mounting a rotor assembly yoke (24). The rotor assembly yoke (24) includes upper and lower radially extending arms (28a, 28b) which are disposed above and below the hub plate (16) and which include a set of mounting apertures (29) formed through the proximal end thereof. The mounting assembly (50) includes upper and lower clevis arms (60a, 60b) formed at the root end (56) of the rotor blade (12), a horn/damper fitting (64) interposed between the upper and lower clevis arms (60a, 60b), and upper and lower spacer plates (90a, 90b) disposed between the clevis arms (60a, 60b) and the radially extending arms (28a, 28b) of the rotor assembly yoke (24).

Abstract: In the rotor, the pitch lever of each blade is connected to the tab of the pitch control spider by a ball joint mounted on a wrist pin and received with clearance in an oblong opening in a ring. The axially offset bearing surfaces of the cuff of the blade are mounted with a radial clearance in the bearings of the hub on which they swivel about the pitch axis of the blade. These radial clearances enable contacts of the ball joint against the edge of the opening on the side of the ends of its minor axis, but prevent these contacts on the side of the ends of the major axis of the oblong opening.

Abstract: A mounting assembly (100) is provided for securing a helicopter snubber bearing (70) to a bearingless rotor assembly (10) which includes a flexbeam connector (22) mounted to a torque drive hub member (18). The mounting assembly (100) includes a retainer fixture (102) for mounting a retainer (104) which engages an inner bearing race portion (88) of the snubber bearing (70). The retainer fixture (102) is mounted to the flexbeam connector (22) and includes an inboard end portion (112), a restraint portion (114) extending radially outboard thereof, and a seat portion (116) disposed therebetween. The retainer (104) is disposed in register with, and is compliantly bonded to, the seat portion (116) of the retainer fixture (102), and furthermore abuts the restraint portion (114) which provides redundant retention therefor.

Abstract: The invention relates to an antivibration device comprising two rigid strength members that are parallel and perpendicular to a first axis Z, and at least one laminated element interposed between the two strength members, said laminated element being made up of alternating layers of a rigid material and of elastomer which are disposed perpendicularly to the first axis, said laminated element enabling the two strength members to move relative to each other along a second axis Y that is perpendicular to the first axis. According to the invention, the device further includes a hydraulic damper which presents at least two leakproof cavities that are deformable and that are interconnected by means of a narrow channel, the two leakproof cavities and the narrow channel being filled with a liquid, each leakproof cavity being defined, at least in part, by a deformable wall which is fixed to both of the strength members and which permits them to move relative to each other parallel to the second axis.

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: The blade has its lower-surface and upper-surface skins of its shell, its front and rear filling bodies and its spar made of a composite material having the same thermoplastic matrix, preferably made of PEEK, reinforced preferably with carbon fibres. The spar is extended outside the shell by an integrated rooting part with linkage attachment, in a loop or laminate, in the same thermoplastic composite. The method consists in assembling, by melting, under pressure, all the thermoplastic composite components of the blade, in a single step after manufacturing these components in the form of prefabricated elementary pieces.

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: The blade has its lower-surface and upper-surface skins of its shell, its front and rear filling bodies and its spar made of a composite material having the same thermoplastic matrix, preferably made of PEEK, reinforced preferably with carbon fibres. The spar is extended outside the shell by an integrated rooting part with linkage attachment, in a loop or laminate, in the same thermoplastic composite. The method consists in assembling the spar with the skins, after manufacturing these components in the form of prefabricated elementary pieces, by injecting under pressure a fluidized thermoplastic composite with short reinforcing fibres moulding the filling bodies.

Abstract: A hybrid composite flexbeam for a soft inplane bearingless main rotor assembly has eight spanwise regions: a hub attachment region; a first tapered region; a second tapered region; an inboard transition region; a pitch region having a cruciform configuration; an outboard transition region; a tapered outboard transition region; and a main rotor blade, torque tube attachment region. The pitch region is formed from unidirectional fiberglass plies, a 50/50 admixture of unidirectional fiberglass and graphite plies, and unidirectional graphite plies, all of which extend from root to tip of the hybrid flexbeam. Unidirectional fiberglass and graphite plies of varying lengths are interleaved in the second inboard tapered region. Fiberglass and graphite cross plies of varying lengths are interleaved in the first inboard tapered region. Fiberglass and graphite cross plies and unidirectional fiberglass plies of varying length are interleaved in the outboard tapered region.

Abstract: A rotor head for a rotary wing aircraft having a plurality of rotor blades, such that each blade is coupled to the hub by an attachment assembly. The attachment assembly includes a thrust bearing device attached to the hub for allowing angular oscillations, and drag damping device coupled between the blade and the hub for damping movements of drag caused by rotation of the rotor head. The drag damping device has visco-elastic elements which are pivotable with respect to each other about a common axis. The damping device is also disposed to pivot in a flapping direction of the blade through a pivot joint.

Abstract: A device for linking a blade to the hub comprising a laminate attachment at the end of the rooting part with torsion bars of the blade, the laminate attachment being in abutment against the pins for holding on the hub. The opposite blades of the rotor may be arranged angularly offset with respect to the other blades.

Abstract: A flexbeam for a soft inplane bearingless main rotor assembly has six spanwise regions: a hub attachment region; a first tapered region; a second tapered region; a pitch region; a tapered outboard transition region; and a main rotor blade, torque tube attachment region. One described embodiment of the flexbeam is fabricated from continuous unidirectional fiberglass plies having a 0.degree. fiber orientation, unidirectional fiberglass plies of varying lengths having a 0.degree. fiber orientation, and graphite cross plies having .+-.45.degree. fiber orientations. The pitch region is formed solely by the continuous fiberglass plies which define a rectangular cross section therefor. The second tapered region is formed solely by the continuous fiberglass plies and the fiberglass plies of varying lengths. The ends of the fiberglass plies terminate in a distributed arrangement in the second tapered region to define the taper thereof.

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: 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 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 a cylindrical elastomeric bearing with wide angular deflection comprising three cylindrical elements: a central element (1) and two lateral elements (2, 3) arranged either side of the central element (1). Each torsible cylindrical element is made up of a deformable elastomeric central part, relatively flexible angularly and relatively rigid radially, which is rigidly locked to an inner armature and to an outer armature; the outer armature (6) of the central element (1) and the inner armature (8, 11) of each lateral element (2, 3) are rigidly locked together so as to form a single part, the common armature (13).

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 heavy duty elastomeric bearing typically of annular shape comprises a pair of rigid end members spaced apart and interconnected by an element of elastomeric material having embedded therein a plurality of substantially rigid reinforcing interleaves each arranged to lie in respective planes generally parallel with confronting surfaces of the rigid members. One or more of the reinforcing interleaves lying substantially mid-way between the confronting surfaces of the end members has a greater thickness than one or more of the interleaves which lies closest to at least one of the end members. The confronting surfaces, elastomeric layers and reinforcing interleaves may each be of annular part-spherical shape.