Abstract: The torsible, flexible linking arm with integrated flexion damping according to the invention includes, between two rigid end portions, a flexible central portion constituted by a peripheral bundle (6) of rods (8) of fibres with high mechanical strength encapsulated in a flexible, vulcanized elastomer (9), and by a central damping core (7) with a strip (13) shearing a damping gel (12) filling a tight, flexible bladder (11) embedded in the elastomer (9). When deformations occur in the plane of the strip (13), the latter shears the gel (12), which produces damping that is added to that resulting from the deformation remanence of the elastomer (9). Application to the linking of two rigid bodies such as a rotor blade and its hub.

Abstract: The invention relates to a combined bearing device for a rotorcraft rotor or a rotor equipped with such a bearing device. In the rotor, each blade is held on the hub by a flexible arm surrounded without contact by a rigid stub sleeve by a combined bearing device including a cylindrical plain angle of attach bearing, a spherical ball joint with visco-elastic element for resiliently returning the blade under flapping and drag conditions, and with an integrated damper for damping the angular oscillations of the blade under drag conditions, of the hydraulic rotation damper type with vanes for laminating the hydraulic fluid and compensation chambers for the expansion of this latter, the hydraulic damper being integrated in the spherical thrust bearing and its compensation chambers belonging to a hydraulic automatic play take-up device for the plain bearing.

Abstract: An improved helicopter rotor flexbeam (20) comprises a pair of generally parallel outwardly open, cross-sectionally C-shaped beams (25) of a geometry which defines therein a first inboard region (A) of enhanced out-of-plane flexibility and a second outboard region (B) of enhanced in-plane and torsional flexibility.

Abstract: In order to avoid a negative coupling between blade lead-lag movements and lade angle adjustment movements in a helicopter rotor, the angle (.beta.) between a control rod (5) for the blade angle adjustment and an effective damping plane (M) of the rotor is increased as compared to the respective angle in conventional rotors. This increase of the angle (.beta.) is accomplished by arranging a damping device (9) having the effective plane (M) for suppressing blade lead-lag movements in such a way on a blade angle control sleeve (4), that the effective plane (M) of the damping device (9) encloses an angle (.alpha.) with the lead-lag plane of the rotor.

Abstract: A two-bladed aircraft rotor is disclosed having blades mounted for freedom of blade motions, at least in the flapping sense and in the pitch-change sense, with the blades driven by flexible bellows.

Abstract: The invention provides an integrated hub-mast with a single piece tubular body which supports, by its hub body part (3), a reinforcing girdle (6) on each side of which openings (10, 11) are formed. For each blade of the rotor a retaining and pivoting member (13), formed preferably by a spherical stratified stop, is fixed to the girdle (6) and is retained in the hub body (3), and this member (13) is also fixed between the ends inside the hub body (3), of the lower (20) and upper (21) branches of a forked fastening part (19) connecting the blade to this member (13), these branches passing through the openings (10, 11) of a corresponding pair of openings. A heel (23) fixed under the lower branch (20) bears against a reciprocal ring (24) mounted on a support (29) in the hub-mast (1), which has external fastenings for coupling to resilient return and drag damping members of the blades.

Abstract: The lag-torsion flexure portion (16) of a flexbeam (10) having segregated lag-torsion flexure portions (16) and flap flexure portions has multiple longitudinal lobes (98A-98G, 100A-100G) formed by multiple grooves (90A-90F, 92A-92F) extending from the upper (94) and lower (96) surfaces of the lag-torsion flexure portion to a central planar portion (102) thereof. The bases of the grooves are radiused (r) for favorable stress distribution while allowing for torsional and lead/lag softness in the lag-torsion flexure portion. The preferred number of grooves is an even number, such as six, resulting in an odd number of lobes. The lobes may decrease in height from the central lobe to the edgemost lobes (FIG. 12A). The lobes may be radiused at the upper and lower surfaces of the lag-torsion flexure portions (FIG. 12B). The lobes may be formed of alternate layers of unidirectional longitudinal fiber (32) extending the length of the flexbeam and elastomeric material (112) (FIG. 12D).

Abstract: A helicopter rotor includes a plurality of rotor blades attached to a rotor hub by flexure members adapted during operation to permit pitch changes and flap and lag movements of the rotor blades. Each flexure member comprises a plurality of longitudinally extending reinforcing plates which in cross section extend generally radially from a geometric center of the flexure member and are enclosed in a resilient matrix material.

Abstract: A bladed aircraft rotor is disclosed having blades mounted by means of flexible devices providing freedom for blade motions, at least in the flapping sense and in the pitch-change sense, without employment of flapping or pitch bearings or pivots, the rotor also being provided with a central bearingless joint for transmitting thrust forces while providing freedom for angular movement of the rotor as a whole about a center point on the axis of rotation. A constant velocity torque-transmitting system is also provided.

Abstract: A rotor for a rotary wing aircraft has two damping structures on the outs of the blade angle adjustment sleeve. Each damping structure is a sandwich of an elastomeric layer between two stiff cover layers. A two-armed strut passes through the blade neck and is connected at its center in a pivoting manner to the blade root. The threaded outer ends of the two-armed struts pass through the respective sandwich for yieldingly connecting the radially inner end of the blade angle adjustment sleeve to the blade root. By tightening nuts on the threaded strut arms the elastomeric layer may be compressed. Thus, the damping structure performs, in addition to the damping function, a connecting function for the blade angle adjustment sleeve.

Abstract: A rotor, especially for rotary wing aircraft, has a rotor hub (1) with one r more torsionally stiff rotor hub arms (1.1) projecting radially outwardly. A rotor blade (2) having a blade root (2.1), a blade wing section (2.3), and a torsionally flexible blade neck (2.2) is attached by bolts (3) to each rotor hub arm (1.1). A torsionally rigid blade angle control sleeve (5) extends without contact along each blade neck (2.2) and is rigidly connected at its radially outer end to the blade wing section (2.3) and is movably connected at the radially inner end to the blade root (2.1). In order to isolate the blade control from any blade flapping movements, and to reduce the distance between the flapping hinge point and the rotor hub (1), the rotor hub arm (1.1) is flat in a direction perpendicular to the blade rotation plane and is more flexible to blade flapping movements than the blade neck (2.2) is. The blade root (2.1) is in the form of a yoke or fork for attachment to the rotor hub arm (1.

Abstract: A low vibration helicopter rotor including a four-bar linkage arrangement which permits the straight line connecting the center of gravity of each pair of diametrically opposed rotor blades to intersect the rotor hub geometrical center at all cyclic conditions.

Abstract: A bearingless hub structure for rotary-wing aircrafts comprising a hub body ecured to a rotor shaft, a plurality of radially extending flexbeams integrally formed with the hub body, and pitch housings enclosing each of the flexbeams in spaced relationship, the pitch housing having a radially outer end portion rigidly secured to an inboard end of a rotor blade and a radially inner end portion supported by a spherical bearing in the vicinity of a root end of said flexbeam.The flexbeam consists of a flexible element of low lead-lag stiffness and a torsion element of low torsional stiffness located radially outside the flexible element. The flexible element consists of two beam-like members having radially inner ends spaced in the lead-lag direction and extending radially outward with narrowing the distance between them, the beam-like member having radially outer end connected to a radially inner end of the torsion element.

Abstract: A flexurally, axially and transversely stiff link for providing a connection of low torsional stiffness between structural elements. The link includes an elongate flexurally stiff tapered beam extending longitudinally inside a filament-wound composite tube of low torsional stiffness and an elastomeric bearing interposed between the small end of the beam and the tube. An inboard connector assembly connects the beam and tube to one of the structural elements, and an outboard connector assembly connects the tube to the other structural element. Tensile loads are carried by the tube; however, when torque is applied, the elastomeric material permits the tube to twist relative to the beam while enabling shear loads to be transferred therebetween. Modified embodiments of links having enhanced flexural and tensile load carrying capabilities are disclosed.

Abstract: The invention relates to a device incorporating retractable stops for limiting the flappings of the blades of the main rotor of a rotorcraft. Each lower stop comprises a convex roller presenting a convex stop surface and bearing a weight at the end of an arm. By its convex roller, the lower stop is mounted to pivot about the pin for retaining the blade on the hub. On the ground, the bearing member is in contact with a lower bearing surface fast with the blade at the level of the pitch control lever, in order to limit the downward flappings of the blade. The lower stop pivots about the pin above the lower plate. The upward flappings of the blade may be limited by upper stops disposed substantially symmetrically below the upper plate. A second lower weight, returned by a spring, and engaging by a nose-shaped element in a notch in the rear of the bearing surface, acts as upper stop. The invention is more particularly applicable to equipping helicopters.

Abstract: An improved flexure member in a helicopter rotary system is devised wherein the flexure member is made of wound monofilamentary resin impregnated material comprising a fiber matrix and is formed in a flat strap disposed through a rotary hub of the rotor system and integrally extends from the flat strap to form a transition member and then to a cruciform flexure member having an X-shaped cross section. The cruciform member then extends and attaches to an outboard fitting adapted for coupling to the root of a rotor blade. In one embodiment the fiber matrix is wound around cylindrical lugs which forms the outboard fitting in combination with the integral extension of the cruciform member. The cruciform member is particularly characterized by including a woven X-shaped reinforcing fabric disposed within the X-shaped member about which fabric the monofilamentary layers are formed thereby forming each leg of the X-shaped cruciform.

Abstract: A high speed, downwind horizontal axis wind turbine includes three circumferentially spaced lightweight blades having inner support arms and radially outwardly disposed airfoil configured blade segments which are pivotally connected to the support arms, so as to fold straight downwind under high wind conditions or high rotating speeds. A spring biased control mechanism serves to rotate the airfoil segment of each blade about its longitudinal axis as the blade is folded downwind, so that a simultaneous folding and feathering action is obtained to prevent damage to the turbine in high wind conditions or under high rotating speeds.

Abstract: A helicopter rotor system in which a plurality of rotor blades are attached to the rotor mast. Each blade has a spar formed of fibers bundled and bonded together inside a skin. These fibers are divided into two bundles, each of which has a bight with a bend and two arms that double back into the spar. The bights are joined to the mast by spaced-apart attachments. The attachments may be plate-like, and can be shaped to provide initial coning and camber angles.

Abstract: A structural element which is particularly suited for use in accommodating torsional displacement while carrying various axial, transverse, and flexural loads. The structural element is of a multi-component construction which includes at least one elongated tube-like thin wall member having a pair of longitudinally-extending edges. The wall member is laterally engaged and constrained by one or more stabilizers which permit yielding relative motion between the edges when torque is applied.

Abstract: A rotor blade, for example for a rotary wing aircraft, has a wing section d a root section interconnected by a neck section surrounded by a blade angle adjustment sleeve which is stiff against torque moments for transmitting blade angle adjustment movements through the sleeve to the wing section. The trailing edge of the sleeve is provided with a gap which extends, at least partially, alongside the rear edge of the neck section for visually inspecting the neck section inside the sleeve even when the root section is connected to a rotor hub. A reflecting mirror may be used for inspecting all sides of the neck section through the gap.

Abstract: Helicopter rotor on which a number of blades are each connected to a perimetrical bridge element on a hub by means of a fork element extending round the said bridge element and connected to it by means of two elastomer supports, arranged in series, of which one is designed to dampen at least operation of the blade in the hub plane.

Abstract: A composite helicopter hub yoke is described. The yoke is made up of glass fibers unidirectionally oriented in the direction of principle stress, i.e. along the length of the yoke. The yoke also has clevis sections on either end and the clevis sections additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the unidirectionally oriented continuous glass fibers to produce crack resistance, damage tolerance, and integrity inspectability.

Abstract: A composite torque tube for a helicopter rotor hub is described. The torque tube contains upper and lower load bearing surfaces connected by two sidewall portions. Both the sidewall and load bearing portions contain filament wound glass fiber reinforced epoxy resin such fibers having a .+-.45.degree. orientation. The upper and lower load bearing portions additionally contain a plurality of multiaxially oriented plies of continuous unidirectionally oriented graphite fibers interleaved with the glass fibers so as to produce a torque tube with crack resistance, damage tolerance, light weight, strength and integrity inspectability.

Abstract: A composite helicopter rotor hub is described having a composite retention plate, yokes and torque tubes. The retention plate is made up of graphite and glass fiber reinforced epoxy resin. The graphite fiber reinforcement is in-plane isotropically laid continuous graphite fibers and the glass fiber reinforcement comprises segments of fiberglass continuously and circumferentially wound around the areas of retention. The yoke is made up of glass fibers unidirectionally oriented in the direction of principle stress, i.e., along the length of the yoke. The yoke also has clevis sections on either end and the clevis sections additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the unidirectionally oriented continuous glass fibers. The torque tube contains upper and lower load bearing surfaces connected by two sidewall portions.

Abstract: A low drag, bearingless coupling is provided between a blade and hub of a helicopter rotor system by coupling the hub and blade together by means of a planar, elastic flexure or element which extends between the blade and the hub in a generally azimuthal direction in the rotor plane. The thickness of the flexure is such so that it is smaller than the adjacent blade or hub thicknesses so that the aerodynamic cross section presented by the flexure to air flow is negligible. The flexure is particularly characterized by having a bend in the coupling between the hub and blade. In the illustrated embodiment the flexure is integral and "W"-shaped with a "U"-shaped segment of the "W"-shaped flexure extending between each side of the adjacent blade and hub arms. The flexure may be made of rod having a circular cross section or of flat plate formed in a shape to have the desired elastic and resilient characteristics.

Abstract: Apparatus for supporting the rotor blades of a helicopter is disclosed. Support in droop under both statically and dynamically loaded conditions is discussed. The droop stop mechanism 34 has low susceptibility to the deleterious effects of snow/ice or dirt contamination. The droop stop seat 42 is mounted for rotation in a corresponding receptacle 50 at the base of the rotor blade assembly 14 and is slidable between static stop and dynamic stop positions along the pitch axis of the blade to be supported.

Abstract: Helicopter rotor on which the blades are each connected to a center hub plate by means of a U-shaped fork connected to the hub by an elastomer support, the latter supporting a static supporting device for limiting dynamic oscillation on the relative blade in the vertical plane, the said device providing for use of a pin faceted on the side, mounted so as to turn on a taper seat integral with the relative fork and designed to engage with a mating surface integral with the hub.

Abstract: A bearingless helicopter rotor includes an integral damper and pitch change assembly (16) adapted to damp lead/lag movements of a rotor blade and to change the pitch of the rotor blade. In described embodiments, the assembly includes a generally tubular body portion (17, 27) closed at one end and attached by torque transmitting means (18, 28) to a flexure member blade attachment and a rod (20, 29) protruding axially from the other end of the body portion and attached adjacent the rotor hub. Pitch change movements are effected by rotation of the body portion about its longitudinal axis and damping of lead/lag movements either by metering of an incompressible medium across a piston (23) in a chamber (24) formed internally of the body portion or by an annular body of elastomer material (34) bonded to the outside diameter of the rod and the inside diameter of the body portion.

Abstract: A flexible blade neck of a helicopter rotor blade is bridged by a torsion gid sleeve for the blade angle adjustments. The radially outer end of the blade neck and sleeve are rigidly connected to the wing section of the blade. The radially inner end of the blade neck forms a blade root which is secure to the rotor head or hub. Additionally, the radially inner ends of the blade root and of the sleeve are interconnected by a ball and socket arrangement permitting a universal movement between the sleeve and the blade neck, thereby decoupling sleeve movements from the blade neck and vice versa.

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 low drag, bearingless coupling is provided between a blade and hub of a helicopter rotor system by coupling the hub and blade together by means of a planar, elastic flexure or element which extends between the blade and the hub in a generally azimuthal direction in the rotor plane. The thickness of the flexure is such so that it is smaller than the adjacent blade or hub thicknesses so that the aerodynamic cross section presented by the flexure to air flow is negligible. The flexure is particularly characterized by having a bend in the coupling between the hub and blade. In the illustrated embodiment the flexure is integral and "W"-shaped with a "U"-shaped segment of the "W"-shaped flexure extending between each side of the adjacent blade and hub arms. The flexure may be made of rod having a circular cross section or of flat plate formed in a shape to have the desired elastic and resilient characteristics.

Abstract: A structural element capable of resilient twisting about an axis including a plurality of axially extending open section members of decreasing transverse dimension nested together with adjacent ends of the members being rigidly interconnected at each end of the element.

Abstract: A helicopter rotor hub having a lobed shape defining a plurality of bridge structures each allowing the attachment of a respective blade; each bridge structure is formed of superimposed sections of three annular bands, of synthetic material, the intermediate one of which forms an outer frame extending around the whole of the periphery of the hub, while the other two define one of the said lobes and connect the said outer frame to an inner metal structure.

Abstract: FH (FLEX-HUB) helicopter rotor on which each blade is connected to a center hub by a fork having two arms on one side for connection to the relative blade and integral, on the other, to a rod connected to the hub by an elastomer support; the forks being interconnected by a polygonal ring passing between the said arms on each fork and each side of the said ring being supported centrally by a flexible arm extending radially from the hub.

Abstract: The invention concerns a helicopter rotor, the rigid hub (1) of which comprises a central drum (2) which is disposed substantially in line with the rotor mast (3) and which carries an upper plate (4) and a lower plate (6). This rigid hub (1) is connected to the root of each blade (26) by way of a laminated spherical stop (13) and a resilient-return drag brace. Each blade (26) comprises, in the zone of its root, a rigid loop (27) which surrounds the laminated spherical stop (13) in a continuous manner and is engaged in the inner movable fitting (24) of this stop (13) by means of a wedge (30) co-operating with the outer fixed fitting (15) of the stop (13).

Abstract: Diametrically opposed rotor blades of a helicopter rotor are interconnected by a strap member which is flexible in torsion and in a plane perpendicular to a plane of rotation and has a plan profile extending between leading and trailing edges. Each rotor blade is provided with inwardly extending lever means adapted for attachment to drive means externally of the strap plan profile and adjacent one of its edges and to pitch control means externally of the plan profile and adjacent the other of its edges. In one embodiment, the lever means comprise individual levers formed integral with a connecting member rotationally fixed to the rotor blade and in a further embodiment the lever means comprise an inwardly extending torque sleeve. The drive means attachments of opposed blades lie along a common axis parallel to the plane of rotation and intersecting the axis of rotation at approximately 45 degrees to a longitudinal axis of the strap member.

Abstract: The blades or wings of a rotor for example of a rotary wing aircraft, are nnected to the rotor head in a hingeless and bearingless manner by a blade neck section, which is flexible relative to torsion loads, flapping movements and lead-lag movements. The blade angle adjustments are made by a torsion stiff control rod bridging the flexible blade neck section. The control rod is flexible relative to flapping and lead-lag movements. The radially outer end of the control rod is rigidly connected to the respective wing. The radially inner end of the control rod is connected to the rotor head in such a manner that the control rod is movable substantially in the direction of its own longitudinal axis.

Abstract: The blade angle of the blades of a rotary wing aircraft is adjusted by a control rod (5) inside the hollow rotor head operating a control shaft (8) extending radially out of the rotor head in axial alignment with the blade angle adjustment axis. The adjustment movement of the shaft (8) is transmitted to the respective blade (3.3) by a yoke (11, 12) and a torsion-stiff sleeve (7) which bridge the blade root (3.1) and the torsion yielding blade neck (3.2) respectively. The blade root (3.1) is connected to the rotor hub (1) by a forked member (2) through which a portion (11) of the yoke extends for connection to the control shaft.

Abstract: A helicopter power train is disclosed in which the rotor tip-path plane (218) inclination relative to the helicopter air frame (200) is achieved by blade flapping motions distributed through a plurality of drive train components rather than through blade flapping motion about a single flap hinge. Rotor tip-path plane flapping is accommodated by resilient transmission mounts (24, 25, 26 and 27) to the extent of approximately 25%, by a flexible mast (208) extending upward from a transmission (11) to the extent of approximately 20%, by a hub (213) having flexure members to the extent of approximately 50% and by flexible blade structure (214, 216) having beam bending to accommodate approximately 5% of the rotor flapping motion. The hub (213) comprises a plurality of yokes (260, 262) each of which is an elongated plate having flexure members to accommodate blade flapping. The yokes (260, 262) are stacked on the mast (208) to form the hub (213).

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 rotor system for a helicopter including a tension/torsion component which is fabricated from composite material and as a compound curved, continuous loop twin tension/torsion beam. Each end of the twin tension/torsion beam includes two curved (wrapped) ends which are oriented substantially orthogonally. At one end the curved ends extend about the flap hinge, and at the other end the curved ends extend about the fold and lead/lag hinge of the rotor system. To accommodate the twin tension/torsion beam at the flap hinge a support fitting is provided with lugs which are made compatible with the rotor hub lugs, and to accommodate the twin tension/torsion beam at the fold and lead/lag hinge a pitch varying structure is provided with twin beam engaging clevis surfaces.

Abstract: Rotary-wing aircraft rotor comprising a rigid hub coupled to the root of each blade in which a trailing return brace comprises a stack of metal plates alternating with plates of visco-elastic material the ends of which being coupled via a ball joint respectively to the root of one blade and to a place of the hub such that the brace is always slightly inclined.

Abstract: A helicopter rotor system with a plurality of identical rotor blades each of which includes a skin that forms an interior region, a counterweight rod and a bundle of longitudinally-extending fibers in the region. The bundle continues outside of the region, and there it includes a bight portion with a pair of arms and a bend. The fibers in the region are continuations of the fibers in the bight portion. A torque tube is attached to the counterweight rod, and a bearing stabilizes the torque tube relative to the mast, but does not transfer any appreciable centrifugal load. This bearing permits rotation (feathering) of the torque tube around its own axis, and lateral movement in any direction from the torque tube axis, around the center of this bearing (lead lag, and flapping). The bight portion is progressively shaped from a single flat portion bent directly around the mast, through a pair of separate channel sections to a bundle adjacent to the counterbalance rod.

Abstract: The wings of a hingeless helicopter rotor are secured to the head of the rotor by connecting elements of fiber compound materials. Each connecting element has at least two outer layers of fiber compound materials and an intermediate layer of .+-..beta.-fiber compound materials between the outer layers. The intermediate layer is bonded to the outer layers by a suitable adhesive. The intermediate layer takes up the central portion of the securing flange of the rotor head and its axial thickness increases radially inwardly. The intermediate layer has four side lobes which extend laterally out of the confines of the outer layers. These side lobes are connected by bolts to the rotor head. This structure provides a strong connection in which the outer layers are not weakened. Effects of the lead-lag movement of the rotor wings and of any torsion of the connecting elements are minimized and the fictitious hinges are located close to the rotational axis even within the zone defined by the rotor head flange.

Abstract: A helicopter rotor comprising elastomer joints, in which each blade is connected to a rotatable hub by means of a yoke constituted by a single U-shaped piece and mounted through a relative aperture provided in said hub;each yoke being connected to a transverse arm outwardly bordering said aperture, by means of a U stirrupembracing the relative said arm and provided with two overlying appendices extending outwards and having two surfaces inclined towards the other and acting as stop surfaces for two rocker arms constituting a devicefor controlling the flapping movements of said blade; said two rocker arms being mounted rotatable in a substantially vertical plane passing through the axis of the relative blade and being supported by a lever for controlling the pitch of this latter.

Abstract: Wind generator apparatus employs an induction generator with a wind-driven rotor. Connection of the induction generator to AC power lines is controlled by apparatus that compares generator rpm and line frequency. The rotor blades have a pretwisted, varying-chord inboard portion and an untwisted, constant-chord outboard portion. The blades are self-starting, operate efficiently over a range of wind speeds with constant pitch maintained by a torsional biasing mechanism, and pitch up automatically when the normal rpm operating range is exceeded. An improved blade-supporting spar of low torsional stiffness has an I-beam configuration with filament-wound flanges. A pitch damper prevents torsional oscillations while permitting the blades to pitch up readily. The rotor, which includes a teetering hub, is free to weather-vane about the axis of a supporting tower, but a yaw damper limits angular velocity. A guy wire and gin pole arrangement stabilizes the tower and permits easy raising and lowering of the tower.

Abstract: An elastomeric bearing assembly for supporting a rotor blade of a helicopter including a spherical elastomeric section mounted in serial relationship to a pair of frusto-conical elastomeric bearing section on the blade shaft. The frusto-conical bearing section includes two elastomeric bearings having bonded and alternate layers of elastomeric and non-extensible material and are arranged to receive the resulting force vectors in a direction normal to their planar surfaces.

Abstract: The invention relates to a rotary-wing aircraft rotor.The rotor comprises a hub 1 connected to each blade 7a by a rigid yoke 8-9 gripping the root of blade 7a and a spherical abutment 17 secured at its center C to radial arms 5a, 6a of hub 1 and bearing on its convex side against the inner end of yoke 8-9. According to the invention, an annular visco-elastic shock-absorber 20, constituting a frequency-matching device, is disposed between the yoke 8-9 associated with each blade 7a and the corresponding pitch control device 24-29.The invention is of use inter alia in the manufacture of fast helicopter rotors having a hub which is very compact and can therefore be easily streamlined.

Abstract: The wing blades of a helicopter rotor each are connected to the rotor hub a connection, e.g. a spar being .fwdarw..rarw. including a hinge which is at least fictitious to permit lead-lag movements of the blades <yielding relative to torsion to permit the blade angle adjustment>. A rod, which is stiff in the lead-lag direction and yielding against torsion, is connected in parallel to the connection between the blade root and the rotor hub. One connection of the rod is rigid, for example the connection to the blade root. The other connection of the rod is elastically yielding substantially only in the plane of the rotor whereby a substantial damping of blade movements in the lead-lag direction is accomplished.

Abstract: A connecting element for securing a rotor blade to the rotor hub of a helicopter rotor comprises at least two components arranged at an angle relative to each other. At least one component extends outside the boundary of the other component on both sides of the other component. Slots are arranged in at least one of the components and these slots extend substantially toward the shearing center or rather toward the central shearing axis. Additionally, each connecting element has a flattened zone adjacent to the rotor hub to function as a flapping hinge. The connecting element also functions as a lead-lag hinge and as a torsion hinge.