Abstract: A piston assembly for a lead-lag damper for a blade mounted on a rotor of a helicopter includes a piston-rod that has an inside surface and a piston-head that extends radially outward therefrom. The piston-rod has two ports extending therethrough on opposing sides of the piston-head. A sleeve is positioned in the piston-rod and has two annular passages that communicate with the respective ports. A valve spool is disposed in and slidingly engages the sleeve. The valve spool has a channel which is in variable fluid communication with two passages. The piston assembly includes a biasing member that biases the valve spool axially away from it. The channel has an axial width configured to variably regulate fluid flow between the two ports to control dampening of the piston-rod in response to centrifugal forces applied to the valve spool.

Abstract: Provided is a vertical axis wind power generation device including a wind turbine of a vertical axis type including a support column, a main shaft disposed on an upper portion of the support column so as to be rotatable, a plurality of blades coupled to the main shaft through arms; a power generator; and a container having a standard dimension for freight transport. The wind turbine is accommodatable in a folded or disassembled state in the container together with the power generator. The container is provided with a support-column fixing part configured to fix the support column of the wind turbine to the container. The container may include an inclining mount inside the container, the inclining mount being configured to accommodate a folded body of the wind turbine.

Abstract: A damper assembly includes a housing defining at least one or more cavities. A piston is in operable communication with the housing. A rod end is operatively coupled to the piston, the rod end having at least two cartridges.

Abstract: A spherical bearing centrifugal force retention link includes an inboard spherical bearing to attach to a rotor hub and an outboard spherical bearing to attach to a rotor blade. In use, the inboard spherical bearing and the outboard spherical bearing react centrifugal force radially and a torsional moment of the centrifugal force link is substantially constant throughout the rotor blade pitch range.

Abstract: A rotor hub is presented that uses a low profile and frontal area design that reduces drag and combines the advantages of utilizing a virtual flapping hinge and a soft in-plane rotor hub.

Abstract: An aircraft rotor assembly has a yoke and a plurality of rotor blade assemblies coupled thereto. Each of the rotor blade assemblies include a rotor blade, a bearing, and a blade grip coupling the rotor blade to the bearing. Each of the rotor blades is rotatable about a lead-lag axis, flap axis, and a pitch change axis, wherein all the axes intersect within the bearing. Adjacent pairs of rotor blade assemblies are coupled together via a damper assembly that is coupled to the pitch change axis of each of the rotor blade assemblies.

Abstract: A bearing assembly is for movably coupling first and second members and includes first and second laminated bodies disposed within the second member bore, spaced about a centerline and connected with the first member. The first laminated is formed of alternating, arcuate first elastomeric laminae and arcuate first rigid laminae nested generally about a first central axis, each first rigid lamina having a first radial thickness between inner and outer surfaces. The second laminated body is formed of alternating, arcuate second elastomeric laminae and arcuate second rigid laminae nested generally about a second central axis, each second rigid lamina having a second radial thickness between the rigid lamina inner and outer surfaces. The first radial thickness of the first rigid laminae is substantially greater than the second radial thickness of the second rigid laminae such that the second laminated body has a substantially lesser stiffness than the first laminated body.

Abstract: A rotor blade assembly for a tiltrotor aircraft comprising a rotor blade pivotally connected to a yoke with dual concentric blade bolts having a common central axis providing a pivotal axis inboard of an outboard CF bearing and the yoke tip. In use, the compact folded arrangement of the rotor blades reduces folded aircraft dimensions in response to ever increasing restricted storage space parameters.

Abstract: In one embodiment, a rotor hub comprises a hub body, and a plurality of blade grips configured for attaching a plurality of rotor blades. The rotor hub further comprises a plurality of centrifugal force bearings coupled to the plurality of blade grips, wherein a focus of the plurality of centrifugal force bearings is aligned with a centerline of a rotor mast. The rotor hub further comprises a plurality of drive links configured to transfer torque to the plurality of rotor blades, wherein the plurality of drive links is positioned to correspond with a leading edge side of the plurality of rotor blades. The rotor hub further comprises a plurality of pitch horns configured to adjust a pitch of the plurality of rotor blades.

Abstract: An aircraft rotor assembly has a central hub and a plurality of rotor blades coupled to the hub for rotation with the hub about an axis, each blade having a Lock number of approximately 5 or greater. A lead-lag pivot for each blade is formed by a flexure coupling the associated blade to the hub. Each pivot is a radial distance from the axis and allows for in-plane lead-lag motion of the associated blade relative to the hub, each pivot allowing for in-plane motion from a neutral position of at least 1 degree in each of the lead and lag directions. Elastic deformation of the flexure produces a biasing force for biasing the associated blade toward the neutral position, and the biasing force is selected to achieve a first in-plane frequency of greater than 1/rev for each blade.

Abstract: An aircraft rotor assembly has a central yoke and a plurality of rotor blades coupled to the yoke for rotation with the yoke about an axis, each blade having a Lock number of approximately 5 or greater. A lead-lag pivot for each blade is a radial distance from the axis and allows for in-plane lead-lag motion of the associated blade relative to the yoke, each pivot allowing for in-plane motion from a neutral position of at least 1 degree in each of the lead and lag directions. Lead and lag motion of each blade is opposed by a biasing force that biases the associated blade toward the neutral position, and the biasing force is selected to achieve a first in-plane frequency of greater than 1/rev for each blade.

Abstract: A rotor carrying a plurality of lift assemblies, each having a retention and mobility member. An abutment mechanism of a lift assembly includes an abutment track arranged on the retention and mobility member and a single cylindrical abutment that is movable in pivoting about a movement axis, said abutment extending over a height in elevation and also over a length and over a width. The length is greater than said width, and said height is greater than said length. A fly-weight is secured to pivot with said abutment, and a return spring exerts a force on said fly-weight.

Abstract: A method for controlling helicopter ground resonance and air resonance motions as well as centrifugal force switching dampers are disclosed. A helicopter lead-lag damper (30) has a first ground resonance motion damping rate stage (FDR) and a second air resonance motion damping rate stage (SDR). The damper (30) includes a centrifugal force switch (52). The damper (30) is oriented relative to the rotary wing rotation axis (26) and helicopter blade (24). An in-flight rotation rate of the centrifugal force switching damper (30) actuates the centrifugal force switch (52) with the damper switching from the first ground resonance motion damping rate stage (FDR) to the second air resonance motion damping rate stage (SDR).

Abstract: Damper device for damping relative movements of two elements of a mechanical system. The damper device comprises a damping chamber filled with a hydraulic fluid, a rod (4) having a piston (3) movable in the damping chamber so as to define two hydraulic compartments (1, 2), at least one calibrated orifice (10) provided in the piston (3) for throttling the hydraulic fluid flowing from one hydraulic compartment (1, 2) to another hydraulic compartment, at least one compression peak-limiting valve (11) and a traction peak-limiting valve (12), throttling the hydraulic fluid flowing from one hydraulic compartment (1, 2) to another hydraulic compartment. The damper has additional hydraulic means that are active in compression and in traction when the piston (3) reaches the end of its stroke, so as to constitute a progressive hydraulic abutment damping the end-of-stroke jolts.

Abstract: A frequency adapter for a rotorcraft rotor is provided. The frequency adapter has at least first and second cylinders having respective elongate first and second side walls, respectively. The second cylinder is surrounded at least in part by the first cylinder. Resilient return rings are in contact with the first and second side walls. The return rings comprise resilient first and second extreme layers each in contact with the first and second side walls. The adapter is provided with a fluid arranged in a single chamber between the first and second extreme layers.

Abstract: A rotor assembly includes a yoke operably associated with a rotor blade. The yoke includes a first device and a second device that attach the rotor blade to the yoke. The first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis. The second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis. The method includes rotating rotor assembly about a first plane of rotation, while retaining a relatively stiff out-of-plane rotation and a relatively soft in-plane rotation during flight.

Abstract: A blade speed control apparatus and method. The apparatus includes a rotor assembly a first blade assembly movably attached to the rotor assembly at a first initial position, a second blade assembly movably attached to the rotor assembly at a second initial position, and a movement mechanism configured to move the rotor assembly in a first lateral direction along a y-axis such that a first angle exists between the first blade assembly with said respect to the second blade assembly. The movement mechanism is configured to move a portion of the rotor assembly in a first lateral direction along a y-axis such that a first angle exists between the first blade assembly with said respect to the second blade assembly. The first angle does not comprise an angle of 180 degrees.

Abstract: A hub assembly for a tilt rotor includes a yoke having a plurality of yoke arms located substantially orthogonal to a central axis of the hub assembly. An inboard pitch change bearing assembly substantially surrounds a yoke arm of the plurality of yoke arms. An outboard pitch change bearing assembly is located at the yoke arm. The inboard pitch change bearing assembly and the outboard pitch change bearing assembly are operably connectable with a rotor blade to allow pitch change of the rotor blade relative to the yoke about a pitch change axis.

Abstract: A rotor system has a rotor, an axis of rotation about which the rotor may be rotated, a linkage system having a first adjustable length portion and a second adjustable length portion, wherein the second adjustable length portion is configured to provide a relatively finer adjustment of an overall effective length of the linkage system as compared to the first adjustable length portion and wherein the rotor is configured to rotate about the axis in response to changing the overall effective length of the linkage system.

Abstract: An aircraft rotary wing motion control fluid device providing motion control and with wireless sensing of at least one fluid property inside the fluid device is provided. The wireless sensing system is integrated with at least one of the first and second aircraft rotary wing motion control fluid device bodies. The wireless sensing system includes at least one fluid property sensor in sensing proximity to the at least one fluid chamber and a communications device for wirelessly conveying a measurement made by the at least one fluid property sensor to a remote location.

Abstract: The present invention relates to a damper (10) provided with an inner end strength member (20) and an outer end strength member (30) that are tubular and coaxial, a return member (40) being arranged between the inner end strength member (20) and the outer end strength member (30). The return member (40) includes an intermediate strength member (43) coaxial with the inner and outer end strength members (20, 30), said return member (40) having first and second return means (41, 42), said first return means (41) being arranged between the outer end strength member (30) and said intermediate strength member (43), said second return means (42) being arranged between the inner end strength member (20) and said intermediate strength member (43).

Abstract: A rotorcraft rotor fitted with a device for damping lead-lag oscillations of the blades (2) of the rotor. The blades (2) are hinge-mounted on a rotary hub (1) of the rotor via respective sleeves (3). The damper device comprises a set of dampers (6), each individually housed in a respective one of said sleeves (3) and deformable between two fastening points (8, 9), one with the sleeve and the other with an engagement member (7) for engaging the hub (1) via a linkage (10). For each of the sleeve (3), the damper (6) housed by a given sleeve (3) is in hinged engagement with the linkage (10) via a lever arm (11) hinged to the sleeve (3).

Abstract: A wind mill structure of a lift-type vertical axis wind turbine. The lift-type vertical axis wind turbine includes a vertical shaft and the wind mill includes a plurality of blades and supporting arms. The supporting arms hold the blades, and the blades are connected to the vertical shaft via the supporting arms. A setting angle, formed by a chord of the blades and a tangent line that goes through the center of the blades, ranges from ?12° to 12°. An angle, formed by the chord of the blade and the rotatable supporting arm, ranges from 7° to 100°. The wind mill can maintain relatively stable rotation speeds under wind speeds exceeding the rated wind speed by adjusting the angle of the supporting arms, thereby ensuring stable output from the vertical axis wind turbine.

Abstract: A rotor hub has a yoke with radial arms allowing flapping of connected blades about a flap axis. A grip is rigidly attached to each blade, and a lead-lag bearing connects each grip to one of the arms, the bearing defining a lead-lag axis outboard of the flap axis. Each arm has a pair of straps located on opposite sides of the rotor plane for transferring centrifugal force from the blades to the central portion of the yoke. A pair of lead-lag dampers is provided for each grip, the dampers of each pair being located on opposite sides of the rotor plane and connecting an inboard end portion of the grip to the adjacent strap. In-plane motion of a blade causes rotation of the attached grip about the lead-lag axis, causing opposite motion of an inboard end portion of the grip. The dampers act to oppose rotation of the grip.

Abstract: A rotor hub assembly and method for controlling movement of a rotor blade relative to a swashplate. The hub assembly having an attachment device operably associated with the rotor blade and the swashplate. The attachment device provides pivot and rotational blade movement relative to the swashplate. A dual spring-rate damper is operably associated with the attachment device. The damper switches between a first spring rate and a second spring rate during flight to control movement of the rotor blade. The method includes the process of switching the damper between the first spring rate and the second spring rate during flight.

Abstract: The rotary damper for controlling helicopter motions includes an outer canister with an inner paddle wheel receiving cavity which receives an inner paddle wheel with upper and lower elastomeric tubular intermediate members between the inner paddle wheel and the outer canister. The canister and inner paddle wheel form neighboring variable volume chambers in liquid communication through liquid damping conduits. A clockwise rotation of the inner paddle wheel about the center of rotation axis relative to the outer canister pumps damper liquid from a second variable volume chamber through a first liquid conduit towards a first variable volume chamber, and a counterclockwise rotation of the paddle wheel relative to the outer canister pumps the damper liquid from the first variable volume chamber through the first liquid conduit towards the second variable volume chamber with the elastomeric tubular intermediate members providing for the relative rotation and containing the damper liquid in the damper.

Abstract: A blade support limb structure of a vertical axis wind power generator includes a fixed support limb (1) and a rotatable support limb (2), one end (21) of the rotatable support limb is connected with one end (22) of the fixed support limb and the rotatable support limb may rotate around it. The structure keeps a wind wheel at stable rotation speed in the case the environmental wind speed exceeds the rated wind speed, thereby to ensure that vertical axis wind power generator outputs constant power. The structure solves a problem of constant power output of the vertical axis wind power generator from hundreds watts to thousands watts, so its applications are wide.

Abstract: Described is a blade (10) extending longitudinally from a root (11) of the blade (10) to a free end (12) of the blade (10), the blade (10) being provided with an incorporated resonator (20) for reducing the drag movements (F1, F2) of the blade (10), the resonator (20) being provided with a closed tank (30) that is partially filled with a liquid (50). Furthermore, the resonator (20) includes a central tube (40) immersed inside the tank (30), the tank (30) and the central tube (40) being arranged in a longitudinal direction (Y) of the blade (10), the central tube (40) having first and second ends (41, 42) that communicate with the tank (30) so that the liquid (50) can move from the tank (30) into the central tube (40), and vice versa.

Abstract: A rotor system includes a multiple of rotor blade yokes mounted to a rotor hub. A lead/lag damper is mounted to each of the rotor blade yokes and to a damper hub. An actuator system is operable to shift a damper hub axis of rotation relative the rotor axis of rotation to minimize 1P damper motions. A method of minimizing 1P damper motions within a rotor system includes shifting the damper hub axis of rotation relative the rotor axis of rotation to oscillate an inner connector of each lead/lag damper in phase with a 1P blade motion to minimize the 1P motion of the damper.

Abstract: A frequency adapter (1) having at least first and second cylinders (11, 12) having respective elongate first and second side walls (13, 14), the second cylinder (12) being surrounded at least in part by the first cylinder (11), resilient return means (20) being in contact with the first and second side walls (13, 14). Said return means (20) comprise resilient first and second extreme layers (21, 22) each in contact with the first and second side walls (13, 14), said adapter (1) being provided with a fluid (30) arranged in a single chamber (100) between said first and second extreme layers (21, 22).

Abstract: An electronic lead/lag damper algorithm implemented as part of the fly-by-wire flight control system to minimize or eliminate mechanical lead/lag dampers of a rotary wing aircraft. The electronic lead/lag damper algorithm uses a cross-feed control methodology that band-pass filters pitch and roll rates and feeds back a signal to the lateral and longitudinal cyclic inputs to provide electronic stability to rotor lag modes.

Abstract: The invention relates to a rotorcraft rotor comprising a hub and at least two blades hinged relative to the hub about respective pitch axes and about respective flap axes, and about respective lag axes; each blade is secured to a respective pitch lever; the rotor includes a respective pitch control rod connected to each pitch lever by a first ball joint, and a common lag damper system centered substantially on the axis of rotation of the rotor and connected to each of the blades; the damper system is secured to a respective lateral projection from each blade via a respective second ball joint that is sufficiently close to the first ball joint connecting the pitch rod to the pitch lever for the lag damper system to be relatively insensitive to flap oscillations of the hinged blades.

Abstract: A water turbine powered electrical generation system is disclosed. The generation system includes a water-driven turbine completely submerged below a flowing water source. The flowing water source rotates the turbine, which is coupled to an electrical generator. The electrical generator generates electrical power for distribution away from the electrical generation system. The electrical generation system may be located on a floating or submersible platform.

Abstract: A wind turbine generator, an active damping method thereof, and a windmill tower in which vibrations of the wind turbine generator itself or the windmill tower can be reduced at low cost are provided. The acceleration due to vibrations of a nacelle (13) is detected with an accelerometer (17) attached to the nacelle (13). In an active damping unit (20), a pitch angle of windmill blades (12) for generating a thrust on the windmill blades (12) so as to cancel out the vibrations of the nacelle (13) is calculated on the basis of the acceleration, and the pitch angle is output as a blade-pitch-angle command ??* for damping. On the other hand, in a pitch-angle control unit (30), a pitch angle of the windmill blades (12) for controlling the output to be a predetermined value is calculated, and the pitch angle is output as a blade-pitch-angle command ?* for output control. The blade-pitch-angle command ??* for damping is combined with the blade-pitch-angle command ?* for output control using a subtracter (40).

Abstract: A damper assembly including a spherical elastomer bearing member, wherein the spherical elastomer bearing member is operable for accommodating relative motion and/or vibration, and a flat elastomer bearing member, wherein the flat elastomer bearing member is operable for accommodating relative motion and/or vibration. The damper assembly also including a substantially rigid transition shim disposed between the spherical elastomer bearing member and the flat elastomer bearing member, wherein the substantially rigid transition shim is operable for coupling the spherical elastomer bearing member to the flat elastomer bearing member. The damper assembly further including a tension member attached to the substantially rigid transition shim, wherein the tension member is operable for precompressing the spherical elastomer bearing member and increasing the cocking stiffness of the damper assembly.

Abstract: A drag damper for use on a rotary wing aircraft rotor comprises a body defining two variable volume chambers linked by a piston. The chambers are filled with fluid and are connected by a restriction port (35) and by a channel (32) of larger cross-section than the restriction port. A secondary piston slidable and pressure-tight piston is fitted in the channel and loaded by an elastic bias (34). The equivalent mass of this secondary piston (33) and of the fluid which it displaces, and the stiffness of the elastic bias (34) are such that the secondary piston is resonant in the channel (32) at the rotation frequency of the rotor, to filter the dynamic component at this frequency of stresses applied to the damper (20).

Abstract: A drag damper for use on a rotary-wing aircraft rotor comprises a body defining two variable volume chambers linked by a piston. The chambers filled with fluid in the damper are connected by a restrictor port in the piston or between the latter and the body, and via a channel of great length and small cross-section compared with the cross-section of the body, in which elastic means bear against and load the piston-rod assembly towards a neutral position, the anti-resonance frequency of the damper being matched substantially to the nominal rotation frequency of the rotor, and the restrictor port providing effective damping at the natural frequency (&ohgr;&dgr;) of the blades in drag, differing by construction from the rotor frequency (&OHgr;).

Abstract: Helicopter blades each have a piston connected to it. The pistons are movable within a cylinder between innermost and outermost positions. The hydraulic fluid of each cylinder is connected to other cylinders by a hydraulic tube or through a manifold. A drive bar moving synchronously with the blades is connects to the cylinders. As the helicopter moves in flight the force of the wind against a blade causes a piston to move inwardly. This causes fluid to be expelled from the cylinder into the another cylinder by way of the hydraulic tube causing other piston to be moved outwardly. Meanwhile the other piston, because it is moving with the wind, is exerting an opposite effect on the other piston. The result is a tendency for the blades to approach an equilibrium condition with respect to the wind forces to minimize the shocks to the overall system.

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: The device comprises, between two blades and their members linking them to the hub, three levers articulated by ball joints to the members and to the hub, the two levers pivoting on the third one about axes of pivoting parallel to each other and perpendicular to the common plane passing through the centres of the ball joints. At least one of the levers comprises at least one drag damper.

Abstract: A main rotor is provided for use in a rotary winged model aircraft. The main rotor includes a rotor hub assembly rotatable about a vertical axis and at least two main rotor blades. Each of the main rotor blades extends in a radial direction from the rotor hub assembly. The main rotor blades each include a tip end positioned to lie in spaced-apart relation to the rotor hub assembly and a root end coupled to the rotor hub assembly for pivotable folding movement from an initial horizontal position perpendicular to the vertical axis about a horizontal axis through a desired folding angle of about 90.degree.. Forces transmitted to the rotor hub by the rotor blade during a crash-landing of a rotary winged model aircraft including the main rotor are minimized due to movement of the rotor blades through the desired folding angle.

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 hollow rotor hub is provided at the top of the rotor shaft for a multi-bladed helicopter. The blades being mounted to the rotor hub on spherical elastomeric bearings which provide for coincident rotor blade hinges for blade pitch, flap and lead-lag motions. The invention discloses a lead-lag damper contained in a housing at the center of the hollow rotor hub. The damper consists of a series of damping plates, each plate being connected to one of the rotor blades. The damping plates are separated from each other and from the damper housing by elastomeric layers bonded to the plates and to the housing. Lead-lag damping is provided by the shear in the elastomeric layers. The damper may be fastened to the air frame in a conventional manner, it may be mounted on a spindle for rotation about the rotor axis independent of rotor shaft rotation or may be free-floating and attached only to the rotor blades and not to the rotor shaft.

Abstract: Gyrocraft rotor hub body (1) in which each blade (2) is linked to the body (1) by articulations and linking members the body includes two strong elements (7, 8) whose planes are substantially parallel to each other and perpendicular to the axis of the mast (3) of the rotor. The two elements (7, 8) are separated from each other by a space which is of sufficient size to permit the housing of the articulations which are advantageously embodied in the form of laminated spherical stops (5), one of the armatures (16) of which moves integrally with the (17) is fixed with respect to the two elements of the hub body and is arranged in the vicinity of the periphery of these elements so as to constitute a rigid bracing.

Abstract: A rotor head for a rotary wing aircraft rotor blades, such that each blade is coupled to the hub by an attachment assembly. The attachment assembly includes a thrust bearing 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 hydro-elastic elements which are pivotable with respect to each other about a common axis. The damping device as also disposed to pivot in a flapping direction of the blade through a pivot joint.

Abstract: The hydraulic damper according to the invention has at least one restricted communication passage (47) between its two working chambers (8, 9) whose cross section is controlled by a viscous restriction valve (51) positioned via a control pressure of a fluid of a control damper with at least one secondary chamber (41, 42) delimited in a secondary cylinder (39) by a control piston (40), which cylinder and control piston are integrally attached, one to the main body (1), the other to the damping piston (4) of the damper, such that the damping law of the control fluid positioning said valve (51) is linked to the relative displacements of the main body (1) and damping piston (4).Application to the equipping of elastic-return struts with integral damping, in particular for helicopter rotors and blades. FIG. 2.

Abstract: A device of retractable stops for the blades of articulated rotors for giroplanes, which includes a stationary stop 20 with a finger 22 radially converging towards the exterior and externally radially protruding on the external spar 9 of the articulation means 7 of each blade on the hub 3, as well as a movable stop 21 with a receptacle 36 resiliently returned by a return device 45 in a position fit around the finger, but disengaged from the finger by centrifugal force when the rotation speed of the blades is higher than a set value. The invention therefore provides absolute stops in flapping and drag in the "ground" position and sharp stops in the flight position. One advantageous application is for helicopter rotors.

Abstract: A viscous damper for a helicopter rotor blade having a stator member and a rotor member each having a plurality of flanges of different diameter defining cylindrical internal and external shear surfaces, respectfully, and a shear gap therebetween, one stator member internal shear surface having two diameters, the shear gap distances between proportional to radius, and a coaxial rotor member comprising two discs having outer cylindrical shaped shear suraces forming a shear gap with adjacent stator member shear surfaces and one rotor disc being axially movable so that a variable portion of its shear surface is opposite both of the diameters of the stator member two-diameter internal shear surface.

Abstract: A helicopter rotor on which each blade is connected in articulated manner to a center hub by means of a fork, the vertical plane movement of which is limited, below a given speed of the rotor, by a pair of limit rocker arms located between the hub and a ring nut mounted for rotation on the fork and angularly integral with the hub by means of a rod of variable length connected in articulated manner to a slide supported on the hub and arranged substantially horizontally and crosswise in relation to the blade.