Abstract: The invention relates to a flapping restrainer device for the blades of a rotorcraft main rotor, and a rotor head comprising the same. The lower restrainers comprise a reciprocal star-shaped plate (32), having as many radial branches (33) as blades, and each one of the branches being engaged into a radial opening (6) of the hub (3). Outside the latter, the star-shaped plate (32) cooperates with supporting runners (47) integral with the blades. The upper restrainers comprise, for each blade, a stop which is retractable by the effect of the centrifugal force and which is composed of a lever (52), pivoting on a pivot (53) carried by the hub (3), and a first arm (55) of which constitutes a stop finger directed towards an upper supporting component (60) integral with the blade, while a second arm (56) carries a governor weight (57) and a nose (58) for support against a shoulder (59) integral with the hub (3).

Abstract: A turbine system utilizes the ebb and flow of the natural movements of tidal wave action to generate power. Waves are allowed to enter and exit from a chamber while at the top of the chamber a narrow exit allows for air flow into an out of the chamber is response to the water flow. A turbine placed in line with the air flow has pivoting blades that allows the turbine to rotate in one direction is response to the varying air pressures. This rotating turbine can be used to produce electrical power. An additional feature is an adjustable strike disc that limits the pivoting action of the turbine blades.

Abstract: A blade erection damper for a folding propfan blade comprising a blade hammer on the propfan blade engageable with a fluid-filled frangible capsule to dampen erection of the blade.

Abstract: An improved blade folding system for a propfan propulsion system comprises a fan blade journaled for rotation from a folded position substantially tangentially related to the housing of an engine to a radially extending run condition.

Abstract: A rotor, in particular a helicopter rotor, whereby the movement of the pitch angle of the rotor blade relative to a rotor hub is provided either by a blade neck with torsional flexibility disposed between a blade root and a blade wing or by a blade connection on a rotor hub arm with torsional flexibility. The pitch angle control for the blade is provided by a steering rod coupled to a torsionally stiff blade control casing extending coaxially without making contact along the blade neck or the rotor hub arm up to the blade wing or to the blade root. The control casing is supported on the blade root or rotor hub by at least one brace, which brace, in the longitudinal direction of the blade, has a T-shape. The vertical section of the T-shape is coupled to the blade control casing and the T-base is coupled with torsional flexibility to the blade root or the rotor hub arm, whereby the connection to the base is limited to both of the extremities of the base.

Abstract: A fluid apparatus comprising a motor, a blade wheel connected to the motor shaft, plural moving blades disposed along the outer circumference of the blade wheel with each moving blade shaft extending into the blade wheel and being rotatable relative to the blade wheel, small gears attached to the moving blade shaft inside the blade wheel, a large gear disposed to be level with the blade wheel so as to be geared with the small gears, an impeller connected to the large gear and housed in a casing with oil so that there may be produced a relative angle difference between the blade wheel and the large gear upon starting of the blower, and stoppers for stopping the large gear at predetermined positions with respect to the blade wheel at normal and reverse modes of the blower respectively.

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

Abstract: A multi-blade, variable pitch wind driven propeller in which a shock absorber is connected with each blade to dampen movement in both the radially inward and radially outward movements of the blade. Tension springs are connected with the blades to move them inwardly against centrifugal force, and in a preferred form of the invention, the tension spring has a variable rate so that it exerts greater resistance near its limit of outward travel. A coil compression spring may also be connected with each blade to absorb loads at the inner limit of travel of the blade and to impart an initial impetus to outward movement of the blade. In addition, retrofit lock nut means is provided for attachment to the ball stud connected to the butt end of each blade to extend along substantially the entire length of the stud and achieve a ratio of ball stud diameter, in inches, to rotor radius, in feet, of least as much as 0.100, thereby minimizing the risk of failure of the stud.

Abstract: A helicopter rotor blade supported by a flexbeam to be rotatable about an axis of rotation, in which a pitching motion thereof is allowable, is provided with a device for changing the pitch and damping the lead-lag motion thereof. The device comprises a bushing in a through hole formed at the inboard end of the flexbeam, an elastomeric pivot loosely fitted in the bushing, elastomeric dampers of cylindrical shape mounted on the upper and lower surfaces of the flexbeam and coupled with the upper and lower ends of the elastomeric pivot by means of nuts, and torque arms extending through the bushing and the elastomeric dampers and having the central portion thereof connected to central shafts of the elastomeric pivots. Each of the torque arms has both ends outwardly projecting beyond the elastomeric dampers and secured to a pitch sleeve which encloses the flexbeam.

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

Abstract: A major design consideration in helicopters is that of compensating for ssses on blades resulting from air forces during blade revolutions. Spinning rotor blades are severely stressed. To some degree conventional articulated helicopter rotor hubs overcome vibration difficulties, but high maintenance is a problem. Hingeless helicopter rotor assemblies, generally employing composite materials, were developed to overcome these obstacles. Such hingeless helicopter rotor assemblies usually include a rigid central hub member, and radial flexbeams rigidly attached to the hub member. Flexbeam rotors do not completely eliminate the dynamic instability difficulty. Even using these designs energy must be absorbed by damping means. The shear principle of damping is utilized in this invention.

Abstract: A tail rotor flapping hinge elastomeric bearing in which the inner and outer races are split and the races have ramped surfaces with the higher slope of the inner races being toward the outer edge of the bearing. The races have a plurality of slope angles and each inner race having a groove therein to facilitate a method of preloading.

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: 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.

Abstract: The invention relates to improvements in and relating to vertical axis wind turbines, particularly those of the "eggbeater" type. It has been found possible, in spite of previous beliefs that it was not so, to provide energy exchange means between the blades and the rotor to thereby smooth out cyclic variations in transmitted torque. The energy exchange means may be, for example, the provision of hinges between the blades and the rotor so that the blade is deflected in operation to transmit torque to the rotor in dependence not only on its fixed geometry but also in dependence on the deflection.

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 vibration isolator is formed with a spring mechanism and a fluid transmion mechanism interposed between a vibrating member and a support member. The fluid transmission mechanism includes a primary fluid chamber and a secondary fluid chamber, with the secondary fluid chamber being deformed to a greater extent than the primary fluid chamber as a result of vibrations. An inertia mass operatively associated with the secondary fluid chamber is displaced as a result of vibrations and is thereby accelerated with a resulting inertia force causing fluid pressure change in the fluid transmission mechanism which compensates as a dynamic force the dynamic portion of the spring force transmitted from the spring mechanism to the support member.

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 motion snubber comprises layers of elastomeric and substantially inextensible material stacked one on top of the other between a base and mounting plate, and is characterized by a rigid restraining pin disposed in a bore within the stack so as to restrain deformation of the elastomer. In one embodiment the bore is obliquely oriented with respect to the pin. In another embodiment the pin is contoured to accommodate angular motion.

Abstract: The invention provides a balance bar twin blade hub. A beam is formed of a tube made from a composite material of evolutive form whose section is cylindrical at its end on the blade side and progressively elliptical as far as its central connection part. It is connected to a support stirrup 2 conical stratified stops 4 forming balance bar bearings identical to the conical stratified stops forming the centrifugal force take up and angle of attack bearings providing the connection between the blade 16 and the beam.

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: A system for folding a helicopter rotor blade in which the lead-lag damper is mounted to the rotor blade spar, attached to the pitch housing and centered at the vertical pin flap hinge axis. This design of the lead-lag damper corresponding to a specially designed cam has a single actuator used to fold the rotor blade by sequentially engaging the cam with the actuator and lead-lag damper. Connected to the lead-lag damper is a lead-lag damper linkage assembly which is located in the operative position of the rotor blade so that flight loads are transferred directly to the pitch housing thereby uncoupling the actuator and cam from the path of these loads. In addition, this linkage is connected over center during blade folding so that the rotor blade cannot be back driven.

Abstract: The flapping stop device of the invention is intended for a gyroplane rotor comprising a hub (3) to which each blade (22) is connected by retaining and pivoting members (16) having two frames, one (17) of which is fixed to the hub (3) and the other (19) of which, in an internal radial position with respect to the first one, is locked for movement with the root (23) of the blade (22). The internal frame (19) has, projecting radially inwardly, at least one nose piece (29) having a stop surface and defining a convex cylindrical sliding surface (28) on the internal radial face of the frame (19). The nose piece or pieces (29) and the convex surface (28) cooperate respectively with one or more bearing surfaces (34) and a complementary concave surface (33) of a central stop (30) integral with the hub (3) or with the rotor mast (2).

Abstract: The integrated hub-mast (1) of the invention is composed of a tubular single piece body whose hub body forming part (3) is integral, on the side of its end end opposite the mast (2), with a reinforcing ring (5) and in which openings (6) are pierced. For each blade of the rotor, a stratified spherical stop (16) is fixed against the ring (5) and is retained in the hub body (3) and this stop (16) is also fixed to the ends integral to the hub body (3) of the lower (24) and upper (25) branches of a forked fastening part (23) connecting the blade (22) to the stop (16), the lower branch (24) passing through an opening (6) in the hub (3). A central flapping stop (30) is mounted on a support (31), in the hub-mast (1), which carries external fastenings for coupling to the resilient drag return and damping members of the blade.

Abstract: In a system having many unequal-area dampers (16) and a common main accumulator (34) for providing positive hydraulic pressure thereto, a shutoff valve (64) and a backup accumulator (62) are provided for each damper (16). In the event of a loss of pressure in the system, the shutoff valve (64) isolates each damper (16) and associated backup accumulator (62) from the rest of the system so that positive hydraulic pressure is provided to each associated damper (16).

Abstract: The invention shows a rotary positionable installation, such as a wind power, having a tower (11), and an apparatus carrier supported on the tower so as to be rotatable about its axis and rotary positionable by means of an azimuth drive unit, particularly a housing (2), including a frequency adjusting unit (18, 19 27; 40, 42, 46; 66, 74) for the natural yawing frequency of the swinging system of the following components: apparatus carrier (2), azimuth drive unit and tower (1) by adjusting the torsion (rotation) spring constant by means of one of the components and/or the connection between at least two of the components of the swinging system. In this manner, the adjustment of the natural yawing frequency is made possible in a simple manner in respect to construction as well as operation.

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 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: The energy converter includes a frame, a rotor mounted in the frame with a rotor shaft and vanes, and an element that can connect the rotor shaft to a generator, an alternator or another energy-converting mechanism. Each vane has a holder, a plurality of blades which hinge in the holder about small axes which lie in parallel relationship with the rotor shaft, and stops for the blades. The blades are a plurality of leaves which hinge on one another about axes which lie in parallel relationship with the rotor shaft. Stops limit the relative hinging motion of the leaves on the one hand to the position where they lie in extension of one another, and on the other hand to a position where the leaves form angles, for example in the range of 135.degree..

Abstract: Helicopter rotor on which each blade is connected in articulated manner to a center hub by means of a forkthe vertical plane movement of which, at rotor speeds below a given set value, is limited by a pair of limit rocker arms located between the hub and a ring nut mounted in rotary manner on the forkand rendered angularly integral with the hub by means of a compass drive.

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: Apparatus for damping blade lead/lag motion on a hingeless helicopter rotor assembly, including a hub, blades and flexbeam(s) interposed between the root end of the blades and the hub. Rigid, radial links extend the length of the flexbeams for attachment to the outboard ends thereof. Lead/lag motion at the outboard end of the flexbeam causes flexbeam bending, which is converted to radial translation of the links. This radial translation of the links and likewise the blade lead/lag motion is damped by damper means connected between the inboard ends of the links and the hub.

Abstract: A device comprising cyclic plates driven by flexible blades for controlling a helicopter rotor. The device comprises upper flexible curved blades pivotably mounted on the rotor shaft, above the rotary plate, and pivotably mounted by a ball joint on the rotary plate, so as to cause it to rotate with the rotor shaft and at least one lower flexible curved blade, pivoting on an element of the structure of the helicopter and pivotably mounted by a ball joint on the non rotary plate, so as to secure it against rotation. The transverse stiffness of the blades ensures centering of the plates whereas the longitudinal flexibility of the blades and their end pivot point allow the blades to follow the axial translational and tilting movements imparted to the plates by pilot controls pivotably mounted to the non rotary plate, and transmitted to levers controlling the angle of attack of the rotor blades by means of links pivotably mounted to the rotary plate.

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: Rotor tilt is permitted by two spherical elastomeric bearings, one above a hub member and one below, that have coincident centers at a tilt point (P) on the rotorshaft axis which is below the rotor plane. Positive rotor thrust is reacted by the upper bearing and negative rotor thrust is reacted by the lower bearing. Techniques for assembling the rotor system, precompressing the bearings, and limiting tilt are also disclosed.

Abstract: Hub moment and driving torque is provided for a helicopter gimbal rotor by two-part flat springs that are in-plane with the rotor tilt point (P). The inboard end of an outward part of each spring is connected to the rotorshaft and the inboard end of an inward part of the spring is connected to the tiltable hub member. The outboard ends of the two spring parts are journaled together by an eccentric elastomeric joint that allows for spring foreshortening that accompanies rotor tilt.

Abstract: The device comprises two rigid elements 1a, 1b, 2 and an elastomer mass 10 interposed therebetween so as to be deformed when the elements move relative to each other in a longitudinal direction. The device includes a closed space with a restriction element 16 defining two chambers 23, 24 whose volumes vary inversely upon movement of the chamber walls, the two chambers being interconnected by one or more passages, the empty space being filled with a viscous fluid material so as to produce a damping effect in the passages. Application to helicopter blade frequency adapters.

Abstract: Hub moment for a tilt rotor is provided by U-shaped springs that extend outwardly from the rotorshaft and in-plane with the tilt point (P) and inwardly to the tiltable hub member in the rotor plane, which is above the tilt point (P). Driving torque is supplied to the rotor via a torque disc that has a resilient diaphragm portion attached to the rotorshaft in-plane with the tilt point (P) and a rigid rim attached to the tiltable hub member in the rotor plane. The torque disc comprises the lower half of an aerodynamic fairing which encases the hub.

Abstract: A water wheel for operating fully submerged in an ocean current has a rotating frame member supported on the ocean floor for rotation about a vertical axis. The frame member supports a plurality of vertically extending vanes, each vane being rotatably supported on the frame for limited rotation about a vertical axis. It has a hydrofoil shape in cross-section with the axis of rotation parallel to the leading and trailing edges. Rotation of the vanes is limited relative to the frame by a hydraulic piston control system and shock absorbers.

Abstract: A rotor for helicopters, in which a central hub supports a plurality of radial blades connected thereto, each of which blade is provided with a surface rigidly connected to it and able to cooperate with respective abutment elements supported by the hub and movable with respect to this latter in a substantially horizontal plane to limit the oscillations of the respective blade in a horizontal plane between limits which are variable as a direct function of the angular velocity of the rotor itself.

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: 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: 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 wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.

Abstract: Helicopter rotor on which static balancing of the rotor is provided for by a number of annular-shaped counterweights housed inside each pin securing each blade to the hub; the said counterweights being supported by a rod pressed an clicked inside an axial hole on the relative pin.

Abstract: A device for controlling the cyclic and collective pitch of a helicopter rotor in which a fixed ring of an oscillating plate is maintained regularly fixed and is guided in its oscillations with respect to a drive shaft by a plurality of variable configuration supports uniformly distributed about the said drive shaft and connected to the said fixed ring by means of cylindrical pivots at least one of which is eccentric with respect to an axis rotation of an associated supported fork, which is perpendicular thereto.

Abstract: Disclosed is a wind-driven generator apparatus with variable pitch blades. The apparatus includes a yaw damping arrangement for resisting weathervaning rotation of a head assembly of the apparatus about a vertical axis and the apparatus further includes a pitch control mechanism for the blades which maintains the pitch substantially constant during normal operating r.p.m. of the blades but allows the blades to pitch up in an overspeed condition, and a brake mechanism for the generator shaft which includes an adjusting mechanism that compensates for wear in the brake.

Abstract: Disclosed is a wind-driven generator apparatus with variable pitch blades. The apparatus includes a yaw damping arrangement for resisting weathervaning rotation of a head assembly of the apparatus about a vertical axis and the apparatus further includes a pitch control mechanism for the blades which maintains the pitch substantially constant during normal operating r.p.m. of the blades but allows the blades to pitch up in an overspeed condition, and a brake mechanism for the generator shaft which includes an adjusting mechanism that compensates for wear in the brake.

Abstract: A helicopter rotor in which a central plate-like hub is provided with a plurality of axial apertures uniformly distributed around a central axis of rotation and each defined radially outwardly by a supporting peripheral bridge connected to a respective blade by a U-shape structure extending through the said aperture and coupled to the associated bridge by an elastomeric coupling; each U-shape structure being coupled to a respective radial projection of the hub by a further elastomeric coupling.