Abstract: An improved electrically powered rotorcraft is of the type having a rotor including a rotor hub and a pair of rotor blades mounted to the rotor hub on opposite sides thereof, the rotor being rotatably mounted on a primary drive shaft, and a rotary electric motor coupled to the drive shaft. In this rotorcraft, the improvement includes a common pitch-angle shaft coupled to each of the blades; a limited-angle electric motor, mechanically coupled to the common pitch-angle shaft, and configured to cause rotation of the common pitch angle shaft and therefore adjustment of pitch of the pair of rotor blades; and a controller system in communication with the limited-angle electric motor, configured to provide cyclic control of pitch of the pair of rotor blades.

Abstract: A wind turbine (1) comprising a tower (2), a nacelle (3) and a hub (7) is disclosed. The hub (7) comprises a blade carrying structure (4) with one or more wind turbine blades (5) connected thereto. Each of the wind turbine blades (5) defines an aerodynamic profile having a chord which varies along a length of the wind turbine blade (5). Each of the wind turbine blades (5) is connected to the blade carrying structure (4) via a hinge (6) at a hinge position of the wind turbine blade (5), each wind turbine blade (5) thereby being arranged to perform pivot movements relative to the blade carrying structure (4) between a minimum pivot angle and a maximum pivot angle. The hinge position is arranged at a distance from the inner tip end (5a) and at a distance from the outer tip end (5b), and the chord at the hinge position is larger than or equal to the chord at the inner tip end (5a) and larger than the chord at the outer tip end (5b).

Abstract: A rotor blade assembly of an aircraft having a rotor hub including a structural member having an inboard end and an outboard end, the structural member being connectable with the rotor hub. A spar surrounds the structural member and extends at least partially along a rotor blade axis. A pitch bearing assembly supports the spar relative to the structural member. The pitch bearing assembly includes an inboard pitch bearing mounted to the inboard end of the structural member and an outboard pitch bearing mounted to the outboard end of the structural member. The rotor blade assembly additionally includes a centrifugal assembly including a centrifugal bearing disposed between the inboard pitch bearing and the outboard pitch bearing relative to the rotor blade axis.

Abstract: A rotor blade for a rotary wing aircraft includes a rotor hub including a first flex-beam attachment member and a flex-beam assembly. The flex-beam assembly includes a flex-beam support member having an attachment end and a wrapping end. A first flex-beam includes a first end, a second end and an intermediate portion. The first end of the first flex-beam is connected at the first flex-beam attachment member and the second end of the first flex-beam being connected to the attachment end of the flex-beam support member. A second flex-beam includes first end portion, a second end portion and an intermediate section. The first end portion of the second flex-beam is connected at the first flex-beam attachment member, the second end portion of the second flex-beam being connected at the second flex-beam attachment member and the intermediate section extending about the wrapping end of the flex-beam support member.

Abstract: A ram air turbine (RAT) in which a cam follower is operably coupled to turbine blades such that a cam follower position determines turbine blade pitch.

Abstract: A rotor wing in a fiber-reinforced composite design including fiber layers, in particular for a tail rotor of a rotary wing aircraft, with a rotor blade (1) that includes a blade skin (40, 50) and a blade body (41-57) that includes an aerodynamically effective profile, with a tension-torque-transmission element (3) connected to it, which is designed in one piece with the rotor blade (1), and with fiber layers (42-47) that extend through the tension-torque-transmission element (3) and are scarf-join in the rotor blade (1), is improved in that the fiber layers (42-47) extend right through from the tension-torque-transmission element (3) to the blade body (41-57). Furthermore, a method for producing the rotor wing is described.

Abstract: A stiff in-plane gimbaled rotor head for a rotorcraft, such as a helicopter, includes a vertically extending rotor shaft, a center hub disposed on the rotor shaft for conjoint rotation therewith, and an outer hub surrounding the center hub and coupled thereto through a spherical gimbal bearing for conjoint rotation therewith, and such that the outer hub is also capable of an angular range of gimbaling movement relative to the center hub. A plurality of rotor blades, which may include three or more blades, is coupled to the rotor shaft through the inner and outer hubs by a constant velocity joint that enables the blades to be rotated in a common plane about the axis of the rotor shaft while controlling the respective pitches of the blades and such that any other relative in-plane and out-of-plane movements of the blades during rotation is prevented.

Abstract: A blade for an antitorque tail rotor of a helicopter, having a leading edge and a trailing edge opposite each other and elongated along a longitudinal axis of the blade; the trailing edge, in use, interacts with the air current after the leading edge; the blade also has two opposite surfaces extending between the leading edge and the trailing edge, and a root portion extending from a radially inner first end, with respect to a rotation axis of the blade, towards a second end opposite the first end; and the root portion, when sectioned in a plane perpendicular to the leading edge and trailing edge, has a profile asymmetrical with respect to a chord joining the leading edge and trailing edge.

Abstract: A vane assembly for a gas turbine engine, the assembly including a plurality of vanes 14 with an asymmetric organic metal/ceramic matrix composite lay up, such that when the vanes 14 are placed in tension or compression the profile of the vane 14 will alter by twisting or untwisting. Other materials may be provided for the vanes 14, and/or other methods may be used for placing the vanes 14 in tension or compression to provide positive changes to the profile thereof.

Abstract: A tail rotor hub system and methods are disclosed. In one embodiment, the system includes a helicopter fuselage connected to a tail rotor assembly that holds tail blades. The assembly includes an elongated tail rotor housing and an elongated blade root fitting that rotates within the housing. A tension torsion strap is connected at one end to the housing and is connected at its other end to the blade root fitting to hold the blade root fitting in the housing when the housing rotates. Coupled between outside walls of the blade root fitting and inside walls of the housing are self lubricating bearings to enable the blade root fitting to rotate within the housing to change the pitch of the tail blades.

Abstract: Rotor apparatus and methods for vertical lift aircraft are disclosed. In one embodiment, a bearing assembly adapted for rotatably coupling a rotor blade to a support member includes an inner housing annularly disposed about a portion of the support member, an outer housing annularly disposed about at least part of the inner housing and is rotatably coupled to the inner housing by an annular bearing device, and a flexible member adapted to be coupled to the support member and including an engagement portion adapted to engage the outer housing and to at least partially relax a side force exerted on the annular bearing device by a bending of at least one of the rotor blade and the support member.

Abstract: A spacer arrangement 1, 40 is provided in which wedges 5, 6; 45, 46 are arranged to have an interface 7, 47 between them such that a thermally variable member 8, 48 can cause relative motion between the wedges 5, 6; 45, 46 to adjust an arrangement lateral dimension dependent upon temperature. In such circumstances with the arrangement 1, 40 positioned within a gap 3 between a casing 14 and unison ring 13, retention of position of that unison ring 13 can be maintained. The unison ring is arranged to adjust position of variable vanes.

Abstract: A cooling fan comprising a fan housing and a plurality of blades rotatably disposed within a conduit through the fan housing. Each of the plurality of blades extends radially outward from a hub to a tip. The radial gap between the tips of the blades and the conduit defines a tip clearance. The cooling fan further comprises an tip clearance reduction system operable to control the tip clearance.

Abstract: A hingeless rotor, in particular for a rotorcraft, comprising: a rotor head, a rotor mast having a rotor axis, a torque-transmission element nonrotatably joined to the rotor mast, at least one rotor blade, and a rotor-head-side rotor-blade connector having a centrifugal-force-discharging blade connector loop, which loop encircles the rotor axis or the rotor mast and is nonrotatably joined to the torque-transmission element.

Abstract: The blade includes a current part (1) having an aerodynamic profile enclosing a spar (7) and extending from blade tip (4) to a blade root (3) provided with a pitch sleeve (21), through which twisting arm (6) passes and protrudes beyond blade root (3), and having a first part of a bundle (5) of superimposed and elongated metal strips, current part (1) including a block (13) based on synthetic material molded in form in a single piece around spar (7), and a second part of bundle (5) extending in line with the first part forming the twisting arm (6) and cooperating with the anchoring devices (14, 17) of the block (13) based on synthetic material around the spar (7).

Abstract: A submarine countermeasure vehicle includes an elongated body for supporting a countermeasure device, and a propulsion assembly mounted on an after end of the body. The propulsion assembly includes a rotatable propeller hub, propeller blades mounted on the hub and moveable between a first position wherein the blades extend substantially radially outwardly from the hub, and a second position wherein the blades extend generally axially of the hub. A spring is mounted on each of the blades and in the hub, the spring biasing the blades toward the first position, but of sufficient flexibility to permit the blades to move to the second position upon launch of the vehicle from an underwater launch tube.

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

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

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

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

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

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

Abstract: An autogyro aircraft has freewheeling rotor blades that provide lift. A separate pusher propeller provides forward thrust. The rotor system (20) has a collective arm (30) as a control for selectively setting and maintaining a tension force on a collective cable to regulate the rotor blade angle of attack or pitch angle between a no-lift attitude and a positive lift angle. The collective arm (30) sets a tension on collective cable against a coil spring biasing. The collective arm is connected to pivot or tilt a pitch change horn assembly and, in turn, connected rotor blades. The collective arm can be selectively set and maintained and released and reset both on the ground and in flight.

Abstract: A variable-pitch multi-blade rotor for use as the anti-torque rear rotor of a rotating wing aircraft has a rotor with a central shaft rotated about a central axis, a hub constrained to rotate with the central shaft about the central axis, blades distributed around the central axis with each blade being connected to the central shaft by a twistable element, a pitch control disk for the blades which is constrained to rotate with the central shaft but free to slide axially relative to the central shaft, and a member for controlling the sliding of the pitch control disk along the central shaft. Each blade root is secured to a transverse thrust and pitch control lever forming a yoke having one end hinged to the hub and another end hinged to the pitch control disk.

Abstract: The invention relates to a regulating device for maintaining constant the rotary speed in turbines of the type comprising a turbine hub and a number of turbine blades which are axially, but rotatably connected to the hub and have such a shape and are so aranged that each turbine blade in a flowing medium and by the action thereof is acted on by a torque about its longitudinal axis against the action of a spring device and acts on the turbine hub by a torque acting about the axis of rotation of the turbine.

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

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

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: A controllable lifting rotary wing for an aircraft wherein each rotor blade is mounted in such a manner that it has freedom to oscillate in pitch about its feathering axis. The aerodynamic center on each rotor blade is displaced forward of this feathering axis over at least a portion of the span. Cyclic aerodynamic forces on this spanwise portion cause the blade to change pitch sinusoidally once-per-revolution of the rotor whenever the rotary wing aircraft experiences a change in flight attitude or velocity. The result is that the rotor blades automatically and continuously change pitch to cancel out cyclic lateral flapping moments which are normally produced on a helicopter rotor blade by such a flight disturbance. This rotary wing has greatly improved stability by virtue of this self-feathering action. Cyclic pitch control moments are applied to the rotor blades by indirect means which do not interfere with automatic blade feathering. Means for control of collective pitch of the blades are also provided.

Abstract: A helicopter rotor with foldable blades has, in the hub and blade roots, holes for mounting the blade roots to the rotor hub with connecting bolts passing through these holes in the operating position of the blades. Additionally, at least one blade of two blades and the hub have aligned holes for holding the respective foldable blade in a folded position, whereby one of the regular connecting bolts passes through the aligned holes, which are located as close as possible to the pivoting point connecting a pitch angle control rod to a pitch angle control sleeve.

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 main helicopter rotor on which a rotary tubular shaft supports, at its top end, an annular hub integral with the tubular shaft itself. The assembly consisting of the tubular shaft and the hub is closed off at the top by a bell connected in removable manner to the hub and enclosing an oscillating plate assembly supported on a fixed shaft extending inside the aforementioned tubular shaft. A rotary ring on the oscillating plate assembly is connected to blade pitch change levers via respective rocker arms connected in articulated manner to the aforementioned rotary ring via respective pins extending radially in relation to the aforementioned bell and accessible via respective radial holes formed through the same.

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 universal joint for use in a pitch cone rotor system in a helicopter is comprised of crossed lift beams, one beam of which is coupled to the rotor hub and the other beam of which is coupled to the driven rotor shaft. The two crossed lift beams are coupled to each other through a cruciform case. The cruciform case in turn is coupled to each of the crossed lift beams by means of a plurality of flexures. The flexures and cruciform case are made of composite fiber materials and the flexures are soft enough to permit angular and translational deflections of the crossbeams with respect to each other thereby tending to smooth out and reduce sudden changes in rotor speed between the shaft and rotor system and thereby tending to make rotor speeds more uniform. The crossed lift beams are further coupled together at the center of their crossing by a flexible elastomeric tension link which conducts rotor loads between the two beams when the rotor develops negative lift loads on the ground and in flight.

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 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: 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: The blade angle of the blades is adjustable in a rotor for a rotary wing craft by a lever mechanism (13, 14 or 41, 42) secured to the radially inner end of an extension bushing (7; 7.1) or shaft (43). The extension bushing (7; 7.1) or shaft (43) is connected with its radially outer lever (15 or 44) to the blade root (2) or a blade root mounting (39, 50) of a rotor blade in an angular position adjustable manner for adjusting the tracking of the blades. The bushing (7; 7.1) or shaft (43) is adjustable in its angular position relative to the blade root (2) by adjustment screws cooperating with a free end of the lever (15 or 44) which reaches into a gap between two of such adjustment screws (16 or 45) cooperating with counter nuts (17 or 46). By adjusting the angular position of the bushing or shaft with the screws it is possible to assure a uniform tracking among all the blades of a multiblade rotor. Such uniform tracking is desirable if the blades of a rotor are to rotate in the same 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 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 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: The blade angle of the blades is adjustable in a rotor for a rotary wing craft by a lever mechanism (13, 14 or 41, 42) secured to the radially inner end of an extension bushing (7; 7.1) or shaft (43). The extension bushing (7; 7.1) or shaft (43) is connected with its radially outer lever (15 or 44) to the blade root (2) or a blade root mounting (39, 50) of a rotor blade in an angular position adjustable manner for adjusting the tracking of the blades. The bushing (7; 7.1) or shaft (43) is adjustable in its angular position relative to the blade root (2) by adjustment screws cooperating with a free end of the lever (15 or 44) which reaches into a gap between two of such adjustment screws (16 or 45) cooperating with counter nuts (17 or 46). By adjusting the angular position of the bushing or shaft with the screws it is possible to assure a uniform tracking among all the blades of a multiblade rotor. Such uniform tracking is desirable if the blades of a rotor are to rotate in the same plane.

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: 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: A rotatable bladed device for vehicles, such as especially a helicopter rotor, which has its blade pitch controlled by a setup which includes a swash plate setup controlled by a set of hydraulic actuators and the particular swash plate setup position and attitude in turn controls the blade pitch by a plurality of rods pivoted together at one end at one particular point movable longitudinally of the rotor axis, one of which rods has its other end pivoted at a point on the pitch arm by which it controls pitch and another of which rods is also pivoted at a point fixed by the rotational position at any particular time of the rotor hub.

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: A helicopter rotor system using composite flexbeams for connecting a rotor blade to the rotor hub, each flexbeam being of C-section and having a web section made up of 0.degree. and .+-.45.degree. plies and top and bottom flanges made up of low angle plies in the direction of their length with their ends being connected by an arc of plies so that the top and bottom flange plies are continuous with an attachment fitting encased at the ends of the flexbeams.

Abstract: A connecting element having end regions (22, 23) joined by an intermediate by an intermediate region (26) is constructed of a plurality of fibre filaments extending longitudinally and continuously throughout its length. The fibers in the end regions are embedded in a thermo-setting resin matrix material and the fibres in the intermediate region are embedded in a resilient matrix material thereby permitting relative resilient torsional movement of the end regions about a longitudinal axis. Such a connecting element is particularly suited for use in a helicopter rotor and several embodiments are described and illustrated. In all embodiments the torsional flexibility of intermediate region (26) provides for blade feathering movements and in a preferred embodiment the inner end region (22) is constructed so as to be resiliently flexible in a blade flap plane and the outer end region (23) is constructed so as to be equally resiliently flexible in the blade flap and lead/lag planes.

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: 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).