JPS6021119B2 - rotary wing of a rotorcraft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to rotorcraft rotor blades having a rigid hub to which the base of each blade is attached via layered spherical thrust bearings and drag resilient adjustment struts.

French Patent No. 73,253 published February 1, 1974
No. 1y' The fully rigid hub of the rotorcraft rotor blade described herein has as many radial tubular arms as vanes;
The base of each vane is connected to the interior of the corresponding tubular arm via a spherical thrust bearing also therein, and one end of the hydraulic or pneumatic drag damping device connects the corresponding vane within the tubular arm. and the other end to the exterior of the arm corresponding to the adjacent vane, respectively, by means of a ball and socket joint, for which purpose a large hole with an air-tight seal is provided in the bottom of the arm so that the 8th part of the damping device must go through the department.

This hub has many drawbacks. In other words, the radially arranged tubular arms are subject to bending and tensile stresses due to the centrifugal force acting on the blades, so the walls must be relatively thick, which increases the overall weight of the rotor blade. , due to the complex structure, high production costs (requiring complex molding and a lot of machining work, especially finishing), and the need to make a hole in the wall of each arm to pass through the body of the damping device. As the arm receives a large mechanical stress, its fatigue limit becomes considerably smaller, and when the rotor blade starts and stops, the damping device does not exert an elastic restoring force on the blade, so the blade becomes neutral with a drag angle of 0. Since the blades do not return to position and the drag-induced flapping of the blades is limited only by the abutment of the piston of the damping device against its cylinder head, the blades of this known rotor do not move very close to each other when starting or stopping the rotor. may occupy different positions, and this creates a large unbalance during these movements that excites the entire rotary-wing aircraft at the rotational frequency of the rotor, resulting in a phenomenon known under the name ``ground resonance.'' Resonance phenomena inherent in rotorcraft that are equipped with a rotorcraft may cause serious damage to the aircraft before takeoff or after landing. The fully rigid hub of a rotor wing of a rotary-wing aircraft, as described in French Patent Application No. 75 25 614, published March 19, 1976, also has as many radial arms as there are blades, each arm The inner cavity for introducing the U-shaped member is opened on both sides, and the branching part of this U-shaped part is formed integrally with the joint fixed to the base of the blade. The shaped members are connected to the arms of the hub by spherical thrust bearings also mounted in the bores of the arms, and the elastomeric drag damping devices are each connected at one end to a joint fixed to the base of the vane and at the other end. The hub is connected to the center of the hub by a ball joint that secures the hub to the rotor's mast.

This damping device is therefore complex, heavy and expensive, and because of its construction, the hub of this known rotor must have a very large thickness in all directions of the rotor's axis compared to the thickness of the individual blades. Therefore, the weight of this hub is necessarily increased by the weight of the U-shaped member and the joint integral therewith. This known hub is also very expensive to manufacture due to its complex structure. Second on July 16, 1971
French patent application No. 69,3541, published as No. 69,3541, published as No. 69,3541, describes an elastic coupling device for damping between a rotor blade of a rotorcraft and its rotor hub. There is.

This embodiment of the device includes an elastic member and a buffer member bonded to each other by interposing a layer of viscoelastic material with high rigidity and deformation recovery between at least a plurality of parallel metal plates. This coupling device, however, applies to rotor blades having haps with arms that connect the bases of the blades by a purely mechanical drag coupling. Although the rotor blade of the rotorcraft according to the present invention is of the type described above, it does not have any of the above-described defects of conventional rotor blades.

The rotor blades of the rotary-wing aircraft according to the present invention are constructed by alternately stacking metal plates and plates of elastic material with a large deformation recovery force, and each of the rotor blades serves as a frequency adjusting device. Both ends of the adjustment struts are connected via ball joints, one end to the base of the blade and the pond end to a portion of the hub, so that each strut is always slightly inclined with respect to the corresponding blade; It is characterized in that the center of one of the joints is close to the flapping axis of the vane passing through the center of the corresponding layered spherical thrust bearing. In the first embodiment of the rotor blade of the present invention, the circumferential edge of the annular plate-shaped hub has a convex polygonal shape or a substantially circular shape, and the same number of openings as the number of blades are provided in the circumferential direction of the rotor blade. A laminated spherical thrust bearing is installed between one outer green of this closure and the tip of the branch piece of the fork-shaped part integral with the base of the corresponding vane, and each drag force is The other end of the adjustment strut is located between a layered spherical thrust bearing connected to one blade and a layered spherical thrust bearing connected to a blade immediately before or after that blade in the rotational direction of the rotor blade. It is connected to one point on the periphery of the hub via a ball joint. The hub of the rotor blade of the invention has a peripheral green part in the form of an annular plate, into which the base of each vane passes through an opening in the said peripheral part of the hub and cooperates with a corresponding spherical thrust bearing in the form of a fork. Since this closure, which is connected via a member, extends in the axial direction of the rotor blade, the said circumferential edge in the form of an annular plate of the hub has a thickness in the said axial direction of the rotor blade compared to the thickness of each blade. Because it can be made very small and because it does not have radial tubular arms with large wall thicknesses, the rotor hub of the present invention is much lighter than similar rotor hubs known in the art.

Since the rotor hub of the present invention has a simple structure, manufacturing costs can be reduced. Since each blade of the rotor of the invention is connected by an elastic adjustment strut as described above, it returns to its neutral position corresponding to a zero drag angle by the action of a plate of elastic material. Therefore, when the rotary blade of the present invention starts and stops, all the blades assume a neutral position, which tends to promote the dangerous phenomenon of "resonance with the ground" mentioned above. To surely avoid occurrence of a large unbalance. Furthermore, since the elastic adjustment struts serve as modulators for the natural frequency of the drag force, their elasticity allows the natural principal frequency of the drag-induced vibrations of each blade to be lower than the frequency corresponding to the nominal rotational speed of the rotor. It can be adjusted to a value small enough to avoid any risk of resonance during normal rotation of the rotor, but this value must be large enough to facilitate eliminating problems caused by resonance with the ground. do.

In addition, due to the large deformation recovery force of the elastomer material that makes up the viscoelastic buffer section of the strut, the rotational speed of the rotor blade changes to the natural main frequency of the blade vibration due to drag, especially when the rotor blade starts and stops. When passing through the corresponding value, the movement of the vanes due to the drag force is greatly damped, so that the risk of the occurrence of resonance phenomena is completely eliminated. At the almost rigid center of the hub, the same number of openings as the number of blades are provided in the direction of the rotor blade, and the outer edge of each opening and the corresponding branched piece of a fork-like member integral with the base of the blade are installed. Rotary wing aircraft rotors having spherical thrust bearings mounted between the tips are also known.

However, the hub of this known rotor has a connecting arm associated with each blade and a star-shaped outer edge that is flat in the star-shaped plane and maneuverable in a plane perpendicular to this plane. There is. Such a star-shaped hub has a much larger diameter than a hub with a convex polygonal or circular periphery of the rotor according to the invention, and this known rotor has a much larger diameter than the rotor according to the invention, other things being the same. Due to the greater drag generated, the rotor blade of the present invention exhibits very good energy efficiency. A helicopter equipped with the rotary wing of the present invention has the same fuel consumption as a light rotorcraft with a weight of about 2 to 4 metric tons, and a heavy rotorcraft with a weight of about 8 metric tons. A speed increase of about 5% can be achieved. On the other hand, the flexible arms of known rotor blades have great flexibility, which causes difficulties in starting and stopping the rotor due to strong winds. The very small diameter of the hub of the rotor of the present invention allows the base of the blade to be anchored at a short distance from the rotor's center of the rotor, thereby reducing drag on the rotor and thus Streamlining becomes easier. Because the rotor hub of the present invention has a small diameter and no arms, it can weigh much less than a star-shaped hub with comparable characteristics. Furthermore, the rotor hub of the present invention is much simpler to manufacture than a star-shaped hub, and therefore the manufacturing cost is much lower. Finally, since there is no flexible arm, the flapping ratio of the blades is extremely small, and the drive output of the rotor is much lower than that of a star-shaped rotor, other things being the same. As a result, the rotor of the present invention has a significantly lower level of vibrational excitation. In a preferred embodiment of the rotor according to the invention, the fork-like member connecting the base of each blade to the corresponding spherical thrust bearing is an extension of the base of the blade, and the tips of the branches are e.g. It is fixed to the support member of the spherical thrust bearing with bolts.

This embodiment is particularly advantageous in that the number of components of the rotor blade can be reduced and the base of each blade can be brought as close as possible to the axis of the rotor blade. In a further embodiment of the rotor according to the invention, the fork-like element is essentially constituted by a radially arranged yoke, the tip of which is remote from the hap, for example in the plane of the rotor. The yoke is fixed to the base of the corresponding blade by two pins that are almost orthogonal to each other, and the ends of the yoke do not contact the peripheral green part of the hub, but have a rigid rigid structure placed on both sides of the hub. The spherical thrust bearing is made up of two members and is fixed to the support section of the corresponding spherical thrust bearing by, for example, two bolts.

For example, the yoke can basically be composed of two rigid plates that are integral with each other, parallel to each other, and substantially parallel to the peripheral edge of the rotor blade in the form of an annular plate. can. This latter embodiment is advantageous in that it is particularly suitable for the construction of rotor blades with foldable blades; in fact for this purpose one of the pins fixing the yoke to the base of the blade must be It is only necessary to allow the book to be removed and the blades to be folded in the plane of the rotor by pivoting about the other fixing pin of the yoke. Since this yoke, in particular its two parallel rigid plates, can always have a considerably shortened radial length, this embodiment also exhibits substantially the same effect as the previous embodiment. Various types of helicopter tail rotors are already known.

Those constructed by mechanical linkages with ball bearings, roller bearings or needle bearings, and the openness imparted to blade fastening devices to enable flapping and pitching movements of the blades. It is known what was used. This latter type of tail rotor is described in French Patent No. 2,315,432, filed June 22, 1973. This tail rotor is a four-blade type, but the thin plates are arranged at right angles to each other and held at their center between two plates that are integral with the rotor's axle and form its hub. Two vertically flexible vertical members with a shape, each surrounding half of one of these vertically suitable members, and a side surface that is connected to the vertical member so as to form four blades. It has four shells with a specific shape. However, although this vertical material is composed of strong fibers coated with a thermosetting synthetic resin, it is particularly sensitive to bending motion corresponding to the flapping of the blades and torsion corresponding to the manipulation of the pitch of the blades. Their lifespan is limited because they are subjected to extremely large stresses depending on the combination. Furthermore, adjusting the pitch of the blades by refraction of the vertical material requires a large amount of operating force, so an automatic control device, especially a dual control device, must be installed for safety reasons. Furthermore, even if only one blade is damaged, especially the corresponding part of the vertical blade, the entire vertical blade, and therefore the two blades, must be replaced. Finally, in a structure in which the vertical material is passed through the center of the hap, it is not very desirable to provide an orifice for passing the center axis through the center of the vertical material, which is subjected to large stress, so it is customary to This makes it difficult to implement the pitch adjustment device, and furthermore, in this case, it is necessary to take great care when manufacturing this part of the hub, as disclosed in Patent Nos. 2 and 3.
This is pointed out in No. 15,432. The helicopter tail rotor according to the invention does not have any of the above-mentioned deficiencies.

The vanes, which are each connected to the haps via layered spherical thrust bearings with three degrees of freedom, are not subjected to excessive stresses that would shorten their lifespan due to the operating forces.

The force required to be applied to each vane to control its pitch variation is very small since it only needs to overcome the internal resistance of the corresponding spherical thrust bearing. When one of the blades of the rotor of the present invention is damaged, only that blade can be replaced without requiring the other blades to be replaced at the same time. In addition, the center of the hub of the tail rotor of the present invention can be made hollow to freely pass the pitch variation control device, so that the rotor of the present invention has a simple structure, compactness, and light weight. A single streamlined structure can be accommodated to reduce drag on the rotor as well as the upper hub itself. In addition to these advantages,
The helicopter tail rotor according to the invention requires virtually no maintenance other than replacing the laminar spherical thrust bearing and the drag adjustment strut after long-term use. Other embodiments of rotorcraft rotor blades according to the invention have hubs of different construction that are simpler, more mechanically strong, more compact, and have less aerodynamic drag. This rotor blade consists of a central body whose hub is an extension of the mast and has an upper plate and a lower plate, and one of the rigid parts of the layered spherical thrust bearing is connected between the two tips of the central body. The base of each vane is radially arranged and connected to other rigid members of the spherical thrust bearing by hollow yokes that allow the spherical thrust bearing to pass freely. and a first end and a second end of each drag adjustment strut are connected to a yoke, the first end of which is connected to a corresponding vane via a ball joint, respectively;
The second end is also characterized in that it is connected to a suitable location on the central body of the hub. The upper and lower plates of the hub of this rotor blade are not hollow in order to allow the spherical thrust bearing to pass through them freely, and the rigid member of the spherical thrust bearing is inserted between the tips of each. The two plates of this hub are resistant to the action of the centrifugal force on each vane as well as to the transverse tensile stresses and to the means connecting the vanes to the hub during rotation of the vanes. It also exhibits excellent mechanical strength against static and dynamic bending moments due to flapping and drag forces.

In this embodiment, the upper and lower plates of the hub are desirably thin, and reinforcing ribs are provided, for example, radially on the lower surface of the lower slope.

Therefore, the weight of the huff can be reduced without affecting its mechanical strength, and therefore its cost can be reduced. The main rotor of the helicopter, which is partially schematically shown in FIGS. 1 to 3, is of the four-blade type.

It has a unitary hub 1 constructed as follows. That is, the center part la forms a rotationally symmetrical body with the rotor's ball A as the center, and the center part la of this hapū
is connected to the upper part of the tubular mast 2 of the rotor blade by a frustoconical part lb, and together with this upper part constitutes a single metal member, for example made of forged material (in particular made of steel or titanium), in order to reduce the weight. There is. The circumference is almost circular (first
As you can see from the part lf in the figure), the circumferential twill part lc of Hap 1
The hub is formed integrally with the central part la and therefore with the mast 2 of the rotor blade, and the peripheral green part lc of this annular plate-shaped hub has the same number of blades as the rotor blade, that is, in this example, Four openings □ld are provided along the direction of the koji A of the rotor blade. Each of these openings □ld can have a planar shape, for example, as shown in FIG. It extends and reaches a short distance d inside from the substantially circular periphery lf of the surrounding green portion lc. Due to the structure described below, the assembly formed by the rotor's mast 2, the center circle part la and the peripheral green part lc of the hub is much lighter in weight than, for example, a conventional hub, which is generally made of metal and is rigid as a whole. It also shows high mechanical strength, especially against tension and stress caused by centrifugal force on the surrounding green part lc. A layered spherical thrust bearing 3 of a known shape is attached to the outer line le of each open row b of the peripheral green part 'c of the hub.

In this embodiment, this layered thrust bearing 3, whose geometrical center is indicated by C, has a convex blastomere-shaped core body 3a made of metal, for example, an aluminum alloy or a titanium alloy.
This core body 3a has a closed opening ld and a circular green lf (Fig. 1).
It has two ear-like protrusions that are respectively engaged with the upper and lower surfaces of the peripheral edge lc between the two. This core body 3a is fixed to the circumference lc of the hub 1 by its ear-like protruding pieces, bolts 4, and nuts (see FIG. 3). The layered spherical thrust bearing 3 also has a rigid support member 3a made of the same metal as the core body 3a and having a concave spherical inner surface. The cross-sectional shape of the support member 3c in the radial direction of the hub is as shown in FIG. Convex spherical surface of core body 3a and support member 3c
A laminated portion 3b is provided between the concave spherical surfaces of the core body 3a and the supporting member 3b, in which rigid metal blastosphere pieces made of the same circle-shaped sphere pieces and layers of elastomer are alternately stacked. Part 3
c, the metal blastomere piece, and the single layer of elastomer are assembled together by vulcanization to form an integral body that transmits compression in all axial directions, but elastic deformation occurs due to shearing of the elastomer layer in the laminated portion 3b, and the core This allows relative rotational movement between the body 3a and the support member 3c. Cylindrical holes 3f and 3g are provided in the core body 3a and the support member 3c, respectively, in the direction of the laminated portion 3b.
A conical hole 3e is provided which matches the . This hole 3
E, 3f, and 3g are used to facilitate injecting the elastomer between the metal blastomere pieces by die casting during vulcanization. Each of the four blades 5 of the rotor shown in FIGS. 1 to 3 may have a suitable internal structure, for example a synthetic resin covered with a woven layer impregnated with a synthetic resin. Alternatively, it can be constructed by coating mineral fibers with a thermosetting synthetic resin and sintering them using a known technique. Although the invention is not limited to such vane embodiments, the support member 3c of each spherical thrust bearing 3 is formed by branching pieces 5a and 5b of fork-like members fixed to the base of the corresponding vane 5. It is attached between the tips of the
In the embodiment shown in the figure, the fork-like member is an extension 5a-5b of the base of the blade 5, and the tips of the branch pieces 5 and 5b are connected to the upper end and T end of the support member 3c of the spherical thrust bearing 3. Each is fixed. This fixation is achieved in particular by a washer fitted into a hole provided in alignment with the tips of the two branch pieces 5a and 5b at the base of the blade 5, and two bolts 6a inserted into a hole in the support member 3c of the spherical thrust bearing 3. 6b
This bolt is then tightened with a nut 6c (see Fig. 3). In the present invention, each blade 5 is connected to a support 7 (FIG. 1) for elastically adjusting the drag force, and as can be seen from FIG.
7c and plates 7d and 7e made of an elastic material with a large resilience against deformation are alternately stacked to form a metal plate 7a.
~7c assembled by vulcanization or adhesive.

One end of each support column 7 is directly connected to the base of the blade 5 by a metal fitting 8 and a ball joint 9 attached to the tip of an extension of the central metal plate 7b. The other end of each support column 7 is formed by an extension of both outer metal plates 7a and 7c, and is fixed to a short yoke 11 by bolts 10a and 10b. It is connected by a ball joint 12 to a mounting piece 13 fixed to a part of the peripheral edge of the peripheral green part lc of the mounting piece 1.
3 is a spherical thrust bearing 3 attached to the blade 5;
and a spherical thrust bearing (not shown in FIG. 1) attached to another blade immediately before the rotor in the direction of rotation of the rotor blade (arrow f in FIG. 1). In this embodiment, the support 7 is attached to the periphery of the hub by bolts 14.
The fixed point of the inner end of the blade 5 is the neutral position of the blade 5 and the other blade immediately preceding it in the rotational direction f, that is, the position occupied by the longitudinal axes of these blades when the rotor is stopped (drag angle 6 =
0), two mutually orthogonal radial axes R
, and is located on the bisector B after R2. However, it is not an essential requirement that the fixation points at the inner ends of each strut 7 be positioned accurately in this way. On the other hand, 1 of the present invention
One feature is that in this preferred embodiment, the center of the ball joint 12 connecting each strut 7 to the hub 1 is located at the center C of the spherical thrust bearing 3, as is clear from FIG.
is close to the flapping axis D of the blade 5 passing through the
In the main rotor blade of this example, this flapping axis D is, of course, approximately horizontal. Further, the fork-like member 5 of the blade 5
A pitch adjustment lever 15 is fixed to a-5b on the opposite side from the support 7 attached to the blade 5.

In the embodiment shown in FIGS. 1 to 3, this pitch adjustment lever 15 has two holes 15a (FIG. 3) into which the tips of the bolts 6a and 6b are fitted, and nuts 6
c, move the lever 15 to the lower branch piece 5 at the base of the blade 5.
There are stripes on the tip of b. Further, as another feature of the present invention, the adjustment end 15b of the pitch adjustment lever 15 of each blade 5 is arranged in the same manner as in the case of the ball joint 12, but opposite to the ball joint 12 with respect to the center C of the spherical thrust bearing 3. On the side,
It is close to the flappy sawg axis D of the blade 5. At the end of the branch piece 5b on the lower side of the fork-shaped base of each blade 5, close to the rotor, there is a reciprocating ring 17 attached in a known manner around the mast 2 of the rotor on the underside of the hub 1.
A stopper 6 is provided for controlling the downward flapping of the blades 5 in cooperation with (FIG. 3).

In the embodiment shown in FIGS. 1 to 3, the metal stopper 16 has an angled shape, and one flange thereof is provided with a hole for passing the lower ends of the bolts 6a and 6b. The nut 6c can be tightened between the tip of the lower branch piece 5b and the tip of the pitch adjustment lever 15. The reciprocating ring 17 is also made of metal,
It is mounted slidably in the radial direction with light friction within an annular slit 18 of a mounting piece 19 fixed around the mast 2 of the rotor. The attachment piece 19 forming this annular slit 18 having an appropriate depth in the radial direction may be a single piece, or a plurality of attachment pieces 19 may be used.
may be provided at equal intervals around the mast 2. 1 to 3 do not show any machinery for adjusting the respective pitch variations of each vane 5, either simultaneously or separately.

Indeed, the invention is not limited to a particular embodiment of such a machine, of which a number of embodiments are already known. In such a machine, it is sufficient that the ring rod applies a force substantially perpendicular to the upward or downward direction to the adjusting end 15b of the pitch adjusting lever 15, depending on the direction in which the pitch needs to be changed. When the rotor is stopped, the stopper 16 cooperates with a reciprocating ring 17 slidably mounted in the radial direction to prevent the four blades from simultaneously rotating downward. In this static state,
The longitudinal axis of each vane 5 lies in the same vertical plane as the radial axis, eg R, so that the vane is in a neutral position (6=0). When the rotor blade is rotated by the mast 2, the spherical thrust bearing 3 receives a resultant force in the radial direction along the radial direction due to the centrifugal force applied to each part of each blade 5.
It is absorbed by the compression of the laminated portion 3b, which has an elasticity of .

On the other hand, due to the action of various aerodynamic and inertial moments and forces acting on each blade, the blade is brought into an equilibrium state by shear deformation around the center C of the elastic laminated portion 3b. The driving torque is transmitted to each vane by the strut 7 by compressing the strut 7, so that each vane 5 takes a "lag" position and all vanes are connected between the rut R, whose longitudinal axis L indicates the neutral position of the vane. The drag angle 6 is almost the same for both. During normal operation of the rotor and when the helicopter is in translational flight, the variation of the drag force on each blade 5 (this is just a fraction of the angle between the angle L and the axis R, relative to the value of the angle 8 defined above) (expressed as a fluctuation) is reduced to a large extent by the action of plates 7d and 7e (FIG. 2) made of a viscoelastic material with a large deformation recovery force and forming the support column 7.

In addition, the ball joint 12 attached to the inner end of the support column 7 is connected to the blade 5.
Because of its proximity to the flapping axis D of the blades, the flapping movement of the vanes about this axis D imposes only negligibly small compressive or tensile stresses on the struts 7, and the struts 7 It exerts only a slight elastic return and damping effect on the flapping movement of the blades 5.
Adjuster 15 of pitch adjustment lever 15 connected to each blade 5
The same is true for the nearly vertical movement of b for the same reasons. When the rotor stops, the strut 7 connected to each blade 5 recovers its length and shape and exerts a return force against the base of the blade 5, which causes the blade 5 to return to the neutral position (8=0). The downward deflection of the blade is again constrained by the reciprocating ring 17.

The four-blade rotor blade according to the present invention shown in FIGS. 4 and 5 is also the main rotor blade of a helicopter, and the blades are foldable for storing the helicopter.

In Figures 4 and 5, for the same type of parts,
The same numbers as in the case of FIG.

Regarding the villages of the embodiment illustrated in FIGS. 4 and 5,
We will limit ourselves to pointing out the differences from the embodiments illustrated in FIGS. 1 to 3 and described above. As in the previous embodiment, each spherical thrust bearing 3 is located between one outer green le of the open load d extending in the direction of the rotor axis A on the one hand and the circumferential green lc of the hub, and on the other hand. In the above, the fork-like member 20a-20b is attached between the branch pieces 20a and 20b of the fork-like member fixed to the base of the blade 5, but the fork-like member 20a-20b is attached to the fourth
In the figures and FIG. 5, it basically consists of two rigid plates 20a and 20b that are substantially parallel to each other and substantially parallel to the twilling portion lc between the annular plate-shaped rotor blades. As is clear from FIG. 5, these two plates 20a and 20b are placed on both sides of the peripheral green part lc of the hub without contacting it, and are connected to the spherical thrust bearing by two bolts 6a and 6b. It is fixed to the support member 3c of No.3.

Further, the ends of these two parallel plates 20a and 20b are fixed to the base of the blade 5 by two pins 21a and 21b, and at least one of these two pins, for example 21a
are removable, for example, tubular pins that fit with light friction into holes aligned with the outer ends of the two plates 20a, 20b and the base of the blade 5. This tubular pin 21a is normally held immovable in the hole by, for example, a wire clamp 22, but if the wire clamp 22 is removed, the tubular pin 21a can be extracted, and after this extraction, the blade 5 By rotating the blade 5 in the direction of arrow F (FIG. 4) about the immovable pin 21b, the blade 5 can be folded and stored behind the helicopter in the stored state. Of course, this can only be done after removing the support 7 of the blade 5 at the metal fitting 8. Any modifications may be made to the embodiment of the helicopter main rotor described above, all of which are within the scope of the present invention.

The hub of the rotor blade of the present invention is constructed as a single metal member together with the mast 2 of the rotor blade, and a layer of woven fabric made of synthetic fiber or mineral fiber with high mechanical strength is coated with thermosetting synthetic resin. By compacting and stacking them, a composite structure can be constructed using known methods. in this case,
For example, woven fabrics made of glass fibers or synthetic fibers known under the trade name KEVLAR can be used.
It is also possible to use a woven fabric made of carbon fibers, which has greater strength and a significantly lower density, which is advantageous for further reducing the weight of the hub of the rotor of the present invention. Although composite structures of this type have been used in the past for making semi-rigid or partially flexible rotor hubs, they are very useful for constructing the rotor hub of the present invention. It is also possible to produce composite structures of this type with high rigidity. Of course, the hub of this type of composite structure must be secured by suitable means, such as bolts, to the upper end of the mast of the rotor, which generally consists of a hollow metal shaft. Similarly, in the case of a rotor with foldable blades as shown in FIGS. 4 and 5, two plates 20
a, 20b can be made of metal, or the hub 1
It is also possible to have a composite structure as described above.
The two plates 20a, 20b which serve to connect the base of each vane 5 to the spherical thrust bearing 3 can also be replaced by fork-like elements of other shapes, in particular by radially arranged yokes. Its end remote from the hub is fixed to the base of the vane by two pins approximately perpendicular to the plane of the rotor, one of which is removable and the other It is desirable to be able to fold the blade by rotating it around a fixing pin.
On the other hand, the pond end of the yoke has two flat rigid members that are not in contact with the periphery of the hub and are not placed on either side of it, but are placed on both sides of it, and are connected to the spherical thrust bearing by, for example, two bolts. It is fixed to the support village. As mentioned above, the circumferential green part lc of the hub 1 of the rotor blade of the present invention has the shape of an annular plate, and the circumferential green part lf can be approximately circular as shown in FIG. 4), or a convex polygon, preferably a regular polygon, as shown in FIG. The hub is clearly distinguished from the hub having the star shape, that is, the concave polygonal circumference mentioned in the description of the prior art. A helicopter tail rotor according to the invention is shown in FIGS. 6 and 7, except as follows:
This is the same as the above-mentioned main rotor blade shown in FIGS.

That is, the core body 3a of each spherical thrust bearing 3 is fixed to the peripheral green portion lc of the hub by a single radial bolt 4. A tubular part 23 having an outer diameter smaller than the wall diameter of the tubular mast 2 is fixed to the hollow center part la of the hub 1 with a bolt 24. A tube 25 having a longer length and a smaller diameter is slidably attached, for example, by a vertical groove, and a pitch adjustment shaft 26 that does not rotate is attached along the center of the tube 25 and is located in front of the blade 5. The front ends of the tube 25 and the pitch adjustment shaft 26 are connected to each other by a ball bearing 27. Around the front end of the tube 25,
A star-shaped member 29, which has a technical term meaning "spider bead", is fixed by a bolt 28.
This star-shaped part 29 has the same number of arms 29a as the blades 5, and the tip of each arm 29a is connected to a ball joint 30 and a link rod 31 to a fork-like member 5a-5b forming an extension of the base of the blade 5. and a metal fitting 32. This transmission system is secured to the fork-like members 5a-5M by the same bolts 33 that secure the fastening fittings 8 of the struts 7 on the opposite side of the vanes 5 (see FIG. 6). This bolt 33 passes through a wedge-shaped member 34 made of, for example, a thermosetting synthetic resin filled with glass fiber, and the metal fittings 8 and 32 are supported on the triangular surface of this wedge-shaped member 34. . In the present invention, in particular, two of the fork-like members at the base of the blade 5 shown in FIG.
Stops 16a and 16b are provided at the ends of the two branches 5a and 5b close to the mast 2, which cooperate with fixed stops 17a and 17b, respectively, to prevent the blades 5 on either side of the substantially vertical plane of the tail rotor. control flapping.

One fixed stopper 17a has a pitch variation adjustment device 29.
On the extension line of the mast 2 in the direction of the tubular part village 2
3, and the other fixed stopper 7b is integral with the mast 2 and is formed from the outer wall surface of the mast 2 as an annular projection or as a plurality of radial projections arranged opposite to the base of each blade. It is formed to protrude. As in the case of the main rotor, the spherical thrust bearing 3 of the tail rotor allows a limited range of drag movement of the blades 5, together with the damping and elastic adjustment effects of the struts 7, and the stops 16a and 16b. Stoppers 17a and 17b
In cooperation with the tail rotor, a limited range of flapping movement is possible on either side of the approximately vertical plane of the tail rotor.

By automatically controlling the pitch variation of the tail rotor, the pitch adjustment shaft 26 is moved in the direction of the mast 2 and the tubular member 23.
The star-shaped member 29 can be moved by the ball bearing 27 via the blade 5 and each member 32, 31, 30 by sliding it in either direction along the common center line of the tube 25. The shaped member 29 is moved as indicated by the double arrow line G.
Each member 32, 31, 30 converts each sliding movement of the star-shaped member 29 in either direction of the double arrow line G into a rotational movement about the longitudinal force L of the blade 5. This rotation is possible within a limited range due to the deformation of the elastic laminated portion 3b of the spherical thrust bearing 3 about the radial axis passing through its center C, and this elastic laminated portion 3b The far D exerts only a slight restoration on the blade 5 and is added to it.
Absorbs the resultant force. The helicopter tail rotor according to the invention has the following advantages:

That is, the mechanical moment of flapping and drag applied to each blade 5 is much smaller, which reduces the alternating stress to which the blade is subjected and can considerably extend its life. If one blade is damaged, it can be replaced individually, which is not possible in the case of conventional tail rotors, which have a support piece that extends from the tip of one blade to the tip of the opposite blade. be. The struts 7 connected to each vane 5 can be fixed to the base of the vane by the same means as the fittings 32 that attach the pitch variation adjustment device 29-30-31 to the base of the vane, in particular by bolts 33. . As is clear from FIG. 6, the fixing points 14 of each support column 7 to the peripheral green portion lc of the hub 1
and the adjustment end of the metal fitting 32 is located at the center C of the spherical thrust bearing 3.
It is close to the flapping axis D of the blade 5 passing through. Moreover, compared to the previously known tail rotor in which each pair of blades is supported by a single support piece, the hub of the tail rotor according to the invention with a hollow center part la has a hollow central part of the hub 1. Tubular mast 2 and tubular member 23 fitted into la
It is easy to assemble by using the large cylindrical hollow part of the 25-26-29 pitch variation adjustment device.
The size and weight of can be reduced. Such a construction also facilitates a single streamlined attachment of the hub and star member 29 to reduce drag in the tail rotor of the present invention. In addition, the tail rotor of the present invention reduces mass and manufacturing costs, and in terms of maintenance, the spherical thrust bearing and the strut for elastic adjustment of drag can be replaced for long-term use of more than 2,000 hours on average. It has a remarkable feature in that it only requires The force required to control the pitch variation of each blade of the rotor according to the present invention is relatively small due to the small restoring force provided by the spherical thrust bearing. Heavy automatic control is not required, and single automatic control is sufficient, which is economically advantageous. In fact, even if this single automatic control fails, the control force required to continue the flight is small, so the pilot can control the pitch of the tail rotor without having to exert excessive effort. Some of the modified embodiments described above regarding the main rotor of the present invention are also applicable to the tail rotor of the present invention.

The main rotor of the helicopter, partially schematically shown in FIGS. 8 to 10, is of the four-blade type. It has a rigid hub 1 constructed as follows. The center portion la is formed by a tubular column having a diameter close to zero of the diameter of the mast 2. The center part la is integral with the upper plate 1g, and the upper part 2a of the mast 2 is integrated with the lower plate lh, and the inner circumference of the lower plate lh has an annular flange formed on the outside of the lower part of the center part la. li is fixed by a bolt 40, for example. As is clear from Fig. 9, the lower plate 1h' has an almost star-shaped shape with four arms, and the same is true for the upper plate 1g, with both arms having the same dimensions as each other. They are arranged so that they overlap exactly one above the other. As is clear from FIG. 8, the upper plate 1g and the lower plate lh each have a small wall thickness that is approximately equal to the wall thickness of the center portion la, and a reinforced portion 19 with a large thickness is provided at the tip of the arm. 1h, and two pairs of holes 41 are provided in this reinforcing portion, substantially vertically aligned. For example, the arms of the upper plate 1g and the lower slope lh are arranged such that the inguinal lines of the two pairs of holes 41 are approximately parallel to the inguinal lines A of the hap 1 and the mast 2, and are spaced at a certain distance from the bag center line A, for example, at the center. The dimensions are determined so that the radius is 3 to 4 times the radius of la. As is clear from FIG. 8, the lower surface of the lower plate 1h' is reinforced by radial ribs li. Mast 2 and lower plate! h, the tubular central portion la, and the upper plate 1g may each be constructed as a single metal member, for example, by casting, or may be constructed of woven synthetic fibers or mineral fibers with high mechanical strength, as described above. It is also possible to construct a composite structure consisting essentially of layers of fabric coated with thermosetting resin and stacked together. Between the tips of each pair of arms on the upper plate 1g and the lower slope lh, there is a layered spherical thrust bearing 3 of a known shape.
is installed.

In this embodiment, this layered thrust bearing 3, whose geometrical center is indicated by C, has a truncated metal core 3a with a convex surface made of, for example, an aluminum alloy or a titanium alloy. It is integrated with a support member consisting of an upper part 3a and a lower part 3a2 that can be fitted between the tips of the arms of the plate 1g and the lower plate lh. This support member has two holes aligned with the two pairs of holes 41 at the tips of the arms of the upper plate 1g and the lower plate lh, and bolts 4 are inserted into these holes and inserted through the core body 3a. This allows the spherical thrust bearing 3 to be directly fixed to the green ends of the upper plate 1g and lower plate lh of the hub 1. The layered spherical thrust bearing 3 further has a support member 3c made of metal and having the same rigidity as the core body 3a and its support member, and the inner surface thereof has a concave blastomere shape. Between the convex spherical surface of the core body 3a and the concave spherical surface of the support member 3c, there is a laminated portion in which rigid metal blastomere pieces in the shape of several concentric spheres and elastomer layers are stacked alternately. 3b is provided, and the assembly of the core body 3a, the support member 3c, the metal blastomere piece, and the elastomer layer 3b is assembled by vulcanization or other joining methods as described above. In the present invention, the base of each of the four blades 5 of the rotor blade shown in FIGS. 8 and 9 is arranged in the radial direction of the rotor blade so that the spherical thrust bearing 3 can freely pass therethrough. It is connected to the support member 3c of the spherical thrust bearing 3 by a hollow yoke.

In this embodiment, the yoke, whose developed view is shown in FIG. and 42b, and a spacer 44 fixed between these two plates 42a and 42b by, for example, three bolts 45, and these three bolts are aligned with the upper plate 42a, the spacer 44, and the lower slope 42b, respectively. It passes through holes 46a, 46, and 46b provided in the same manner. As is clear from Figures 8 to 10,
The spacer 44 has a notch 43 in two plates 42a and 42b.
a, 43b and the ends of the two plates away from the hub 1, and the ends of the two plates have a pair of holes 47a, 47b. formed in alignment. In particular, as shown in FIG. 8, the base of the blade 5 is fitted between the ends of the two plates 42a342b on the side away from the hub a, leaving a slight gap between them.
The three members, that is, the upper plate 42a, the blade 5, and the lower slope 42b, are fixed to each other by two fixing pins 21A and 21B. These two fixing pins 21A and 218 are attached to the washer 48 in a direction substantially perpendicular to the plane of the rotor.
It passes through two pairs of holes 47a, 47b in the two plates 42a, 42b with holes 42a, 48b and the corresponding hole in the base of the blade 5. At least one of the two fixing pins, for example 21A, is removable as described above, so that the blade 5 can be rotated about the other non-removable fixing pin 21B, so that the blade 5 can be rotated in the plane of the rotor. It is desirable to be able to fold it. As is particularly clear from FIG. 8, the ends 42a, 42b of the plates 42a, 42b closer to the hub river are partially fitted into the grooves of the support village 3c of the spherical thrust bearing 3. its end 4
2a, 420 are fixed by a plate 49 which is fixed to the support member 3c with screws 49a between the grooves. In this embodiment, two plates 42a of the yoke
, 42b has an elbow-shaped protrusion 44a that protrudes from the yoke in the direction of the leading edge of the blade 5 (i.e., in the direction of rotation of the rotor shown by arrow f in FIG. 9). As is particularly clear from FIGS. 9 and 10, this elbow-shaped protrusion 44a is provided with a lumen 44b that opens toward the hub 1, and its two side walls is a ball D passing through the center C of the spherical thrust bearing 3.
Holes 44b aligned with the holes 44b. and 44& have been established.

In addition, it is desirable that the ball D is located within the plane of the center of the bolt 4 that fixes the spherical thrust bearing 3 to the upper plate 1g and lower plate Ih' of the hub. In front of this inner cavity 44b, a yoke 44c is provided on the ergonomic projection 44a of the spacer 44, and one arm of the yoke 44c has a hole 44c aligned with a rut E substantially perpendicular to the axis ○, and a yoke 44c.
4c2 is set. In the present invention, a strut 7 for resilient adjustment of drag, preferably constructed as described above, is connected to each blade 5 of the rotor as described below.

That is, the end (first end) of the support column 7 that is remote from the hub 1 passes through the bore 44b of the elbow-shaped protrusion 44a and the holes 440 and 44b2 in the side wall thereof, and fits both ends into this hole. It is connected by a ball joint 9 to a pin 49 which is fixed by suitable means. The end (second end) of the strut 7 closer to the hub is connected to the tubular member la of the hub by a ball joint 12, which is connected to the annular portion 51 of the tubular member la of the hub by a bolt. As is clear from FIG. 8, the inner wall of the tubular portion la is thicker in this annular portion. In this embodiment, the ball joint 12 connecting the second section of the strut 7 connected to one blade 5 is located immediately before the blade in the rotational direction of the rotor blade (arrow f in FIG. 9). It is fixed to the tubular member of the hub at the same level as the yoke connected to the vane and in the space between the yoke and the tubular portion la. A pin 52 fixed by appropriate means is fitted into the two holes 44c and 44c2 of the yoke 44c of the spacer 44, and this pin 52 connects the connecting shaft of the tip 15b of the pitch adjustment lever of the blade 5. do the work.

It is noteworthy that, like the ball joint 9, the tip 15b of the pitch adjustment lever is connected to the elbow-shaped protrusion 44c of the spacer 44 in proximity to the ball D passing through the center of the spherical thrust bearing 3. As is clear from the lower part of FIG. 8, at the end of the lower plate lh of the hub 1, at the level of each blade 5, i.e., at the tip of the arm of the lower plate lh, there is a A stopper 54 of a known type is attached to the lower surface of the lower plate 42b of the yoke, and the stopper 54 is in an actuated state so that the rotor is stopped or rotates at a small speed. A protrusion 56 is provided which can sometimes cooperate with the stopper 543.

The simultaneous downward rotation of the four blades due to their own weight when the rotary blade is stopped is restricted by the cooperation of the stopper 54 in the operating state of each of the yokes, especially the protrusion 56 of the lower plate 42b. There is.

When the three rotor blades are rotated via the mast 2, the spherical thrust bearing 3 receives a resultant force in the radial direction due to the centrifugal force applied to each member of each blade 5. It is absorbed by the compression of section 3b. On the other hand, due to the action of various aerodynamic and inertial moments and forces acting on each blade, each blade is flapping due to deformation due to shearing around the center C of the spherical thrust bearing 3 of the elastic laminated portion 3c. A state of equilibrium is reached. The driving torque is transmitted to each vane via the strut 7, the strut also elongates slightly, and the vane 5 assumes a position slightly behind its neutral position when the rotor is at rest. During normal operation of the rotor and when the helicopter is in translational flight, the drag oscillations of each blade 5 are largely damped by the elastic adjustment struts 7, as described above.

Moreover, an axis D passing through the center C of the spherical thrust bearing 3, through which the ball joint 9 connecting the first end of the strut 7 to the base of the vane 5 via the baser 44 of the yoke and its elbow-shaped projection 44a; That is, since it is close to the flapping axis of the blade 5, the flapping movement of the blade 5 around the bag D causes only a negligible compressive or tensile stress on the support 7, and the support 7 also It exerts only a slight elastic adjustment and damping effect on the flapping movements of the blades 5. The almost vertical movement of the end 15b of the pitch adjustment lever connected to the blade 5 is also possible because the end 15b of the pitch adjustment lever is connected to the pin 52 near the flapping axis D of the blade 5. , is similar. Moreover, since the stop 54 is retracted by the action of centrifugal force, the flapping of the vane 5 is no longer restricted downwards. When the rotor is stopped, the struts 7 connected to each blade 5 recover their length and shape and exert a restoring force on the base of the blade 5, returning the blade 5 to its neutral position and pushing the blade downwards. The deflection is again limited by the stopper 54, which returns to its activated state when the rotational speed of the rotor falls below a predetermined value.

A modification of the rotor hub shown in FIGS. 8-10 is partially shown in FIG. 11, in which like parts are numbered the same as before. . In this variant, the upper plate 1g of Hafu is still located at the center la
However, the lower plate lh is a sound B material separate from the upper part of the mast 2 of the rotor blade, and these three members, namely the center part 1a, the lower plate lh and the mast 2, are connected to their respective annular flanges. They are assembled together with four bolts via li, lk and 2b. In FIGS. 12 and 13, which schematically illustrate another embodiment of the present invention, the same numbers are given to the same parts as in FIGS. 8 to 10.

This example is also the same as the previous one except for the following points.
. That is, in the embodiment shown in FIGS. 12 and 13, the base plate 44 fixed between the two plates 42a and 42b of the yoke connected to each blade 5 is directed in the direction of the front green of the blade 5, That is, in FIG. 12, the first elbow-shaped protruding portion 44a,
and a second elbow-shaped protrusion 44a2. The first elbow-shaped protrusion 44a of the blade pitch adjustment lever 44 is provided with tags 44c and 44c2, respectively, for fixing the connecting shaft 52 of the end 15b of the blade pitch adjustment lever in the Z direction.
Only the main arm 44c is provided, and the second elbow-shaped protrusion 44a2 is formed with a bore 44b, which is connected to the first weave of the strut 7 corresponding to the blade 5 of the ball joint 9. A fixing pin 49 passes through it. In this embodiment, each strut 7 for elastic adjustment of drag has a corresponding vane 5
Since it is located on the trailing edge side of the rotor blade, it is slightly compressed during normal operation of the rotor blade. As in the previous embodiment, the ball joint 9 connecting the end 15b of the pitch adjustment lever of the blade 5 and the first end of the strut 7 are both close to the flapper saw axis D of the blade 5'; This provides the same effect as described above. The embodiment of the retractable stopper 54 is optional.

In addition, the base plate 4 shown in perspective view in FIGS. 10 and 13
The same applies to the shape and embodiment of No. 4. For example, instead of mounting together the articulating shaft at the end of the pitch adjustment lever and the ball joint at the first end of the drag elastic adjustment strut in a single spacer, each blade of the rotor according to the invention The connected yokes can also be provided with two separate spacers to separately perform the two functions of a single spacer as described above. The yoke for connecting the base of each blade 5 to the spherical thrust bearing 3 consists of two rigid plates 42a and 42 connected by at least one spacer 44.
Instead of being formed according to b, it is also possible to produce it in other ways, for example as a single cast or machined part with a hollow part suitable for freely passing the spherical thrust bearing 3. The yoke could also be integral with the base of the blade 5, but in this case, of course, the construction would be simpler, but the blade would not be foldable. The method of fixing the ends of the two plates 42a and 42b of the yoke, which are closer to the huff, is also arbitrary. The same applies to the embodiment of the spherical thrust bearing 3. The reinforcing ribs lj of the lower slope lh can also be omitted if the thickness of the lower plate lh is made sufficiently thick. The hub, in particular its central part la and the two plates 1g and lh, can also be formed integrally with the upper part of the mast 2 of the rotor, for example by casting.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the base of a blade of a main rotor of a helicopter according to the present invention and a part of a hub connecting the base of this blade. FIGS. 2 and 3 are respectively similar to FIG. FIG. 4 is a plan view of another embodiment of the main rotor of a helicopter with four blades that are foldable in the plane of the rotor. be,
5 is a sectional view taken along the line V-V in FIG. 4, FIG. 6 is a partially cutaway front view of the tail rotor of the helicopter according to the present invention, and FIG. 7 is a sectional view taken along the line V-V in FIG. FIG. 8 is a cross-sectional view taken along the line W of FIG.
FIG. 9 is a partial sectional view taken along line K--K in FIG. 8; FIG. FIG. 9 is an exploded view of the hollow yoke connecting the base of the blade to the corresponding spherical thrust bearing; FIG. 11 is a modification of the hub of FIG. 8; FIG. , is a cross-sectional view similar to FIG. 9, showing another embodiment of the rotary blade of the present invention; FIG. 13 is a perspective view of a spacer forming a part of the hollow yoke in the embodiment of FIG. 12; be. 1...Hub, la...Center, 2...
・・・Mast, 3... Spherical thrust bearing, 5...
...Blade, 7... Support column, 15... Pitch adjustment lever, 16, 16a' 16b, 17a, 17b.
...Stopper, 17... Reciprocating ring, 2
0a, 20b...Fork-shaped member, 21A, 2
1B, 21a, 21b...pin, 42a, 42b...
...Yoke upper plate, lower plate, 44...0...Subesa. ``Misaki Kagami. Gikku humiliation. 3 Tsuru 4 Robi I 2nomiya-6 Hayabusawa Street Yuba Shio ○ Carp ~ Be Hiroshi Q Fly Arrival

Claims (1)

[Scope of Claims] 1. At the base of each of the blades by an elastic adjustment strut that is fixed to the rotor mast and has a layered spherical thrust bearing and an elastic damping member that cooperates with the fork-like member. In a rotorcraft rotor wing having an articulated rigid hub, a pitch adjustment lever for each of the blades, and means for limiting flapping movement of the blades, the resilient adjustment strut each consisting of alternating stacks of metal plates and plates of viscoelastic material having a high resilience to deformation to form a frequency adjustment device, one end of each of said struts being connected to one another via a ball and socket joint. It is connected to the base of two blades, and the other end is connected to one point on the hub by a ball joint so that the strut is always slightly inclined with respect to the corresponding blade, and the center of one ball joint is A rotor blade characterized by its proximity to the flapping axis of the vane passing through the center of a corresponding layered spherical thrust bearing. 2. The peripheral edge of the hub is a flat ring with a convex polygonal or approximately circular peripheral edge, and has the same number of openings as the number of blades in the axial direction of the rotor, and each of the layered spherical thrust bearings and the end of the forked piece of the fork-like member affixed to the base of the corresponding vane, the second end of each of the resilient adjustment struts being attached to the vane. A patent claim characterized in that the connected spherical thrust bearing and the spherical thrust bearing connected to the blade immediately before or after the blade in the rotation direction are connected to one point on the periphery of the hub via a ball joint. The rotor blade according to scope 1. 3. Claim 2, wherein the fork-shaped member is an extension of the base of the blade, and the tip of the branched piece of the fork-shaped member is fixed to a supporting member of a corresponding spherical thrust bearing. The rotor blade described in . 4. Said fork-shaped member is basically constituted by a radially arranged yoke, the end of which remote from the hub is connected by two pins substantially perpendicular to the plane of the rotor. The other end of the yoke is fixed to the base of the corresponding blade, and the other end of the yoke is connected to the support member of the corresponding spherical thrust bearing, which is integral with each other and is disposed on both sides of the peripheral edge of the hub without contacting the peripheral edge of the hub. The rotor blade according to claim 2, characterized in that it is composed of two rigid plate-like members that are fixed to each other. 5. The yoke is basically constituted by two rigid plates that are integral with each other and are substantially parallel to each other and to the peripheral edge of the rotor blade in the form of an annular plate. A rotor blade according to claim 4. 6. Rotate the blade by making it possible to remove one of the pins that fix each yoke to the base of the blade, and rotating this blade around the other pin that fixes the yoke. The rotor blade according to claim 4 or 5, characterized in that the rotor blade can be folded within the plane of the blade. 7. Claim 1, characterized in that the hub constitutes a single metal member together with the mast of the rotor blade.
The rotor blade according to any one of items 6 to 6. 8. The hub is basically a composite body composed of layers of woven fabric made of synthetic fibers or mineral fibers with high mechanical strength, coated with a hardened synthetic resin, hardened and stacked, Claim 1, characterized in that the hub is fixed to the upper end of a metal mast of the rotor.
The rotor blade according to any one of items 6 to 6. 9. Claim 1, characterized in that said ball joint whose center is close to the flapping axis of the vane is a ball joint connecting a hub to the second end of each one of said struts.
The rotor blade according to any one of items 8 to 8. 10. Claims 1 to 9, characterized in that the pitch adjustment lever is connected to each blade and is fixed to a fork-shaped member connected to the same blade on the opposite side of the column. The rotor blade described in any of the above. 11. The rotor blade according to claim 10, wherein the tip of the pitch adjustment lever of each blade is close to the flapping axis of the corresponding blade. 12. Said means for limiting the flapping movement of the vanes are mounted in a known manner around the mast on the underside of the hub and for each vane are attached to that mast by the lower end of a corresponding fork-like member. Claim 2 comprising a reciprocating ring cooperating with a stop supported at the proximal end, the stop being arranged to limit downward flapping of the corresponding vane. The rotor blade according to any one of Items 1 to 11. 13. A tail rotor blade for a helicopter according to any one of claims 1 to 11. 14. Said means for limiting the flapping movement of the blades comprises, for each blade, a stop supported at its end proximate to the mast by two branches of a corresponding fork-like member; are arranged to limit the flapping of the corresponding vane on either side of the plane of the rotor by cooperating with another respective stop of said means, one of said stops being fixed to the mast of the rotor. 14. The tail rotor according to claim 13, wherein the other stopper is fixed to an extension of the pitch adjustment lever in one direction. 15 The hub extends the mast of the rotor and has a central body having an upper plate and a lower plate, and between the edges of the two plates one of the rigid members of each spherical thrust bearing is provided with a rigid spacer. by means of fork-like members in the form of radially arranged yokes, the base of each vane being hollow for free passage of the corresponding spherical thrust bearing. The first end and the second end of each support column are respectively fixed to the other rigid member of the spherical thrust bearing, and the first end is connected to a yoke connected to the corresponding vane through a ball joint, and the second end is connected to a yoke connected to the corresponding vane. are respectively connected to appropriate locations on the central body of the hub.
The rotor blade described in section. 16. The rotor blade according to claim 15, wherein the center body of the hub, which is integral with the upper plate of the hub, is fixed to a lower plate which is integral with the upper part of the mast of the rotor blade. . 17. The rotor according to claim 15, characterized in that the center body and the lower plate of the hub, which are integral with the upper plate of the hub, are fixed to the upper part of the mast of the rotor blade by the same bolt. Wings. 18 The upper and lower plates of the hub are thinner than the blades,
The rotor blade according to any one of claims 15 to 17, characterized in that a reinforcing rib is provided on the lower surface of the lower plate. 19 Two rigid plates provided with holes through which the yokes connected to each vane freely pass the corresponding spherical thrust bearings, with the holes and the bases of the vanes separated from the hubs of the two plates. and at least one spacer fixed between the two plates in the space between the means fixed to the ends of the two plates. The rotor blade according to any one of Item 18. 20 The tip of the plate of the yoke near the hub is at least partially fitted into the other rigid member of the corresponding spherical thrust bearing, and is fixed to this rigid member by a plate fastened with screws. The rotor blade according to claim 19, characterized in that: 21 The base of each vane is fitted into the corresponding two plates of the yoke with a slight play between the tips of the two plates remote from the hub. They are secured to each other by two fastening pins that are substantially perpendicular to the plane of the wing, and at least one of the two fastening pins is removable so that the blade can be attached to the other fastening pin. 21. The rotor blade according to claim 19 or 20, wherein the rotor blade can be folded within the plane of the rotor blade by rotating around . 22 A spacer fixed between the two plates of the yoke protrudes from the yoke on the front edge side of the corresponding blade to form an elbow-shaped protrusion, and the spacer forms an elbow-shaped protrusion that connects the connecting shaft at the tip of the blade pitch adjustment lever and the corresponding support. Claims 19 to 21, characterized in that the elbow-shaped projection is configured such that the ball joint at the first end of the blade can be mounted in close proximity to the flapping axis of the blade. Rotary wing described in Crab. 23. A spacer fixed between two plates of the yoke projects from the yoke on the leading edge side of the corresponding vane to form first and second elbow-shaped projections, respectively;
The connecting shaft at the tip of the blade pitch adjustment lever can be attached to the first elbow-shaped protrusion, and the ball joint at the first end of the corresponding column can be attached to the second elbow-shaped protrusion. A rotor blade according to any one of claims 19 to 21, characterized in that it comprises two elbow-shaped protrusions. 24. Any one of claims 15 to 23, characterized in that the ball joint at the second end of each strut is fixed to the thickened annular portion of the tubular central body of the hub. The rotor blade described in . 25. The means for limiting the flapping movement of the blades is provided for each blade by at least one retractable means in flight by centrifugal force and provided at the tip of the lower plate of the hub.
Claims characterized in that the stoppers are arranged to cooperate with respective yokes connected to the corresponding vane, thus limiting downward flapping when the rotor is at rest or when rotating at low speeds. The rotor blade according to any one of the ranges 15 to 24.