CN111315653A - Rotor or propeller blades with dynamic optimization of shape and other properties per revolution - Google Patents

Abstract

The invention provides a blade for a horizontal-rotation marine propeller or a horizontal-rotation aerial rotor wing, which has the following dynamic and real-time performances according to the instruction of a control system: bending along the chord line of the blade in any desired manner, changing its relative pivot point position, extending by stretching or contracting the trailing edge to change its level, and possibly having left-right variability, as necessary, to turn the flap in either direction along the trailing edge or to allow it to be turned in flow. In addition, the blade may also have one or more resilient trailing edges whose stiffness is dynamically variable under control of the control system and which may vary differentially along the blade span. To allow the leading and trailing edges to operate in reverse in a counter-current flow or other conditions, the blade has edges that: rigid when used as a leading edge and bendable when used as a trailing edge. The blade also has the property of varying its cross-sectional side thickness and varying its shape. Finally, the blade has a flow permeability on a large surface according to the instructions. These capabilities will allow each blade controlled by the control system to be continuously optimally adjusted to its immediate operating environment as it passes through each rotational orbit, and to take full advantage of its immediate operating environment.

Description

Rotor or propeller blades with dynamic optimization of shape and other properties per revolution

Technical Field

The present invention relates to blades for rotorcraft and rotors, and in particular to blades for rotorcraft and propellers for non-circular tracks.

1. Description of the Prior Art

Blades for non-circular orbit cyclopropellers and rotors are currently known that are of a fixed cross-sectional shape, such as described in U.S. patent No. US 8,540,485. However, the patent No. PCT/IL2013/050755 describes a type of electromagnetic rotor or propeller in which the blades guided by the control system follow their own independent orbital motion, and the blades are designed to be flexible in cross-section, either by hinges along the entire length of the blade or by using known suitable elastic materials, such as elastomers. The dynamic variability of the blade cross-sectional shape is useful for providing fishtail or wave propeller type propulsion, and may be used for other purposes, such as controlled generation and shedding of blade trailing edge vortices, and corresponding dynamic optimization of blade shape in coordination with different operating conditions along the blade track. In the above-cited patent application, the blades are bent by means of a magnetic force vector acting on magnetic feet mounted at the ends of the blades. I.e. bending the cross-section of the blade by external forces acting on the blade. Such electromagnetic propellers or rotors have this property, but known flat rotors or propellers are not, and dynamic blade cross-sectional shape variability is highly desirable for them. In addition to the above-referenced patent applications, the related art of flat-rotor propellers and rotors does not find any dynamic blade axis position variability. Said patent application describes the position of a virtual axis point on the blade chord, but does not describe the variability of the relative position of the physical axis points, nor is this characteristic found in the prior art. Dynamically varying planform shapes are known as variable shape airfoils, but are not known in the case of flat rotary rotors and propeller blades, for which the latter are required for different reasons-the need to vary the size of the blade trailing edge vortices and dynamically control the current position of each blade trailing edge along the blade trajectory, thereby controlling the position of the blade trailing edge vortices and their shed flow. Rotatable trailing edge flaps have long been a feature of aircraft fixed wing and helicopter rotor blades, but not of the rotor and propeller blades, and in this regard they would be useful to generate blade trailing edge vortices, control their magnitude and shed in a controlled manner or to avoid or minimize vortex generation by adversely affecting the portion of the blade track, or to propel fishtail blades. Leading-edge slats and slots are well known aircraft fixed wing features for lift enhancement and stall prevention, but to counteract the effects of strong local cross-track flow and/or to counteract the effects of dynamic pressure differentials across the wing and propeller blades when they are adversely affected, most surfaces of the rotor and propeller blades have "on" or "off" substantially unobstructed flow permeability (particularly the trailing edge portion of the blade) which, when needed, acts on a portion of the track of the inner blade for each revolution of the rotor or propeller, for entirely different reasons and configurations, and cannot be found in the prior art. It is known to provide examples of flexible blade trailing edges as helicopter rotors, but providing a plurality of flexible blade trailing edges on different sides or on the same side of the blade axis point for co-or counter-bending, equipped with structural elements of dynamically variable stiffness and of highest achievable stiffness, may be very useful for certain types of flat rotary rotors or propulsors operating with respective importance for aeroelastic or hydroelastic effects comparable to that of conventional lift generation, and not found in the prior art. When the leading and trailing edges of the blade are operated in reverse in a reverse airflow regime, and in other cases, it is highly desirable to switch between rigid and flexible states of the leading and trailing edges, but this function is not found in the prior art. In blade leading and trailing edge exchanges and other situations, it is useful to vary the cross-sectional side thickness of the blade, but this is not found in the prior art.

2. Objects and advantages

One of the purposes is to provide a blade cross section shape dynamic bending method based on blade power for any blade of a flat rotary propeller and a flat rotary rotor.

Another object is to provide the blades of the above-described propellers and rotors with the ability to dynamically vary their physical pivot point location along the blade chord to control the relative magnitudes of the blade leading and trailing edge vortices.

Another object is to provide the propeller and rotor blades with the ability to dynamically change the planform of the blade by telescoping the blade trailing edge extension, which can be differentially extended across the blade according to the respective current aerodynamic and hydrodynamic profiles at the two ends of the blade to control the size of the blade trailing edge vortex, shape along the span, movement along the span, creation and shedding.

Another object is to provide the blades of the propeller and rotor with trailing edge flaps that are dynamically rotatable by airflow or power in either direction to account for blade trailing edge vortices and other airflow affecting the blade trailing edge.

Another object is to provide the blades of said propulsor and rotor with at least one flexible edge and make the stiffness of this edge dynamically variable in real time, with any variability along the blade span, to better control the hydro-elastic and aeroelastic effects separately.

Another object is to provide the blade with the ability to vary its lateral cross-sectional thickness and shape accordingly when the leading and trailing edges are reversed to operate in a reverse airflow regime or other situation where a change in blade cross-section is required.

Another object is to make the previously rigid leading edge flexible and the previously flexible trailing edge rigid in reversing the leading and trailing edges of the blade to effect the reversal of the role.

Another object is to provide a large portion of the blade, especially the trailing edge portion, with an on-demand cross-blade flow permeability that can be started or stopped by a control system at appropriate locations along the blade track to counteract the effects of strong local cross-track flow or the effects of opposing surface dynamic pressure differences of the blade when such dynamic pressure differences adversely affect.

3. Brief description of the drawings

FIG. 1 (FIG. 1) is a schematic view of a vane incorporating a built-in linear actuator which acts to change the relative angular positions of adjacent segments so that their cross-sectional shapes dynamically change.

Fig. 2(fig.2) is a schematic view of a blade with elastically bendable plates between which are mounted electroactive polymer segments of varying sizes that vary according to the application of voltage, thereby dynamically bending the cross-sectional shape of the blade.

FIG. 3(FIG.3) is a schematic view of a vane having a shaft-attached support that carries an actuator to dynamically move the vane relative to the shaft to change the position of the vane relative to the shaft point.

FIG. 4 (FIG. 4) is a schematic view of a blade tip with an actuated trailing edge extension flap.

Fig. 4A (fig. 4A) is a side view of another different design of a blade with a movable extension flap.

FIG. 5 (FIG. 5) is a side view of a blade with a rotatable blade trailing edge flap.

FIG. 6 (FIG. 6) is a schematic blade tip with two bendable edges with differentially variable stiffness along the span, oriented in opposite directions, suitable for reversing the leading and trailing edges of the blade.

FIG. 7 (FIG. 7) is a schematic view of a blade tip with two variable edge flaps on opposite edges of the blade and operating toward the same.

FIG. 8 (FIG. 8) is a side view of a blade with variable cross-sectional side height.

FIG. 9 (FIG. 9) is a partial side view of a vane having "on" or "off" flow permeability.

4. Description of the preferred embodiments

The first embodiment of the invention (fig. 1) is a blade (1a) consisting of a number of parallel segments (1) connected either by hinges (2) or by bendable connections, thus forming a surface with a bendable cross-section. Possible configurations of such a blade may include sections of unequal size along the chord line, e.g., the first section from the leading edge of the blade being the longest. The segments will carry plates with actuators (3) spanning the inter-segment gap and which may be miniature as appropriate, for aerodynamic wing blades such as electroactive polymer actuators, piezoelectric crystal stack actuators or amplified piezoelectric actuators with fast acting speeds, and for much slower hydrodynamic wings such as electromagnetic actuators, electroactive polymer actuators or smart memory alloy based actuators. A cross-gap resilient flap may be provided from one section to the next. The flap can be made to slightly elastically press against the surface of the next segment, so that coverage of the gap is maintained also when adjacent segments change relative position. For aerodynamic wings, the contact surface of the section pressed by the flap may be coated with a low friction surface and/or lubricated with air, for example to divert part of the ambient airflow into the contact area between the section and the flap. Surface treatments or coatings suitable for cooperating with water lubrication operations may be applied to the hydrodynamic foil. Similar coatings may be applied to the surfaces of the flaps that slightly compress the sections. Alternatively, the upper and lower blade surfaces of the segments may be provided with a resilient covering, and may be made of, for example, an elastomeric material. A different embodiment of this first embodiment is particularly suitable for marine propellers, as shown (fig.2), where the elastic plate (5) extends along the chord line and a separation plate (6) is mounted perpendicular to the elastic plate. The blade structure combines the flexibility of the cross section with the rigidity in the wingspan direction brought by the splitter plate (6). Between the separating plates and attached thereto, electroactive polymer sections (7) connecting the circuits are mounted. The surface of the blade is covered with an elastic covering film (8), which can be made of, for example, an elastomer. In yet another version of this first embodiment, a rotary actuator would be used at the hinge between the sections (1) in a similar manner to that used in the fourth embodiment for rotating trailing edge flaps, but in the first embodiment the rotary actuator would be used to change the relative levels of adjacent sections and thus the shape of the blade. A further version of the first embodiment has bars made of smart memory alloy with which the segments (1) are connected, said bars being bent according to the instructions of the control system to change the relative levels of adjacent segments and thus the shape of the blade. It is furthermore an option to place pressure/flow sensors and emitters, e.g. infrared light or radio, on the blade surface to communicate sensor data and provide feedback to the control system about the exact position of the blade parts.

The second embodiment will comprise a vane (fig.3) with a fixed cross-sectional shape or variable shape, fitted at both ends with support plates (9) slidably mounted on a short coupling track (10). The respective ends of the actuator (11) are attached to said shaft (12) connection track, while the opposite ends of said actuator are attached to the carriage. Examples of suitable fast acting actuators are actuators based on electroactive polymers or piezoelectric amplification. The carriages may be mounted in a further pair of carriages and the actuators attached to the inner and outer carriages in the same way as the support plate (9) and stub axle connection track (10) described above are connected. The aim is to move the carriages with actuators in a staggered manner to increase the distance of movement of the blades relative to the pivot point, since the actuators required for aerodynamic wings with real time pivot point relative position variability must be very fast acting, but are usually short in stroke-for example piezoelectric crystal based actuators can be used with suitable known amplifiers. Translational movement of the blade relative to its pivot point will result in tangential redistribution of its mass forward and backward, which may be neutralized using a method similar or equivalent to the balance-canceling method described in U.S. patent No. US 8,540,485 and/or in patent application No. PCT/IL2013/050755, or using other known balance-canceling methods and/or damping means.

The first version of the third embodiment of the blade of the present invention (fig. 4) comprises a blade having a fixed shape or a flexible blade as described in the first embodiment. On suitable elements of this blade structure 2 fast-acting linear actuators (13) will be mounted, which are attached to a pin (14) in a rotatable connection. The left side of the pin (14) is mounted on a movable support (15). The support is movable along a short track (16) to accommodate differential movement of the left and right sides of the trailing edge extension (17), which is made of an extremely light material, such as carbon nanotube film or the like. In a second version of this embodiment (fig. 4A), the conveyor belt (13a) is placed on a larger diameter shaft (14A) and shaft (14 b). Connecting rods (15a) are attached to the conveyor belt and to a retractable trailing edge extension (17), while counterweights (15b) are attached to opposite branches of the conveyor belt (13 a). The arm (16a) with the follower bar/roller (16b) is mounted on a dedicated trailing edge control track (17a), which may be of fixed or variable shape. In operation, the shaft (14a) may also be coupled by a rotary actuator (not shown) instead of an arm with an orbital follower link. Many other different design solutions are possible to accomplish the simple task of extending and retracting the trailing edge extension, but even if the details differ, they are generally within the scope and spirit of the invention. The telescoping of the trailing edge extension will result in forward and rearward redistribution of its mass, which may be neutralized using a method similar or equivalent to the balance cancellation method described in U.S. patent No. US 8,540,485 and/or in patent application No. PCT/IL2013/050755, or using other known balance cancellation methods and/or damping means.

A fourth embodiment of the blade according to the invention (fig. 5) comprises a rotatable flap (18) attached to the blade body by a hinge. Along the tip of the flap and corresponding to the position of the blade body, there will be a stop (20) with a bumper to limit the maximum rotation amplitude of the flap in both directions. A fast acting rotary actuator (21) with a clutch (22) is mounted coaxially with the hinge. The key (23) will ensure that the flap (25) rotates together with the shaft (24) to which the hinge (26) is connected. Optionally, a micro-transmitter, such as infrared, may be placed on the flap to indicate to the control system the actual position of the flap. The rotatable flap (18) may optionally also include a bendable trailing edge as described in the fifth embodiment. The rotatable flap in this embodiment may also be rotated without a fast acting actuator, but using an arm with a driven lever (not shown) connected to the shaft (24) and mounted on a dedicated flap control track, in the same manner as described in the second version of the third embodiment and shown in fig. 4A. It would be desirable to balance this rotatable flap about its axis of rotation, particularly for airborne rotor applications where speed is much faster.

A fifth embodiment (fig. 6) of the blade (1a) will comprise a bendable trailing edge (27) provided with a stiffening rib (28) extending from the side of the bendable trailing edge where it is connected to the blade structure to the free end of the bendable trailing edge. The distance between the reinforcing ribs (28) is predetermined. The rib post will be made of a resilient material, such as a plastic of the type used for plastic springs, resilient copper alloys or spring steel. The rib post in one version of this embodiment is substantially in the form of a hollow tube containing oil or other incompressible balloon-free liquid, sealed at one end and closed at the other end by a piston or, if applicable, by an elastic membrane suitably resistant to high pressure for a given diameter of the hollow tube, and said piston or membrane is moved more or less to the inside or outside of the hollow cavity of the tube as required by an actuator, for example of the type based on piezoelectric or electroactive polymers, in a controlled manner according to a predetermined mathematical function or formula describing the movement over time, by means of a frequency control system or according to specific instructions of the control system. When the piston or membrane is pressed inwards, high pressure is generated in the cavity in the tube, tensile stress is formed in the tube wall, and for certain types of tube wall materials, such as plastics, significant complete expansion is caused, and due to these factors, the rigidity of the rib post is increased, and vice versa when the piston or membrane is moved outwards. Alternatively, the piston or membrane may be external to the rib (28) of the hollow tube, with a high pressure input into the hollow tube via a suitable inlet, or an inlet internal to the hollow tube may be used, for example, which may comprise a suitable electroactive polymer which changes volume under the action of an electrical voltage, thereby changing the pressure within the tube. In another version, particularly suitable for marine propellers at low rpm (revolutions per minute), such reinforcing ribs may comprise a resilient beam made of the same material as described above for the rib post, having an elongated cross-sectional shape, for example elliptical or oval, and mounted within a circular tube. When the actuator rotates the beam relative to the plane of the blade, its area moment of inertia relative to the plane and corresponding to its stiffness will vary, if desired by a factor of several. Another way to implement this stiffening rib in an airborne rotor at higher rpm is to use it as a leaf spring consisting of two or more flat strips of predetermined thickness, the contact surfaces of which are provided with an electrically conductive layer or coating, and between which there is a thin layer of electro-rheological fluid. The surface of the flat strips may be intentionally roughened or roughened to increase the viscosity change of the liquid under the frictional forces between the flat strips. The viscosity of the liquid is controlled by the action of a voltage, up to a rigidity which is achieved and thus controls the stiffness of the miniature (where appropriate) leaf springs used to reinforce the ribs. These and other embodiments of such reinforcing ribs with variable stiffness are described in detail in patent application No. PCT/IL2015/05021, "smart springs and combinations thereof" and patent application No. PCT/IL2016/051195, "springs with dynamically variable stiffness" as leaf springs and coil springs. The variation in stiffness of the stiffening ribs (28) may be differential along the blade span, which will affect the shape of the vortex formation and its possible movement along the bendable edge. Said flexible edges along the blade span may be provided at a number of locations along the blade chord, for example (fig. 6) facing in opposite flexible edges along opposite edges of the blade on both sides, in a direction defined from its mounting side to the movable free side. This feature is particularly useful in situations where it is desirable to operate in a reverse airflow, or where otherwise reversing the leading and trailing edges would have a beneficial effect on the current instantaneous orbit position of the blade and its current pitch angle. In this case, the control system makes a decision that the leading edge becomes rigid and the leading edge becomes flexible to a suitable degree. Alternatively, depending on what type of operating environment the blade is designed for, the bendable edges may also be mounted facing the same direction (fig. 7) on different sides or the same side with respect to the blade axis point. In both cases they require spanwise openings in the blade surface that are large enough in a predetermined dimension to operate with a bendable edge at a location other than the leading edge and the trailing edge.

In a sixth embodiment of the invention, the blade will have dynamic side thickness variability to optimize the side profile of the blade cross-section, or also the spanwise side profile, for different operating conditions and mechanisms along the blade track in one revolution. In a fifth embodiment, this feature would also be required when the leading and trailing edges are reversed and a corresponding change in blade side profile is required to match the reversal. The blade shown in figure 8 will comprise a substrate (29) of fixed or variable shape as described in the first embodiment above and a flexible cover layer (30) of a material having the required flexibility, stiffness, resilience and fatigue resistance, for example a single layer graphene sheet or carbon fibre sheet for aerodynamic applications and a spring steel sheet or a resilient copper alloy sheet or carbon fibre sheet for marine propellers. The sheets are preferably mounted on both the upper and lower sides of a base plate (29) and are supported by a plurality of actuating elements (31) mounted on the base plate in a predetermined pattern and at predetermined intervals. The actuating elements may be implemented, for example, as memory alloy conical spirals whose shape can be varied between a conical shape when fully extended and a flattened spiral when fully retracted, each such element or a predetermined set of elements being individually position-controlled by a control system, for example, a row of elements attached to a single flattened structural strip (33) extending along the blade span. Typically the distance moved within a row of actuators is the same, but it is also possible to have the rows or groups of actuators move differentially along the span of the blade to achieve the spanwise profile variability of the blade. Another embodiment of such a ganged actuation element is the use of an inflatable and extendable length hose, pneumatically inflated for airborne rotors and pneumatically or hydraulically inflated for marine propulsors, mounted on a base plate (29) and attached to a flat structural bar (33). Or for aerodynamic applications, such actuating elements may also use piezoelectric actuators with amplifiers that act much faster and can be used to dynamically change the shape of the sheet in each rotor rotation. As the cross-sectional side profile of the sheet varies, the length of the curve also changes. The length change can be achieved by using a sheet divided into strips (32) of predetermined width and partially overlapping. As the height difference between adjacent slats varies, the length of the curve may be varied by varying the amount of overlap between adjacent slats. Or may be connected along the span of adjacent slats using tongues and grooves. If one web covers more than one row of actuating supports, the web is attached to one row of said actuating supports in a known manner to facilitate its movement relative to the other said row of supports, for example using suitable flexible rails attached to the web, on which actuating supports the rotors or sliders are mounted. Alternatively, a cover layer (not shown) of elastomer of variable length may be applied to the web to cover the edges of the web. Many types of such actuator supports and other actuation means may be used to bend the sheet, but even if the details differ, they are generally considered to be within the spirit and scope of the invention. The second version of the sixth embodiment is particularly suitable for marine propeller blades. It will comprise pads (not shown) made of a suitable electroactive polymer or other suitable material capable of changing its volume and/or shape in a predetermined manner and degree under the action of a voltage, attached to a fixed or flexible substrate (29), possibly on both sides of the latter, and possibly with a protective covering consisting of a thin sheet or a plurality of strips possibly partially overlapping, for example made of elastomer, spreading their joint surfaces on the respective surfaces of the blade on which they are mounted. For both versions of the sixth embodiment, the movement of the web or solid slab is facilitated by lubricating the bearing surfaces, with sea water lubrication for the marine blades and air lubrication for the air blades. The water or air flow for lubrication may be forced or directed around the blades.

The seventh embodiment of the inventive vane will have a controllable "on" or "off" state and a substantially unobstructed flow permeability over most of its surface to mitigate the effects of very strong cross-track flow encountered on some tracks that might otherwise be good. These flows can produce very significant buoyancy lift or negative thrust pulses, respectively, but there are other specific situations where it can be useful to have the permeability produced according to the control system instructions. Both side surfaces of the blade (fig. 9) will have apertures (34) of a size and location matched to cover a set of rotatable slats (35) similar to a louvre, which may extend along or perpendicular to the span of the blade, which is more desirable vertically as this may be the least disturbing to the flow across the blade. Between the apertures in the surface covered by the louvers will be channel walls (36) to direct and laterally control the flow between the apertures through the vanes. The axis of rotation (37) of the slats in the shutter may have gears or toothed sectors (38) which may be micro-sized as appropriate, preferably at both ends of the slats to prevent twisting thereof, said gears/toothed sectors being engaged by a carriage (39) or toothed belt driven by an actuator. For lightweight airborne applications, a chord-like torque force may be applied to both ends of the slats, without a rotating shaft, and the slats may be attached near the edges by a movable common push/pull link actuated by a linear actuator. To counteract the aerodynamic forces generated by a large number of slats turning together, half of the slats may be turned in one direction by one link and the other half in the other direction by the other link. The actuator should have locking capability or should have a separate device (not shown) of known type operatively associated with the push-pull link or bracket (39). Alternatively, the flow may be predicted by unlocking the actuator or the separate locking device, allowing the flow to turn the slats to the open position, and then returning the slats to the closed position by actuating a linkage or the above-described string-like torque with sufficient rotational stiffness.

5. Sketches and diagrams

Is provided separately.

6. Operation of

In operation, the blade of the first embodiment (FIG. 1) will bend its shape as the control system selects the mode of operation. The bending will be produced by the actuator (3) located in the gap between the segments (1) changing its relative distance from the attachment point of the adjacent segment (1) according to the command of the control system, thus changing the relative angular position of the segments and thus the blade shape. Under the action of the actuators coordinated by the control system, the blades will perform a bending action, such as a fishtail motion or a propulsive-type wave motion, mainly formed by their end sections, or continue to assume different curved profiles to generate an optimal lift/thrust suitable for the operating environment at the present moment. Another different version of this embodiment, as shown (fig.2), will operate as follows: the control system will activate the electroactive polymer sections (7) in a coordinated manner, which will expand and contract, pushing and pulling the separator plates (6), causing the elastic plates (5) to bend, and thus causing the entire blade to bend as directed by the control system. The blades may also use pressure/flow sensors placed thereon to make the control system fully aware of the current flow conditions around the blades. It will send data to receivers located elsewhere on the propeller/rotor structure and may also send signals such as infrared light along with it, providing feedback to the system to determine the exact position of the blade components.

In the vane operation of the second embodiment (fig.3), the actuator will, upon command of the control system, change the distance between its attachment point to the shaft stub rail (10) and the vane carriage, thereby moving the carriage, i.e. the vane loaded thereon, relative to said shaft point (12), which will cause the relative magnitudes of the leading and trailing edge vortices to change. If more than one carriage is used for the staggered movement, the actuators will effect a corresponding movement between the nested carriages. As described in the first embodiment, in addition, blade pressure/flow data and position information may also be sent to the control system.

In a third embodiment (fig. 4), the actuator (13) will move on command of the control system to move the pin (14) mounted on the moveable support (15), thereby moving the trailing edge extension (17) either inwardly or outwardly relative to the trailing edge of the blade. The actuators (13) are differentially movable to provide different positions for the pins (14) and thereby to position the right and left corners of the trailing edge extension at different distances from the trailing edge of the blade. Another design (fig. 4A) has a radial arm (16a) with rollers that follow the trailing edge extension control track (17a) and are turned to rotate the shaft (14A) and thereby drive the conveyor belt (13a) and the connecting rod (15a) attached thereto, which moves the trailing edge extension (17) outward and inward, while the counterweight (15b) moves in the opposite direction relative to the trailing edge extension (17). The motion of the trailing edge extension may be used to shed trailing edge vortices generated along the trailing edge, or to control the magnitude of the trailing edge vortices or the flow around the trailing edge, as desired. In addition, position information of the trailing edge extension and data from any pressure/flow sensors thereon may also be sent to the control system in the manner described above.

In a fourth embodiment of the inventive blade (fig. 5), when the control system releases the clutch (22), the rotatable flap will be released to move freely and will be pushed to either side of the blade by the flow, shedding the trailing edge vortex or attributing the adversely affected strong flow that occurs at a particular track inflection point to a falling flow without negative lift and other adverse consequences. Thereafter, the actuator (21) and clutch (22) will be re-engaged, as commanded by the control system, to align the flap with the rest of the blade or position it at some other angle as dictated by the control system. The flap can also be driven in rotation by power to achieve a fishtail propulsion movement of the flap or to control the generation of trailing edge vortices.

A fifth embodiment (fig. 6) of the blade of the invention has a flexible trailing edge (27) whose stiffness of the supporting ribs can be dynamically adjusted in real time in such a way as to control and optimize the instantaneous geometry of the curve formed by the flexible edge to optimize the vortex effect produced, thereby optimizing the blade performance in conjunction with its instantaneous current overall cross-sectional shape when operating at various state parameters, such as rpm, upcoming flow rate and direction, the geometry of the portion of the blade track traversed, and the current angle of attack (as applicable). The dynamic stiffness changes may be differentially implemented along the blade span to precisely control the generated vortices, their shape and motion along the span, and the lift or thrust generated. Since there may be multiple bendable edges on the blade of this embodiment, the point in time of vortex shedding by the control system on the upstream bendable edge will take into account its effect on the downstream bendable edge operation. The operation of the vane of the sixth embodiment is fully described in the description section and will not be repeated here, but is incorporated by reference as an integral part of this document.

The vane in the seventh embodiment operates as follows: upon command of the control system, the locking means (not shown) blocking the movement of the supports (39) or the common link connecting the rotatable slats (35) or the linear actuators (not shown) connected to said link are released, the slats (35) are then turned in a predetermined direction towards the side of the blade where the high dynamic pressure is expected. The same will then occur at the matching apertures on the other side of the vane as the dynamic pressure passes through the vane passages to the rotatable slats on the other side of the vane. The flow can then flow through the vane through the passages between the matching apertures that are opened. The next command of the control system may be triggered by a change in dynamic pressure or by the blade entering another part of its trajectory, according to which the actuator drives the carriage (39) or common link to return the slats to the original position, and the actuator or locking device will prevent any movement of the slats until the next system command comes. In the version of the seventh embodiment which employs torsionally fixed rotatable slats (35), the role of the control system can be reduced to merely controlling the locking means to prevent the aperture from opening when it should not open or when the position on the blade surface should not open at present, and the slats will be rotated by the dynamic pressure of the flow to open the aperture. When the dynamic pressure thereafter drops to a predetermined level, the torque force will return the slats to the original position, closing the apertures. Another possibility is to have the actuator or control system command to turn the slats in either direction independently of the flow over the slats, thus allowing the orifices to open or close in advance, ready for use, before the flow and/or dynamic pressure changes begin to act.

Claims (19)

1. A blade for a rotor or propeller comprising structural elements capable of providing cross-sectional bending properties to the blade in one revolution.

2. The blade of claim 1, wherein the structural elements comprise interconnected segments, and wherein the segments are positioned using the actuator assembly in accordance with instructions from the control system to dynamically form the currently desired blade surface.

3. The blade of claim 1, wherein said structural element comprises a resilient core against which the actuation member acts.

4. The blade of claim 1, further comprising an actuating member operatively connected to the carriage supporting the blade to dynamically vary the location of the blade's pivot point along the blade's chord line.

5. The blade of claim 1, further comprising an actuated extension flap, such that the overall length of the blade is dynamically variable.

6. A blade according to claim 5, having separate actuation members for differential extension of the tips of the extension flaps.

7. The blade of claim 1, having a rotatable flap mounted on a trailing edge of said blade.

8. The blade of claim 1, having at least one bendable edge with a structural member that is dynamically changeable in real time by the control system.

9. The blade of claim 1 having a flexible coating on at least one surface and an actuating element beneath said flexible coating to change the shape of said flexible coating.

10. The blade of claim 1 having an aperture partially covering its surface area, said aperture being covered by a rotatable slat which is rotated in real time by means to effect control of the flow across the blade.

11. Fixed-shape blades for a rotary flat rotor or propeller have structural characteristics that change their hydrodynamic properties in one revolution.

12. The blade of claim 11, wherein said structural feature that alters its hydrodynamic properties in one revolution is an actuating member to change an axis point along a chord line of the blade.

13. A blade according to claim 11, wherein the structural feature which changes its hydrodynamic properties in one revolution is an actuated extension flap, making the overall length of the blade dynamically variable.

14. The blade of claim 13, having independent actuators to differentially extend the ends of the extension flaps.

15. A blade according to claim 11, wherein the structural feature that changes its hydrodynamic properties in one revolution is a rotatable flap mounted on the trailing edge of the blade.

16. The blade of claim 11, wherein said structural characteristic that changes its hydrodynamic properties in one revolution is at least one bendable edge.

17. The blade of claim 16, wherein said edge comprises a structural member whose stiffness is dynamically variable in real time.

18. The blade of claim 11, wherein said structural feature that changes its hydrodynamic properties in one revolution is a bendable overlay on at least one surface thereof, and an actuation pattern under said bendable overlay to change the shape of the bendable overlay and thereby change the surface shape of the blade.

19. A blade according to claim 11, wherein said structural feature which alters its hydrodynamic properties in one revolution is an aperture which covers a substantial portion of its surface area, wherein said aperture is coated with a rotatable slat, and wherein control of flow through the blade is achieved by means for rotating said slat in said coating in real time.

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