Integrated two-blade fixed-pitch propeller and processing method thereof

Abstract

The present application relates to the field of aircraft blade structure design and manufacturing, in particular to an integrated two-blade fixed-pitch blade and a processing method thereof. A bushing and a chopped fiber preform are integrated at a blade root portion, the blade is connected with a rotor shaft through the bushing, and an outermost portion of the blade root portion is wrapped by a skin formed by a fiber reinforced composite material; the skin wrapped on an outer portion of the blade airfoil section is extended from the root skin; the blade is solidified with a long strip-shaped beam arranged along a center line of the blade on inner surfaces of upper and lower airfoils of the skin; a reinforcing rib is arranged inside the blade airfoil section, and forms a double-closed or multi-closed cavity structure with the skin; other regions inside the airfoil section are filled with foam.

Description

Technical Field

[0001] This invention relates to the field of rotor blade structure design and manufacturing for aircraft such as vertical take-off and landing vehicles, and specifically to an integrated two-bladed fixed-pitch rotor blade and its processing method. Background Technology

[0002] It is known that when a propeller blade rotates around its axis, the blade and the fluid medium generate relative motion. The fluid passes through the airfoil designed for the blade, creating a pressure difference between the upper and lower airfoils, thereby generating corresponding lift. Based on this principle, propeller blades are widely used in aircraft such as vertical takeoff and landing aircraft.

[0003] Compared to metallic materials, composite materials possess advantages such as higher specific strength and specific modulus, fatigue resistance, strong fracture resistance, good vibration damping performance, and high design flexibility. Currently, composite materials are widely used in the design and manufacture of structures such as rotor blades for vertical takeoff and landing aircraft. However, in common composite rotor blade skin layup, the entire layer is typically laid up in one continuous layer. The layup design does not consider the effects of stiffness, dynamics, and strength, resulting in low material performance utilization and poor economic efficiency.

[0004] Most vertical takeoff and landing (VTOL) aircraft rotor blades are designed to fit the rotor shaft interface, typically requiring a complex hub structure. Furthermore, the high-speed rotation of the blades around the rotor shaft generates significant loads. Ensuring the hub structure's load-bearing capacity leads to a heavy structural design, complex component design, poor economic efficiency, and hinders weight reduction. In contrast, the commonly seen one-piece two-blade rotor blades typically have their rotor shaft interface formed by drilling and machining the blades after curing, followed by inserting a bushing into the hole. This later drilling can easily cause damage such as delamination of the skin at the drilled area, and the later-inserted bushing may not fit tightly enough with the skin, leading to excessive blade vibration and fretting wear at the blade-buffer interface during use. Summary of the Invention

[0005] Purpose of the invention: To provide an integrated two-bladed fixed-pitch propeller and its manufacturing method to meet the lift or propulsion requirements of aircraft such as vertical take-off and landing vehicles.

[0006] Technical solution:

[0007] An integrated two-bladed fixed-pitch rotor blade includes: two integrated blades arranged at a 180° angle; the blade root includes a bushing and a chopped fiber preform solidified together; the blade is connected to the rotor shaft via the bushing; the outermost part of the blade root is covered by a skin formed of fiber-reinforced composite material; the skin covering the airfoil section of the blade extends from the root skin; long strip-shaped beams arranged along the blade centerline are solidified on the inner surfaces of the upper and lower airfoil surfaces of the blade; at least one "C"-shaped reinforcing rib is arranged inside the airfoil section of the blade, forming a double-closed or multi-closed cavity structure with the skin; other areas inside the airfoil section are filled with foam.

[0008] Furthermore, from the starting position of the airfoil section to the 0.5R position of the blade, 50%-75% of the inner skin is cut sequentially along the span direction; the remaining layers are laid up to the blade tip.

[0009] Furthermore, the cutting process is as follows: cut once every 0.1R, cutting 1-2 layers each time, with a cutting angle α of 45-60 degrees for bias cutting.

[0010] Furthermore, the reinforcing ribs are formed by fiber-reinforced prepreg layers.

[0011] Furthermore, the skin is made of glass fiber and carbon fiber woven prepreg.

[0012] Furthermore, fiberglass woven prepreg is laid on the outermost layer of the skin, with a laying direction of 0 / 90 degrees and 1-2 layers, while carbon fiber woven prepreg is laid on the inner layer of the skin, with 4-15 layers.

[0013] Furthermore, the carbon fiber woven prepreg accounts for 30%-50% of the fabric and is laid in the 0 / 90 degree direction, while the fabric accounts for 50%-70% of the fabric and is laid in the ±45 degree direction.

[0014] Furthermore, the chopped fiber preforms are made of glass chopped fiber prepreg or carbon chopped fiber prepreg.

[0015] Furthermore, the upper and lower end faces of the blade bushing should be 0-0.5mm lower than the surface of the blade root platform area.

[0016] Furthermore, the beams are made of carbon fiber prepreg unidirectional tape or unidirectional fabric.

[0017] Furthermore, the width of the spar is 50% of the blade reference chord length, and the thickness is 1mm-3mm.

[0018] Furthermore, the reinforcing ribs are made of carbon fiber woven prepreg with a layup direction of ±45 degrees and a layup number of 2-6 layers.

[0019] A method for manufacturing the above-mentioned integral two-bladed fixed-pitch propeller blade includes:

[0020] Step 1: Embed the bushing in the chopped fiber prepreg, and pre-cure the bushing and chopped fiber prepreg together in the preform mold to form the root preform;

[0021] Step 2: Lay the skin inside the blade mold and place the beam on the skin surface;

[0022] Step 3: Then assemble the root prefabricated part, front and rear cavity foam, and reinforcing ribs to form the inner core;

[0023] Step 4: Position the inner core in the blade mold that has been covered with skin and beams, and after the mold is closed, it is cured twice to form the blade.

[0024] Furthermore, the secondary curing temperature is lower than the glass transition temperature of the chopped fiber preform.

[0025] Beneficial effects:

[0026] This invention proposes a lightweight, simple, and low-cost integrated two-bladed fixed-pitch rotor blade and its connecting parts to meet the lift or propulsion requirements of aircraft such as vertical take-off and landing vehicles and helicopters.

[0027] This invention integrates two lifting blades into a single blade arranged at a 180° angle, achieving a balance of centrifugal forces on both sides. It eliminates the need for traditional hub structures, reducing structural components and weight.

[0028] The integrated two-bladed fixed-pitch rotor blade proposed in this invention features small beams made of fiber-reinforced unidirectional fabric or unidirectional tape on its internal upper and lower wing surfaces. These beams are located at the blade centerline, effectively increasing the blade's tensile and flapping stiffness and enhancing its load-bearing capacity. Simultaneously, they reduce blade deformation in the flapping direction, preventing interference with aircraft fuselage components and allowing for a more compact overall design.

[0029] The airfoil section of the integrated two-bladed fixed-pitch blade proposed in this invention is designed with "C"-shaped reinforcing ribs composed of fiber-reinforced prepreg layers, which together with the skin form a double-closed or multi-closed cavity structure to improve the torsional stiffness of the blade and enhance its load-bearing capacity.

[0030] The blade connector proposed in this invention has a simple structure, which can not only install blades and transmit blade lift, but also adjust the dynamic balance of blades after installation. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of an integral two-bladed fixed-pitch propeller blade according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of a typical cross-sectional structure at the root of an integrated two-bladed fixed-pitch propeller according to an embodiment of the present invention.

[0034] Figure 3 Schematic diagram of blade skin layup;

[0035] Figure 4 Schematic diagram of chopped fiber preform;

[0036] Figure 5 This is a schematic diagram of the root bushing distribution;

[0037] Figure 6 This is a schematic diagram of a typical cross-sectional structure of an integrated two-bladed fixed-pitch propeller airfoil section according to an embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the manufacturing process of an integrated two-bladed fixed-pitch propeller according to an embodiment of the present invention;

[0039] Figure 8 This is a side view of the root connection area of ​​an integral two-bladed fixed-pitch propeller according to an embodiment of the present invention;

[0040] Figure 9 This is a top view of the root connection area of ​​the integrated two-bladed fixed-pitch propeller blade according to an embodiment of the present invention;

[0041] Among them, 1—root, 2—airfoil section, 3—bulb, 4—skin, 5—chopped fiber prefabricated component, 6—foam filling, 7—small beam, 8—reinforcing rib, 9—connecting bolt, 10—cover plate, 11—nut, 12—washer, 13—counterweight support, 14—counterweight plate, 15—rotor shaft. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0044] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0046] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0048] This invention proposes a lightweight, efficient material arrangement, and low-cost integrated two-bladed fixed-pitch propeller and its connecting parts, which abandons the traditional propeller hub structure and meets the needs of vertical take-off and landing aircraft and other aircraft for providing lift or propulsion.

[0049] like Figures 1 to 6 The blade is divided into two parts: the root section 1 and the airfoil section 2. The root section 1 accounts for 10%-20% of the total blade length. Specifically, it consists of a bushing 3, a skin 4, a chopped fiber prefabricated component 5, foam filling 6, a small beam 7, and reinforcing ribs 8.

[0050] like Figures 8 to 9 The blades are connected to the rotor shaft 15 via bushing 3 in the root platform area. The airfoil section 2 provides aerodynamic lift. The airfoil section 2 extends from the root 1 to both sides, forming a combination of two blades with a 180° angle, and has a fixed collective pitch angle.

[0051] The outermost part of the blade root 1 is wrapped with a skin 4 formed of one or more fiber-reinforced composite materials of various specifications. The skin 4 can be made of glass fiber and carbon fiber woven prepreg. The glass fiber woven prepreg is laid on the outermost layer of the skin, with a laying direction of 0 / 90 degrees, and 1-2 layers, to enhance the blade's environmental adaptability and protect the inner skin from erosion by sand, raindrops, etc. The carbon fiber woven prepreg is laid on the inner layer of the skin, with 4-15 layers. Depending on the requirements of blade stiffness, dynamics, and strength, about 30%-50% of the carbon fiber woven prepreg is laid with a laying direction of 0 / 90 degrees to increase the blade's tensile, flapping, and oscillation stiffness and increase the blade's load-bearing capacity; about 50%-70% is laid with a laying direction of ±45 degrees to increase the blade's torsional stiffness and enhance the blade's stability.

[0052] The outer skin 4 of the blade airfoil section 2 extends from the root skin. From the airfoil initiation position to the 0.5R position of the blade, 50%-75% of the inner skin 4 is sequentially cut along the span direction to reduce the number of skin layers in the airfoil section area with lower load and improve material utilization. Cutting occurs approximately every 0.1R, with 1-2 layers cut each time. The cutting angle α is a 45-60 degree oblique cut to minimize the impact of sudden stiffness changes.

[0053] The interior of the blade root 1 is filled with chopped fiber preforms 5 to improve the load-bearing capacity of the blade root and prevent the interior filling from being crushed under high lift. The chopped fiber preforms 5 can be made of glass chopped fiber prepreg or carbon chopped fiber prepreg, etc.

[0054] The bushing 3 at the blade root 1 is integrally formed with the chopped fiber preform 5. The blade is connected to the rotor shaft 15 via the bushing 3 to transmit torque. The pre-embedded positions, number of bushings, and bushing hole sizes can be designed according to the rotor shaft interface, providing excellent interface compatibility. The pre-embedded bushing holes are centered on a circle with the blade rotation center as the center, and the distribution radius should be as large as possible within the blade root platform area to improve torque transmission efficiency.

[0055] The upper and lower end faces of the blade bushing 3 must be 0-0.5mm lower than the surface of the blade root platform area.

[0056] The blade has elongated beams 7 solidified on the inner surfaces of the upper and lower airfoils of the skin 4. Viewed along the projection direction of the upper surface of the blade, the beams are arranged on the centerline of the blade, which can effectively improve the tensile and flapping stiffness of the blade, increase the load-bearing capacity of the blade, and greatly improve the material utilization rate. The beams 7 are made of carbon fiber prepreg unidirectional tape or unidirectional fabric as raw materials, and the width is usually 50% of the blade reference chord length, and the thickness is 1mm-3mm. Different widths and thicknesses can be designed according to stiffness, strength and dynamic requirements.

[0057] The airfoil section 2 of the blade is internally arranged with "C"-shaped reinforcing ribs 8 composed of fiber-reinforced prepreg layers, forming a double-closed or multi-closed-cavity structure with the skin 4, improving the blade's torsional stiffness and load-bearing capacity. Typically, carbon fiber woven prepreg is used as the raw material, with a layup direction of ±45 degrees and 2-6 layers. The number of "C"-shaped reinforcing ribs 8 is 1-3. The number of layup layers and reinforcing ribs can be designed according to stiffness, strength, and dynamic requirements. When the number of reinforcing ribs exceeds 3, the efficiency of increasing the blade's torsional stiffness will significantly decrease. Other areas inside the airfoil section 2 are filled with foam 6 to reduce the blade's weight.

[0058] This invention also provides a method for manufacturing the blade. The blade production process begins by embedding a bushing 3 within a chopped fiber prepreg. The bushing 3 and the chopped fiber preform 5 are then cured and bonded together in a preform mold. Next, the chopped fiber preform 5, foam filler 6, reinforcing ribs 8, etc., are assembled in the blade mold to form an inner core. An outer skin 4 and a beam 7 are then wrapped around the core and cured a second time to form the blade. The curing temperature of the materials used for the blade skin 4, beam 7, and "C"-shaped reinforcing ribs 8 must be lower than the glass transition temperature of the chopped fiber preform 5 to avoid excessively high temperatures during the second curing process, which could degrade the material properties of the chopped fiber preform.

[0059] The blade connector has a small number of parts and a simple structure. Specifically, it consists of connecting bolts 9, a cover plate 10, a nut 11, a washer 12, and counterweights 14. The blade is connected to the rotor shaft 15 via the connector. The cover plate can be designed in a rectangular or circular shape depending on the shape of the blade root platform area. A weight-reducing hole is designed in the center of the cover plate, and the edges of the cover plate have a 1mm-3mm rounded corner. A counterweight support 13 is provided on the top of the blade connecting bolts 9, on which counterweights 14 can be added. This can be used for dynamic balance adjustment of the blades after installation, reducing blade vibration. The counterweights are 0.5-1mm thick, and a maximum of 8-15 counterweights can be placed on the support.

[0060] The present invention will be further illustrated below through specific embodiments:

[0061] Figure 1 The main components of a single-bladed, fixed-pitch blade are shown, consisting of a root section 1 and an airfoil section 2. The root bushing is used for connection to the rotating shaft; the airfoil section 2 extends from the root section 1 to both sides, forming a combination of two blades at a 180° angle, with a fixed collective pitch angle according to aerodynamic efficiency requirements. In this embodiment, considering factors such as power system output, rotational speed, and aerodynamic lift, the blade collective pitch is designed to be 15 degrees, with the root section 0 as the reference and the blade section 0.7R as the collective pitch reference section.

[0062] Figure 2The diagram shows a typical cross-sectional structure of the root section 1 of a two-bladed fixed-pitch rotor blade, externally composed of a skin 4. The skin 4 is made of one or more fiber-reinforced composite materials of various specifications. Compared to the skin of the airfoil section 2, the root skin has more layers, and the spacing between the upper and lower airfoil skins is significantly greater than that of the airfoil section, enhancing the load-bearing capacity of the blade root. In this embodiment, the spacing between the upper and lower airfoil skins at the blade root is 50 mm. The outermost layer of the blade skin 4 is made of one layer of HS6 high-strength glass cloth prepreg, and the inner skin is made of eight layers of T800 carbon cloth prepreg, with 0 / 90 degrees and ±45 degrees each accounting for half. In a typical root cross-section, each additional layer of 0 / 90 degree carbon cloth increases the blade tensile stiffness by approximately 20%, flapping stiffness by approximately 15%, and teeter stiffness by approximately 25%; each additional layer of ±45 degree carbon cloth increases the blade torsional stiffness by approximately 15%.

[0063] Figure 3 A schematic diagram of the 4-ply blade skin cutting is shown. In this embodiment, based on load calculations, the load on the airfoil section is smaller than that on the root section. The centrifugal force, bending moment, and other loads on a typical 0.5R section are more than 60% smaller than those at the blade root. The design uses 8 layers of carbon fiber prepreg within the 0.5R range of the airfoil section, of which 6 layers are cut to improve material utilization and increase blade economy. In this embodiment, the skin cutting angle is 45 degrees to reduce the impact of stiffness variations on the blade.

[0064] Figure 4 The paddle root chopped fiber preform 5 is shown, its shape determined according to the shape of the paddle root cavity. The bushing 3 is assembled with the chopped fiber preform mold, embedded within the chopped fiber prepreg, and cured. In this embodiment, carbon chopped fiber is selected as the raw material.

[0065] Figure 5 The blade root connection area is shown. In this embodiment, four bushings 3 are arranged on a circle with a radius of 100mm centered at the rotation center, and the blades are connected to the rotor shaft through the bushings. The bushing hole diameter is 16mm. Given the allowable stress of the material used for the connecting bolts 9, and based on the magnitude of the transmitted lift, torque, and bending moment, the number of connecting holes, the radius of the distribution circle, and the bushing hole diameter can be calculated using conventional engineering calculations. The upper and lower end faces of the bushings 3 are 0-0.5mm lower than the surface of the blade root platform area to avoid interference with the mounting interface.

[0066] Figure 6 The typical cross-sectional structure of blade airfoil section 2 is shown. In this embodiment, the foam filler 6 uses a density of 52 kg / m³. 3 Polyurethane foam is used as the raw material. The small beam 7 uses unidirectional carbon fiber prepreg tape as the raw material. The typical cross-section of the small beam is 3mm thick and 60mm wide. For every 1mm increase in the thickness of the small beam, the flapping stiffness of the typical blade cross-section can be increased by 30%.

[0067] Figure 6The typical cross-sectional structure of blade airfoil section 2 is shown. In the embodiment, the "C"-shaped reinforcing rib is made of T800 carbon fiber cloth, with a layup direction of ±45 degrees and 4 layers. One reinforcing rib is provided, which together with the skin forms a double closed cavity structure, increasing the torsional stiffness of the typical blade cross-section by about 30%.

[0068] Figure 7 The production process of an integrated two-bladed fixed-pitch propeller blade is shown, which can generally be divided into three parts: material preparation, molding, painting, and static balancing. In this embodiment, the bushing 3 and the chopped fiber preform 5 are first cured and bonded together in a preform mold. Then, the chopped fiber preform 5, foam filler 6, reinforcing ribs 8, etc., are assembled in the blade mold to form the inner core, and the outer casing, including the beam 7 and skin 4, is then cured a second time to form the propeller blade. The carbon fiber prepreg used for the chopped fiber preform 5 has a glass transition temperature of 160°C; the skin 4, beam 7, and reinforcing ribs 8 are made of medium-temperature curing composite materials with a curing temperature of 120°C-130°C; this avoids exceeding the temperature tolerance of the chopped fiber preform 5 during the second curing process, which would reduce its material properties.

[0069] Figure 8 , Figure 9 The diagram illustrates the composition and connection method of the integrated two-bladed fixed-pitch propeller connector. In this embodiment, based on the magnitude of the transmitted lift, torque, and bending moment, and considering conventional engineering calculations and a safety factor, the diameter of the connecting bolt 9 is designed to be 16mm. The counterweight plate 14 is 1mm thick, with each plate weighing approximately 1.5g. Each counterweight support 13 can accommodate a maximum of 10 counterweight plates. The maximum number of counterweight plates that can be installed and the weight of each plate can be calculated based on data such as the allowable weight deviation of a single blade, the allowable center-of-gravity deviation of the blade, and the distance between the counterweight support and the center of rotation.

[0070] The integrated two-bladed fixed-pitch blade of this invention has a skin composed of single or small quantities of fiber-woven prepreg. Glass fiber woven prepreg is laid on the outermost layer of the blade, enhancing its environmental adaptability and protecting the inner skin from erosion by sand, raindrops, etc. Carbon fiber woven prepreg is laid on the inner layer of the skin, with a certain proportion of 0 / 90 degree and ±45 degree layups, increasing the blade's tensile, flapping, and tessellation stiffness, as well as its torsional stiffness. This increases both the blade's load-bearing capacity and stability, preventing flutter or other aeroelastic coupling instabilities. From the airfoil initiation position to the 0.5R position of the blade, most of the inner skin is sequentially cut along the span, effectively increasing the load-bearing capacity of the blade root and the heavily loaded areas at the airfoil initiation section, while also minimizing blade weight, improving composite material utilization, and reducing blade cost.

[0071] The skin cutting angle is usually 45-60 degrees oblique cutting. Compared with the conventional 0-degree straight cutting along the chord length, it can effectively reduce the impact of the stiffness change caused by the skin cutting on the blade and avoid stress concentration.

[0072] The root of the integrated two-bladed fixed-pitch blade proposed in this invention is filled with short fiber preforms made of raw materials such as glass short fiber prepreg or carbon short fiber prepreg, which can improve the load-bearing capacity of the blade root and prevent the filling inside the root from being crushed under high lift.

[0073] The integrated two-bladed fixed-pitch rotor blade proposed in this invention is connected to the rotor shaft via a root bushing. The bushing is pre-embedded within a chopped fiber preform and is cured integrally with the preform. Compared to the common root-drilling and bushing-embedding method, this approach avoids damage such as skin delamination during the drilling process. Furthermore, the bushing and blade body are more tightly integrated, resulting in a more stable structure and preventing fretting wear between the bushing and the blade body.

[0074] This application combines the bushing with the chopped fiber preform and places it at the blade root. Its function is not only to avoid drilling later, but also to effectively transfer and disperse the complex multi-directional loads (centrifugal force, flapping moment, oscillation moment, etc.) at the root by utilizing the isotropic properties of the chopped fiber preform, and to prevent the root from being crushed under huge loads.

[0075] Unlike continuous fiber preforms, chopped fiber preforms, although continuous fiber braided structures have continuity, their fiber orientation is obvious when subjected to complex multi-directional loads, and they may not be able to achieve uniform load diffusion like chopped fiber preforms.

[0076] This application organically integrates four major technical features: a symmetrical layout of one body and two blades, a root reinforcement structure of embedded bushings and chopped fiber prefabricated components, spanwise spars located on the centerlines of the upper and lower blade surfaces, and C-shaped reinforcing ribs forming a closed cavity with the skin. This integration is not a simple superposition, but rather produces a series of synergistic effects: the one body and two blades structure simplifies the connection and reduces weight; the embedded bushing root structure provides a reliable and efficient load transfer path; the spanwise spars precisely enhance tensile and flapping stiffness and control deformation; and the C-shaped reinforcing ribs forming a closed cavity with the skin significantly improve torsional stiffness. These four features work together to enable the blades of this application to possess excellent load-bearing capacity, stiffness characteristics, and reliability while maintaining an extremely simplified overall structure, perfectly achieving the design goals of "lightweight, simple structure, reliable structure, and low cost."

[0077] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A single-bladed, fixed-pitch propeller blade, characterized in that, include: The blade consists of two integrated blades arranged at a 180° angle. The blade root includes a bushing and a chopped fiber preform that are solidified into one piece. The blade is connected to the rotor shaft through the bushing. The outermost part of the blade root is covered by a skin made of fiber-reinforced composite material. The skin covering the blade airfoil section extends from the root skin. The blade has long strip-shaped beams arranged along the blade centerline solidified on the inner surface of the upper and lower airfoil surfaces. The blade airfoil section has at least one "C"-shaped reinforcing rib arranged inside, forming a double-closed or multi-closed cavity structure with the skin. Other areas inside the airfoil section are filled with foam.

2. The integrated two-bladed fixed-pitch propeller according to claim 1, characterized in that, From the starting position of the airfoil section to the 0.5R position of the blade, 50%-75% of the inner skin is cut sequentially along the span direction; the remaining layers are laid up to the blade tip.

3. The integrated two-bladed fixed-pitch blade according to claim 2, characterized in that, The specific cutting process is as follows: cut once every 0.1R, cutting 1-2 layers each time, with a cutting angle α of 45-60 degrees for bias cutting.

4. The integrated two-bladed fixed-pitch propeller according to claim 1, characterized in that, The reinforcing ribs are formed by fiber-reinforced prepreg layers.

5. The integrated two-bladed fixed-pitch propeller according to claim 1, characterized in that, The skin is made of woven prepreg fabric of glass fiber and carbon fiber.

6. The integrated two-bladed fixed-pitch propeller according to claim 5, characterized in that, Fiberglass woven prepreg is laid on the outermost layer of the skin, with a laying direction of 0 / 90 degrees and 1-2 layers. Carbon fiber woven prepreg is laid on the inner layer of the skin, with 4-15 layers.

7. The integrated two-bladed fixed-pitch propeller according to claim 6, characterized in that, The proportion of carbon fiber woven prepreg is 30%-50% with the laying direction at 0 / 90 degrees, and 50%-70% with the laying direction at ±45 degrees.

8. The integrated two-bladed fixed-pitch propeller according to claim 1, characterized in that, The chopped fiber preforms are made of glass chopped fiber prepreg or carbon chopped fiber prepreg.

9. The integrated two-bladed fixed-pitch propeller according to claim 1, characterized in that, The upper and lower end faces of the blade bushing should be 0-0.5mm lower than the surface of the blade root platform area.

10. The integrated two-bladed fixed-pitch blade according to claim 1, characterized in that, The beams are made of prepreg carbon fiber unidirectional tape or unidirectional fabric.

11. The integrated two-bladed fixed-pitch blade according to claim 1, characterized in that, The width of the spar is 50% of the blade reference chord length, and the thickness is 1mm-3mm.

12. The integrated two-bladed fixed-pitch blade according to claim 1, characterized in that, The reinforcing ribs are made of carbon fiber woven prepreg with a layup direction of ±45 degrees and 2-6 layers.

13. A method for processing an integral two-bladed fixed-pitch propeller blade as described in any one of claims 1-12, characterized in that, include: Step 1: Embed the bushing in the chopped fiber prepreg, and pre-cure the bushing and chopped fiber prepreg together in the preform mold to form the root preform; Step 2: Lay the skin inside the blade mold and place the beam on the skin surface; Step 3: Then assemble the root prefabricated part, front and rear cavity foam, and reinforcing ribs to form the inner core; Step 4: Position the inner core in the blade mold that has been covered with skin and beams, and after the mold is closed, it is cured twice to form the blade.

14. The processing method according to claim 13, characterized in that, The secondary curing temperature is lower than the glass transition temperature of the chopped fiber preform.

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