Trapezoidal-configuration flying-wing-layout tilt-rotor aircraft

Abstract

The invention discloses a trapezoidal-configuration flying wing layout tilting rotor aircraft, which belongs to the technical field of aviation and comprises a fuselage, flying wing type wings, tilting mechanisms, driving parts and four rotors. The tilting mechanism comprises an arm assembly and a tilting driving assembly, a first pipe and a second pipe of the arm assembly are fixed to the wing tip and the wing root of the wing respectively, and the tilting driving assembly drives the rotor wings to tilt synchronously. In an initial state, a rotor rotating shaft is perpendicular to the horizontal plane, and a rotating sweeping surface is not overlapped with the fuselage and the wings, so that interference of lower washing flow of the rotors on the wings is reduced; in the level flight state, rotating shafts of the rotors are parallel to the horizontal plane, the four rotors are distributed in a trapezoid shape with the front portion wide and the rear portion narrow in the overlook direction, the rotary sweeping face of the front side rotor completely covers the wingtip, and the rotary sweeping face of the rear side rotor is mainly located on the upper surface of the wing. The aerodynamic interference between the front rotor wing and the rear rotor wing is reduced from the layout level, the thrust efficiency of the rear rotor wing is improved, and the lift-drag ratio and the cruising ability of the whole machine are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aviation technology, and particularly relates to a trapezoidal configuration flying wing layout tilt-rotor aircraft. BACKGROUND

[0002] The tilt-rotor aircraft is a new concept and configuration aircraft, which can effectively combine the advantages of fixed-wing aircraft and rotor aircraft, and has the capabilities of high-speed cruising, vertical take-off and landing and air hovering. Its flight envelope basically covers the typical flight states of fixed-wing aircraft and rotor aircraft. After more than 20 years of development, tilt-rotor aircrafts are mainly divided into tilt-rotor two-rotor, tilt-rotor three-rotor and tilt-rotor four-rotor according to the number of rotors. Among them, the tilt-rotor two-rotor aircrafts are V-22 and V-280 of the United States, the tilt-rotor three-rotor aircrafts are the Israeli "Black Panther" and the German Trinity F90, and the tilt-rotor four-rotor aircrafts are the Chinese "Blue Whale" and the Canadian Aquafly.

[0003] In the existing configuration, the tilt-rotor four-rotor aircraft with symmetrical layout is a common and mature configuration form. Compared with the tilt-rotor two-rotor and tilt-rotor three-rotor, the tilt-rotor four-rotor has stronger control redundancy and fault tolerance, and can realize longer range and time in the cruising stage. The existing tilt-rotor four-rotor aircraft is usually composed of a four-rotor system and a fixed-wing system. The four-rotor part is mostly in X configuration, which has mature control technology, outstanding stability and easy controllability; the fixed-wing part mostly adopts the conventional layout, which is widely used because of its mature technology.

[0004] In recent years, some researchers have tried to introduce the flying wing layout into the tilt-rotor four-rotor aircraft. Compared with the conventional layout, the flying wing layout has the advantages of light structure weight, high aerodynamic efficiency and large internal volume. The introduction of this layout form has promoted the development of tilt-rotor four-rotor aircraft to some extent. However, during the cruising flight of the X-configuration tilt-rotor four-rotor aircraft, there is generally aerodynamic interference between the front and rear rotors. The downwash flow and induced flow field generated by the front rotor change the inflow conditions of the rear rotor, resulting in a decrease in the thrust efficiency of the rear rotor, and thus affecting the endurance and lift-drag ratio of the whole machine.

[0005] In-depth analysis shows that the essential reason for the interference between the front and rear rotors is that the induced flow field of the front rotor causes uneven inflow velocity distribution of the rear rotor, which changes the local angle of attack of the rear rotor blades, even causes local stall or uneven load distribution, and finally causes a decrease in thrust efficiency. This problem is particularly prominent in low-altitude economic application scenarios such as logistics distribution, manned transportation and emergency rescue, and needs to be improved from the aspects of rotor layout and aerodynamic design.

[0006] The patent CN120440328A mainly aims at the problem that the performance of the existing countermeasure carrier UAV is single and it is difficult to balance high-speed cruising and stable tracking. The patent designs a tilt four-rotor UAV platform that combines the advantages of fixed-wing and multi-rotor, the wing tip of which is provided with a pod that can be tilted synchronously, and the pod is internally provided with a rotor and a winglet, so that the UAV can quickly approach the target by tilting to horizontal to enter the high-speed cruising mode, and also can hover and take off vertically by tilting to vertical, thereby realizing stable tracking and aiming at close range. A tracking algorithm combined with filtering and prediction and a control strategy for adjusting the flight mode and attitude in real time according to the distance and speed difference are adopted. However, the above technical problems have not been effectively solved.

[0007] The core of the patent CN119408766A lies in a tilt mechanism with simplified structure and without additional steering engine driving. The tilt mechanism generates a tilt torque by controlling the lift difference between the front and rear rotor groups, thereby driving the entire rotor group to tilt. A transmission system including a spur gear and a bevel gear is innovatively adopted, so that the support frame only needs to rotate a small angle to drive the rotor to complete a large-angle attitude conversion, thereby realizing the switching between vertical take-off and horizontal propulsion modes while greatly reducing the space and mechanical complexity required in the tilt process. Overall, the scheme achieves the purposes of simplifying the structure, improving the reliability and reducing the manufacturing cost by means of the ingenious pure mechanical transmission design under the premise of ensuring the tilt function. However, the above technical problems have not been effectively solved. SUMMARY

[0008] In view of the problem that the aerodynamic interference between the front and rear rotors of the existing X-shaped tilt four-rotor aircraft is obvious and the thrust efficiency of the rear rotor is reduced during the cruising stage, the present application proposes a trapezoidal configuration flying wing layout tilt rotor aircraft, which significantly reduces the aerodynamic interference between the front and rear rotors and improves the thrust efficiency of the rear rotor through the coordinated design of the spatial layout and rotation direction of the rotors, thereby improving the lift-drag ratio and endurance of the whole machine.

[0009] To achieve the above application purposes, the present application provides the following technical solutions: A trapezoidal configuration flying wing layout tilt rotor aircraft, comprising a fuselage, a flying wing, a tilt mechanism, a driving member and rotors, the tilt mechanism being connected with the wing, the driving member being installed on the tilt mechanism, and the rotors being respectively installed on the output ends of the driving members, the tilt mechanism being a core component for realizing the tilt of the rotors and comprising a boom assembly and a tilt driving assembly, wherein the boom assembly is used for connecting the wing and the tilt driving assembly and comprises mounting members fixed at the wing tips and wing roots respectively, the tilt driving assembly is connected with the mounting members and can drive the driving members and the rotors to tilt synchronously, thereby realizing the switching of the flight mode.

[0010] The rotation axes of the rotors are perpendicular to the horizontal plane in the initial state, and the rotation sweep surfaces are in the same horizontal plane and do not overlap with the fuselage and the wings, so that the downwash generated by the rotors has less interference with the wings, and additional resistance for vertical take-off and landing is avoided; in the level flight state, the rotation axes of the rotors are parallel to the horizontal plane, and the rotors are distributed in a trapezoidal shape with a wide front side and a narrow rear side, the rotation sweep surface of the front rotors completely covers the wing tips, and the rotation sweep surface of the rear rotors is mainly located on the upper surface of the wings, so that the interference between the rotors is fundamentally reduced through layout optimization, and most of the area of the rotation sweep surface of the rear rotors covers the upper surface of the wings and is not less than 90%, so that the rear rotors can fully promote the airflow on the upper surface of the wings.

[0011] As preferred, the tilting driving assembly comprises a U-shaped movable piece, a steering engine and a U-shaped fixed piece, the steering engine is used as a power source, one end of the steering engine is fixedly connected with the U-shaped fixed piece, the other end of the steering engine is drivingly connected with the U-shaped movable piece, the driving member is fixedly installed on the U-shaped movable piece, the U-shaped fixed piece is connected with the mounting member, the U-shaped movable piece is driven to rotate by the steering engine, so that the front rotors are tilted forward and the rear rotors are tilted backward synchronously, and the switching between vertical take-off and level flight modes is stably completed.

[0012] As preferred, the mounting member comprises a first pipe, a second pipe, an O-shaped connecting clamp, a side plate and a support piece, the first pipe is fixed at the wing tip, the second pipe is fixed at the wing root, the O-shaped connecting clamp is fixed with the first pipe and the second pipe respectively, the side edges of the O-shaped connecting clamp are connected with the side plate, the end of the side plate away from the O-shaped connecting clamp is fixedly connected with the support piece, and the support piece is connected with the U-shaped fixed piece, the sequential connection of the components ensures the stability and reliability of the connection between the tilting mechanism and the wings, and provides structural guarantee for stable tilting of the rotors.

[0013] As preferred, the first pipe and the second pipe are made of carbon fiber material, and the tensile strength of the carbon fiber material is greater than 3400 MPa, so that the carbon fiber material can ensure the structural strength and realize lightweight design, and meet the demand of weight reduction of the aircraft; after the second pipe is installed, the rear rotors can work without interference with the wings and adjacent rotors, and after the first pipe is installed, the rotation sweep surface of the front rotors can completely cover the wing tips, so that the front rotors can further suppress the strength of the wing tip induced vortex and reduce the induced drag.

[0014] As preferred, in the flat flight state, the front rotor rotates outwardly toward the wing tip direction, opposite to the direction of the wing tip vortex, which can effectively inhibit the wing tip vortex flowing toward the wing span direction and weaken the influence of the wing tip vortex, and the rear rotor rotates inwardly toward the body symmetry axis direction, and the low pressure area generated in front of the rear rotor can promote the flow velocity on the upper surface of the wing to delay the airflow separation of the whole machine, and the distance between the rotation axes of the adjacent rotors in the wing span direction is greater than the equivalent diameter of the rotation sweep surface of the rotors, so that the slip stream generated by the front rotor cannot affect the rear rotor, and the thrust efficiency of the rear rotor is significantly improved.

[0015] As preferred, the rotors are of the same structure, and the rotation directions of the adjacent rotors are opposite during operation, and the rotation directions of the rotors arranged at opposite angles are the same, wherein the adjacent rotors refer to the rotors with a relatively short distance, and the rotors on the opposite sides of the trapezoidal rotor group are the non-adjacent rotors, and the rotation direction design ensures the attitude stability and easy controllability during flight of the aircraft.

[0016] As preferred, the rotation range of the rotors is 0-90°, wherein 0° corresponds to the vertical take-off and landing and hovering state, at this time, the hovering function can be realized by controlling the rotation speed of the rotors, and 90° corresponds to the flat flight state, at this time, the rotors provide forward thrust, and the wings provide lift; if the wings have an upward angle, the rotation axis of the rotor in the initial state can be kept perpendicular to the horizontal plane by adjusting the tilt driving assembly, so as to avoid the adverse effects of installation errors on the flight performance.

[0017] As preferred, the body and the wing are of a structure in which a frame is wrapped with a skin, under the condition of ensuring the aerodynamic shape and the structural rigidity and strength, the design principle of as light as possible is followed, the endurance of the aircraft is further optimized, and the aircraft is more in line with the actual application requirements.

[0018] As preferred, the aircraft is of a left-right symmetrical structure, the symmetrical layout is not only beneficial to the stable control of the flight attitude, but also can make the downwash flow generated by the rotors during the vertical take-off interfere less with the wings, and further improve the thrust efficiency.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1. The front and rear rotor interference problem of the X-shaped tilt four-rotor aircraft is significantly reduced from the layout level by the multiple designs such as the trapezoidal rotor layout, the outward rotation of the front rotor covering the wing tip, the inward rotation of the rear rotor arranged on the upper surface of the wing, and the reasonable setting of the rotor spacing, the thrust efficiency of the rear rotor is significantly improved, and the lift-drag ratio and the endurance of the whole machine are greatly improved; 2. The aircraft has the functions of vertical take-off, air hovering and rapid cruising, the thrust efficiency is high during the vertical take-off, the hovering stability is good, the flat flight speed and the range are outstanding, and the flight envelope of the fixed-wing and rotor aircraft is covered. 3. Adopting the flying wing layout and the frame outer package skin structure, cooperating with the first pipe, the second pipe and the brushless DC motor of carbon fiber material, realizing the light weight under the premise of guaranteeing the structural strength, rigidity and aerodynamic performance, further optimizing the endurance; 4. The dihedral angle on the wing can be adjusted through the adjustment of the tilting driving assembly, the influence of the installation error on the flight performance is avoided, the left-right symmetrical structure design ensures the stable flight attitude, and the easy controllability is outstanding; 5. It is suitable for low-altitude economic fields such as logistics distribution, manned transportation and emergency rescue, can meet the flight requirements in different scenes, and has high practicality and popularization value. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 It is a vertical take-off and landing state structure schematic diagram of the tilt-rotor aircraft in the embodiment of the present application; Figure 2 It is a horizontal flight state structure schematic diagram of the tilt-rotor aircraft in the embodiment of the present application; Figure 3 It is a vertical take-off and landing state top view of the tilt-rotor aircraft in the embodiment of the present application; Figure 4 It is a first kind of structure schematic diagram of the tilting mechanism in the embodiment of the present application; Figure 5 It is a second kind of structure schematic diagram of the tilting mechanism in the embodiment of the present application; In the figure: 1-body, 2-wing, 3-U-shaped movable piece, 4-rudder, 5-U-shaped fixed piece, 6-first pipe, 7-second pipe, 8-O-shaped connecting clamp, 9-side plate, 10-supporting piece, 11-motor, 12-first front rotor, 13-second front rotor, 14-first rear rotor, 15-second rear rotor, 16-elevon, A-wing root, B-wing tip. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] Please refer toFigures 1-5 The embodiment provides a trapezoidal configuration flying wing layout tilt-rotor aircraft, which is left-right symmetrical structure as a whole. The symmetrical layout as a high-level concept is embodied in that the fuselage 1, the wing 2 and the mounting positions of each rotor and tilt mechanism are symmetrically distributed with the symmetry axis of the fuselage 1 as the center, which can effectively ensure the attitude stability in the flight process and reduce the asymmetric interference of airflow on the aircraft. The fuselage 1 and the wing 2 of the aircraft adopt a structure form that a frame is wrapped with a skin. The structure design can meet the requirements of aerodynamic shape, structural rigidity and strength. In specific implementation, the frame is built by using high-strength lightweight material, and the skin is tightly wrapped outside the frame to form a continuous, smooth and complete aerodynamic shape, which meets the structural bearing requirements and provides a guarantee for lightweight design and lays a foundation for improving the endurance capability.

[0024] The core executive component of the aircraft is the tilt mechanism, which as a high-level concept core function drives the rotor to realize 0-90° tilt and then completes the flight mode switching. The tilt mechanism specifically includes a boom assembly and a tilt driving assembly. The boom assembly is used to connect the wing 2 and the tilt driving assembly and includes a first pipe 6, a second pipe 7, an O-shaped connecting clamp 8, a side plate 9 and a support sheet 10. The first pipe 6 is fixed at the wing tip B of the wing 2, and the second pipe 7 is fixed at the wing root A of the wing 2. Both of them are made of carbon fiber material and have a tensile strength greater than 3400 MPa. The selection of the carbon fiber material not only ensures the structural strength of the pipe but also meets the design requirements of the lightweight aircraft. After installation of the first pipe 6, the rotating swept surface of the first front rotor 12 and the second front rotor 13 can completely cover the wing tip B. After installation of the second pipe 7, the first rear rotor 14 and the second rear rotor 15 can work without interference with the wing 2 and the adjacent rotors. At the same time, the rotating swept surface of the first rear rotor 14 and the second rear rotor 15 in the level flight state is ensured to be greater than 90% of the area located on the upper surface of the wing 2, which fully plays a promoting role on the airflow of the upper surface of the wing. The O-shaped connecting clamp 8 is fixedly connected with the first pipe 6 and the second pipe 7, and the side edge thereof is tightly connected with the side plate 9. The end of the side plate 9 away from the O-shaped connecting clamp 8 is fixed with the support sheet 10, and the support sheet 10 is connected with the U-shaped fixed sheet 5. The sequential fixation of the components forms a stable boom assembly, which provides a reliable installation basis for the tilt driving assembly. The tilt driving assembly includes a U-shaped movable sheet 3, a steering wheel 4 and a U-shaped fixed sheet 5. The steering wheel 4 as a power output component is fixedly connected with the U-shaped fixed sheet 5 at one end and is in transmission connection with the U-shaped movable sheet 3 at the other end. The driving part, i.e. the brushless DC motor 11, is fixedly installed on the U-shaped movable sheet 3. The brushless DC motor 11 as a driving part has the characteristics of brushless structure. The first front rotor 12, the second front rotor 13, the first rear rotor 14 and the second rear rotor 15 are respectively installed at the output end of the corresponding brushless DC motor 11. The four rotor structures are the same, which facilitates production, maintenance and replacement.

[0025] During the installation process, after the assembly of the arm assembly and the tilting drive assembly is completed, the initial state of the rotor needs to be adjusted. If the wing 2 has an upward angle, the installation angle of the U-shaped movable piece 3 can be adjusted to ensure that the rotation axes of the four rotors are perpendicular to the horizontal plane in the initial state, avoiding the influence of installation errors on flight performance. At this time, the rotors are at a 0° tilting angle, corresponding to the vertical take-off mode. Figure 3 As can be seen from the vertical take-off plan view of the figure, the rotation sweep surfaces of the four rotors are in the same horizontal plane and do not overlap with the fuselage 1 and the wing 2. Such a design can ensure that the downwash generated by the rotors does not interfere with the wing 2 and does not increase the additional vertical take-off resistance. Meanwhile, the rotation directions of the adjacent two rotors are opposite, and the rotation directions of the opposite two rotors are the same. Here, the adjacent rotors refer to the rotors with a relatively short distance. In the trapezoidal distribution of the four rotors, the two rotors on the diagonal are the most distant and are not adjacent. Specifically, the first front rotor 12 and the first rear rotor 14, the second front rotor 13 and the second rear rotor 15 are adjacent rotors with opposite rotation directions, and the first front rotor 12 and the second front rotor 13, the first rear rotor 14 and the second rear rotor 15 are diagonal rotors with the same rotation direction. Such a rotation direction setting can effectively offset the counter-torque generated by the rotation of the rotors, ensuring the stability of the vertical take-off process. After starting the brushless DC motor 11, the four rotors rotate synchronously. By adjusting the motor speed, the total thrust is greater than the total weight of the aircraft, and the aircraft can vertically ascend. During the ascending process, the interference of the rotor downwash on the wing 2 is small, and the thrust efficiency is high. When vertically landing, the motor speed is gradually reduced to reduce the total thrust, so that the aircraft slowly descends. When approaching the ground, the total thrust is adjusted to balance the total weight of the aircraft, realizing smooth landing.

[0026] The working principle of the application is as follows: during the vertical take-off stage, the rotation axis of the rotor is perpendicular to the horizontal plane, i.e. 0° tilting, and the four rotors provide upward thrust. Since the rotor rotation sweep surface does not overlap with the fuselage and the wing, the downwash interference on the wing is small, ensuring the stability and efficiency of the vertical take-off; during the hovering stage, the total thrust is balanced with the total weight of the aircraft by precisely controlling the rotation speed of the four rotors in the vertical take-off mode, realizing air hovering; during the level flight stage, the steering engine drives the U-shaped movable piece to gradually rotate, driving the front rotors to tilt forward and the rear rotors to tilt backward until the rotation axis of the rotor is parallel to the horizontal plane, i.e. 90° tilting. At this time, the rotors provide forward thrust, and the wing provides lift, and the aircraft enters the level flight state; during the level flight process, the trapezoidal distribution of the rotors, the specific rotation direction design and the reasonable spacing setting effectively reduce the interference problem of the front and rear rotors, and suppress the wingtip induced vortex intensity, thereby reducing the induced drag, delaying airflow separation, and significantly improving the overall lift-drag ratio and endurance.

[0027] When hovering is needed, on the basis of the vertical take-off and landing mode, the total thrust generated by the four rotors is balanced with the total weight of the aircraft by precisely controlling the rotating speed of the brushless DC motor 11, so that the aircraft can hover in the air. If the attitude deviates due to external interference during hovering, the rotating speed of the corresponding rotor can be adjusted to correct the deviation. Thanks to the symmetrical layout and reasonable rotating direction of the rotors, the hovering stability is excellent.

[0028] The control mode of the aircraft in the vertical take-off and landing and hovering state is as follows: Pitch control: the pitch moment is generated by the thrust difference between the first front rotor 12, the second front rotor 13 and the first rear rotor 14, the second rear rotor 15. Specifically, when the thrust of the first front rotor 12 and the second front rotor 13 increases and the thrust of the first rear rotor 14 and the second rear rotor 15 decreases, the pitch moment upward is generated. When the thrust of the first front rotor 12 and the second front rotor 13 decreases and the thrust of the first rear rotor 14 and the second rear rotor 15 increases, the pitch moment downward is generated. Since the first front rotor 12 and the second front rotor 13 have a longer force arm relative to the center of gravity, the pitch moment generated by the change of the thrust thereof is greater than that of the first rear rotor 14 and the second rear rotor 15. Therefore, under the same pitch control command, the adjustment range of the thrust of the front rotors is smaller than that of the first rear rotor 14 and the second rear rotor 15, so as to avoid over-control.

[0029] Roll control: the roll moment is generated by the thrust difference between the left rotors (the first front rotor 12 and the first rear rotor 14) and the right rotors (the second front rotor 13 and the second rear rotor 15). Specifically, when the thrust of the left rotors increases and the thrust of the right rotors decreases, the moment for left roll is generated. When the thrust of the left rotors decreases and the thrust of the right rotors increases, the moment for right roll is generated. In the trapezoidal configuration, the first front rotor 12 and the second front rotor 13 usually have a larger lateral force arm, and the first rear rotor 14 and the second rear rotor 15 have a smaller lateral force arm. Therefore, the roll control is mainly contributed by the first front rotor 12 and the second front rotor 13, and the first rear rotor 14 and the second rear rotor 15 play an auxiliary role. The control system needs to set the weight differently according to the size of the rotor lateral force arm.

[0030] Yaw control: the imbalance of the rotor counter-torque is used to realize the yaw control. Specifically, when the rotating speed of the first front rotor 12 and the first rear rotor 14 increases and the rotating speed of the second front rotor 13 and the second rear rotor 15 decreases, the aircraft right yaw is generated. When the rotating speed of the first front rotor 12 and the first rear rotor 14 decreases and the rotating speed of the second front rotor 13 and the second rear rotor 15 increases, the aircraft left yaw is generated.

[0031] When switching to the horizontal flight mode, the U-shaped movable piece 3 is driven to rotate by the steering engine 4, the first front rotor 12 and the second front rotor 13 are driven to tilt forward, and the first rear rotor 14 and the second rear rotor 15 are driven to tilt backward. The tilting process is synchronous, until the rotor rotating shaft is parallel to the horizontal plane, that is, the tilt angle reaches 90°, and the flight mode switching is completed. In the horizontal flight state, the four rotors are in a trapezoidal distribution with the front wide and the rear narrow. As a core feature of the upper concept, the trapezoidal layout is specifically embodied in that the distance between the first front rotor 12 and the second front rotor 13 in the wingspan direction is greater than the distance between the first rear rotor 14 and the second rear rotor 15, and the trapezoidal shape is presented in the front wide and the rear narrow from the perspective. The first front rotor 12 and the second front rotor 13 rotate outward toward the wing tip B direction, which is opposite to the direction of the wing tip vortex, and can effectively inhibit the wing tip vortex flowing in the wingspan direction, thereby reducing the influence of the wing tip vortex on the wing 2. The first rear rotor 14 and the second rear rotor 15 rotate inward toward the symmetry axis of the fuselage 1, and the rotating swept surface of more than 90% of the area is located on the upper surface of the wing 2. The low pressure area in the front can promote the flow velocity on the upper surface of the wing 2 to delay the airflow separation of the whole machine. At the same time, the distance between the rotating shafts of the adjacent two rotors in the wingspan direction is greater than the equivalent diameter of the rotor rotating swept surface, which ensures that the slip stream generated by the first front rotor 12 and the second front rotor 13 will not affect the first rear rotor 14 and the second rear rotor 15, thereby significantly improving the thrust efficiency of the rear rotor and the lift-drag ratio and endurance of the whole machine. In the horizontal flight process, the rotors provide forward thrust, and the wing 2 provides lift to drive the aircraft to cruise rapidly, which fully combines the advantages of high-speed cruise of fixed-wing aircraft and vertical take-off and landing of rotor aircraft.

[0032] In the horizontal flight state, the lift of the aircraft is mainly provided by the wing 2 in the flying wing layout, and the control characteristics are similar to those of the traditional fixed-wing aircraft. However, due to the flying wing layout, there is no horizontal tail, and the attitude adjustment needs to rely on the control surfaces of the wing 2: Pitch control: mainly realized by the symmetrical deflection of the elevators 16 of the wing 2. When the left and right elevators are simultaneously upward deflected, the nose is upward. When the left and right elevators are simultaneously downward deflected, the nose is downward.

[0033] Roll control: mainly realized by the differential deflection of the elevators 16 of the wing 2. When the left elevator is upward deflected and the right elevator is downward deflected, the aircraft rolls to the left. When the left elevator is downward deflected and the right elevator is upward deflected, the aircraft rolls to the right, completing the roll maneuver.

[0034] Yaw control: mainly realized by the differential thrust of the rotors. When the rotating speed of the first front rotor 12 and the second rear rotor 15 increases and the rotating speed of the second front rotor 13 and the first rear rotor 14 decreases, the aircraft yaw to the right. When the rotating speed of the first front rotor 12 and the second rear rotor 15 decreases and the rotating speed of the second front rotor 13 and the first rear rotor 14 increases, the aircraft yaw to the left.

[0035] During the transition from the vertical take-off mode to the flat flight mode or vice versa, the U-shaped movable piece 3 drives the rotors to gradually tilt, and the rotation speed of the brushless DC motor 11 is synchronously adjusted, so that the attitude of the aircraft is stable during the transition process, and there is no sudden change in pitch, roll or yaw, the switching process is safe and reliable, and the whole aircraft is effectively reduced through the organic combination of structural design and layout optimization of the technical problems of interference between the front and rear rotors of the existing X-shaped tilt four-rotor aircraft, and has the functions of vertical take-off, hovering and rapid flat flight, and is suitable for various low-altitude economic fields such as logistics distribution, manned transportation and emergency rescue.

[0036] The trapezoidal configuration flying wing layout tilt rotor aircraft has reasonable layout, four rotors are synchronously tilted, the rotors are arranged at the two sides of the wing tip and the two sides of the wing root respectively, are tilted through the rudder driving U-shaped movable piece, and can realize the functions of vertical take-off, hovering and rapid flat flight of the aircraft. When vertically taking off, the rotors provide upward thrust, the downwash of the rotors has little effect on the wings, and the vertical take-off thrust efficiency is high; when hovering is needed, the rotation speed of the rotors is controlled when the aircraft is in the vertical take-off mode; when flat flight is needed, the rudder drives the U-shaped piece to drive the four rotors to synchronously gradually tilt, the rotors provide thrust, and the wings and the fuselage provide lift. In the flat flight state, the front rotors located at the wing tips can effectively inhibit the wing tip vortex flowing towards the wing span direction and weaken the influence of the wing tip vortex flow due to the opposite rotation direction of the wing tip vortex, thereby improving the lift-drag ratio and endurance capacity of the whole machine; the rear rotors located at the wing roots need to satisfy the moment balance of the single wing, and the rotation direction needs to be opposite to that of the wing tip rotors, and when the rear rotors rotate, a low-pressure area is formed on the upper surface of the wing and the flow velocity increases, which can effectively inhibit the backflow of the airflow on the lower surface of the wing to the upper surface to cause airflow separation, thereby effectively increasing the critical angle of attack of the whole machine and improving the lift-drag ratio and endurance capacity of the whole machine. When the aircraft vertically takes off, the downwash of the front and rear rotors has little interference on the wings, and the rotor thrust efficiency is high.

[0037] The application aims at relieving the problem of thrust loss of rear rotor caused by interference of front and rear rotors of X configuration tilt four-rotor aircraft, and improving aerodynamic performance to improve endurance and lift-drag ratio of the aircraft, specifically, the traditional X configuration tilt four-rotor is improved, a trapezoidal configuration rotor layout type is proposed, and the flying wing layout is introduced into the tilt four-rotor, when the aircraft is in forward flight state, the front rotor is offset to the wing tip direction by a distance, to ensure that the wing tip is completely in the rotor disc area, the rotation direction of the front rotor rotates outward toward the wing tip, which is opposite to the direction of the wing tip vortex, and the interference of the slipstream generated by the front rotor on the thrust of the rear rotor is reduced, so as to significantly improve the thrust efficiency of the rear rotor, the rear rotor is moved to the upper surface of the wing, to ensure that most of the disc area is on the upper surface of the wing during the process of the aircraft in level flight, the rotation direction of the rear rotor rotates toward the fuselage symmetry axis, and the low pressure area generated in front of the rear rotor is used to accelerate the flow velocity on the upper surface of the wing, to delay the airflow separation of the whole machine.

[0038] The above is only a specific embodiment of the application, but the protection scope of the application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered in the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A trapezoidal flying wing tiltrotor aircraft, characterized in that, Includes fuselage (1), flying wing (2), tilting mechanism, drive components and rotor; The tilting mechanism is connected to the wing (2), the drive component is mounted on the tilting mechanism, and the rotors are respectively mounted on the output end of the drive component; the tilting mechanism includes an arm assembly and a tilting drive assembly, the arm assembly includes mounting components respectively fixed at the wingtip (B) and wing root (A) of the wing (2), and the tilting drive assembly is connected to the mounting components and can drive the drive component and rotors to tilt synchronously; In the initial state, the rotation axes of the rotors are all perpendicular to the horizontal plane, and the rotating sweep surfaces are on the same horizontal plane and do not overlap with the fuselage (1) and the wing (2); In level flight, the rotor's rotation axis is parallel to the horizontal plane, and the rotor is distributed in a trapezoidal shape that is wider at the front and narrower at the rear. The rotating sweep surface of the front rotor completely covers the wingtip (B), and the rotating sweep surface of the rear rotor is mainly located on the upper surface of the wing (2).

2. The trapezoidal flying wing tiltrotor aircraft according to claim 1, characterized in that, In level flight, at least 90% of the area of ​​the rear rotor's sweeping surface is located on the upper surface of the wing (2).

3. The trapezoidal flying wing tiltrotor aircraft according to claim 1, characterized in that, The tilt drive assembly includes a U-shaped movable plate (3), a servo motor (4) and a U-shaped fixed plate (5). One end of the servo motor (4) is fixedly connected to the U-shaped fixed plate (5), and the other end is connected to the U-shaped movable plate (3) for transmission. The drive component is fixedly installed on the U-shaped movable plate (3), and the U-shaped fixed plate (5) is connected to the mounting component.

4. The trapezoidal flying wing tiltrotor aircraft according to claim 3, characterized in that, The mounting components include a first tube (6), a second tube (7), an O-ring clip (8), a side plate (9), and a support plate (10). The first tube (6) is fixed to the wingtip (B) of the wing (2), and the second tube (7) is fixed to the wing root (A) of the wing (2). The O-ring clip (8) is fixed to the first tube (6) and the second tube (7) respectively, and the side of the O-ring clip (8) is connected to the side plate (9). The end of the side plate (9) away from the O-ring clip (8) is fixedly connected to the support plate (10). The support plate (10) is connected to the U-shaped fixing plate (5).

5. The trapezoidal flying wing tiltrotor aircraft according to claim 4, characterized in that, The first tube (6) and the second tube (7) are both made of carbon fiber material, with a tensile strength greater than 3400MPa; After the second tube (7) is installed, it can ensure that the rear rotor does not interfere with the wing (2) and adjacent rotors when it is working.

6. The trapezoidal flying wing tiltrotor aircraft according to claim 1, characterized in that, In level flight, the front rotor rotates outward toward the wingtip (B) and the rear rotor rotates inward toward the fuselage (1) axis of symmetry. The distance between the rotation axes of adjacent rotors in the wingspan direction is greater than the equivalent diameter of the rotor's rotating sweep surface.

7. The trapezoidal flying wing tiltrotor aircraft according to claim 1, characterized in that, The four rotors have the same structure. When working, the adjacent rotors rotate in opposite directions, the rotors set diagonally rotate in the same direction, and the adjacent rotors are those that are close to each other. In the trapezoid formed by the four rotors, the rotors on the diagonal are the farthest apart and are not adjacent rotors.

8. The trapezoidal flying wing tiltrotor aircraft according to claim 1, characterized in that, The tilt range of the rotor is 0-90°, with 0° corresponding to vertical take-off and landing and hovering, and 90° corresponding to level flight. If the wing (2) has an upward dihedral angle, the rotor's rotation axis can be kept perpendicular to the horizontal plane in the initial state by adjusting the tilt drive assembly.

9. The trapezoidal flying wing tiltrotor aircraft according to claim 1, characterized in that, The fuselage (1) and wings (2) are structural forms with a frame covered by a skin.

10. The trapezoidal flying wing tiltrotor aircraft according to any one of claims 1-9, characterized in that, The aircraft has a symmetrical structure.

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