Distributed ducted rotor combined short-distance vertical take-off and landing unmanned aerial vehicle and control mode thereof

Abstract

The invention belongs to the field of aviation aircraft design, and discloses a short-distance vertical take-off and landing unmanned aerial vehicle with distributed duct rotor wing combinations and a control mode of the short-distance vertical take-off and landing unmanned aerial vehicle. The unmanned aerial vehicle adopts a wing body fusion layout, and an empennage adopts a T-tail layout; the wings on the two sides of the fuselage are sequentially divided into inner wings and outer wings from inside to outside; on-wing fusion design is adopted, distributed ducted power modules in bilateral symmetry are arranged on the rear portion of the upper surface of a wing, and each distributed ducted power module comprises parallel ducted fans with the same number; a rotor support rod is mounted between the inner wing and the outer wing and adopts an anti-symmetric rod type appearance, a pull-type rotor is mounted at the front end, and a push-type rotor is mounted at the rear end; steering engines are installed in inner cavities of the rotor wing supporting rods. The control modes comprise a cruise mode, a vertical take-off and landing mode and a short-distance take-off and landing mode. Short-distance take-off and landing and vertical take-off and landing can be achieved, the multi-target conflict problem that in the plateau environment, the take-off and landing site is limited, the loading performance is insufficient, and the wind resistance is weak is solved, and the method has the engineering practical value.

Description

Technical Field

[0001] The present invention belongs to the field of aircraft design, and particularly relates to a short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination and its control mode. Background Art

[0002] The high altitude, low density, complex terrain and strong wind interference environment in plateau areas pose severe challenges to the application of unmanned aerial vehicles. Existing various unmanned aerial vehicle platforms all have significant limitations in the plateau environment: multi-rotor unmanned aerial vehicles face problems such as a significant decline in load-carrying performance and limited flight speed; compound-wing unmanned aerial vehicles have defects such as insufficient payload capacity and poor wind resistance stability; conventional takeoff and landing unmanned aerial vehicles with runway takeoff and landing are difficult to meet the special requirements of the plateau complex terrain for takeoff and landing sites; rocket-boosted and parachute-dropped unmanned aerial vehicles have weak wind resistance due to high plateau use and maintenance costs, high recovery risks, and low wing loading design, and the effective operation time window is limited.

[0003] Regarding the core problem of the application of unmanned aerial vehicles in the plateau environment - the coordinated optimization of takeoff and landing performance and wind resistance ability, currently two technical routes are adopted: for short takeoff and landing unmanned aerial vehicles, by increasing the wing area to improve the lift efficiency and reduce the takeoff and landing speed, the technical advantages are mainly reflected in aspects such as larger payload, higher cruise speed, and better energy efficiency. However, limited by the low wing loading design and insufficient wind disturbance resistance ability, it is difficult to meet the requirements of full-scenario applications in the plateau. For vertical takeoff and landing aircraft, the vertical takeoff and landing function is achieved through power deflection or conversion; taking the tilt-rotor unmanned aerial vehicle as an example, the mode conversion between vertical takeoff and landing and high-speed cruise is achieved through rotor tilting. However, the aerodynamic interference effect is significant during its mode conversion, and the complex aerodynamic coupling increases the design difficulty of the control system. At the same time, as the altitude increases and the flight speed increases, the rotor force efficiency decays significantly, resulting in limited payload capacity.

[0004] The above two technical routes both face common problems in the plateau environment: it is difficult to achieve a coordinated breakthrough in load performance, wind resistance ability, and all-terrain adaptability. Currently, there is an urgent need to develop a systematic solution through innovative aerodynamic layout and optimized power system, and to develop a short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination and its control mode. Summary of the Invention

[0005] One technical problem to be solved by the present invention is to provide a short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination, and another technical problem to be solved by the present invention is to provide a control mode for the short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination.

[0006] The short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination of the present invention adopts a wing-body fusion layout, and the tail wing adopts a T-tail layout; The wings on both sides of the fuselage are divided into inner wings and outer wings from the inside to the outside. The rear part of the upper surface of the inner wing adopts a wing-on-wing fusion design and is equipped with a bilaterally symmetrical distributed ducted power module. The distributed ducted power modules on both sides include the same number of parallel ducted fans. A rotor strut is installed between the inner and outer wings, with the central axis of the rotor strut parallel to the central axis of the fuselage; the rotor strut adopts an anti-symmetric rod shape, with the front facing the nose and the rear facing the tail; the front rotor is installed at the front end of the rotor strut, and the front rotor is a traction rotor, and the rear end is installed at the rear end, and the rear rotor is a pusher rotor; a servo is installed in the inner cavity of the rotor strut, and the chordwise position deviation between the center of the rotor strut and the center of gravity of the drone is no more than 5% of the average aerodynamic chord length of the wing; the servo simultaneously controls the corresponding front and rear rotors to tilt; The tail consists of a horizontal tail and a vertical tail, and the horizontal tail is located at the top of the vertical tail.

[0007] Furthermore, the number of ducted fans in the distributed ducted power module is not less than 5; the distributed ducted power module on the left is divided into several ducted power units from the inside to the outside, and the distributed ducted power module on the right is divided into several corresponding ducted power units from the inside to the outside; the ducted power unit adopts distributed control to realize distributed differential control of the distributed ducted power module on the left and the distributed ducted power module on the right.

[0008] Furthermore, the installation angle of the ducted fan is 0°~15°, and the installation angle is the angle between the thrust line of the ducted fan and the central axis of the fuselage.

[0009] Furthermore, the process of selecting the installation angle is as follows: S10. Based on the local chord length of the wing airfoil and the location of the distributed ducted power module, preliminarily determine the range of the installation angle. The ducted fan's inlet duct must blend with the curved surface of the wing's upper surface to prevent airflow separation and ensure that the ducted fan can effectively remove the boundary layer from the wing's upper surface. S20. The installation angle is determined so that the thrust of the ducted fan has a lift component. The installation angle is ultimately determined based on the balance between the short takeoff and landing requirements and the load capacity of the UAV.

[0010] Furthermore, the front rotor and the rear rotor are both two-blade propellers or folding multi-blade propellers.

[0011] Furthermore, the tilt directions of the front rotor and the rear rotor are both downward, and the rotor tilt angle range is 0°~25°; the front rotor includes a left front rotor and a right front rotor that are bilaterally symmetrical, and the rear rotor includes a left rear rotor and a right rear rotor that are bilaterally symmetrical; The four rotors adopt an independent control mode or a combined control mode; in the independent control mode, the operating states of the four rotors are independently controlled to jointly maintain the flight attitude of the UAV; in the combined control mode, except for the rotation direction, the operating states of the four rotors are kept consistent, and the flight attitude of the UAV is jointly maintained through rudder surface control and distributed differential control of the distributed ducted power module.

[0012] The control mode of the short takeoff and vertical landing UAV with a distributed ducted rotor combination of the present invention includes a cruise mode, a vertical takeoff and landing mode, and a short takeoff and landing mode; In the cruise mode, the UAV maintains a set flight speed at a set flight altitude with the ducted power as the sole power source; the sum of the lift generated by the fixed wing of the UAV and the lift components provided by the distributed ducted power modules on both sides is sufficient to meet the lift requirement of the UAV. The power of the four rotors is reduced to completely closed, and the front rotor and the rear rotor are retracted and fixed along the oncoming flow direction through the clamping mechanism to reduce the flight resistance of the UAV; In the vertical takeoff and landing mode, the rotor power is the main power and the ducted power is the auxiliary power; during vertical takeoff, the four rotors are the sole power source for takeoff, adopting the independent control mode, with the rotor inclination angle being zero and the power direction being vertically upward to lift the UAV to the set flight altitude and then hover; subsequently, the rotors are tilted and the combined control mode is adopted, and the distributed ducted power module is synchronously started to obtain the ducted power, and the UAV enters the acceleration stage, accelerating to the set flight speed. During the acceleration process, the UAV maintains the flight altitude or is in a climbing state; after the acceleration stage is completed, it switches to the cruise mode; during vertical landing, the UAV enters the deceleration stage. The four rotors adopt the independent control mode, and the rotor power is synchronously turned on and gradually increased respectively to ensure that the UAV descends slowly. At the same time, the ducted power is slowly turned off until the ducted power is completely turned off, decelerating the UAV to the hover state, and then continuing to reduce the rotor power to lower the altitude of the UAV until the UAV stops on the ground; In the short takeoff and landing mode, the ducted fan power is the main power, and the rotor power is the auxiliary power. During the takeoff process of the short takeoff and landing mode, the rotor power adopts a combined control mode, and the ducted fan power unit adopts distributed control. After the rotor inclination angle deflects to the predetermined maximum angle, the ducted fan power and the rotor power work together, and the UAV is subjected to a dual thrust force and accelerates for a ground run, reducing the ground run distance. The lift direction components of the ducted fan power and the rotor power effectively reduce the takeoff liftoff speed and increase the takeoff load. When the UAV is in a climbing state, the combined power of the ducted fan power and the rotor power increases the climbing speed of the UAV. After the climbing state turns into the level flight stage, gradually reduce the share of the rotor power until the rotor power is turned off, the rotor inclination angle returns to zero and enters the cruise mode. During the landing process of the short takeoff and landing mode, the UAV gradually decelerates from the cruise state, activates the rotor power, reduces the ducted fan power, and the total thrust force in the forward direction gradually decreases. When approaching the runway, adjust the landing attitude of the UAV and further reduce or turn off the ducted fan power. The rotor provides a backward resistance component and an upward lift component to further reduce the landing speed of the UAV. After entering the landing ground run stage, reduce or turn off the rotor power and use the landing gear brakes to decelerate until the UAV stops.

[0013] Furthermore, during the climbing state, the rotor inclination angle is consistent with the angle of attack of the UAV, increasing the lift component of the rotor power and improving the climbing efficiency of the UAV. During the landing process, the rotor inclination angle is zero, and the rotor power provides a resistance component. The magnitude of the resistance component depends on the flight attitude of the UAV, and the rotor power is used to accelerate the air deceleration process of the UAV.

[0014] Furthermore, in a crosswind environment, the control mode provides a control moment through the distributed differential control of the ducted fan power, increasing the wind resistance ability of the UAV.

[0015] The short takeoff and vertical landing UAV with a distributed ducted fan and rotor combination and its control mode of the present invention are not restricted by complex terrains and have both vertical takeoff and landing and short takeoff and landing capabilities. In the vertical takeoff and landing mode, the power is provided by the rotor power. In the short takeoff and landing mode, a combined power is provided by the ducted fan power and the rotor power. The ducted fan power is the main thrust source. After the rotor tilts to the maximum angle, it provides a thrust component, and the output value of the rotor power can be controlled in real time according to the runway length and takeoff weight. In the case of low load and good runway conditions, the rotor power can be selectively activated. In complex terrains such as plateaus or in the case of large loads, the output of the rotor power can be increased according to the takeoff and landing requirements of the UAV.

[0016] The short takeoff and vertical landing UAV with a distributed ducted fan and rotor combination and its control mode of the present invention have the following characteristics: 1. It realizes takeoff and landing under complex conditions in plateau areas; Vertical takeoff and landing gets rid of the restrictions of takeoff and landing sites; short takeoff and landing can reduce the runway class requirements under large payload conditions and even enable takeoff and landing on roads; 2. It increases the wing loading and wind resistance performance of the aircraft wing; Through distributed ducted power lift augmentation, the wing loading of the aircraft wing is increased; through the distributed differential control of the ducted power, the wind resistance level from level 1 to level 2 is improved (the corresponding wind speed threshold increases by 4 m / s to 8 m / s); by adopting a multi-unit distributed control strategy, the difficulty of the distributed differential control of the ducted power is reduced; 3. It realizes the integration and lightweight of the tilt-rotor; For the tilt-rotor, an angle limit strategy and an anti-symmetric rotor strut design are adopted. The front and rear rotors of the same strut share a single servo. While meeting the flight requirements, the structural burden caused by the tilt-rotor is reduced.

[0017] The short takeoff and vertical takeoff unmanned aerial vehicle with a distributed ducted rotor combination and its control mode of the present invention achieve short takeoff and vertical takeoff; vertical takeoff is realized by using rotor power, and short takeoff in high-altitude environments and under large payloads is realized by using ducted power; the ducted power effectively increases the wing loading of the aircraft wing, realizes distributed differential control, and enhances the wind resistance performance of the unmanned aerial vehicle; it solves the multi-objective conflict problem of "restricted takeoff and landing sites - insufficient payload performance - weak wind resistance ability" of unmanned aerial vehicles in high-altitude environments and has engineering practical value. Brief Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram (3D view) of the short takeoff and vertical takeoff unmanned aerial vehicle with a distributed ducted rotor combination of the present invention; Figure 2 It is a schematic structural diagram (top view) of the short takeoff and vertical takeoff unmanned aerial vehicle with a distributed ducted rotor combination of the present invention; Figure 3 It is a schematic diagram of the rotor strut and rotor tilt in the short takeoff and vertical takeoff unmanned aerial vehicle with a distributed ducted rotor combination of the present invention.

[0019] In the figure, 1. fuselage; 2. inner wing; 3. outer wing; 4. horizontal tail; 5. vertical tail; 6. rotor strut; 7. distributed ducted power module; 8. front rotor; 9. rear rotor; 10. unmanned aerial vehicle center of gravity; 11. servo; 701. Ducted power unit Ⅰ; 702. Ducted power unit Ⅱ; 703. Ducted power unit Ⅲ; 704. Ducted power unit Ⅳ; 705. Ducted power unit Ⅴ; 706. Ducted power unit Ⅵ; 801. Left front rotor; 802. Right front rotor; 901. Left rear rotor; 902. Right rear rotor. Detailed Description of the Invention

[0020] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0021] like Figures 1 to 3 As shown, the distributed ducted rotor combination short-range vertical take-off and landing UAV of the present invention adopts a wing-body fusion layout, and the tail adopts a T-tail layout; The wings on both sides of the fuselage 1 are divided into inner wings 2 and outer wings 3 from the inside to the outside. The rear portion of the upper surface of the inner wing 2 adopts a wing-on-wing fusion design and is provided with bilaterally symmetrical distributed ducted power modules 7. The distributed ducted power modules 7 on both sides include the same number of parallel ducted fans. A rotor strut 6 is installed between the inner wing 2 and the outer wing 3, and the central axis of the rotor strut 6 is parallel to the central axis of the fuselage 1; the rotor strut 6 adopts an anti-symmetric rod shape, with the front facing the nose and the rear facing the tail; the front end of the rotor strut 6 is installed with a front rotor 8, which is a traction rotor, and the rear end is installed with a rear rotor 9, which is a pusher rotor; a steering gear 11 is installed in the inner cavity of the rotor strut 6, and the chordwise position deviation between the center of the rotor strut 6 and the center of gravity 10 of the UAV is no more than 5% of the average aerodynamic chord length of the wing; the steering gear 11 simultaneously controls the corresponding front rotor 8 and rear rotor 9 to tilt; while meeting the flight requirements of the UAV, the structural burden of the steering gear 11 on the UAV is reduced; The tail comprises a horizontal tail 4 and a vertical tail 5 , wherein the horizontal tail 4 is located at the top end of the vertical tail 5 .

[0022] Furthermore, the number of ducted fans in the distributed ducted power module 7 is not less than 5; the distributed ducted power module 7 on the left is divided into several ducted power units from the inside to the outside, and the distributed ducted power module 7 on the right is divided into several corresponding ducted power units from the inside to the outside; the ducted power units adopt distributed control to realize distributed differential control of the distributed ducted power module 7 on the left and the distributed ducted power module 7 on the right.

[0023] Furthermore, the installation angle of the ducted fan is 0°~15°, and the installation angle is the angle between the thrust line of the ducted fan and the central axis of the fuselage 1.

[0024] Furthermore, the process of selecting the installation angle is as follows: S10. Preliminarily determine the installation angle range based on the wing airfoil and the local chord length of the distributed ducted power module 7. This requires that the ducted fan's inlet duct blends with the curved surface of the wing's upper surface to prevent airflow separation and ensure that the ducted fan removes the boundary layer from the wing's upper surface. S20. The installation angle is determined so that the ducted fan thrust has a lift component. The installation angle is ultimately determined based on the balance between the short takeoff and landing requirements and the payload capacity of the UAV.

[0025] Further, both the front rotor 8 and the rear rotor 9 are two-blade propellers or foldable multi-blade propellers.

[0026] Further, the tilting directions of both the front rotor 8 and the rear rotor 9 are the head-down direction, and the rotor tilt angle ranges from 0° to 25°; the front rotor 8 includes a left front rotor 801 and a right front rotor 802 that are symmetric about the left and right, and the rear rotor 9 includes a left rear rotor 901 and a right rear rotor 902 that are symmetric about the left and right; The four rotors adopt an independent control mode or a combined control mode; in the independent control mode, the operating states of the four rotors are independently controlled to jointly maintain the flight attitude of the UAV; in the combined control mode, except for the rotation direction, the operating states of the four rotors are kept consistent, and the flight attitude of the UAV is jointly maintained through rudder surface control and distributed differential control of the distributed ducted power module 7.

[0027] The control mode of the short takeoff and vertical landing UAV with a distributed ducted rotor combination of the present invention includes a cruise mode, a vertical takeoff and landing mode, and a short takeoff and landing mode; In the cruise mode, the UAV maintains a set flight speed at a set flight altitude, with the ducted power as the only power source; the sum of the lift generated by the fixed wing of the UAV and the lift components provided by the distributed ducted power modules 7 on both sides is sufficient to meet the lift requirement of the UAV. The power of the four rotors is reduced to completely shut down, and the front rotor 8 and the rear rotor 9 are retracted and fixed along the oncoming flow direction through a clamping mechanism to reduce the flight resistance of the UAV; In the vertical takeoff and landing mode, the rotor power is the main power and the ducted power is the auxiliary power; during vertical takeoff, the four rotors are the only power source for takeoff, adopting an independent control mode, with the rotor tilt angle being zero and the power direction being vertically upward to lift the UAV to a set flight altitude and then hover; subsequently, the rotor 9 tilts and adopts a combined control mode, and the distributed ducted power module 7 is synchronously started to obtain ducted power, and the UAV enters the acceleration stage, accelerating to a set flight speed. During the acceleration process, the UAV maintains the flight altitude or is in a climbing state; after the acceleration stage is completed, it enters the cruise mode; during vertical landing, the UAV enters the deceleration stage, and the four rotors adopt an independent control mode. The rotor power is synchronously turned on and gradually increased respectively to ensure that the UAV descends slowly, and at the same time, the ducted power is slowly turned off until it is completely turned off, decelerating the UAV to a hovering state, and then continuing to reduce the rotor power to lower the altitude of the UAV until the UAV stops on the ground; In the short takeoff and landing mode, the ducted fan power is the main power, and the rotor power is the auxiliary power; during the takeoff process of the short takeoff and landing mode, the rotor power adopts a combined control mode, and the ducted fan power unit adopts distributed control. After the rotor inclination angle deflects to the predetermined maximum angle, the ducted fan power and the rotor power work together, and the unmanned aerial vehicle (UAV) is subjected to a double thrust force and performs accelerated taxiing, reducing the taxiing distance; the lift direction components of the ducted fan power and the rotor power effectively reduce the takeoff liftoff speed and increase the takeoff load; when the UAV is in the climbing state, the combined power of the ducted fan power and the rotor power increases the climbing speed of the UAV; after the climbing state transitions to the level flight stage, gradually reduce the share of the rotor power until the rotor power is turned off, the rotor inclination angle returns to zero and enters the cruise mode; during the landing process of the short takeoff and landing mode, the UAV gradually decelerates from the cruise state, activates the rotor power, reduces the ducted fan power, and keeps the total thrust in the forward direction gradually decreasing; when approaching the runway, adjust the landing attitude of the UAV and further reduce or turn off the ducted fan power. The rotor provides a backward resistance component and an upward lift component to further reduce the landing speed of the UAV; after entering the landing taxiing stage, reduce or turn off the rotor power and use the landing gear brakes to decelerate until the UAV stops.

[0028] Furthermore, during the climbing state, the rotor inclination angle is consistent with the angle of attack of the UAV, increasing the lift component of the rotor power and improving the climbing efficiency of the UAV; during the landing process, the rotor inclination angle is zero, and the rotor power provides a resistance component. The magnitude of the resistance component depends on the flight attitude of the UAV, and the rotor power is used to accelerate the air deceleration process of the UAV.

[0029] Furthermore, in a crosswind environment, the control mode provides a control torque through the distributed differential control of the ducted fan power, increasing the wind resistance ability of the UAV.

[0030] Embodiment: The distributed ducted fan power modules 7 on the left and right sides of this embodiment each include 8 ducted fans. The outer diameter of the ducted fan is 120 mm, and the installation angle of the ducted fan is 9°.

[0031] As Figure 2 shown, the 8 ducted fans of the distributed ducted fan power module 7 on the left side are sequentially divided into ducted fan power unit Ⅰ701, ducted fan power unit Ⅱ702, and ducted fan power unit Ⅲ703 from the inside to the outside, with 3, 2, and 3 ducted fans respectively; the distributed ducted fan power module 7 on the right side is sequentially divided into corresponding ducted fan power unit Ⅳ704, ducted fan power unit Ⅴ705, and ducted fan power unit Ⅵ706 from the inside to the outside, with 3, 2, and 3 ducted fans respectively; through the precise control of the working states of the 6 power units, distributed differential control of the ducted fan power is achieved to provide the thrust required by the UAV.

[0032] As Figure 3As shown, both the front rotor 8 and the rear rotor 9 of this embodiment adopt two-blade paddles, and the inclination angle of the front rotor 8 is θ 1 , and the inclination angle of the rear rotor 9 is θ 2 , θ 1 = θ 2 ; the chordal distance between the center of rotation of the front rotor 8 and the center of gravity 10 of the UAV is , and the chordal distance between the center of rotation of the rear rotor 9 and the center of gravity 10 of the UAV is , .

[0033] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, without departing from the principle of the present invention, all the features disclosed in the present invention, or all the steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way. The present invention is not limited to the specific details and the illustrated examples here.

Claims

1. A short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination, characterized in that The UAV adopts a wing-body fusion layout, and the tail adopts a T-tail layout; The wings on both sides of the fuselage (1) are divided into inner wings (2) and outer wings (3) from the inside to the outside; the rear portion of the upper surface of the inner wing (2) adopts a wing-on-wing fusion design, and is provided with a left-right symmetrical distributed ducted power module (7), and the distributed ducted power modules (7) on both sides include the same number of parallel ducted fans; A rotor strut (6) is installed between the inner wing (2) and the outer wing (3), and the central axis of the rotor strut (6) is parallel to the central axis of the fuselage (1); the rotor strut (6) adopts an anti-symmetric rod shape, with the front facing the nose and the rear facing the tail; the front end of the rotor strut (6) is installed with a front rotor (8), which is a traction rotor, and the rear end is installed with a rear rotor (9), which is a pusher rotor; a steering gear (11) is installed in the inner cavity of the rotor strut (6), and the chordwise position deviation between the center of the rotor strut (6) and the center of gravity (10) of the UAV is not greater than 5% of the average aerodynamic chord length of the wing; the steering gear (11) simultaneously controls the corresponding front rotor (8) and rear rotor (9) to tilt; The tail wing comprises a horizontal tail wing (4) and a vertical tail wing (5), wherein the horizontal tail wing (4) is located at the top end of the vertical tail wing (5).

2. The short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 1, wherein The number of ducted fans in the distributed ducted power module (7) is not less than 5; the distributed ducted power module (7) on the left is divided into a plurality of ducted power units from the inside to the outside, and the distributed ducted power module (7) on the right is divided into a plurality of corresponding ducted power units from the inside to the outside; the ducted power units adopt distributed control to realize distributed differential control of the distributed ducted power module (7) on the left and the distributed ducted power module (7) on the right.

3. The short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 1, wherein The installation angle of the ducted fan is 0° to 15°, and the installation angle is the angle between the thrust line of the ducted fan and the central axis of the fuselage (1).

4. The short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 3, wherein, The process of selecting the installation angle is as follows: S10. Based on the local chord length of the wing airfoil and the position of the distributed ducted power module (7), the range of the installation angle is preliminarily determined, requiring the air intake duct of the ducted fan to be integrated with the curved surface of the wing upper surface so that no airflow separation occurs, ensuring that the ducted fan can achieve boundary layer suction on the wing upper surface; S20. The installation angle is determined so that the ducted fan thrust has a lift component. The installation angle is ultimately determined based on the balance between the short takeoff and landing requirements and the payload capacity of the UAV.

5. The short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 1, characterized in that, The front rotor (8) and the rear rotor (9) are both two-blade propellers or folding multi-blade propellers.

6. The short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 1, characterized in that The tilting directions of the front rotor (8) and the rear rotor (9) are both downward-facing directions, and the rotor tilt angle range is 0° to 25°; the front rotor (8) includes a left front rotor (801) and a right front rotor (802) that are symmetrical on both sides, and the rear rotor (9) includes a left rear rotor (901) and a right rear rotor (902) that are symmetrical on both sides; The four rotors adopt an independent control mode or a combined control mode; in the independent control mode, the working states of the four rotors are independently controlled to jointly maintain the flight attitude of the UAV; in the combined control mode, except for the rotation direction, the working states of the four rotors are kept consistent, and the flight attitude of the UAV is jointly maintained through the control of the control surface and the distributed differential control of the distributed ducted power module (7).

7. A control mode for a short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination, which is used for the short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to any one of claims 1 to 6, characterized in that, The control modes include a cruise mode, a vertical takeoff and landing mode, and a short takeoff and landing mode; In the cruise mode, the UAV maintains a set flight speed at a set flight altitude with the ducted power as the sole power source; the sum of the lift generated by the fixed wing of the UAV and the lift components provided by the distributed ducted power modules (7) on both sides is sufficient to meet the lift requirement of the UAV. The power of the four rotors is reduced to completely shut down, and the front rotor (8) and the rear rotor (9) are retracted and fixed along the oncoming flow direction through the clamping mechanism to reduce the flight resistance of the UAV; In the vertical takeoff and landing mode, the rotor power is the main power and the ducted power is the auxiliary power; during vertical takeoff, the four rotors are the sole power source for takeoff and adopt an independent control mode. The rotor inclination angle is zero, and the power direction is vertically upward to lift the UAV to a set flight altitude and then hover; subsequently, the rotor (9) tilts and adopts a combined control mode, and the distributed ducted power module (7) is synchronously started to obtain the ducted power, and the UAV enters the acceleration stage and accelerates to a set flight speed. During the acceleration process, the UAV maintains the flight altitude or is in a climbing state; after the acceleration stage is completed, it switches to the cruise mode; during vertical landing, the UAV enters the deceleration stage. The four rotors adopt an independent control mode, and the rotor power is synchronously turned on and gradually increased respectively to ensure that the UAV descends slowly. At the same time, the ducted power is slowly turned off until the ducted power is completely turned off, and the UAV is decelerated to a hover state, and then the rotor power is further reduced to lower the altitude of the UAV until the UAV stops on the ground; In the short takeoff and landing mode, the ducted fan power is the main power and the rotor power is the auxiliary power. During the takeoff process of the short takeoff and landing mode, the rotor power adopts a combined control mode, and the ducted fan power unit adopts distributed control. After the rotor inclination angle deflects to the predetermined maximum angle, the ducted fan power and the rotor power work together. The UAV is subjected to double thrust and accelerates for taxiing, reducing the taxiing distance. The lift direction components of the ducted fan power and the rotor power effectively reduce the takeoff ground speed and increase the takeoff load. When the UAV is in the climbing state, the combined power of the ducted fan power and the rotor power increases the climbing speed of the UAV. After the climbing state turns into the level flight stage, the share of the rotor power is gradually reduced until the rotor power is turned off, the rotor inclination angle returns to zero and enters the cruise mode. During the landing process of the short takeoff and landing mode, the UAV gradually decelerates from the cruise state, the rotor power is enabled, the ducted fan power is reduced, and the total thrust in the forward direction gradually decreases. When approaching the runway, the landing attitude of the UAV is adjusted and the ducted fan power is further reduced or turned off. The rotor provides a backward resistance component and an upward lift component to further reduce the landing speed of the UAV. After entering the landing taxiing stage, the rotor power is reduced or turned off, and the landing gear brakes are used to decelerate until the UAV stops.

8. The control mode of the short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 7, characterized in that, During the climbing state, the rotor inclination angle is consistent with the angle of attack of the UAV, increasing the lift component of the rotor power and improving the climbing efficiency of the UAV. During the landing process, the rotor inclination angle is zero, and the rotor power provides a resistance component. The magnitude of the resistance component depends on the flight attitude of the UAV, and the rotor power is used to accelerate the air deceleration process of the UAV.

9. The control mode of the short takeoff and vertical landing unmanned aerial vehicle with a distributed ducted rotor combination according to claim 7, characterized in that, In the control mode, in a crosswind environment, a control moment is provided through the distributed differential control of the ducted fan power, increasing the wind resistance ability of the UAV.

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