A ducted unmanned aerial vehicle

Abstract

The application provides a ducted unmanned aerial vehicle, and relates to the technical field of unmanned aerial vehicles, which comprises a wing and a duct, the wing comprises a wing-body combination, an outer wing and an aileron, the outer wing is installed on the left and right sides of the wing-body combination, the aileron is movably installed at the tail of the wing-body combination, the duct is installed between the outer wing and the wing-body combination, the length direction of the duct is parallel to the length direction of the unmanned aerial vehicle, and a fan rotating in the length direction of the duct is installed in the duct. The unmanned aerial vehicle has a double-rotor flight mode and a fixed-wing flight mode. In the double-rotor flight mode, the inclination angle of the unmanned aerial vehicle is greater than or equal to 45 DEG, the vertical component of the fan thrust is greater than the vertical component of the wing lift, in the fixed-wing flight mode, the inclination angle of the unmanned aerial vehicle is less than or equal to 45 DEG, the vertical component of the fan thrust is less than the vertical component of the wing lift, and the fan is also used for providing thrust to ensure that the flight height of the unmanned aerial vehicle is unchanged when the flight mode of the unmanned aerial vehicle is switched.

Description

Technical Field

[0001] This application relates to the field of unmanned aerial vehicle (UAV) technology, and more specifically, to a ducted unmanned aerial vehicle (UAV). Background Technology

[0002] In recent years, unmanned aerial vehicle (UAV) technology has been widely used in both civilian and military fields, particularly excelling in aerial surveying, agricultural protection, logistics, and emergency rescue. As demands continue to rise, users are placing higher requirements on UAV performance, especially the ability to simultaneously possess long endurance, high-speed flight, and vertical takeoff and landing capabilities. However, the configuration and manufacturing processes of existing UAV platforms limit their overall performance, making it difficult to meet these demands concurrently.

[0003] Existing drone platforms can be mainly divided into two categories: fixed-wing drones and multi-rotor drones. Fixed-wing drones have longer endurance and higher flight speeds, but they require runways for takeoff and landing, have high site requirements, and lack flexibility, making them unsuitable for use in restricted environments. Multi-rotor drones can take off and land vertically, possessing strong maneuverability and flexibility, making them suitable for confined spaces and complex environments. However, they have lower aerodynamic efficiency, shorter endurance, and slower flight speeds, making them difficult to handle long-duration, high-speed flight missions.

[0004] To combine the advantages of fixed-wing and multi-rotor aircraft, existing technologies have proposed a tilt-ducted unmanned aerial vehicle (UAV) configuration. This involves arranging a ducted propulsion unit on the fuselage, enabling the UAV to achieve both vertical takeoff and landing (VTOL) and, to a certain extent, high-speed horizontal flight, thus switching between the two flight modes. For example, in patent application CN117429639A, the UAV achieves switching between vertical and horizontal flight modes by changing the installation direction of the duct relative to the fuselage. However, this approach requires the introduction of additional shafts, hinge mechanisms, and transmission components between the fuselage and the duct, significantly increasing the overall structural complexity, manufacturing and assembly difficulties, and overall weight, which is detrimental to improving thrust-to-weight ratio and endurance. Furthermore, the arrangement and tilting of the duct on the fuselage result in discontinuous transitions in the fuselage shape. During VTOL operations, the large frontal area leads to uneven airflow and increased drag, resulting in lower aerodynamic efficiency during vertical flight and impacting wind resistance and energy utilization. Furthermore, the small wing area limits the lift it can provide in level flight, making it difficult to fully utilize the advantages of efficient cruise for fixed-wing aircraft. It also results in insufficient attitude stability during the transition from vertical to level flight, making it difficult to achieve a smooth and reliable mode switch.

[0005] In summary, existing fixed-wing and multi-rotor UAVs each have significant shortcomings in terms of endurance and takeoff / landing conditions. While tilt-ducted UAVs attempt to combine the advantages of both, they are still constrained by the complexity of the tilt mechanism, unreasonable aerodynamic transition, and insufficient lift during level flight, making it difficult to achieve a good balance between vertical takeoff and landing capability, level flight efficiency, and smooth transition. How to achieve efficient and smooth transitions between vertical and level flight modes while maintaining relatively simple structure and controllable mass remains a technical problem that needs further resolution in the UAV field. Utility Model Content

[0006] The purpose of this application is to provide a ducted unmanned aerial vehicle (UAV) that addresses the shortcomings of the aforementioned technologies.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a ducted unmanned aerial vehicle (UAV) including a wing and a duct. The wing includes a blended wing-body, an outer wing, and an aileron. The outer wings are installed on the left and right sides of the blended wing-body, and the aileron is movably installed at the tail of the blended wing-body. The duct is installed between the outer wings and the blended wing-body, and the length direction of the duct is parallel to the length direction of the UAV. A fan that rotates around the length direction is installed inside the duct. The wing root of the leading edge of the outer wing is flush with the air inlet of the duct, and the wing root of the trailing edge of the outer wing is flush with the air outlet of the duct. The drone has a dual-rotor flight mode and a fixed-wing flight mode. In dual-rotor flight mode, the drone's tilt angle is greater than or equal to 45°, and the vertical component of the fan thrust is greater than the vertical component of the wing lift. In fixed-wing flight mode, the drone's tilt angle is less than or equal to 45°, and the vertical component of the fan thrust is less than the vertical component of the wing lift. The fan is also used to provide thrust when the drone switches flight modes to ensure that the drone's flight altitude remains unchanged when switching flight modes.

[0008] Furthermore, a flight control board is installed on the blended wing-body. The flight control board is used to adjust the rotation direction of the ailerons to switch the flight mode of the drone based on the ratio of the vertical component of the fan thrust to the vertical component of the wing lift and the horizontal forward speed of the drone.

[0009] Furthermore, in dual-rotor flight mode, the fans in the left and right ducts rotate asynchronously to adjust the roll attitude of the drone, the ailerons on the left and right sides rotate synchronously in the same direction to adjust the pitch attitude of the drone, and the ailerons on the left and right sides rotate synchronously in opposite directions to adjust the yaw attitude of the drone. In fixed-wing flight mode, the fans in the ducts on both sides rotate asynchronously to adjust the yaw attitude of the drone, the ailerons on both sides rotate synchronously in the same direction to adjust the pitch attitude of the drone, and the ailerons on both sides rotate synchronously in opposite directions to adjust the roll attitude of the drone.

[0010] Furthermore, the aileron includes a first wing section and a second wing section connected along the width direction of the UAV. The first wing section is directly opposite the trailing edge of the outer wing, and the second wing section is directly opposite the air outlet of the duct. Part of the airflow flowing from the head to the tail of the UAV flows from the air outlet of the duct to the first wing section to form an airflow stabilization zone, thereby reducing the interference area of ​​the airflow flowing from the tail to the head of the UAV on the aileron.

[0011] Furthermore, the wings are made using 3D printing.

[0012] Furthermore, the sweep angle of the outer wing leading edge is 20° to 30°.

[0013] Furthermore, the drone's center of gravity is located at 8% to 12% of the average aerodynamic chord length in front of the drone's focal point.

[0014] Furthermore, winglets are provided at the wingtips of the outer wing.

[0015] Furthermore, a triangular support is installed in the middle of the tail of the blended wing-body structure to support the take-off and landing of the drone.

[0016] Furthermore, two servos are installed on the blended wing-body, each connected to a different aileron, to independently drive the corresponding aileron to rotate relative to the blended wing-body.

[0017] The beneficial effects of this application include: This application provides a ducted unmanned aerial vehicle (UAV) including a wing and a duct. The wing includes a blended wing-body, outer wings, and ailerons. Outer wings are mounted on the left and right sides of the blended wing-body, and ailerons are movably mounted at the tail of the blended wing-body. A duct is installed between the outer wings and the blended wing-body, with the length direction of the duct parallel to the length direction of the UAV. A fan rotating around the length direction is installed inside the duct. The wing root at the leading edge of the outer wing is flush with the air inlet of the duct, and the wing root at the trailing edge of the outer wing is flush with the air outlet of the duct. The UAV has a dual-rotor flight mode and a fixed-wing flight mode. In dual-rotor flight mode, the UAV's tilt angle is greater than or equal to 45°, and the vertical component of the fan thrust is greater than the vertical component of the wing lift. In fixed-wing flight mode, the UAV's tilt angle is less than or equal to 45°, and the vertical component of the fan thrust is less than the vertical component of the wing lift. The fan also provides thrust when the UAV switches flight modes to ensure that the UAV's flight altitude remains constant during mode switching. By adopting a flying wing layout for the entire wing and placing a duct between the blended wing-body and the outer wing, with the duct size matched to the chord length of the outer wing, and integrating a high-efficiency fan within the duct, the propulsion system and wing structure are integrated into a unified design. The duct and fan no longer rely on additional tilting mechanisms or complex mechanical transmission structures, resulting in a clear structural hierarchy, compact configuration, and relatively light weight, which is beneficial for improving the thrust-to-weight ratio and overall reliability. Simultaneously, the integrated design of the duct and flying wing allows for deep structural integration of the propulsion unit and the load-bearing / lifting unit, laying the foundation for subsequent aerodynamic performance optimization and attitude control. The duct constrains and rectifies the airflow, effectively guiding the fan jet within the duct, significantly reducing radial diffusion losses. In dual-rotor flight mode, the flying wing layout combined with the ducted fan generates greater effective thrust, improving the thrust efficiency and thrust-to-weight ratio of the propulsion system, achieving high thrust density power output, and thus enhancing aerodynamic efficiency during vertical takeoff and landing and hovering. The ducted jet directly acts on the downstream aileron control surfaces, ensuring that the ailerons maintain significant control effectiveness even at low or near-zero airspeed conditions. This significantly improves the UAV's attitude control capabilities and accuracy during vertical takeoff and landing, hovering, and low-speed transitions. The ducted casing physically encapsulates the fan blades, enhancing flight safety and suppressing turbulence noise, thus giving the UAV superior acoustic stealth characteristics.

[0018] During flight mode switching, the ducted fan consistently serves as the primary power unit, providing controllable vertical thrust. As the UAV transitions from vertical takeoff and landing (VTOL) to horizontal cruise, the ducted fan continuously compensates for insufficient wing lift at large attitude angles. Combined with the large lift area and smooth aerodynamic shape of the flying wing configuration, this ensures that the vertical resultant force remains close to gravitational equilibrium during gradual attitude changes. This helps maintain a relatively constant altitude, avoiding significant descent or sudden climb, thus achieving a smooth transition between VTOL and fixed-wing flight modes and enhancing the stability and safety of the transitional flight.

[0019] In fixed-wing flight mode, the flying wing configuration, with its relatively large wing aspect ratio and integrated ducted fan and wing structure, creates a smooth and continuous fuselage shape, reducing abrupt changes and interference points. This allows almost the entire fuselage surface to contribute to lift generation. Compared to the traditional wing-plus-power-nacelle configuration, this configuration achieves a higher overall lift level, enabling the UAV to meet its cruise lift and thrust requirements at lower angles of attack and thrust conditions. The power system utilizes a high-thrust, high-efficiency ducted fan to provide horizontal thrust. Combined with the high lift-to-drag ratio of the flying wing configuration, it reduces average power consumption while maintaining flight speed and range, thus significantly improving endurance and mission coverage.

[0020] In summary, the ducted propulsion UAV proposed in this solution achieves significant improvements in structural compactness, vertical takeoff and landing performance, mode transition smoothness, horizontal flight aerodynamic efficiency, and noise control through the integrated design of flying wing layout and ducted propulsion. It provides an effective technical approach for UAV platforms that combine vertical takeoff and landing capabilities with efficient level flight performance. Attached Figure Description

[0021] Figure 1 This is one of the structural schematic diagrams of a ducted unmanned aerial vehicle provided in this application; Figure 2 This is the second structural schematic diagram of a ducted unmanned aerial vehicle provided in this application; Figure 3 A schematic diagram of the left middle wing of a ducted unmanned aerial vehicle (UAV) provided in this application; Figure 4 A schematic diagram of the structure of the left outer wing of a ducted unmanned aerial vehicle provided in this application; Figure 5 A schematic diagram of the structure of the left aileron of a ducted unmanned aerial vehicle provided in this application; Figure 6 A schematic diagram of the right middle wing of a ducted unmanned aerial vehicle (UAV) provided in this application; Figure 7 A schematic diagram of the right outer wing of a ducted unmanned aerial vehicle (UAV) provided in this application; Figure 8 A schematic diagram of the right aileron of a ducted unmanned aerial vehicle provided in this application; Figure 9 A schematic diagram of the carbon rod structure of a ducted unmanned aerial vehicle provided in this application.

[0022] Icons: 1. Upper section of left center wing; 2. Lower section of left center wing; 3. Left outer wing; 4. Upper section of right center wing; 5. Lower section of right center wing; 6. Right outer wing; 7. Left ESC; 8. Right ESC; 9. Left duct; 10. Right duct; 11. Tripod; 12. Battery compartment; 13. Left aileron; 14. Right aileron; 15. Left servo; 16. Right servo; 17. Flight control board; 18. Receiver; 19. Left winglet; 20. Right winglet; 21. First carbon rod; 22. Second carbon rod; 23. Third carbon rod; 24. Fourth carbon rod; 25. Fifth carbon rod; 26. Sixth carbon rod; 27. Seventh carbon rod; 28. Eighth carbon rod. Detailed Implementation

[0023] This application provides a ducted unmanned aerial vehicle (UAV), such as... Figure 1 and Figure 2 As shown, the system includes wings and ducts. The wings adopt a flying wing configuration and consist of a blended wing-body, outer wings, and ailerons located at the tail of the blended wing-body. The blended wing-body includes a left center wing and a right center wing. A left outer wing 3 is mounted on the left side of the left center wing, and a right outer wing 6 is mounted on the right side of the right center wing. Both the left outer wing 3 and the right outer wing 6 form reserved spaces with the blended wing-body. The left duct 9 and the right duct 10 are installed in their respective spaces, making the ducts and wings structurally integrated. The length direction of the duct is parallel to the length direction of the UAV. A fan capable of rotating around the length direction of the duct is installed inside the duct, and the fan is driven by a motor to achieve high-speed rotation. The left aileron 13 and the right aileron 14 are respectively hinged and movably mounted on the left and right sides of the trailing edge of the blended wing-body, respectively, and can rotate relative to the blended wing-body for aerodynamic control of the UAV's attitude in different flight modes. Through the above structural arrangement, the duct, fan, and wings form a compact integrated propulsion and lift system, providing a foundation for subsequent switching between dual-rotor and fixed-wing flight modes.

[0024] The duct runs along the length of the UAV, between the blended wing-body and the outer wing. The duct's inlet is flush with the wing root at the leading edge of the outer wing, and its outlet is flush with the wing root at the trailing edge. A fan and its drive motor are housed inside each of the two ducts. The fans in the left and right ducts rotate in opposite directions to counteract the counter-torque generated by the fan rotation, reducing overall aircraft attitude disturbance. The duct and fans form an integrated aerodynamic propulsion system. The inner wall of the duct constrains and guides the airflow, and during fan operation, it rectifies the high-speed airflow, reducing radial diffusion and leakage losses, thus converting more kinetic energy into effective thrust. Compared to traditional open-type propeller motors, ducted fans achieve greater thrust output and a higher thrust-to-weight ratio with the same power input, exhibiting higher thrust density—meaning greater thrust generated per unit volume. The duct casing physically encloses the high-speed rotating fan blades, preventing damage or safety hazards caused by exposed blades accidentally hitting obstacles. Furthermore, by optimizing the geometry of the duct inlet, constriction, and outlet, the jet structure is improved, reducing turbulence and vortex noise radiation, resulting in lower noise characteristics for the UAV. The fan jet exiting the duct directly acts on the aileron control surfaces, concentrating the airflow behind the ailerons and increasing its speed. This generates a larger aerodynamic torque even with a small control surface deflection angle, enhancing the UAV's attitude control capabilities at low or even zero speeds.

[0025] In this embodiment, the UAV has two operating modes: a dual-rotor flight mode and a fixed-wing flight mode. The thrust generated by the fan is always parallel to the length of the UAV, while the lift generated by the wings is perpendicular to the fan thrust. The UAV's tilt angle is defined relative to the ground coordinate system. When the UAV is in the vertical takeoff and landing, hovering, and low-speed lateral movement phases, the UAV's tilt angle relative to the ground is 90°. After the fans in the left and right ducts start, when the total thrust provided by the two sets of fans exceeds the UAV's weight, the UAV takes off. As the fan speed increases, the UAV accelerates vertically upward. This stage mainly relies on the vertical component of the fan thrust to balance and overcome gravity, which is the dual-rotor flight mode. When the UAV takes off vertically to a preset altitude, such as 50 m, and the altitude stabilizes, the left and right ailerons rotate downward synchronously, providing a nose-down torque. The UAV's attitude gradually tilts from 90° to 45°, and the wings gradually acquire a certain angle of attack and relative velocity. During this process, the vertical component of the wing lift gradually increases, but it is still less than the vertical component of the fan thrust, and the drone remains in dual-rotor flight mode.

[0026] When the drone's tilt angle is 45°, its horizontal forward speed is increased, for example, gradually increasing it to 15 m / s. As the horizontal speed increases, the effective speed of the wing relative to the incoming airflow increases, and the vertical component of the wing lift continuously increases. When the proportion of wing lift to the total vertical aerodynamic force reaches approximately 70%, and the proportion of fan thrust in the vertical direction drops to approximately 30%, the left and right ailerons rotate downwards synchronously, providing a nose-down torque, and the drone's attitude gradually transitions from 45° to 0°. During this attitude change, the fan continuously provides horizontal thrust to drive the drone's acceleration, the wing angle of attack remains within a safe range, and wing lift gradually replaces the vertical component of fan thrust as the main source of anti-gravity aerodynamic force, allowing the drone to smoothly switch from dual-rotor flight mode to fixed-wing flight mode. After completing the attitude transition, the drone enters a high-speed level flight phase, where fan thrust acts entirely in the horizontal direction, forming a continuous forward thrust. The wings generate sufficient lift to balance the drone's gravity at the corresponding angle of attack and incoming airflow speed, and the drone is in a typical fixed-wing flight mode.

[0027] During the transition from dual-rotor to fixed-wing flight mode, to ensure a smooth transition from vertical to horizontal attitude for the UAV and maintain a relatively constant altitude throughout the transition, the fan and wing must share the vertical aerodynamic forces at different stages. The wing's angle of attack for lift generation has an upper limit; in general designs, the maximum effective angle of attack does not exceed approximately 30°. Exceeding this angle easily leads to a stall zone, causing a sharp drop in lift. Therefore, in the transition range where the UAV's tilt angle decreases from 90° to approximately 30°, the wing has not yet established a sufficient boundary layer and vortex structure, making it difficult to provide sufficient lift. The power unit needs to provide additional thrust in the vertical direction to compensate for the insufficient lift. The ducted fan used in this application continuously jets downwards during this transition phase, generating a large vertical thrust component, effectively compensating for gravity, and ensuring the UAV maintains altitude stability during attitude changes without significant descent. Compared to traditional open-propeller power units, the ducted fan can maintain high efficiency and stronger thrust output even under high thrust and high load conditions, solving the problem of insufficient power during the wing tilt transition phase and ensuring a smooth transition between flight modes.

[0028] To ensure sufficient thrust reserve for the ducted fan UAV during vertical takeoff, landing, and hovering, this embodiment uses a Fengfan 70 mm 3060 / 2000KV 6S motor for the ducted fan. Each motor weighs approximately 280 g and, under appropriate battery voltage and current conditions, delivers a peak thrust of approximately 2700 N (or equivalent 2700 g force), providing a high thrust-to-weight ratio for small to medium-sized UAVs. To ensure stable operation of the motor under safe conditions, an 80 A Hobbywing Skywalker brushless ESC is used. The ESC weighs approximately 79 g and provides a continuous output current of 80 A and a short-term peak current of 100 A, meeting the current requirements of the ducted motor when operating near its maximum thrust. The power system is designed to match the total weight of the UAV with the vertical thrust required in dual-rotor flight mode. During vertical takeoff and landing (VTOL) and hovering, the two fans operate at no more than approximately 60% of their maximum thrust to counteract the UAV's weight and maintain maneuverability redundancy. The remaining 40% of thrust can be used to cope with gusts, rapid climbs, or attitude adjustments. In fixed-wing flight mode, the UAV primarily relies on wing lift to balance gravity, with the fans only providing horizontal thrust. During normal cruise, each fan outputs no more than approximately 40% of its maximum thrust to meet the requirements. Compared to traditional high-thrust operation throughout the flight, this effectively reduces energy consumption and increases endurance.

[0029] In summary, the ducted-wing UAV of this application adopts a flying wing layout for its entire wing, with a duct positioned between the blended wing-body and the outer wing. The duct size matches the chord length of the outer wing, and a high-efficiency fan is integrated within the duct, making the propulsion system and wing structure an integrated design. The duct and fan no longer rely on additional tilting mechanisms or complex mechanical transmission structures, resulting in a clear structural hierarchy, compact configuration, and relatively light weight, which is beneficial for improving the thrust-to-weight ratio and overall reliability. Simultaneously, the integrated design of the duct and flying wing allows for deep structural integration of the propulsion unit and the load-bearing / lifting unit, laying the foundation for subsequent aerodynamic performance optimization and attitude control. By constraining and rectifying the airflow through the duct, the fan jet is effectively guided within the duct, significantly reducing radial diffusion losses. In dual-rotor flight mode, the flying wing layout combined with the ducted fan can generate greater effective thrust, improving the thrust efficiency and thrust-to-weight ratio of the propulsion system, achieving high thrust density power output, and thus enhancing aerodynamic efficiency during vertical takeoff and landing and hovering. The ducted jet directly acts on the downstream aileron control surfaces, ensuring that the ailerons maintain significant control effectiveness even at low or near-zero airspeed conditions. This significantly improves the UAV's attitude control capabilities and accuracy during vertical takeoff and landing, hovering, and low-speed transitions. The ducted casing physically encapsulates the fan blades, enhancing flight safety and suppressing turbulence noise, thus giving the UAV superior acoustic stealth characteristics.

[0030] During flight mode switching, the ducted fan consistently serves as the primary power unit, providing controllable vertical thrust. As the UAV transitions from vertical takeoff and landing (VTOL) to horizontal cruise, the ducted fan continuously compensates for insufficient wing lift at large attitude angles. Combined with the large lift area and smooth aerodynamic shape of the flying wing configuration, this ensures that the vertical resultant force remains close to gravitational equilibrium during gradual attitude changes. This helps maintain a relatively constant altitude, avoiding significant descent or sudden climb, thus achieving a smooth transition between VTOL and fixed-wing flight modes and enhancing the stability and safety of the transitional flight.

[0031] In fixed-wing flight mode, the flying wing configuration, with its relatively large wing aspect ratio and integrated ducted fan and wing structure, creates a smooth and continuous fuselage shape, reducing abrupt changes and interference points. This allows almost the entire fuselage surface to contribute to lift generation. Compared to the traditional wing-plus-power-nacelle configuration, this configuration achieves a higher overall lift level, enabling the UAV to meet its cruise lift and thrust requirements at lower angles of attack and thrust conditions. The power system utilizes a high-thrust, high-efficiency ducted fan to provide horizontal thrust. Combined with the high lift-to-drag ratio of the flying wing configuration, it reduces average power consumption while maintaining flight speed and range, thus significantly improving endurance and mission coverage.

[0032] In summary, the ducted propulsion UAV proposed in this solution achieves significant improvements in structural compactness, vertical takeoff and landing performance, mode transition smoothness, horizontal flight aerodynamic efficiency, and noise control through the integrated design of flying wing layout and ducted propulsion. It provides an effective technical approach for UAV platforms that combine vertical takeoff and landing capabilities with efficient level flight performance.

[0033] Furthermore, a flight control board 17 is installed inside the blended wing-body structure. The flight control board 17 is electrically connected to the fans, motors, ESCs, tail aileron servos, and batteries in the left and right side ducts via cables. It is also connected to the receiver 18, pitot tube, attitude sensor, and GPS module. The flight control board 17 collects parameters such as the UAV's current attitude angle, horizontal forward speed, and the speed and current of each motor. It estimates the vertical component of the fan thrust based on the fuselage tilt angle and motor output thrust, and estimates the vertical component of the wing lift by combining airspeed and wing angle of attack. The flight control board 17 determines the current aerodynamic support mode based on the vertical force ratio of both the fan and the drone's horizontal forward speed. When the vertical fan thrust accounts for a high proportion and the horizontal forward speed is below a preset threshold, it is determined to be in dual-rotor flight mode. When the vertical lift of the wing gradually increases and exceeds the preset proportion, and the horizontal forward speed reaches or exceeds the critical speed required for fixed-wing cruise, the left and right ailerons are controlled to rotate downward synchronously, providing the drone with a pitching torque, allowing the drone's attitude to transition from a large tilt angle to a near-zero horizontal attitude, achieving a smooth switch from flight mode to fixed-wing flight mode. Conversely, in fixed-wing flight mode, if a significant decrease in horizontal forward speed is detected or the vertical component of the wing lift is insufficient to balance gravity, the flight control board 17 increases the fan thrust and controls the left and right ailerons to rotate upward synchronously, providing the drone with a pitching torque, adjusting the aircraft attitude, gradually increasing the vertical component of the fan force, and guiding the drone back to dual-rotor flight mode, thereby ensuring a safe aerodynamic margin is maintained under complex operating conditions.

[0034] In this embodiment, the flight control board 17 adopts the Radiolink F722 rotorcraft flight controller. This flight controller is based on an M7 architecture processor with a main frequency of 216 MHz, possessing high command processing capability and data processing bandwidth. It can complete attitude calculation, state estimation, and multi-axis servo control calculations within a short control cycle, achieving real-time and precise adjustment of the dual-ducted fan speed and aileron deflection angle. The Radiolink F722 integrates an OSD module, which can overlay flight mode information onto the image signal for output, facilitating intuitive observation of key parameters such as the UAV's flight mode, attitude angle, airspeed, fan output power, and remaining battery power at ground stations or image transmission terminals. The onboard 128MB memory acts as a black box, recording sensor data, control commands, and mode switching times during flight for extended periods, providing a basis for subsequent parameter calibration, control law optimization, and flight fault analysis.

[0035] The Radiolink F722 flight controller features multiple PWM and serial interfaces, enabling simultaneous connection to multiple ESCs and servos. It is compatible with various ESC signals and throttle protocols, facilitating unified management of the ducted fan power system and aileron servo mechanism. This flight controller can be paired with an M8N TS100 GPS module to provide the UAV with high-precision position and speed information, enabling functions such as hovering, flight path planning, and return-to-home in case of loss of control. Simultaneously, the flight controller supports ESC telemetry signal access, allowing real-time acquisition of motor current, voltage, and speed, enabling monitoring and protection of the power system's health. By appropriately setting flight modes and threshold conditions in the flight control software, the flight control board 17 can control the UAV to transition from dual-rotor flight mode to fixed-wing flight mode or vice versa, based on preset logic, when it detects that the vertical components of fan thrust and wing lift meet the switching conditions. During the entire transition process, it dynamically adjusts thrust output and control surface deflection to maintain stable pitch, roll, and yaw attitudes.

[0036] Through the aforementioned structure and control strategy, the flight control board 17 in this ducted unmanned aerial vehicle (UAV) not only achieves conventional attitude stabilization and trajectory control, but more importantly, it makes real-time judgments on the aerodynamic support state of the UAV based on the ratio of the vertical component of fan thrust to the vertical component of wing lift and the horizontal forward speed, and actively completes the intelligent switching between dual-rotor flight mode and fixed-wing flight mode. Leveraging the powerful computing capabilities, rich interface resources, and comprehensive data recording and image transmission display functions of the Radiolink F722, the UAV maintains a more stable attitude and altitude during vertical takeoff and landing, hovering, transition tilt, and level flight cruise. Altitude loss during flight mode switching is significantly reduced, improving flight safety margin and controllability. Simultaneously, it facilitates continuous improvement of the overall control performance and reliability through data playback and parameter optimization.

[0037] Furthermore, in dual-rotor flight mode, the flight control board 17 uses the differential thrust of the ducted fans and the aerodynamic forces of the aileron control surfaces as actuators to decouple the roll, pitch, and yaw attitudes of the UAV. Specifically, the flight control board 17 controls the asynchronous rotation of the fans in the left and right ducts to adjust the roll attitude of the UAV. That is, by changing the speed difference between the left and right fans, a pair of thrusts of different magnitudes are generated, causing the UAV to generate a roll torque around the longitudinal axis. For example, when the speed of the left fan is greater than that of the right fan, the thrust on the left is greater than that on the right, and the UAV tends to roll to the right; when the speed of the right fan is greater than that of the left fan, the UAV tends to roll to the left. For the yaw attitude, the flight control board 17 controls the ailerons on the left and right sides to rotate synchronously in opposite directions to adjust the yaw attitude of the UAV. By changing the deflection direction and angle of the ailerons on both sides, an asymmetrical aerodynamic force distribution is formed, thereby generating a yaw torque. For example, when the left aileron 13 deflects forward and the right aileron 14 deflects backward, the aerodynamic forces at the tail create a resultant moment in the plane, causing the entire aircraft to yaw to the left; if the left aileron 13 deflects backward and the right aileron 14 deflects forward, the entire aircraft yaws to the right. For pitch attitude, the flight control board 17 controls the left and right ailerons to rotate synchronously in the same direction, changing the overall lift distribution at the tail and thus generating a pitch moment around the lateral axis. For example, when the left aileron 13 and right aileron 14 deflect upward simultaneously, a downward component force is generated at the tail, causing the nose to lift and increasing the overall pitch angle; when the left and right ailerons deflect downward simultaneously, the force on the tail changes, the nose to press down, and the overall pitch angle decreases. Through the above control methods, in the dual-rotor flight mode where the wing lift is insufficient to provide complete attitude control, precise adjustment of the UAV's three-axis attitude can be achieved by relying on the differential thrust of the ducted fan and the aileron aerodynamic forces under the concentrated jet flow.

[0038] In fixed-wing flight mode, as the UAV's horizontal forward speed increases, the wings acquire stable aerodynamic lift and boundary layer structure. The flight control board 17 adjusts the functional allocation of each actuator accordingly, making the control method more consistent with the aerodynamic layout characteristics of a fixed wing. In this mode, the flight control board 17 controls the asynchronous rotation of the fans in the left and right ducts to adjust the UAV's yaw attitude. By changing the speed difference between the left and right fans, asymmetrical thrust is generated in the horizontal direction, thus producing a yaw moment. For example, when the left fan speed is greater than the right fan speed, the left thrust is greater, and the entire nose of the UAV yaws to the right; when the right fan speed is greater than the left fan speed, the entire nose yaws to the left. For roll attitude control, the flight control board 17 controls the ailerons on both sides to rotate synchronously in opposite directions to adjust the UAV's roll attitude, creating differential lift by changing the lift distribution at the trailing edges of the wings. For example, when the left aileron 13 deflects upward and the right aileron 14 deflects downward, the lift of the left wing decreases and the lift of the right wing increases, resulting in a leftward roll. When the left aileron 13 deflects downward and the right aileron 14 deflects upward, the aircraft rolls to the right. In terms of pitch attitude control, the flight control board 17 controls the left and right ailerons to rotate synchronously in the same direction to adjust the UAV's pitch attitude. For example, when the left aileron 13 deflects upward and the right aileron 14 deflects upward, the overall lift at the tail decreases, the nose rises, and the overall pitch angle increases. When both ailerons deflect downward simultaneously, the lift at the tail increases, the nose falls, and the overall pitch angle decreases. Through the above control logic, the ailerons operate in the same manner as in conventional fixed-wing aircraft in fixed-wing flight mode, while the ducted fan, while maintaining propulsion, undertakes yaw control through differential output, which is beneficial for maintaining the efficiency and coordination of attitude control under high-speed cruise conditions.

[0039] By setting different roles for the ducted fan and ailerons in roll, pitch, and yaw channels in both dual-rotor and fixed-wing flight modes, the flight control board 17 can adaptively select control strategies based on the flight mode, allowing the differential thrust of the ducted fan and the aileron control surface deflection to leverage their respective advantages under different operating conditions. In dual-rotor flight mode, the rapid response of the ducted fan thrust is utilized to achieve direct roll control, while the high efficiency of the control surfaces under concentrated jet flow is used to achieve yaw and pitch adjustments at low speeds, ensuring attitude stability and maneuverability during vertical takeoff and landing and hovering. In fixed-wing flight mode, the efficient aerodynamic control capabilities of the wings and ailerons in high-speed airflow are fully utilized, with roll and pitch control primarily handled by the ailerons, while yaw correction is achieved using the differential thrust of the ducted fan, thus ensuring the reliability of heading control. The above control method forms a clear and coherent control channel allocation between different flight modes, which not only avoids the coupling problem caused by the functional confusion of the same actuator in different modes, but also improves the accuracy and response speed of attitude control throughout the entire flight envelope, which is conducive to realizing continuous and stable flight of ducted unmanned aerial vehicles from vertical take-off and landing, transition tilting to horizontal cruise.

[0040] Furthermore, each of the two flight modes of the UAV corresponds to a separate flight parameter document. The flight parameter document is stored in the non-volatile memory of the flight control board 17, and includes the hybrid control matrix configuration for each mode, PID control parameters for attitude and altitude control, rudder limits, throttle curves, and related filter parameters. The flight parameter document for the dual-rotor flight mode is specifically optimized for the aerodynamic characteristics where the ducted fan is the primary source and the wing lift is secondary, focusing on the control requirements under large attitude angles, low airspeeds, and concentrated jet thrust. The flight parameter document for the fixed-wing flight mode is configured based on the aerodynamic characteristics of a fixed wing, emphasizing the pitch, roll, and yaw control quality under conditions where wing lift is dominant and the ducted fan provides horizontal thrust.

[0041] In dual-rotor flight mode, the hybrid control logic primarily allocates the speed difference between the left and right ducted fans to the roll channel, the synchronous yaw of the ailerons to the pitch channel, and the synchronous counter-yaw of the ailerons to the yaw channel. The corresponding PID parameters are set to suit low-speed, large-attitude-angle flight, ensuring rapid response and moderate damping of the control system during hovering, vertical takeoff and landing, and low-speed maneuvers. In fixed-wing flight mode, the hybrid control logic is adjusted. The roll channel is primarily mapped to the synchronous counter-yaw of the ailerons, and the pitch channel is primarily mapped to the synchronous yaw of the ailerons. The differential thrust of the ducted fans is used for yaw correction, and the PID parameters are tuned according to the level flight characteristics of fixed-wing aircraft to ensure good flight stability and smooth handling during medium-to-high-speed cruise, turns, and climbs / descents. By storing and configuring the hybrid control relationships and PID parameters separately for different modes, the flight control board 17 can provide matching control laws for two distinctly different aerodynamic operating states.

[0042] Furthermore, a unified mode switching channel is set up in the flight control board 17 for the two flight modes mentioned above. This switching channel can be controlled by a three-position switch or a multi-position lever on the remote controller, corresponding to the three areas of vertical flight, transition, and level flight. The flight control board 17 reads the current state of the switching channel in real time and switches between the dual-rotor flight parameter document and the fixed-wing flight parameter document in an orderly manner according to the state change. When the channel is in the intermediate transition position, the flight control board 17 adopts a hybrid control strategy, interpolating or gradually changing the key parameters in the two sets of flight parameters (such as hybrid control ratio, PID gain, angular velocity limit, rudder limit, etc.) to make the control law transition smoothly in numerical terms, rather than abruptly changing. At the same time, the flight control board 17 introduces ramp limiting and filtering processing between attitude commands, throttle commands and actual outputs to keep the changes of executed quantities such as ducted fan thrust and aileron deflection angle continuous and predictable during the transition process.

[0043] Specifically, during the phase where the UAV climbs vertically to the predetermined mission altitude using a dual-rotor configuration, the flight control board 17 is in self-stabilizing mode, automatically maintaining the UAV's attitude and altitude stability based on data from attitude sensors, barometers, and GPS. Once the UAV reaches the set mission altitude, the operator switches the flight control mode from self-stabilizing to manual mode via the remote controller. At this point, throttling, attitude control, and mode switching are directly controlled by the operator. Subsequently, the operator moves the transition switch lever, sending a command to the flight control board 17 to transition from dual-rotor to fixed-wing. The flight control board 17, based on this command, controls the UAV to tilt to approximately 45°, coordinating the ducted fan thrust and aileron deflection during the tilt, allowing the UAV to gradually establish a certain horizontal forward speed while maintaining a relatively constant altitude. Once the aircraft's attitude reaches the transition angle and the airspeed meets the level flight requirements, the operator continues to move the level flight lever. Upon receiving the level flight mode command, the flight control board 17 switches the flight mode from dual-rotor to fixed-wing, adjusting the control law to make wing lift the primary source of anti-gravity aerodynamic power. After completing the attitude and control mode switching, the operator switches the flight control mode from manual mode back to self-stabilizing mode. At this time, the flight control board 17 takes over the attitude and trajectory control according to the fixed-wing control logic, and the UAV flies stably in a fixed-wing manner.

[0044] During the transition from level flight mode to vertical flight mode, the UAV initially operates in fixed-wing level flight mode, with the flight control board 17 maintaining pitch, roll, and yaw stability in self-stabilizing mode. When vertical landing or hovering is required, the operator first reduces the fan motor throttle to decelerate the UAV and switches the flight control mode from self-stabilizing to manual, giving the pilot direct control over attitude and thrust. Based on this, the operator moves the transition switch to trigger the flight control system to transition from fixed-wing to dual-rotor mode. The flight control board 17 controls the UAV to gradually increase its pitch angle, tilting the aircraft to approximately 45°, while simultaneously reducing the wing lift contribution in the vertical direction and gradually increasing the ducted fan vertical thrust component, ensuring controllable altitude changes during deceleration and attitude alteration. When the aircraft's attitude reaches the set transition angle and the horizontal speed drops below the corresponding threshold, the operator moves the vertical flight control stick. The flight control board 17 switches the control law to dual-rotor control logic according to the vertical flight mode command, allowing the ducted fan thrust to undertake the primary anti-gravity task in the vertical direction, while wing lift plays a secondary role. After completing the vertical flight mode switch, the operator switches the flight control mode back from manual to self-stabilizing mode, where the flight control takes over attitude and altitude control. The UAV then achieves vertical flight, hovering, or slow descent using a dual-rotor configuration.

[0045] Furthermore, a left servo 15 and a right servo 16 are mounted on the blended wing-body, located near the hinge axes of the left and right ailerons, respectively. The left servo 15 and right servo 16 are fixed to the internal reinforcing structure of the blended wing-body with screws, and their control arms are connected to the corresponding ailerons via linkage mechanisms, allowing each aileron to rotate independently relative to the blended wing-body. Through this one-servo-one-wing arrangement, the flight control board 17 can output independent control signals to the left servo 15 and right servo 16, thereby achieving synchronous yaw of the left and right ailerons in the same direction or synchronous yaw in opposite directions. Combined with the aforementioned control strategy, these ailerons perform pitch, roll, and yaw control functions in different flight modes, improving maneuverability and providing a hardware foundation for differential and redundant control.

[0046] In this embodiment, the aileron drive servo is a PTK7452MGG-D 9g digital metal gear servo. This servo uses PWM pulse width modulation signal control, with a center pulse width of approximately 1520 μs and an operating frequency of approximately 333Hz. It can directly match the standard servo output channel of the aforementioned flight control board 17, facilitating the output of precise control surface commands at a high refresh rate. The servo's operating voltage range is DC 4.8 V to 7.4 V, compatible with the UAV's main power supply or independent BEC regulated output, maintaining stable output torque under different power supply schemes. Its stall torque is approximately 2.8 kg·cm to 4.5 kg·cm. Considering the aileron area, maximum deflection angle, and dynamic pressure level within the flight envelope, this torque margin can meet the maximum control load requirements of the aileron under the concentrated jet action of the dual-rotor flight mode and the high-speed level flight mode of the fixed wing, ensuring reliable control surface drive force even under extreme conditions. The servo employs a metal gear transmission structure, coupled with a core motor as the drive motor, featuring strong impact resistance, good gear wear resistance, and high output angle repeatability. The overall dimensions of the servo are approximately 23.6 mm × 11.8 mm × 21.3 mm, and its individual weight is approximately 12 g. While providing sufficient torque, it occupies minimal space and is lightweight, which helps maintain a compact internal layout of the blended wing-body and a reasonable distribution of the aircraft's center of gravity. Through the aforementioned servo configuration and selection, this ducted unmanned aerial vehicle (UAV) achieves independent and precise actuation of the left and right ailerons while ensuring the torque requirements of the aileron control surfaces, providing reliable actuator support for high-frequency attitude adjustments and mode switching in complex flight modes.

[0047] Furthermore, the leading edge of the outer wing is configured with a swept-back layout, with a sweep angle of 20° to 30°, preferably 25°. With a swept-back arrangement at a certain angle, the incoming airflow on the wing surface no longer flows solely along the chord direction, but generates a significant spanwise component, resulting in a more uniform airflow distribution along the span of the outer wing. When the UAV experiences yaw disturbances, the swept-back outer wing will generate self-drag characteristics under the change in relative airflow direction, effectively increasing the directional damping coefficient and causing the angular velocity of the fuselage around the vertical axis to decay more quickly. Through this aerodynamic layout design, the yaw angle deviation of the UAV under the influence of crosswinds, gusts, or attitude disturbances is reduced, and the recovery process is smoother. This significantly improves the anti-interference capability and directional stability in the yaw direction, providing a more sufficient directional stability margin for mode switching between dual-rotor and fixed-wing flight modes.

[0048] Furthermore, the batteries required for the power system are installed in the battery compartment 12 at the head of the blended wing-body fuselage, placing the larger mass batteries in the forward region of the fuselage and structurally shifting the overall center of gravity of the UAV forward. Through the integrated arrangement of the batteries with components such as the flight control system, ducted fan, electronic speed controller, servos, and wings, the center of gravity of the UAV is positioned at 8% to 12% of the mean aerodynamic chord ahead of the UAV's focal point, forming an aerodynamic-mass layout with static stability margin. When the UAV's pitch attitude deviates, the wings and tail ailerons can automatically generate restoring moments under this center of gravity arrangement, causing the pitch angle deviation to naturally decrease without external control, thus achieving a statically stable layout. Based on the above matching of the center of gravity position and aerodynamic characteristics, the overall pitch damping ratio is optimized to approximately 0.35 to 0.45. Within this damping range, the UAV will not experience prolonged large oscillations after being subjected to pitch disturbances, while maintaining a certain degree of maneuverability. In conjunction with the aforementioned flight control law, during the transition from dual-rotor flight mode to fixed-wing flight mode or vice versa, the pitch angle fluctuation of the UAV can be controlled within ±3°. The attitude change process is continuous and smooth, which helps to reduce altitude fluctuations and sudden overload, and improves the safety and comfort of the mode switching process.

[0049] In this implementation, a 6S-format lithium battery, compatible with the ducted power system and flight control board 17, is selected. It has a nominal voltage of 22.2 V, a capacity of 2700 mAh, and a discharge rate of 30C. Under rated operating voltage and discharge rate conditions, this battery can provide stable power output to the two ducted fans and avionics, meeting the power requirements of the UAV during vertical takeoff and landing, transitional flight, and fixed-wing cruise phases. The battery's dimensions are approximately 52.5 mm × 36 mm × 108 mm, and its weight is approximately 380 g. Combined with the structural design of the internal mounting bay in the nose, the center of gravity can be finely adjusted through reasonable installation, ensuring the overall center of gravity remains stably within the target range before the focal point. Through the above battery parameter selection and pre-positioning method, this implementation achieves a coordinated design of mass distribution and aerodynamic center while meeting the power and charge requirements, providing crucial support for the UAV to maintain good static stability and pitch damping characteristics throughout its flight envelope.

[0050] In long-term engineering practice, the wind resistance performance of vertical takeoff and landing (VTOL) UAVs, especially during the descent phase, has consistently been difficult to meet requirements, resulting in a small flight safety margin. The fundamental reason is that the airflow structure around the UAV's wings differs significantly from that of a conventional fixed-wing aircraft during level flight. At higher descent speeds, a reverse airflow from the tail to the nose appears locally on the wing surface, causing the actual aerodynamic force generated by the ailerons to be opposite to the design expectation—a phenomenon known as aileron reversal. When the wing descends at a vertical or high angle of attack, the flow field near the wing's trailing edge becomes even more sensitive. If crosswinds or gusts are simultaneously added, the aileron reversal phenomenon is further amplified, causing the pilot's or flight control board's input to be opposite to the aircraft's response. This leads to increased pitch, roll, and yaw coupling, significantly reducing flight stability.

[0051] To address this issue, this application optimizes the structure and airflow channels of the ailerons. Specifically, the left aileron 13 is a continuous, integrated structure along the width of the UAV, functionally divided into a first wing segment located in the trailing edge region of the left outer wing 3 and a second wing segment located in the trailing edge region of the left duct 9 exhaust outlet. Similarly, the right aileron 14 is a continuous, integrated structure along the width of the UAV, functionally divided into a first wing segment located in the trailing edge region of the right outer wing 6 and a second wing segment located in the trailing edge region of the right duct 10 exhaust outlet. The first wing segment is basically aligned with the trailing edge of the corresponding outer wing in planar projection and is mounted on the trailing edge of the blended wing-body via a hinged structure, mainly located in the mainstream area behind the outer wing; the second wing segment is located in the trailing edge region covered by the corresponding duct jet, corresponding to the high-energy jet channel downstream of the duct exhaust outlet. The first and second wing segments are structurally integrated and driven by the same servo to achieve unified deflection, but their airflow environments along the span are significantly different, thus forming a division of labor between a stable airflow zone and an airflow interference zone in the flow field structure.

[0052] During normal vertical takeoff and landing or low-speed descent, the airflow around the UAV mainly flows from the nose to the tail. The flow field near the boundary layer and trailing edge of the wing is relatively regular. The airflow near the first and second wing sections is predominantly positive. The aerodynamic force generated by the deflection of the ailerons is consistent with the set control effect, providing reliable pitch, roll, and yaw control for the flight control board 17. When the descent speed increases to a certain extent, the local airflow on the upper surface of the wing, especially near the trailing edge, exhibits significant upward scouring and backflow components due to the combined effect of inertia and gravity, forming a reverse airflow region from the tail to the nose. This reverse airflow concentrates on the middle and rear sections of the wing's trailing edge, easily interfering with the aileron control surface flow field. This can cause the aileron's aerodynamic force direction to reverse or its control effect to weaken in this region, thus triggering the aileron reversal problem.

[0053] In this embodiment, the duct serves as a power unit, installed between the blended wing-body and the outer wing. When the fan inside the duct operates, a portion of the airflow flowing from the nose to the tail of the UAV is intercepted by the duct structure, accelerated by the fan inside the duct, and then ejected at a high speed from the duct outlet, forming a directional high-speed jet stream from front to back. After exiting the duct, this jet stream covers the first wing section downstream of it, forming a stable airflow zone with high dynamic pressure and stable direction above the first wing section; while the area where the second wing section is located is partially exposed to the reverse flow or turbulent flow formed during descent, forming an airflow interference zone. Thus, during vertical or steep descent, even if there is a local reverse airflow from the tail to the nose in the large-scale external flow field, the ducted jet stream still maintains a forward airflow direction from the nose to the tail on the first wing section.

[0054] Because the aileron is a continuous control surface, the airflow stability zone where the first section is located maintains a positive airflow. After the aileron deflects, the aerodynamic force generated in this region does not reverse direction, still providing pitch, roll, and yaw control moments according to the design direction. While the airflow interference zone where the second section is located may be affected by some reverse airflow, its span is relatively reduced, no longer covering the entire aileron span. Thus, the interference area of ​​the reverse airflow on the aileron is significantly reduced, and the aileron effect is mainly confined to a local area near the second section, while the first section still plays a dominant control role. Under the combined effect, the resultant force and resultant moment generated by the aileron as a whole remain consistent with the expected command direction, effectively weakening the aileron effect phenomenon.

[0055] Under conditions of crosswind interference, the ducted jet has high dynamic pressure and good directionality, which can form a strong airflow stabilization zone on the first wing section, offsetting part of the distortion of the local flow field by the lateral flow and further suppressing the reverse or fluctuation of the aileron control effect. From the perspective of attitude control, even under conditions of large descent rate and crosswind superposition, the effective control effect of the aileron on the first wing section can still provide the flight control board 17 with a predictable and linearly approximate control response, making the control law design simpler and the control margin larger, avoiding the output saturation or frequent correction of the control system due to sudden reverse of the control effect.

[0056] Through the aforementioned aileron partitioning and ducted jet co-design, the high thrust density and concentrated airflow characteristics of the ducted fan are utilized to create a reasonable distribution of stable and disruptive airflow zones along the aileron span, significantly reducing the effective interference area of ​​the reverse airflow on the aileron during descent. Furthermore, the reverse effect of the aileron is significantly weakened under high descent rates in traditional vertical takeoff and landing flying-wing UAVs, making the aileron's aerodynamic response more stable and controllable throughout the entire flight envelope. This design not only improves the UAV's handling stability and wind resistance during descent but also enhances the robustness of the flight control board 17 in vertical takeoff and landing, hovering, and transition control strategies, providing crucial protection for the safe operation of the entire aircraft under complex weather conditions.

[0057] Furthermore, the wing also includes a left winglet 19 located at the wingtip of the left outer wing 3 and a right winglet 20 located at the wingtip of the right outer wing 6. These winglets, working in conjunction with the outer wing airfoil and sweep angle, effectively reduce wingtip vortex intensity, decrease induced drag, and improve the lift-to-drag ratio during level flight and turns. Simultaneously, the winglets enhance airflow adhesion in the wingtip region to a certain extent, enabling the wing to maintain good lift characteristics and directional stability even at larger angles of attack and under crosswind disturbances. This provides support for the UAV's economical cruise and long-endurance performance in fixed-wing flight mode.

[0058] Furthermore, the wings are made of ABS printing material and formed using 3D printing technology. For example... Figures 3 to 8As shown, the left center wing is divided into upper left center wing section 1 and lower left center wing section 2, which are printed separately; the right center wing is divided into upper right center wing section 4 and lower right center wing section 5, which are printed separately; the left outer wing 3 and right outer wing 6 are printed separately; the left aileron 13 and right aileron 14 are printed separately; and the left winglet 19 and right winglet 20 are also printed separately. After the upper left center wing section 1 and lower left center wing section 2 are printed and the electrical components are arranged, they are assembled into the overall structure of the left center wing using mortise and tenon joints and threaded connections; the upper right center wing section 4 and lower right center wing section 5 are assembled into the right center wing in the same way. The left outer wing 3, right outer wing 6, left aileron 13, right aileron 14, left winglet 19, and right winglet 20 are all independently printed parts, which can be disassembled or installed as needed, facilitating transportation and maintenance, and also enabling rapid iterative optimization of subsequent local structural parameters. 3D printing technology enables the creation of complex curved surfaces, internal reinforcing ribs, and hollow structures in a single molding process, avoiding the impact of accumulated assembly errors from multiple processes in traditional manufacturing. This significantly breaks through the limitations of traditional manufacturing processes in terms of structural complexity and integrated molding.

[0059] like Figure 9 As shown, in terms of load-bearing structure, eight carbon rods are installed inside the wing as the main load-bearing components. The first carbon rod 21 and the second carbon rod 22 penetrate the wing-body blend, undertaking the structural connection and main load-bearing functions of the wing-body blend, and are used to improve the stiffness and bending strength of the midwing region. The third carbon rod 23 to the sixth carbon rod 26 are respectively located in the connection area between the wing-body blend and the left outer wing 3 and the right outer wing 6. One side is connected to the internal reinforcing rib of the wing-body blend, and the other side extends into the interior of the outer wing, providing reliable shear and bending support for the connection between the wing-body blend and the outer wing, so that the wing section connection maintains structural integrity and shape stability under heavy load maneuvers and gusts. The seventh carbon rod 27 and the eighth carbon rod 28 penetrate the left and right ailerons, respectively serving as the rotation axis of the corresponding ailerons. The servo motor pulls the aileron around the corresponding carbon rod through the linkage to achieve the same or opposite deflection of the aileron, ensuring the stiffness and durability of the control surface rotation axis. The aforementioned carbon rod, together with the ABS printed skin and internal ribs, forms a "carbon rod-printed skin" combined structure, which significantly improves the overall mechanical performance of the wing while maintaining the overall lightweight design.

[0060] The various printed components are primarily connected by threads, facilitating quick assembly and disassembly while ensuring connection strength, making them suitable for on-site maintenance and component replacement. The duct is secured to the outer wing and blended wing-body using bolts and nuts. The duct's installation position facilitates the disassembly and maintenance of the fan, motor, and ESC, while also providing a reliable rigid connection along the stress path, ensuring the duct does not experience significant displacement or deformation under high thrust conditions. A triangular support 11 is installed in the middle of the tail section of the blended wing-body. This support 11 is connected to the blended wing-body via reinforcing ribs, providing three-point support for the wing during takeoff, landing, or ground storage. Together with the nose and wingtip support points, it ensures the UAV maintains a stable vertical parking position on the ground, preventing skin damage or tipping due to wing contact with the ground.

[0061] To further reduce structural weight while reserving space for internal wiring and installation, numerous hollow structures are designed on internal structural components such as wing ribs. This allows for appropriate thinning or removal of material in non-load-bearing areas, retaining only necessary reinforcing ribs and load transfer paths, thereby reducing the wing's weight and providing reasonable routing channels for power, signal, and transmission lines. The triangular support 11 and ailerons also employ hollow designs to reduce weight while meeting stiffness and strength requirements. Considering the fatigue strength requirements of key load-bearing components, wall thickness and local reinforcing ribs are added at critical structural locations such as wing surface connections, duct-wing connection areas, and servo mounts, forming locally thickened and stiffened structures to ensure sufficient structural strength and stiffness during multiple takeoffs and landings, high-load maneuvers, and abnormal attitude recovery. The wing skin uses a 3D-printed shell with a thickness of approximately 0.5 mm. Through the collaborative work of the skin, internal ribs, and carbon rods, overall bending and torsional resistance is improved while reducing weight.

[0062] During the wing structure design phase, mounting bays for electrical components such as servos, batteries, power units, ESCs, and flight control boards (17) are pre-arranged within the blended wing-body and each wing section. Each bay is connected to the external skin via reinforcing ribs, providing a reliable mounting foundation for the electrical components and ensuring that related components do not loosen or shift during flight. The battery compartment (12) is located at the front of the blended wing-body, facilitating a forward shift of the center of gravity. The ducted motor mounting bay is located inside the duct, the left ESC (7) bay is located to the right of the left duct (9), and the right ESC (8) bay is located to the left of the right duct (10). The flight control board (17) is mounted slightly above the center of the fuselage to reduce the transmission of high-frequency vibrations. The servo mounting base is aligned with the aileron pivot, ensuring a reasonable arrangement of the servo output and control surface lever arms. By reserving mounting positions during the design phase, the center of gravity, volume, and wiring requirements of each component are uniformly coordinated, giving the UAV a stable structural layout and center of gravity position when installed.

[0063] In this embodiment, the overall length of the UAV is approximately 450 mm, and the wingspan is approximately 1200 mm. The fill density of the enclosed internal filling area is set to approximately 3%. The fill density is minimized while ensuring structural rigidity and strength to reduce material usage and airframe weight. The total weight of the entire aircraft, including all electrical components (including battery, ducted motor, ESC, servo motor, flight control, GPS, and image transmission, etc.), is approximately 1.6 kg. Combined with the aforementioned high thrust-density ducted propulsion system, the UAV has a high thrust-to-weight ratio during vertical takeoff and landing, hovering, and fixed-wing cruise phases, providing sufficient power redundancy for complex flight missions.

[0064] During flight testing, the ducted fan UAV demonstrated excellent attitude stability and control response during vertical takeoff. When the ducted fan thrust reached approximately 40% of its maximum thrust, the UAV achieved stable takeoff and entered a vertical climb, indicating a reasonable match between the propulsion system and the overall aircraft mass, with sufficient thrust margin for vertical takeoff. In multiple field test flights, the UAV exhibited precise attitude control during vertical takeoff and landing, with smooth hovering and ascent / descendance, and minimal attitude fluctuations in gust winds. After climbing to approximately 50 meters, the flight control system smoothly transitioned from vertical takeoff mode to horizontal cruise mode, with controllable altitude changes and continuous attitude changes during the transition. After completing the first lap of the flight path, only about 17% of the battery power was consumed, reflecting the UAV's high aerodynamic efficiency and energy utilization in fixed-wing level flight mode.

[0065] In subsequent tests, the UAV further demonstrated high mode-switching flexibility. Even at a low altitude of approximately 5 meters, it could rapidly transition from vertical hovering or low-speed vertical flight mode to level flight mode under flight control commands, exhibiting timely attitude response and continuous maneuvers without significant altitude drops or attitude changes. During level flight, the overall power consumption remained low, with the ducted propulsion system primarily outputting power for horizontal propulsion, while wing lift handled the majority of anti-gravity tasks. This demonstrated the low-energy consumption advantage of combining the wing configuration with ducted propulsion. Flight test results showed that this embodiment achieved the expected design goals in terms of vertical takeoff and landing stability, mode-switching smoothness, energy utilization during cruise, and overall lightweight design, providing reliable engineering verification for the application of ducted UAVs in long-endurance, complex environmental mission scenarios.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A ducted unmanned aerial vehicle (UAV), characterized in that, It includes wings and ducts. The wings include a blended wing-body, outer wings and ailerons. Outer wings are installed on the left and right sides of the blended wing-body. Ailerons are movably installed at the tail of the blended wing-body. A duct is installed between the outer wings and the blended wing-body. The length direction of the duct is parallel to the length direction of the UAV. A fan that rotates around its length direction is installed in the duct. The wing root of the leading edge of the outer wing is flush with the air inlet of the duct, and the wing root of the trailing edge of the outer wing is flush with the air outlet of the duct. The drone has a dual-rotor flight mode and a fixed-wing flight mode. In dual-rotor flight mode, the drone's tilt angle is greater than or equal to 45°, and the vertical component of the fan thrust is greater than the vertical component of the wing lift. In fixed-wing flight mode, the drone's tilt angle is less than or equal to 45°, and the vertical component of the fan thrust is less than the vertical component of the wing lift. The fan is also used to provide thrust when the drone switches flight modes to ensure that the drone's flight altitude remains unchanged when switching flight modes.

2. The ducted unmanned aerial vehicle (UAV) according to claim 1, characterized in that, A flight control board is installed on the blended wing-body. The flight control board is used to adjust the rotation direction of the ailerons to switch the flight mode of the drone based on the ratio of the vertical component of the fan thrust to the vertical component of the wing lift and the horizontal forward speed of the drone.

3. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, In dual-rotor flight mode, the fans in the left and right ducts rotate asynchronously to adjust the roll attitude of the drone, the ailerons on the left and right sides rotate synchronously in the same direction to adjust the pitch attitude of the drone, and the ailerons on the left and right sides rotate synchronously in opposite directions to adjust the yaw attitude of the drone. In fixed-wing flight mode, the fans in the ducts on both sides rotate asynchronously to adjust the yaw attitude of the drone, the ailerons on both sides rotate synchronously in the same direction to adjust the pitch attitude of the drone, and the ailerons on both sides rotate synchronously in opposite directions to adjust the roll attitude of the drone.

4. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, The aileron consists of a first wing section and a second wing section connected along the width of the UAV. The first wing section is directly opposite the trailing edge of the outer wing, and the second wing section is directly opposite the air outlet of the duct. Part of the airflow flowing from the head to the tail of the UAV flows from the air outlet of the duct to the first wing section to form an airflow stabilization zone, thereby reducing the interference area of ​​the airflow flowing from the tail to the head of the UAV on the aileron.

5. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, The wings were made using 3D printing.

6. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, The sweep angle of the outer wing leading edge is 20° to 30°.

7. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, The drone's center of gravity is located at 8% to 12% of the average aerodynamic chord length in front of the drone's focal point.

8. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, Small winglets are provided at the wingtips of the outer wing.

9. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, A triangular support is installed in the middle of the tail of the blended wing-body structure to support the take-off and landing of the drone.

10. The ducted unmanned aerial vehicle (UAV) according to claim 1 or 2, characterized in that, Two servos are also installed in the blended wing-body, each connected to a different aileron, which is used to independently drive the corresponding aileron to rotate relative to the blended wing-body.

Images