Small tandem biplane unmanned aerial vehicle with wingtip duct drag reduction and design method thereof
By integrating ducted propulsion units into the wingtips of small tandem biplane UAVs, the problems of high wingtip induced drag, low propulsion efficiency, and insufficient safety have been solved, achieving synergistic effects of efficient propulsion and drag reduction, and improving endurance and flight safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN INSTITUTE OF INFORMATION TECHNOLOGY
- Filing Date
- 2026-03-23
- Publication Date
- 2026-07-03
AI Technical Summary
Existing small tandem biplane UAVs suffer from problems such as high wingtip induced drag, lack of coordination between propulsion and drag reduction, poor structural adaptability, insufficient flight safety, and a lack of targeted design methods, resulting in short endurance, high energy consumption, susceptibility to obstacle collisions, and mismatched overall performance.
The ducted propulsion unit is integrated into the wingtip, including the duct body, rotatable ducted blades and motor. It is connected to the main wing and horizontal tail through a streamlined connecting base. The inner diameter of the duct body is matched with the blade diameter, the air intake lip is adapted to the airflow angle, and the fairing protects the blades. The parameters of the ducted propulsion unit are optimized by combining CFD simulation to achieve modular design.
It significantly reduces induced drag by more than 20%, improves propulsion efficiency by 25%, adapts to the characteristics of small UAVs, enhances low-altitude safety, ensures that the overall performance is precisely matched with mission requirements, and reduces the increase in overall weight.
Smart Images
Figure CN122324312A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of unmanned aerial vehicle (UAV) technology, and in particular to a small tandem biplane UAV configuration and design method with wingtip duct drag reduction. Background Technology
[0002] Small tandem biplane drones are widely used in urban inspection, environmental monitoring, and small-scale material delivery due to their high lift margin, good low-speed flight stability, and flexible payload arrangement. Current designs for small tandem biplane drones typically employ simple, straight wing structures, with open wingtips or only small fixed endplates. Propulsion systems often use a single propeller at the tail of the fuselage or a micro-motor mounted in the middle of the wing, without integration with the wingtip structure.
[0003] Some existing technologies attempt to add exposed propellers to the wingtips of small tandem biplane drones, hoping to disrupt wingtip vortices through propeller rotation. However, such solutions have simple propeller-to-wingtip connections, resulting in an uneven aerodynamic transition, and lack parameter matching for the low-load, low-power characteristics of small drones. Specifically, existing technologies for small tandem biplane drones suffer from the following drawbacks: 1. High proportion of induced drag at the wingtip: Small tandem biplane UAVs have short wingspans and relatively concentrated vortex intensity at the wingtip. Traditional fixed endplates can only slightly weaken the vortex, and the proportion of induced drag in the total drag can reach more than 40%, resulting in short endurance and high energy consumption, making it difficult to meet the requirements of long-endurance missions.
[0004] 2. Lack of coordination between propulsion and drag reduction: The propulsion system is arranged independently from the wingtip structure. The exposed propeller is susceptible to interference from wingtip vortices, resulting in large thrust fluctuations and reduced propulsion efficiency. At the same time, the aerodynamic drag of the propeller itself further increases the energy consumption of the whole aircraft, which is not compatible with the low power requirements of small UAVs.
[0005] 3. Poor structural adaptability: The wingtip components are mostly integrated designs, making it impossible to replace different specifications of propulsion / drag reduction modules according to mission payload, flight speed and other requirements. In addition, the wingtip space of small UAVs is limited, and the maintenance and disassembly of traditional structures are difficult.
[0006] 4. Insufficient flight safety: Small drones mostly operate in low-altitude urban areas, and exposed propellers are prone to collisions with obstacles, which can damage the drone and pose safety hazards. At the same time, exposed propellers generate significant aerodynamic noise, which can disturb the urban environment.
[0007] 5. Lack of targeted design methodology: Existing designs do not take into account the characteristics of small UAVs, such as "low weight, small size, and low power", and have not established a method for matching the miniaturized parameters of the wingtip flow field and the ducted propeller, resulting in redundancy or inadequacy in the overall performance. Summary of the Invention
[0008] To overcome the shortcomings of the prior art, this invention provides a small tandem biplane unmanned aerial vehicle (UAV) structure with wingtip duct drag reduction and its design method. It aims to solve the problems of wingtip drag reduction, propulsion efficiency and structural adaptability of small tandem biplane UAVs in the prior art, achieve synergistic effect of drag reduction and propulsion, and improve its aerodynamic efficiency, endurance and flight safety.
[0009] This invention provides a small tandem biplane unmanned aerial vehicle (UAV) configuration with wingtip duct drag reduction, comprising: body; The main wing is fixedly connected to the middle or front part of the fuselage; A horizontal tail fin is fixedly connected to the rear of the fuselage and arranged in tandem with the main wing. A ducted propulsion unit is disposed at the wingtip of the main wing and / or the horizontal tail wing. The ducted propulsion unit includes a duct body, ducted blades rotatably disposed within the duct body, and a motor for driving the ducted blades to rotate. The axial direction of the duct body extends in the same direction as the average incoming flow direction at the corresponding wingtip.
[0010] As a further improvement of the present invention, a connecting base is provided at the wingtip of the main wing and / or the horizontal tail wing, and the duct body is connected to the wingtip of the main wing and / or the horizontal tail wing through the connecting base, and the surface of the connecting base has a streamlined arc transition structure.
[0011] As a further improvement of the present invention, the main wing and horizontal wing are made of lightweight, high-performance materials.
[0012] As a further improvement of the present invention, the lightweight high-performance material is a carbon fiber plate.
[0013] As a further improvement of the present invention, the ducted blade includes three blades.
[0014] As a further improvement of the present invention, the motor is connected to the duct body, and the rotor of the motor is connected to the duct blades.
[0015] As a further improvement of the present invention, the inner diameter of the duct body is matched with the diameter of the blade, and the outer shell of the duct body conformally transitions to the wingtip of the main wing and / or the horizontal tail.
[0016] As a further improvement of the present invention, the duct body is provided with an air inlet lip, the curvature of which is adapted to the airflow angle of the main wing and / or the horizontal tail wing.
[0017] As a further improvement of the present invention, the duct body is provided with an integrated interface.
[0018] To achieve the above objectives, the present invention also proposes a design method for a small tandem biplane unmanned aerial vehicle configuration with drag reduction via wingtip ducts as described above, the method comprising the following steps: Step S10: Determine the basic parameters of the small UAV and calculate the wingtip vortex intensity and induced drag under the traditional configuration through CFD simulation. The basic parameters include takeoff weight, endurance time, cruise speed, and wingspan of the main wing and horizontal tail. Step S20: Perform wingtip flow field simulation on the tandem biplane body under cruise conditions to obtain data on wingtip vortex core position, incoming flow velocity and airflow angle. Step S30: Based on the wingtip flow field simulation data obtained in step S20, determine the parameters of the ducted propulsion unit. The parameters of the ducted propulsion unit include the duct body dimensions, blade dimensions, and motor parameters. Step S40: Perform separate aerodynamic simulation and optimization on the ducted propulsion unit to ensure that it meets the preset wingtip vortex suppression rate and propulsion efficiency targets. Step S50: Install the optimized ducted propulsion unit onto the wingtip of the main wing and / or horizontal tail of the tandem biplane main body model and perform aerodynamic joint simulation of the whole aircraft. Perform aerodynamic joint simulation of the whole aircraft to verify whether the induced drag reduction effect and thrust meet the cruise requirements, and fine-tune the installation angle of the ducted propulsion unit accordingly. Step S60: Based on the wingtip flow field simulation data obtained in S20 and the assembly relationship determined in step S50, design a modular interface for detachable connection between the ducted propulsion unit and the wingtip of the main wing and / or horizontal tail. Step S70: Perform micro-structural strength simulation and verification on the modular interface and the duct body, and control the increase in overall weight caused by adding the duct propulsion unit.
[0019] The beneficial effects of the small tandem biplane unmanned aerial vehicle (UAV) configuration and design method with wingtip duct drag reduction of the present invention are: 1. Significantly reduce induced drag: By actively suppressing eddy currents through the ducted propulsion unit, induced drag can be reduced by more than 20%, and cruise energy consumption can be reduced by more than 20%.
[0020] 2. Improve propulsion efficiency: The ducted propulsion unit rectifies the propeller's propulsion efficiency by 25%, and the low-power motor is compatible with the battery capacity of small UAVs, avoiding power redundancy.
[0021] 3. Adaptable to small UAV characteristics: The modular ducted propulsion unit is weight and size matched to the wingtip, without adding extra aerodynamic drag; the quick-assembly and disassembly design allows for the replacement of different power modules according to the mission.
[0022] 4. Improved low-altitude safety: The ducted propulsion unit protects the blades with a fairing, which can avoid collisions with low-altitude obstacles in the city and is suitable for urban operating environments.
[0023] 5. Highly targeted design: Parameter matching is performed based on the low weight and low power requirements of small drones to ensure that the overall performance is accurately adapted to the mission requirements and avoid structural redundancy. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the overall structure of a preferred embodiment of the small tandem biplane unmanned vehicle with wingtip duct drag reduction of the present invention; Figure 2 This is a schematic diagram of the aerodynamic principle of a preferred embodiment of the small tandem biplane unmanned structure with wingtip duct drag reduction of the present invention; Figure 3 This is a schematic diagram of the ducted propulsion unit; Figure 4 This is a schematic diagram showing the connection between the ducted propulsion unit and the main wing and / or horizontal wing; Figure 5 This is a schematic diagram illustrating the design process of the small tandem biplane unmanned structure with drag reduction via wingtip ducts according to the present invention.
[0025] Explanation of icon numbers: fuselage 10; main wing 20; Horizontal stabilizer 30; Ducted propulsion unit 40: duct body 401; blade 402; motor 403; fairing 404; Connecting shaft 50. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0027] This invention proposes a small tandem biplane unmanned aerial vehicle (UAV) configuration with wingtip duct drag reduction, such as... Figures 1 to 4 As shown, a preferred embodiment of the small tandem biplane unmanned aircraft configuration with wingtip duct drag reduction of the present invention includes a fuselage 10, a main wing 20, a horizontal tail 30, and a ducted propulsion unit 40.
[0028] The main wing 20 is fixedly connected to the middle or front of the fuselage 10, and the horizontal tail 30 is fixedly connected to the rear of the fuselage 10, arranged in a tandem with the main wing 20. The ducted propulsion unit 40 is disposed at the wingtip of the main wing 20 and / or the horizontal tail 30. The ducted propulsion unit 40 includes a duct body 401, a ducted blade 402 rotatably disposed within the duct body 401, and a motor 403 for driving the ducted blade 402 to rotate; wherein the extension direction of the axis of the duct body 401 is consistent with the average incoming flow direction of the corresponding wingtip.
[0029] In this embodiment, the fuselage 10, main wing 20, and horizontal tail 30 with a low-profile design are securely assembled into a single unit using lightweight connectors. Both the main wing 20 and the horizontal tail 30 are made of lightweight, high-performance materials, such as high-strength, lightweight carbon fiber sheets, ensuring both structural load-bearing capacity and effective control of the overall weight, thus meeting the low-payload requirements of small unmanned aerial vehicles (UAVs).
[0030] A connecting base (not shown in the figure) is provided at the wingtip of the main wing 20 and / or the horizontal tail 30. The duct body 401 is connected to the wingtip of the main wing 20 and / or the horizontal tail 30 through the connecting base. The surface of the connecting base has a streamlined arc transition structure.
[0031] In this embodiment, standardized miniature connecting bases are pre-installed at the wingtips of the main wing 20 and / or the horizontal tail 30. The dimensions of these connecting bases are precisely matched to the interface of the subsequently installed ducted propulsion unit 40. The outer surface of the connecting base adopts a streamlined arc transition treatment, which allows a smooth aerodynamic connection surface to be formed between the connecting base and the fuselage 10 and the ducted propulsion unit 40. This avoids local airflow separation problems caused by structural abrupt changes, thereby ensuring the aerodynamic smoothness of the entire aircraft during flight and reducing unnecessary additional drag.
[0032] It should be noted that, in other embodiments, the duct body 401 may also be connected to the main wing 20 and / or the horizontal tail wing 30 via the connecting shaft 50.
[0033] Furthermore, in this embodiment, the ducted propeller 402 includes three blades 402, mounted on the rotor of the motor 403. Of course, in other embodiments, the number of blades 402 can be set according to actual needs. The blades 402 are low-speed, high-efficiency blades, with a rotational speed suitable for the propulsion power of a small UAV. The motor 403 housing uses a low-power-to-weight ratio brushless micromotor 403.
[0034] The motor 403 is connected to the duct body 401, and the rotor of the motor 403 is connected to the duct blade 402.
[0035] The inner diameter of the duct body 401 matches the diameter of the blade 402, and the outer shell of the duct body 401 conformally transitions to the wingtip of the main wing 20 and / or the horizontal tail 30. For example... Figure 2 As shown, when the airflow flows from the surface of the fuselage 10 to the ducted propulsion unit 40, the smooth transition can eliminate interference drag, and the shell of the duct body 401 can suppress wingtip vortices, improve the lift-to-drag ratio, and thus ensure aerodynamic integration.
[0036] Furthermore, in this embodiment, the duct body 401 is provided with an air inlet lip, the curvature of which is adapted to the airflow angle of the main wing 20 and / or the horizontal tail wing 30.
[0037] This embodiment, by providing the air inlet lip on the duct body 401, ensures that the airflow enters the duct smoothly, reduces flow separation and energy loss, thereby improving the working efficiency of the blades 402 inside the duct body 401 and the overall drag reduction effect.
[0038] Furthermore, in this embodiment, an integrated interface is provided outside the duct body 401, which can be used to constrain each signal line.
[0039] As one implementation scheme, a fairing 404 is provided at the front end of the duct body 401 in this embodiment. This can improve the safety of low-altitude operations in urban areas.
[0040] The beneficial effects of the small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction of the present invention are: 1. Significantly reduce induced drag: By actively suppressing eddy currents through the ducted propulsion unit, induced drag can be reduced by more than 20%, and cruise energy consumption can be reduced by more than 20%.
[0041] 2. Improve propulsion efficiency: The ducted propulsion unit rectifies the propeller's propulsion efficiency by 25%, and the low-power motor is compatible with the battery capacity of small UAVs, avoiding power redundancy.
[0042] 3. Adaptable to small UAV characteristics: The modular ducted propulsion unit is weight and size matched to the wingtip, without adding extra aerodynamic drag; the quick-assembly and disassembly design allows for the replacement of different power modules according to the mission.
[0043] 4. Improved low-altitude safety: The ducted propulsion unit protects the blades with a fairing, which can avoid collisions with low-altitude obstacles in the city and is suitable for urban operating environments.
[0044] 5. Highly targeted design: Parameter matching is performed based on the low weight and low power requirements of small drones to ensure that the overall performance is accurately adapted to the mission requirements and avoid structural redundancy.
[0045] To achieve the above objectives, the present invention also proposes a design method for a small tandem biplane unmanned aerial vehicle configuration with drag reduction via wingtip ducts as described above, such as... Figure 5 As shown, a preferred embodiment of the design method for a small tandem biplane unmanned aerial vehicle (UAV) with wingtip duct drag reduction according to the present invention includes the following steps: Step S10: Determine the basic parameters of the small UAV and calculate the wingtip vortex intensity and induced drag under the traditional configuration through CFD simulation. The basic parameters include takeoff weight, endurance, cruise speed, and wingspan of the main wing and horizontal tail.
[0046] In this embodiment, the basic parameters of the small UAV can be set according to actual needs as follows: takeoff weight ≤ 5kg, flight time ≥ 30min, cruising speed ≤ 15m / s, and wingspan of the main wing and horizontal tail ≤ 2m.
[0047] Step S20: Perform wingtip flow field simulation on the tandem biplane body under cruise conditions to obtain data on the wingtip vortex core position, incoming flow velocity (≤15m / s), and airflow angle.
[0048] Step S30: Based on the wingtip flow field simulation data obtained in step S20, determine the parameters of the ducted propulsion unit. The parameters of the ducted propulsion unit include the duct body dimensions, blade dimensions, and motor parameters.
[0049] In this embodiment, the inner diameter of the duct body is ≤100mm, the length is ≤150mm, and the curvature of the duct inlet lip is adapted to the wingtip inflow angle; the diameter of the blade is ≤90mm, the number of blades is 2-3, and the pitch is matched with the cruise speed; the motor power is ≤50W, and the blade speed is adapted based on the KV value.
[0050] Step S40: Perform separate aerodynamic simulation and optimization on the ducted propulsion unit to ensure that it meets the preset wingtip vortex suppression rate and propulsion efficiency targets.
[0051] In this embodiment, the wingtip vortex suppression rate is 50%, while the propeller propulsion efficiency is ≥75%.
[0052] Step S50: Install the optimized ducted propulsion unit onto the wingtip of the main wing and / or horizontal tail of the tandem biplane main body model for whole-aircraft aerodynamic joint simulation. Perform whole-aircraft aerodynamic joint simulation to verify whether the induced drag reduction effect and thrust meet the cruise requirements. Based on this, fine-tune the installation angle of the ducted propulsion unit so that the installation angle is consistent with the airflow angle at the wingtip, ensuring that the induced drag of the whole aircraft is reduced by ≥60% and the thrust meets the cruise requirements.
[0053] Step S60: Based on the wingtip flow field simulation data obtained in S20 and the assembly relationship determined in step S50, design a modular interface for detachable connection between the ducted propulsion unit and the wingtip of the main wing and / or horizontal tail.
[0054] In this embodiment, the inner diameter of the modular interface is ≤100 mm and the length is ≤150 mm, which enables "one-click assembly and disassembly" of the ducted propulsion unit and the wingtip.
[0055] Step S70: Perform micro-structural strength simulation and verification on the modular interface, connecting base and duct body, and control the increase in overall weight caused by the addition of the duct propulsion unit to ensure no deformation under 1.5 times cruise thrust, while the increase in overall weight is ≤0.3kg.
[0056] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.
Claims
1. A small tandem biplane unmanned aerial vehicle (UAV) configuration with wingtip duct drag reduction, characterized in that, include: body; The main wing is fixedly connected to the middle or front part of the fuselage; A horizontal tail fin is fixedly connected to the rear of the fuselage and arranged in tandem with the main wing. A ducted propulsion unit is disposed at the wingtip of the main wing and / or the horizontal tail wing. The ducted propulsion unit includes a duct body, ducted blades rotatably disposed within the duct body, and a motor for driving the ducted blades to rotate. The axial direction of the duct body extends in the same direction as the average incoming flow direction at the corresponding wingtip.
2. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 1, characterized in that, A connecting base is provided at the wingtip of the main wing and / or the horizontal tail wing, and the duct body is connected to the wingtip of the main wing and / or the horizontal tail wing through the connecting base. The surface of the connecting base has a streamlined arc transition structure.
3. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 2, characterized in that, The main wing and horizontal wings are made of lightweight, high-performance materials.
4. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 3, characterized in that, The lightweight, high-performance material is carbon fiber plate.
5. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 1, characterized in that, The duct blades consist of three blades.
6. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 5, characterized in that, The motor is connected to the duct body, and the rotor of the motor is connected to the duct blades.
7. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 6, characterized in that, The inner diameter of the duct body matches the diameter of the blade, and the outer shell of the duct body conformally transitions to the wingtip of the main wing and / or horizontal tail.
8. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 1, characterized in that, The duct body is provided with an air inlet lip, the curvature of which is adapted to the airflow angle of the main wing and / or horizontal tail fin.
9. The small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction according to claim 1, characterized in that, The duct body is provided with an integrated interface.
10. A design method for a small tandem biplane unmanned aerial vehicle configuration with wingtip duct drag reduction as described in any one of claims 1 to 9, characterized in that, The method includes the following steps: Step S10: Determine the basic parameters of the small UAV and calculate the wingtip vortex intensity and induced drag under the traditional configuration through CFD simulation. The basic parameters include takeoff weight, endurance time, cruise speed, and wingspan of the main wing and horizontal tail. Step S20: Perform wingtip flow field simulation on the tandem biplane body under cruise conditions to obtain data on wingtip vortex core position, incoming flow velocity and airflow angle. Step S30: Based on the wingtip flow field simulation data obtained in step S20, determine the parameters of the ducted propulsion unit. The parameters of the ducted propulsion unit include the duct body dimensions, blade dimensions, and motor parameters. Step S40: Perform separate aerodynamic simulation and optimization on the ducted propulsion unit to ensure that it meets the preset wingtip vortex suppression rate and propulsion efficiency targets. Step S50: Install the optimized ducted propulsion unit onto the wingtip of the main wing and / or horizontal tail of the tandem biplane main body model and perform aerodynamic joint simulation of the whole aircraft. Perform aerodynamic joint simulation of the whole aircraft to verify whether the induced drag reduction effect and thrust meet the cruise requirements, and fine-tune the installation angle of the ducted propulsion unit accordingly. Step S60: Based on the wingtip flow field simulation data obtained in S20 and the assembly relationship determined in step S50, design a modular interface for detachable connection between the ducted propulsion unit and the wingtip of the main wing and / or horizontal tail. Step S70: Perform micro-structural strength simulation and verification on the modular interface and the duct body, and control the increase in overall weight caused by adding the duct propulsion unit.