Box wing tail-sitter vertical take-off and landing aircraft with attitude fan assisted control and control method

Abstract

The application discloses a box wing rudderless tail stand type vertical take-off and landing aircraft with attitude fan auxiliary control, which comprises a fuselage, upper wings and lower wings arranged on both sides of the fuselage, a main thrust fan group, attitude control fan groups, and the like.The main thrust fan group is distributed in the wing tip area of the upper and lower wings.The attitude control fan groups are distributed in the trailing edge of the upper and lower wings or the extension thereof.The attitude control fan groups provide thrust different from the thrust direction of the main thrust fan group, and the two fan groups cooperatively control the stable operation of the aircraft.The application also provides a control method.The box wing rudderless tail stand type vertical take-off and landing aircraft provided by the application realizes the stable flight of the aircraft by introducing the attitude control fan groups and cooperating with the main thrust fan group, and the aircraft configuration is simple, the manufacturing and maintenance cost is low, and the aircraft is suitable for unmanned aerial vehicle application scenarios under complex working conditions such as freight transportation and inspection.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle technology, and particularly relates to a box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control and a control method thereof. Background Technology

[0002] Vertical takeoff and landing (VTOL) aircraft are widely used in material delivery and emergency inspection scenarios due to their runway-free takeoff and landing advantages. The mainstream products are divided into three categories: multi-rotor, compound wing, and tail-seat type. Tail-seat type relies on the pitch and roll of the whole aircraft to complete the hovering / level flight switching, eliminating the need for tilt wings and tilt power mechanisms, and has outstanding potential for structural lightweighting. However, the existing configurations have always been unable to balance structural simplicity, transitional flight stability, and low-altitude wind resistance.

[0003] Patent document CN115743643A discloses a folding-wing tail-mounted unmanned aerial vehicle (UAV) and its wind disturbance control method. The UAV includes an inner wing section, an outer wing section, a wing folding module, a fuselage folding module, a motor, a propeller, a wind field detection module, and an engine nacelle. Through a variable wing design, the inner wing section and the outer wing section are connected by the wing folding module, and the inner wing section and the fuselage canopy are connected by the fuselage folding module. When there is wind interference, the outer wing section folds towards the inner wing section to reduce the force-bearing area of ​​the folding-wing tail-mounted UAV. When the wind force reaches a certain value, the fuselage folding module is activated, and the fuselage canopy flips upward along the fuselage to reduce the windward area of ​​the inner wing section, thereby reducing the impact of wind disturbance on the UAV.

[0004] Patent document CN121990204A discloses a multi-rotor UAV with a vector composite layout and an energy management and control method, including: a main rotor power system and a thrust vector power system are installed on the wings on the left and right sides of the fuselage; a vertical tail is located on the rear side of the fuselage; the main rotor power systems are installed on the wings in a forward and backward arrangement; and the thrust vector power system is installed on the outer end of the wings. The design adopts a control surface-free design. The main rotor of the main rotor power system directly generates pitch and roll control torques through a differential lift control mechanism. The thrust vector power system provides vector thrust through differential tilt, forming a redundant control of "quadrotor + thrust vector".

[0005] The NASA GL-10 distributed propeller tail-mounted UAV, an existing product, employs a fully movable control surface + wing-mounted distributed propeller layout. Vertical takeoff relies on differential motor attitude control, while level flight relies on aerodynamic control surfaces. Its inherent shortcomings include: 1. The removal of the auxiliary stabilizing tail surface leads to dynamic pitch instability during transitional flight, necessitating the addition of an extra tail fin, increasing weight and drag; 2. At low-altitude hovering, with near-zero airspeed, the aerodynamic control surface's effectiveness approaches zero, making attitude highly dependent on the main propeller thrust margin during hovering and high angle-of-attack transitions, resulting in low crosswind resistance; 3. The numerous components in the control surfaces, shafts, and servo transmission structure lead to a high failure rate in field vibration environments. This model lacks an independent attitude fan at the wing root and a passive recovery aerodynamic layout composed of double-layered box-shaped endplates.

[0006] And the ArduPilot open-source tailless aircraft, which directly adopts the multi-rotor control logic, has no aerodynamic control surfaces and relies solely on the differential speed of the main propulsion motors to achieve attitude adjustment throughout the entire process. Defects: 1. Prominent aerodynamic nonlinearity in the 30°~60° angle-of-attack transition range from hovering to level flight. The main motors must output lift / acceleration thrust and bear the triaxial correction torque, severely squeezing the control thrust margin. Under crosswind disturbances, attitude divergence is highly likely, resulting in low wind resistance. 2. Lack of independent dedicated attitude actuators; deep coupling of power and attitude control functions makes it difficult for the remaining motors to balance load and attitude stability after a single engine failure. 3. Failure to adopt a wing root priority stall + box-type endplate composite passive stabilization structure; relying entirely on real-time power consumption for flight control correction, resulting in high energy consumption. This solution lacks a zoned dedicated wing root attitude control fan and does not integrate a passive aerodynamic recovery structure. Summary of the Invention

[0007] The purpose of this invention is to provide a box-wing, rudderless, tail-seat vertical take-off and landing aircraft and its control method with attitude fan-assisted control. By introducing an attitude control fan group and coordinating it with the main thrust fan group, the aircraft can achieve stable flight. The aircraft has a simple configuration, low manufacturing and maintenance costs, and is suitable for UAV application scenarios in complex working conditions such as cargo transportation and inspection.

[0008] To achieve the first objective of this invention, the following technical solution is provided: a box-wing rudderless tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control, comprising a fuselage, and an upper wing and a lower wing arranged on both sides of the fuselage. The main thrust fan assembly includes main thrust fans distributed in the wingtip areas of the upper and lower wings. Attitude control fan assembly, including attitude control fans distributed on the trailing edges of the upper and lower wings or their extensions; The attitude control fan group provides thrust in a direction different from that of the main thrust fan group, and the two fan groups work together to control the stable operation of the aircraft.

[0009] This invention utilizes an attitude control fan located on the trailing edge of the wing or its extension, which works in conjunction with the main thrust fan to supplement the control torque during hovering, high angle-of-attack transitions, and abnormal single-engine operation conditions. This decouples the "lift + attitude control" function of the main propulsion motor, thereby enhancing the anti-disturbance capability during transitional flight.

[0010] Specifically, the fuselage span is smaller than the distance between the upper and lower wings, thereby reducing airflow obstruction between the wings and enhancing directional stability; Specifically, the span refers to the lateral direction of the wings. That is, when looking down at the aircraft, a straight line is drawn from the centerline of the fuselage to the left and right wingtips respectively. This lateral line is the span (Y-axis).

[0011] Specifically, the fuselage chord direction refers to the longitudinal direction extending from the left and right sides of the wing. That is, when looking down at the aircraft, if you connect the front and rear ends of the fuselage with a straight line, this straight line is the chord direction (X-axis).

[0012] Specifically, the upper wing and the lower wing adopt a differentiated wing surface installation scheme, as detailed below: The upper wing is basically horizontal, meaning the wingtip is basically horizontal relative to its root. The lower wing has an upward dihedral angle, meaning the wingtip is offset upward relative to its root. The ends of the upper and lower wings are connected by endplates, thus forming a roll passive stabilization angle.

[0013] Specifically, the basic level refers to the angle difference between the wingtip and the absolute horizontal plane within the range of -3 degrees to 3 degrees, that is, the angle difference between the wing plane formed by the wingtip and its root and the absolute horizontal plane within the range of -3 degrees to 3 degrees.

[0014] Specifically, each wing features a gradient geometric negative torsion along its span: The wing root section of the fuselage is installed at an angle of 0°, and the torsion angle of the wing tip section relative to the wing root section is in the range of -3° to -8°, so as to achieve a wing root stall angle of attack smaller than that of the wingtip, ensuring that the wing root stalls first at high angles of attack and that the wingtip retains an effective aerodynamic surface.

[0015] Specifically, the lower wing is offset rearward relative to the upper wing along the fuselage chord direction, with the offset amount gradually changing along the span. The offset amount is greatest at the wing root where the lower wing connects to the fuselage to offset the strong interference area of ​​the upper wing's wake. The offset amount at the tip of the lower wing is zero, thereby partially offsetting the strong interference area of ​​the upper wing's wake and matching the reduced aerodynamic interference at the wingtip.

[0016] Specifically, the attitude control fan on the trailing edge of the wing or its extension is located near the wing root region to avoid interference from the slipstream of the main fan at the wingtip, thus preventing any impact on the stability of normal cruise.

[0017] Specifically, the combined force of all the main thrust fans in the main thrust fan group is located in front of the aircraft's center of gravity, thereby providing a natural upward driving force for the aircraft when the main thrust fans work together.

[0018] To achieve the second objective of this invention, the following technical solution is provided: a control method for realizing the controlless flight of a box-wing, controlless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control, comprising the following main states: During takeoff, landing, and hovering, the roll attitude is adjusted by prioritizing differential control of the attitude control fan group; During the transition phase, the pitching moment is supplemented by the differential control of the main thrust fan group and the attitude control fan group, and vertical auxiliary lift is provided to improve the safety and stability of the transition phase. During the level cruise phase, basic control is completed based on the differential speed adjustment of each main thrust fan in the main thrust fan group. The attitude control fan group is in a dormant state. In the event of extreme gusts or failure of the main control, the attitude control fan group provides thrust. When the wing depth stall causes the aircraft to fall naturally, the main thrust fan assembly naturally pulls up because the point of application of the combined force of the main thrust fan assembly is in front of the center of gravity of the aircraft. With the assistance of the attitude control fan assembly, it avoids large rolls or swaying.

[0019] Compared with existing technologies, the beneficial effects of this method are: By using an independent attitude control fan group in conjunction with the main thrust fan group, the necessary control torque is provided in the dangerous range of high angle of attack during the transition of the aircraft, making the overall crosswind resistance significantly better than that of the traditional rudderless tail-seat configuration. Endplates and double-layer differentiated wings form a natural passive aerodynamic restoring torque, and the flight control relies on aerodynamic self-stabilization to reduce correction power consumption and optimize the overall flight performance. The main thrust fan is positioned in front of the aircraft's center of gravity to allow the thrust fan to pull upwards naturally, and with the assistance of the attitude fan, to avoid large-scale rolling or swaying, thus forming a stable attitude similar to that of a multi-rotor. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the box-wing, rudderless, tail-seat vertical takeoff and landing aircraft provided in this embodiment; Figure 2 This is a cross-sectional view of the box-wing, rudderless, tail-seat vertical takeoff and landing aircraft provided in this embodiment; Figure 3 This is a front view of the box-wing, rudderless, tail-seat vertical takeoff and landing aircraft provided in this embodiment; Figure 4 This is a top view of the box-wing, rudderless, tail-seat vertical takeoff and landing aircraft provided in this embodiment; In the diagram, 1. Leading-edge thrust fan; 2. Upper wing; 3. Lower wing; 4. Fuselage; 5. Attitude control fan; 6. Trailing-edge thrust fan; 7. Endplate; 8. Cargo hold; 9. Main thrust fan. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] like Figure 1 and 2 As shown, this embodiment provides a box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control, including a fuselage 4, and an upper wing 2 and a lower wing 3 arranged on both sides of the fuselage 4.

[0023] The main thrust fan assembly includes main thrust fans 9 distributed in the wingtip areas of the upper and lower wings; Attitude control fan assembly, including attitude control fans 5 distributed on the trailing edges of the upper and lower wings or their extensions.

[0024] In this embodiment, an eight-rotor wing scheme is adopted, that is, each wingtip area is provided with a main thrust fan 9, and each main thrust fan 9 is equipped with a leading edge thrust fan 1 and a trailing edge thrust fan 6, thereby providing a stable main driving force for the aircraft during operation. Meanwhile, a safe distance is reserved between the leading-edge thrust fan 1 and the trailing-edge thrust fan 6 to avoid interference with the propeller airflow.

[0025] Furthermore, the above scheme applies to quadcopter or more rotor schemes.

[0026] In this embodiment, the upper wing 2 and the lower wing 3 adopt a carbon fiber composite skin + foam core sandwich structure, with an airfoil of E214 or Clark-Y and a relative thickness of 16%.

[0027] Furthermore, the upper wing 2 and the lower wing 3 adopt differentiated wing surface installation angles. The upper wing 2 is horizontal, and the wingtip of the lower wing 3 is offset upward. The ends of the upper and lower wings on the same side are connected by end plates 7 to form a wing box, which further provides the aircraft with a roll passive stabilization angle.

[0028] In this embodiment, the end plate 7 is a carbon fiber integral molded part with a spanwise thickness using an airfoil profile. The spatial composite angle of the end plate 7 is formed in one step in the mold to avoid secondary bonding. In addition, reinforcing ribs are pre-embedded inside the end plate 7.

[0029] More specifically, the end plate 7 extends outward from the upper and lower sides to form an integrated mounting platform for fixing the main thrust fan 9, while the cavity of the end plate 7 integrates a load-bearing reinforcement structure.

[0030] The fuselage 4 adopts the NACA0015 symmetrical airfoil profile and is formed of carbon fiber composite material.

[0031] The cargo compartment 8 inside the fuselage 4 has a single opening at the back and is equipped with spring-loaded guide rails to fit standard express boxes.

[0032] The cargo hold door 8 is a sliding type with a microswitch. When the door is not fully closed and locked, the flight control logic refuses to initiate the transition procedure. Each wing is equipped with a gradually decreasing geometric negative torsion along its span, meaning that the wing root section installation angle where the wing connects to the fuselage 4 is 0°, and the torsion angle of the wing tip section relative to the wing root section ranges from -3° to -8°, so as to achieve a wing root stall angle of attack smaller than that of the wingtip, ensuring that the wing root stalls first at high angles of attack and that the wingtip retains an effective aerodynamic surface.

[0033] The lower wing 3 is offset rearward relative to the upper wing 2 along the fuselage chord, with the offset gradually changing along the span: approximately 250 mm at the wing root, decreasing to 0 mm at the wingtip, with a smooth transition in the middle area. This gradual offset helps the lower wing to fully escape the strong interference zone of the upper wing's wake at the wing root, while aligning with the upper wing 2 at the tip of the lower wing 3, with the leading edge of the endplate 7 perpendicular to the airflow direction.

[0034] Meanwhile, leading edge fixed serrations are set on the wing, and a certain proportion of half the wingspan area on the inner side of the wing root connected to the fuselage 4 is integrally formed and co-cured through a mold.

[0035] like Figure 3 and Figure 4 As shown, in this embodiment, corresponding attitude control fans 5 are provided at the extensions of the trailing edges of the upper and lower wings. The attitude control fans 5 of the upper wing 2 and the attitude control fans 5 of the lower wing 3 are one-to-one and are both close to the wing root area. Finally, the corresponding attitude control fans 5 on the upper and lower wings provide the aircraft with thrust in a different direction than the thrust provided by the main thrust fan 9.

[0036] More specifically, the attitude control fan assembly may include multiple pairs of attitude control fans 5, which are installed in the vertically aligned openings in the tail region of the wing root area. A reinforcing frame is provided around the opening and is co-cured with the wing root fuselage frame. The corresponding fan motors are connected to the flight controller via quick-connect connectors for easy maintenance and replacement.

[0037] In this embodiment, the main motor of the main thrust fan assembly is mounted on the upper and lower extension platforms of the end plate 7.

[0038] In addition, the aforementioned attitude control fan 5 is normally in a dormant state and is only triggered by the flight control system under specified conditions such as aircraft hovering, level flight transition, crosswind exceeding limits, and single engine failure of the wingtip distributed main thrust fan group; and it needs to be located far away from the slipstream interference area of ​​the wingtip main fan, relying on the differential output of the fan to supplement the pitch and roll control torque.

[0039] This embodiment also provides a control method for realizing the controlless flight of the box-wing tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control as described above. The principle is to achieve the three-axis attitude of the entire aircraft through the coordinated control of the wingtip main fan and the wing root attitude fan in a zoned manner, including the following main states: During takeoff, landing, and hovering, the roll attitude is adjusted by prioritizing differential control of the attitude control fan group; During the transition phase, the pitching moment is supplemented by the differential control of the main thrust fan group and the attitude control fan group, and vertical auxiliary lift is provided to improve the safety and stability of the transition phase. During the level cruise phase, basic control is completed based on the differential speed adjustment of each main thrust fan in the main thrust fan group. The attitude control fan group is in a dormant state. In the event of extreme gusts or failure of the main control, the attitude control fan group provides thrust. When the wing depth stall causes the aircraft to fall naturally, the main thrust fan assembly will naturally pull up because the point of application of the main thrust fan assembly is in front of the aircraft's center of gravity. With the assistance of the attitude control fan assembly, it will avoid large rolls or swaying.

[0040] In addition, during flight control, it is necessary to pre-calculate and deduct the passive restoring torque generated by the fixed structure of the wing and endplate, so as not to consume motor power to counteract the aerodynamic self-stabilizing torque.

[0041] Furthermore, the terms "upper," "lower," "inner," "outer," "front," and "rear" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0042] Of course, the above description is only a specific embodiment of the present invention and does not limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0043] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control, characterized in that, This includes the fuselage, as well as the upper and lower wings located on both sides of the fuselage; The main thrust fan assembly includes main thrust fans distributed in the wingtip areas of the upper and lower wings. Attitude control fan assembly, including attitude control fans distributed on the trailing edges of the upper and lower wings or their extensions; The attitude control fan group provides thrust in a direction different from that of the main thrust fan group, and the two fan groups work together to control the stable operation of the aircraft.

2. The box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control according to claim 1, characterized in that, The span of the fuselage is less than the distance between the upper and lower wings.

3. The box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control according to claim 1, characterized in that, The upper wing and the lower wing adopt a differentiated wing surface installation scheme, as detailed below: The upper wing is basically horizontal, that is, the wingtip is basically horizontal relative to its root height, and the lower wing is provided with an upward dihedral angle, that is, the wingtip is offset upward relative to its root height. The ends of the upper and lower wings are connected by end plates.

4. The box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control according to claim 1, characterized in that, Each wing features a gradient geometric negative torsion along its span: The wing root section of the wing connecting to the fuselage has an installation angle of 0°, and the torsion angle of the wing tip section relative to the wing root section ranges from -3° to -8°.

5. The box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control according to claim 1, characterized in that, The lower wing is offset rearward relative to the upper wing along the fuselage chord, with the offset amount gradually changing along the span. The offset amount is greatest at the wing root where the lower wing connects to the fuselage to avoid the strong interference area of ​​the upper wing's wake, and the offset amount at the tip of the lower wing is 0.

6. The box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control according to claim 1, characterized in that, The attitude control fan on the trailing edge of the wing or its extension is located near the wing root region.

7. The box-wing, rudderless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control according to claim 1, characterized in that, The combined force of all the main thrust fans in the main thrust fan assembly is located in front of the aircraft's center of gravity.

8. A control method, characterized in that, For achieving controlless flight of a box-wing, controlless, tail-seat vertical takeoff and landing aircraft with attitude fan-assisted control as described in any one of claims 1 to 7, the following main states are included: During takeoff, landing, and hovering, the roll attitude is adjusted by prioritizing differential control of the attitude control fan group; During the transition phase, the pitching moment is supplemented by the differential control of the main thrust fan group and the attitude control fan group, and vertical auxiliary lift is provided to improve the safety and stability of the transition phase. During the level cruise phase, basic control is completed based on the differential speed adjustment of each main thrust fan in the main thrust fan group. The attitude control fan group is in a dormant state. In the event of extreme gusts or failure of the main control, the attitude control fan group provides thrust. When the wing depth stall causes the aircraft to fall naturally, the main thrust fan assembly naturally pulls up because the point of application of the combined force of the main thrust fan assembly is in front of the center of gravity of the aircraft. With the assistance of the attitude control fan assembly, it avoids large rolls or swaying.

Images