A tailstock-type three-ducted vertical takeoff and landing aircraft and its control method

Abstract

The present invention discloses a tailstock-type three-ducted vertical takeoff and landing aircraft and its control method, which includes an aircraft fuselage. The front section of the aircraft fuselage is an airborne equipment cabin, the middle section is a payload cabin, and the rear section is a power cabin. A pair of foldable wing components are symmetrically arranged on both sides of the payload cabin. Each foldable wing component includes a first straight wing fixed to the outer wall of the payload cabin, a second straight wing foldably fixed to the first straight wing, and an aileron arranged on the second straight wing. Three power components are evenly fixed along the circumferential direction of the outer wall of the power cabin. Each power component includes a duct fixed to the outer wall of the power cabin, a motor fixed in the duct, and a propeller. A plurality of tail wing components are evenly fixed at the tail end of the power cabin. A flight controller for controlling the foldable wing components, power components, and tail wing components is provided in the airborne equipment cabin. The present invention can not only take off and land vertically but also cruise in a fixed-wing mode, and can efficiently perform tasks in scenarios with limited environments.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft, and particularly relates to a tail-sitter three-ducted vertical takeoff and landing aircraft and a control method thereof. Background Art

[0002] In recent years, with the wide application of unmanned aerial vehicles (UAVs) in various fields, their usage environments and operation tasks have become increasingly complex. The convenience and safety of the takeoff and landing scheme are important factors determining the continuous operation ability of UAVs in harsh environments such as the sea surface and mountainous areas. Therefore, the functional characteristics of vertical takeoff and landing are of great significance for the application expansion of UAVs. Multirotor UAVs and fixed-wing UAVs have their own advantages in vertical takeoff and landing and high-speed cruising respectively. How to fully combine these two major advantageous features will be the key issue to solve the large-scale application of UAVs in restricted environments.

[0003] Vertical takeoff and landing aircraft are divided into three categories: tilt-rotor type, compound type, and tail-sitter type. For example, a Chinese patent document with the publication number CN108482668A discloses a tilt-type vertical takeoff and landing aircraft, and a Chinese patent document with the publication number CN105923154A discloses a tandem dual-rotor fixed-wing compound vertical takeoff and landing aircraft. The tilt-type vertical takeoff and landing aircraft is complex to control during the tilting process, with high technical difficulty and risk; the compound vertical takeoff and landing aircraft includes two sets of power systems for vertical takeoff and landing and horizontal flight propulsion, resulting in a low payload and large flight resistance caused by the exposed propellers in fixed-wing flight; while the tail-sitter vertical takeoff and landing aircraft is in between, ensuring that the vertical takeoff and landing aircraft has better payload capacity and reducing the control complexity. It is the key development form of the external shape layout and control of vertical takeoff and landing aircraft at present.

[0004] In existing research, models such as the elastic rotor tail-sitter UAV of Aerovel Company, the TERN "Tern" tail-sitter UAV proposed by Northrop Grumman Corporation in the United States, and the VD-200 tail-sitter UAV exhibited by Chengdu Aircraft Industry (Group) Co., Ltd. in China all adopt open propellers and an integrated or longer wingspan wing structure, which can achieve better horizontal flight performance, but do not consider the problems of transitional state stability and vertical takeoff and landing flight resistance much, and due to the exposure of their power systems, the overall efficiency and safety of the aircraft are reduced.

[0005] Therefore, it is an urgent problem for those skilled in the art to provide an aircraft that can not only take off and land vertically, but also cruise at high speed and has higher efficiency and safety. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a tail-sitter three-ducted vertical takeoff and landing aircraft, which can not only take off and land vertically but also cruise in a fixed-wing mode, can efficiently perform tasks in scenarios with limited environments, and its unique design greatly improves the overall efficiency and safety.

[0007] A tail-seat type three-ducted vertical takeoff and landing aircraft, including an aircraft fuselage. The front section of the aircraft fuselage is an airborne equipment compartment, the middle section is a payload compartment, and the rear section is a power compartment.

[0008] On both sides of the payload compartment, a pair of foldable wing components are symmetrically arranged. Each foldable wing component includes a first straight wing fixed to the outer wall of the payload compartment, a second straight wing foldably fixed to the first straight wing, and ailerons arranged on the second straight wing.

[0009] On the outer wall of the power compartment, three power components are uniformly fixed along the circumferential direction. Each power component includes a duct fixed to the outer wall of the power compartment, a motor fixed inside the duct, and a propeller connected to the output end of the motor.

[0010] At the tail end of the power compartment, a plurality of tail wing components are uniformly fixed. Each tail wing component includes a tail wing fixed to the tail end of the power compartment, a tail wing rudder arranged on the tail wing, and a landing gear arranged at the end of the tail wing.

[0011] Inside the airborne equipment compartment, a flight controller for controlling the foldable wing components, power components, and tail wing components and other necessary airborne equipment are provided, which are used to control the flight process of the aircraft.

[0012] The tail-seat type three-ducted vertical takeoff and landing aircraft provided by the present invention can not only take off and land vertically but also cruise in a fixed-wing mode, and the overall efficiency and safety are greatly improved, solving the technical problems of the complex control system, large flight resistance, and weak load capacity of the existing vertical takeoff and landing aircraft.

[0013] Preferably, a back hatch and a belly hatch are provided on the payload compartment. The belly hatch can be used for dropping military supplies, and the back hatch can be used for logistics transportation.

[0014] The power compartment is mainly used to place large-capacity lithium batteries, generators, fuel, etc. The fuel is provided to the generator for power generation, and the lithium battery is continuously charged through the engine power generation. The lithium battery is used to supply power to the motor.

[0015] Furthermore, the airfoils of the first straight wing and the second straight wing are both NACA6412, and the two are connected by a hinge; the second straight wing is in a folded state during vertical flight of the aircraft and in an unfolded state during horizontal flight; among them, the maximum folding angle of the second straight wing is 120 degrees.

[0016] Furthermore, the surfaces of the first straight wing and the second straight wing are covered with solar photovoltaic thin films, and the electrical energy output of the solar photovoltaic thin films is connected to the lithium battery arranged inside the power compartment. The wings covered with solar photovoltaic thin films have excellent performances such as ultra-long endurance, silent flight, and low emissions.

[0017] Further, among the three power components, one is fixed directly below the power cabin, and the other two are symmetrically fixed above the power cabin. The fixed angular interval between the three power components is 120°. The total maximum available pulling force provided by the power components is not less than the takeoff weight of the UAV.

[0018] Further, two motors facing each other along the axial direction are provided inside the ducted fan. Each motor is connected to a corresponding propeller. The propeller is a two-blade propeller that meets the pulling force requirements, with a model number of 2788, and the installation method is coaxial counter-rotation.

[0019] Further, an annular cut groove for suppressing the tip vortex of the propeller is provided on the inner wall of the ducted fan. The ratio of the depth of the cut groove to the length of the part of the blade immersed is 2:1. A streamlined airfoil structure for lift augmentation is provided on the outer wall of the ducted fan.

[0020] The fuselage of the aircraft is designed to be streamlined with a left-right symmetric cross-section. The tail wing component and the power component are axially coincident to maximize the control effect of the control surface. The ailerons and tail wing rudders can be deflected under the drive of the servo motors and transmission mechanisms.

[0021] The present invention also provides a control method for a tail-sitter three-ducted fan vertical takeoff and landing aircraft. The mission execution process of the aircraft is divided into seven stages: ground preparation, vertical takeoff, vertical-to-horizontal mode switching, mission cruise, horizontal-to-vertical mode switching, vertical landing, and ground recovery. The control method for each stage is as follows:

[0022] Ground preparation: The aircraft is rapidly deployed through modular assembly. After the deployment of the aircraft is completed, relevant system tests are carried out and it enters the ready-to-fly state. At this time, the fuselage should be perpendicular to the ground, and the foldable wing components are in the folded state;

[0023] Vertical takeoff: Start the motors and keep them at idle speed. After confirming normal operation, adjust the motor speeds of each power component. After the thrust is greater than the gravity, the aircraft leaves the ground and starts to accelerate upward; Before the flight speed reaches the specified mode switching speed, the foldable wing components always remain in the folded state, and the position and attitude of the aircraft are regulated by adjusting the motor speeds of each power component; After the aircraft enters the target altitude range and the flight speed is greater than the specified mode switching speed, the foldable wing components are unfolded, and the aircraft enters the mode switching stage;

[0024] Vertical-to-horizontal mode switching: Generate a pitching moment on the fuselage by adjusting the motor speeds of each power component and the tail wing control surface, and adjust the pitch angle from 90° during vertical ascent to the trim value in the cruise state. During this process, the flight altitude of the aircraft gradually stabilizes until finally a cruise flight state is established;

[0025] Mission cruise: The thrust of each power component remains equal throughout this stage. The attitude control of the aircraft is determined only by the control amounts of each rudder surface. The specific control method is to achieve the yaw and pitch movements of the aircraft through the tail rudder surface, and the roll movement of the aircraft through the ailerons;

[0026] Horizontal to vertical mode switching: By adjusting the motor speeds of each power component and the tail rudder surface, a pitch moment is generated on the airframe, and the pitch angle is adjusted from the trim value in the cruise state to 90° for vertical landing. During this process, the flight altitude of the aircraft gradually increases until finally a hovering flight state is established;

[0027] Vertical landing: After completing the horizontal to vertical mode switching, fold the foldable wing components of the aircraft, and adjust the position and attitude of the aircraft by adjusting the motor speeds of each power component to gradually decrease the altitude of the aircraft;

[0028] Ground recovery: When the aircraft completes the mission and lands on the ground, perform relevant maintenance and disassembly for transportation.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention uses a tail-sitter vertical takeoff and landing method for takeoff and landing, and adopts a fixed-wing mode for cruise flight during the level flight stage. Its vertical takeoff power and level flight power are combined into one, with higher overall efficiency; since the aircraft uses a ducted device, its propeller is installed inside the duct, which is safer and has lower noise; and because the duct can reduce the induced drag at the tip of the blade, compared with a propeller with the same disk diameter without a duct structure, it has higher thrust and efficiency, so the propeller size can be appropriately reduced and sufficient power can be provided.

[0031] 2. The foldable wings designed in the present invention can reduce the windward area of the aircraft during takeoff and landing, improving the anti-interference ability and flight stability during the working process.

[0032] 3. The present invention adopts an extended-range hybrid oil-electric propulsion system. The propeller is driven by an electric motor, and the engine continuously generates electricity to supplement the electric energy to increase the endurance. Description of the drawings

[0033] Figure 1 It is a schematic diagram of the overall structure of a tail-sitter three-ducted vertical takeoff and landing aircraft of the present invention;

[0034] Figure 2 It is a schematic diagram of the disassembly and assembly of each component in the present invention;

[0035] Figure 3 It is a schematic diagram of the aircraft structure during the horizontal flight stage;

[0036] Figure 4Schematic diagram of the aircraft structure during the vertical takeoff and landing phase;

[0037] Figure 5 Schematic diagram of the structure of the power component;

[0038] Figure 6 Schematic diagram of the mission execution process of the aircraft of the present invention. Specific embodiments

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention and do not impose any limitations on it.

[0040] As Figure 1 and Figure 2 shown, a tail-sitter three-ducted vertical takeoff and landing aircraft includes an aircraft fuselage 1. The front section of the aircraft fuselage 1 is an on-board equipment compartment 101, the middle section is a payload compartment 102, and the rear section is a power compartment 103.

[0041] A back hatch 1021 and a belly hatch 1022 are provided on the payload compartment 102. The belly hatch 1022 can be used for dropping military supplies, and the back hatch 1021 can be used for logistics transportation.

[0042] A pair of foldable wing components 2 are symmetrically provided on both sides of the payload compartment 102. Each foldable wing component 2 includes a first straight wing 201 fixed to the outer wall of the payload compartment 102, a second straight wing 202 foldably fixed to the first straight wing 201, and an aileron 203 provided on the second straight wing 202.

[0043] Three power components 3 are uniformly fixed along the circumferential direction of the outer wall of the power compartment 103. Each power component 3 includes a duct 301 fixed to the outer wall of the power compartment 103, a motor 303 fixed in the duct 301, and a propeller 302 connected to the output end of the motor 303.

[0044] A plurality of tail wing components 4 are uniformly fixed at the tail end of the power compartment 103. Each tail wing component 4 includes a tail wing 401 fixed to the tail end of the power compartment 103, a tail fin rudder 402 provided on the tail wing 401, and a landing gear 403 provided at the end of the tail wing 401.

[0045] A flight controller for controlling the foldable wing component 2, the power component 3, and the tail wing component 4 and other necessary on-board equipment are provided in the on-board equipment compartment 101 for controlling the flight process of the aircraft.

[0046] In the embodiment of the present invention, the airfoils of the first straight wing 201 and the second straight wing 202 are both NACA6412, and the two are connected by a hinge; the second straight wing 202 is in an unfolded state when the aircraft is flying horizontally, as Figure 3As shown, the wing is 5 meters long after deployment and has an average chord length of 0.3 meters. The second straight wing 202 is in a folded state during the vertical flight of the aircraft, as Figure 4 shown, and the maximum folding angle of the second straight wing 202 is 120 degrees.

[0047] The surfaces of the first straight wing 201 and the second straight wing 202 are covered with solar photovoltaic thin films, and the electric energy collected by the solar photovoltaic thin films will be stored in a large-capacity lithium battery located in the power cabin 103.

[0048] Among the three power components, one is fixed directly below the power cabin 103, and the other two are symmetrically fixed above the power cabin 103. The fixed angular interval between the three power components is 120°, and the total maximum available pulling force provided by the power components is not less than the takeoff weight of the unmanned aircraft.

[0049] As Figure 5 shown, two motors 303 facing each other are arranged axially inside the duct 301. Each motor 303 is connected to a corresponding propeller 302. The propeller 302 is a two-blade propeller that meets the pulling force requirements, with a model number of 2788 and an installation method of coaxial counter-rotation. Such a design can make the upper and lower propellers' counter-torques cancel each other out when the power component works, avoiding unstable attitudes of the aircraft.

[0050] The inner wall of the duct 301 is provided with an annular cut groove 304 for suppressing the propeller tip vortex, and the outer wall of the duct 301 is provided with a streamlined airfoil structure 305 for lift augmentation to improve the aerodynamic performance of the aircraft.

[0051] The fuselage 1 of the aircraft is designed to be streamlined with a left-right symmetric cross-section. The tail wing component and the power component are axially coincident to maximize the control surface control effect. The aileron 203 and the tail fin rudder 402 can be deflected under the drive of the servo and the transmission mechanism.

[0052] As Figure 6 shown, the mission execution process of the aircraft of the present invention is divided into seven stages: ground preparation, vertical takeoff, vertical-to-horizontal mode switching, mission cruise, horizontal-to-vertical mode switching, vertical landing, and ground recovery. The control method for each stage is as follows:

[0053] Ground preparation: The aircraft is rapidly deployed through modular assembly. After the deployment of the aircraft is completed, relevant system tests are carried out and it enters the waiting-to-fly state. At this time, the fuselage should be perpendicular to the ground, and the foldable wing components are in the folded state;

[0054] Vertical takeoff: Start the motor and keep it idling. After confirming normal operation, adjust the motor speeds of each power component. After the thrust is greater than the gravity, the aircraft leaves the ground and begins to accelerate upward. Before the flight speed reaches the specified mode switching speed, the foldable wing components always remain in the folded state, and the position and attitude of the aircraft are controlled by adjusting the motor speeds of each power component. When the aircraft enters the target altitude range and the flight speed is greater than the specified mode switching speed, the foldable wing components unfold, and the aircraft enters the mode switching stage;

[0055] Vertical-to-level mode switching: Generate a pitching moment on the airframe by adjusting the motor speeds of each power component and the tail fin control surface, and adjust the pitch angle from 90° during vertical ascent to the trim value in the cruise state. During this process, the flight altitude of the aircraft gradually stabilizes until a cruise flight state is finally established.

[0056] Mission cruise: The thrust magnitudes of each power component always remain equal during this stage. The attitude control of the aircraft is only determined by the control amounts of each control surface. The specific control method is to achieve the yaw and pitch movements of the aircraft through the tail fin control surface, and to control the roll movement of the aircraft through the ailerons;

[0057] Level-to-vertical mode switching: Generate a pitching moment on the airframe by adjusting the motor speeds of each power component and the tail fin control surface, and adjust the pitch angle from the trim value in the cruise state to 90° for vertical landing. During this process, the flight altitude of the aircraft gradually rises until a hovering flight state is finally established;

[0058] Vertical landing: After completing the level-to-vertical mode switching, fold the foldable wing components of the aircraft, and control the position and attitude of the aircraft by adjusting the motor speeds of each power component to gradually lower the altitude of the aircraft;

[0059] Ground recovery: When the aircraft completes the mission and lands on the ground, perform relevant maintenance, disassembly, and transportation.

[0060] The above-described embodiments have detailed the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, supplements, and equivalent replacements made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tailstock type three-ducted vertical takeoff and landing aircraft, comprising an aircraft fuselage (1), characterized in that, The front section of the aircraft fuselage (1) is an on-board equipment compartment (101), the middle section is a payload compartment (102), and the rear section is a power compartment (103); On both sides of the payload compartment (102), a pair of foldable wing components (2) are symmetrically arranged. Each foldable wing component (2) includes a first straight wing (201) fixed to the outer wall of the payload compartment (102), a second straight wing (202) foldably fixed to the first straight wing (201), and ailerons (203) arranged on the second straight wing (202); On the outer wall of the power compartment (103), three power components (3) are evenly fixed along the circumferential direction. Each power component (3) includes a duct (301) fixed to the outer wall of the power compartment (103), a motor (303) fixed in the duct (301), and a propeller (302) connected to the output end of the motor (303); At the tail end of the power compartment (103), a plurality of tail wing components (4) are evenly fixed. Each tail wing component (4) includes a tail wing (401) fixed to the tail end of the power compartment (103), a tail wing rudder (402) arranged on the tail wing (401), and a landing gear (403) arranged at the end of the tail wing (401); In the on-board equipment compartment (101), a flight controller and other on-board equipment for controlling the foldable wing components (2), power components (3), and tail wing components (4) are provided, which are used to control the flight process of the aircraft; The aircraft fuselage (1) is designed to be streamlined with a left-right symmetric cross-section, and the installation angles of the tail wing components and the power components are kept consistent.

2. The tailstock type three-ducted vertical takeoff and landing aircraft according to claim 1, characterized in that, On the payload compartment (102), a dorsal hatch (1021) and a ventral hatch (1022) are provided.

3. The tailstock type three-ducted vertical takeoff and landing aircraft according to claim 1, characterized in that, The airfoils of the first straight wing (201) and the second straight wing (202) are both NACA6412, and the two are connected by a hinge; the second straight wing (202) is in a folded state during vertical flight of the aircraft and in an unfolded state during horizontal flight; among them, the maximum folding angle of the second straight wing (202) is 120 degrees.

4. The tailstock type three-ducted vertical takeoff and landing aircraft according to claim 1, characterized in that, The surfaces of the first straight wing (201) and the second straight wing (202) are covered with solar photovoltaic thin films, and the electric energy collected by the solar photovoltaic thin films is stored in a large-capacity lithium battery located in the power compartment (103).

5. The tailstock type three-ducted vertical takeoff and landing aircraft according to claim 1, characterized in that, Among the three power components, one is fixed directly below the power compartment (103), and the other two are symmetrically fixed above the power compartment (103). The fixed angular intervals between the three power components are 120°, and the total maximum available pull provided by the power components is not less than the take-off weight of the unmanned aircraft.

6. The tailstock type three-ducted vertical takeoff and landing aircraft according to claim 1, characterized in that, Inside the duct (301), two opposed motors (303) are arranged along the axial direction. Each motor (303) is connected to a corresponding propeller (302). The propeller is a two-blade propeller that meets the pull requirement, with a model of 2788, and the installation method is coaxial counter-rotation.

7. The tailstock type three-ducted vertical takeoff and landing aircraft according to claim 1, characterized in that, On the inner wall of the duct (301), an annular cut groove (304) for suppressing the tip vortex of the propeller is provided. The ratio of the depth of the groove to the length of the part of the blade immersed is 2:

1. On the outer wall of the duct (301), a streamlined airfoil structure (305) for lift enhancement is provided.

8. A control method for the tailstock type three-ducted vertical takeoff and landing aircraft according to any one of claims 1 to 7, characterized in that, The mission execution process of the aircraft is divided into seven stages: ground preparation, vertical takeoff, vertical-to-horizontal mode switching, mission cruise, horizontal-to-vertical mode switching, vertical landing, and ground recovery. The control methods for each stage are as follows: Ground preparation: The aircraft achieves rapid deployment through modular assembly. After the aircraft completes deployment, relevant system tests are carried out and it enters the ready-to-fly state. At this time, the fuselage (1) should be perpendicular to the ground, and the foldable wing components (2) are in the folded state; Vertical takeoff: Start the motor and keep it idling. After confirming normal operation, adjust the motor speeds of each power component (3). After the thrust is greater than the gravity, the aircraft leaves the ground and begins to accelerate upward. Before the flight speed reaches the specified mode switching speed, the foldable wing components (2) always remain in the folded state, and the position and attitude of the aircraft are regulated by adjusting the motor speeds of each power component (3). When the aircraft enters the target altitude range and the flight speed is greater than the specified mode switching speed, the foldable wing components (2) unfold, and the aircraft enters the mode switching stage; Vertical-to-horizontal mode switching: Generate a pitching moment on the airframe by adjusting the motor speeds of each power component (3) and the tail fin control surfaces, and adjust the pitch angle from 90° during vertical ascent to the trim value in the cruise state. During this process, the flight altitude of the aircraft gradually stabilizes until finally a cruise flight state is established; Mission cruise: The thrust magnitudes of each power component (3) always remain equal in this stage. The attitude control of the aircraft is only determined by the control amounts of each control surface. The specific control method is to achieve the yaw and pitch movements of the aircraft through the tail fin control surfaces, and control the roll movement of the aircraft through the ailerons; Horizontal-to-vertical mode switching: Generate a pitching moment on the airframe by adjusting the motor speeds of each power component (3) and the tail fin control surfaces, and adjust the pitch angle from the trim value in the cruise state to 90° for vertical landing. During this process, the flight altitude of the aircraft gradually rises until finally a hovering flight state is established; Vertical landing: After completing the horizontal-to-vertical mode switching, fold the foldable wing components (2) of the aircraft, and regulate the position and attitude of the aircraft by adjusting the motor speeds of each power component (3) to gradually lower the altitude of the aircraft; Ground recovery: When the aircraft completes the mission and lands on the ground, carry out relevant maintenance and disassembly and transportation.

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