Vertical take-off and landing aircraft and control method thereof

Abstract

The invention provides a vertical take-off and landing aircraft and a control method thereof. The vertical take-off and landing aircraft comprises a fuselage and 2N tilting rotors. Wings are arranged on the two sides of the fuselage, an empennage is arranged at the tail of the fuselage, and a lifting rudder is arranged on the empennage; the 2N tilting rotors are symmetrically mounted on the two sides of the fuselage, and one part of the 2N tilting rotors is located on the empennage; wherein N is a natural number larger than or equal to 2, in the vertical take-off and landing state, the projections of the propellers of the 2N tilt rotors on the horizontal plane are in central symmetry about the point B, the point B and the gravity center G point of the vertical take-off and landing aircraft are both located in the symmetry plane of the aircraft body, and the point B is located on the side, close to the empennage, of the point G; in the transition process of the vertical take-off and landing aircraft from the vertical take-off and landing state to the cruise state, the G point and the B point move towards the side close to the nose along the symmetric face, and the B point is always located on the side, close to the empennage, of the G point. By means of the layout, the vertical take-off and landing aircraft can have the good balancing pitching capacity.

Description

[0001] This application is a divisional application of application No. 202311677618.7, titled "Vertical Take-off and Landing Aircraft and Control Method Thereof", filed on December 7, 2023. TECHNICAL FIELD

[0002] The present application relates to the technical field of aircraft, in particular to a vertical take-off and landing aircraft and a control method thereof. BACKGROUND

[0003] The vertical take-off and landing fixed-wing aircraft (distributed propulsion type) has both the vertical take-off and landing capability of a helicopter and the horizontal high-efficiency and high-speed flight capability of a fixed-wing aircraft, and is more quiet, comfortable and economical than a helicopter, more efficient and longer in range than a multi-rotor aircraft, and can vertically take off and land on a landing platform in the city, which is an excellent choice for urban air travel. However, in the existing vertical take-off and landing aircraft, when the rotor is arranged on the tail, the airflow generated by the rotor and the airflow generated by the tail interfere with each other, which easily causes difficulty in pitch control, which will bring unpredictable technical difficulties to the flight control of the vertical take-off and landing aircraft. SUMMARY

[0004] In view of the above shortcomings of the prior art, the present application provides a vertical take-off and landing aircraft and a control method thereof to improve the problem that the airflow interference between the tilting rotor on the tail and the tail is large in the existing vertical take-off and landing aircraft, and it is not easy to perform pitch control.

[0005] To achieve the above object and other related objects, the present application provides a vertical take-off and landing aircraft, comprising: a fuselage and 2N tilting rotors. The fuselage is provided with wings on both sides, the tail of the fuselage is provided with a tail, and the tail is provided with an elevator; 2N tilting rotors are symmetrically installed on both sides of the fuselage, and a part of the 2N tilting rotors are located on the tail; wherein N is a natural number greater than or equal to 2, in the vertical take-off and landing state, the projections of the 2N tilting rotors on the horizontal plane are centrally symmetric about point B, the point B and the gravity center G of the vertical take-off and landing aircraft are located in the symmetry plane of the fuselage, and the point B is located on the side of the point G close to the tail, in the process of mode change of the vertical take-off and landing aircraft, the points G and B move along the symmetry plane, and the point B is always located on the side of the point G close to the tail.

[0006] In an embodiment of the vertical take-off and landing aircraft of the present application, in the flight process, the rotation axis of any tilting rotor on the tail and the rotation axis of any tilting rotor at other positions have projections on the symmetry plane of the fuselage that are not parallel.

[0007] In an embodiment of the vertical take-off and landing aircraft of the present application, there is a first difference between the tilt speed of any of the tilt rotors on the tail and the tilt speed of any of the tilt rotors at other locations, and the first difference is not equal to 0, during cruising state and / or vertical take-off state and / or modal transition state.

[0008] In an embodiment of the vertical take-off and landing aircraft of the present application, there is a second difference between the rotation speed of any of the tilt rotors on the tail and the rotation speed of any of the tilt rotors at other locations, and the second difference is not equal to 0, during cruising state and / or vertical take-off state and / or modal transition state.

[0009] In an embodiment of the vertical take-off and landing aircraft of the present application, the vertical take-off and landing aircraft employs the following method for pitch control:

[0010] During flight, the elevator and the pitch control proportion of 2N tilt rotors are distributed according to the current airspeed or dynamic pressure;

[0011] According to the pitch control proportion, the elevator and 2N tilt rotors are controlled respectively to achieve pitch trim and control.

[0012] In an embodiment of the vertical take-off and landing aircraft of the present application, controlling 2N tilt rotors according to the pitch control proportion includes:

[0013] The tilt angle difference between the tilt rotors on the tail and any other tilt rotors is used to differentially adjust the pitch moment to achieve pitch trim and control;

[0014] And / or, the rotation speed difference between the tilt rotors on the tail and any other tilt rotors is used to differentially adjust the pitch moment to achieve pitch trim and control;

[0015] And / or, the tilt speed difference between the tilt rotors on the tail and any other tilt rotors is used to differentially adjust the pitch moment to achieve pitch trim and control.

[0016] In an embodiment of the vertical take-off and landing aircraft of the present application, the vertical take-off and landing aircraft includes four tilt rotors, two of which are symmetrically mounted on the wings about the fuselage, and the other two are symmetrically mounted on the tail.

[0017] In an embodiment of the vertical take-off and landing aircraft of the present application, the vertical take-off and landing aircraft includes six tilt rotors, four of which are symmetrically mounted on the wings about the fuselage, and the other two are symmetrically mounted on the tail.

[0018] In an embodiment of the vertical take-off and landing aircraft, the tail is a V-tail, and two of the tilt rotors are full-tilt rotors mounted on the wing tips of the V-tail.

[0019] In an embodiment of the vertical take-off and landing aircraft, two of the tilt rotors are mounted on the wing tips of the wings, and the tilt rotors mounted on the wing tips of the wings are full-tilt rotors.

[0020] In an embodiment of the vertical take-off and landing aircraft, the vertical take-off and landing aircraft further comprises 2M fixed rotors, M being a natural number greater than or equal to 2, and the 2M fixed rotors are symmetrically mounted on the wings on both sides of the fuselage and located outside the tilt rotors; in the vertical take-off and landing state, the projections of all the fixed rotors on the horizontal plane are centrally symmetric about point A, the point A is located in the symmetry plane of the fuselage, and in the process of mode change of the vertical take-off and landing aircraft, point G is located on the side of point A close to the nose or coincides with point A, and point B is always located on the side of point A close to the tail.

[0021] In an embodiment of the vertical take-off and landing aircraft, the vertical take-off and landing aircraft is controlled in pitch by the following method:

[0022] In the process of flight, the pitch control proportion of the elevators, the 2N tilt rotors and the 2M fixed rotors is allocated according to the current airspeed or dynamic pressure;

[0023] According to the pitch control proportion, the elevators, the 2N tilt rotors and the 2M fixed rotors are controlled respectively to realize pitch trim and control.

[0024] In an embodiment of the vertical take-off and landing aircraft, four of the fixed rotors are symmetrically mounted on both sides of the fuselage, four of the tilt rotors are located inside the four fixed rotors, and two of the tilt rotors are symmetrically mounted on the tail.

[0025] In an embodiment of the vertical take-off and landing aircraft, the tail is a V-tail, the V-tail is mounted with two of the tilt rotors, the two tilt rotors are respectively mounted on the wing tips of the V-tail, and in the vertical take-off and landing state, the distance between the rotation center of the tilt rotors on the tail and the leading edge of the wing tip of the V-tail is t1 in the direction parallel to the roll axis of the vertical take-off and landing aircraft, and the chord length of the wing tip of the V-tail is t2, wherein the ratio of t1 to t2 is 15% to 40%.

[0026] In an embodiment of the vertical take-off and landing aircraft, the tilt-rotor on the tail is a full tilt-rotor; the tilt-rotor outside the tail is a partial tilt-rotor.

[0027] In an embodiment of the vertical take-off and landing aircraft, a tilt-rotor is arranged on the wing tip of the wing, the tilt-rotor on the tail and the tilt-rotor on the wing tip of the wing are full tilt-rotors.

[0028] In an embodiment of the vertical take-off and landing aircraft, the full tilt-rotor comprises a first rotor and a power pod, the first rotor is connected to the power pod, the power pod is rotationally connected to the tail or the wing, and the power pod is synchronously tilted with the first rotor during the tilting of the first rotor.

[0029] In an embodiment of the vertical take-off and landing aircraft, the elevator comprises an elevator plate and an elevator body driving device, the elevator plate is rotationally connected to the tail or the tail of the fuselage, and the elevator body driving device drives the rotation of the elevator plate to adjust the direction of the vertical take-off and landing aircraft.

[0030] The application also provides a control method of a vertical take-off and landing aircraft, the vertical take-off and landing aircraft comprising a fuselage and 2N tilt-rotors. Wings are arranged on both sides of the fuselage, a tail is arranged at the tail of the fuselage, and an elevator is arranged on the tail. 2N tilt-rotors are symmetrically installed on both sides of the fuselage, and a part of the 2N tilt-rotors are located on the tail. N is a natural number greater than or equal to 2. In the vertical take-off and landing state, the projections of the propellers of the 2N tilt-rotors on the horizontal plane are centrally symmetric about point B, the point B and the gravity center G of the vertical take-off and landing aircraft are located on the symmetry plane of the fuselage, and the point B is located on the side of the gravity center G close to the tail. During the mode change of the vertical take-off and landing aircraft, the gravity center G and the point B move along the symmetry plane. Specifically, during the transition of the vertical take-off and landing aircraft from the vertical take-off and landing state to the cruising state, the gravity center G and the point B move along the symmetry plane to the side close to the nose, and the point B is always located on the side of the gravity center G close to the tail. The control method comprises the following pitch control process:

[0031] According to the current airspeed or dynamic pressure, the pitch control proportion of the elevator and the 2N tilt-rotors is allocated.

[0032] According to the pitch control proportion, the elevator and the 2N tilt-rotors are controlled respectively to realize pitch trim and control.

[0033] In an embodiment of the control method, the rotor control process further comprises the following steps before the step of distributing the elevator and the pitch control proportion of the 2N tilt rotors according to the current airspeed or dynamic pressure:

[0034] obtaining the current tilt position of each tilt rotor;

[0035] if the current tilt position is inconsistent with the set cruising position, obtaining the current airspeed or dynamic pressure of the corresponding tilt rotor at the current tilt position, and determining whether the current airspeed or dynamic pressure is equal to or greater than a preset threshold at the current tilt position;

[0036] if the current airspeed or dynamic pressure is equal to or greater than the preset threshold at the current tilt position, controlling the tilt rotor to tilt to a preset next position;

[0037] gradually increasing the rotational speed of the 2N tilt rotors.

[0038] In an embodiment of the control method, the VTOL aircraft further comprises 2M fixed rotors, M being a natural number greater than or equal to 2; the 2M fixed rotors are distributed around the 2N tilt rotors, and in the process of gradually increasing the rotational speed of the 2N tilt rotors, the rotor control process further comprises gradually reducing the rotational speed of the 2M fixed rotors to a set rotational speed.

[0039] In an embodiment of the control method, the rotor control process further comprises the following take-off control process before the rotor control process:

[0040] tilting the 2N tilt rotors to the vertical upward or inclined upward of the rotation axis;

[0041] deflecting the elevator downward;

[0042] starting the 2M fixed rotors and the 2N tilt rotors, and issuing a flat flying instruction when the VTOL aircraft reaches a set height.

[0043] In an embodiment of the control method, the VTOL aircraft further comprises 2M fixed rotors, and the 2M fixed rotors are distributed around the 2N tilt rotors, and the rotor control process further comprises the following take-off control process before the step of distributing the elevator and the pitch control proportion of the 2N tilt rotors according to the current airspeed or dynamic pressure:

[0044] tilting the 2N tilt rotors to the horizontal forward of the rotation axis;

[0045] deflecting the elevator downward;

[0046] starting the 2M fixed rotors and the 2N tilt rotors, and issuing a flat flying instruction when the VTOL aircraft reaches a set height.

[0047] In an embodiment of the control method, after the take-off control process, the pitch control process further comprises: gradually increasing the rotating speed of the 2N tilting rotors, issuing a forward flight instruction, and gradually reducing the rotating speed of the 2M fixed rotors to a set rotating speed.

[0048] In an embodiment of the control method, after the rotating speed of the 2M fixed rotors is gradually reduced to the set rotating speed in the rotor control process, the control method further comprises: controlling the elevators to return to zero according to the current airspeed or dynamic pressure, and gradually participating in the pitch control process.

[0049] In an embodiment of the control method, before the take-off control process, the control method further comprises a ground preparation process, and the ground preparation process comprises: starting the vertical take-off and landing aircraft, detecting system power-on, and confirming full stroke state of the servo system.

[0050] In an embodiment of the control method, according to the pitch control proportion, the elevators and the 2N tilting rotors are controlled respectively to realize pitch trim and control, which comprises: differentiating the tilting speed difference and / or the tilting angle difference between the tilting rotors in different directions of the center of gravity and / or the rotating speed difference of the tilting rotors to differentially adjust the pitch moment to realize pitch trim and control.

[0051] In an embodiment of the control method, the control method further comprises: sequentially repeating the rotor control process and the pitch control process until the tilting rotors are tilted to a cruising position, and completing the take-off transition flight.

[0052] The vertical take-off and landing aircraft is provided with elevators and 2N tilt rotors, in the vertical take-off state, the projections of the 2N tilt rotors on the horizontal plane are centrally symmetric about the point B, the point B and the gravity center G of the vertical take-off and landing aircraft are located in the symmetry plane of the fuselage, and the point B is located on the side of the gravity center G close to the tail. And during the mode change of the vertical take-off and landing aircraft, the point B is always located on the side of the gravity center G close to the tail. With this layout, the gravity center G of the vertical take-off and landing aircraft and the symmetry center B of the tilt rotors are not coincident, especially during the transition of the vertical take-off and landing aircraft from the vertical take-off state to the cruising state, the gravity center G and the symmetry center B are both moved along the symmetry plane to the side close to the nose. Therefore, the pulling force of the tilt rotors on the front side of the gravity center has a smaller moment on the gravity center G, the pulling force of the tilt rotors on the rear side of the gravity center has a larger moment on the gravity center G, and the moment difference of the front and rear tilt rotors can resist the part of the lifting moment of the tail caused by the wash flow area of the tilt rotors on the tail, so as to reduce the difficulty of pitch control. Therefore, under the condition that the tilt rotors on the front and rear sides of the gravity center G have the same speed and throttle, a lowering moment can be generated due to the length difference of the force arm on the gravity center G, which can offset or partially offset the lifting moment of the tail caused by the wash flow area of the tilt rotors on the tail, so as to balance the pitch moment of the vertical take-off and landing aircraft under the condition that the front and rear tilt rotors have the same throttle.

[0053] The control method can distribute the elevators and the pitch control proportion of the 2N tilt rotors according to the current airspeed or dynamic pressure, and can realize pitch control through the linkage of the elevators and the 2N tilt rotors. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other embodiments can be obtained without creative labor on the basis of these drawings.

[0055] Figure 1 is the axial side view of the vertical take-off and landing aircraft in the vertical take-off state in an embodiment of the present application;

[0056] Figure 2 is the side view of the vertical take-off and landing aircraft in the vertical take-off state in an embodiment of the present application;

[0057] Figure 3 is the axial side view of the vertical take-off and landing aircraft in the vertical take-off state in another embodiment of the present application;

[0058] Figure 4This is a side view of a vertical takeoff and landing aircraft in a vertical takeoff and landing state, according to another embodiment of the present invention.

[0059] Figure 5 This is an axonometric view of a vertical takeoff and landing aircraft in cruise mode, according to another embodiment of the present invention.

[0060] Figure 6 This is an axonometric view of a vertical takeoff and landing aircraft in a vertical takeoff and landing state, according to another embodiment of the present invention.

[0061] Figure 7 This is a top view of a vertical takeoff and landing aircraft in a vertical takeoff and landing state, according to another embodiment of the present invention.

[0062] Figure 8 This is a side view of a vertical takeoff and landing aircraft in a vertical takeoff and landing state, according to another embodiment of the present invention.

[0063] Figure 9 This is a rear view of a vertical takeoff and landing aircraft in a vertical takeoff and landing state, according to another embodiment of the present invention.

[0064] Figure 10 A partial view of a fully tilt rotor;

[0065] Figure 11 A partial view of the tiltrotor after the pod shell has been removed;

[0066] Figure 12 Top view of a tiltrotor rotor after the pod shell has been removed;

[0067] Figure 13 for Figure 12 Sectional view of DD;

[0068] Figure 14 A view from another angle after the pod shell has been removed from the fully tilting rotor;

[0069] Figure 15 A 3D view of the tiltrotor from another direction after the pod shell has been removed;

[0070] Figure 16 for Figure 14 FF sectional view;

[0071] Figure 17 for Figure 14 PP sectional view;

[0072] Figure 18 This is a partial view of the tail rotor in a vertical position with the chord length of the control plate accounting for 30%.

[0073] Figure 19 This is a partial view of the tail rotor in a vertical position with the chord length of the control plate at 60%.

[0074] Figure 20 Partial view of the tail for the case of full tilt-rotor on the tail in vertical take-off state, with 100% tail-surface chord ratio;

[0075] Figure 21 Partial view of the tail for the case of full tilt-rotor on the tail in cruise state;

[0076] Figure 22 Partial view of the tail for the case of full tilt-rotor on the tail in climb state;

[0077] Figure 23 Rotation path of the tail elevator on the tail;

[0078] Figure 24 Top view of the tail for the case of the VTOL aircraft in vertical take-off state;

[0079] Figure 25 Tail-surface chord ratio and tail-surface deflection angle for the tail;

[0080] Figure 26 Top view of the tail for the case of the VTOL aircraft in vertical take-off state;

[0081] Figure 27 Hovering and transition control method for the tilt-rotor aircraft, variation of the total machine pitch moment (dimensionless) with wind speed (dimensionless) (CFD simulation results);

[0082] Figure 28 Flow chart for the case of the VTOL aircraft in one embodiment of the present application from ground state to cruise state;

[0083] Figure 29 Flow chart for the case of the VTOL aircraft in one embodiment of the present application from take-off to cruise state;

[0084] Figure 30 Flow chart for the case of the VTOL aircraft in one embodiment of the present application in pitch control;

[0085] Figure 31 Flow chart for the case of the VTOL aircraft in one embodiment of the present application in rotor control;

[0086] Figure 32 Flow chart for the case of the VTOL aircraft in one embodiment of the present application in take-off control;

[0087] Figure 33 Flow chart for the case of the VTOL aircraft in one embodiment of the present application in take-off control;

[0088] Figure 34 Top view of the VTOL aircraft in the vertical take-off state for another embodiment of the present application.

[0089] Element number explanation

[0090] 10, fuselage; 20, wing; 30, tail; 31, elevator; 311, plate; 41, first tilt-rotor; 411, third arm; 42, second tilt-rotor; 421, fourth arm; 43, third tilt-rotor; 44, fourth tilt-rotor; 441, first rotor; 4411, propeller; 4412, rotary drive; 4413, spinner; 442, power pod; 4421, tilt drive; 4422, rocker arm; 4423, first shaft; 4424, second shaft; 4425, embracing structure; 44251, slit; 4426, connecting rod; 4427, first articulation shaft; 4428, second articulation shaft; 4429, drive arm; 4430, bearing; 51, first fixed rotor; 511, first arm; 52, second fixed rotor; 521, second arm; 53, third fixed rotor; 54, fourth fixed rotor; 60, plane of symmetry. DETAILED DESCRIPTION

[0091] The present application is herein described, by way of example only, with the assistance of specific details to facilitate a thorough understanding of the application. The description is intended only by way of description of the application and is not intended to limit the scope of the application in any manner. Herein described embodiments can be combined with each other in all possible ways not specifically mentioned in the description. It is to be understood that the terminology used herein is for the purpose of describing the particular embodiments only and is not intended to limit the scope of the application. Unless specifically defined herein, all technical and scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, unless otherwise required by context, singular terms shall include pluralities and vice versa. The description is not intended to limit the scope of the application, as claimed below, to any single aspect or feature of the application.

[0092] When numerical ranges are given, it should be understood that every numerical value between the two endpoints, and any numerical value in between, is also contemplated unless otherwise indicated herein. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of the application, unless otherwise indicated herein.

[0093] It should be noted that the terms such as "upper", "lower", "left", "right", "intermediate", and "one" and the like as used herein are only intended to facilitate the description of the present application and are not intended to limit the scope of the present application, and the change or adjustment of the relative relationship thereof without substantial change in the technical content is also regarded as the scope of the present application.

[0094] Reference should be made to Figures 1 to 34This invention first provides a vertical takeoff and landing (VTOL) aircraft. The VTOL aircraft has 2N tiltrotors symmetrically arranged around its fuselage 10, and an elevator is installed on its tail 30. By utilizing the positional relationship between the 2N tiltrotors and the center of gravity, the pitch moment control of the VTOL aircraft under complex turbulent flow fields can be improved, thereby alleviating the control problems caused by airflow interference between the tiltrotors on the tail 30 and the tail 30 in existing VTOL aircraft.

[0095] Please see Figures 1 to 7 This invention provides a vertical takeoff and landing (VTOL) aircraft, comprising a fuselage and 2N tiltrotor rotors. The fuselage 10 has a symmetrical structure and has a symmetrical plane 60 extending along the length of the fuselage 10 (i.e., Figure 3 The vertical plane containing the center line O1-O2), the remaining structure and shape of the fuselage 10 are not limited and can refer to the structure of the fuselage 10 of existing vertical takeoff and landing aircraft. The fuselage 10 includes conventional aircraft operating systems such as avionics, flight control, electrical, and navigation systems, which will not be described in detail here. Wings 20 are provided on both sides of the fuselage 10. The wings 20 are symmetrical with respect to the plane of symmetry 60 of the fuselage 10. The structure of the wings 20 can also refer to the fixed wing structure of existing aircraft, which will not be described in detail here. A tail fin 30 is provided at the tail of the fuselage 10. The tail fin 30 is integrally formed with the fuselage 10 or mechanically connected, and is symmetrically arranged with respect to the plane of symmetry 60 of the fuselage 10. An elevator 31 is provided on the tail fin 30. The installation position and structure of the elevator fin 31 can be various, for example, it can be set in any suitable position on the tail fin 30, or it can be any suitable existing elevator fin structure.

[0096] Key point, please see Figure 7 2N tiltrotors are mounted on both sides of the fuselage 10, where N is a natural number greater than or equal to 2. These 2N tiltrotors are symmetrically arranged about a plane of symmetry 60 of the fuselage 10, and a portion of these tiltrotors are mounted on the tail fin 30. In vertical takeoff and landing (VTOL) mode, the projections of the propellers of the 2N tiltrotors onto the horizontal plane are centrally symmetrical about point B. Point B and the center of gravity G of the VTOL aircraft are both located within the plane of symmetry of the fuselage, with point B located on the side of point G closer to the tail fin. During mode changes, both points G and B move along the plane of symmetry. For example, during the transition from VTOL to cruise mode, both points G and B move along the plane of symmetry towards the nose, with point B always located on the side of point G closer to the tail fin.

[0097] With the above layout, the center of gravity G of the VTOL aircraft and the center of symmetry B of the 2N tilt rotors do not coincide, and during the transition of the VTOL aircraft from the VTOL state to the cruising state, both G and B move along the symmetry plane 60 to the side close to the nose. Therefore, the moment of the pulling force of the front tilt rotors on the center of gravity G is smaller, and the moment of the pulling force of the rear tilt rotors on the center of gravity G is larger, and the difference in the moments of the front and rear tilt rotors can resist the partial lifting moment of the tail 30 caused by the wash of the tilt rotors on the tail, thus reducing the difficulty of pitch control. Therefore, under the condition that the same speed of the tilt rotors on both sides of the center of gravity G, because of the difference in the length of the force arm on the center of gravity G, a lowering moment is generated, which can offset or partially offset the lifting moment of the tail caused by the wash of the tilt rotors on the tail, thus the VTOL aircraft can be better balanced in pitch moment under the condition that the front and rear rotor oil is consistent.

[0098] The VTOL aircraft of the present application, in various states, such as cruising state of flying along the horizontal direction, vertical take-off state of taking off along the vertical direction, mode conversion state (including conversion from vertical take-off state to cruising state and conversion from cruising state to vertical take-off state), the rotation axes of the tilt rotors can be parallel or not parallel. In some embodiments, during flight, the projection of the rotation axis of any tilt rotor on the tail 30 and the rotation axis of any tilt rotor at other positions on the symmetry plane 60 of the fuselage 10 are not parallel, and through the non-parallel rotation axes, different tilt rotors provide different moments, thereby controlling the pitch moment of the entire VTOL aircraft.

[0099] Although the tilt speed of each tilt rotor can be the same, thereby controlling the pitch through other means, in an embodiment of the VTOL aircraft of the present application, in various states, such as cruising state of flying along the horizontal direction, vertical take-off state of taking off along the vertical direction, mode conversion state (including conversion from vertical take-off state to cruising state and conversion from cruising state to vertical take-off state), the tilt speed of any tilt rotor on the tail 30 and the tilt speed of any tilt rotor at other positions exist a first difference, and the first difference is not equal to 0, and by setting a threshold value of the first difference, the pitch moment of the VTOL aircraft in various states can be adjusted through the tilt of the tilt rotors to obtain a larger pitch control moment.

[0100] In the embodiment of the VTOL aircraft of the present application, in each state, such as the cruising state of flying along the horizontal direction, the vertical take-off state of taking off along the vertical direction, and the mode transition state (including the transition from the vertical take-off state to the cruising state and the transition from the cruising state to the vertical take-off state), the rotation speed of any of the tilt rotors on the tail 30 and the rotation speed of any of the tilt rotors at other positions have a second difference, and the second difference is not equal to 0. By setting a threshold value of the second difference, the pitch force of the VTOL aircraft in each state can be adjusted by the rotation speed of the tilt rotors to obtain a larger pitch control moment. It should be noted that the first difference of the rotation speed of the front tilt rotors (the tilt rotors located on the front side of the tilt rotors on the tail 30) and the tilt rotors on the tail 30 can be combined with the second difference of the rotation speed of the front tilt rotors and the tilt rotors on the tail 30 to achieve various strategies of pitch moment control.

[0101] Although the present application can be as described above Figures 1 to 4 and only include 2N tilt rotors, preferably, please refer to Figure 7 In another embodiment of the present application, the VTOL aircraft includes 2M fixed rotors, M is a natural number greater than or equal to 2, and M can have the same value as N or a different value. The 2M fixed rotors are symmetrically installed on the wings on both sides of the fuselage and located outside the tilt rotors; in the vertical take-off state, the projections of all the fixed rotors on the horizontal plane are centrally symmetric about point A, the point A is located in the symmetry plane of the fuselage, and coincides with the point G or is located on the side of the point G close to the tail. During the transition of the VTOL aircraft from the vertical take-off state to the cruising state, the points G and B move along the symmetry plane to the side close to the nose, and the point G is located on the side close to the nose of the point A or coincides with the point A, and the point B is always located on the side close to the tail of the point A.

[0102] Specifically, the center B point of the 2N tilting rotors is located at the rear side of the center A point of the 2M fixed rotors with the nose of the VTOL aircraft facing forward, and the distance from the A point to the B point is L2, L2>0. As the 2N tilting rotors tilt forward, the center of gravity of the 2N tilting rotors, the center of gravity G of the VTOL aircraft, and the center of symmetry B point will move towards the nose direction. During the entire tilting process from the preset VTOL position (for example, a 90° tilting angle) of the 2N tilting rotors to the preset cruising position (for example, a 0° tilting angle), L2>0 is always true. At the same time, the center of gravity G of the VTOL aircraft is located at the front side of the center of symmetry B of the 2N tilting rotors, and also at the front side of the center of symmetry A point of the 2M fixed rotors. The distance from the A point to the G point is L1, L1≥0. As the 2N tilting rotors tilt forward, the center of gravity G gradually moves forward, and the absolute value of L1 also becomes larger and larger. In this layout, the center of gravity of the VTOL aircraft and the center of symmetry of the fixed rotors or the center of symmetry of the tilting rotors do not coincide, and during the transition of the VTOL aircraft from the VTOL state to the cruising state, both the G point and the B point move towards the side of the nose along the symmetry plane, and the G point is located at the side of the nose of the A point or coincides with the A point, and the B point is always located at the side of the tail 30 away from the nose of the A point. Therefore, the moment of the pulling force generated by the tilting rotors and the fixed rotors on the front side of the center of gravity is smaller, and the moment of the pulling force generated by the tilting rotors and the fixed rotors on the rear side of the center of gravity is larger. The difference in the moments of the front and rear rotors can resist part of the lifting moment of the tail caused by the wash flow area of the tilting rotors on the tail, thereby reducing the difficulty of pitch control. Therefore, under the condition that the fixed rotors or tilting rotors on the front and rear sides of the center of gravity G have the same rotating speed and oil quantity, a lowering moment can be generated due to the difference in the length of the force arm on the center of gravity G, which can offset or partially offset the lifting moment of the tail caused by the wash flow area of the tilting rotors on the tail. Therefore, the VTOL aircraft can be better balanced in pitch moment under the condition that the oil quantity of the front and rear rotors is consistent.

[0103] Further, during the tilting conversion stage of the tilting rotors, the VTOL aircraft will also generate an additional large lifting moment due to aerodynamic interference. During the tilting process of the tilting rotors, the center of gravity G of the VTOL aircraft gradually moves towards the nose direction, and the center of symmetry B point of the tilting rotors also gradually moves towards the nose direction. Since the center of gravity G is always located in front of the B point, the difference in the moments of the tilting rotors on the front and rear sides of the center of gravity G can also generate a part of the lowering moment to offset or partially offset the lifting moment caused by the aerodynamic interference.

[0104] Further, in the tilting phase and the cruising phase, the center of gravity G is close to the front side relative to points A and B, and point B is always located on the side of point A close to the tail 30, thus having a relatively large longitudinal and heading static stability margin, and the aircraft has stronger resistance to extreme wind weather and safer flight.

[0105] Please refer to Figure 26 In an embodiment of the vertical take-off and landing aircraft of the present application, the tail 30 is a V-tail, a third tilting rotor 43 is installed on the wing tip of one side of the V-tail, and a fourth tilting rotor 44 is installed on the wing tip of the other side of the V-tail, and the third tilting rotor 43 and the fourth tilting rotor 44 are symmetrical about the body symmetry plane 60. In the vertical take-off and landing state, the distance between the rotation center of the tilting rotor on the tail and the leading edge of the wing tip of the V-tail is t1 in the direction parallel to the rolling axis X of the aircraft, and the chord length of the wing tip of the V-tail is t2, wherein the ratio of t1 to t2 is 15% to 40%. According to the stress analysis of the wing tip structure strength of the tail 30, the tilting mechanism is connected to the wing tip of the tail 30 within this range, the thickness of the tail 30 is relatively thick, and the stress condition of the tail 30 is better.

[0106] In an embodiment of the vertical take-off and landing aircraft of the present application, the tilting rotors on the tail are full tilting rotors; the tilting rotors outside the tail are partial tilting rotors, and in other embodiments, the tilting rotors outside the tail can also be full tilting rotors, especially when the tilting rotors are installed on the wing tips, the tilting rotors on the wing tips can also be full tilting rotors. The existing tilting rotors mostly include rotors and power nacelles 442, and motors and control components can be installed in the power nacelles 442. The above-mentioned "partial tilting rotors" mostly cut off the power nacelles 442, and in the process of tilting the rotors, the part close to the rotor tilts with the rotor, and the part away from the rotor is relatively fixed with the body 10. In the above-mentioned "full tilting rotors", the entire power nacelle 442 tilts with the corresponding rotor. It should be noted that if the installation conditions permit, 2N tilting rotors can all be full tilting rotors, but considering that the existing tilting rotors on the front side of the tail 30, the body 10 or the wing 20 are mostly installed on the arms. Please refer to Figures 1 to 6 In an embodiment of the present application, the tilting rotors on the tail 30 are full tilting rotors, and the tilting rotors on the front side of the body 10 or the wing 20 of the tail 30 are partial tilting rotors. The specific position and installation method of the partial tilting rotors on the wing 20 or the body 10 can not be limited. For example, they can be directly installed on the wing 20, or they can be installed on the wing 20 or the body 10 through arms.

[0107] The 2N tilting rotors are symmetrically arranged around the fuselage 10, and the tilting rotors arranged on the tail wing 30 are full-tilting rotors. Since the full-tilting rotors are rotatably installed on the tail wing 30 through the power pod 442, when the full-tilting rotors are tilted, the power pod 442 is synchronously tilted, the power pod 442 on the tail wing 30 is always on the same rotation axis as the rotors, which makes the vertical take-off and landing aircraft have a smaller shielding area of the power pod 442 in the corresponding rotor when hovering, a smaller area of the rotor downwash flow hitting the tail wing 30, less mutual interference between the airflow generated by the rotor and the airflow generated by the tail wing 30, a lower head-lifting moment of the aircraft when hovering, and a simpler control of the pitch moment of the vertical take-off and landing aircraft in a complex interference flow field.

[0108] The full-tilting rotor structure in the application can be any tilting rotor structure that can realize the synchronous tilting of the power pod 442 with the rotor, please refer to Figure 10 and Figure 18 In an embodiment of the vertical take-off and landing aircraft, the full-tilting rotor includes a first rotor 441 and a power pod 442, the first rotor 441 is connected to the power pod 442, the power pod 442 is rotatably connected to the tail wing 30 or the wing 20, and synchronously tilts with the first rotor 441 during the tilting of the first rotor 441. The shell of the power pod 442 contains a power device, for example, if it is a pure electric configuration, it can contain a motor, an electric control, a ring control device, a tilting mechanism, etc.; if it is an oil-driven configuration, the pod contains an engine, an ECU, a tilting mechanism, etc. Of course, the preferred scheme is a pure electric configuration.

[0109] Please refer to Figure 10 In an embodiment of the vertical take-off and landing aircraft, the first rotor 441 is provided with a fairing 4413 at the center, the fairing 4413 is installed on the windward side of the first rotor 441 and is used to reduce air resistance, preferably, the projection of the fairing 4413 covers the projection of the power pod 442 along the extension direction of the rotation axis of the first rotor 441. In this way, the influence of the power pod 442 on the rotor downwash area can be reduced during flight. However, those skilled in the art can understand that the projection of the power pod 442 can also be partially located in the projection of the fairing 4413, which can also partially reduce the resistance, but the effect is weaker than the full coverage of the former.

[0110] The outer shape of the power nacelle 442 includes, but is not limited to, a spheroid, a cuboid, an ellipsoid, etc. Preferably, in an embodiment of the vertical take-off and landing aircraft of the present application, the power nacelle 442 is a spheroid structure, the rotation axis of the spheroid structure is coaxially arranged with the rotation axis of the first rotor 441; the surface of the power nacelle 442 is arranged in a streamlined manner. In this way, the influence of the power nacelle 442 on the corresponding rotor downwash flow area during flight can be reduced.

[0111] Please refer to Figures 10 to 17, the first rotor 441 comprises a propeller 4411 and a rotary driving device 4412, the propeller 4411 is installed on the output shaft of the rotary driving device 4412, the power nacelle 442 comprises a nacelle shell 4431 and a tilting mechanism in the nacelle shell 4431, the tilting mechanism drives the rotary driving device 4412 to tilt. The tilting mechanism in the application can be any suitable type of tilting mechanism that can drive the power nacelle 442 and the rotary driving device 4412 to tilt synchronously, preferably, in the embodiment, the tilting mechanism comprises a rocker arm 4422, a driving arm 4429, a tilting driving device 4421 and a connecting rod 4426. The tilting driving device 4421 can be any suitable structure type with a rotary output shaft, for example, a steering wheel, a combination of a steering wheel and a speed reducer, etc., the tilting driving device 4421 in the application is a steering wheel. The rocker arm 4422 is rotatably installed on the tail wing 30, one end of the rocker arm 4422 close to the rotary driving device 4412 is fixedly connected with the rotary driving device 4412; the driving arm 4429 is rotatably installed on the tail wing 30, and the rotation shaft of the driving arm 4429 is arranged in parallel with the rotation shaft of the rocker arm 4422; the seat body of the tilting driving device 4421 is fixedly installed on the tail wing 30, the driving end of the tilting driving device 4421 drives the driving arm 4429 to rotate; one end of the connecting rod 4426 is hinged with the rocker arm 4422 through a first hinge shaft 4427, the other end of the connecting rod 4426 is hinged with the driving arm 4429 through a second hinge shaft 4428, although the first hinge shaft 4427 and the second hinge shaft 4428 can also be installed without bearings 4430, preferably, bearings 4430 are arranged between the connecting rod 4426 and the first hinge shaft 4427, and bearings 4430 are also arranged between the connecting rod 4426 and the second hinge shaft 4428, so that the tilting process is more stable. The above-mentioned tilting mechanism can realize the double-shaft connection structure with the tail wing 30 through the rotation shaft of the rocker arm 4422 and the rotation shaft of the driving arm 4429, the moment borne by the tilting mechanism can be increased to reduce the force borne by the single rod by increasing the shaft spacing between the rotation shaft between the rocker arm 4422 and the tail wing 30 and the rotation shaft between the driving arm 4429 and the tail wing 30, the torsional resistance of the mechanism is stronger, and the support stiffness of the mechanism is improved. And this kind of setting can use the single-sided support mode, fix the tilting mechanism on the aircraft, reduce the driving demand through the four-bar linkage, and also can conveniently adjust the stiffness and the natural frequency of the whole mechanism by adjusting the length ratio between the four-bar linkages.

[0112] Please refer to Figures 11 to 17Preferably, in the embodiment, the tail wing 30 is fixedly provided with a first shaft body 4423 and a second shaft body 4424 parallel to each other, one end of the first shaft body 4423 and the second shaft body 4424 is fixed on the wing tip of the tail wing 30, the other end of the first shaft body 4423 and the second shaft body 4424 is cantilevered, the rocker arm 4422 is rotatably installed on the first shaft body 4423 through a bearing 4430, the driving arm 4429 is rotatably installed on the second shaft body 4424 through a bearing 4430, the seat body of the tilting driving device 4421 is rotatably installed on the first shaft body 4423 through a clamping structure 4425 and is positioned along the axial direction of the first shaft body 4423, and the driving end of the tilting driving device 4421 is coaxial with the second shaft body 4424 and is fixedly connected with the driving arm 4429. In this way, on the one hand, the clamping structure 4425 and the second shaft body 4424 can jointly realize the positioning installation of the tilting driving device 4421, and on the other hand, the installation difficulty of the tilting mechanism in the power pod 442 shell can be reduced, and the single-side installation stability of the full-tilt rotor can be improved. It should be noted that in other embodiments, the tilting driving device 4421 can also be fixedly arranged on the tail wing 30, and the output shaft of the tilting driving device 4421 can be extended to be fixedly connected with the driving arm 4429, so as to drive the rocker arm 4422 to tilt. However, compared with the embodiment, this arrangement mode occupies a larger space inside the tail wing 30, is not suitable for the case that the wing type is thin or there are many internal devices, and finally causes the torque borne by the tilting driving device 4421 to be borne by the installation seat of the tilting driving device 4421, which has a higher requirement on the installation strength of the tilting driving device 4421.

[0113] Please refer to Figures 11 to 17 The first shaft body 4423 and the second shaft body 4424 can also be limited by the clamping structure 4425 to each other, so as to strengthen the structural strength of the first shaft body 4423 and the second shaft body 4424 arranged on the tail wing 30, maintain the parallel positional relationship of the first shaft body 4423 and the second shaft body 4424 on the tail wing 30, ensure that the driving device and the rocker arm 4422 are maintained on the same horizontal plane during the tilting driving process, and realize the stable tilting driving of the driving device to the rocker arm 4422. One end of the clamping structure 4425 is fixedly connected with the seat body of the tilting driving device 4421, specifically, the one end of the clamping structure 4425 is arranged around the periphery of the seat body of the tilting driving device 4421, more specifically, the one end of the clamping structure 4425 is fixedly connected with the seat body of the tilting driving device 4421 and is coaxially installed on the second shaft body 4424; the other end of the clamping structure 4425 is clamped around the first shaft body 4423, specifically, as shown in Figure 15As shown, the other end of the embracing structure 4425 is interference fitted on the periphery of the first shaft body 4423 to achieve the embracing fixation with the first shaft body 4423, more specifically, the other end of the embracing structure 4425 is provided with a slit 44251, which is extended from the outer edge of the other end of the embracing structure 4425 to the inner wall of the other end of the embracing structure 4425 abutting against the first shaft body 4423, and the slit gap of the slit 44251 extends along the axial direction of the first shaft body 4423. The other end of the embracing structure 4425 utilizes the elastic expansion and contraction characteristics of the slit 44251 to achieve the surrounding embracing of the first shaft body 4423 with different outer diameter sizes, and to expand the tolerance range allowed by the interference fit between the embracing structure 4425 and the first shaft body 4423.

[0114] In the present application, the first shaft body 4423 and / or the second shaft body 4424 are hollow shaft bodies, through which the wires and pipelines can pass, so as to prevent the wires and pipelines from being damaged by external irregular swinging, and to reduce the activity range of the wires and pipelines and prevent the wires from being damaged. Considering that the second shaft body 4424 needs to bear a larger load, preferably, in the present embodiment, the first shaft body 4423 is a hollow shaft body, and the second shaft body 4424 is a solid shaft body, of course, in other embodiments, if the second shaft body 4424 can bear a larger load, the second shaft body 4424 can also be arranged as a hollow shaft body, or the first shaft body 4423 and the second shaft body 4424 are both arranged as hollow shaft bodies.

[0115] It should be noted that considering that the whole tilting mechanism is installed on one side, the longer the protruding distance of the first shaft body 4423 is, the greater the bending moment of the first shaft body 4423 will be, preferably, please refer to Figure 12 In an embodiment, the first shaft body 4423 and the tail wing 30 are provided with a relatively long axial fitting surface 4432, which can increase the installation length of the first shaft body 4423, increase the contact area between the first shaft body 4423 and the tilting drive device seat, balance the bending moment of the first shaft body 4423, and further reduce the bending deformation of the first shaft body 4423, and improve the installation stability of the whole mechanism.

[0116] In an embodiment of the present application, the distance from the rotation center of the tilting driving device 4421 to the axis of the second hinge shaft 4428 is a, the distance from the axis of the first hinge shaft 4427 to the axis of the second hinge shaft 4428 is b, the distance from the center of the first shaft body 4423 to the axis of the first hinge shaft 4427 is c, the distance from the center of the first shaft body 4423 to the center of the second shaft body 4424 is d, a is less than b, c and d respectively, c is greater than b and d respectively, and the sum of a and c is less than the sum of b and d. In this way, once the tilting driving device 4421 loses control, the output shaft of the tilting driving device 4421 is always in a state of forward rotation or reverse rotation, the rocker arm 4422 will swing, that is, the rocker arm 4422 will rotate clockwise to the limit position and then rotate counterclockwise, rotate counterclockwise to the limit position and then rotate clockwise, thus limiting the range of movement of the tilting mechanism, so that the tilting mechanism will not rotate beyond the range and interfere with other components, etc., preventing the front propeller from colliding with the body and other structures due to excessive tilting, and damaging the body and other structures. Therefore, by adjusting the length ratio of each component in the tilting mechanism, the tilting angle range of the tilting mechanism can be constrained, and the limiting problem of the tilting mechanism is cleverly solved, so that the limit position of the forward rotation of the tilting mechanism and the limit position of the reverse rotation are both at the same limit position of the connecting rod. This clever design not only effectively ensures the safety of the mechanism, but also simplifies the design, without the need for additional limiting mechanisms to limit the limit positions, greatly optimizing the installation space of the transmission rod mechanism during movement. Specifically, by adjusting the length ratio of each component in the connecting rod mechanism, the distance between the end axis of the driving arm 4429 (i.e. the axis of the second hinge shaft 4428) and the axis of the first shaft body 4423 is equal in the initial angle state (i.e. the minimum tilting angle) and the final angle state (i.e. the maximum tilting angle), and at this time the angle between the plane formed by the end axis of the driving arm 4429 in the initial angle state and the axis of the first shaft body 4423 and the plane formed by the end axis of the driving arm 4429 in the final angle state and the axis of the first shaft body 4423 is equal to the angle ± 5° of the rotation of the rocker arm 4422, that is, one limiting point can constrain two directions.

[0117] The tilt mechanism in the embodiment has different reduction ratios at different tilt angles, achieves control accuracy requirements at different angles, has compact structure, and reduces space requirements. Through use of the multi-link, the reduction ratio changes with the angle, the reduction ratio can be increased at a large load and reduced at a small load, peak driving torque is reduced, and the demand for driving is reduced. The tilt driving device is a rotary driving structure, and the brake or reduction ratio adjusting device inside the tilt device can amplify the driving force, which can overcome the torque borne by the execution end to achieve state retention at any position, retain the current state position when driving fails, and continue to work after driving is restored, and can make the structural arrangement more concentrated.

[0118] As shown in Figures 1 to 7 , and Figures 20 to 23 , in an embodiment of the vertical take-off and landing aircraft, the rotation axis of the tilt rotor is tilted in the range of -20°-110° with the roll axis X as the reference and the upward direction as the positive direction. Please refer to Figure 21 , 0° is that the rotation axis of the tilt rotor extends forward along the roll axis X; please refer to Figure 23 , 90° is that the rotation axis of the tilt rotor extends upward along the vertical direction, please refer to Figure 22 , the rotation axis of the tilt rotor is in a tilt state between 0° and 90°. It should be noted that when the tilt angle is in the range of 90°-110°, the vertical take-off and landing aircraft can fly forward and backward with the nose, which greatly expands the flight envelope and capability of the vertical take-off and landing aircraft and reduces the risk of needing to turn around in the air. When the vertical take-off and landing aircraft needs to take off, according to flight control needs, the tilt angle of all the tilt rotors on the inside can be set to any angle in the range of 0°-90°, for example, 0°, 30°, 45°, 60°, or 90°.

[0119] The number of tilt rotors on the tail wing 30 can be any even number less than 2N, preferably, please refer to Figures 5 to 9In the embodiment, the VTOL aircraft includes four tilt rotors and four fixed rotors, the four fixed rotors are symmetrically installed on two sides of the fuselage 10, the four tilt rotors are located on the inboard side of the four fixed rotors in the spanwise direction, and two tilt rotors are installed on the tail 30, and two tilt rotors are installed on the fuselage 10 or the wing 20 in front of the wing 20. Specifically, the four tilt rotors are divided into two equal groups, respectively marked as the first group of tilt rotors and the second group of tilt rotors, the first group of tilt rotors is installed on the fuselage 10 or the wing 20 in front of the center of gravity G of the VTOL aircraft, and the second group of tilt rotors is installed on the tail 30 behind the center of gravity G of the VTOL aircraft. The first group of tilt rotors includes a first tilt rotor 41 and a second tilt rotor 42, and the second group of tilt rotors includes a third tilt rotor 43 and a fourth tilt rotor 44. The first tilt rotor 41 is installed on the third arm 411, and the second tilt rotor 42 is installed on the fourth arm 421 and is symmetric about the symmetry plane 60 of the fuselage 10 with the first tilt rotor 41. The third tilt rotor 43 is installed on the tail 30 through a first power pod 442, and the fourth tilt rotor 44 is installed on the tail 30 through a second power pod 442. The first power pod 442 and the second power pod 442 are symmetrically arranged about the symmetry plane 60 of the fuselage 10, and the fourth tilt rotor 44 and the third tilt rotor 43 are symmetrically arranged about the symmetry plane 60 of the fuselage 10.

[0120] In the vertical take-off state, the rotation shafts of the four tilt rotors are all tilted upward in the vertical direction, and the first tilt rotor 41, the second tilt rotor 42, the third tilt rotor 43 and the fourth tilt rotor 44 are all distributed on a first circle with B point as the center. The projections of the first tilt rotor 41 and the fourth tilt rotor 44 on the horizontal plane are centrally symmetric about the B point, and the projections of the second tilt rotor 42 and the third tilt rotor 43 on the horizontal plane are centrally symmetric about the B point.

[0121] Please refer to Figure 7, four fixed rotors are divided into two groups of equal number, and are marked as a first group of fixed rotors and a second group of fixed rotors, the first group of fixed rotors is installed on the wing 20 in front of the center of gravity of the vertical take-off and landing aircraft, and the second group of fixed rotors is installed on the wing 20 behind the center of gravity of the vertical take-off and landing aircraft. The first group of fixed rotors includes a first fixed rotor 51 and a second fixed rotor 52, and the second group of fixed rotors includes a third fixed rotor 53 and a fourth fixed rotor 54, the first fixed rotor 51, the second fixed rotor 52, the third fixed rotor 53 and the fourth fixed rotor 54 are all distributed on a second circle with the point A as the center. The first fixed rotor 51 and the second fixed rotor 52 are symmetrical about the symmetry plane 60 of the fuselage 10, the third fixed rotor 53 and the fourth fixed rotor 54 are also symmetrical about the symmetry plane 60 of the fuselage 10, the rotating shafts of the four fixed rotors all extend upwards, the projections of the first fixed rotor 51 and the fourth fixed rotor 54 on the horizontal plane are centrally symmetrical about the point A, and the projections of the second fixed rotor 52 and the third fixed rotor 53 on the horizontal plane are centrally symmetrical about the point A. It should be noted that, in the present application, the front side refers to the extending direction towards the nose, and the rear side refers to the extending direction towards the tail 30.

[0122] In an embodiment of the vertical take-off and landing aircraft, the distance between the four fixed rotors along the extending direction of the fuselage, that is, the distance between the second fixed rotor 52 and the fourth fixed rotor 54, or the distance between the first fixed rotor 51 and the third fixed rotor 53, is L3. The distance between the four tilting rotors along the extending direction of the fuselage, that is, the distance between the second tilting rotor 42 and the fourth tilting rotor 44, or the distance between the first tilting rotor 41 and the third tilting rotor 43, is L4, and then 0.1(L3+L4)≥4L1+2L2≥0.01(L3+L4). In this way, in the tilting stage and the cruising stage, the center of gravity G is close to the front side relative to the points A and B, and the point B is always located on the side of the point A close to the tail 30, so that the longitudinal and heading static stability margins are relatively large, the aircraft has stronger resistance to extreme wind weather, and the flight is safer.

[0123] Please refer to Figure 7 , the wing 20 on one side of the fuselage 10 is provided with a first arm 511, and the wing 20 on the other side of the fuselage 10 is provided with a second arm 521; the first arm 511 and the second arm 521 are symmetrically arranged about the symmetry plane 60 of the fuselage 10, and 2M fixed rotors are symmetrically installed on the first arm 511 and the second arm 521 on both sides of the fuselage 10 and located on the front and rear sides of the wing 20 and the front and rear ends of the first arm 511 and the second arm 521, and the projections of all the fixed rotors on the horizontal plane are approximately centrally symmetrical about the point A in pairs.

[0124] Please refer to Figures 1 to 4In one embodiment, the VTOL aircraft differs from that in Figures 5 to 9 , in that the VTOL aircraft comprises only four tilt rotors instead of fixed rotors, and the four tilt rotors are symmetrically mounted on both sides of the fuselage 10, wherein two of the tilt rotors are symmetrically mounted on the wings 20 with respect to the fuselage 10, and the structure and corresponding mounting relationship of the four tilt rotors with respect to the fuselage are the same as in Figures 5 to 9 , and Figure 34 , and the specific positions are adjusted according to the aircraft, which will not be described here.

[0125] The VTOL aircraft differs from that in Figures 1 to 4 , in that the VTOL aircraft comprises six tilt rotors instead of fixed rotors, and the six tilt rotors are symmetrically mounted on both sides of the fuselage 10, wherein four of the tilt rotors are symmetrically mounted on the wings 20 with respect to the fuselage 10, and the other two tilt rotors are symmetrically mounted on the tail 30. The tail 30 is a V-tail, and the two tilt rotors on the V-tail are full-tilt rotors, and the two full-tilt rotors are respectively mounted on the wing tips on both sides of the upper part of the V-tail. The two tilt rotors on the wing tips of the wings 20 on both sides of the fuselage 10 are symmetric with respect to the symmetry plane 60 of the fuselage 10, and the tilt rotors on the wing tips of the wings 20 are preferably full-tilt rotors. The last two tilt rotors are mounted on the front side of the wings 20 through the arms and are partial-tilt rotors. However, if conditions permit, the tilt rotors mounted on the front side of the wings 20 through the arms can also be full-tilt rotors.

[0126] In the present application, the mounting position and structure of the elevator 31 can be various, for example, it can be arranged at any suitable position of the tail 30, or it can be any suitable elevator 31 structure. Specifically, please refer to Figure 5 and Figure 17 , the elevator 31 comprises an elevator plate 311 and an elevator body driving device (not shown), the elevator plate 311 is rotationally connected to the tail of the tail 30 or the fuselage 10, and the elevator body driving device drives the rotation of the elevator plate 311 to adjust the direction of the VTOL aircraft. The elevator 31 driving device includes but is not limited to a motor, or a combination of a motor and a speed reducer.

[0127] Please refer to Figure 25 , in some embodiments, the chord length ratio of the elevator plate 311 to the chord length of the tail 30 is 15% to 100%, for example, it can be 15%, 30%, 45%, 60%, 90%, 100%, etc. Any value between 15% and 100%, as an example, as shown in Figure 18As shown, the chord length of the rudder plate 311 accounts for 30% of the chord length of the tail fin 30; as shown in Figure 19 As shown, the chord length of the rudder plate 311 accounts for 60% of the chord length of the tail fin 30; as shown in Figure 20 As shown, the chord length of the rudder plate 311 accounts for 100% of the chord length of the tail fin 30, but not limited to Figures 18 to 20 As shown, the chord length of the rudder plate 311 accounts for 100% of the chord length of the tail fin 30, but not limited to Figure 25 As shown, the chord length of the rudder plate 311 accounts for 100% of the chord length of the tail fin 30, but not limited to

[0128] As shown, the chord length of the rudder plate 311 accounts for 100% of the chord length of the tail fin 30, but not limited to Figure 18 In one embodiment of the VTOL aircraft of the present application, the deflection angle of the rudder plate 311 is -90° to 30°, with the roll axis X as the reference, and the upward direction as the positive direction, as shown in Figure 23 As shown, the deflection angle of the rudder plate 311 can be -90°, -60°, -30°, -15°, 0°, 15°, and 30°, or any angle between -90° and 30°.

[0129] In one embodiment of the VTOL aircraft of the present application, the deflection angle of the rudder plate 311 is -90° to 30°, with the roll axis X as the reference, and the upward direction as the positive direction, as shown in Figure 9 In one embodiment of the VTOL aircraft of the present application, the deflection angle of the rudder plate 311 is -90° to 30°, with the roll axis X as the reference, and the upward direction as the positive direction, as shown in

[0130] In one embodiment of the VTOL aircraft of the present application, the deflection angle of the rudder plate 311 is -90° to 30°, with the roll axis X as the reference, and the upward direction as the positive direction, as shown in Figures 1 to 4In the embodiment, the tail wing 30 is a V-shaped tail wing, and two tilting rotors are mounted on the tail wing 30, and the two tilting rotors are respectively mounted on the wing tips on the two sides of the upper part of the tail wing 30. In other embodiments, the tail wing 30 can also be in any shape described above.

[0131] It should be noted that, in the embodiment, when the tilt-rotor aircraft flies forward in the cruising state, the rotation axis of the tilting rotor on the tail wing 30 and the rotation axis of the tilting rotor at other positions can extend along the roll axis X, but in other embodiments, the rotation axis of the tilting rotor on the tail wing 30 and the rotation axis of the tilting rotor at other positions can not extend along the roll axis X, but can be within the vertical plane of the roll axis X, and within the range of ±20° based on the roll axis X. Moreover, in the tilt-rotor aircraft, the control of the power pods 442 of the tilting rotors at different positions along the roll axis X can be independent of each other, and the tilting can also be independently controlled without being associated with each other. In this mode, the tilting angles of the tilting rotors on the front side and the tail wing 30 can be different, and the tilting process can be different. For example, taking the roll axis X as 0°, taking the position above the roll axis X as positive, and taking the position below the roll axis X as negative, the tilting angle of the power pod 442 of the tilting rotor on the front side of the fuselage 10 or the wing 20 can be 10°, and the tilting angle of the power pod 442 of the tilting rotor on the rear side of the fuselage 10 or the wing 20 can be -10°.

[0132] It should be noted that, in the tilt-rotor aircraft, when the tilt-rotor aircraft is in the vertical take-off and landing state, the rotation axis of the tilting rotor on the tail wing 30 and the rotation axis of the tilting rotor at other positions can extend upward along the vertical direction, or can not extend upward along the vertical direction. That is, the tilting angle of the tilting rotor on the front side and the tilting rotor on the tail wing 30 is not limited to 90° tilting angle. In order to enhance the control ability, the tilting angle of the rotation axis of the tilting rotor on the front side and the tilting angle of the rotation axis of the tilting rotor on the tail wing 30 can be any value between 70° and 110°, such as 70°, 80°, 90°, 100° and 110°, etc. The rotation control and the tilting control of each of the 2N tilting rotors are relatively independent, and the tilting angles of the 2N tilting rotors can be completely consistent, or can be different between any two, or can be partially consistent. For example, the tilting angles of the tilting rotors on the fuselage 10 or the wing 20 on the front side of the tail wing 30 among the 2N tilting rotors can be consistent, and marked as a first tilting angle, the tilting angles of the tilting rotors on the tail wing 30 on the rear side can be consistent, and marked as a second tilting angle, and the first tilting angle is not equal to the second tilting angle, for example, the first tilting angle can be 100°, and the second tilting angle can be 80°. In this way, different positions can obtain different pitch trim moments. It should be noted that the tilting angle is the angle between the rotation axis of the tilting rotor and the roll axis X, with the center point of the tilting axis of the tilting rotor as the vertex.

[0133] Referring to Figure 7 and Figures 28 to 32 , the present application provides a control method of a vertical take-off and landing aircraft, wherein the vertical take-off and landing aircraft comprises a fuselage and 2N tilting rotors. The fuselage 10 is a symmetrical structure and has a symmetrical plane 60 extending along the length direction of the fuselage 10. Wings 20 are arranged on both sides of the fuselage 10, and the wings 20 on both sides are symmetrical relative to the symmetrical plane 60 of the fuselage 10. A tail fin 30 is arranged at the tail of the fuselage 10, and an elevator 31 is arranged on the tail fin 30. 2N tilting rotors are installed on both sides of the fuselage 10, N is a natural number greater than or equal to 2, the 2N tilting rotors are symmetrically arranged about the symmetrical plane 60 of the fuselage 10, and a part of the 2N tilting rotors are installed on the tail fin 30. In the vertical take-off and landing state, the projections of the propellers of the 2N tilting rotors on the horizontal plane are centrally symmetric about point B, the point B and the center of gravity G of the vertical take-off and landing aircraft are both located in the symmetrical plane of the fuselage, and the point B is located on the side of the center of gravity G close to the tail fin. During the transition of the vertical take-off and landing aircraft from the vertical take-off and landing state to the cruising state, the center of gravity G and the point B both move along the symmetrical plane to the side close to the nose, and the point B is always located on the side of the center of gravity G close to the tail fin.

[0134] In an embodiment of the vertical take-off and landing aircraft of the present application, the following method is used for pitch control:

[0135] During flight, the pitch control proportion of the elevator 31 and the 2N tilting rotors and the 2M fixed rotors is allocated according to the current airspeed or dynamic pressure; and the elevator 31, the 2N tilting rotors and the 2M fixed rotors are controlled respectively according to the pitch control proportion to realize pitch trim and control.

[0136] In an embodiment of the vertical take-off and landing aircraft of the present application, controlling the 2N tilting rotors according to the pitch control proportion includes: a tilting angle differential adjustment process, that is, the pitch moment is differentially adjusted by the tilting angle difference between the tilting rotor on the tail fin 30 and any other tilting rotor on the front side of the tail fin to realize pitch trim and control; and / or a rotation speed differential adjustment process, that is, the pitch moment is differentially adjusted by the rotation speed difference between the tilting rotor on the tail fin 30 and any other tilting rotor on the front side of the tail fin to realize pitch trim and control; and / or a tilting speed differential adjustment process, that is, the pitch moment is differentially adjusted by the tilting speed difference between the tilting rotor on the tail fin and any other tilting rotor on the front side of the tail fin to realize pitch trim and control. It should be noted that the above-mentioned tilting angle differential adjustment process, rotation speed differential adjustment process and tilting speed differential adjustment process can be implemented independently, can be implemented in pairs, or can be implemented simultaneously.

[0137] Referring to Figure 28 The flight process includes four stages in sequence, specifically including: S100, a ground preparation process, S200, a take-off control process, S300, a take-off to level flight control process, and S400, a cruising state.

[0138] S100, the ground preparation process. The ground preparation process first needs to start the vertical take-off and landing aircraft, and detect the power-on of the system, and then confirm the full stroke state of the servo system such as the tilt mechanism and the elevators 31.

[0139] S200, the take-off control process. The take-off control process is the process of the vertical take-off and landing aircraft climbing from the ground to a set height. In this process, the tilt angle and the rotation speed of the tilt rotor and the fixed rotor are kept unchanged. Compared with the level flight process, this process is relatively stable.

[0140] S300, the take-off to level flight control process. In the take-off to level flight control process, the change of the tilt angle of the tilt rotor and / or the change of the rotation speed of the tilt rotor and / or the fixed rotor are involved. Therefore, the pitch impact force in this process is larger, and the control of the vertical take-off and landing aircraft is relatively difficult.

[0141] S400, the cruising state. In the cruising state, the vertical take-off and landing aircraft is in level flight, and the aircraft navigates along the horizontal direction, which is relatively stable.

[0142] Referring to Figure 32 In an embodiment, the take-off control process of step S200 includes the following steps:

[0143] S211, tilt the 2N tilt rotors to the vertical upward rotation axis to the vertical take-off position or the inclined position (for example, it can be between 0°-90°) to provide power for climbing. The vertical take-off position can be a position where the rotation axis of the tilt rotor and the roll axis form a 90° angle; the inclined position can be a position where the rotation axis of the tilt rotor and the roll axis form an angle between 0°-90° (excluding the end point value);

[0144] S212, deflect the elevators 31 downward, so that the elevators 31 participate in the take-off control;

[0145] S213, start the 2N tilt rotors, and issue a level flight instruction when the vertical take-off and landing aircraft reaches a set height.

[0146] In the take-off process of S211 to S213, if the tilt-rotor is set to 90°, the VTOL aircraft takes off normally vertically, and the oil of the 2N tilt-rotors can be opened to the same level. At this time, the tilt-rotors on the tail 30 have the largest blocking area in the vertical take-off stage and the transition stage, which will cause a larger lifting moment. If the rotation axis of all tilt-rotors is set to an inclined position between 0° and 90°, when the aircraft takes off, the inner tilt-rotors are started to open the oil. Since the inner tilt-rotors provide a forward pulling force component, at this time the aircraft climbs obliquely upward, and when the flight speed gradually increases, the tilt angle of the inner tilt-rotors gradually decreases until the tilt is set to 0° to convert to the fixed-wing mode. In this scheme, the lifting moment caused by the tail 30 blocking the tilt-rotor of the aircraft is moderate, the control difficulty is smaller, and the maximum pulling force margin requirement of the power system is smaller.

[0147] As an optimization, please refer to Figure 29 In this embodiment, the take-off and flat flight control process in S300 includes the following processes:

[0148] S310, responding to the flat flight instruction. The flat flight instruction can be issued by the pilot or can be issued by the VTOL aircraft when it is determined that the preset flight condition is met.

[0149] S320, rotor control process. This process is greatly affected by the take-off control process in S200, and there will be great differences according to the state of the tilt-rotor.

[0150] S330, pitch control process. Considering that in the take-off and flat flight process, the tilt-rotor is tilted to the set cruise position many times, in which the rotation axis of the tilt-rotor is parallel to the roll axis, and the VTOL aircraft will be subjected to a certain pitch impact force during each tilt process, the pitch control process S330 can be performed after each S320 rotor control process in the take-off and flat flight.

[0151] S340, sequentially repeating the rotor control process and the pitch control process until the tilt-rotor is tilted to the cruise position, and the take-off and flat flight is completed. The cruise position may, for example, be a position where the tilt angle is 0° and the rotation axis of the tilt-rotor is parallel to the roll axis.

[0152] Please refer to Figure 31 In an embodiment, the rotor control process S320 includes the following steps:

[0153] S321, obtaining the current tilt position of each tilt-rotor; this process can set an angle sensor on the tilt-rotor to feed back the current tilt position to the central control system, or the corresponding tilt driving device of the tilt-rotor can directly feed back the corresponding current tilt position to the central control system.

[0154] S322, if the current tilt position is inconsistent with the set cruise position, the current airspeed or dynamic pressure of the corresponding tilt rotor at the current tilt position is obtained, and it is determined whether the current airspeed or dynamic pressure is equal to or greater than a preset threshold at the current tilt position; it should be noted that the set cruise position is a position where the preset vertical take-off and landing aircraft is in a level flight state, for example, it can be a 0° position where the rotation axis of the tilt rotor is parallel to the roll axis X, or it can be another position between 0°±5°.

[0155] S323, if the current airspeed or dynamic pressure is equal to or greater than the preset threshold at the current tilt position, the tilt rotor is controlled to tilt to a preset next position;

[0156] S324, gradually increase the speed of the 2N tilt rotors. If, as shown in Figure 1 , the vertical take-off and landing aircraft does not have 2M fixed rotors, the forward power can be obtained by gradually increasing the speed of the 2N tilt rotors. But if, as shown in Figure 7 , the vertical take-off and landing aircraft has 2N tilt rotors and 2M fixed rotors, in order to realize level flight, the speed of the 2M fixed rotors also needs to be gradually reduced to a set speed while the speed of the 2N tilt rotors is gradually increased.

[0157] Please refer to Figure 7 , in another embodiment, the vertical take-off and landing aircraft includes 2M fixed rotors, M is a natural number greater than or equal to 2, M can have the same value as N or a different value. The 2M fixed rotors are symmetrically installed on the wings on both sides of the fuselage and located outside the tilt rotors; in the vertical take-off and landing state, the projections of all the fixed rotors on the horizontal plane are centrally symmetric about point A, the A point is located in the symmetry plane of the fuselage, and coincides with the G point or is located on the side of the G point close to the tail. During the transition of the vertical take-off and landing aircraft from the vertical take-off and landing state to the cruise state, the G point and the B point move along the symmetry plane to the side close to the nose, and the G point is located on the side close to the nose of the A point or coincides with the A point, and the B point is always located on the side close to the tail of the A point. Please refer to Figure 33 , in an embodiment, the take-off process of the vertical take-off and landing aircraft in S200 is different from the process in S211 to S213 in Figure 32 , the take-off process of S200 includes:

[0158] S221, tilt the 2N tilt rotors to the rotation axis horizontal forward, parallel to the roll axis X;

[0159] S222, deflect the elevator 31 downward;

[0160] S223, start 2M fixed rotors and 2N tilting rotors, and when the VTOL aircraft reaches the set height, issue the level flight instruction.

[0161] In the take-off process in S221 to S223, the rotation axis of all tilting rotors is set to 0° (as shown in Figure 7 ), the aircraft becomes a compound wing mode, the aircraft is vertically taken off by the outer rotors, the output of the outer rotors at this time is twice that of the control scheme one, and the inner tilting rotors are gradually started in the vertical to level flight transition stage, and the throttle is gradually increased until the level flight is successful. This scheme has the smallest tail wing 30 blocking area of the inner tilting rotors, the smallest lifting moment, and the simplest control, which is basically the control mode of the compound wing, but the required power system tension margin is larger, and the requirement for the power system is higher. Reduce this control mode in non-emergency situations.

[0162] As can be understood by those skilled in the art, since the axis of the tilting rotor is always parallel to the roll axis X in the take-off process in S221 to S223, in the rotor control process in S320 in the take-off to level flight control process in S300, the related processes in S321 to S323 are no longer needed, and only the rotation speed of the 2N tilting rotors needs to be gradually increased, and the rotation speed of the 2M fixed rotors needs to be gradually reduced to the set rotation speed.

[0163] It should be noted that whether the rotor control process in S300 has the tilting control process in S321 to S324, the VTOL aircraft will be subjected to a high pitch impact force during the take-off to level flight process. Based on this, please refer to Figure 30 , in an embodiment of the application, the pitch control process in step S330 includes:

[0164] S332, according to the current airspeed or dynamic pressure, the pitch control proportion of the elevators 31, the 2N tilting rotors and the 2M fixed rotors is distributed. In this process, according to the current speed of the VTOL aircraft, the pitch adjustment force is distributed to the elevators 31, the 2N tilting rotors and the 2M fixed rotors according to the set distribution rule, so as to achieve more balanced pitch control through the pitch control proportion.

[0165] S333, according to the pitch control proportion, the elevators, the 2N tilting rotors and the 2M fixed rotors are controlled respectively to realize pitch balance and control. In this process, the central control system controls the elevators 31, the 2N tilting rotors and the 2M fixed rotors respectively according to the distributed pitch control proportion, for example, differential speed control, deflection of the elevators 31, etc., so that different pitch adjustment forces are generated at different positions of the VTOL aircraft, so as to balance the pitch impact force in the level flight process.

[0166] In an embodiment, the vertical take-off and landing aircraft of the present application is provided with 2N tilting rotors inside 2M fixed rotors, and is provided with elevators 31 and fully tilting tilting rotors on tail 30, so that the pitch impact force during tilting flight can be balanced through the above pitch control process, on the one hand, a more stable control process can be obtained. On the other hand, in the pitch control process, the power pod 442 of the tilting rotor on the tail 30 rotates with the rotor during tilting, and the power pod 442 is immersed in the rotor with a small blocking area during hovering, so the area of the rotor wash flow hitting the tail 30 is smaller, which can reduce a part of the lifting moment, and can improve the control of the vertical take-off and landing aircraft in complex interference flow field.

[0167] It should be noted that if the vertical take-off and landing aircraft does not include 2M fixed rotors, in step S332, the fixed rotors do not need to be considered, and only the pitch control proportion of the elevators 31 and the 2N tilting rotors according to the current airspeed or dynamic pressure is allocated. And correspondingly, in step S333, the fixed rotors also do not need to be considered, and only the elevators 31 and the 2N tilting rotors are controlled according to the pitch control proportion to realize pitch balancing and steering.

[0168] It should be noted that the elevators 31 are often involved in the control process during the take-off of the vertical take-off and landing aircraft, so in the above pitch control process of the present application, before step S332, it also includes: step S331, controlling the elevators 31 to return to zero or actuate to a trim rudder deflection value matched with the current air / dynamic pressure in time according to the current airspeed or dynamic pressure, and gradually participating in the pitch control process. For example, an airspeed threshold can be set, when the current airspeed is greater than or equal to the set airspeed threshold, the elevators 31 are returned to zero, back to the initial position without deflection, and the rudder deflection angle is 0° at this time.

[0169] In the embodiment, controlling the elevators 31 and the 2N tilting rotors according to the pitch control proportion to realize pitch balancing and steering includes: differentiating the tilting speed difference and / or the tilting angle difference between the tilting rotors at different positions and / or the rotation speed difference of the tilting rotors to adjust the pitch moment to realize pitch balancing and steering.

[0170] Please refer to Figure 27 , Figure 27 To generate the whole machine pitch moment curve of the partial tilting scheme of the power pod of the tilting rotor on the tail 30 and the full tilting scheme of the power pod of the tilting rotor on the tail 30 through aerodynamic simulation analysis. The first curve 101 is the simulation curve of the simulation model in Figure 7 , the tilting rotor structure of the tail in the aerodynamic simulation analysis refers to Figure 20, the second curve 102 is a partial tilt model, the partial tilt model is different from the full tilt model in that the partial tilt model only tilts the rotors on the tail 30, and the rest is the same as the full tilt scheme. In the simulation analysis of the two models, the rotational speeds of the four fixed rotors and the four tilt rotors are equal, and the pulling forces match the takeoff weight of the aircraft (the pulling force is in a state of force balance with gravity). Figure 7

[0171] Figure 27 In the first curve 101 and the second curve 102, the full machine pitch moment of the two models changes with the flight speed (i.e. the wind speed), the flight speed in the figure is dimensionless, the process of 0-1 is that the aircraft flies from the hover state to the maximum speed at the current tilt angle (the above-mentioned 90° tilt angle is kept unchanged), that is, from the minimum speed to the maximum speed at the current tilt angle; the pitch moment in the figure is also dimensionless.

[0172] From the comparison between the first curve 101 and the second curve 102, it can be seen that, in the case that the eight rotors have no front-rear oil differential, the aircraft will generate a large pitch moment, so in order to realize the stable flight of the aircraft, the pitch moment needs to be balanced, so that the pitch direction angular acceleration is 0, then in order to balance this part of the aerodynamic pitch moment, the front-rear rotor oil differential needs to be generated to offset the pitch moment generated by the rotor differential and the aerodynamic pitch moment generated by the aircraft body. The maximum pitch balancing and control required by the full tilt scheme of the power pod 442 in the flight process is 0.25 units. The maximum pitch balancing and control required by the partial tilt scheme of the power pod 442 in the flight process is 0.8 units, which is much greater than the full tilt control method, the greater the pitch moment generated in the flight process, the more difficult the aircraft is to control, and the greater the additional power required by the power system to adjust the attitude of the aircraft. In addition, it can also be seen from the simulation curve shown in Figure 27 Figure 27 As the flight speed increases, the fluctuation of the pitch balancing and control required by the partial tilt scheme of the power pod 442 is also large, from -0.04 at the hover state (dimensionless wind speed is 0) to about 0.8 at the dimensionless wind speed of 0.57, the pitch moment fluctuation is very large, which is extremely unfavorable for the pitch control of the aircraft; on the contrary, the pitch moment generated by the full tilt scheme of the power pod 442 changes from -0.25 at the hover state (dimensionless wind speed is 0) to about 0.25 at the dimensionless wind speed of 0.42, the pitch moment fluctuation is small, which is conducive to the control of the pitch direction of the aircraft, therefore, the vertical take-off and landing aircraft and the pitch control method provided by the present application are simple and effective, and can effectively improve the safety of the aircraft.

[0173] ​​In summary, the vertical take-off and landing aircraft is provided with elevators and 2N tilt rotors. In the vertical take-off and landing state, the projections of the 2N tilt rotors on the horizontal plane are centrally symmetric about the point B, the point B and the center of gravity G of the vertical take-off and landing aircraft are located on the symmetry plane of the fuselage, and the point B is located on the side of the point G close to the tail. During the transition of the vertical take-off and landing aircraft from the vertical take-off and landing state to the cruising state, the point B is always located on the side of the point G close to the tail. With this layout, the center of gravity G of the vertical take-off and landing aircraft and the symmetry center B of the tilt rotors are not coincident, and during the transition of the vertical take-off and landing aircraft from the vertical take-off and landing state to the cruising state, the points G and B are both moved along the symmetry plane to the side close to the nose. Therefore, the pulling force of the front tilt rotors on the center of gravity G has a smaller moment, the pulling force of the rear tilt rotors on the center of gravity G has a larger moment, and the moment difference of the front and rear tilt rotors can resist the part of the lifting moment of the tail caused by the washout area of the tilt rotors on the tail, thereby reducing the difficulty of pitch control. Therefore, under the condition that the tilt rotors on the front and rear sides of the center of gravity G have the same speed and throttle, a lowering moment can be generated due to the difference in the length of the force arm on the center of gravity G, which can offset or partially offset the lifting moment of the tail caused by the washout area of the tilt rotors on the tail, thereby enabling the vertical take-off and landing aircraft to be well trimmed in the pitch moment under the condition that the front and rear tilt rotors have the same throttle.

[0174] The control method of the present application allocates the pitch control proportion of the elevators and the 2N tilt rotors according to the current airspeed or dynamic pressure, and can realize pitch control through the linkage of the elevators and the 2N tilt rotors. Therefore, the present application effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

Claims

1. A vertical take-off and landing aircraft characterised in that, The vertical take-off and landing aircraft comprises: a fuselage, two sides of the fuselage are provided with wings, the tail of the fuselage is provided with a tail wing, and the tail wing is provided with an elevating rudder; 2N tilting rotors are symmetrically installed on both sides of the fuselage, and a part of the 2N tilting rotors are located on the tail wing; wherein N is a natural number greater than or equal to 2, in the vertical take-off and landing state, the projections of the 2N tilting rotors on the horizontal plane are centrally symmetric about point B, the point B and the gravity center G of the vertical take-off and landing aircraft are located in the symmetry plane of the fuselage, and the point B is located on the side of the gravity center G close to the tail wing, during the mode change of the vertical take-off and landing aircraft, the gravity center G and the point B move along the symmetry plane, and the point B is always located on the side of the gravity center G close to the tail wing; the tail wing is a V-tail wing, two tilting rotors are installed on the V-tail wing, and the two tilting rotors are respectively installed at the wing tips of the V-tail wing, in the vertical take-off and landing state, the distance between the rotation center of the tilting rotor on the tail wing and the leading edge of the wing tip of the V-tail wing is t1, and the chord length of the wing tip of the V-tail wing is t2, wherein the ratio of t1 to t2 is 15% to 40%.

2. The vertical take-off and landing aircraft according to claim 1, wherein during flight, the rotation axis of any tilting rotor on the tail wing and the rotation axis of any other tilting rotor at another position have projections on the symmetry plane of the fuselage that are not parallel; in the cruising state and / or the vertical take-off state and / or the mode conversion state, the tilting speed of any tilting rotor on the tail wing and the tilting speed of any other tilting rotor at another position have a first difference, and the first difference is not equal to 0.

3. The vertical take-off and landing aircraft according to claim 1, wherein during flight, the rotation axis of any tilting rotor on the tail wing and the rotation axis of any other tilting rotor at another position have projections on the symmetry plane of the fuselage that are not parallel; in the cruising state and / or the vertical take-off state and / or the mode conversion state, the rotation speed of any tilting rotor on the tail wing and the rotation speed of any other tilting rotor at another position have a second difference, and the second difference is not equal to 0.

4. The vertical takeoff and landing aircraft of claim 1, wherein, The vertical take-off and landing aircraft adopts the following method for pitch control: during flight, the pitch control proportion of the elevating rudder and the 2N tilting rotors is allocated according to the current airspeed or dynamic pressure; the elevating rudder and the 2N tilting rotors are controlled respectively according to the pitch control proportion to realize pitch trim and control; wherein the control of the 2N tilting rotors according to the pitch control proportion comprises: the tilting angle difference between the tilting rotor on the tail wing and any other tilting rotor is used to differentially adjust the pitch moment to realize pitch trim and control; and / or, the rotation speed difference between the tilting rotor on the tail wing and any other tilting rotor is used to differentially adjust the pitch moment to realize pitch trim and control; And / or, the difference in tilt speed between the tilt rotor on the tail and any other tilt rotor differentially adjusts the pitch moment for pitch trim and control.

5. The vertical take-off and landing aircraft according to claim 2, wherein, The vertical take-off and landing aircraft comprises four tilt rotors, two of which are symmetrically mounted on the wings about the fuselage, and the other two are symmetrically mounted on the tail about the fuselage.

6. The vertical take-off and landing aircraft according to claim 2, wherein, The vertical take-off and landing aircraft comprises six tilt rotors, four of which are symmetrically mounted on the wings about the fuselage, and the other two are symmetrically mounted on the tail about the fuselage.

7. The vertical take-off and landing aircraft of claim 5 or 6, wherein, The two tilt rotors on the tail are full tilt rotors; and / or, wherein two tilt rotors are provided on the wingtips, and the tilt rotors on the wingtips are full tilt rotors.

8. The vertical takeoff and landing aircraft of claim 1, wherein, The vertical take-off and landing aircraft further comprises 2M fixed rotors, M being a natural number greater than or equal to 2, and 2M fixed rotors are symmetrically mounted on the wings on both sides of the fuselage and outside the tilt rotors; in the vertical take-off and landing state, the projections of all the fixed rotors on the horizontal plane are centrally symmetric about point A, which is located in the symmetry plane of the fuselage, and during the mode change of the vertical take-off and landing aircraft, point G is located on the side of point A close to the nose or coincides with point A, and point B is always located on the side of point A close to the tail.

9. The vertical take-off and landing aircraft of claim 8, wherein, The vertical take-off and landing aircraft uses the following method for pitch control: During flight, the pitch control proportion of the elevators, 2N tilt rotors and 2M fixed rotors is allocated according to the current airspeed or dynamic pressure; According to the pitch control proportion, the elevators, 2N tilt rotors and 2M fixed rotors are controlled respectively to achieve pitch trim and control.

10. The vertical take-off and landing aircraft according to claim 8, wherein, The vertical take-off and landing aircraft comprises four tilt rotors and four fixed rotors, four fixed rotors are symmetrically mounted on both sides of the fuselage, four tilt rotors are located inside the four fixed rotors, and two of the tilt rotors are symmetrically mounted on the tail, and the two tilt rotors on the tail are full tilt rotors.

11. The vertical take-off and landing aircraft according to claim 1, wherein, The tilt rotors on the tail are full tilt rotors; the tilt rotors outside the tail are partial tilt rotors; or Tilt rotors are provided on the wingtips of the wings, and the tilt rotors on the tail and the tilt rotors on the wingtips of the wings are full tilt rotors.

12. The vertical take-off and landing aircraft according to claim 11, wherein, The fully tilting rotor includes a first rotor and a power pod. The first rotor is connected to the power pod, and the power pod is rotatably connected to the tail or the wing. The power pod tilts synchronously with the first rotor during the tilting process.

13. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The elevator rudder includes a rudder plate and a rudder drive device. The rudder plate is rotatably connected to the tail fin or the tail of the fuselage. The rudder drive device drives the rudder plate to rotate in order to adjust the direction of the vertical take-off and landing aircraft.

14. The vertical takeoff and landing aircraft according to claim 13, characterized in that, With the roll axis X as the reference and upward as the positive direction, the deflection angle of the rudder plate is -90° to 30°; And / or, the ratio of the chord length of the rudder to the chord length of the tail fin is 15% to 100%.

15. The vertical takeoff and landing aircraft according to claim 1, characterized in that, With the roll axis X as the reference and upward as the positive direction, the rotation axis of the tilting rotor tilts within the range of -20° to 110°; And / or, the angle α between the plane formed by the axis of rotation of the tilt rotor during the tilting process and the plane of symmetry of the fuselage is -15° to +15°.

16. A control method for the vertical take-off and landing aircraft of claim 1, characterized by, This includes the following pitch control procedures: The pitch control ratio of the elevator rudder and the 2N tilt rotors is allocated according to the current airspeed or dynamic pressure. According to the pitch control ratio, the elevator rudder and the 2N tilt rotors are controlled respectively to achieve pitch trim and maneuvering.

17. The control method according to claim 16, characterized by, Before allocating the pitch control ratio of the elevator rudder to the 2N tilt rotors based on the current airspeed or dynamic pressure, the following rotor control process is also included: Obtain the current tilt position of each tilt rotor; If the current tilt position is inconsistent with the set cruise position, the current airspeed or dynamic pressure of the corresponding tilt rotor at the current tilt position is obtained, and it is determined whether the current airspeed or dynamic pressure is equal to or greater than the preset threshold at the current tilt position. If the current airspeed or dynamic pressure is equal to or greater than the preset threshold at the current tilt position, then control the tilt rotor to tilt to the next preset position; Gradually increase the rotational speed of the 2N tilt rotors.

18. The control method according to claim 17, characterized by, The control method further includes: sequentially repeating the rotor control process and pitch control process until the tilt rotor tilts to the cruise position, completing the takeoff to level flight.

19. The control method according to claim 17, characterized in that, The vertical takeoff and landing aircraft also includes 2M fixed rotors, where M is a natural number greater than or equal to 2; Two M fixed rotors are symmetrically mounted on the wings on both sides of the fuselage and located outside the tilt rotor; The process of gradually increasing the rotational speed of the 2N tilt rotors also includes gradually decreasing the rotational speed of the 2M fixed rotors to the set speed.

20. The control method according to claim 19, wherein The following takeoff control process is included before the rotor control: Tilt the 2N tilt rotors so that the axis of rotation is vertically upward or tilted upward; Deflect the elevator rudder downwards; Activate 2M fixed rotors and 2N tilt rotors, and once the vertical takeoff and landing aircraft reaches the set altitude, issue a level flight command.

21. The control method of claim 16, wherein, the VTOL aircraft further comprises 2M fixed rotors, M is a natural number greater than or equal to 2; 2M fixed rotors are symmetrically installed on the wings on both sides of the fuselage and are located outside the tilt rotors; before the pitch control proportion of the elevators and 2N tilt rotors is allocated according to the current airspeed or dynamic pressure, the following take-off control process is further included: tilt 2N tilt rotors to the horizontal forward rotation axis; deflect the elevators downward; start 2M fixed rotors and 2N tilt rotors, and when the VTOL aircraft reaches the set height, issue a level flight command.

22. The control method according to claim 21, wherein After the take-off control process, before the pitch control, the following rotor control process is further included: gradually increase the speed of 2N tilt rotors, issue a forward flight command and gradually reduce the speed of 2M fixed rotors to a set speed.

23. The control method according to claim 20 or 22, characterized by, In the rotor control process, after gradually reducing the speed of 2M fixed rotors to a set speed, the following control is further included: control the elevators to return to zero according to the current airspeed or dynamic pressure, and gradually participate in the pitch control process.

24. The control method according to claim 20 or 22, characterized by, Before the take-off control process, a ground preparation process is further included, which comprises: starting the VTOL aircraft, detecting the power-on of the system, and confirming the full stroke state of the servo system.

25. The control method according to any one of claims 16 to 22, characterized by, According to the pitch control proportion, the elevators and 2N tilt rotors are controlled respectively to realize pitch trim and control, which comprises: differential adjusting the pitch moment through the difference in tilt speed and / or tilt angle and / or rotation speed between the tilt rotors at different positions to realize pitch trim and control.

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