Vertical take-off and landing aircraft and method of controlling the same

Abstract

The application 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 both sides of the fuselage, a tail is arranged at the tail of the fuselage, and an elevator is arranged on the tail. The 2N tilting rotors are symmetrically arranged on both sides of the fuselage, and part of the 2N tilting rotors are arranged 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 tilting rotors on the horizontal plane are centrally symmetric about point B. 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 point B is located on the side of the center of gravity G close to the tail. In the process of 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 point B move along the symmetry plane to the side close to the nose, and point B is always located on the side of the center of gravity G close to the tail. The layout can make the vertical take-off and landing aircraft have good trim and pitch ability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft technology, in particular to a vertical take-off and landing aircraft and a control method thereof. BACKGROUND

[0002] The vertical take-off and landing fixed-wing aircraft (distributed propulsion) has both the vertical take-off and landing capability of the helicopter and the horizontal high efficiency and high speed flight capability of the fixed-wing aircraft, and is more quiet, comfortable and economical than the helicopter, more efficient and longer in range than the multi-rotor, and can vertically take off and land on the 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

[0003] 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 the pitch control is not easy.

[0004] 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. 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 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 propellers 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. In the process of 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.

[0005] 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 which are not parallel.

[0006] In an embodiment of the vertical take-off and landing aircraft of the present application, 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 and the tilting speed of any tilting rotor at other positions have a first difference, and the first difference is not equal to 0.

[0007] 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 tilting rotors on the tail and the rotation speed of any of the other tilting rotors, and the second difference is not equal to 0, in the cruising state and / or the vertical take-off state and / or the modal transition state.

[0008] 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:

[0009] During flight, the elevator and the pitch control proportion of the 2N tilting rotors are distributed according to the current airspeed or dynamic pressure;

[0010] According to the pitch control proportion, the elevator and the 2N tilting rotors are controlled respectively to achieve pitch trim and control.

[0011] 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:

[0012] The pitch moment is differentially adjusted by the difference in tilt angle between the tilting rotors on the tail and any of the other tilting rotors to achieve pitch trim and control;

[0013] And / or, the pitch moment is differentially adjusted by the difference in rotation speed between the tilting rotors on the tail and any of the other tilting rotors to achieve pitch trim and control;

[0014] And / or, the pitch moment is differentially adjusted by the difference in tilt speed between the tilting rotors on the tail and any of the other tilting rotors to achieve pitch trim and control.

[0015] In an embodiment of the vertical take-off and landing aircraft of the present application, the vertical take-off and landing aircraft includes four tilting rotors, two of which are symmetrically mounted on the wings about the fuselage, and the other two are symmetrically mounted on the tail.

[0016] In an embodiment of the vertical take-off and landing aircraft of the present application, the vertical take-off and landing aircraft includes six tilting rotors, four 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 tail is a V-tail, and the two tilting rotors on the tail are full-tilt rotors, each mounted on the wingtip of the upper part of the V-tail.

[0018] In an embodiment of the vertical take-off and landing aircraft of the present application, two of the tilt rotors are located at the wing tips of the wings, and the tilt rotors located at the wing tips of the wings are full tilt rotors.

[0019] In an embodiment of the vertical take-off and landing aircraft of the present application, 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 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 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.

[0020] In an embodiment of the vertical take-off and landing aircraft of the present application, the vertical take-off and landing aircraft is controlled in pitch by the following method:

[0021] In the process of 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;

[0022] According to the pitch control proportion, the elevators, 2N tilt rotors and 2M fixed rotors are controlled respectively to realize pitch trim and control.

[0023] In an embodiment of the vertical take-off and landing aircraft of the present application, four fixed rotors are symmetrically installed on both sides of the fuselage, four tilt rotors are located inside the four fixed rotors, and two of the tilt rotors are symmetrically installed on the tail, and the tilt rotors located on the tail are full tilt rotors.

[0024] In an embodiment of the vertical take-off and landing aircraft of the present application, the tail is a V-tail, two tilt rotors are installed on the V-tail, and the two tilt rotors are respectively installed at the wing tips of the V-tail; in the vertical take-off and landing state, the distance between the rotation center of the tilt rotor 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%.

[0025] In an embodiment of the vertical take-off and landing aircraft of the present application, the tilt rotors located on the tail are full tilt rotors; the tilt rotors located outside the tail are partial tilt rotors.

[0026] In an embodiment of the vertical take-off and landing aircraft, the wing tip of the wing is provided with a tilting rotor, and the tilting rotor on the tail and the tilting rotor on the wing tip are all full-tilting rotors.

[0027] In an embodiment of the vertical take-off and landing aircraft, the full-tilting 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 tilts synchronously with the first rotor during tilting of the first rotor.

[0028] 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 elevator plate to rotate to adjust the direction of the vertical take-off and landing aircraft.

[0029] 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 tilting rotors. The fuselage is provided with wings on both sides, a tail on the tail of the fuselage, and an elevator on the tail. The 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. 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 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 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:

[0030] According to the current airspeed or dynamic pressure, the pitch control proportion of the elevator and the 2N tilting rotors is allocated.

[0031] According to the pitch control proportion, the elevator and the 2N tilting rotors are controlled respectively to realize pitch trim and control.

[0032] In an embodiment of the control method, before the pitch control proportion of the elevator and the 2N tilting rotors is allocated according to the current airspeed or dynamic pressure, the following rotor control process is further included:

[0033] The current tilting position of each tilting rotor is obtained.

[0034] 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.

[0035] 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.

[0036] The rotational speed of the 2N tilt rotors is gradually increased.

[0037] In an embodiment of the control method, the vertical take-off and landing 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 rotor control process, during the gradual increase of the rotational speed of the 2N tilt rotors, the rotational speed of the 2M fixed rotors is gradually reduced to a set rotational speed.

[0038] In an embodiment of the control method, the rotor control process further comprises the following take-off control process before the rotor control process:

[0039] The 2N tilt rotors are tilted to the vertical upward or inclined upward of the rotation axis;

[0040] The elevator is deflected downward;

[0041] The 2M fixed rotors and the 2N tilt rotors are started, and when the vertical take-off and landing aircraft reaches a set height, a level flight instruction is issued.

[0042] In an embodiment of the control method, the vertical take-off and landing aircraft further comprises 2M fixed rotors, and the 2M fixed rotors are distributed around the 2N tilt rotors. Before the distribution of the elevator and the pitch control ratio of the 2N tilt rotors according to the current airspeed or dynamic pressure, the following take-off control process is further included:

[0043] The 2N tilt rotors are tilted to the horizontal forward of the rotation axis;

[0044] The elevator is deflected downward;

[0045] The 2M fixed rotors and the 2N tilt rotors are started, and when the vertical take-off and landing aircraft reaches a set height, a level flight instruction is issued.

[0046] In an embodiment of the control method, after the take-off control process, the following rotor control process is further included before the pitch control: the rotational speed of the 2N tilt rotors is gradually increased, a forward flight instruction is issued, and the rotational speed of the 2M fixed rotors is gradually reduced to a set rotational speed.

[0047] In an embodiment of the control method, in the rotor control process, after the rotating speed of the 2M fixed rotors is gradually reduced to the set rotating speed, 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.

[0048] In an embodiment of the control method, the control method further comprises a ground preparation process before the take-off control process, and the ground preparation process comprises starting the VTOL aircraft, detecting system power-on, and confirming full stroke state of the servo system.

[0049] 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, and the control comprises differentially adjusting the pitch moment through the difference in tilting speed and / or the difference in tilting angle and / or the difference in rotating speed between the tilting rotors in different directions of the center of gravity to realize pitch trim and control.

[0050] 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 the cruising position, and the take-off transition flight is completed.

[0051] The VTOL aircraft is provided with elevators and 2N tilting rotors, in the VTOL 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 VTOL aircraft are located on the symmetry plane of the fuselage, and the point B is located on the side of the tail close to the point G. During the mode change process of the VTOL aircraft, the point B is always located on the side of the tail close to the point G. With this layout, the center of symmetry B of the tilting rotors and the center of gravity G of the VTOL aircraft are not coincident, especially during the transition process of the VTOL aircraft from the VTOL state to the cruising state, the points G and B move along the symmetry plane to the side close to the nose. Therefore, the pulling force of the front tilting rotors on the center of gravity G has a smaller moment, the pulling force of the rear tilting rotors on the center of gravity G has a larger moment, and the moment difference between the front and rear tilting rotors can resist part of the lifting moment of the tail caused by the washout area of the tilting rotors on the tail, thereby reducing the difficulty of pitch control. Therefore, under the condition that the tilting rotors on the front and rear sides of the center of gravity G have the same rotating speed, because of the length difference 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 washout area of the tilting rotors on the tail, thereby enabling the VTOL aircraft to better trim the pitch moment under the condition that the rotating speeds of the front and rear rotors are consistent.

[0052] The control method of the application can realize the pitch control through the linkage of the elevator and the 2N tilt rotors according to the current airspeed or dynamic pressure. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the 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 constitute some embodiments of the application, and for those skilled in the art, other embodiments can be obtained based on these drawings without creative labor.

[0054] Figure 1 The axial side view of the vertical take-off and landing aircraft in the vertical take-off and landing state in an embodiment of the application;

[0055] Figure 2 The side view of the vertical take-off and landing aircraft in the vertical take-off and landing state in an embodiment of the application;

[0056] Figure 3 The axial side view of the vertical take-off and landing aircraft in the vertical take-off and landing state in another embodiment of the application;

[0057] Figure 4 The side view of the vertical take-off and landing aircraft in the vertical take-off and landing state in another embodiment of the application;

[0058] Figure 5 The axial side view of the vertical take-off and landing aircraft in the cruising state in another embodiment of the application;

[0059] Figure 6 The axial side view of the vertical take-off and landing aircraft in the vertical take-off and landing state in another embodiment of the application;

[0060] Figure 7 The top view of the vertical take-off and landing aircraft in the vertical take-off and landing state in another embodiment of the application;

[0061] Figure 8 The side view of the vertical take-off and landing aircraft in the vertical take-off and landing state in another embodiment of the application;

[0062] Figure 9 The rear view of the vertical take-off and landing aircraft in the vertical take-off and landing state in another embodiment of the application;

[0063] Figure 10 The partial view of the full tilt rotor;

[0064] Figure 11 The partial view of the full tilt rotor after the removal of the pod shell;

[0065] Figure 12Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0066] Figure 13 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed; Figure 12 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0067] Figure 14 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0068] Figure 15 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0069] Figure 16 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed; Figure 14 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0070] Figure 17 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed; Figure 14 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0071] Figure 18 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0072] Figure 19 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0073] Figure 20 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0074] Figure 21 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0075] Figure 22 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0076] Figure 23 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0077] Figure 24 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0078] Figure 25 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0079] Figure 26 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0080] Figure 27 Figure 1 1 is a top view of the full tilt rotor with the nacelle shell removed;

[0081] Figure 28 Flow chart for one embodiment of the VTOL aircraft of the present application from ground state to cruise state;

[0082] Figure 29 Flow chart for one embodiment of the VTOL aircraft of the present application from takeoff to level flight;

[0083] Figure 30 Flow chart for one embodiment of the VTOL aircraft of the present application for pitch control;

[0084] Figure 31 Flow chart for one embodiment of the VTOL aircraft of the present application for rotor control;

[0085] Figure 32 Flow chart for one embodiment of the VTOL aircraft of the present application for takeoff control process;

[0086] Figure 33 Flow chart for one embodiment of the VTOL aircraft of the present application for takeoff control process;

[0087] Figure 34 Top view of the VTOL aircraft in the VTOL state in another embodiment of the present application.

[0088] Element number explanation

[0089] 10, fuselage; 20, wing; 30, tail; 31, elevator; 311, elevator 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 device; 4413, fairing; 442, power pod; 4421, tilt drive device; 4422, rocker arm; 4423, first shaft body; 4424, second shaft body; 4425, clamping structure; 44251, slit; 4426, connecting rod; 4427, first hinge shaft; 4428, second hinge 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, symmetry plane. DETAILED DESCRIPTION

[0090] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0091] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0092] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0093] Please see Figures 1 to 34 This 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.

[0094] 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 3The remaining structure and shape of the fuselage 10 are not limited, and can refer to the fuselage 10 structure of the existing vertical take-off and landing aircraft. The fuselage 10 includes avionics systems, flight control systems, electrical systems, navigation systems and other aircraft conventional operation systems, which are not described herein. The fuselage 10 is provided with wings 20 on both sides. The wings 20 on both sides are symmetrical relative to the symmetry plane 60 of the fuselage 10. The structure of the wings 20 can also refer to the fixed wing structure of the existing aircraft, which is not described herein. The tail 30 is provided at the tail of the fuselage 10. The tail 30 is integrally formed or mechanically connected with the fuselage 10 and is symmetrically arranged relative to the symmetry plane 60 of the fuselage 10. The tail 30 is provided with an elevator 31. The installation position and structure of the elevator 31 can be various, for example, the elevator 31 can be arranged at any suitable position on the tail 30, or can be any suitable elevator structure.

[0095] Key, please refer to Figure 7 2N tilt rotors are arranged on both sides of the fuselage 10, N is a natural number greater than or equal to 2, 2N tilt rotors are symmetrically arranged relative to the symmetry plane 60 of the fuselage 10, and a part of the 2N tilt rotors are arranged on the tail 30. 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 center of gravity 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. During the mode change of the vertical take-off and landing aircraft, the points G and B move along the symmetry plane, for example, during the transition 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. The point B is always located on the side of the point G close to the tail.

[0096] With the above layout, the center of gravity G of the vertical take-off and landing aircraft and the symmetry center B of the 2N tilt rotors do not coincide, and during the transition of the vertical take-off and landing aircraft from the vertical take-off state to the cruising state, the points G and B move along the symmetry plane 60 to the side close to the nose. Therefore, the pulling force generated by the front tilt rotors on the center of gravity G has a smaller moment, the pulling force generated by the rear tilt rotors on the center of gravity G has a larger moment, and the moment difference between the front and rear tilt rotors can resist the part of the lifting moment generated by the washout area of the tilt rotors on the tail 30, thereby reducing the difficulty of pitch control. Therefore, under the condition that the tilt rotors on both sides of the center of gravity G have the same speed and oil, because of the length difference of the force arm on the center of gravity G, a lowering moment is generated, which can offset or partially offset the lifting moment generated by the washout area of the tilt rotors on the tail 30, thereby balancing the pitch moment of the vertical take-off and landing aircraft under the condition that the oil of the front and rear tilt rotors is consistent.

[0097] In the vertical takeoff and landing (VTOL) aircraft of the present invention, in various states, such as cruise mode (flying horizontally), vertical takeoff and landing mode (taking off and landing vertically), and mode transition states (including transition from vertical takeoff to cruise mode and vice versa), the rotation axes between the tilt rotors can be arranged in parallel or non-parallel configurations. In some embodiments, during flight, the rotation axis of any tilt rotor on the tail fin 30 and the rotation axis of any tilt rotor at other locations are not parallel to each other on the plane of symmetry 60 of the fuselage 10. This non-parallel rotation axes allow different tilt rotors to provide torques in different directions, thereby controlling the overall pitch moment of the VTOL aircraft.

[0098] Although the tilting speeds of the individual tilt rotors can be the same, allowing for pitch control through other means, in one embodiment of the vertical takeoff and landing aircraft of the present invention, in various states, such as cruise mode flying horizontally, vertical takeoff and landing mode, and mode transition states (including transition from vertical takeoff to cruise mode and from cruise mode to vertical takeoff mode), there is a first difference between the tilting speed of any tilt rotor on the tail fin 30 and the tilting speed of any tilt rotor at other positions, and the first difference is not equal to 0. By setting a threshold for the first difference, the pitch force of the vertical takeoff and landing aircraft in various states can be adjusted by tilting the tilt rotors to obtain a larger pitch control torque.

[0099] Although the tiltrotors can rotate at the same speed and pitch control can be achieved through other means, in one embodiment of the vertical takeoff and landing (VTOL) aircraft of the present invention, in various states, such as cruise mode (flying horizontally), vertical takeoff and landing mode (taking off and landing vertically), and mode transition states (including transition from vertical takeoff to cruise mode and vice versa), there exists a second difference between the rotational speed of any tiltrotor on the tail fin 30 and the rotational speed of any tiltrotor at other positions, and this second difference is not equal to 0. By setting a threshold for this second difference, the pitch force of the VTOL aircraft in various states can be adjusted by controlling the rotational speed of the tiltrotors to obtain a larger pitch control torque. It should be noted that the first difference in tilting speed between the front tilt rotor (the tilt rotor located on the front side of the tilt rotor on the tail 30) and the tilt rotor on the tail 30 can also be combined with the second difference in rotational speed between the front tilt rotor and the tilt rotor on the tail 30 to achieve pitch moment control using multiple strategies.

[0100] Although the present invention can be as follows Figures 1 to 4 The description only includes 2N tiltrotors, but preferably, please refer to [link to relevant documentation]. Figure 7In another embodiment of the application, the VTOL aircraft comprises 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 are 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, which is located in the symmetry plane of the fuselage and coincides with point G or is located on the side of point G close to the tail. During the transition of the VTOL aircraft from the vertical take-off state to the cruising state, points G and B move along the symmetry plane to the side close to the nose, and 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.

[0101] Specifically, with the nose of the VTOL aircraft facing forward, the centers B of the 2N tilt rotors are located on the rear side of the centers A of the 2M fixed rotors, and the distance from A to B is L2, L2>0. As the 2N tilt rotors tilt forward, the center of gravity of the 2N tilt rotors, the center of gravity G of the VTOL aircraft, and the symmetry center B will move towards the nose. During the entire tilting process from the preset vertical take-off position (e.g., 90° tilt angle) of the 2N tilt rotors to the preset cruising position (e.g., 0° tilt angle), L2>0 is always true. At the same time, the center of gravity G of the VTOL aircraft is located on the front side of the symmetry center B of the 2N tilt rotors and on the front side of the symmetry center A of the 2M fixed rotors, the distance from A to G is L1, L1≥0, and as the 2N tilt 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 symmetry center of the fixed rotors or the symmetry center of the tilt rotors do not coincide, and during the transition of the VTOL aircraft from the vertical take-off state to the cruising state, points G and B move along the symmetry plane to the side close to the nose, and 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. Therefore, the moment of the pulling force generated by the tilt rotors and fixed rotors on the front side of the center of gravity G is smaller, and the moment of the pulling force generated by the tilt rotors and fixed rotors on the rear side of the center of gravity G is larger, and the difference in the moments of the front and rear rotors can resist part of the lifting moment generated by the wash flow area of the tilt rotors on the tail, thus reducing the difficulty of pitch control. Therefore, under the condition of the same rotational speed of the fixed rotors or tilt rotors on the front and rear sides of the center of gravity G, a lowering moment will 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 generated by the wash flow area of the tilt rotors on the tail, thus enabling the VTOL aircraft to better balance the pitch moment under the condition of consistent rotational speed of the front and rear rotors.

[0102] Further, in the tilt conversion phase of the tilt-rotor, the VTOL aircraft also generates an extra large nose-up moment due to aerodynamic interference, and during the tilting process of the tilt-rotor, the center of gravity G of the VTOL aircraft gradually moves towards the nose with the tilting process, and the center of symmetry B of the tilt-rotor also gradually moves towards the nose, since the center of gravity G is always in front of the center of symmetry B, therefore, the moment difference between the tilt-rotor in front of the center of gravity G and the tilt-rotor behind the center of gravity G during the entire tilting phase can also generate a part of the nose-down moment to offset or partially offset the nose-up moment caused by aerodynamic interference.

[0103] Further, in the tilting phase and the cruising phase, 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 close to the tail 30 of the point A, therefore, there is a relatively large longitudinal and heading static stability margin, the aircraft has stronger ability to resist extreme wind weather, and the flight is also safer.

[0104] Please refer to Figure 26 In an embodiment of the VTOL aircraft of the present application, the tail 30 is a V-tail, a third tilt-rotor 43 is installed on the wing tip of one side of the V-tail, and a fourth tilt-rotor 44 is installed on the wing tip of the other side of the V-tail, and the third tilt-rotor 43 and the fourth tilt-rotor 44 are symmetrical about the body symmetry plane 60. In the VTOL state, in the direction parallel to the rolling axis X of the aircraft, the distance between the rotation center of the tilt-rotor on the tail and the wing tip leading edge of the V-tail is t1, 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 tilt mechanism is connected to the wing tip of the tail 30 within the range, the thickness of the tail 30 is relatively thick, and the stress condition of the tail 30 is better.

[0105] In an embodiment of the VTOL aircraft of the present application, the tilt-rotor located on the tail is a full tilt-rotor, and the tilt-rotor located outside the tail is a partial tilt-rotor. In other embodiments, the tilt-rotor located outside the tail can also be a full tilt-rotor, especially when the tilt-rotor is installed on the wing tip, the tilt-rotor located on the wing tip can also be a full tilt-rotor. The existing tilt-rotor mainly includes a rotor and a power pod 442, and the power pod 442 can be installed with a motor and control components. The above-mentioned "partial tilt-rotor" mainly cuts off the power pod 442, and the part close to the rotor tilts with the rotor during the tilting process of the rotor, and the part away from the rotor is relatively fixed with the fuselage 10. In the above-mentioned "full tilt-rotor", the entire power pod 442 tilts with the corresponding rotor. It should be noted that if the installation conditions permit, the 2N tilt-rotors can all be full tilt-rotors, but considering that the existing tilt-rotors on the front side of the tail 30 of the fuselage 10 or the wing 20 are mainly installed on the arms. Please refer to Figures 1 to 6In the embodiment of the application, the tilting rotor on the tail wing 30 is a full-tilting rotor, and the tilting rotor on the front side of the fuselage 10 or the wing 20 is a partial-tilting rotor. The specific position and mounting mode of the partial-tilting rotor on the wing 20 or the fuselage 10 can not be limited. For example, the partial-tilting rotor can be directly mounted on the wing 20, or mounted on the wing 20 or the fuselage 10 through a boom.

[0106] In the embodiment of the application, the tilting rotor on the tail wing 30 is a full-tilting rotor, and the tilting rotor on the front side of the fuselage 10 or the wing 20 is a partial-tilting rotor. The specific position and mounting mode of the partial-tilting rotor on the wing 20 or the fuselage 10 can not be limited. For example, the partial-tilting rotor can be directly mounted on the wing 20, or mounted on the wing 20 or the fuselage 10 through a boom.

[0107] In the embodiment of the application, the tilting rotor on the tail wing 30 is a full-tilting rotor, and the tilting rotor on the front side of the fuselage 10 or the wing 20 is a partial-tilting rotor. The specific position and mounting mode of the partial-tilting rotor on the wing 20 or the fuselage 10 can not be limited. For example, the partial-tilting rotor can be directly mounted on the wing 20, or mounted on the wing 20 or the fuselage 10 through a boom. Figure 10 and Figure 18 In the embodiment of the application, the tilting rotor on the tail wing 30 is a full-tilting rotor, and the tilting rotor on the front side of the fuselage 10 or the wing 20 is a partial-tilting rotor. The specific position and mounting mode of the partial-tilting rotor on the wing 20 or the fuselage 10 can not be limited. For example, the partial-tilting rotor can be directly mounted on the wing 20, or mounted on the wing 20 or the fuselage 10 through a boom.

[0108] In the embodiment of the application, the tilting rotor on the tail wing 30 is a full-tilting rotor, and the tilting rotor on the front side of the fuselage 10 or the wing 20 is a partial-tilting rotor. The specific position and mounting mode of the partial-tilting rotor on the wing 20 or the fuselage 10 can not be limited. For example, the partial-tilting rotor can be directly mounted on the wing 20, or mounted on the wing 20 or the fuselage 10 through a boom. Figure 10 In the embodiment of the application, the tilting rotor on the tail wing 30 is a full-tilting rotor, and the tilting rotor on the front side of the fuselage 10 or the wing 20 is a partial-tilting rotor. The specific position and mounting mode of the partial-tilting rotor on the wing 20 or the fuselage 10 can not be limited. For example, the partial-tilting rotor can be directly mounted on the wing 20, or mounted on the wing 20 or the fuselage 10 through a boom.

[0109] 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 downwash area of the corresponding rotor during flight can be reduced.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] It should be noted that considering that the whole tilting mechanism is installed on one side, the longer extension distance of the first shaft body 4423 will increase the bending moment of the first shaft body 4423, preferably, please refer to Figure 12 In an embodiment, the first shaft body 4423 and the empennage 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.

[0115] In one embodiment of the present invention, the distance from the rotation center of the tilt drive 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 4423 to the axis of the first hinge shaft 4427 is c, and the distance from the center of the first shaft 4423 to the center of the second shaft 4424 is d. a is less than b, c, and d, respectively, c is greater than b and d, and the sum of a and c is less than the sum of b and d. Thus, if the tilt drive device 4421 malfunctions, causing its output shaft to remain in either forward or reverse rotation, the rocker arm 4422 will swing. That is, after rotating clockwise to its limit, the rocker arm 4422 will rotate counterclockwise, and after rotating counterclockwise to its limit, it will rotate clockwise. This limits the range of motion of the tilt mechanism, preventing it from rotating beyond its range and colliding or interfering with other components. It also prevents the front propeller from colliding with the fuselage and other structures due to excessive tilting, thus avoiding damage to the fuselage and other structures. Therefore, by adjusting the length ratio of each component in the tilting mechanism, this invention can constrain the tilting angle range of the tilting mechanism. Simultaneously, it cleverly solves the limiting problem of the tilting mechanism, ensuring that the extreme positions of both forward and reverse rotation are at the same limiting position on the connecting rod. This ingenious design not only effectively ensures the safety of the mechanism but also simplifies the design, eliminating the need for additional limiting mechanisms for extreme positions and maximizing the optimization of the installation space during the movement of the transmission rod mechanism. Specifically, by adjusting the length ratio of each component within the connecting rod mechanism... For example, the distance between the end axis of the drive arm 4429 (i.e., the axis of the second hinge shaft 4428) and the axis of the first shaft 4423 is equal in the initial angle state (i.e., the minimum tilt angle) and the final angle state (i.e., the maximum tilt angle). At this time, the angle between the plane formed by the end axis of the drive arm 4429 and the axis of the first shaft 4423 in the initial angle state and the plane formed by the end axis of the drive arm 4429 and the axis of the first shaft 4423 in the final angle state is equal to the angle of rotation of the rocker arm 4422 ± 5°. In this way, one limit point can constrain two directions.

[0116] 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 maintain the state at any position, maintain the current state position when driving fails, and continue to work after driving is restored, and can make the structural arrangement more concentrated.

[0117] 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 the 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°, etc.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] In an embodiment of the vertical take-off and landing aircraft, the spacing of the four fixed rotors along the extending direction of the fuselage, that is, the spacing between the second fixed rotor 52 and the fourth fixed rotor 54, or the spacing between the first fixed rotor 51 and the third fixed rotor 53, is L3. The spacing of the four tilting rotors along the extending direction of the fuselage, that is, the spacing between the second tilting rotor 42 and the fourth tilting rotor 44, or the spacing 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 a relatively large longitudinal and heading static stability margin is obtained, the aircraft has stronger resistance to extreme gales, and flight is safer.

[0122] 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.

[0123] 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.

[0124] The VTOL aircraft differs from that in Figures 1 to 4 , in another embodiment of the VTOL aircraft, 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.

[0125] 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.

[0126] Please refer to Figure 25 , in some embodiments, the chord length of the elevator plate 311 is 15% to 100% of the chord length of the tail 30, 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

[0127] 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 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 23 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 9 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

[0129] 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 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.

[0130] 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°.

[0131] 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.

[0132] 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.

[0133] In an embodiment of the vertical take-off and landing aircraft of the present application, the following method is used for pitch control:

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] S400, the cruising state. In the cruising state, the vertical take-off and landing aircraft performs level flight, and the aircraft navigates along the horizontal direction, which is relatively stable.

[0141] Referring to Figure 32 In an embodiment, the take-off control process of step S200 includes the following steps:

[0142] 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 between 0°-90° (excluding end point values) between the rotation axis of the tilt rotor and the roll axis;

[0143] S212, deflect the elevators 31 downward, so that the elevators 31 participate in the take-off control;

[0144] S213, start the 2N tilt rotors, and issue a level flight instruction when the vertical take-off and landing aircraft reaches a set height.

[0145] In the take-off process of S211 to S213, if the tilt-rotor is set to 90°, the VTOL aircraft takes off vertically normally, 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.

[0146] 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:

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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. For example, the cruise position can be a position where the tilt angle is 0° and the rotation axis of the tilt-rotor is parallel to the roll axis.

[0151] Please refer to Figure 31 In an embodiment, the rotor control process S320 includes the following steps:

[0152] 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 directly feed back the corresponding current tilt position to the central control system through the tilt driving device corresponding to the tilt-rotor.

[0153] 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°.

[0154] 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;

[0155] 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 2N tilt rotors needs to be gradually increased while the speed of the 2M fixed rotors needs to be gradually reduced to a set speed.

[0156] 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:

[0157] S221, tilt the 2N tilt rotors to the rotation axis horizontal forward, parallel to the roll axis X;

[0158] S222, deflect the elevator 31 downward;

[0159] S223, start 2M fixed rotors and 2N tilting rotors, and when the VTOL aircraft reaches the set height, issue the level flight instruction.

[0160] 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 ), and the aircraft becomes a compound wing mode. The aircraft is vertically taken off by the outer rotors, and the output of the outer rotors is twice that of the control scheme one. 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 successfully achieved. In this scheme, the tail wing 30 of the inner tilting rotor has the smallest blocking area and the smallest lifting moment, and the control is the simplest. It 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. Therefore, this control mode is reduced in non-emergency situations.

[0161] 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. 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.

[0162] 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 in 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:

[0163] 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 a more balanced pitch control through the pitch control proportion.

[0164] S333, according to the pitch control proportion, the elevators 31, 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 to balance the pitch impact force in the level flight process.

[0165] 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.

[0166] 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.

[0167] 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 airspeed or dynamic pressure in time, 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.

[0168] 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.

[0169] Please refer to Figure 27 , Figure 27 In order to generate the whole machine pitch moment curve by comparing 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 20The second curve 102 represents a partial tilt model, which is similar to... Figure 7 The only difference between the medium vertical takeoff and landing (VTOL) aircraft models is the structure of the tilt rotor on tail fin 30, which is a tilting scheme for the power pod section; otherwise, they are identical. In the simulation analysis of the two models, the four fixed rotors and the four tilt rotors rotate at the same speed and the thrust matches the aircraft's takeoff weight (thrust and gravity balance).

[0170] Figure 27 The first curve 101 and the second curve 102 are the pitch moment curves of the two models as a function of flight speed (i.e. wind speed). The flight speed in the figure has been dimensionless. The process from 0 to 1 is the maximum speed of the aircraft from the hovering state to the current tilt angle (keeping the above-mentioned 90° tilt angle unchanged), that is, from the minimum speed to the maximum speed at the current tilt angle. The pitch moment in the figure has also been dimensionless.

[0171] Depend on Figure 27 Comparing the first curve 101 and the second curve 102, it can be seen that without differential throttle adjustment of the eight rotors, the aircraft will generate a large pitch moment. Therefore, to achieve stable flight, the pitch moment needs to be trimmed to make the pitch angular acceleration zero. To trim this aerodynamic pitch moment, differential throttle adjustment of the rotors is required to cancel out the pitch moment generated by the rotor differential adjustment. The pod-based full tilt control method requires 0.25 units for maximum pitch trim and control during flight. In contrast, the power pod 442 partial tilt control method requires 0.8 units for maximum pitch trim and control across the entire aircraft, which is significantly greater than the full tilt control method. The larger the pitch moment generated during flight, the more difficult the aircraft is to control, and the greater the additional power required by the power system for attitude adjustment. Furthermore, from... Figure 27 The simulation curves also show that as the flight speed increases, the pitch trim and control requirements generated by the partial tilt control method of the power pod 442 fluctuate significantly, changing from -0.04 in the hovering state (dimensional wind speed of 0) to approximately 0.8 (dimensional wind speed of 0.57). The pitch moment fluctuation is extremely drastic, which is very detrimental to the aircraft's pitch control. In contrast, the pitch moment generated by the full tilt control method of the power pod 442 changes from -0.25 in the hovering state (dimensional wind speed of 0) to approximately 0.25 (dimensional wind speed of 0.42). The pitch moment fluctuation is small, which is beneficial to the control of the aircraft's pitch direction. Therefore, the vertical takeoff and landing aircraft and pitch control method provided by this invention are simple and effective, and can effectively improve aircraft safety.

[0172] 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.

[0173] The control method of the present application allocates the pitch control proportion of the elevators and 2N tilt rotors according to the current airspeed or dynamic pressure, and can realize pitch control through the linkage of the elevators and 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 takeoff and landing aircraft, characterized in that, include: The fuselage has wings on both sides and a tail fin at the rear, with an elevator on the tail fin. 2N tiltrotors are symmetrically mounted on both sides of the fuselage, and a portion of the 2N tiltrotors are located on the tail fin; Where 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 symmetrical about point B. Both point B and the center of gravity G of the vertical take-off and landing aircraft are located within the plane of symmetry of the fuselage, and point B is located on the side of point G closer to the tail fin. During the modal change of the vertical take-off and landing aircraft, both point G and point B move along the plane of symmetry, and point B is always located on the side of point G closer to the tail fin. The vertical takeoff and landing aircraft uses the following method for pitch control: During flight, 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.

2. The vertical takeoff and landing aircraft according to claim 1, characterized in that, During flight, the rotation axis of any tilt rotor on the tail fin and the rotation axis of any tilt rotor at other locations are not parallel in projection onto the plane of symmetry of the fuselage.

3. The vertical takeoff and landing aircraft according to any one of claims 1 to 2, characterized in that, In cruise mode and / or VTOL mode and / or mode transition mode, there is a first difference between the tilt speed of any tilt rotor on the tail fin and the tilt speed of any tilt rotor at other positions, and the first difference is not equal to 0.

4. The vertical takeoff and landing aircraft according to any one of claims 1 to 2, characterized in that, During cruise and / or VTOL and / or mode transition, there is a second difference between the rotational speed of any of the tilt rotors on the tail fin and the rotational speed of any of the tilt rotors at other positions, and the second difference is not equal to 0.

5. The vertical takeoff and landing aircraft according to claim 1, characterized in that, Controlling the 2N tilt rotors according to the pitch control ratio includes: The pitch moment is differentially adjusted by the difference in tilt angle between the tilt rotor on the tail fin and any other tilt rotor to perform pitch trim and control. And / or, by means of the difference in rotational speed between the tilt rotor on the tail fin and any other tilt rotor, differential adjustment of the pitch moment is used for pitch trim and control; And / or, differential adjustment of pitch moment for pitch trim and control via the difference in tilt speed between the tilt rotor on the tail and any other tilt rotor.

6. The vertical takeoff and landing aircraft according to claim 2, characterized in that, The vertical takeoff and landing aircraft includes four tilt rotors, which are symmetrically mounted on both sides of the fuselage. Two of the tilt rotors are symmetrically mounted on the wings about the fuselage, and the other two tilt rotors are symmetrically mounted on the tail.

7. The vertical takeoff and landing aircraft according to claim 2, characterized in that, The vertical takeoff and landing aircraft includes six tiltrotors, which are symmetrically mounted on both sides of the fuselage. Four of the tiltrotors are symmetrically mounted on the wings about the fuselage, and the other two tiltrotors are symmetrically mounted on the tail.

8. The vertical takeoff and landing aircraft according to claim 6 or 7, characterized in that, The tail fin is a V-shaped tail fin, and the two tilt rotors located on the tail fin are fully tilt rotors, which are respectively installed on the two wingtips on the upper part of the V-shaped tail fin.

9. The vertical takeoff and landing aircraft according to claim 6 or 7, characterized in that, Two tilt rotors are located at the wingtips of the wing, and the tilt rotors located at the wingtips are full tilt rotors.

10. The vertical takeoff and landing aircraft according to claim 1, 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. 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 takeoff and landing state, the projections of all the fixed rotors on the horizontal plane are centrally symmetrical about point A, which is located within the plane of symmetry of the fuselage. During the modal changes of the vertical takeoff and landing aircraft, point G is located on the side of point A closer to the nose or coincides with point A, and point B is always located on the side of point A closer to the tail.

11. The vertical takeoff and landing aircraft according to claim 10, characterized in that, The vertical takeoff and landing aircraft uses the following method for pitch control: During flight, the pitch control ratios of the elevator rudder, the 2N tilt rotors, and the 2M fixed rotors are distributed according to the current airspeed or dynamic pressure. According to the pitch control ratio, the elevator rudder, the 2N tilt rotors and the 2M fixed rotors are controlled respectively to achieve pitch trim and maneuvering.

12. The vertical takeoff and landing aircraft according to claim 10, characterized in that, The vertical takeoff and landing aircraft includes four tilt rotors and four fixed rotors. The four fixed rotors are symmetrically mounted on both sides of the fuselage, and the four tilt rotors are located inside the four fixed rotors. Two of the tilt rotors are symmetrically mounted on the tail fin, and the two tilt rotors on the tail fin are full tilt rotors.

13. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The tail fin is a V-shaped tail fin, on which two tilt rotors are mounted. The two tilt rotors are respectively mounted on the wingtips of the V-shaped tail fin. In the vertical take-off and landing (VTOL) state, along the direction parallel to the roll axis of the VTOL aircraft, the distance between the rotation center of the tilt rotor on the tail fin and the leading edge of the wingtip of the V-shaped tail fin is t1, and the chord length of the wingtip of the V-shaped tail fin is t2. The ratio of t1 to t2 is 15% to 40%.

14. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The tilt rotor located on the tail fin is a fully tilt rotor; the tilt rotor located outside the tail fin is a partially tilt rotor.

15. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The wingtip of the aircraft is equipped with a tilt rotor, and both the tilt rotor on the tail and the tilt rotor on the wingtip are full tilt rotors.

16. The vertical takeoff and landing aircraft according to claim 14 or 15, characterized in that, 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.

17. 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.

18. A control method for a vertical takeoff and landing aircraft as described in claim 1, characterized in that, 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.

19. The control method according to claim 18, characterized in that, 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.

20. The control method according to claim 19, characterized in that, 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.

21. The control method according to claim 19, 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; the 2M fixed rotors are symmetrically mounted on the wings on both sides of the fuselage and located outside the tilt rotors; 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.

22. The control method according to claim 21, characterized in that, 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.

23. The control method according to claim 18, 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; the 2M fixed rotors are symmetrically mounted on the wings on both sides of the fuselage and located outside the tilt rotors; Before allocating the elevator control ratio to the pitch control ratio of the 2N tilt rotors based on the current airspeed or dynamic pressure, the following takeoff control process is also included: Tilt all 2N tilt rotors so that the axis of rotation is horizontal and forward. 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.

24. The control method according to claim 23, characterized in that, After the takeoff control process and before the pitch control process, the following rotor control process is also included: gradually increasing the rotational speed of 2N tilt rotors, issuing a forward flight command, and gradually decreasing the rotational speed of 2M fixed rotors to the set speed.

25. The control method according to claim 22 or 24, characterized in that, During the rotor control process, after gradually reducing the rotational speed of 2M fixed rotors to the set rotational speed, the system also includes controlling the elevator rudder to return to zero according to the current airspeed or dynamic pressure, and gradually participating in the pitch control process.

26. The control method according to claim 22 or 24, characterized in that, The takeoff control process is preceded by a ground preparation process, which includes: starting the vertical takeoff and landing aircraft, powering on and testing the system, and confirming the status of the servo system throughout its entire flight.

27. The control method according to any one of claims 18 to 24, characterized in that, According to the pitch control ratio, the elevator rudder and the 2N tilt rotors are controlled respectively to achieve pitch trim and control, including: differentially adjusting the pitch torque to perform pitch trim and control by using the tilt speed difference and / or tilt angle difference and / or rotation speed difference between the tilt rotors at different positions.

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