Vertical take-off and landing aircraft and control method for vertical take-off and landing aircraft

Abstract

A vertical take-off and landing aircraft and a control method for the vertical take-off and landing aircraft include a vertical take-off and landing aircraft comprising an airframe (10), four tilt rotors, and four fixed rotors. Main wings (20) are symmetrically installed on both sides of the airframe (10), and the four tilt rotors are attached to the front and rear of the main wings (20) on each side, respectively, and are symmetrical in pairs about a longitudinal symmetry plane (11) of the airframe (10), with a spacing A between the tilt rotors on the front side of the main wings (20) and a spacing B between the tilt rotors on the rear side of the main wings (20), with a deviation between A and B not greater than 0.2*(A+B) / 2. The four fixed rotors are attached to the outsides of the tilt rotors and are located on the front and rear sides of the main wings (20), respectively, and are symmetrical in pairs about the longitudinal symmetry plane (11). The spacing between the fixed rotors on the front side of the main wing (20) is C, the spacing between the fixed rotors on the rear side of the main wing (20) is D, and the deviation between C and D is less than 0.05*(C+D) / 2.

Description

[Technical Field]

[0001] The present invention relates to the technical field of aircraft, and more particularly to a vertical take-off and landing aircraft and a method for controlling a vertical take-off and landing aircraft. [Background technology]

[0002] Vertical takeoff and landing (VTOL) fixed-wing aircraft (distributed propulsion) combine the vertical takeoff and landing capabilities of helicopters with the efficient, high-speed horizontal flight capabilities of fixed wings. They are quieter, more comfortable, and more economical than helicopters, more efficient, and have a longer range than multirotors. Compared to fixed-wing aircraft, they are capable of vertical takeoff and landing on urban landing platforms, making them an ideal choice for urban air travel. The mainstream layouts for VTOL fixed-wing aircraft are generally classified into three types: composite wing layouts, full tilt layouts, and partial tilt layouts. Each layout has its own advantages and disadvantages, making it difficult to achieve an optimal balance. In composite wing layouts, the power system is relatively heavy during horizontal flight, accounting for a relatively large proportion of the power system's weight. Furthermore, the horizontal flight resistance of composite wings is also significant due to the impact of the lifting propellers. The combined effect of these two factors results in relatively low maximum flight speeds and range performance for composite wings. Full tilt layouts not only have a complex mechanical structure, but also more complex aerodynamic characteristics and control. Generally, its safety is inferior to that of a composite wing, and a partially tilted layout is expected to combine the advantages of both, but the currently disclosed partially tilted configuration does not have both advantages simultaneously. Therefore, in order to better balance the flight performance, safety, reliability, and technical difficulty of vertical take-off and landing fixed-wing aircraft, it is necessary to propose a new vertical take-off and landing fixed-wing aircraft layout that balances the advantages and disadvantages and achieves a better balance. Summary of the Invention [Problem to be solved by the invention]

[0003] In view of the above-mentioned drawbacks of the prior art, the present invention provides a vertical take-off and landing aircraft and a control method for a vertical take-off and landing aircraft that optimizes the layout type of the vertical take-off and landing aircraft in the prior art. [Means for solving the problem]

[0004] To achieve the above and other related objectives, the present invention provides a vertical take-off and landing aircraft having an airframe, four tilt rotors, and four fixed rotors. Main wings are installed symmetrically on both sides of the aircraft, and four tilt rotors are installed in front of and behind the main wings on both sides, with their positions, rotation directions, and mounting angles corresponding to each other in pairs and symmetrical about the vertical symmetry plane of the aircraft, the distance between the two tilt rotors on the front side of the main wings is A, the distance between the two tilt rotors on the rear side of the main wings is B, and the deviation between A and B is 0.2*(A+B) / 2 or less, and four fixed rotors are installed outboard of the tilt rotors on both sides of the aircraft, respectively, and are located in front of and behind the main wings, with their positions, rotation directions, and mounting angles corresponding to each other in pairs and symmetrical about the vertical symmetry plane, the distance between the two fixed rotors on the front side of the main wings is C, and the distance between the two fixed rotors on the rear side of the main wings is D, and the deviation between C and D is 0.05*(C+D) / 2 or less. Here, in a vertical takeoff state, projections of the four tilt rotors on a horizontal plane correspond to each other in pairs and are centrally symmetrical about the center of gravity of the vertical takeoff and landing aircraft within a first set range, their positions are symmetrical about a vertical plane that passes through the center of gravity and is perpendicular to the vertical symmetry plane, the vertical interval between the horizontal projections of the tilt rotors is M, and the first set range is such that the vertical deviation between the intersection of the diagonal lines of the horizontal projections of the four tilt rotors and the horizontal projection of the center of gravity is 0.1*M or less, and projection centers of the four fixed rotors on a horizontal plane correspond to each other in pairs and are centrally symmetrical about the center of gravity within a second set range, their positions are symmetrical about the vertical plane, the vertical interval between the fixed rotors is N, and the second set range is such that the vertical deviation between the intersection of the diagonal lines of the horizontal projections of the four fixed rotors and the horizontal projection of the center of gravity is 0.1*N or less.

[0005] In one example of the vertical take-off and landing aircraft of the present invention, the tilt rotors on the front and / or rear sides of the main wing are attached to the main wing via arms.

[0006] In one example of the vertical take-off and landing aircraft of the present invention, the tilt rotors on the front and / or rear sides of the main wing are attached to the airframe via arms.

[0007] In one example of the vertical take-off and landing aircraft of the present invention, the tilt rotor on the front side of the main wing is attached to the main wing via an arm, and the tilt rotor on the rear side of the main wing is attached to the airframe via an arm.

[0008] In one example of the vertical take-off and landing aircraft of the present invention, a tail is provided at the tail section of the aircraft, and the tail is one of a V-tail, Y-tail, H-tail, X-tail, T-tail, π-tail, or U-tail.

[0009] In one example of a VTOL aircraft of the present invention, the two tilt rotors are attached to the tail and provide forward thrust as the aircraft moves forward, and can be tilted upward to provide vertical thrust when the aircraft is in a vertical takeoff position.

[0010] In one example of the vertical take-off and landing aircraft of the present invention, the tail is a V-tail, and the two tilt rotors on the rear side of the wings are attached to the wingtips on both sides of the upper part of the tail, respectively.

[0011] In one example of a vertical take-off and landing aircraft of the present invention, arms are provided on the main wings on both sides of the aircraft, and the four fixed rotors are symmetrically attached to the arms on both sides of the aircraft, and are located respectively in front of and behind the main wings.

[0012] In one example of the vertical take-off and landing aircraft of the present invention, the four tilt rotors include at least two fully tilting tilt rotors, and all of the fully tilting tilt rotors are symmetrically positioned with respect to the plane of symmetry of the vehicle.

[0013] The present invention further provides a control method for a vertical take-off and landing aircraft according to any one of the above claims, the control method including the following process of transitioning from vertical take-off to horizontal flight and / or from horizontal flight to vertical landing: The transition process from vertical takeoff to horizontal flight is a power system tilting the four tilt rotors forward according to a forward flight command; and setting the tilt speed of the four tilt rotors and the thrust distribution between the four tilt rotors and the four fixed rotors in accordance with a climb command, thereby controlling the climb speed and climb gradient of the vertical take-off and landing aircraft; The transition process from horizontal flight to vertical landing is a powered system tilting the four tilt rotors upward to a vertical takeoff and landing position according to a speed command; and setting the tilt speed of the four tilt rotors and the thrust distribution between the four tilt rotors and the four fixed rotors in accordance with a descent command, thereby controlling the descent speed and descent gradient of the vertical take-off and landing aircraft.

[0014] An example of the control method of the present invention further includes a control process when the aircraft accidentally enters a spin or stall and / or a control process when a crosswind is encountered, and / or a control process when a crosswind is encountered, the control process in the event of an erroneous spin or stall includes actuating the four fixed rotors to assist attitude control to recover from the spin or stall condition; The crosswind control process involves using thrust differentials of the four tilt rotors to assist yaw control and resist crosswinds when wind speed exceeds a set threshold.

[0015] The vertical take-off and landing aircraft of the present invention employs a unique bilaterally symmetrical layout (a vertical plane of symmetry and a vertical plane passing through the center of gravity and perpendicular to the vertical plane of symmetry) to define the spacing of the tilt rotors, the spacing of the fixed rotors, and the positions of their diagonals. Furthermore, during vertical take-off, the horizontal projections of the four tilt rotors are all centrosymmetric within a first set range with respect to the center of gravity of the vertical take-off and landing aircraft. At the same time, the fixed rotors are located outside the tilt rotors on both sides, and the horizontal projections of the four fixed rotors are all centrosymmetric within a second set range with respect to the center of gravity of the vertical take-off and landing aircraft. This layout reduces the required thrust output by the remaining power group in the event of a single rotor failure, ensuring safe aircraft flight. Furthermore, the present invention combines the advantages of a composite wing layout, a full tilt layout, and a partial tilt layout configuration through its unique layout. This layout method not only improves stability and reduces the difficulty of designing and installing a vertical take-off and landing aircraft, which is beneficial for accelerating the product commercialization process. In addition, compared to a layout in which the tilt rotors are installed on the outside, installing all tilt rotors inside the fixed rotor can reduce the yaw moment after a partial tilt rotor failure, significantly reduce the requirements for vertical tail capacity (vertical tail area x tail arm), and expand the safe flight envelope after a partial tilt rotor failure. [Brief explanation of the drawings]

[0016] In order to more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the drawings that need to be used in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0017] [Figure 1] 1 is an axonometric view of a vertical take-off and landing aircraft according to an embodiment of the present invention in a vertical take-off state. FIG. [Figure 2]FIG. 2 is a top view of the vertical take-off and landing aircraft of FIG. 1. [Figure 3] FIG. 2 is a front view of the vertical take-off and landing aircraft of FIG. 1. [Figure 4] FIG. 4 is a right side view of FIG. 3. [Figure 5] FIG. 2 is an axonometric view of the vertical take-off and landing aircraft of FIG. 1 in horizontal flight. [Figure 6] FIG. 6 is a top view of FIG. 5. [Figure 7] FIG. 6 is a front view of FIG. 5. [Figure 8] FIG. 8 is a side view of FIG. [Figure 9] FIG. 10 is an axonometric view of another embodiment of the vertical take-off and landing aircraft of the present invention in a vertical take-off state. [Figure 10] FIG. 10 is a top view of the vertical take-off and landing aircraft of FIG. [Figure 11] FIG. 10 is a front view of the vertical take-off and landing aircraft of FIG. [Figure 12] FIG. 12 is a side view of FIG. [Figure 13] FIG. 10 is an axonometric view of the vertical take-off and landing aircraft of FIG. 9 in horizontal flight. [Figure 14] FIG. 14 is a top view of FIG. [Figure 15] FIG. 14 is a front view of FIG. 13. [Figure 16] FIG. 16 is a side view of FIG. [Figure 17] FIG. 2 is a front view of another embodiment of the vertical take-off and landing aircraft of the present invention. [Figure 18] FIG. 18 is a top view of the vertical take-off and landing aircraft of FIG. [Figure 19] FIG. 18 is a side view of the vertical take-off and landing aircraft of FIG. [Figure 20] FIG. 18 is an axonometric view of the vertical takeoff and landing aircraft of FIG. 17 in a vertical takeoff state. [Figure 21] FIG. 18 is an axonometric view of the vertical take-off and landing aircraft of FIG. 17 in horizontal flight. [Figure 22] FIG. 2 is a front view of another embodiment of the vertical take-off and landing aircraft of the present invention. [Figure 23] FIG. 23 is a top view of the vertical take-off and landing aircraft of FIG. [Figure 24] FIG. 23 is a side view of the vertical take-off and landing aircraft of FIG. [Figure 25] FIG. 23 is an axonometric view of the vertical takeoff and landing aircraft of FIG. 22 in a vertical takeoff state. [Figure 26] FIG. 23 is an axonometric view of the vertical take-off and landing aircraft of FIG. 22 in horizontal flight. [Figure 27] FIG. 10 is a three-dimensional view of yet another embodiment of the vertical take-off and landing aircraft of the present invention in a vertical take-off state. [Figure 28] FIG. 10 is a three-dimensional view of yet another embodiment of the vertical take-off and landing aircraft of the present invention in horizontal flight. [Figure 29] FIG. 10 is a rear view of yet another embodiment of the vertical take-off and landing aircraft of the present invention in a vertical take-off state. [Figure 30] FIG. 10 is a three-dimensional view of yet another embodiment of the vertical take-off and landing aircraft of the present invention in a vertical take-off state. [Figure 31] FIG. 2 is a three-dimensional view of another embodiment of the vertical take-off and landing aircraft of the present invention in horizontal flight. [Figure 32] FIG. 1 is a schematic diagram of an embodiment of a control method for a vertical take-off and landing aircraft of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described through specific examples. However, those skilled in the art will easily understand other advantages and effects of the present invention from the disclosure of this specification. The present invention can be implemented or applied through other different specific embodiments, and various details of this specification can be modified or changed in various ways based on various viewpoints and applications without departing from the spirit of the present invention. The following examples and features in the examples may be combined if they are not inconsistent. It should also be understood that the terms used in the examples of the present invention are intended to describe specific implementation means and are not intended to limit the scope of protection of the present invention. In the following examples, test methods for which specific conditions are not specified generally follow conventional conditions or conditions recommended by each manufacturer.

[0019] When numerical ranges are given in the examples, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected unless otherwise specified in the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention are consistent with the understanding of a person skilled in the art in the prior art and the description of the present invention, and the present invention may be practiced using any methods, devices, and materials in the prior art that are similar or equivalent to the methods, devices, and materials described in the examples of the present invention.

[0020] In addition, terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are used only for convenience of explanation and do not limit the scope of the present invention. As long as the technical content is not substantially changed, changes or adjustments to the relative relationships are also considered to be within the scope of the present invention.

[0021] Referring to Figures 1 to 32, the present invention provides a vertical take-off and landing aircraft and a control method for a vertical take-off and landing aircraft that optimizes the layout type of a vertical take-off and landing aircraft in the prior art, particularly a layout type suitable for an eVTOL manned aircraft.

[0022] 1 to 17 , the vertical take-off and landing aircraft includes an airframe 10, four tilt rotors, and four fixed rotors. The airframe 10 has a symmetrical structure and a longitudinal symmetry plane 11 extending along the length of the airframe (i.e., the vertical plane along which the line ab in FIG. 2 is located). The other structures and shapes of the airframe 10 are not limited and may refer to the structures of the airframes 10 of conventional aircraft. For example, conventional aircraft operation systems, such as an avionics system, a flight control system, an electrical system, and a navigation system, are mounted on the airframe 10. Main wings 20 are provided on both sides of the airframe 10, and the main wings 20 on both sides are symmetrical with respect to the longitudinal symmetry plane 11 of the airframe 10. The structure of the main wings 20 may refer to the structure of the fixed wing 20 of conventional aircraft, and therefore will not be further described here. In the present invention, the four tilt rotors are respectively referred to as a first tilt rotor 41, a second tilt rotor 42, a third tilt rotor 43, and a fourth tilt rotor 44. The first tilt rotor 41 and the second tilt rotor 42 are attached to the front side of the main wing 20, with the first tilt rotor 41 located on one side of the airframe 10 and the second tilt rotor 42 located on the other side of the airframe 10. The third tilt rotor 43 and the fourth tilt rotor 44 are attached to the rear side of the main wing 20 and are respectively located on both sides of the airframe 10. The positions, rotation directions, and mounting angles of the first tilt rotor 41 and the second tilt rotor 42 are symmetrical with respect to the longitudinal symmetry plane 11 of the airframe 10, and the positions, rotation directions, and mounting angles of the third tilt rotor 43 and the fourth tilt rotor 44 are symmetrical with respect to the longitudinal symmetry plane 11 of the airframe 10. The distance between the first tilt rotor 41 and the second tilt rotor 42 on the front side of the main wing 20 is A, and the distance between the third tilt rotor 43 and the fourth tilt rotor 44 on the rear side of the main wing 20 is B, with the deviation between A and B being 0.2*(A+B) / 2 or less. This setting allows the rotor operating speed during vertical takeoff to be as uniform as possible, which is advantageous for standardizing the power system. Furthermore, the rotor arrangement can be maintained as symmetrical as possible with respect to the center of gravity, which is advantageous for unifying emergency response strategies.

[0023] As shown in FIG. 2 , the four fixed rotors are referred to as a first fixed rotor 51, a second fixed rotor 52, a third fixed rotor 53, and a fourth fixed rotor 54. The first fixed rotor 51 and the fourth fixed rotor 54 are located on the same side of the airframe 10 and are located outboard of the first tilt rotor 41 and the fourth tilt rotor 44 in the span direction. The first fixed rotor 51 is located on the front side of the main wing 20, and the fourth fixed rotor 54 is located on the rear side of the main wing 20. The second fixed rotor 52 and the third fixed rotor 53 are located on the other side of the airframe 10 and are located outboard of the second tilt rotor 42 and the third tilt rotor 43 in the span direction. The second fixed rotor 52 is located on the front side of the main wing 20, and the third fixed rotor 53 is located on the rear side of the main wing 20. The positions, rotation directions and mounting angles of the first fixed rotor 51 and the second fixed rotor 52 are symmetrical with respect to the longitudinal symmetry plane 11, and the positions, rotation directions and mounting angles of the third fixed rotor 53 and the fourth fixed rotor 54 are symmetrical with respect to the longitudinal symmetry plane 11. The distance between the first fixed rotor 51 and the second fixed rotor 52 on the front side of the main wing is C, the distance between the third fixed rotor 53 and the fourth fixed rotor 54 on the rear side of the main wing is D, and the deviation between C and D is 0.05*(C+D) / 2 or less.

[0024] 2, in a vertical takeoff state, the projections of the first tilt rotor 41 and the third tilt rotor 43 on a horizontal plane are centrosymmetrical with respect to the center of gravity (point G) of the vertical takeoff and landing aircraft within a first set range, and the projections of the second tilt rotor 42 and the fourth tilt rotor 44 on a horizontal plane are centrosymmetrical with respect to the center of gravity of the vertical takeoff and landing aircraft within the first set range. The positions of the horizontal projections of the first tilt rotor 41 and the fourth tilt rotor 44 are symmetrical with respect to a vertical plane 12 that passes through the center of gravity and is perpendicular to the longitudinal plane of symmetry 11 (i.e., the vertical plane on which the line cd in FIG. 2 is located). The positions of the horizontal projections of the second tilt rotor 42 and the third tilt rotor 43 are symmetrical with respect to a vertical plane 12 that passes through the center of gravity G and is perpendicular to the longitudinal plane of symmetry 11. The longitudinal distance between the horizontal projections of the first tilt rotor 41 and the fourth tilt rotor 44 and the longitudinal distance between the horizontal projections of the second tilt rotor 42 and the third tilt rotor 43 are both M, and the first set range is a longitudinal deviation of the horizontal projection of the center of gravity at the intersection of the line connecting the diagonals of the horizontal projections of the first tilt rotor 41 and the third tilt rotor 43 and the line connecting the diagonals of the horizontal projections of the second tilt rotor 42 and the fourth tilt rotor 44 from 0.1×M or less.

[0025] 2, in the vertical takeoff state, the centers of projection on the horizontal plane of the first fixed rotor 51 and the third fixed rotor 53 are centrosymmetrical with respect to the center of gravity within a second set range, and the centers of projection on the horizontal plane of the second fixed rotor 52 and the fourth fixed rotor 54 are centrosymmetrical with respect to the center of gravity within a second set range. The positions of the horizontal projections of the first fixed rotor 51 and the fourth fixed rotor 54 are symmetrical with respect to a vertical plane 12 that passes through the center of gravity and is perpendicular to the vertical plane of symmetry 11, and the positions of the horizontal projections of the second fixed rotor 52 and the third fixed rotor 53 are symmetrical with respect to a vertical plane 12 that passes through the center of gravity and is perpendicular to the vertical plane of symmetry 11. The vertical distance between the horizontal projections of the first fixed rotor 51 and the fourth fixed rotor 54 and the vertical distance between the horizontal projections of the second fixed rotor 52 and the third fixed rotor 53 are both N, and the second setting range is that the vertical deviation of the intersection of the line connecting the diagonal lines of the horizontal projections of the first fixed rotor 51 and the third fixed rotor 53 and the line connecting the diagonal lines of the horizontal projections of the second fixed rotor 52 and the fourth fixed rotor 54 from the horizontal projection of the center of gravity is 0.1 × N or less.

[0026] The specific positions and mounting methods of the tilt rotors described in the present invention on the airframe 10 and / or main wing 20 are not particularly limited as long as the constraints on the positional relationship described above are satisfied. For example, the tilt rotors on the front and rear sides of the main wing 20 may be mounted to the main wing 20 via arms, or the tilt rotors on the front and / or rear sides of the main wing 20 may be mounted to the airframe 10 via branched arms, or the tilt rotor on the front side of the main wing 20 may be mounted to the main wing 20 via arms, and the tilt rotor on the rear side of the main wing 20 may be mounted to the airframe 10 or the tail 30 via branched arms, or similarly, the tilt rotor on the front side of the main wing 20 may be mounted to the airframe 10 via branched arms, and the tilt rotor on the rear side of the main wing 20 may be mounted to the main wing 20 via arms. As shown in Figures 1 to 8, the first tilt rotor 41 and the second tilt rotor 42 are attached to the main wing 20 via arms, but as shown in Figures 9 to 16, they may also be attached to the fuselage 10 in front of the main wing 20 via a first branch arm 60.

[0027] 2 and 10, a first arm 511 is attached to the main wing 20 on one side of the airframe 10, and a second arm 521 is attached to the main wing 20 on the other side of the airframe 10. The first arm 511 and the second arm 521 are installed symmetrically with respect to the longitudinal symmetry plane 11 of the airframe 10, and the four fixed rotors are symmetrically attached to the first arm 511 and the second arm 521 on both sides of the airframe 10, respectively, and are located at the front and rear sides of the main wing 20 and the front and rear ends of the first arm 511 and the second arm 521, respectively. At the same time, the projections of all the fixed rotors on the horizontal plane are nearly centrosymmetric with two corresponding rotors with respect to the center of gravity of the VTOL aircraft. In the present invention, the fixed rotors are located outside all of the tilt rotors, and may be located outside in any direction, and the specific direction is not limited. However, in order to optimize the structure and reduce weight, in this embodiment, it is preferable that the four fixed rotors are located outside all of the tilt rotors in the span direction.

[0028] In one embodiment of the present invention, a tail unit 30 is provided at the tail of the aircraft 10. The tail unit 30 is integrally formed with or mechanically connected to the aircraft 10 and is symmetrical about the longitudinal symmetry plane 11 of the aircraft 10. The tail unit is one of a V-tail, a Y-tail, an H-tail, an X-tail, a T-tail, and a U-tail. However, in some other embodiments, the tail unit 30 may not be provided. Referring to FIG. 2 , in one embodiment of the present invention, the tail unit 30 is a V-tail, two of the four tilt rotors are attached to the tail unit 30, and the remaining tilt rotors are attached to the aircraft 10 and / or the main wings 20. In a vertical takeoff state, the horizontal projections of all the tilt rotors are approximately centrosymmetrical with respect to the center of gravity of the vertical takeoff and landing aircraft. Fixed rotors are provided outside the tilt rotors on both sides, and the horizontal projections of all the fixed rotors are approximately centrosymmetrical with respect to the center of gravity of the vertical takeoff and landing aircraft. This layout type reduces the required thrust output by the remaining power group in the event of a single rotor failure. The present invention not only combines the advantages of the composite wing layout, full tilt layout, and partial tilt layout configurations, but also mitigates the transition corridor reduction problem caused by tilt, easing the difficulty of designing and installing a VTOL, contributing to the rapid advancement of the product commercialization process. Furthermore, compared to a layout with tilt rotors installed outboard, this layout method, in which all tilt rotors are installed inside the fixed rotors, can reduce the yaw moment after a partial tilt rotor failure, significantly reduce the vertical stabilizer capacity requirements, and extend the safe flight envelope after a partial tilt rotor failure.

[0029] In one embodiment of the vertical take-off and landing aircraft of the present invention, at least some of the four tilt rotors are disposed forward of the center of gravity and at least some are disposed aft of the center of gravity. At least some of the four tilt rotors are disposed forward of the center of gravity of the vertical take-off and landing aircraft and at least some are disposed aft of the center of gravity of the vertical take-off and landing aircraft. This achieves a balance between multiple couples and makes the vertical take-off and landing process of the vertical take-off and landing aircraft more stable. Preferably, referring to FIGS. 2 and 10 , the four fixed rotors are symmetrically mounted on both sides of the airframe 10, the four tilt rotors are located inward of the four fixed rotors, two tilt rotors are mounted on the tail 30, and two tilt rotors are mounted on the airframe 10 or the main wings 20 forward of the main wings. A third arm 411 is provided on the main wing 20 on one side of the airframe 10, and a symmetrical fourth arm 421 is provided on the main wing 20 on the other side of the airframe 10, with a first tilt rotor 41 attached to the third arm 411 and a second tilt rotor 42 attached to the fourth arm 421, and these are installed symmetrically to the first tilt rotor 41 with respect to the longitudinal symmetry plane 11 of the airframe 10. A fifth arm 431 is provided on the tail fin 30 on one side of the airframe 10, and a symmetrical sixth arm 441 is provided on the tail fin 30 on the other side of the airframe 10, and the third tilt rotor 43 is attached to the fifth arm 431, and a fourth tilt rotor 44 is attached to the sixth arm 441, and these are installed symmetrically to the third tilt rotor 43 with respect to the symmetry plane of the airframe 10. The third tilt rotor 43 and the fourth tilt rotor 44 are installed symmetrically with respect to the plane of symmetry of the airframe 10. The first fixed rotor 51 and the second fixed rotor 52 are symmetrical with respect to the longitudinal plane of symmetry 11 of the airframe 10, and the third fixed rotor 53 and the fourth fixed rotor 54 are also symmetrical with respect to the longitudinal plane of symmetry of the airframe 10. The rotation axes of all four fixed rotors extend vertically upward. The projections of the first fixed rotor 51 and the third fixed rotor 53 on a horizontal plane are approximately centrosymmetric with respect to the center of gravity of the vertical take-off and landing aircraft, and the projections of the second fixed rotor 52 and the fourth fixed rotor 54 on a horizontal plane are approximately centrosymmetric with respect to the center of gravity of the vertical take-off and landing aircraft.In this application, the term "forward" refers to the direction extending toward the nose of the aircraft, and the term "aft" refers to the direction extending toward one side of the tail 30.

[0030] 18 to 22, the present invention further provides a vertical take-off and landing aircraft. This vertical take-off and landing aircraft differs from the vertical take-off and landing aircraft of FIG. 2 in that the tail 30 of the vertical take-off and landing aircraft is T-shaped, and the third tilt rotor 43 and the fourth tilt rotor 44 are not attached to the tail 30 but are attached to the fuselage between the tail 30 and the main wing 20 via a second branch arm 90. In this solution, the four inner tilt rotors are also approximately centrosymmetric with respect to the center of gravity of the vertical take-off and landing aircraft, and the four outer fixed rotors are also approximately centrosymmetric with each other, with each rotor corresponding to a corresponding rotor. This layout also has the advantages of the vertical take-off and landing aircraft of FIG. 2.

[0031] 22 to 26, the present invention further provides a vertical take-off and landing aircraft. The difference between this vertical take-off and landing aircraft and the vertical take-off and landing aircraft of FIG. 2 is that the third tilt rotor 43 and the fourth tilt rotor 44 are not attached to the V-tail 30, but are attached to the fuselage between the tail 30 and the main wing 20 via a second branch arm 90. In this solution, the four inner tilt rotors are also arranged in pairs approximately centrosymmetrically with respect to the center of gravity of the vertical take-off and landing aircraft, and the four outer fixed rotors are also arranged in pairs approximately centrosymmetrically with respect to the center of gravity of the vertical take-off and landing aircraft. This layout also has the advantages of the vertical take-off and landing aircraft of FIG. 2.

[0032] In the present invention, the tilt rotors on the tail fin 30 are attached to the upper side of the tail fin 30 and tilt upward during vertical takeoff. This reduces the possibility of the rotors harming passengers when boarding or disembarking the aircraft. Referring to Figures 1 to 17, in one embodiment of the vertical takeoff and landing aircraft of the present invention, the tail fin 30 is a V-tail, and two tilt rotors are attached to the tail fin 30, and the two tilt rotors are attached to the wingtips on both sides of the upper part of the tail fin 30, respectively. In other embodiments, any one of the above shapes may be used.

[0033] 12, in the present invention, the tilt rotor includes a tilt propeller 401 and a tilt drive unit (not shown). The base of the tilt drive unit is fixedly attached to the front side of the tail unit 30 or the main wing 20, and the tilt propeller 401 is attached to the drive end of the tilt drive unit and can be tilted and locked between the horizontal and vertical directions. The specific structures of the tilt drive unit and tilt propeller 401 can be found in the prior art and will not be described in detail here.

[0034] In one embodiment of the vertical take-off and landing aircraft of the present invention, the tilt rotor on the front side of the main wing 20 is attached to the fuselage 10 on the front side of the main wing 20 via a first branch arm 60, and the shape of the first branch arm 60 corresponds to the shape of the tail fin 30. The tilt rotor on the tail fin 30 is higher than the tilt rotor on the front side of the main wing 20.

[0035] Conventional tilt rotors include "full tilt rotors" and "partial tilt rotors." Both conventional "full tilt rotors" and "partial tilt rotors" include a rotor and a nacelle. Lift is generated by the rotation of the rotor, and the nacelle may be equipped with a motor or other control device that rotates the rotor. In "partial tilt rotors," the nacelle is often disconnected. When the rotor is tilted, the portion closer to the rotor tilts with the rotor, and the portion farther from the rotor is fixed relative to the aircraft. In "full tilt rotors," the entire nacelle tilts with the corresponding rotor. Considering the complexity of the airflow field during flight and flight safety, it is extremely difficult to arrange tilt rotors and fixed rotors to optimize the airflow interference prevention performance and flight stability of a vertical take-off and landing aircraft. In this application, all four tilt rotors can be "partially tilting tilt rotors" or all can be "fully tilting tilt rotors", but some can also be "partially tilting tilt rotors" and some can be "fully tilting tilt rotors".

[0036] 27 and 28, the present invention further provides a vertical take-off and landing aircraft. The difference between this vertical take-off and landing aircraft and the vertical take-off and landing aircraft of FIG. 2 is that the four tilt rotors include at least two fully tilting tilt rotors, and all of the fully tilting tilt rotors are installed symmetrically with respect to the plane of symmetry of the airframe 10. In one embodiment, the third tilt rotor 43 and the fourth tilt rotor 44 of the tail fin 30 on the rear side of the main wing 20 of the vertical take-off and landing aircraft are fully tilting tilt rotors, and the first tilt rotor 41 and the second tilt rotor 42 on the front side of the main wing 20 are partially tilting tilt rotors. In a vertical take-off state, the first tilt rotor 41, the second tilt rotor 42, the third tilt rotor 43, and the fourth tilt rotor 44 all tilt upward to vertical take-off and landing positions, and are approximately centrosymmetric with each other, with each pair corresponding to the center of gravity of the vertical take-off and landing aircraft. The four outer fixed rotors are nearly centrosymmetric with each other, two for each rotor, about the center of gravity of the VTOL. This layout also has the advantages of the VTOL shown in Figure 2. Those skilled in the art will appreciate that, if mounting conditions permit, all tilt rotors may be configured as fully tilting tilt rotors.

[0037] Referring to Figures 29 to 31, the present invention also provides a vertical take-off and landing aircraft. The difference between this vertical take-off and landing aircraft and the vertical take-off and landing aircraft of Figure 2 is that the tail 30 of the vertical take-off and landing aircraft is a π-shaped tail, and the third and fourth tilt rotors of the tail are attached to both sides of the horizontal stabilizer of the π-shaped tail and are configured to tilt downward to the vertical take-off and landing position. The third and fourth tilt rotors may be fully tilted or partially tilted. In this embodiment, the third and fourth tilt rotors are fully tilted. In vertical take-off, the four inner tilt rotors in this solution are also nearly centrosymmetric with each other, with two corresponding rotors, about the center of gravity of the vertical take-off and landing aircraft. The four outer fixed rotors are also nearly centrosymmetric with each other, with two corresponding rotors, about the center of gravity of the vertical take-off and landing aircraft. This layout also has the advantages of the vertical take-off and landing aircraft of Figure 2.

[0038] In one embodiment of the present invention, each fixed rotor includes a folding rotor (not shown) and a fixed rotor drive unit (not shown). The fixed rotor drive unit in the present invention may be a motor or a combination of a motor and a reducer. In this embodiment, the folding rotor includes a fixed blade (not shown) and a floating blade (not shown). When the aircraft is in a hovering phase, the fixed rotor drive unit drives the fixed blade and the floating blade to rotate in a cross shape. When the aircraft is in a horizontal cruise phase, the fixed rotor drive unit stops operating, and the fixed blade and the floating blade close to form a cross shape along the airflow, with the extension direction of each fixed blade and the floating blade aligned with the aircraft's flight direction. This installation method reduces resistance during cruise. Note that in the present invention, the fixed blades and floating blades rotate in a cross shape during rotation and fold when stopped can be realized using any suitable conventional folding rotor configuration, and will not be further described here. Of course, those skilled in the art will appreciate that not all fixed rotors in the present invention need adopt the folding blade configuration if no desirable effect is considered.

[0039] The present invention further provides a control method for the above-mentioned vertical take-off and landing aircraft, the control method including the following transition process from vertical take-off to horizontal flight and / or transition process from horizontal flight to vertical landing: The transition process from vertical takeoff to horizontal flight is According to the forward flight command, the power system tilts the four inner tilt rotors forward; and setting the tilt speed of the four tilt rotors and the thrust distribution between the four tilt rotors and the four fixed rotors in accordance with a climb command, thereby controlling the climb speed and climb gradient of the takeoff and landing aircraft; The transition process from horizontal flight to vertical landing is a powered system tilting the four tilt rotors upward to a vertical takeoff and landing position according to a speed command; and setting the tilt speed of the four tilt rotors and the thrust distribution between the four tilt rotors and the four fixed rotors in accordance with a descent command, thereby controlling the descent speed and descent gradient of the vertical take-off and landing aircraft.

[0040] An embodiment of the control method of the present invention further includes the following control process when the aircraft accidentally enters a spin or stall and / or when a strong crosswind is encountered: The control process for the accidental spin or stall includes activating the four fixed rotors to assist attitude control and recover from the spin or stall. A spin is a continuous, automatic rotational motion that occurs after an aircraft's angle of attack exceeds a critical angle of attack. In a spin, the aircraft rapidly descends while rotating along a small-radius spiral trajectory, simultaneously rotating continuously around three axes: the roll axis, pitch axis, and yaw axis. A stall is a phenomenon in which the lift coefficient decreases as the angle of attack of the main wing of an aircraft (mainly an airplane) increases after the angle of attack exceeds a certain critical value. During a stall, the aircraft descends uncontrollably, sways violently, the engine vibrates, and the pilot notices an abnormality in the aircraft's control.

[0041] The control process when encountering a strong crosswind involves using thrust differentials of the four tilt rotors to assist yaw control and resist the crosswind when wind speed exceeds a set threshold.

[0042] Of course, the control method of the present invention can also include more control processes. Referring to Figure 32, the following provides a control method using four fixed rotors and four tilt rotors as an example. The method includes: Start the four tilt rotors and four fixed rotors to check the system status → If the system status is normal, issue a takeoff command → Continue rotating the four fixed rotors and four tilt rotors in the vertical takeoff and landing position until the aircraft leaves the ground and ascends vertically to the set altitude → Issue a forward flight command → According to the forward flight command, automatically control the four inner tilt rotors to tilt forward → According to the climb command, automatically adjust the tilt speed of the four tilt rotors and the thrust distribution between the four tilt rotors and the four fixed rotors and controls the ascent speed and ascent gradient until the transition from vertical takeoff to horizontal flight is completed → issues a command to transition from horizontal flight to vertical landing → automatically tilts the four inner tilt rotors upward in accordance with the command to transition from horizontal flight to vertical landing → automatically sets the tilt speed of the four tilt rotors and the thrust distribution between the four tilt rotors and the four fixed rotors in accordance with the command to descent, and controls the descent speed and descent gradient → the transition from horizontal flight to vertical descent is completed and the vertical descent begins → landing is completed → the power system is turned off.

[0043] The occurrence of an aircraft spin or stall during level flight may further include a control process for when the aircraft erroneously enters a spin or stall, wherein the control process for when the aircraft erroneously enters a spin or stall includes activating the four fixed rotors to assist attitude control to recover from the spin or stall condition.

[0044] When a strong crosswind with a wind speed exceeding a set threshold is encountered, the control process for when a crosswind is encountered can further include a control process for when a crosswind is encountered that includes assisting yaw control to resist the crosswind by thrust differentials of the four tilt rotors when the wind speed exceeds a set threshold.

[0045] Taking an electric vertical take-off and landing aircraft with four fixed rotors and four tilt rotors as an example, the vertical take-off and landing aircraft of the present invention has the following advantages: 1) During the transition process, attitude adjustment can be performed using four fixed rotors and four tilt rotors together, or pitch control can be achieved by differential thrust between the front and rear fixed rotors and roll control by differential thrust between the left and right fixed rotors using only four fixed rotors.Furthermore, adding independent asymmetric three-axis channel control ensures functional redundancy, which not only improves safety but also contributes to simplifying the control algorithm. 2) If any single rotor fails during level flight, the additional yaw moment can be balanced via the rudder to maximize the remaining power and maintain high performance after a single rotor failure, and in extreme cases, flight can continue even after two or three rotors fail. 3) In the event of abnormal situations such as control surface control failure, stall, or spin during horizontal flight, the fixed rotor can be used to recover compared to the full tilt configuration and forward half tilt configuration (the symmetrically arranged fixed rotor can achieve control of six rotation vectors). This inherits the advantages of the composite wing and improves the safety of the horizontal flight process (especially when altitude margin is insufficient). 4) In the event of a complete failure of the tilt rotor's operating function or a complete loss of tilt rotor thrust, a "controlled emergency landing" can be achieved via the fixed rotor, improving safety. 5) In the event of a complete loss of power system energy during hovering or transition, the collective pitch of the inner tilt rotor can be adjusted to achieve a "controllable emergency landing" (capable of completing control of six rotation vectors), achieving helicopter-like autorotation gliding capabilities. 6) The four inner tilt rotors reduce the frontal area of ​​the fixed rotors compared to a configuration with four tilt rotors forward of the main wing, which is advantageous for reducing drag. 7) Compared to a fully tilting configuration, the slope of ascent or descent can be adjusted by adjusting the thrust distribution between the four inner tilt rotors and the four outer fixed propellers, which is advantageous for takeoff and landing in complex urban environments.

[0046] As described above, the present invention not only combines the advantages of composite wing, full tilt layout, and partial tilt layout through a special layout format, but also widens the transition corridor through this layout method, while at the same time reducing the difficulty of research and development of vertical take-off and landing aircraft and contributing to the rapid progress of the product commercialization process. Therefore, the present invention effectively overcomes some practical problems in the prior art and has great utility value and practical significance.

[0047] The above examples are illustrative of the principles and effects of the present invention, but are not intended to limit the present invention. Those skilled in the art may modify or change the above examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention are still intended to be included in the scope of the claims of the present invention. [Explanation of symbols]

[0048] 10 aircraft 11 Vertical symmetry plane 12 Vertical plane 20 Main wing 30 tail fin 41 Tiltrotor No. 1 411 Third Arm 42 Second tilt rotor 421 4th Arm 43 Third Tiltrotor 431 5th Arm 44 4th tilt rotor 441 6th Arm 401 Tilt Propeller 51 First fixed rotor 511 First Arm 52 Second fixed rotor 521 Second Arm 53 Third fixed rotor 54 4th fixed rotor 60 First branch arm 70 First Circumference 80 Second Circumference 90 Second branch arm.

Claims

1. 1. A vertical take-off and landing aircraft, The aircraft has wings symmetrically placed on both sides, four tilt rotors, each attached to the front and rear of the main wings on both sides, with two corresponding positions, rotation directions, and attachment angles that are symmetrical with respect to the longitudinal symmetry plane of the fuselage, with the distance between the two tilt rotors on the front side of the main wings being A, the distance between the two tilt rotors on the rear side of the main wings being B, and the deviation between A and B being 0.2*(A+B) / 2 or less; four fixed rotors, the four fixed rotors being attached to the outside of the tilt rotors on both sides of the fuselage, respectively, and located on the front and rear sides of the main wings, with two corresponding positions, rotation directions, and attachment angles that are symmetrical with respect to the vertical symmetry plane, the distance between the two fixed rotors on the front side of the main wings being C, the distance between the two fixed rotors on the rear side of the main wings being D, and the deviation between C and D being 0.05*(C+D) / 2 or less; a vertical take-off and landing aircraft, wherein in a vertical take-off state, projections of the four tilt rotors on a horizontal plane correspond to each other in pairs and are centrally symmetrical about the center of gravity of the vertical take-off and landing aircraft within a first set range, their positions being symmetrical about a vertical plane that passes through the center of gravity and is perpendicular to the vertical symmetry plane, a longitudinal interval between the horizontal projections of the tilt rotors is M, and the first set range is such that a longitudinal deviation between an intersection of a line connecting diagonals of the horizontal projections of the four tilt rotors and the horizontal projection of the center of gravity is 0.1*M or less, and a vertical take-off and landing aircraft, wherein projections of the four fixed rotors on a horizontal plane correspond to each other in pairs and are centrally symmetrical about the center of gravity within a second set range, their positions being symmetrical about the vertical plane, a longitudinal interval between the lines connecting diagonals of the horizontal projections of the four fixed rotors is N, and the second set range is such that a longitudinal deviation between an intersection of a line connecting diagonals of the horizontal projections of the four fixed rotors and the horizontal projection of the center of gravity is 0.1*N or less.

2. 2. The vertical take-off and landing aircraft according to claim 1, wherein the tilt rotors on the front and / or rear sides of the main wing are attached to the main wing via arms.

3. 2. The vertical take-off and landing aircraft according to claim 1, wherein the tilt rotors on the front and / or rear sides of the main wing are attached to the fuselage via branched arms.

4. 2. The vertical take-off and landing aircraft according to claim 1, wherein the tilt rotor on the front side of the main wing is attached to the main wing via an arm, and the tilt rotor on the rear side of the main wing is attached to the airframe via a branched arm.

5. 2. The vertical take-off and landing aircraft according to claim 1, wherein a tail is provided at a tail section of the aircraft, and the tail is one of a V-tail, a Y-tail, an H-tail, an X-tail, a T-tail, and a U-tail.

6. 6. The vertical take-off and landing aircraft of claim 5, wherein the two tilt rotors are mounted on the tail and provide forward thrust as the aircraft moves forward, and can be tilted upward to provide vertical thrust when the aircraft is in a vertical take-off condition.

7. 7. The vertical take-off and landing aircraft according to claim 6, wherein the tail is a V-tail, and the two tilt rotors on the rear side of the main wings are attached to wing tips on both sides above the tail, respectively.

8. 2. The vertical take-off and landing aircraft according to claim 1, wherein an arm is attached to each of the main wings on both sides of the aircraft, and the four fixed rotors are symmetrically attached to the arms on both sides of the aircraft, and are respectively located on the front and rear sides of the main wings.

9. 9. A control method for a vertical take-off and landing aircraft according to claim 1, comprising a transition process from vertical take-off to horizontal flight and / or a transition process from horizontal flight to vertical landing, The transition process from vertical takeoff to horizontal flight is a power system tilting the four tilt rotors forward according to a forward flight command; automatically setting the thrust distribution between the four inner tilt rotors and the four outer fixed rotors and the tilt speed of the four inner tilt rotors according to a climb command, and controlling the speed and climb gradient; The transition process from horizontal flight to vertical landing is a power system tilting the four tilt rotors upward to a vertical takeoff and landing position according to a speed command; and automatically setting the thrust distribution between the four inner tilt rotors and the four outer fixed rotors and the tilt speed of the four inner tilt rotors in accordance with a descent command, and controlling the speed and descent gradient.

10. Further including a control process when the aircraft accidentally enters a spin or stall and / or a control process when a crosswind is encountered, the control process in the event of an erroneous spin or stall includes actuating the four outer fixed rotors to assist attitude control to recover from the spin or stall condition; 10. The control method of claim 9, wherein the control process when encountering a crosswind includes using thrust differentials of the four tilt rotors to assist yaw control to resist the crosswind when wind speed exceeds a set threshold.

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