A vertical take-off and landing aircraft and method of take-off and landing thereof

Abstract

This application discloses a vertical takeoff and landing (VTOL) aircraft and its takeoff and landing methods. The VTOL aircraft includes an aircraft body and a propeller-driven propulsion system. The aircraft body includes a fuselage, wings, and a tail boom. The tail boom is located near the tail of the fuselage and is used to support the aircraft body when parked on the ground or during rollover on the ground. The propeller-driven propulsion system includes a propeller and a tilting mechanism. The propeller is connected to the aircraft body via the tilting mechanism to change the angle between the propeller's thrust line and the fuselage axis. The point of application of the lift force exerted by the propeller on the aircraft body is closer to the nose of the fuselage than the aircraft's center of gravity. The lift force exerted by the propeller on the aircraft body causes the aircraft body to roll around the contact point of the tail boom to switch between a horizontal parking attitude and a vertical takeoff and landing attitude.

Description

Technical Field

[0001] This application relates to the field of aircraft technology, and in particular to a vertical take-off and landing aircraft and its take-off and landing methods. Background Technology

[0002] Vertical takeoff and landing (VTOL) aircraft can take off and land without a runway, and have broad application prospects in complex terrain warfare, urban air traffic, and emergency rescue. Aircraft possessing both VTOL and high-speed horizontal flight capabilities represent one of the important development directions in the current aviation technology field. Currently, there are two main technical approaches to achieving both VTOL and high-speed cruise capabilities.

[0003] One type is the tiltrotor vertical takeoff and landing (VTOL) aircraft, represented by Bell Helicopter's V-22 Osprey. This type of aircraft, based on a fixed-wing aircraft, has tiltable engines and rotors at the wingtips. By adjusting the rotor's thrust direction through a tilting mechanism, it achieves switching between vertical takeoff and landing and horizontal flight. Its advantages include a low center of gravity, making it less prone to tipping over during crosswinds or takeoff and landing, and better adaptability to various takeoff and landing environments. However, this type of aircraft has the following technical drawbacks: First, the tilt mechanism must not only realize the conversion function between vertical takeoff and landing and level flight, but also act as the control mechanism for the aircraft's pitch and yaw. This places extremely high demands on the strength and vibration response of the mechanism, resulting in a complex, bulky, and costly tilt mechanism structure. Second, this type of aircraft is very sensitive to the position of its center of gravity along the length of the fuselage. The center of gravity can only be adjusted within a very small deviation range near the intersection of the line connecting the two tilt axes and the longitudinal axis of the fuselage, which severely restricts the loading position and space of the cargo hold. Third, during the transition from vertical takeoff and landing to level flight, the aerodynamic interference between the rotor slipstream and the wing is quite severe, making control complex and bringing reliability risks.

[0004] Another type is the tail-sit vertical takeoff and landing (VTOL) aircraft, represented by Sikorsky's Nomad series. This type of aircraft uses a fixed-mounted engine and does not require rotor tilting, switching between vertical takeoff and landing and horizontal flight through changes in the overall fuselage attitude. Its advantage is its simple structure, avoiding the complexity associated with tilting mechanisms. However, this type of aircraft has the following technical drawbacks: First, in both VTOL and parking states, the tail-sit aircraft has a vertically positioned fuselage with a large frontal area, making it prone to tipping over in crosswinds, resulting in poor adaptability to takeoff and landing environments and limited usage scenarios. Second, to lower the center of gravity and improve parking stability, the fuselage is designed with a short and stubby configuration, leading to higher aerodynamic drag and limiting the upper speed limit. Third, this type of aircraft uses a slipstream control system, where the rotor slipstream blows across the wing control surfaces to generate control torque. Due to the low center of gravity and wing chord limitations, the control force generated by the control surfaces is very short from the aircraft's center of gravity pitch arm, limiting pitch control effectiveness and maneuverability.

[0005] Therefore, it is necessary to propose a technical solution to overcome the shortcomings of existing technologies. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, this application provides a vertical take-off and landing aircraft and its take-off and landing method. While retaining the advantages of the two types of vertical take-off and landing aircraft mentioned above, it overcomes at least one technical problem, such as the complex and cumbersome tilt mechanism, sensitive center of gravity, complex control, and the poor adaptability of tail-sitting aircraft to the take-off and landing environment, slow flight speed, and insufficient maneuverability.

[0007] This application is achieved through the following technical solution: a vertical takeoff and landing aircraft, comprising: The aircraft body includes a fuselage, wings and a tail boom, the tail boom being located near the tail of the fuselage and used to support the aircraft body when the aircraft is parked on the ground or when it is flipping on the ground. A propeller-driven propulsion system, comprising a propeller and a tilting mechanism, wherein the propeller is connected to the aircraft body via the tilting mechanism to change the angle between the propeller's thrust line and the fuselage axis; The point at which the propeller exerts its lift force on the aircraft body is closer to the nose of the fuselage than the center of gravity of the aircraft. The lift force exerted by the propeller on the aircraft body causes the aircraft body to rotate around the contact point of the tail boom to switch between a horizontal parking posture and a vertical take-off and landing posture.

[0008] As a further improved technical solution, the tilting mechanism is configured such that the angle between the thrust line of the propeller and the fuselage axis is adjustable within the range of -10° to 100°.

[0009] As a further improved technical solution, the tilting mechanism includes a fixed part and a rotating part pivotally connected to the fixed part. The fixed part is mounted on the aircraft body, and the rotating part is connected to the propeller. The propeller adjusts the angle between itself and the fuselage axis through the pivoting motion of the rotating part relative to the fixed part.

[0010] As a further improved technical solution, the propeller is connected to the front end of the wing through the rotating part and the fixed part of the tilting mechanism.

[0011] As a further improved technical solution, during the process of the aircraft body rotating around the contact point of the tail boom to switch between a horizontal parking attitude and a vertical take-off and landing attitude, the propeller is controlled so that its thrust line always remains perpendicular to the ground to avoid horizontal dragging of the tail boom on the ground.

[0012] As a further improved technical solution, the tilting mechanism is configured to maintain the angle between the propeller and the fuselage axis unchanged during the flight of the aircraft after it leaves the ground, so as not to participate in the flight attitude control of the aircraft.

[0013] As a further improved technical solution, the aircraft also includes a support rod, which, when the aircraft is parked on the ground, serves as a front support member and together with the tail support to support the aircraft body.

[0014] As a further improved technical solution, the support rod is retractable and is in a retracted state during the flight of the aircraft to reduce flight resistance.

[0015] As a further improved technical solution, the support rod is linked to the propeller, and when the angle between the thrust line of the propeller and the fuselage axis approaches zero, the support rod is in a retracted state that is nearly parallel to the fuselage axis.

[0016] As a further improved technical solution, the propeller power system includes a left propeller power unit and a right propeller power unit disposed on the left and right wings. The left propeller power unit and the right propeller power unit are configured such that their propellers can rotate in opposite directions to counteract the counter torque.

[0017] As a further improved technical solution, the rotational speed or pitch of the propellers in the left propeller power unit and the right propeller power unit are independently adjustable.

[0018] As a further improved technical solution, the wing includes an aileron located behind the propeller, and the fuselage also includes a vertical stabilizer and a horizontal stabilizer located at the tail of the fuselage, with the tail boom positioned further back than the vertical stabilizer and the horizontal stabilizer.

[0019] This application also achieves this through the following technical solution: a takeoff method for a vertical takeoff and landing (VTOL) aircraft, used for the VTOL aircraft as described above, the takeoff method comprising: The aircraft is placed on the ground in a horizontal parking position; The propeller power system is activated to generate lift force to lift the nose of the aircraft, and the angle between the thrust line of the propeller and the fuselage axis is changed by the tilting mechanism so that the thrust line of the propeller is perpendicular to the ground, thereby driving the aircraft body to flip from a horizontal parking posture to a vertical take-off and landing posture around the contact point of the tail boom. Apply a lift force sufficient to lift the aircraft off the ground to drive it to lift off the ground and ascend vertically.

[0020] This application also achieves this through the following technical solution: a landing method for a vertical takeoff and landing (VTOL) aircraft, used for the VTOL aircraft as described above, the landing method comprising: In mid-air, the aircraft is converted to a vertical flight attitude and controlled to descend vertically until the tail boom touches the ground; Adjust the lift generated by the propeller power system, and change the angle between the propeller's thrust line and the fuselage axis through the tilting mechanism so that the propeller's thrust line remains perpendicular to the ground, thereby driving the aircraft body to flip from a vertical take-off and landing attitude to a horizontal parking attitude around the contact point of the tail boom.

[0021] The vertical takeoff and landing (VTOL) aircraft provided in this application achieves switching between horizontal parking and vertical takeoff and landing attitudes by mounting a tilting mechanism on the aircraft body to change the angle between the propeller thrust line and the fuselage axis, and by placing the propeller lift force application point in front of the aircraft's center of gravity. This allows the propeller lift force to drive the aircraft body to rotate around the tail boom contact point. Compared to in-flight tiltrotor designs, the tilting process in this application is completed on the ground, and the tilting mechanism does not need to participate in the flight attitude control after the aircraft leaves the ground. Therefore, the structural complexity, weight, and manufacturing cost of the tilting mechanism are significantly reduced. This design significantly reduces drag while avoiding aerodynamic interference and center-of-gravity sensitivity issues during in-flight tilting. Compared to tail-sitting vertical takeoff and landing (VTOL) systems, the aircraft in this application maintains a horizontal attitude when parked, resulting in a low center of gravity, small frontal area, and reduced risk of tipping over in crosswinds. This significantly improves adaptability to takeoff and landing environments. Furthermore, the aircraft can adopt a conventional low-drag aerodynamic layout, free from the limitations of a tail-sitting short and stubby fuselage, which is beneficial for increasing flight speed and maneuverability. In addition, the tail boom remains in contact with the ground throughout the tilting process, providing physical support for the aircraft and further enhancing its stability and controllability during tilting. Attached Figure Description

[0022] Figure 1 This is a structural schematic diagram of the vertical takeoff and landing aircraft of this application.

[0023] Figure 2 yes Figure 1 A magnified view of a portion of point A in the middle.

[0024] Figure 3 This is a structural schematic diagram of the vertical takeoff and landing aircraft from another perspective.

[0025] Figure 4 This is a schematic diagram of the takeoff process of the vertical takeoff and landing aircraft of this application.

[0026] The attached figures are labeled as follows: 1. Aircraft body; 11. Fuselage; 12. Wing; 121. Aileron; 13. Tail boom; 14. Vertical tail; 15. Horizontal tail; 2. Propeller power system; 21. Propeller; 22. Tilting mechanism; 221. Fixed part; 222. Rotating part; 23. Power unit; 24. Support rod. Detailed Implementation

[0027] To provide a clearer understanding of the technical features, objectives, and effects of this application, the specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0029] like Figures 1 to 3As shown, this application provides a vertical takeoff and landing (VTOL) aircraft, which includes an aircraft body 1 and a propeller-driven propulsion system 2. The aircraft body 1 adopts a conventional aerodynamic layout, including a fuselage 11 and wings 12. The wings 12 are arranged at the front of the fuselage 11, and the tail of the fuselage 11 is provided with a vertical stabilizer 14 and a horizontal stabilizer 15. The aircraft also includes ailerons 121, elevators, rudders, and other control surfaces for flight control. The wings 12 can adopt a conventional fixed-wing layout, with the left and right wings 12 symmetrically arranged on both sides of the fuselage 11. The vertical stabilizer 14 is provided with a rudder, and the horizontal stabilizer 15 is provided with an elevator. These control surfaces are used to control the heading and pitch attitude of the aircraft when it is in horizontal cruise flight. Furthermore, the aircraft body 1 also includes a tail boom 13, which is located near the tail of the fuselage 11 and is used to support the aircraft body 1 when the aircraft is parked on the ground or during rollover on the ground. The tail boom 13 can adopt a streamlined design to reduce air resistance during horizontal cruise flight. The tail boom 13 is positioned further rearward than the vertical stabilizer 14 and horizontal stabilizer 15, meaning it is located at the very rear of the aircraft body 1. When the aircraft is in a vertical takeoff and landing attitude, the end of the tail boom 13 serves as the contact point between the aircraft and the ground. In some embodiments, the tail boom 13 has a tail cone-shaped structure; furthermore, the number of tail booms 13 can be one, two, or more, and this application does not limit the specific shape and number of tail booms 13. During the process of the aircraft flipping from a horizontal parking attitude to a vertical takeoff and landing attitude, the contact point of the tail boom 13 remains in contact with the ground, providing a stable pivot point for the aircraft. With this configuration, the aircraft has physical support throughout the tilting process, significantly enhancing the stability and controllability of the tilting process and avoiding the risk of loss of control due to hovering tilting. The aircraft body 1 adopts a conventional low-drag aerodynamic layout, unrestricted by the short, stubby fuselage of a tail-sitting design, which is beneficial for improving flight speed and maneuverability. Meanwhile, the aircraft body 1 is in a horizontal position when parked, with a low center of gravity and a small frontal area, making it less prone to overturning in crosswind environments, and significantly improving its adaptability to take-off and landing environments.

[0030] like Figure 2As shown, the propeller-driven propulsion system 2 includes a propeller 21 and a tilting mechanism 22. The propeller 21 is connected to the aircraft body 1 via the tilting mechanism 22, enabling the adjustment of the angle between the propeller 21's thrust line and the fuselage 11 axis. Specifically, the tilting mechanism 22 includes a fixed part 221 and a rotating part 222 pivotally connected to the fixed part 221. The fixed part 221 is mounted on the aircraft body 1, specifically at the leading edge of the wing 12. The rotating part 222 is connected to the propeller 21, and the angle between the propeller 21 and the fuselage 11 axis is adjusted by the pivoting motion of the rotating part 222 relative to the fixed part 221. The tilting mechanism 22 can be driven by a motor, hydraulic cylinder, pneumatic cylinder, or similar drive device to pivot the rotating part 222 relative to the fixed part 221. With this configuration, the propeller 21 can adjust its thrust line direction according to the needs of different stages of the aircraft, thus accommodating the different power direction requirements of various operating modes such as ground tilting, vertical takeoff and landing, and horizontal cruise. The tilt mechanism 22 is configured to allow the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 to be adjustable within the range of -10° to 100°. Specifically, 0° is defined as the thrust line of the propeller 21 being horizontally forward and parallel to the axis of the fuselage 11; a positive angle is defined as the thrust line of the propeller 21 tilting upward relative to the axis of the fuselage 11, and a negative angle is defined as tilting downward. Driven by the tilt mechanism 22, the propeller 21 can arbitrarily adjust the angle between its thrust line and the axis of the fuselage 11 within the range of -10° to 100° to adapt to the power requirements of the aircraft in different flight phases and ground attitudes. This angle range allows the propeller 21 to provide thrust in a near-vertical upward direction to lift the nose when stationary on the ground, and to provide thrust in a horizontally forward direction during level cruise, while also enabling smooth angle switching during transitions. With this configuration, the tilting mechanism 22 only needs to tilt the propeller 21 on the ground, without having to withstand complex aerodynamic loads and perform high-frequency responses in the air. Therefore, the tilting mechanism 22 can adopt a simpler structure and lower strength requirements, which significantly reduces the structural complexity, weight and manufacturing cost of the tilting mechanism.

[0031] In this application, the point of application of the lift force exerted by the propeller 21 on the aircraft body 1 is closer to the nose of the fuselage 11 than the center of gravity of the aircraft. In other words, the line of action of the lift force generated by the propeller 21 is located in front of the center of gravity of the aircraft in the horizontal direction. This configuration allows the lift force exerted by the propeller 21 on the aircraft body 1 to drive the aircraft body 1 to flip around the contact point of the tail boom 13, thereby switching the aircraft body 1 between a horizontal parking attitude and a vertical take-off and landing attitude. Specifically, when the aircraft is placed on the ground in a horizontal parking attitude, the contact point of the tail boom 13 is in contact with the ground, serving as the fulcrum for the aircraft to flip. Since the point of application of the lift force of the propeller 21 is located in front of the center of gravity of the aircraft, the thrust generated by the propeller 21 creates a pitching moment on the aircraft, driving the nose to lift up, and the aircraft body 1 to flip around the contact point of the tail boom 13. With this setting, the aircraft can achieve attitude switching without a complex tilting mechanism, simplifying the structure, reducing weight, and lowering costs. Meanwhile, because the point of force application is located in front of the center of gravity, the aircraft has pitch static stability in a vertical hovering state, which reduces the difficulty of vertical take-off and landing control.

[0032] During the process of the aircraft body 1 flipping around the contact point of the tail boom 13 to switch between a horizontal parking attitude and a vertical takeoff and landing attitude, the propeller 21 is controlled so that its thrust line remains perpendicular to the ground to avoid generating a component force along the axis of the fuselage 11. Specifically, as the aircraft body 1 flips around the contact point of the tail boom 13, the angle between the fuselage 11 and the ground gradually increases, and the tilting mechanism 22 accordingly tilts the propeller 21 relative to the fuselage 11 to maintain the direction of the propeller 21's thrust line perpendicular to the ground. Through this control strategy, it is ensured that the aircraft is only subjected to the overturning torque during the tilting process, and the thrust of the propeller 21 does not generate a horizontal component force along the axis of the fuselage 11, thereby preventing unnecessary horizontal sliding of the aircraft on the ground, and the contact point of the tail boom 13 does not slide relative to the ground, improving the stability and controllability of the tilting process. This feature allows the aircraft to safely complete the tilting even on ground with a certain slope, significantly improving the aircraft's adaptability to takeoff and landing environments. The tilt mechanism 22 is configured to maintain a constant angle between the propeller 21 and the fuselage 11 axis during the aircraft's flight after takeoff, thus not participating in the aircraft's attitude control. Specifically, the tilt mechanism 22 only operates during ground tilting, adjusting the angle between the propeller 21's thrust line and the fuselage 11 axis to achieve gradual nose-up and down. Once the aircraft enters the vertical ascent phase after takeoff, the tilt mechanism 22 maintains its current tilt angle, and the aircraft's attitude control is entirely handled by aerodynamic control surfaces such as the ailerons 121, elevators, rudders, and the differential thrust of the propeller 21. The tilt mechanism 22 does not participate in pitch, roll, or yaw control after takeoff, significantly reducing its design requirements and manufacturing costs, while also improving flight control reliability. Since the tilt mechanism 22 does not need to withstand complex aerodynamic loads or perform high-frequency responses in the air, a simpler structure and lower strength requirements can be adopted, further reducing costs. At the same time, it also avoids aerodynamic interference and center of gravity sensitivity issues during the in-flight tilting process.

[0033] like Figure 1 and Figure 2As shown, the aircraft also includes a support rod 24, which, when the aircraft is parked on the ground, serves as a front support member and, together with the tail boom 13, supports the aircraft body 1. Specifically, the support rod 24 is located at the front of the wing 12 and is connected to the rotating part 222 of the tilting mechanism 22. When the aircraft is placed on the ground in a horizontal parking posture, the lower end of the support rod 24 contacts the ground, forming a stable support for the aircraft body 1 together with the contact point of the tail boom 13. The support rod 24 is linked to the propeller 21. When the tilting mechanism 22 drives the propeller 21 to tilt, the support rod 24 moves synchronously with the propeller 21. Specifically, one end of the support rod 24 is fixedly connected to the rotating part 222 of the tilting mechanism 22, and the other end is a free end that contacts the ground when the aircraft is parked. When the rotating part 222 pivots relative to the fixed part 221, the support rod 24 moves together with the rotating part 222. When the angle between the thrust line of propeller 21 and the axis of fuselage 11 approaches zero, that is, when propeller 21 is in a horizontal forward position, support rod 24 is in a retracted state that is nearly parallel to the axis of fuselage 11. This linkage design eliminates the need for a separate retraction mechanism for support rod 24, simplifying the aircraft's structure and reducing its weight. Support rod 24 is retractable and is in a retracted state during flight to reduce drag. Specifically, after the aircraft completes ground tilting, enters vertical takeoff, and leaves the ground, tilting mechanism 22 drives propeller 21 to gradually tilt to a position where the angle between the thrust line and the axis of fuselage 11 approaches zero. At this time, support rod 24 simultaneously retracts to a state that is nearly parallel to the axis of fuselage 11, attaching to the front of wing 12 or both sides of fuselage 11 to reduce air resistance during horizontal cruise flight. The approach to zero includes cases where the included angle is zero and cases with a small included angle. For example, in some designs, when the aircraft is in level flight, there is a small pre-set installation angle between the thrust line of the propeller 21 and the axis of the fuselage 11 to compensate for the pitching moment of the entire aircraft. In this way, when the propeller 21 is tilted to the extreme position, there is still a small included angle between it and the axis of the fuselage 11. The support rod 24 can adopt a streamlined cross-section design to further reduce flight drag. With this setting, the support rod 24 provides stable front support during ground parking and tilting, and automatically retracts to reduce drag during flight, achieving a balance between support function and aerodynamic performance. As an alternative implementation, the support rod 24 can also be independently set without linkage with the propeller 21; in some embodiments, the support rod 24 can also be set on the fuselage 11, and it can also be stored in other ways, such as being stored in a groove opened under the fuselage 11. Its specific structure can be a support wheel or other forms.

[0034] The propeller propulsion system 2 includes a left propeller propulsion unit and a right propeller propulsion unit mounted on the left and right wings 12. Each propeller propulsion unit includes its own propeller 21 and power unit 23. The left and right propeller propulsion units are configured such that their propellers 21 rotate in opposite directions to counteract torque. Specifically, when the aircraft is in a vertical hovering state, one propeller 21 rotates clockwise, while the other rotates counterclockwise. The counter-torque generated by the two propellers cancels each other out, resulting in a zero-torque state for the entire aircraft, which is beneficial for attitude stability. This configuration eliminates the need for additional torque compensation devices to achieve directional stability during hovering, simplifying the structure and reducing weight. The rotational speed or pitch of the propellers 21 in the left and right propeller propulsion units is independently adjustable. By independently adjusting the rotational speed or pitch of the left and right propellers 21, differential thrust can be generated, thereby controlling the yaw attitude of the aircraft. For example, when the aircraft is in a vertical hovering state, increasing the thrust of the left propeller 21 while decreasing the thrust of the right propeller 21 generates a yaw moment, driving the aircraft to rotate around its vertical axis. The differential thrust can originate from speed regulation, achieved by controlling the output speed of the power unit 23, or from pitch regulation, for example, by controlling the pitch angle of the variable-pitch propeller in an embodiment using a variable-pitch propeller. With this configuration, yaw control in the hovering state does not require additional control surfaces or thrusters, simplifying the system structure and improving control efficiency. The power unit 23 drives the propeller 21 to rotate and generate thrust. The power unit 23 can be an electric motor, a fuel engine such as a diesel engine or gasoline engine, or a hybrid power system.

[0035] The wing 12 includes ailerons 121 located behind the propeller 21. When the aircraft is in a vertical hovering state, the propeller 21 generates a high-speed rearward airflow that blows over the ailerons 121. By controlling the deflection of the ailerons 121, this high-speed airflow can be used to generate additional aerodynamic control force. The ailerons 121 can be conventionally hinged to the trailing edge of the wing 12, and their deflection angle can be controlled by servos or similar drive mechanisms. Specifically, when both ailerons 121 deflect in the same direction, the pitch attitude of the aircraft can be controlled; when both ailerons 121 deflect in opposite directions, the roll attitude of the aircraft can be controlled. This slipstream control method is particularly effective in hovering states where the ground speed is zero or close to zero, compensating for the insufficient control effectiveness of conventional aerodynamic control surfaces at low speeds. With this configuration, the aircraft can achieve precise pitch and roll control in hovering states without the need for an additional attitude control system, simplifying the system structure and improving control reliability.

[0036] The following combination Figure 4 The ground tilting and working principle of the aircraft in this application are described in detail. Figure 4 This demonstrates the tilting process of an aircraft transitioning from a ground-based parking position to a vertical takeoff and landing position. For example... Figure 4 As shown in Figure (a), the aircraft is placed on the ground in a horizontal parking posture. At this time, the fuselage 11 is approximately horizontal, with its axis aligned with the X-axis. The support rods 24 and the tail boom 13 jointly support the aircraft body 1. The direction of the thrust line of the propeller 21 is indicated by the Z-axis, and the angle between it and the X-axis of the fuselage 11 is approximately 90°, meaning the thrust line of the propeller 21 is approximately vertically upward. The two side support rods 24 and the tail boom 13 form a three-point support configuration, providing stable parking support for the aircraft. In the parking state, the aircraft has a low center of gravity and a small frontal area, making it less prone to tipping over in crosswinds. Similar to the parking state of conventional fixed-wing aircraft, it exhibits good ground stability.

[0037] The propeller power system 2 is activated, and the propellers 21 on both sides rotate in a counter-rotating manner to eliminate counter-torque. The propellers 21 generate a combined pull force F. The tilting axis of the tilting mechanism 22, i.e., the pivot axis of the rotating part 222 relative to the fixed part 221, is the point where the combined pull force F is applied to the lift force on the aircraft body 1. Its horizontal distance from the aircraft's center of gravity is L1, and the horizontal projection distance from the contact point of the tail support 13 to the aircraft's center of gravity is L2. The total weight of the aircraft passing through its center of gravity is G, the combined supporting force of the ground on the left and right support rods 24 is D1, and the upward supporting force of the ground on the tail support 13 is D2. When the aircraft is parked, the force balance relationship is: D1 × L1 = D2 × L2, D1 + D2 = G. Therefore, D1 = G × L2 / (L1 + L2). When the combined pull force F of the propellers 21 is greater than D1, the nose of the aircraft can be pulled up. When the condition G > F > D1 = G × L2 / (L1 + L2) is met, the aircraft begins to pitch up and roll. During this process, the support rod 24 gradually detaches from the ground, while the tail boom 13 remains in contact with the ground, and the aircraft body 1 rolls around the contact point of the tail boom 13. With this configuration, the aircraft's tilting process is completed on the ground, eliminating the need for a complex in-flight tilting mechanism, simplifying the structure, and reducing the difficulty of control.

[0038] During the process of raising the nose of the aircraft, the tilting mechanism 22 continuously adjusts the angle between the thrust line of the propeller 21 and the axis of the fuselage 11, that is, the angle between the Z-line and the X-line, so that the thrust line of the propeller 21 always remains perpendicular to the ground. Figure 4As shown in Figure (b), specifically, as the aircraft body 1 flips around the contact point of the tail boom 13, the angle between the fuselage 11 and the ground gradually increases. The tilting mechanism 22 correspondingly drives the propeller 21 to tilt relative to the fuselage 11, maintaining the thrust line of the propeller 21 perpendicular to the ground. This is to prevent the thrust of the propeller 21 from generating a horizontal component along the axis of the fuselage 11, thereby preventing unnecessary horizontal sliding of the aircraft on the ground. Through this control strategy, the aircraft is almost entirely subjected to a rollover torque during the tilting process, and the contact point of the tail boom 13 does not slide relative to the ground, improving the stability and controllability of the tilting process.

[0039] like Figure 4 As shown in Figure (c), when the aircraft's nose continues to pull up, making the fuselage 11 completely vertical, the aircraft's state is similar to that of a tail-sitting aircraft taking off. At this time, the aircraft is in a vertical takeoff and landing attitude, the contact point of the tail boom 13 is in contact with the ground, and the thrust line of the propeller 21 is perpendicular to the ground and upwards. In this state, the force balance relationship is F + D3 = G, where D3 is the upward support force exerted by the ground on the tail boom 13. In the vertical hovering state, the yaw attitude of the aircraft can be controlled by the differential force of the two propellers 21; using the ailerons 121 located behind the propellers 21, a slipstream control method is employed. The pitch attitude of the aircraft can be controlled by deflecting the ailerons 121 in the same direction, and the roll attitude can be controlled by deflecting them in opposite directions. In this state, the thrust plane of the propellers 21 is higher than the aircraft's center of gravity, and the aircraft itself is in a statically stable state in pitch and yaw, reducing the difficulty of subsequent vertical takeoff and landing control. With this setup, the aircraft has complete attitude control capabilities while hovering on the ground, preparing it for subsequent vertical takeoff.

[0040] Continue increasing the throttle until F > G, and the aircraft will lift off the ground and accelerate vertically upwards. As the aircraft continues to accelerate, when its vertical flight speed slightly exceeds its stall speed (assuming the stall speed is Vs and the vertical flight speed is Vc), generally speaking, when Vc > 1.2Vs, the aircraft enters the attitude transition phase, that is, it changes from vertical flight to horizontal flight. Figure 4 As shown in Figure (d), the elevator is used to control the pitch of the aircraft during attitude transitions. Since the aircraft has accumulated sufficient safe flight speed at this point, the elevator has sufficient control effectiveness. After the aircraft enters level cruise flight, the conventional ailerons, elevator, and rudder are used to easily control the aircraft.

[0041] The landing process is the reverse of the takeoff process, that is, from... Figure 4 The state shown in Figure (d) goes through the states shown in Figure (c) and (b) in sequence, and finally transforms into the state shown in Figure (a).

[0042] This application also provides a method for taking off and landing a vertical takeoff and landing (VTOL) aircraft. The takeoff method includes the following steps: placing the aircraft on the ground in a horizontal parking posture, at which point the fuselage 11 of the aircraft body 1 is approximately horizontal, the support rod 24 and tail boom 13 jointly support the aircraft body 1, the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 is approximately 90°, and the thrust line of the propeller 21 is approximately vertically upward. The propeller power system 2 is activated to generate lift force to raise the nose, and the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 is dynamically changed by the tilting mechanism 22 so that the thrust line of the propeller 21 remains perpendicular to the ground, thereby driving the aircraft body 1 to rotate from a horizontal parking posture to a vertical takeoff and landing posture around the contact point of the tail boom 13. Specifically, the propeller power systems 2 on both sides are activated, the propellers 21 on both sides rotate in opposite directions to eliminate counter-torque, gradually increasing the lift force of the propellers 21, the nose of the aircraft begins to lift, the support rod 24 leaves the ground, and the tail boom 13 remains in contact with the ground. The lift force is continuously increased, and in conjunction with the adjustment of the tilt mechanism 22, the aircraft body 1 continues to rotate around the contact point of the tail boom 13 until the fuselage 11 is completely vertical. Throughout the tilting process, the tilt mechanism 22 continuously adjusts the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 to ensure that the thrust line of the propeller 21 remains perpendicular to the ground. Then, a lift force sufficient to lift the aircraft off the ground is applied to drive it to lift off the ground and ascend vertically. Once the aircraft is in a vertical takeoff and landing attitude, the thrust of the propeller 21 is further increased so that the lift force F is greater than the total weight G of the aircraft, and the aircraft lifts off the ground and accelerates vertically. After vertical takeoff, the aircraft enters a transitional flight phase. When the vertical ascent speed of the aircraft exceeds a predetermined multiple of the aircraft's stall speed, the pitch attitude of the aircraft is controlled by the elevator to change the aircraft from a vertical attitude to a horizontal attitude, entering a horizontal cruise flight mode. This takeoff method allows the aircraft to tilt on the ground and then take off vertically in a tail-sitting manner, eliminating the need for a complex in-flight tilting process. Control is simple, reliable, and highly safe. Furthermore, because the aircraft only transitions to horizontal flight after ascending vertically to speeds exceeding the stall speed, the entire transition occurs within the aerodynamically safe zone, avoiding the risk of stall.

[0043] The landing method includes the following steps: In the air, the aircraft is converted to a vertical flight attitude, and the aircraft is controlled to descend vertically until the tail boom 13 touches the ground. Specifically, after the horizontal cruise flight ends, the aircraft arrives above the landing destination. The lift of the propeller 21 is reduced and the nose of the aircraft is raised, causing the aircraft to decelerate vertically upwards. When the aircraft decelerates vertically upwards to zero, the lift is increased to allow the aircraft to enter a hovering state. In the hovering state, the lift is slowly reduced, causing the aircraft to descend vertically until the contact point of the tail boom 13 touches the ground. Then, the lift generated by the propeller power system 2 is adjusted, and the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 is changed through the tilting mechanism 22 so that the thrust line of the propeller 21 remains perpendicular to the ground, thereby driving the aircraft body 1 to rotate from a vertical take-off and landing attitude to a horizontal parking attitude around the contact point of the tail boom 13. Specifically, after receiving the tail boom 13 touch-the-ground signal, the aircraft is controlled to hover briefly on the ground with the support of the tail boom 13. Then, the ailerons 121 on both sides are controlled to generate a nose-down moment, while the thrust of the propeller 21 is gradually reduced. The nose of the aircraft begins to tilt downwards, and the aircraft flips from a vertical to a horizontal attitude around the contact point of the tail boom 13. Throughout the tilting process, the tilting mechanism 22 continuously and dynamically adjusts the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 to ensure that the thrust line of the propeller 21 remains perpendicular to the ground, avoiding the generation of horizontal components that could cause the aircraft to slide. As the aircraft continues to tilt downwards, the support rod 24 gradually approaches the ground and eventually touches it, supporting the aircraft body 1 together with the tail boom 13. After the aircraft returns to a horizontal parking attitude, the propeller power system 2 is shut down, and the vertical landing is completed. During the ground tilting phase of the landing, the relationship between the thrust F of the propeller 21 and the support force D3 of the ground on the tail boom 13 gradually changes. As the aircraft tilts from a vertical to a horizontal position, the angle between the fuselage 11 and the ground gradually decreases. The tilting mechanism 22 drives the propeller 21 to tilt synchronously to maintain the verticality of the thrust line. Finally, when the aircraft fully returns to a horizontal parking position, the angle between the thrust line of the propeller 21 and the axis of the fuselage 11 returns to approximately 90°. Using this landing method, the aircraft descends vertically in a tail-sitting manner until the tail boom touches the ground, then tilts and returns to a horizontal parking position on the ground. The landing process is smooth, controllable, and highly safe. Furthermore, because the aircraft maintains contact or near-contact with the ground throughout the landing process, the impact and loss of control risks associated with hovering landings are avoided.

[0044] In summary, the vertical takeoff and landing aircraft and its takeoff and landing method provided in this application, by setting the tilt mechanism 22 on the aircraft body 1 to change the angle between the thrust line of the propeller 21 and the axis of the fuselage 11, and setting the point of application of the lift force of the propeller 21 in front of the center of gravity of the aircraft, enables the lift force of the propeller 21 to drive the aircraft body 1 to rotate around the contact point of the tail boom 13, thereby realizing the switching between the horizontal parking attitude and the vertical takeoff and landing attitude of the aircraft. Compared with the in-flight tilt rotor scheme, the tilting process of this application is completed on the ground. The tilt mechanism 22 does not need to participate in the flight attitude control of the aircraft after it leaves the ground. Therefore, the structural complexity, weight and manufacturing cost of the tilt mechanism 22 are significantly reduced, while avoiding the aerodynamic interference problem and center of gravity sensitivity problem during the in-flight tilting process. Since the tilt mechanism 22 only needs to complete the tilting of the propeller 21 on the ground and does not need to bear complex aerodynamic loads and perform high-frequency response in the air, the tilt mechanism 22 can adopt a simpler structure and lower strength requirements, further reducing costs. Compared to tail-sitting vertical takeoff and landing (VTOL) systems, the aircraft body 1 of this application maintains a horizontal attitude when parked, resulting in a low center of gravity, small frontal area, and reduced risk of tipping over in crosswinds, significantly improving its adaptability to takeoff and landing environments. The aircraft's parking position is similar to that of a conventional fixed-wing aircraft, exhibiting good ground stability. Furthermore, the aircraft body 1 can employ a conventional low-drag aerodynamic layout, unrestricted by the short, stubby fuselage of a tail-sitting system, which is beneficial for increasing flight speed and maneuverability. In addition, the tail boom 13 remains in contact with the ground throughout the tilting process, providing physical support and further enhancing the aircraft's stability and controllability during tilting. The support rod 24 is linked to the propeller 21, automatically retracting to a position parallel to the fuselage 11 axis during cruise flight, eliminating the need for an additional retraction mechanism, simplifying the structure and reducing weight. The counter-rotating configuration of the propeller 21 eliminates counter-torque, and differential thrust and slipstream control provide multiple means for attitude control of the aircraft in hovering conditions. This aircraft is suitable for both manned and unmanned flight, and has broad application prospects in fields such as combat in complex terrain, urban air traffic, and emergency rescue.

[0045] This application is illustrated through several specific embodiments. Those skilled in the art will understand that various modifications and equivalent substitutions can be made to this application without departing from its scope. Furthermore, various modifications can be made to this application for specific situations or circumstances without departing from its scope. Therefore, this application is not limited to the specific embodiments disclosed, but should include all embodiments falling within the scope of the claims of this application.

Claims

1. A vertical takeoff and landing aircraft, characterized in that, include: The aircraft body (1) includes a fuselage (11), wings (12) and tail boom (13). The tail boom (13) is located near the tail of the fuselage (11) and is used to support the aircraft body (1) when the aircraft is parked on the ground or when it is flipped on the ground. The propeller power system (2) includes a propeller (21) and a tilting mechanism (22). The propeller (21) is connected to the aircraft body (1) through the tilting mechanism (22) so as to change the angle between the thrust line of the propeller (21) and the axis of the fuselage (11). The propeller (21) exerts its lift force on the aircraft body (1) at a point closer to the head of the fuselage (11) than the center of gravity of the aircraft. The lift force exerted by the propeller (21) on the aircraft body (1) causes the aircraft body (1) to rotate around the contact point of the tail boom (13) to switch between a horizontal parking posture and a vertical take-off and landing posture.

2. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The tilting mechanism (22) is configured such that the angle between the thrust line of the propeller (21) and the axis of the fuselage (11) is adjustable in the range of -10° to 100°.

3. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The tilting mechanism (22) includes a fixed part (221) and a rotating part (222) pivotally connected to the fixed part (221). The fixed part (221) is mounted on the aircraft body (1), and the rotating part (222) is connected to the propeller (21). The propeller (21) adjusts the angle between itself and the axis of the fuselage (11) through the pivoting motion of the rotating part (222) relative to the fixed part (221).

4. The vertical takeoff and landing aircraft according to claim 1, characterized in that, During the process of the aircraft body (1) rotating around the contact point of the tail boom (13) to switch between a horizontal parking attitude and a vertical take-off and landing attitude, the propeller (21) is controlled so that its thrust line remains perpendicular to the ground to avoid horizontal drag of the tail boom (13) on the ground.

5. The vertical takeoff and landing aircraft according to claim 1, characterized in that, The tilting mechanism (22) is configured to maintain the angle between the propeller (21) and the fuselage (11) axis during the flight of the aircraft after it leaves the ground, so as not to participate in the flight attitude control of the aircraft.

6. The vertical takeoff and landing aircraft according to any one of claims 1 to 5, characterized in that, The aircraft also includes a support rod (24), which, when the aircraft is parked on the ground, serves as a front support member and together with the tail support (13) supports the aircraft body (1).

7. The vertical takeoff and landing aircraft according to claim 6, characterized in that, The support rod (24) is linked to the propeller (21), and when the angle between the tension line of the propeller (21) and the axis of the fuselage (11) approaches zero, the support rod (24) is in a retracted state that is close to parallel to the axis of the fuselage (11).

8. The vertical takeoff and landing aircraft according to any one of claims 1 to 5, characterized in that, The propeller power system (2) includes a left propeller (21) power unit and a right propeller (21) power unit disposed on the left and right wings (12). The left propeller (21) power unit and the right propeller (21) power unit are configured such that their propellers (21) can rotate in opposite directions to counteract the counter torque.

9. A takeoff method for a vertical takeoff and landing aircraft, characterized in that, For a vertical takeoff and landing aircraft as described in any one of claims 1 to 8, the takeoff method comprises: The aircraft is placed on the ground in a horizontal parking position; The propeller power system (2) is activated to generate lift force to lift the nose of the aircraft, and the angle between the thrust line of the propeller (21) and the axis of the fuselage (11) is changed by the tilting mechanism (22) so that the thrust line of the propeller (21) remains perpendicular to the ground, thereby driving the aircraft body (1) to flip from a horizontal parking posture to a vertical take-off and landing posture around the contact point of the tail boom (13); Apply a lift force sufficient to lift the aircraft off the ground to drive it to lift off the ground and ascend vertically.

10. A landing method for a vertical takeoff and landing aircraft, characterized in that, For a vertical takeoff and landing aircraft as described in any one of claims 1 to 8, the landing method comprises: In mid-air, the aircraft is converted to a vertical flight attitude and controlled to descend vertically until the tail boom (13) touches the ground; Adjust the lift generated by the propeller power system (2), and change the angle between the thrust line of the propeller (21) and the axis of the fuselage (11) through the tilting mechanism (22) so that the thrust line of the propeller (21) remains perpendicular to the ground, so as to drive the aircraft body (1) to flip from the vertical take-off and landing attitude to the horizontal parking attitude around the contact point of the tail boom (13).

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