Opening and closing paddle mechanism for vertical take-off and landing aircraft

Abstract

The invention relates to the field of aircrafts, in particular to an opening and closing propeller mechanism for a vertical take-off and landing aircraft, which comprises a base, an upper propeller hub and a lower propeller hub are arranged at the upper end of the base, both ends of the upper propeller hub and the lower propeller hub are fixedly connected with blades, the bottom end of the lower propeller hub is fixedly connected with a turntable, and the turntable is in running fit with the base. A driving motor is fixedly arranged at the bottom of the base, a switching assembly is arranged in the upper propeller hub and the lower propeller hub and comprises a rotating sleeve, the top end of the rotating sleeve is fixedly connected with the inner wall of the upper propeller hub, the bottom end of the rotating sleeve is rotationally matched with the inner wall of the lower propeller hub, a cylindrical cam is coaxially arranged in the rotating sleeve, and the top end of the cylindrical cam is fixedly connected with the rotating sleeve through a fixing gasket. The blades can be switched between an overlapped parallel state and a crossed vertical state, so that the air resistance of the aircraft during flat flight on a runway can be greatly reduced, and meanwhile, the lift force effect and the balance stability of the aircraft during vertical take-off are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft, and particularly to an opening and closing paddle mechanism for a vertical take-off and landing aircraft. Background Art

[0002] A vertical take-off and landing aircraft refers to an aircraft that can both vertically take off and land and hover in the air like a helicopter, and can also fly horizontally like a fixed-wing aircraft. This kind of aircraft combines the advantages of a helicopter and a fixed-wing aircraft, has the capabilities of vertical take-off and landing, hovering in the air, and horizontal flight. Its technical principles are diverse and it has a very broad application prospect.

[0003] Chinese Patent No. CN221294109U discloses a vertical take-off and landing aircraft, including: a fuselage, 2N tilting rotors. Wings are arranged on both sides of the fuselage, and a tail wing is arranged at the tail of the fuselage; 2N tilting rotors are symmetrically installed on both sides of the fuselage, and a part of the 2N tilting rotors are located on the tail wing; where N is a natural number greater than or equal to 2, and at least the tilting rotors located on the tail wing are fully tilting rotors. This vertical take-off and landing aircraft can improve the problem that the airflow interference between the tilting rotors on the tail wing and the tail wing in the existing vertical take-off and landing aircraft is relatively large and it is not easy to perform pitch control. However, this aircraft uses rotors, and multiple blades are fixedly arranged at equal intervals on the hub. When the aircraft flies horizontally on the runway, the airflow acting on the blades will greatly increase the air resistance, and at the same time, the torque acting on the blades is also not conducive to the service life of the blades. Summary of the Invention

[0004] The purpose of the present invention is to provide an opening and closing paddle mechanism for a vertical take-off and landing aircraft, aiming to solve the above technical problems.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] An opening and closing paddle mechanism for a vertical take-off and landing aircraft includes a base. An upper hub and a lower hub are arranged at the upper end of the base. Blades are fixedly connected to both ends of the upper hub and the lower hub. A turntable is fixedly connected to the bottom end of the lower hub, and the turntable is rotationally matched with the base. A driving motor is fixedly arranged at the bottom of the base. A switching component is arranged inside the upper hub and the lower hub. The switching component includes a rotating sleeve. The top end of the rotating sleeve is fixedly connected to the inner wall of the upper hub, and the bottom end of the rotating sleeve is rotationally matched with the inner wall of the lower hub. A cylindrical cam is coaxially arranged inside the rotating sleeve, and the top end of the cylindrical cam is fixedly connected to the rotating sleeve through a fixing gasket.

[0007] A lifting component is arranged inside the cylindrical cam. The lifting component includes a lower limit plate, a push rod, and an upper limit plate. The push rod coaxially and slidably penetrates through the top end of the cylindrical cam. The upper and lower ends of the push rod are respectively fixedly connected to the lower limit plate and the upper limit plate. Lower limit columns are fixedly arranged at the top of both ends of the lower limit plate, and upper limit columns are fixedly arranged at the bottom of both ends of the upper limit plate. Upper limit holes corresponding to the upper limit columns are penetrated and arranged at the bottom inside the upper paddle hub, and lower limit holes corresponding to the lower limit columns are penetrated and arranged at the bottom inside the lower paddle hub.

[0008] A cam groove is penetrated and arranged on the outer wall of the cylindrical cam. The cam groove includes a lower limit straight groove, an inclined sliding groove, and an upper limit straight groove. The two ends of the inclined sliding groove are smoothly and transitionally communicated with the lower limit straight groove and the upper limit straight groove respectively. A cam pin shaft is fixedly connected to the outer wall of the push rod, and the cam pin shaft is adaptively and slidably installed in the cam groove.

[0009] A linear servo is arranged below the lower limit plate. The linear servo is fixedly installed on a servo base. The output end of the linear servo is fixedly connected to the lower limit plate, and the output end of the driving motor is fixedly connected to the servo base.

[0010] As a further scheme of the present invention: The upper limit plate is arranged inside the upper paddle hub. A locking bolt is fixedly arranged at the center of the upper end of the upper limit plate. The locking bolt is connected to the top end of the push rod. A stop hole facing the locking bolt is arranged at the top inside the upper paddle hub.

[0011] As a further scheme of the present invention: The edge of the upper end of the upper limit hole extends upward to form a hole edge.

[0012] As a further scheme of the present invention: Positioning holes are penetrated and arranged at the top of the lower paddle hub. The positioning holes are arranged in one-to-one correspondence with the upper limit holes.

[0013] As a further scheme of the present invention: When the cam pin shaft slides out of the lower limit straight groove and slides into the upper limit straight groove through the inclined sliding groove, it will drive the cylindrical cam to rotate synchronously by 90°.

[0014] As a further scheme of the present invention: The vertical displacement distance of the cam pin shaft from the lower limit straight groove to the upper limit straight groove is less than the sum of the depths of the upper limit hole and the positioning hole.

[0015] As a further scheme of the present invention: The vertical displacement distance of the cam pin shaft from the lower limit straight groove to the upper limit straight groove is greater than the interval distance between the top end of the lower limit column and the lower limit hole.

[0016] As a further scheme of the present invention: The bottom of the upper paddle hub and the top of the lower paddle hub are rotationally matched through a thrust bearing.

[0017] As a further solution of the present invention: The outer wall of the rotating sleeve is rotatably installed in the lower hub through a deep groove ball bearing, and a round nut is provided at the bottom of the outer side of the rotating sleeve.

[0018] The beneficial effects of the present invention: By setting the cylindrical cam and the lifting component, in the initial state, the two groups of blades of the upper hub and the lower hub are parallel and overlapped with each other. At this time, the upper limit post passes through the upper limit hole of the upper hub and the positioning hole of the lower hub, and the upper hub and the lower hub are relatively constrained and fixed, so that the two groups of blades can always maintain a parallel and overlapping state without circumferential rotational displacement. When the aircraft is flying horizontally, the blades are along the horizontal flight direction, which can greatly reduce the air resistance of the aircraft during horizontal flight on the runway. When the linear servo pushes the lower limit plate upward, at this time, the ejector rod will drive the cam pin to move linearly. Using the sliding fit between the cam pin and the cam groove, when the cam pin moves, it will drive the cylindrical cam and the upper hub to rotate until it rotates 90° so that the two groups of blades are cross-perpendicular. At this time, the upper limit post disengages from the positioning hole but still passes through the upper limit hole, and at the same time, the lower limit post passes through the lower limit hole, and the upper hub and the lower hub remain relatively stable, so that the two groups of blades can always maintain a cross-perpendicular state, improving the lift effect and balance stability of the aircraft during vertical takeoff. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 is the overall structural schematic diagram of the present invention.

[0021] Figure 2 is the internal structural schematic diagram of the present invention.

[0022] Figure 3 is the cross-sectional schematic diagram of the upper hub and the lower hub of the present invention.

[0023] Figure 4 is the internal structural schematic diagram of the upper hub and the lower hub of the present invention.

[0024] Figure 5 is the structural schematic diagram of the switching component of the present invention.

[0025] Figure 6 is the structural schematic diagram of the lifting component of the present invention.

[0026] Figure 7 is the structural schematic diagram of the cylindrical cam in the overlapping state of the present invention.

[0027] Figure 8 is the structural schematic diagram of the cylindrical cam in the open and closed state of the present invention.

[0028] Figure 9 is the structural schematic diagram of the present invention when the blades are in the open and closed state.

[0029] In the figure: 1, base; 2, drive motor; 3, upper hub; 301, upper limit hole; 302, stop hole; 303, thrust bearing; 4, lower hub; 401, positioning hole; 402, lower limit hole; 403, deep groove ball bearing; 404, round nut; 5, blade; 6, turntable; 7, switching component; 710, rotating sleeve; 720, cylindrical cam; 721, lower limit straight groove; 722, inclined chute; 723, upper limit straight groove; 730, fixing gasket; 8, lifting component; 810, lower limit plate; 811, lower limit post; 812, mounting socket; 820, ejector rod; 821, cam pin shaft; 830, upper limit plate; 831, upper limit post; 832, locking bolt; 9, linear servo; 901, servo base. Specific embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0031] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown in, the present invention is an opening and closing paddle mechanism for a vertical take-off and landing aircraft, including a base 1. An upper hub 3 and a lower hub 4 are provided at the upper end of the base 1. Blades 5 are fixedly connected to both ends of the upper hub 3 and the lower hub 4. A turntable 6 is fixedly connected to the bottom end of the lower hub 4. The turntable 6 is rotationally matched with the base 1. A drive motor 2 is fixedly provided at the bottom of the base 1. A switching component 7 is arranged inside the upper hub 3 and the lower hub 4. The switching component 7 includes a rotating sleeve 710. The top end of the rotating sleeve 710 is fixedly connected to the inner wall of the upper hub 3. The bottom end of the rotating sleeve 710 is rotationally matched with the inner wall of the lower hub 4. A cylindrical cam 720 is coaxially arranged inside the rotating sleeve 710. The top end of the cylindrical cam 720 is fixedly connected to the rotating sleeve 710 through a fixing gasket 730.

[0032] Specifically, since the rotating sleeve 710 is fixedly connected to the upper hub 3 and rotationally matched with the lower hub 4, when the cylindrical cam 720 rotates, it will drive the rotating sleeve 710 to rotate synchronously, so that the upper hub 3 rotates relative to the lower hub 4, and thus the included angle between the two groups of blades 5 can be adjusted.

[0033] As Figures 3 - 6As shown in the figure, a lifting assembly 8 is provided inside the cylindrical cam 720. The lifting assembly 8 includes a lower limit plate 810, a push rod 820, and an upper limit plate 830. The push rod 820 coaxially and slidably penetrates through the top end of the cylindrical cam 720. The upper and lower ends of the push rod 820 are respectively fixedly connected to the lower limit plate 810 and the upper limit plate 830. At the top of both ends of the lower limit plate 810, lower limit posts 811 are fixedly provided. At the bottom of both ends of the upper limit plate 830, upper limit posts 831 are fixedly provided. At the bottom inside the upper paddle hub 3, upper limit holes 301 corresponding to the upper limit posts 831 are penetrated and provided. At the bottom inside the lower paddle hub 4, lower limit holes 402 corresponding to the lower limit posts 811 are penetrated and provided.

[0034] As Figures 2 - 7 shown in the figure, a cam groove is penetrated and provided on the outer wall of the cylindrical cam 720. The cam groove includes a lower limit straight groove 721, an inclined sliding groove 722, and an upper limit straight groove 723. The two ends of the inclined sliding groove 722 are respectively in smooth transition connection with the lower limit straight groove 721 and the upper limit straight groove 723. A cam pin shaft 821 is fixedly connected to the outer wall of the push rod 820. The cam pin shaft 821 is adaptively and slidably installed in the cam groove.

[0035] Among them, a linear servo 9 is provided below the lower limit plate 810. The linear servo 9 is fixedly installed on the servo base 901. The output end of the linear servo 9 is fixedly connected to the lower limit plate 810. The output end of the drive motor 2 is fixedly connected to the servo base 901.

[0036] Specifically, by setting the cylindrical cam 720 and the lifting assembly 8, in the initial state, the two groups of blades 5 of the upper paddle hub 3 and the lower paddle hub 4 overlap parallel to each other. At this time, the upper limit posts 831 penetrate through the upper limit holes 301 of the upper paddle hub 3 and the positioning holes 401 of the lower paddle hub 4. The upper paddle hub 3 and the lower paddle hub 4 are relatively constrained and fixed, so that the two groups of blades 5 can always maintain a parallel overlapping state without circumferential rotational displacement. When the aircraft flies horizontally, the blades 5 are along the horizontal flight direction, which can greatly reduce the air resistance of the aircraft during horizontal flight on the runway. When the linear servo 9 pushes the lower limit plate 810 upward, at this time, the push rod 820 will drive the cam pin shaft 821 to move linearly. By using the sliding cooperation between the cam pin shaft 821 and the cam groove, when the cam pin shaft 821 moves, it will drive the cylindrical cam 720 and the upper paddle hub 3 to rotate until it rotates 90° so that the two groups of blades 5 cross vertically. At this time, the upper limit posts 831 are disengaged from the positioning holes 401 but still penetrate through the upper limit holes 301. At the same time, the lower limit posts 811 penetrate through the lower limit holes 402. The upper paddle hub 3 and the lower paddle hub 4 remain relatively stable, so that the two groups of blades 5 can always maintain a cross-vertical state, improving the lift effect and balance stability of the aircraft during vertical takeoff.

[0037] It should be noted that the opening and closing blade structure in the present invention can be applied to aircraft in other fields, not limited to vertical takeoff and landing aircraft only.

[0038] As Figures 4 - 6 shown, the upper limit plate 830 is arranged in the upper hub 3. A locking bolt 832 is fixedly arranged at the center of the upper end of the upper limit plate 830. The locking bolt 832 is connected to the top end of the ejector rod 820. A stop hole 302 facing the locking bolt 832 is arranged at the top inside the upper hub 3.

[0039] Specifically, when the linear servo 9 pushes the lower limit plate 810 to lift upward, the upper limit plate 830 will also move synchronously until the locking bolt 832 abuts and enters the stop hole 302. At this time, the cam pin 821 will also move into the upper limit straight groove 723 at the top end, so as to be able to stop and limit the lifting process of the upper limit plate 830 and the lower limit plate 810, and avoid excessive lifting.

[0040] As Figure 4 and Figure 6 shown, a hole edge extends upward from the edge of the upper end of the upper limit hole 301.

[0041] Specifically, the hole edge can effectively increase the depth of the upper limit hole 301 and prevent the upper limit post 831 from disengaging from the upper limit hole 301.

[0042] As Figure 4 and Figure 6 shown, a positioning hole 401 is arranged through the top of the lower hub 4, and the positioning hole 401 is arranged in one-to-one correspondence with the upper limit hole 301.

[0043] Specifically, the positioning hole 401 not only corresponds to the position of the upper limit hole 301, but also has the same aperture as the upper limit hole 301, so that the upper limit post 831 can penetrate the upper limit hole 301 and extend downward into the positioning hole 401 in the initial state.

[0044] As Figures 2 - 9 shown, when the cam pin 821 slides out of the lower limit straight groove 721 and slides to the upper limit straight groove 723 through the inclined chute 722, it will drive the cylindrical cam 720 to rotate synchronously by 90°.

[0045] Furthermore, the vertical displacement distance of the cam pin 821 from the lower limit straight groove 721 to the upper limit straight groove 723 is less than the sum of the depths of the upper limit hole 301 and the positioning hole 401.

[0046] Even further, the vertical displacement distance of the cam pin 821 from the lower limit straight groove 721 to the upper limit straight groove 723 is greater than the interval distance between the top end of the lower limit post 811 and the lower limit hole 402.

[0047] Specifically, in the initial state, the two sets of blades 5 are kept parallel and overlapping. At this time, the upper limit post 831 passes through the upper limit hole 301 and the positioning hole 401 at the same time, so that the upper hub 3 and the lower hub 4 are kept relatively fixed. At the same time, the cam pin shaft 821 is located in the lower limit straight groove 721. When the cam pin shaft 821 slides upward out of the lower limit straight groove 721, the upper limit post 831 will be disengaged upward from the positioning hole 401. When the cam pin shaft 821 continues to move upward and slides along the inclined chute 722, it will drive the cylindrical cam 720 to start rotating until the cam pin shaft 821 is lifted into the upper limit straight groove 723. At this time, the cylindrical cam 720 rotates 90°. At the same time, the upper limit post 831 still passes through the upper limit hole 301, and the lower limit post 811 will pass through the lower limit hole 402 during the lifting process. By using the constraint and limiting effects of the upper limit post 831 and the lower limit post 811, the upper hub 3 and the lower hub 4 are kept relatively fixed and will not rotate and shift, so that the two sets of blades 5 can be kept in a cross-perpendicular state.

[0048] As Figure 2 and Figure 4 shown, the bottom of the upper hub 3 and the top of the lower hub 4 are rotationally matched through a thrust bearing 303.

[0049] Specifically, the upper hub 3 and the lower hub 4 can rotate relative to each other through the thrust bearing 303, which is beneficial to the smooth progress of the process of adjusting the angle of the blade 5.

[0050] As Figure 4 shown, the outer wall of the rotating sleeve 710 is rotationally installed in the lower hub 4 through a deep groove ball bearing 403, and a round nut 404 is arranged at the bottom outside the rotating sleeve 710.

[0051] Specifically, the deep groove ball bearing 403 effectively ensures the stability of the rotating sleeve 710 when rotating relative to the lower hub 4, and at the same time, the round nut 404 is used for axially fixing the deep groove ball bearing 403.

[0052] The working principle of the present invention: As Figures 1 - 9As shown, in the initial state, the two sets of blades 5 of the upper hub 3 and the lower hub 4 overlap parallel to each other. At this time, the upper limit post 831 passes through the upper limit hole 301 of the upper hub 3 and the positioning hole 401 of the lower hub 4. At the same time, the cam pin shaft 821 is located in the lower limit straight groove 721. The upper hub 3 and the lower hub 4 are relatively constrained and fixed, so that the two sets of blades 5 can always maintain a parallel overlapping state. When the blades 5 bear the airflow, they generate a moment and will not undergo circumferential rotational displacement, thereby reducing the air resistance of the aircraft during level flight. When the linear servo 9 pushes the lower limit plate 810 upward, at this time, the push rod 820 will drive the cam pin shaft 821 to move linearly. When the cam pin shaft 821 slides upward out of the lower limit straight groove 721, at this time, the upper limit post 831 will be disengaged upward from the positioning hole 401. When the cam pin shaft 821 continues to move upward and slides along the inclined chute 722, it will drive the cylindrical cam 720 to start rotating until the cam pin shaft 821 is lifted into the upper limit straight groove 723. At this time, the cylindrical cam 720 rotates 90°. At the same time, the upper limit post 831 still passes through the upper limit hole 301, and the lower limit post 811 will be inserted into the lower limit hole 402 during the lifting process. By using the constraint and limiting effects of the upper limit post 831 and the lower limit post 811, the upper hub 3 and the lower hub 4 are kept relatively fixed and will not undergo rotational displacement, and the two sets of blades 5 can always maintain a cross-perpendicular state, improving the lift effect and balance stability of the aircraft during vertical takeoff.

[0053] The above has described an embodiment of the present invention in detail, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. An opening and closing paddle mechanism for a vertical takeoff and landing aircraft, comprising a base (1), an upper paddle hub (3) and a lower paddle hub (4) are arranged at the upper end of the base (1), and paddle blades (5) are fixedly connected to both ends of the upper paddle hub (3) and the lower paddle hub (4), characterized in that, A switching component (7) is arranged inside the upper hub (3) and the lower hub (4). The switching component (7) includes a rotating sleeve (710). The top end of the rotating sleeve (710) is fixedly connected to the inner wall of the upper hub (3), and the bottom end of the rotating sleeve (710) is rotatably matched with the inner wall of the lower hub (4). A cylindrical cam (720) is coaxially arranged inside the rotating sleeve (710), and the top end of the cylindrical cam (720) is fixedly connected to the rotating sleeve (710) through a fixing gasket (730). A lifting component (8) is arranged inside the cylindrical cam (720). The lifting component (8) includes a lower limiting plate (810), a top rod (820) and an upper limiting plate (830). The top rod (820) coaxially slides through the top end of the cylindrical cam (720), and the upper and lower ends of the top rod (820) are respectively fixedly connected to the lower limiting plate (810) and the upper limiting plate (830). Lower limiting columns (811) are fixedly arranged at the top of both ends of the lower limiting plate (810), and upper limiting columns (831) are fixedly arranged at the bottom of both ends of the upper limiting plate (830). Upper limiting holes (301) corresponding to the upper limiting columns (831) are arranged through the bottom inside the upper hub (3), and lower limiting holes (402) corresponding to the lower limiting columns (811) are arranged through the bottom inside the lower hub (4).

2. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 1, characterized in that, A turntable (6) is fixedly connected to the bottom end of the lower hub (4). The turntable (6) is rotatably matched with the base (1). A driving motor (2) is fixedly arranged at the bottom of the base (1). A linear servo (9) is arranged below the lower limiting plate (810). The linear servo (9) is fixedly installed on a servo base (901). The output end of the linear servo (9) is fixedly connected to the lower limiting plate (810), and the output end of the driving motor (2) is fixedly connected to the servo base (901).

3. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 1, wherein A cam groove is arranged through the outer wall of the cylindrical cam (720). The cam groove includes a lower limiting straight groove (721), an inclined sliding groove (722) and an upper limiting straight groove (723). The two ends of the inclined sliding groove (722) are smoothly and transitionally connected to the lower limiting straight groove (721) and the upper limiting straight groove (723) respectively. A cam pin shaft (821) is fixedly connected to the outer wall of the top rod (820), and the cam pin shaft (821) is slidably installed in the cam groove in a matching manner.

4. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 1, characterized in that, The upper limiting plate (830) is arranged inside the upper hub (3). A locking bolt (832) is fixedly arranged at the center of the upper end of the upper limiting plate (830). The locking bolt (832) is connected to the top end of the top rod (820). A stop hole (302) facing the locking bolt (832) is arranged at the top inside the upper hub (3).

5. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 3, characterized in that, A hole edge extends upward from the edge of the upper end of the upper limiting hole (301). A positioning hole (401) is arranged through the top of the lower hub (4). The positioning hole (401) is arranged corresponding to the upper limiting hole (301).

6. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 5, characterized in that The cam pin shaft (821) slides out of the lower limit straight groove (721), slides through the inclined chute (722) and into the upper limit straight groove (723), which will drive the cylindrical cam (720) to rotate synchronously by 90°.

7. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 6, characterized in that, The vertical displacement distance of the cam pin shaft (821) from the lower limit straight groove (721) to the upper limit straight groove (723) is less than the sum of the hole depths of the upper limit hole (301) and the positioning hole (401).

8. The opening and closing paddle mechanism for a vertical take-off and landing aircraft according to claim 7, characterized in that The vertical displacement distance of the cam pin shaft (821) from the lower limit straight groove (721) to the upper limit straight groove (723) is greater than the interval distance between the top of the lower limit column (811) and the lower limit hole (402).

9. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 1, characterized in that The bottom of the upper hub (3) and the top of the lower hub (4) are rotationally matched through a thrust bearing (303).

10. The opening and closing paddle mechanism for a vertical takeoff and landing aircraft according to claim 1, characterized in that, The outer wall of the rotating sleeve (710) is rotationally installed in the lower hub (4) through a deep groove ball bearing (403), and a round nut (404) is arranged at the outer bottom of the rotating sleeve (710).

Images