Bionic wing surface and folding flapping structure of a flapping-wing aircraft

Abstract

The present invention discloses a bionic wing surface and its folding and flapping structure of a flapping-wing aircraft, which relates to the field of wings and drive structures of flapping-wing aircrafts. A driving element is used to achieve the flapping and wing unfolding of the flapping-wing aircraft. The bionic flapping-wing aircraft includes a fuselage, a pair of folding wings, and a V-shaped tail. The pair of folding wings and the V-shaped tail are symmetrically distributed on both sides of the fuselage of the flapping-wing aircraft respectively; the folding wings include a wing rod connected to the fuselage and a wing membrane connected to the wing rod; the wing rod includes a first wing rod, a second wing rod, a first outer wing rod, and a second outer wing rod, which realizes folding with a simple and lightweight structure, has a small increased mass, and generates a small inertial force; the bionic flapping-wing aircraft further includes a motor fixedly installed on the fuselage, a sixth gear in linkage with the motor, a second connecting rod connected between the sixth gear and the first wing rod, and a first connecting rod connected between the sixth gear and a connecting member. The three-segment wing designed by this structure is extremely similar to the folding of the wings of a pigeon during flight, and has strong bionics.

Description

Technical Field

[0001] The present invention relates to the field of wings and drive structures of flapping-wing aircraft, and specifically to a bionic wing surface and its folding and flapping structure of a flapping-wing aircraft. Background Art

[0002] A flapping-wing aircraft is a bionic aircraft whose design inspiration comes from the flight mode of birds. Different from traditional fixed-wing flapping-wing aircraft, a bionic folding-wing flapping-wing aircraft generates lift and thrust by folding its wing shape during flight, thus achieving flight. When a bird is flying, its wings will fold, enabling it to obtain better aerodynamic effects. A bionic flapping-wing aircraft also needs to improve its aerodynamic characteristics through some structural changes during flight. Currently, certain research has been conducted on the wing structures of flapping-wing aircraft at home and abroad. For example, in 2022, Cai Yu from Guangxi University introduced a "flapping - folding" flapping-wing mechanism in the paper "Design and Aerodynamic Simulation Analysis of a Folding-Wing Aircraft", which enables the wing to perform a folding movement perpendicular to the body axis while flapping, and conducted aerodynamic analysis. In 2022, Cristina Ruiz et al. from the University of Seville in Spain introduced a flapping-wing aircraft with a deformable wing in the paper "Optimal elastic wing for flapping-wing robots through passive morphing", and found through experiments that its lift increased by 16%.

[0003] However, most of the current research on deformable-wing flapping-wing aircraft is about deformation in the plane perpendicular to the body axis. There is very little deformation in the plane parallel to the body axis, and the folding movement of the wings in the plane parallel to the body axis truly exists during animal flight. Most of the existing wing folding mechanisms of flapping-wing aircraft in the body axis plane are complex, heavy, and require additional drive components other than the drive flapping mechanism. Compared with flapping-wing aircraft without folding function, a lot of additional mass is required to achieve the folding movement and control of the wings, resulting in a relatively large inertial force generated by the wings during the flight of the aircraft, which is not conducive to flight stability, coordinated control of folding and flapping, and reduction of the energy consumption of the flapping-wing aircraft. Summary of the Invention

[0004] In view of the above problems, the present invention proposes a bionic wing surface and its folding and flapping structure of a flapping-wing aircraft, which uses one drive component to achieve the flapping of the flapping-wing aircraft and the unfolding of the wings.

[0005] The technical solution of the present invention is as follows: The bionic flapping-wing aircraft includes a fuselage, a pair of folding wings, and a V-shaped tail. The pair of folding wings and the V-shaped tail are symmetrically distributed on both sides of the fuselage of the flapping-wing aircraft respectively;

[0006] The folding wing includes a wing rod (2) connected to the fuselage and a wing membrane (1) connected to the wing rod (2);

[0007] The wing rod (2) includes a first wing rod (3), a second wing rod (4), a first outer wing rod (5) and a second outer wing rod (6). The middle parts of the first wing rod (3) and the second wing rod (4) are hinged. The root of the second outer wing rod (6) is hinged to the first wing rod (3). The two ends of the first outer wing rod (5) are respectively hinged to the second wing rod (4) and the second outer wing rod (6), so that a rhombus is formed among the first wing rod (3), the second wing rod (4), the first outer wing rod (5) and the second outer wing rod (6). The folding of the wing is realized by using this rhombus mechanism, which has a simple structure and light weight. Compared with complex wing folding mechanisms, it is beneficial to reduce the inertial force generated during the flapping and folding of the wing, thus being beneficial to the flight stability of the aircraft.

[0008] A first connecting piece (8) that can be turned up and down is hinged on the fuselage. The root of the second wing rod (4) is hinged on the first connecting piece (8), and the second wing rod (4) can swing back and forth relative to the first connecting piece (8);

[0009] A rod (11) arranged along its length direction is fixedly connected to the fuselage. A third connecting piece (10) that is slidably connected to it is sleeved on the rod (11). A second connecting piece (9) that can be turned up and down is hinged on the third connecting piece (10). The root of the first wing rod (3) is hinged on the second connecting piece (9), and the first wing rod (3) can swing back and forth relative to the second connecting piece (9); In this way, when the second wing rod (4) swings up and down relative to the fuselage, since the root of the first wing rod (3) is in a freely turnable state with the fuselage, therefore, the first wing rod (3), the second wing rod (4), the first outer wing rod (5) and the second outer wing rod (6) will also make synchronous up and down turns; And when the distance between the roots of the first wing rod (3) and the second wing rod (4) changes, that is, when the third connecting piece (10) slides on the rod (11), affected by the rhombus structure, the first wing rod (3), the second wing rod (4), the first outer wing rod (5) and the second outer wing rod (6) can contract inwards synchronously or expand outwards synchronously;

[0010] The bionic flapping-wing aircraft further includes a motor (12) fixedly installed on the fuselage, a sixth gear (19) in linkage with the motor (12), a second connecting rod (21) connected between the sixth gear (19) and the first wing rod (3), and a first connecting rod (20) connected between the sixth gear (19) and the third connecting piece (10);

[0011] The sixth gear (19) is arranged perpendicular to the longitudinal direction of the fuselage, and its center is rotatably connected to the fuselage. One end of the second connecting rod (21) is movably connected to the surface of the sixth gear (19) through a spherical hinge, and the other end is movably connected to the first connecting member (8) through a ball pin hinge. Both ends of the first connecting rod (20) are directly hinged to the surface of the sixth gear (19) and the third connecting member (10). In this way, when the motor receives a signal and starts to rotate, it will drive the sixth gear (19) to rotate around its own axis. Thereafter, the flapping mechanism composed of the sixth gear 19, the second connecting rod 21, and the first connecting member 8 will cause the first connecting member 8 and the wing rod 2 as a whole to move up and down reciprocally under the influence of the ball hinge structure, while the folding mechanism composed of the sixth gear 19, the first connecting rod 20, and the third connecting member 10, which is also a crank-slider mechanism, will cause the third connecting member 10 to slide back and forth reciprocally, so as to fold or unfold the wing rod 2 as a whole.

[0012] Finally, folding and flapping are achieved through a single driving element. The folding and flapping driving structures are simple and lightweight. During flight, when the wings flap downwards, the wings on both sides of the fuselage gradually unfold, increasing the area of their wing surfaces, thereby enhancing the lift force; when the wings flap upwards, the wings on both sides of the fuselage gradually fold, reducing the area of their wing surfaces, thereby reducing the resistance generated during the upward flapping, improving the aerodynamic characteristics of the flapping-wing aircraft during flight, and reducing the flight energy consumption.

[0013] In addition, the wing folding mechanism of the present invention is relatively simple and lightweight. Applying it to a flapping-wing aircraft is beneficial for reducing the weight brought about by adding a folding mechanism. Reducing the weight increased by the folding wings is conducive to reducing the inertial force generated during the up-and-down flapping and folding movements of the wings of the flapping-wing aircraft during flight, and reducing the possibility of sudden changes in the flight action posture affected by the inertial force of the wings, thereby ensuring flight stability and reducing the energy consumed by the aircraft to overcome its own mass and movement inertial force. The folding mechanism of the present invention can be folded in a non-working state, facilitating the storage and transportation of the flapping-wing aircraft. The folding and flapping of the wings adopt the same driving element. Through a clever structural design, the folding and flapping of the aircraft wings are coordinated with each other, reducing the mass of the additional driving elements and their electronic devices that need to be added due to the addition of the folding mechanism, and avoiding the coordinated control design of the driving elements that separately drive the folding and flapping movements of the aircraft wings. The wing and its folding and flapping mechanism in the present invention have a simple structure, are easy to design and control, have a small mass, and play a significant role in reducing the inertial force during the flight of the aircraft, enhancing flight stability, and reducing flight energy consumption. The folding wing structure of the present invention is also applicable to flapping-wing aircraft with a small load capacity and a small size.

[0014] Further, the wing membrane (1) is an ultra-thin TPU soft film. The leading edge of the wing membrane (1) is pasted on the leading edge of the wing rod (2), and folds and unfolds as the structure of the wing rod changes. Taking the left wing as an example, the leading edge of the wing membrane (1) is pasted on the parts of the second wing rod (4), the first wing rod (3), and the second outer wing rod (6) that are located on the leading edge of the wing rod from inside to outside. Below the wing rod (2), there are also a wing surface support rod (49), a fourth connecting piece (50), and a fifth connecting piece (51) installed to fix the wing surface, so as to ensure the aerodynamic effect of the wing surface. One end of the wing surface support rod (49) is hinged to both the first wing rod (3) and the second outer wing rod (6), and the other end is fixedly connected to the wing membrane (1). The fourth connecting piece (50) is hinged to the second wing rod (4) and the first outer wing rod (5). The wing surface support rod (49) passes through the fourth connecting piece (50) and is slidably connected thereto. When the angle of the wing rod (2) changes, the wing surface support rod (49) and the fourth connecting piece (50) can slide relative to each other. The fifth connecting piece (51) is fixedly installed on the wing surface support rod (49), and is adhered to the wing membrane (1) above it to play a fixing role.

[0015] Further, the motor (12) and the sixth gear (19) are kept in linkage through a two-stage reduction transmission mechanism; the total reduction ratio of the two-stage reduction gears is 10;

[0016] The two-stage reduction transmission mechanism includes a first gear (13), a second gear (15), a third gear (16), a fourth gear (17), a fifth gear (18), and a sixth gear (19). The third gear (16) is fixedly connected to the output shaft of the motor (12) and meshes with the fifth gear (18) to achieve the first-stage reduction. The first gear (13), the fourth gear (17), and the fifth gear (18) that are rotatably connected to the fuselage are coaxial and fixedly connected to each other, with the same rotational speed, and can rotate around the same shaft two (27). The first gear (13) and the fourth gear (17) are symmetrically installed on the outside of the fuselage, and the fifth gear (18) is installed on the inside of the fuselage. The second gear (15) and the sixth gear (19) are fixedly installed on the same shaft one (25), and the two gears are symmetrically installed on the outside of the fuselage with the same rotational speed. The first gear (13) meshes with the second gear (15), and the fourth gear (17) meshes with the sixth gear (19) to achieve the second-stage reduction. The number of teeth of the first gear (13) is 10, the number of teeth of the second gear (15) is 40, the number of teeth of the third gear (16) is 20, the number of teeth of the fourth gear (17) is 10, the number of teeth of the fifth gear (18) is 50, and the number of teeth of the sixth gear (19) is 40, and the total reduction ratio is 10.

[0017] Further, the rotation speed of the motor (12) is controlled by an electronic speed controller (47), and the electronic speed controller (47) inputs the received control signal through a receiver (46). The motor (12), the electronic speed controller (47), and the receiver (46) are all powered by a battery (44). The motor (12), the electronic speed controller (47), and the receiver (46) are fixedly arranged on one side of the fuselage, while the battery (44) is arranged on the other side of the fuselage. This makes the mass distribution on both sides of the fuselage of the flapping-wing aircraft more balanced.

[0018] Further, the V-shaped tail is composed of a pair of tail wings. A tail wing rudder surface is hinged to the tail of the tail wing, and a servo motor for driving the tail wing rudder surface is provided on the tail wing. The servo motor is also connected to the receiver.

[0019] The control of the flight attitude of the flapping-wing aircraft is mainly controlled by the signal sent by the receiver (46). The on-board electronic devices of the entire flapping-wing aircraft include the receiver (46), the electronic speed controller (47), the motor (12), the battery (44), the servo motor one (33), and the servo motor two (37). The pilot sends a 2.4G signal through a flight remote control according to the flight mission and flight attitude of the flapping-wing aircraft. The signal is received by the receiver (46), and then the receiver (46) transmits it to other electronic devices. Through the transmission of the signal, the changes in the motor rotation speed and the servo motor angle can be realized, and finally the flight speed and flight attitude of the flapping-wing aircraft can be adjusted.

[0020] The present invention uses one drive to complete the flapping of the wings of the flapping-wing aircraft and the folding within the wing surface. At the same time, it cleverly realizes the coordinated cooperation between the wing folding and the flapping motion, so that the wing surface folds when the wing flaps upward and unfolds when the wing flaps downward; it avoids the complex control design required for the drive elements that separately drive the wing folding and the flapping in order to achieve the coordinated motion of the wing folding and the flapping. At the same time, it achieves the technical effects of increasing the limit angle of the upward flap of the wing, increasing the folding scale of the opening and closing within the wing surface, and reducing the wing surface size during the upward flap process, which is beneficial to reducing the flapping resistance of the wing. The three-section wing structure is more similar to the bird bone structure and has a stronger biomimetic property. The present invention mainly uses a motor to drive a gear, which drives the wing through a two-stage reduction via a spherical pair and a ball pin pair. The drive mechanism gear simultaneously drives a crank-slider mechanism to achieve linear movement, so as to complete the folding motion on the basis of the flapping of the wings of the flapping-wing aircraft. The wing folding uses a rhombus mechanism, which has a simple structure and a light weight. The V-shaped tail structure is adopted at the tail of the present invention, which is simple in structure and easy to control; the fuselage uses a carbon fiber board, which is light in weight. The entire drive and folding structure effectively solves the problem of large flapping resistance of the flapping-wing aircraft and overcomes the problem of limited load capacity of the flapping-wing aircraft.

[0021] The present invention adopts a driving element to simultaneously achieve the bionic drive of wing flapping and folding within the body axis plane, as well as a three-stage folding mechanism. By recording the posture of a pigeon during flight, the three-stage wings designed in this structure are extremely similar to the folding of a pigeon's wings during flight, with strong bionics. The wing structure of the present invention is simple. The carbon fiber rods used are low in price and light in weight, which can solve the problems of low load capacity during the flight of a flapping-wing aircraft and large inertial forces generated by the large mass of complex folding structures, affecting flight stability. In terms of the flight aerodynamics of a flapping-wing aircraft, the combined flapping and folding motion achieved by the present invention effectively solves the problem of large resistance and wasted energy when the wings of a flapping-wing aircraft flap upwards.

[0022] The present invention has the following beneficial effects:

[0023] First, a bionic wing surface and its folding and flapping structure are designed according to the changes of a bird's wings during flight, with good aerodynamic performance. On the basis of designing the folding structure, a driving structure and a control scheme are designed and used on a flapping-wing aircraft, providing a reliable solution for improving the flight performance of a flapping-wing aircraft.

[0024] Second, the wing folding structure of the present invention completely imitates the bones of a bird. The three-stage structure of the wing is similar to the three-stage bones of a bird. The wing membrane fits perfectly with the wing rod, and its changing posture is exactly the same as that of the wing rod.

[0025] Third, the present invention combines the folding and flapping of the wings on one driving element, and uses one driving mechanism to achieve the coordinated motion of the flapping and wing folding of a flapping-wing aircraft, reducing the number of prime movers that the flapping-wing aircraft needs to carry, reducing the weight of the additional airborne electronic equipment, avoiding complex control designs, and the driving structure can be applied to the design scheme of a flapping-wing aircraft.

[0026] Fourth, the folding amount and flapping amplitude of the wings of the flapping-wing aircraft of the present invention can be changed by changing the rod lengths of the wing rods in the structure and the connecting rods in the drive, and it can be applied to flapping-wing aircrafts with similar functions of different sizes, which is beneficial to improving certain flight aerodynamic performance.

[0027] Fifth, the bionic wing surface, its folding and flapping structure and control of the present invention are simple. To a certain extent, it enhances the downward flapping lift of the wings of a flapping-wing aircraft, realizes the folding within the wing surface of a flapping-wing aircraft, reduces the upward flapping resistance of the wings of a flapping-wing aircraft, and increases the upward flapping limit angle of the wings; the simple and lightweight wing folding structure is beneficial to reducing the wing mass of a flapping-wing aircraft, is beneficial to reducing the inertial forces generated by the wing flapping and folding during flight, reducing the sudden changes in the flight posture and speed of the aircraft caused by too large inertial forces, improving the flight stability of the aircraft, reducing the energy consumption of the aircraft, and providing an effective design scheme for the design and improvement of aerodynamic performance of flapping-wing aircrafts of different sizes, especially small flapping-wing aircrafts. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the flapping-wing aircraft in this case,

[0029] Figure 2 It is a schematic structural diagram of the left wing skeleton of the flapping-wing aircraft in this case,

[0030] Figure 3a It is a schematic diagram of the left wing root structure when the wing of the flapping-wing aircraft in this case is fully opened,

[0031] Figure 3b It is a schematic diagram of the left wing root structure when the wing of the flapping-wing aircraft in this case is fully closed,

[0032] Figure 4 It is a schematic diagram of the right drive structure of the flapping-wing aircraft in this case,

[0033] Figure 5 It is a schematic diagram of the left drive structure of the flapping-wing aircraft in this case,

[0034] Figure 6a It is a schematic diagram of the left side of the secondary deceleration group of the flapping-wing aircraft in this case,

[0035] Figure 6b It is a schematic diagram of the right side of the secondary deceleration group of the flapping-wing aircraft in this case,

[0036] Figure 7 It is a schematic diagram of the tail wing structure of the flapping-wing aircraft in this case,

[0037] Figure 8 It is a reference diagram when the wings of the flapping-wing aircraft in this case are horizontally opened,

[0038] Figure 9 It is a reference diagram of the wing rod when the wings of the flapping-wing aircraft in this case are horizontally opened,

[0039] Figure 10 It is a reference diagram when the wings of the flapping-wing aircraft in this case are fully opened,

[0040] Figure 11 It is a reference diagram of the wing rod when the wings of the flapping-wing aircraft in this case are fully opened

[0041] Figure 12 It is a reference diagram when the wings of the flapping-wing aircraft in this case are fully folded,

[0042] Figure 13 It is a reference diagram of the wing rod when the wings of the flapping-wing aircraft in this case are fully folded

[0043] In the figure, 1 is the wing membrane, 2 is the wing rod, 3 is the first wing rod of the wing, 4 is the second wing rod of the wing, 5 is the first outer wing rod, 6 is the second outer wing rod, 7 is the pin, 8 is the first connecting piece, 9 is the second connecting piece, 10 is the third connecting piece, 11 is the rod, 12 is the motor, 13 is the first gear, 14 is the first nut, 15 is the second gear, 16 is the third gear, 17 is the fourth gear, 18 is the fifth gear, 19 is the sixth gear, 20 is the first connecting rod, 21 is the second connecting rod, 22 is the third connecting rod, 23 is the fourth connecting rod, 24 is the second nut, 25 is the first shaft, 26 is the third nut, 27 is the second shaft, 28 is the fourth nut, 29 is the motor base, 30 is the screw, 31 is the fifth nut, 32 is the first tail wing, 33 is the first servo, 34 is the first servo arm, 35 is the first pull rod, 36 is the first rudder angle, 37 is the second servo, 38 is the second tail wing, 39 is the first tail wing rudder surface, 40 is the second servo arm, 41 is the second pull rod, 42 is the second rudder angle, 43 is the second tail wing rudder surface, 44 is the battery, 45 is the left fuselage, 46 is the receiver, 47 is the electronic speed controller, 48 is the right fuselage, 49 is the wing surface support rod, 50 is the fourth connecting piece, 51 is the fifth connecting piece. Detailed implementation mode

[0044] To clearly illustrate the technical features of this patent, the following will elaborate on this patent in detail through specific implementation modes and in combination with its attached drawings.

[0045] As Figures 1-7 shown, the flapping-wing aircraft includes an aircraft fuselage and a pair of foldable wings. The pair of foldable wings are symmetrically arranged on both sides of the aircraft fuselage. The wing includes a connected wing rod 2 and wing membrane 1;

[0046] The bionic wing surface and its folding and flapping structure include a pair of foldable wings and a driving mechanism for the foldable wings; the foldable wings are located on both sides of the flapping-wing aircraft, and the folding change surface is parallel to the wing surface of the wing; the leading edge of the wing membrane is connected to the wing rod and changes with the movement of the wing rod. The folding wings on both sides of the fuselage are symmetrically arranged along the aircraft fuselage, and the synchronous movement of flapping and folding is realized through the driving mechanism located in the front middle of the fuselage;

[0047] The folding mode of the bionic folding wing surface is similar to that of a pigeon's wings during flight, and the shapes are almost the same; when the wing surface is not folded, the maximum wingspan is Amax, when the wing surface is folded, the minimum wingspan is Amin, and the chord length is B. The wing surface folding rate S = (Amax - Amin) / Amax; the folding rate S can be changed by changing the length of the rod in the wing driving mechanism, so as to find the most suitable flight parameters for the aircraft;

[0048] During the flight of the flapping-wing aircraft, the drive mechanism in front of the middle of the fuselage drives the wings to fold and flap. The wings are unfolded during the downstroke of the wings and folded during the upstroke, thereby reducing the resistance generated by the upstroke of the wings during flight; during the flight of the flapping-wing aircraft, the maximum wingspan of the wings can reach 730 mm, and the minimum wingspan can be reduced to about 600 mm.

[0049] The wing rods of the bionic folding wings are arranged in a cross shape and can rotate at the connection. The wing rods are connected to the drive mechanism at the wing root position of the wings; the drive mechanism inputs power through a motor and undergoes two-stage deceleration, and transmits the motion to the wings through a crank-slider mechanism to achieve folding within the wing surface; at the same time, it is transmitted to the wings through a spherical pair and a spherical pin pair mechanism to achieve the flapping of the wings; overall, the folding and flapping motions of the wings are achieved by using the same drive mechanism.

[0050] A flapping-wing aircraft designed by the present invention mainly includes: a drive mechanism, a flapping mechanism, a folding mechanism, a fuselage, a V-shaped tail, and a pair of wings.

[0051] As Figure 4 、 5 、8, 9 show, the fuselage of this flapping-wing aircraft includes a left fuselage 45 and a right fuselage 48. The two fuselages are symmetrically distributed. Drive gears, electronic devices, etc. are distributed on both sides and in the middle of the two fuselages to achieve drive and control. The fuselage is an important carrier of this flapping-wing aircraft. Electronic devices such as a motor mount 29, a motor 12, an electronic speed controller 47, and a receiver 46 are installed on the left fuselage 45. Among them, the motor 12 and the motor mount 29 are fixedly connected to the left fuselage 45 through screws 30 and nuts five 31. The receiver 46 and the electronic speed controller 47 are adhered to the rear side of the right fuselage 48 through Velcro. To balance the mass distribution on both sides of the fuselage of the flapping-wing aircraft, the battery 44 is installed on the left fuselage 45. The battery 44 is adhered to the rear side of the left fuselage 45 through Velcro.

[0052] As shown in Figures 3, 4, and 5, the drive mechanisms of the flapping mechanism and the folding mechanism of this flapping-wing aircraft are gear sets installed on both sides and in the middle of the fuselage. As shown in Figure 6, the gear set consists of gear three 16, gear five 18, gear four 17, gear one 13, gear two 15, and gear six 19, achieving two-stage deceleration with a deceleration ratio of 10. Gear three 16 is fixedly installed on the rotating shaft of the motor 12 and meshes with gear five 18 to achieve the first-stage deceleration. Gear four 17, gear five 18, and gear one 13 are installed on shaft two 27 and fixed by nut one 14 and nut four 28. Gear four 17 and gear one 13 are symmetrically installed on the outer side of the fuselage, and gear five 18 is installed on the inner side of the fuselage, and the rotational speeds of gear one 13, gear four 17, and gear five 18 are the same. Gear one 13 and gear four 17 respectively mesh with gear two 15 and gear six 19 to achieve the second-stage deceleration. Gear six 19 and gear two 15 are installed on shaft one 25 and fixed by nut two 24 and nut three 26.

[0053] The described wing flapping mechanism is mainly installed on both the left and right sides of the fuselage. The lower end of connecting rod two 21 is connected to gear six 19 on the outer side of the left fuselage 45 through a spherical pair, and the upper end of connecting rod two 21 is connected to connecting piece one 8 through a ball pin pair. When gear six 19 rotates driven by the gear reduction group, it will drive connecting rod two 21 to move, thereby driving connecting piece one 8 to rotate up and down around the rod. The flapping mechanism on the right side of the fuselage consists of gear two 15, connecting rod four 23, and connecting pieces, etc., which is symmetrically arranged with the flapping mechanism on the left side of the fuselage and has the same motion mode, so it will not be elaborated in detail. The flapping mechanism of this flapping-wing aircraft is a spatial mechanism, which cleverly converts the motion parallel to the fuselage direction of the aircraft into the motion perpendicular to the fuselage direction.

[0054] The described wing folding drive mechanism is mainly installed on both the left and right sides of the fuselage, behind the flapping mechanism. The lower end of connecting rod one 20 is installed on gear six 19 on the outer side of the left fuselage 45 through a rotating pair, and the upper end of connecting rod one 20 is connected to connecting piece three 10 through a rotating pair. Connecting piece three 10 is slidably connected to rod 11 and can slide relatively. Gear six 19, connecting rod one 20, connecting piece three 10, and rod 11 form a crank-slider structure. When gear six 19 rotates, connecting rod one 20 starts to move, pushing connecting piece three 10 to slide along rod 11, thereby driving connecting piece two 9 to move. Connecting piece two 9 drives the angles of wing rod one 3 and wing rod two 4 to change, ultimately realizing the folding of the wings. The folding drive mechanism on the right side of the fuselage consists of gear two 15, connecting rod three 22, and connecting pieces, etc., which is symmetrically arranged with the folding drive mechanism on the left side of the fuselage and has the same motion mode, so it will not be elaborated in detail. The wing folding drive mechanism is a planar structure and shares a prime mover with the wing flapping mechanism, solving the problem of adding more mass to the aircraft due to the need to add a prime mover.

[0055] As Figure 2As shown in the figure, the wing folding structure is mainly composed of wing rods symmetrically distributed on both sides, with four wing rods on each of the left and right sides. Taking the left half of the wing as an example, the left wing is mainly composed of wing rod 1-3, wing rod 2-4, outer wing rod 1-5, outer wing rod 2-6, and multiple pins 7. Wing rod 1-3 and wing rod 2-4, wing rod 2-4 and outer wing rod 1-5, and wing rod 1-3 and outer wing rod 2-6 are all connected by the same pins as pin 7. The wing rods below are in interference fit with the pins, and the wing rods above are in clearance fit with the pins to ensure free rotation at each connection. When the connecting piece 2-9 moves, it will push the angles of wing rod 1-3 and wing rod 2-4 to change. When the angles of wing rod 1-3 and wing rod 2-4 become larger, the wing starts to fold, and when the angles become smaller, the wing starts to unfold. The right half of the wing has the same structure and motion as the left half of the fuselage. The left and right parts of the wing are symmetrically distributed on both sides of the fuselage, and the right half of the wing will not be elaborated in detail.

[0056] Adopting the described wing structure to completely imitate the three-segment wing skeleton of flying birds is beneficial to improving the aerodynamic characteristics of the flapping-wing aircraft.

[0057] The wing membrane 1 of the described wing is an ultra-thin TPU soft film, which is pasted on the leading edges of the wing rods on both sides. It folds and unfolds as the structure of the wing rods changes. It is light in weight, beneficial for the aircraft to carry, has good flexibility, and is easy to fold.

[0058] As Figure 7 As shown in the figure, the tail wing of the described flapping-wing aircraft adopts a V-shaped tail wing, which includes a tail wing, a servo, a tail wing control surface, a pull rod, a control angle, etc. Taking the left side of the entire tail wing as an example, servo 1-33 is installed parallel inside tail wing 1-32. Servo 1-33 drives pull rod 1-35 through servo arm 1-34 to drive control angle 1-36 fixedly installed on tail wing control surface 2-43 to make tail wing control surface 2-43 rotate relative to tail wing 1-32. The right side of the tail wing composed of tail wing 2-38, servo 2-37, servo arm 2-40, pull rod 2-41, control angle 2-42, and tail wing control surface 1-39 has the same structure and motion as the left side of the tail wing, and will not be elaborated in detail. The entire tail wing is symmetrically distributed on both sides of the fuselage, and the turning of the flapping-wing aircraft is achieved by changing the angle of the tail wing control surface through the servo.

[0059] The control of the bionic wing surface and its folding and flapping structure of the described flapping-wing aircraft is mainly carried out by the pilot controlling the speed of the motor through the remote control. The specific implementation method is as follows: The pilot of the aircraft transmits a 2.4G signal through the remote control, and the on-board receiver 46 receives the signal and converts it into a PWM wave signal to input to the electronic speed controller 47 to control the speed of the motor 12. The flapping frequency and folding frequency of the folding wing are changed according to the speed of the motor. The tail wing servo is also controlled by the signal transmitted by the pilot through the remote control and converted into a PWM wave by the receiver 46, and finally the turning of the aircraft is controlled.

[0060] The overall movement of the wings of the flapping-wing aircraft is that the gear drives the flapping mechanism and the folding mechanism to move. When the wing flaps downwards, the folding mechanism of the wing will gradually unfold the wing surface to increase the lift generated by its flapping. When the wing flaps upwards, the folding mechanism of the wing will gradually fold the wing surface to reduce the resistance generated by its flapping, thereby improving the aerodynamic performance of the flapping-wing aircraft. The folding and flapping mechanisms can cooperate well in motion by using the same driving element.

[0061] Figures 8 to 13 These are the postures of the wing membrane and wing rod of this flapping-wing aircraft wing in the fully open, horizontally open, and fully folded conditions. Taking this flapping-wing aircraft as an example, when it is fully open, the wingspan Amax of its wing is 730 mm, and when it is fully folded, the wingspan Amin of its wing is about 600 mm, and the folding rate S is about 18.5%. Changing the length of the wing rod or the length of the rod in the folding drive can change the maximum and minimum wingspans of its wing, so as to adapt to flapping-wing aircraft of different sizes and with different aerodynamic characteristics.

[0062] Taking this flapping-wing aircraft as an example, when its wing flaps upwards, the maximum limit angle between the wing and the horizontal plane is 70°. Compared with existing flapping-wing aircraft, the range of the upward flapping angle that this flapping-wing aircraft can reach is wider. Its flapping angle can be changed by changing the lengths of the connecting rod four 23 and the connecting rod two 21 in the flapping mechanism, so as to find the best aerodynamic performance of flapping-wing aircraft of different sizes.

[0063] In the wing surface folding and flapping structure of this flapping-wing aircraft, rigid components mostly adopt carbon fiber materials. Carbon fiber materials have high strength, light weight, low price, and are easy to obtain, which is beneficial to reducing the mass of the flapping-wing aircraft, reducing the inertial moment generated by the flapping of its wings, reducing the manufacturing cost of the flapping-wing aircraft, and providing more convenience for the flapping-wing aircraft to carry more electronic devices (such as: video transmission devices, GPS, etc.).

[0064] Generally speaking, the bionic wing surface and its folding and flapping structure of this flapping-wing aircraft are mainly used to help improve the aerodynamic performance of flapping-wing aircraft of different sizes. Its structure is simple, light in weight, easy to move, low in cost, simple to control, and has strong applicability to flapping-wing aircraft of different sizes.

[0065] There are many specific implementation ways of the present invention. The above description is only the preferred implementation manner of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements can still be made, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. A bionic wing surface and its folding and flapping structure of a flapping-wing aircraft. The bionic flapping-wing aircraft includes a fuselage, a pair of folding wings, and a V-shaped tail. The pair of folding wings and the V-shaped tail are symmetrically distributed on both sides of the fuselage of the flapping-wing aircraft. It is characterized in that the folding wing includes a wing rod (2) connected to the fuselage and a wing membrane (1) connected to the wing rod (2); the wing rod (2) includes a first wing rod (3), a second wing rod (4), a first outer wing rod (5), and a second outer wing rod (6). The middle parts of the first wing rod (3) and the second wing rod (4) are hinged. The root of the second outer wing rod (6) is hinged to the first wing rod (3). The two ends of the first outer wing rod (5) are respectively hinged to the second wing rod (4) and the second outer wing rod (6), so that a rhombus is formed among the first wing rod (3), the second wing rod (4), the first outer wing rod (5), and the second outer wing rod (6). The folding movement of the wing is realized by a simple structure, the weight brought by the folding wing structure is reduced, and thus the inertial force generated during the wing movement is reduced; a first connecting piece (8) that can be turned up and down is hinged on the fuselage. The root of the second wing rod (4) is hinged to the first connecting piece (8), and the second wing rod (4) can swing back and forth relative to the first connecting piece (8); a rod member (11) arranged along its length direction is fixedly connected to the fuselage. A third connecting piece (10) that is slidably connected to the rod member (11) is sleeved on the rod member (11). A second connecting piece (9) that can be turned up and down is hinged on the third connecting piece (10). The root of the first wing rod (3) is hinged to the second connecting piece (9), and the first wing rod (3) can swing back and forth relative to the second connecting piece (9); the bionic flapping-wing aircraft further includes a motor (12) fixedly installed on the fuselage, a sixth gear (19) kept in linkage with the motor (12), a second connecting rod (21) connected between the sixth gear (19) and the second wing rod (4), and a first connecting rod (20) connected between the sixth gear (19) and the third connecting piece (10), so as to complete the flapping and folding movements by using the same driving element; the sixth gear (19) is arranged perpendicular to the length direction of the fuselage, and its center is rotatably connected to the fuselage. One end of the second connecting rod (21) is movably connected to the surface of the sixth gear (19) through a spherical hinge, and the other end is movably connected to the first connecting piece (8) through a ball pin hinge. The two ends of the first connecting rod (20) are directly hinged to the surface of the sixth gear (19) and the third connecting piece (10).

2. The bionic wing surface and its folding and flapping structure of a flapping-wing aircraft according to claim 1, characterized in that, The wing membrane (1) is an ultra-thin tpu soft membrane. The leading edge of the wing membrane (1) is pasted on the leading edge of the wing rod (2), and it folds and unfolds as the structure of the wing rod changes; The front edge of the wing membrane (1) is respectively pasted from the inside to the outside on the parts of the second wing rod (4), the first wing rod (3), and the second outer wing rod (6) that are located at the front edge of the wing rod. Below the wing rod (2), there are also installed a wing surface support rod (49), a fourth connecting piece (50), and a fifth connecting piece (51) for fixing the wing surface. One end of the wing surface support rod (49) is simultaneously hinged to the first wing rod (3) and the second outer wing rod (6), and the other end is fixedly connected to the wing membrane (1). The fourth connecting piece (50) is simultaneously hinged to the second wing rod (4) and the first outer wing rod (5). The wing surface support rod (49) passes through the fourth connecting piece (50) and is slidably connected to it.

3. The biomimetic wing surface and its folding and flapping structure of a flapping-wing aircraft according to claim 1, characterized in that, The motor (12) and the sixth gear (19) are kept in linkage through a two-stage reduction transmission mechanism. The two-stage reduction transmission mechanism includes a third gear (16), a fourth gear (17), a fifth gear (18), and a sixth gear (19). The third gear (16) is fixedly connected to the output shaft of the motor (12) and meshes with the fifth gear (18) to achieve the first-stage reduction. The fourth gear (17) and the fifth gear (18) that are rotatably connected to the fuselage are coaxial and fixedly connected to each other, and the fourth gear (17) meshes with the sixth gear (19) to achieve the second-stage reduction.

4. The bionic wing surface and its folding and flapping structure of a flapping-wing aircraft according to claim 1, characterized in that, The speed of the motor (12) is controlled by an electronic speed controller (47). The electronic speed controller (47) inputs the received control signal through a receiver (46). The motor (12), the electronic speed controller (47), and the receiver (46) are all powered by a battery (44). The motor (12), the electronic speed controller (47), and the receiver (46) are fixedly arranged on one side of the fuselage, and the battery (44) is arranged on the other side of the fuselage.

5. The biomimetic wing surface and its folding and flapping structure of a flapping-wing aircraft according to claim 4, characterized in that, The V-shaped tail is composed of a pair of tail wings. A tail wing rudder surface is hinged to the tail of the tail wing, and a servo for driving the tail wing rudder surface is provided on the tail wing. The servo is also connected to the receiver.

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