A micro air vehicle low-speed high-lift corrugated airfoil and design method

Abstract

The present application relates to a kind of micro aircraft low-speed lift increasing wrinkle airfoil, including main wing, wind speed detection sensor, shape memory alloy wire, direct current power supply, remote control machine, the main wing is the wrinkle wing profile structure with lift increasing effect, the wind speed detection sensor is installed on main wing and the wind speed signal detected is passed to remote control machine, the shape memory alloy wire is electrically connected with direct current power supply, the shape memory alloy wire and direct current power supply are installed on main wing, the direct current power supply is connected with remote control machine and is controlled by remote control machine, the on-off electricity situation of shape memory alloy wire and direct current power supply is controlled by remote control machine, make main wing switch between wrinkle wing type and flat plate wing type.The present application can significantly improve the lift of micro aircraft wing, has the advantages such as controllable deformation, reliable structure, stable driving and low energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of aircraft design, specifically relating to a low-speed lift-enhancing folded airfoil for micro-sized aircraft and its design method. Background Technology

[0002] Miniature aircraft (MAVs) typically refer to palm-sized aircraft, with a maximum size of approximately 10.

[0003] cm, the typical flight chord length Reynolds number (hereinafter referred to as Reynolds number) is 10. 4 ~10 5 It has great application value in both military and civilian fields; in recent years, as MAVs have become increasingly miniaturized, their flight Reynolds number range can reach 10. 2 ~10 5 At such low Reynolds numbers, traditional streamlined airfoils are often affected by viscous factors, resulting in premature laminar separation and severe nonlinear effects, leading to phenomena such as decreased lift, increased drag, and smaller stall angle of attack.

[0004] In both civilian and military fields, the endurance and flight capabilities of micro-aircraft (MAVs) are of paramount concern. Under the same operating conditions, airfoils with higher lift coefficients can fly farther with the same energy consumption, while airfoils with larger stall angles of attack offer better flight stability. However, the significant differences in airfoil chord length and Reynolds number mean that aerodynamic design principles applicable to traditional "macroscale" aircraft may no longer be suitable for MAVs. Traditional streamlined airfoils with smooth surfaces do not necessarily provide MAVs with good flight performance. Exploring airfoil structures with better flight performance suitable for micro-aircraft has become a new trend.

[0005] The performance of airfoils with smooth surfaces and those with rough surfaces differs at different Reynolds numbers, particularly below 1000. 5 At certain times, airfoils with rough surfaces exhibit a higher lift-to-drag ratio. This suggests that within the Reynolds number range of MAV flight, airfoils with rough surfaces can be used in MAV design, while traditional streamlined airfoils can be used beyond the advantageous Reynolds number range of rough-surface airfoils. Domestic research on MAV airfoils is not yet comprehensive. While some corrugated airfoils have been proposed, no practically feasible airfoil structures that can bring aerodynamic gains to MAVs have been identified. Furthermore, there is limited research exploring the differences in flight performance at different Reynolds numbers within the MAV's flight chord length range. Therefore, to improve the flight performance of MAVs, exploring airfoil structures that can enhance lift across the entire flight chord length Reynolds number range of micro-aircraft is particularly important. Summary of the Invention

[0006] To overcome the shortcomings of traditional airfoils used in micro-aircraft, this invention proposes a deformable airfoil structure suitable for micro-aircraft, which improves the flight capability of micro-aircraft across its entire Reynolds number range while meeting the basic performance requirements of airfoil structures.

[0007] To overcome the aforementioned technical difficulties, this invention proposes a deformable folded airfoil structure based on a biomimetic dragonfly wing and driven by shape memory alloy wires. Through research on dragonfly wings and computational fluid dynamics simulation, a folded airfoil structure with a higher lift coefficient and larger stall angle of attack than traditional airfoils is derived at lower Reynolds numbers for micro-aircraft. Furthermore, by combining shape memory alloy wires, it is proposed to transform the folded airfoil into a flat wing at higher Reynolds numbers, thereby improving the disadvantage of the folded wing's decreased flight performance at high Reynolds numbers. This results in the airfoil exhibiting good flight performance across the entire Reynolds number range for micro-aircraft.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A low-speed lift-enhancing folded airfoil for a micro-sized aircraft includes a main wing, a wind speed sensor, a shape memory alloy wire, a DC power supply, and a remote controller. The main wing has a folded wing shape structure with a lift-enhancing effect. The wind speed sensor is mounted on the main wing and transmits the detected wind speed signal to the remote controller. The shape memory alloy wire is electrically connected to the DC power supply. The shape memory alloy wire and the DC power supply are mounted on the main wing. The DC power supply is connected to and controlled by the remote controller. The remote controller controls the on / off state of the DC power supply and the shape memory alloy wire, allowing the main wing to switch between a folded airfoil and a flat airfoil.

[0010] When the wind speed does not exceed the set value, the remote control will control the DC power supply to not be energized, the shape memory alloy wire will be in a folded and bent state at natural temperature, and the main wing will be in a folded airfoil state.

[0011] When the wind speed exceeds the set value, the remote control controls the DC power supply to turn on, the shape memory alloy wire is in a straight state under the power heating, and the main wing is in a flat airfoil state.

[0012] Furthermore, the main wing is made of rubber material, which not only ensures the rigidity and stability of the wing, but also allows it to be deformed by shape memory alloy wires.

[0013] Furthermore, the folded wing has a flat airfoil chord length of c, an airfoil thickness of 3%c, two folds, a fold apex angle of 120°, and a trailing edge with a gently sloping fold apex angle of 160°.

[0014] Furthermore, holes corresponding to the number of shape memory alloy wires are pre-drilled at equal intervals along the span of the main wing from the leading edge to the trailing edge of the airfoil. The diameter of the holes is slightly smaller than the diameter of the shape memory alloy wires. The shape memory alloy wires are installed into the holes using an interference fit. Small triangular openings are made on the lower surface of the wing at folds in the chord direction to facilitate the bending of the airfoil during deformation.

[0015] Furthermore, there are 9 shape memory alloy wires, and 9 holes are equidistantly reserved along the span of the main wing from the leading edge to the trailing edge of the airfoil.

[0016] A design method for a low-speed lift-enhancing folded airfoil for a micro-aircraft includes the following steps:

[0017] (1) Based on the characteristics of bionic folded airfoils, airfoils with different numbers of folds have different lift coefficients. By adding different numbers of folds of the same size from the leading edge to half chord length of the airfoil, the shape structure with the highest lift coefficient among different numbers of folds can be obtained.

[0018] (2) After obtaining the first shape structure in the first step, change the fold vertex angle to change the fold amplitude and span, and obtain the second shape structure with the fold angle that has the highest lift coefficient.

[0019] (3) After obtaining the second shape structure, according to the characteristics of the dragonfly wing shape structure, add relatively gentle folds at the trailing edge of the airfoil to obtain the final airfoil structure.

[0020] The order of the two steps mentioned above can be interchanged.

[0021] A method for modifying a low-speed lift-enhancing folded airfoil for a micro-aircraft includes the following steps:

[0022] (1) At low temperature, the shape memory alloy wire is bent into the shape of a folded wing, and at high temperature it is stretched into a straight line; at natural temperature without electricity, the shape memory alloy wire is in a folded bent state, and after being heated by electricity, it becomes a flat straight state.

[0023] (2) The main wing is made of rubber material, which not only ensures the rigidity and stability of the wing, but also allows it to be deformed by shape memory alloy wire. When the main wing is in the state of a flat airfoil, a high-temperature straight shape memory alloy wire is placed into the reserved hole. After cooling, the wing becomes wrinkled along with the alloy wire.

[0024] (3) During the flight of the micro aircraft with low-speed lift-enhancing folded airfoil driven by shape memory alloy wire, the wind speed detection sensor senses the external wind speed. When the wind speed is greater than the set value, the signal is transmitted to the remote controller, so that the DC power supply is manually turned on to make the folded airfoil become a flat airfoil. When the wind speed is lower than the set speed, the power supply is manually turned off, and the flat airfoil becomes a folded airfoil again.

[0025] Operating Method: While pleated airfoils offer better flight performance than flat airfoils at low speeds, flat airfoils exhibit greater stability as flight speed increases. A main wing equipped with deformable pleated wings, in its pleated form at lower speeds, possesses a higher lift coefficient and a larger stall angle of attack than traditional flat airfoils. Wind speed sensors on the wing detect external wind speed. When the wind speed (flight speed) exceeds a set value (the maximum flight speed at which pleated wings outperform flat airfoils), a signal is transmitted to the remote controller. This manually energizes a current generator, causing nine identical shape memory alloy wires connected in series to heat up and rapidly straighten simultaneously, transforming the pleated wings into flat airfoils. This mitigates the instability of pleated wings at high chord Reynolds numbers. When the wind speed falls below the set value, the power is manually disconnected, and the shape memory alloy wires return to their pleated state, transforming the flat airfoil back into a pleated wing.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] 1. The folded wing airfoil proposed in this invention has a significantly improved lift coefficient compared to the traditional flat wing used in micro aircraft, which can be improved by up to 50% within the calculated Reynolds number range;

[0028] 2. Compared with the traditional flat wings used in micro aircraft, the folded wing airfoil of this invention has a larger stall angle of attack at a lower flight chord Reynolds number, which can improve the flight capability of micro aircraft;

[0029] 3. This invention uses shape memory alloy for driving, which has a simple driving principle and utilizes its shape memory effect to ensure efficient and stable deformation.

[0030] 4. At low Reynolds numbers, folded wings have higher lift coefficients and stall angles of attack, while at higher Reynolds numbers, flat wings have more stable flight performance. Having two types of wings can ensure that micro-aircraft have good flight performance throughout their entire Reynolds number range. Attached Figure Description

[0031] Figure 1 A flat airfoil is used in a low-speed lift-enhancing folded airfoil design and deformable drive scheme for a micro-small aircraft.

[0032] Figure 2 The deformed folded airfoil is designed for a low-speed lift-enhancing folded airfoil scheme for a micro-small aircraft;

[0033] Figure 3 This is a schematic diagram of the flat airfoil structure proposed in this invention;

[0034] Figure 4 This is a schematic diagram of the folded airfoil structure proposed in this invention;

[0035] Figure 5 for Figure 4 Add dimension markings;

[0036] Figure 6 The diagram shows the lift lines of the folded airfoil proposed in this invention and the traditional flat airfoil at different Reynolds numbers.

[0037] Figure 7 This diagram illustrates how the lift coefficient varies with Reynolds number when using deformable folded wings and non-deformable folded wings and flat wings at two sets of identical flight angles of attack.

[0038] In the diagram: 1. Main wing, 2. Wind speed sensor, 3. Shape memory alloy wire, 4. DC power supply. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0040] A low-speed lift-enhancing folded airfoil for a micro-sized aircraft includes a main wing 1, a wind speed sensor 2, a shape memory alloy wire 3, a DC power supply 4, and a remote controller (not shown in the figure). The main wing 1 has a folded wing shape structure with a lift-enhancing effect. The wind speed sensor 2 is mounted on the main wing 1 and transmits the detected wind speed signal to the remote controller. The shape memory alloy wire 3 is electrically connected to the DC power supply 4. The shape memory alloy wire 3 and the DC power supply 4 are mounted on the main wing 1. The DC power supply 4 is connected to and controlled by the remote controller. The remote controller controls the on / off state of the DC power supply 4 and the shape memory alloy wire 3, so that the main wing 1 can switch between a folded airfoil and a flat airfoil.

[0041] When the wind speed does not exceed the set value, the remote control controls the DC power supply 4 to not be powered on, the shape memory alloy wire 3 is in a folded and bent state at natural temperature, and the main wing 1 is in a folded airfoil state.

[0042] When the wind speed exceeds the set value, the remote control controls the DC power supply 4 to turn on, the shape memory alloy wire 3 is in a straight state under the power heating, and the main wing 1 is in a flat airfoil state.

[0043] Furthermore, the main wing 1 is made of rubber material (hardness 90A), which not only ensures the rigidity and stability of the wing, but also allows it to be deformed by shape memory alloy wire 3.

[0044] Furthermore, the folded wing has a flat airfoil chord length of c, an airfoil thickness of 3%c, two folds, a fold apex angle of 120°, and a trailing edge with a gently sloping fold apex angle of 160°.

[0045] Furthermore, the main wing 1 has holes pre-drilled along the spanwise direction at equal intervals, corresponding to the number of shape memory alloy wires 3, from the leading edge to the trailing edge of the airfoil. The diameter of the holes is slightly smaller than the diameter of the shape memory alloy wires 3. The shape memory alloy wires 3 are installed into the holes using an interference fit. Small triangular openings are made on the lower surface of the wing in the chord direction where there are wrinkles, to facilitate the bending of the airfoil during deformation.

[0046] Furthermore, there are 9 shape memory alloy wires 3, and 9 holes are equidistantly reserved along the span of the main wing 1 from the leading edge to the trailing edge of the airfoil.

[0047] A design method for a low-speed lift-enhancing folded airfoil for a micro-aircraft includes the following steps:

[0048] (1) Based on the characteristics of bionic folded airfoils, airfoils with different numbers of folds have different lift coefficients. By adding different numbers of folds of the same size from the leading edge to half chord length of the airfoil, the shape structure with the highest lift coefficient among different numbers of folds can be obtained.

[0049] (2) After obtaining the first shape structure in the first step, change the fold vertex angle to change the fold amplitude and span, and obtain the second shape structure with the fold angle that has the highest lift coefficient.

[0050] (3) After obtaining the second shape structure, according to the characteristics of the dragonfly wing shape structure, add relatively gentle folds at the trailing edge of the airfoil to obtain the final airfoil structure.

[0051] The order of steps 1 and 2 can be interchanged.

[0052] A method for modifying a low-speed lift-enhancing folded airfoil for a micro-aircraft includes the following steps:

[0053] (1) At low temperature, the shape memory alloy wire 3 is bent into the shape of a folded wing, and at high temperature it is stretched into a straight line; at natural temperature without electricity, the shape memory alloy wire 3 is in a folded bent state, and after being heated by electricity, it becomes a flat straight state.

[0054] (2) The main wing 1 is made of rubber material, which not only ensures the rigidity and stability of the wing, but also allows it to be deformed by shape memory alloy wire. When the main wing 1 is in the state of a flat airfoil, a high-temperature straight shape memory alloy wire 3 is placed into the reserved hole. After cooling, the wing becomes wrinkled along with the alloy wire.

[0055] (3) During the flight of the micro-aircraft with low-speed lift-enhancing folded airfoil driven by shape memory alloy wire 3, the wind speed detection sensor 2 senses the external wind speed. When the wind speed is greater than the set value, the signal is transmitted to the remote controller, so that the DC power supply 4 is remotely powered on, and the folded airfoil becomes a flat airfoil. When the wind speed is lower than the set speed, the power supply is manually disconnected, and the flat airfoil becomes a folded airfoil again.

[0056] Operating Method: While pleated airfoils offer better flight performance than flat airfoils at low speeds, flat airfoils exhibit greater stability as flight speed increases. A main wing equipped with deformable pleated wings, in its pleated form at lower speeds, possesses a higher lift coefficient and a larger stall angle of attack than traditional flat airfoils. Wind speed sensors on the wing detect external wind speed. When the wind speed (flight speed) exceeds a set value (the maximum flight speed at which pleated wings outperform flat airfoils), a signal is transmitted to the remote controller. This manually energizes a current generator, causing nine identical shape memory alloy wires connected in series to heat up and rapidly straighten simultaneously, transforming the pleated wings into flat airfoils. This mitigates the instability of pleated wings at high chord Reynolds numbers. When the wind speed falls below the set value, the power is manually disconnected, and the shape memory alloy wires return to their pleated state, transforming the flat airfoil back into a pleated wing.

[0057] Following the above technical solutions, such as Figures 1 to 5 As shown in the figure, this embodiment presents a low-speed lift-enhancing folded airfoil design and deformation drive scheme for micro-aircraft, which brings higher lift and a larger stall angle of attack to micro-aircraft throughout its entire flight chord Reynolds number range.

[0058] This invention discloses a deformable biomimetic pleated wing airfoil structure driven by shape memory alloy wires, comprising a deformable pleated wing shape structure, a wind speed detection sensor, and nine shape memory alloy wires. The airfoil has two modes: flat and pleated. In the flat mode, nine holes are pre-drilled at equal intervals along the span of the main wing, extending from the leading edge to the trailing edge. The hole diameter is slightly smaller than the diameter of the shape memory alloy wires. The shape memory alloy wires are installed into the holes using an interference fit. Small triangular openings are made on the lower surface of the wing at the pleated locations along the chord direction to facilitate bending of the airfoil during deformation. At low temperatures, the nine shape memory alloy wires are bent into the shape of a pleated wing; at high temperatures, they are stretched into straight lines. At ambient temperature without electricity, the alloy wires are in a pleated, bent state; after being heated, they become flat and straight. To facilitate the installation of the shape memory alloy wires into the wing, the hot, straight shape memory alloy wires are placed into the pre-drilled openings in the flat state. After cooling, the wing transforms into a pleated shape along with the alloy wires. Nine alloy wires are connected in series and fed into a power source mounted on the fuselage. The wings are made of rubber (90A hardness) material, ensuring both wing rigidity and flight stability, and also allowing them to deform via shape memory alloy wires. Figure 1 The image shows a flat airfoil after the alloy wire has been installed. When powered on, it can be converted into... Figure 2 The folded airfoil shown.

[0059] Figure 3 This is a schematic diagram of the flat airfoil structure in the deformable wing of the present invention. The chord length of the flat airfoil is 50 mm, and the airfoil thickness is 3% of the chord length.

[0060] Figure 4 This is a schematic diagram of the folded airfoil structure proposed in this invention. Calculations show that the airfoil with 2 folds, a fold vertex angle of 120°, and a trailing edge with a gentle fold vertex angle of 160° has the largest lift coefficient. In this schematic diagram, the folded chord length after deformation from a flat airfoil with a chord length of 50mm is 47.02mm. Figure 5 The dimensions of the folded wing are shown.

[0061] Figure 6The diagrams illustrating the lift curves of the proposed folded airfoil and the traditional flat airfoil at different Reynolds numbers are presented here. The Reynolds numbers are divided into two groups: one for 1000 / 5000 / 10000, and the other for 50000 / 100000. In the first group of lower Reynolds number examples, it is clearly observed that the stall angle of attack of the folded airfoil is 2-3° larger than that of the flat airfoil. In the higher Reynolds number examples, the flat airfoil has a larger stall angle of attack. Particularly noteworthy is that at a chord length Reynolds number of 100000, the lift and drag calculations for the folded airfoil only show 0-9°. As the angle of attack continues to increase, the calculations begin to fail to converge, and no steady-state results can be obtained. The unsteady aerodynamic calculations of the folded airfoil show that, due to the continuous generation and shedding of vortices, its lift and drag fluctuate greatly, and the lift exhibits non-periodic changes. At this point, it is difficult for the folded airfoil to generate a stable flow field. However, across all calculated Reynolds numbers and angles of attack, the lift coefficient of the folded airfoil is consistently greater than that of the flat airfoil. At a Reynolds number of 10,000 and an angle of attack of 10°, the lift coefficient of a folded wing is 50% greater than that of a flat wing. However, at a Reynolds number of 100,000, considering both the magnitude of the lift coefficient and the lift line, the advantage of the folded wing is no longer significant. Therefore, this invention proposes the idea of ​​converting the folded wing into a flat wing as the Reynolds number increases.

[0062] Figure 7 This diagram illustrates the variation of lift coefficient with Reynolds number for morphing folded wings, non-morphing folded wings, and flat wings at the same angle of attack. It shows that at an angle of attack of 13°, once the Reynolds number exceeds 50,000, the lift coefficient of the flat airfoil begins to exceed that of the folded wing. More importantly, however, as the Reynolds number increases, the folded wing can no longer generate a stable flow field, and flight becomes unstable. In other words, at lower Reynolds numbers, folded wings perform better, while at higher Reynolds numbers, flat wings offer better performance.

[0063] The working process of this invention is as follows:

[0064] The main wing of the micro-aircraft equipped with the aforementioned deformable biomimetic folded wing airfoil structure driven by shape memory alloy wires exhibits a higher lift coefficient and a larger stall angle of attack than traditional flat airfoils during low-speed flight, thanks to its folded shape. A wind speed sensor on the wing detects the external wind speed. When the wind speed (flight speed) exceeds a set value, a signal is transmitted to the remote controller, which then manually energizes a current generator. Nine shape memory alloy wires of the same size and length, connected in series, heat up and rapidly straighten simultaneously, transforming the folded wing into a flat wing. This mitigates the instability of folded wings at high chord Reynolds numbers. When the wind speed falls below the set speed, the power is manually disconnected, causing the alloy wires to fold back into their folded state, transforming the flat wing back into a folded wing. Note: In this calculation, the set speed is 14.6 m / s at a Reynolds number of 50,000. This speed may vary depending on the operating conditions and airfoil type.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-speed lift-enhancing folded airfoil for micro-sized aircraft, characterized in that, The system includes a main wing (1), a wind speed sensor (2), a shape memory alloy wire (3), a DC power supply (4), and a remote control. The main wing (1) has a pleated wing shape with a lift-enhancing effect. The wind speed sensor (2) is mounted on the main wing (1) and transmits the detected wind speed signal to the remote control. The shape memory alloy wire (3) is electrically connected to the DC power supply (4). The shape memory alloy wire (3) and the DC power supply (4) are mounted on the main wing (1). The DC power supply (4) is connected to and controlled by the remote control. The remote control controls the on / off state of the DC power supply (4) and the shape memory alloy wire (3), causing the main wing (1) to switch between a pleated airfoil and a flat airfoil. When the wind speed does not exceed the set value, the remote control controls the DC power supply (4) to be de-energized, the shape memory alloy wire (3) is in a pleated bent state at natural temperature, and the main wing (1) is in a pleated airfoil state. When the wind speed exceeds the set value, the remote control controls the DC power supply (4) to be energized, the shape memory alloy wire (3) is in a straight state under energized heating, and the main wing (1) is in a flat airfoil state. The main wing (1) is made of rubber material; the main wing (1) has holes along the spanwise equidistantly reserved from the leading edge to the trailing edge of the airfoil corresponding to the number of shape memory alloy wires (3), the hole diameter is slightly smaller than the diameter of the shape memory alloy wires (3), and the shape memory alloy wires (3) are installed into the holes by interference fit. Small triangular openings are made on the lower surface of the wing in the chord direction where there are wrinkles; there are 9 shape memory alloy wires (3), and the main wing (1) has 9 holes along the spanwise equidistantly reserved from the leading edge to the trailing edge of the airfoil.

2. The low-speed lift-enhancing folded airfoil for micro-sized aircraft according to claim 1, characterized in that, The main wing (1) has a flat airfoil chord length of c, an airfoil thickness of 3%c, a number of folds of 2, a fold vertex angle of 120°, and a trailing edge gentle fold vertex angle of 160°.

3. A design method for a low-speed lift-enhancing folded airfoil for a micro-sized aircraft as described in claim 1 or 2, characterized in that, include: Step (1): Based on the characteristics of biomimetic folded airfoils, airfoils with different numbers of folds have different lift coefficients. Add different numbers of folds of the same size to the leading edge of the airfoil to half chord length to obtain the shape structure with the highest lift coefficient among different numbers of folds. Step (2): Change the angle of the fold apex, thereby changing the fold amplitude and span, and obtain the fold angle shape structure with the highest lift coefficient. Step (3): Based on the structural characteristics of dragonfly wings, add gentle folds to the trailing edge of the airfoil to obtain the final airfoil structure. The order of steps (1) and (2) can be interchanged.

4. A method for modifying the low-speed lift-enhancing folded airfoil of a micro-sized aircraft as described in claim 1 or 2, characterized in that, include: Step (1): At low temperature, the shape memory alloy wire (3) is bent into the shape of a pleated wing, and at high temperature it is stretched into a straight line; at natural temperature without electricity, the shape memory alloy wire (3) is in a pleated bent state, and after being heated by electricity, it becomes a flat straight state. Step (2): The main wing (1) is made of rubber material; while the main wing (1) is in the state of a flat airfoil, a high-temperature straight shape memory alloy wire (3) is placed into the reserved hole. After cooling, the main wing becomes wrinkled along with the shape memory alloy wire. Step (3): Install the micro-aircraft driven by shape memory alloy wire (3) during the flight of the micro-aircraft with low-speed lift-enhancing folded airfoil. The wind speed detection sensor (2) senses the external wind speed. When the wind speed is greater than the set value, the signal is transmitted to the remote control, so that the DC power supply (4) is remotely powered on, so that the folded airfoil becomes a flat airfoil. When the wind speed is lower than the set speed, the power supply is manually disconnected, and the flat airfoil becomes a folded airfoil again.

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