Tailstock type tailless layout amphibious aircraft adopting foldable wings and design method

Abstract

The invention provides a tailstock type tailless layout amphibious aircraft adopting foldable wings and a design method, and relates to the field of amphibious aircraft design. According to the invention, aiming at a tailless-layout tailstock-type amphibious aircraft, by designing a foldable wing mechanism, the wings are unfolded to keep a high aspect ratio layout during air cruise, and the wings are folded to form an envelope layout for a fuselage during water surface dwelling and stopping; therefore, the aerodynamic performance requirement of the tailless layout tailstock type amphibious aircraft in an air cruising mode and the requirement of the tailless layout tailstock type amphibious aircraft in a water surface dwelling mode for the gravity center stabilizing distance and the floating stability are met, and the tailless layout tailstock type amphibious aircraft can take off quickly under the high sea condition. The problems that the relative positions of the gravity center, the pneumatic focus and the stable center of a traditional tailstock type fixed wing aircraft in the water surface floating state and the air cruising flight state are difficult to design, and the stability of the aircraft in the water surface floating state is difficult to guarantee through a traditional layout design are solved.

Description

Technical Field

[0001] The invention relates to the field of amphibious aircraft design, in particular to a tail-seat type tailless layout amphibious aircraft with foldable wings and a design method. Background Art

[0002] In applications such as maritime inspection, search, environmental monitoring, and relay communications, large fixed-wing aircraft are currently commonly used to drop payload nodes in the target sea area. However, the target sea area may have factors such as bad weather and unknown risks, which bring great risks to large fixed-wing aircraft in performing tasks in the air. If amphibious multi-modal drones can be used to fly directly to the target sea area, land in the target sea area, perform surface missions, and then take off from the sea to return, the risks of using large fixed-wing aircraft can be greatly reduced.

[0003] Most of the amphibious aircraft disclosed at home and abroad are rotorcraft that can take off and land vertically, such as the Chinese patent application "A Sea and Air Amphibious Robot" with publication number CN119239937A and the Chinese patent application "A Marine Exploration Amphibious UAV" with publication number CN118992148A. Although these aircraft have high floating stability on the water surface, the rotorcraft has low cruising efficiency in the air and short flight time, which makes it difficult to meet the mission requirements of vast waters. Traditional fixed-wing aircraft that can take off and land on water, such as the Chinese patent application "A Multi-modal Cross-domain Exploration Sea and Air Amphibious UAV and Detection Method" with publication number CN117262215A, have high requirements for the water surface environment due to their flat-lying take-off and landing and perching posture.

[0004] In contrast, the tail-seat fixed-wing amphibious multi-modal aircraft has both high cruising efficiency and the ability to take off and land vertically, which can meet the flight requirements of long flight time and long range, such as the Chinese patent application "Tail-seat sea-air cross-domain aircraft device based on quad-rotor drive" with publication number CN110775262A. Summary of the invention

[0005] Technical issues to be solved:

[0006] In the process of designing and verifying tail-seat fixed-wing water-air amphibious multi-mode aircraft, in order to improve the range and flight time, the aircraft is required to have a large lift-to-drag ratio in the cruise phase, so a large aspect ratio design is required, such as a large aspect ratio tailless layout design; for a tailless layout aircraft, when it is perched on the water surface in the form of a tail seat, since the buoyancy-providing float is located at the outer end of the wing of the tailless layout, the surface stability performance of the aircraft in the pitch direction is extremely low, and a slight wave will cause the aircraft to capsize in the pitch direction, making it difficult to meet the needs of surface operation tasks and difficult to take off again on the water surface. In the face of this problem, existing tail-seat tailless layout amphibious aircraft generally adopt the method of adding two more wing surfaces on the longitudinal symmetry plane of the aircraft and arranging floats at the outer end of the wing surface, but such a layout destroys the aerodynamic performance of the tailless layout aircraft in the cruise phase.

[0007] In view of the above problems, the present invention proposes a tail-seat type tailless layout amphibious aircraft with foldable wings and a design method. For the tail-seat type amphibious aircraft with tailless layout, by designing a foldable wing mechanism, the wings are unfolded to maintain a large aspect ratio layout when cruising in the air, and the wings are folded to form an envelope layout for the fuselage when perched on the water surface, thereby meeting the aerodynamic performance requirements of the tail-seat type amphibious aircraft with tailless layout in the air cruising mode and the requirements for the gravity center distance and floating stability in the water surface perching mode, and can also take off quickly under high sea conditions. It avoids the difficulty in designing the relative positions of the center of gravity, aerodynamic focus and center of gravity of traditional tail-seat fixed-wing aircraft in the two states of floating on the water surface and cruising in the air, and the problem that the traditional layout design is difficult to ensure the stability of the aircraft when floating on the water surface.

[0008] The technical solution of the present invention is:

[0009] A tailless amphibious aircraft with foldable wings, comprising a tailless fuselage, outer wings on both sides of the tailless fuselage, and floats fixed at the wingtips of the outer wings;

[0010] A revolute pair is formed between the outer wing and the same side end surface of the tailless fuselage, and the outer wing can be rotated relative to the tailless fuselage around a revolute axis under power drive and locked in place, and the revolute axis is parallel to the fuselage axis;

[0011] When the aircraft is in the air cruise mode, the outer wings on both sides of the tailless fuselage are flush with the tailless fuselage and locked, forming a tailless configuration that meets the air cruise mode;

[0012] When the aircraft is in the surface parking mode, the outer wings on both sides of the tailless fuselage rotate in the same clockwise direction around their respective rotation axes and lock into place, so that the center axis of the tailless fuselage is within the quadrilateral formed by the two buoys and the two rotation axes.

[0013] Furthermore, when the aircraft is in the water surface parking mode, the two buoy axes and the two rotation axis axes form a quadrilateral at the projection points of the fuselage cross section, the quadrilateral is a square, and the projection points of the fuselage axes at the fuselage cross section are at the centroid position of the square.

[0014] Furthermore, the buoy is a rotating body structure, and the buoy axis is parallel to the fuselage axis.

[0015] Furthermore, the outer end surface of one side of the tailless fuselage is connected to the inner end surface of the outer wing on the same side by a limit hinge, and the outer wing is driven to rotate around the hinge rotation axis by the servo; the outer end surface of the tailless fuselage and the inner end surface of the outer wing are also matched by telescopic pins and pin holes. When the tailless fuselage and the outer wing are in a flush state, the telescopic pin on the outer end surface of the tailless fuselage can be controllably inserted into the pin hole on the inner end surface of the outer wing to lock the outer wing, or controlledly pulled out from the pin hole to unlock the outer wing; when the outer wing rotates around the hinge rotation axis to the folding limit position, the rotation angle of the outer wing is maintained by the limit hinge.

[0016] The present invention also proposes a design method for the above-mentioned aircraft, comprising the following steps:

[0017] Step 1: Optimization design of aircraft cruise flight performance:

[0018] Step 1.1: Establish the basic configuration with a tailless fuselage and two outer wings, and select the wing span , Wing chord length distribution and the wing airfoil section shape as design parameters;

[0019] The wing span refers to the length from the central axis of the fuselage to the wing tip of the outer section wing; the wing chord length distribution refers to the length from the leading edge to the trailing edge of the wing at different positions in the wing span direction; the wing airfoil section shape refers to the wing airfoil section shape at a set position in the wing span direction;

[0020] Step 1.2: Taking the maximum lift-to-drag ratio of the aircraft as the design goal, based on the basic configuration, the design parameters selected in step 1.1 are optimized based on flight performance under the first constraint of the center of gravity position, lift constraint, pitch moment constraint and wing structure thickness constraint to obtain the intermediate design results;

[0021] The first constraint of the center of gravity position refers to that the ratio of the distance between the center of gravity and the aerodynamic focus of the aircraft to the average chord length of the wing is within a set range; the lift constraint refers to that the lift generated by the aircraft at the design cruising speed, design cruising altitude and design cruising angle of attack is equal to the gravity of the aircraft; the pitch moment constraint refers to that the pitch moment of the aircraft at the design cruising speed, design cruising altitude and design cruising angle of attack is less than a set value, ensuring that the aircraft can perform steady cruising flight; the wing structure thickness constraint refers to that the wing thickness can meet the space requirements for the internal structure layout of the wing;

[0022] Step 2: Optimization design of aircraft floating surface stability:

[0023] Step 2.1: Select the distance between the outer wing rotation axis and the fuselage center axis and the rotation angle of the outer wing As a design parameter;

[0024] Step 2.2: Based on the intermediate design results obtained in step 1, a folded configuration is established. With the optimal stability of the folded configuration in all directions as the design goal, the design parameters selected in step 2.1 are optimized under the second constraint of the center of gravity position, the moment of inertia constraint, and the wing structure constraint to obtain the final optimized design result;

[0025] The second constraint on the center of gravity position means that in the folded configuration, the center of gravity of the aircraft in the tail-seat posture is located below the center of gravity of the aircraft, and the distance between the center of gravity and the center of gravity is not less than a set value; the moment of inertia constraint means that in the folded configuration, the restoring moment of the aircraft in the tail-seat posture changes continuously with the change of the floating inclination angle, and there is no sudden change in the restoring moment; the wing structure constraint means that the position of the rotation axis of the outer section wing does not affect the operation of the internal structure of the wing;

[0026] Step 3: Determine whether the final optimization design result obtained in step 2 meets the requirements of isotropic stability under the folded configuration. If not, return to step 1 and re-establish the basic configuration.

[0027] Beneficial effects:

[0028] The tail-seat type tailless layout amphibious aircraft with foldable wings proposed in the present invention meets the aerodynamic performance requirements of the tailless layout tail-seat type amphibious aircraft in the air cruising mode and the gravity center distance and floating stability requirements in the water surface parking mode by designing a foldable wing structure, so that the aircraft can always maintain the tail-seat state when it is parked on the water surface, meeting the needs of performing surface operation tasks, and can also take off quickly under high sea conditions, thereby achieving the high flight performance of the aircraft in the air cruising state and the high stability in the water surface parking state.

[0029] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0031] Figure 1 It is a three-dimensional schematic diagram of an amphibious aircraft with a tailless layout in a wing-expanded state;

[0032] Figure 2 It is a front view of the tailless amphibious aircraft with its wings deployed;

[0033] Figure 3 It is a side view of the tailless amphibious aircraft with its wings extended;

[0034] Figure 4 It is a top view of the tailless amphibious aircraft with its wings extended;

[0035] Figure 5 It is a three-dimensional schematic diagram of an amphibious aircraft with a tailless layout in a wing-folded state;

[0036] Figure 6 It is a front view of the tailless amphibious aircraft with the wings folded;

[0037] Figure 7 It is a side view of the tailless amphibious aircraft with the wings folded;

[0038] Figure 8 It is a top view of the tailless amphibious aircraft with its wings folded;

[0039] Fig. 9 It is a block diagram of the optimized design of an amphibious aircraft with a tailless layout and foldable wings.

[0040] In the figure: 1. Fuselage; 2. Inner wing; 3. Outer wing; 4. Float. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0044] In this embodiment, a tail-seat type tailless layout amphibious aircraft with foldable wings is proposed, and a design method of the aircraft is given. The aircraft can take off vertically by taking off from land, taking off from a ship, etc., or it can be dropped from the air by a carrier aircraft and stay for a long time in a distant target mission water area; when receiving a mission instruction, it will land vertically in the target water area and perch on the water surface to perform surface missions, such as serving as a surface relay node and collecting underwater environmental information; after the surface mission is completed, the aircraft will take off vertically from the water surface again in a tail-seat manner and return. In this scenario, in the air cruising mode of flying to a distant target mission water area and staying for a long time, the aircraft needs to have a high lift-to-drag ratio and a large aspect ratio; and in the surface perching mode of performing surface missions, the aircraft needs to have all-directional stable stability performance under high sea conditions, maintain a tail-seat state, meet the needs of performing surface missions, and be able to take off stably on the water surface. To this end, the present embodiment proposes an amphibious aircraft with a tailless layout using foldable wings. In the air cruising mode, the wings are fully unfolded to form a tailless layout so that the aircraft has better cruising flight performance; while in the surface parking mode, the wings are folded to form an envelope layout for the fuselage, thereby achieving a higher gravity center distance and isotropic stability performance of the aircraft.

[0045] like Figure 1As shown, the aircraft includes a tailless fuselage, outer wings on both sides of the tailless fuselage, and pontoons fixed at the wingtips of the outer wings. The power system of the aircraft is not shown in the figure. The power system can use a forward-pull propeller at the head of the tailless fuselage, or a forward-pull propeller installed on the wing surfaces on both sides of the tailless fuselage. In addition, a control system and a mission load are arranged inside the fuselage, and the specific installation position is determined according to the design requirements. In addition, control rudders are arranged on the tailless fuselage and the trailing edge of the outer wings to achieve pitch, roll and yaw control of the aircraft. The pontoons are used to provide buoyancy for the aircraft in the water surface perching mode. In this embodiment, the pontoons are a rotating body structure, the pontoon axis is parallel to the fuselage axis, and the pontoon shape is designed with low resistance characteristics to reduce the aircraft resistance during air cruising.

[0046] A revolving pair is formed between the outer section wing and the end face on the same side of the tailless layout fuselage, and the outer section wing can rotate relative to the tailless layout fuselage around the rotation axis under power drive and lock in place, and the rotation axis is parallel to the fuselage axis. In this embodiment, the outer end face on one side of the tailless layout fuselage is connected to the inner end face of the outer section wing on the same side through a limit hinge, and the outer section wing is driven to rotate around the hinge rotation axis by the servo; the outer end face of the tailless layout fuselage and the inner end face of the outer section wing are also matched through a telescopic pin and a pin hole. When the tailless layout fuselage and the outer section wing are in a flush state, that is, a complete tailless layout is formed, the telescopic pin on the outer end face of the tailless layout fuselage can be controlled to be inserted into the pin hole on the inner end face of the outer section wing to lock the outer section wing, or controlled to be pulled out from the pin hole to unlock the outer section wing; when the outer section wing rotates around the hinge rotation axis to the folding limit position, the rotation angle of the outer section wing is maintained by the limit hinge.

[0047] like Figure 1~Figure 4 As shown, when the aircraft is in the air cruising mode, the outer wings on both sides of the tailless fuselage are flush with the tailless fuselage and locked, forming a tailless configuration that meets the air cruising mode.

[0048] like Figure 5~Figure 8 As shown, when the aircraft is in the water surface resting mode, the outer wings on both sides of the tailless fuselage rotate in place and are locked in the same clockwise direction around their respective rotation axes, so that the center axis of the tailless fuselage is in a quadrilateral formed by two pontoons and two rotation axes. Specifically, the projection point of the fuselage axis on the fuselage cross section is in a quadrilateral formed by the projection points of the two pontoon axes and the two rotation axis axes on the fuselage cross section. In order to better meet the requirements of isotropic stability, it is found through optimization design that when the quadrilateral is a square and the projection point of the fuselage axis is at the centroid position of the square, the isotropic stability of the aircraft on the water surface is optimal.

[0049] In this embodiment, a design method of the aircraft is also provided. Since the aircraft mainly has an air cruising mode and a water surface resting mode, the design is mainly divided into a cruising state flight performance optimization design process and a floating state water surface stability optimization design process. Specifically, the following steps are included:

[0050] Step 1: Optimization design of aircraft cruise flight performance:

[0051] Step 1.1: Establish the basic configuration with a tailless fuselage and two outer wings, and select the wing span , Wing chord length distribution and the wing airfoil shape as design parameters;

[0052] The wing span refers to the length from the central axis of the fuselage to the wingtip of the outer wing; the wing chord length distribution refers to the length from the leading edge to the trailing edge of the wing at different positions in the wing span direction; the wing airfoil profile shape refers to the wing airfoil profile shape at a set position in the wing span direction.

[0053] Step 1.2: Taking the maximum lift-to-drag ratio of the aircraft as the design goal, based on the basic configuration, the design parameters selected in step 1.1 are optimized based on flight performance under the first constraint of the center of gravity position, lift constraint, pitch moment constraint and wing structure thickness constraint to obtain the intermediate design results;

[0054] The first constraint on the center of gravity position refers to the ratio of the distance between the center of gravity and the aerodynamic focus of the aircraft to the average chord length of the wing is within a set range; the lift constraint refers to the lift generated by the aircraft at the design cruising speed, design cruising altitude and design cruise angle of attack is equal to the gravity of the aircraft; the pitch moment constraint refers to the pitch moment of the aircraft at the design cruising speed, design cruising altitude and design cruise angle of attack is less than a certain small value set, ensuring that the aircraft can achieve steady cruise flight; the wing structure thickness constraint refers to the wing thickness being able to meet the space requirements for the internal structure layout of the wing.

[0055] Step 2: Optimization design of aircraft floating surface stability:

[0056] Step 2.1: Select the distance between the outer wing rotation axis and the fuselage center axis and the rotation angle of the outer wing As a design parameter;

[0057] Step 2.2: Based on the intermediate design results obtained in step 1, a folded configuration is established. With the optimal stability of the folded configuration in all directions as the design goal, the design parameters selected in step 2.1 are optimized under the second constraint of the center of gravity position, the moment of inertia constraint, and the wing structure constraint to obtain the final optimized design result;

[0058] The second constraint on the center of gravity position means that in the folded configuration, the center of gravity of the aircraft when it is in the tail seat posture is located below the metacenter of the aircraft, and the distance between the metacenter and the center of gravity is not less than a set value; the moment of inertia constraint means that in the folded configuration, the restoring moment of the aircraft when it is in the tail seat posture changes continuously with the change of the floating inclination angle, and there is no sudden change in the restoring moment; the wing structure constraint means that the position of the rotation axis of the outer section wing does not affect the operation of the internal structure of the wing.

[0059] Step 3: Determine whether the final optimization design result obtained in step 2 meets the requirements of isotropic stability under the folded configuration. If not, return to step 1 and re-establish the basic configuration.

[0060] Through the above two-step optimization design process, it is ensured that the aircraft has both better air cruising performance and better stability performance in the floating state on the water surface. In this embodiment, through the optimization design of the floating state on the water surface stability, it is determined that in the folded state, when the projection point of the fuselage axis on the fuselage cross section is within the quadrilateral formed by the projection points of the two buoy axes and the two rotation axis axes on the fuselage cross section, and the quadrilateral is a square, and the projection point of the fuselage axis is at the centroid position of the square, the aircraft has the best stability in all directions on the water surface.

[0061] The tail-seat type tailless amphibious aircraft with foldable wings proposed in this embodiment meets the aerodynamic performance requirements of the tailless tail-seat type amphibious aircraft in the air cruising mode and the requirements of the gravity center distance and floating stability in the water surface parking mode by designing a foldable wing structure. When the aircraft is parked on the water surface, it can always maintain the tail-seat state to meet the needs of performing surface operation tasks, and can also take off quickly under high sea conditions, so that the aircraft can simultaneously have high flight performance in the air cruising state and high stability in the water surface parking state.

[0062] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A tail-seat type tailless amphibious aircraft with foldable wings, comprising a tailless fuselage, outer wings on both sides of the tailless fuselage, and pontoons fixed at the wingtips of the outer wings; characterized in that: A revolute pair is formed between the outer wing and the same side end surface of the tailless fuselage, and the outer wing can be rotated relative to the tailless fuselage around a revolute axis under power drive and locked in place, and the revolute axis is parallel to the fuselage axis; When the aircraft is in the air cruise mode, the outer wings on both sides of the tailless fuselage are flush with the tailless fuselage and locked, forming a tailless configuration that meets the air cruise mode; When the aircraft is in the surface parking mode, the outer wings on both sides of the tailless fuselage rotate in the same clockwise direction around their respective rotation axes and lock into place, so that the center axis of the tailless fuselage is within the quadrilateral formed by the two buoys and the two rotation axes.

2. The tail-seat type tailless layout amphibious aircraft with foldable wings according to claim 1, characterized in that: When the aircraft is in the water surface parking mode, the two buoy axes and the two rotation axis axes form a quadrilateral at the projection points of the fuselage cross section, the quadrilateral is a square, and the projection points of the fuselage axes at the fuselage cross section are at the centroid position of the square.

3. The tail-seat type tailless layout amphibious aircraft with foldable wings according to claim 1, characterized in that: The buoy is a rotating body structure, and the buoy axis is parallel to the fuselage axis.

4. The tail-seat type tailless layout amphibious aircraft with foldable wings according to claim 1, characterized in that: The outer end surface of one side of the tailless fuselage is connected to the inner end surface of the outer wing on the same side through a limit hinge, and the outer wing is driven to rotate around the hinge rotation axis by the servo; when the outer wing rotates around the hinge rotation axis to the folding limit position, the rotation angle of the outer wing is maintained by the limit hinge.

5. The tail-seat type tailless layout amphibious aircraft with foldable wings according to claim 4, characterized in that: The outer end surface of the tailless fuselage and the inner end surface of the outer wing are also matched through telescopic pins and pin holes. When the tailless fuselage and the outer wing are in a flush state, the telescopic pin on the outer end surface of the tailless fuselage can be controlled to be inserted into the pin hole on the inner end surface of the outer wing to lock the outer wing, or controlled to be pulled out of the pin hole to unlock the outer wing.

6. The design method of a tail-seat tailless amphibious aircraft with foldable wings according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Optimization design of aircraft cruise flight performance: Step 1.1: Establish the basic configuration with a tailless fuselage and two outer wings, and select the wing span , Wing chord length distribution and the wing airfoil section shape as design parameters; Step 1.2: Taking the maximum lift-to-drag ratio of the aircraft as the design goal, based on the basic configuration, the design parameters selected in step 1.1 are optimized based on flight performance under the first constraint of the center of gravity position, lift constraint, pitch moment constraint and wing structure thickness constraint to obtain the intermediate design results; The first constraint of the center of gravity position refers to that the ratio of the distance between the center of gravity and the aerodynamic focus of the aircraft to the average chord length of the wing is within a set range; The lift constraint means that the lift generated by the aircraft at the design cruising speed, design cruising altitude and design cruising angle of attack is equal to the gravity of the aircraft; the pitch moment constraint means that the pitch moment of the aircraft at the design cruising speed, design cruising altitude and design cruising angle of attack is less than the set value, ensuring that the aircraft can perform steady cruising flight; the wing structure thickness constraint means that the wing thickness can meet the space requirements for the internal structure layout of the wing; Step 2: Optimization design of aircraft floating surface stability: Step 2.1: Select the distance between the outer wing rotation axis and the fuselage center axis and the rotation angle of the outer wing As a design parameter; Step 2.2: Based on the intermediate design results obtained in step 1, a folded configuration is established. With the optimal stability of the folded configuration in all directions as the design goal, the design parameters selected in step 2.1 are optimized under the second constraint of the center of gravity position, the moment of inertia constraint, and the wing structure constraint to obtain the final optimized design result; The second constraint on the center of gravity position means that in the folded configuration, the center of gravity of the aircraft in the tail-seat posture is located below the center of gravity of the aircraft, and the distance between the center of gravity and the center of gravity is not less than a set value; the moment of inertia constraint means that in the folded configuration, the restoring moment of the aircraft in the tail-seat posture changes continuously with the change of the floating inclination angle, and there is no sudden change in the restoring moment; the wing structure constraint means that the position of the rotation axis of the outer section wing does not affect the operation of the internal structure of the wing; Step 3: Determine whether the final optimization design result obtained in step 2 meets the requirements of isotropic stability under the folded configuration. If not, return to step 1 and re-establish the basic configuration.

7. The design method according to claim 6, characterized in that: The wing span refers to the length from the central axis of the fuselage to the wingtip of the outer wing; the wing chord length distribution refers to the length from the leading edge to the trailing edge of the wing at different positions in the wing span direction; the wing airfoil profile shape refers to the wing airfoil profile shape at a set position in the wing span direction.

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