A method, system and device for optimizing the control of retraction and extension of landing gear of a flying wing aircraft

Abstract

The present application discloses a method, system and device for optimizing the control of the retraction and extension of the landing gear of a flying wing aircraft. The present application relates to the field of control technology of flying wing aircraft. The method includes adopting a numerical simulation calculation method to obtain aerodynamic data under the influence of the landing gear cover of the flying wing aircraft; based on the aerodynamic data, analyzing the degree of deterioration of the static instability of the heading in each state of the retraction and extension process of the landing gear cover of the flying wing aircraft; analyzing the drag rudder effect in each state of the retraction and extension process of the landing gear cover of the flying wing aircraft under the condition of the sideslip angle; according to the analysis results, obtaining the retraction and extension control strategy of the landing gear cover and the restriction requirements of the sideslip angle, so as to optimize the retraction and extension of the landing gear. The present application adopts numerical simulation technology to analyze the aerodynamic characteristics, control stability characteristics and flight control laws of the aircraft in the lateral direction under the influence of the landing gear cover, and designs an optimized landing gear retraction and extension control strategy based on this, providing technical support for the development of flying wing aircraft.

Description

Technical Field

[0001] The present application relates to the technical field of flying wing aircraft control, and in particular to a method, system and device for optimizing the control of retraction and extension of landing gear of a flying wing aircraft. Background Art

[0002] The flying wing aircraft has eliminated the vertical tail and rudder, which greatly reduces the radar cross-section, reduces the weight of the entire aircraft, and improves the aerodynamic characteristics. However, the change in configuration, the shortened fuselage, and the tailless layout cause the aerodynamics, motion, and control to exhibit nonlinear characteristics and be mutually coupled, bringing about new problems such as static instability in heading and insufficient maneuverability. Therefore, it is necessary to introduce active control technology to ensure that the aircraft has excellent flight qualities.

[0003] At present, the research on flying wing aircraft at home and abroad mainly focuses on the analysis of the aircraft's handling characteristics, control and stability augmentation design, and the distribution of rudder control, but the analysis of the impact of the landing gear on the heading of statically unstable aircraft is rarely involved. For aircraft that take off and land by taxi, retracting and extending the landing gear is an indispensable process. At this time, the aircraft is flying at a low altitude, at a low speed, with weak rudder effect, and with strong external wind interference, which is usually a link where accidents frequently occur. Therefore, it is very necessary to study the changes in the characteristics of the aircraft's lateral heading when the landing gear and its hatch are retracted and extended. Summary of the invention

[0004] In order to fill the gap in the research on the characteristic changes of the landing gear of a flying wing layout aircraft in the lateral direction and ensure flight quality and safety, the present application proposes a flying wing layout aircraft landing gear retraction and extension optimization control method, system and equipment. The present application adopts numerical simulation technology to analyze the aerodynamic characteristics, stability characteristics and flight control laws of the aircraft in the lateral direction under the influence of the landing gear cover, and based on this, designs an optimized landing gear retraction and extension control strategy to ensure the flight quality and safety of the aircraft, providing technical support for the development of flying wing layout aircraft.

[0005] This application is implemented through the following technical solutions:

[0006] A method for optimizing the retraction and extension control of a flying wing aircraft landing gear, the method comprising:

[0007] The numerical simulation method is used to obtain the aerodynamic data under the influence of the landing gear cover of the flying wing aircraft.

[0008] Based on the aerodynamic data, analyzing the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process of the flying wing aircraft;

[0009] Based on the aerodynamic data, the drag rudder effect of the flying wing aircraft under various states of the landing gear cover retraction and extension process is analyzed under the condition of sideslip angle;

[0010] According to the deterioration degree of heading static instability caused by various states of the landing gear cover retraction and extension process and the analysis results of the drag rudder efficiency, the landing gear cover retraction and extension control strategy and the side slip angle limitation requirements are obtained to perform the landing gear retraction and extension optimization control.

[0011] In some embodiments, the numerical simulation calculation method is used to obtain aerodynamic data under the influence of the landing gear cover of the flying wing aircraft, specifically including:

[0012] The retraction and extension process of the landing gear cover is divided into 6 states:

[0013] State0 is the state without landing gear cover interference;

[0014] State 1 is the state where the front hatch cover and the main hatch cover are fully opened;

[0015] State2 is the state where all front hatch covers are open and all main hatch covers are closed;

[0016] State3 is the state where the front hatch covers are all closed and the main hatch covers are all opened;

[0017] State 4 is the state where all front hatch covers are opened, the left main hatch cover A and the right main hatch cover A are closed, and the left main hatch cover B and the right main hatch cover B are opened;

[0018] State 5 is the state where the front hatch cover and the left main hatch cover are all closed, and the right main hatch cover is all opened;

[0019] The aerodynamic data of the flying wing aircraft landing gear cover retraction and extension process under the influence of various states are obtained by simulation calculation using a three-dimensional non-structural solver based on the finite volume method.

[0020] In some embodiments, the analyzing, based on the aerodynamic data, the degree of deterioration of the static directional instability caused by each state of the landing gear cover retraction and extension process of the flying wing aircraft specifically includes:

[0021] According to the aerodynamic data, a heading static stability derivative curve in the entire data packet curve in each state of the landing gear cover retraction and extension process of the flying wing layout aircraft is obtained;

[0022] According to the degree of negative deviation of the heading static stability derivative curve in the entire data packet line under each state, the deterioration degree of the heading static instability under each state is obtained and ranked.

[0023] In some embodiments, the analysis of the drag rudder effect of the flying wing aircraft landing gear cover retraction and extension process under the condition of the sideslip angle based on the aerodynamic data specifically includes:

[0024] According to the aerodynamic data, the drag rudder effect of the flying wing aircraft under different sideslip angle conditions in each state of the landing gear cover retraction and extension process is obtained;

[0025] A limiting threshold of the sideslip angle is determined according to the resistance rudder effect.

[0026] In some embodiments, the control strategy for retracting and extending the landing gear cover and the side slip angle limitation requirements are obtained according to the degree of deterioration of the heading static instability caused by each state of the retracting and extending process of the landing gear cover and the analysis results of the drag rudder effect, specifically including:

[0027] Determining the combination relationship of various states of the landing gear retraction and extension process of the flying wing layout aircraft according to the optimization conditions;

[0028] Wherein, the optimization condition is:

[0029] The value of the heading static stability derivative of the flying wing layout aircraft body is a positive value;

[0030] Also, under the sideslip angle condition, the drag rudder deflection can correct the adverse yaw moment.

[0031] In some embodiments, in the sideslip angle state, the deflection of the drag rudder can correct the adverse yaw moment, specifically including:

[0032] Eliminate side slip angle;

[0033] Alternatively, the sideslip angle is limited, that is, the absolute value of the sideslip angle is smaller than a limiting threshold;

[0034] Alternatively, when the absolute value of the sideslip angle is greater than a limiting threshold, the landing gear cover of the flying wing aircraft is prevented from being in a state where the drag rudder cannot generate a desired yaw moment.

[0035] In a second aspect, the present application proposes a flying wing aircraft landing gear retraction and extension optimization control system, the system comprising:

[0036] An aerodynamic analysis module, wherein the aerodynamic analysis module uses a numerical simulation calculation method to obtain aerodynamic data under the influence of a landing gear cover of a flying wing aircraft;

[0037] a static instability analysis module, wherein the static instability analysis module analyzes the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process of the flying wing aircraft based on the aerodynamic data;

[0038] A rudder effect analysis module, wherein the rudder effect analysis module analyzes the drag rudder effect of the flying wing aircraft in various states of the landing gear cover retraction and extension process under the condition of the sideslip angle based on the aerodynamic data;

[0039] And, an optimization module, which obtains the landing gear cover retraction and extension control strategy and the sideslip angle limitation requirements according to the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process and the resistance rudder effect analysis results, so as to perform the landing gear retraction and extension optimization control.

[0040] In some embodiments, the aerodynamic analysis module uses a three-dimensional non-structural solver based on a finite volume method to simulate and calculate the aerodynamic data of the landing gear cover of the flying wing aircraft under the influence of various states;

[0041] The retracting and extending process of the landing gear cover of the flying wing aircraft is divided into 6 states:

[0042] State0 is the state without landing gear cover interference;

[0043] State 1 is the state where the front hatch cover and the main hatch cover are fully opened;

[0044] State2 is the state where all front hatch covers are open and all main hatch covers are closed;

[0045] State3 is the state where the front hatch covers are all closed and the main hatch covers are all opened;

[0046] State 4 is the state where all front hatch covers are opened, the left main hatch cover A and the right main hatch cover A are closed, and the left main hatch cover B and the right main hatch cover B are opened;

[0047] State 5 is a state in which the front hatch cover and the left main hatch cover are all closed, and the right main hatch cover is all opened.

[0048] In some embodiments, the static instability analysis module is specifically configured to perform the following process:

[0049] According to the aerodynamic data, a heading static stability derivative curve in the entire data packet curve in each state of the landing gear cover retraction and extension process of the flying wing layout aircraft is obtained;

[0050] According to the degree of negative deviation of the heading static stability derivative curve in the entire data packet line under each state, the deterioration degree of the heading static instability under each state is obtained and ranked.

[0051] In a third aspect, the present application proposes a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0052] The present application proposes a method, system and equipment for optimizing the control of retraction and extension of the landing gear of a flying wing aircraft. The numerical simulation technology is used to analyze the aerodynamic characteristics, handling stability characteristics and flight control laws of the flying wing aircraft in the lateral direction under the influence of the landing gear cover, and a reasonably optimized landing gear cover retraction and extension control strategy is proposed, which improves the flight stability and safety of the aircraft and provides technical support for the research of flying wing aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The drawings described herein are used to provide a further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0054] Figure 1 A schematic diagram of the landing gear canopy layout for a flying wing aircraft;

[0055] Figure 2 is the heading static stability derivative of the flying wing aircraft body obtained based on wind tunnel tests;

[0056] Figure 3 is the lateral static stability derivative of the flying wing aircraft body obtained based on wind tunnel tests;

[0057] Figure 4 is the lateral control deviation parameter of the flying wing aircraft body obtained based on wind tunnel tests;

[0058] Figure 5 This is a flow chart of the optimization control method of an embodiment of the present application;

[0059] Figure 6 The lateral static stability derivatives of the flying wing aircraft landing gear cover under various conditions during the retraction and extension process;

[0060] Figure 7 The heading static stability derivatives of the flying wing aircraft under various conditions during the retraction and extension of the landing gear cover;

[0061] Figure 8 The drag rudder effect under the condition of 5° sideslip angle;

[0062] Fig. 9 The drag rudder effect under the condition of 8° sideslip angle;

[0063] Fig.10 This is a principle block diagram of the optimization control system of an embodiment of the present application;

[0064] Fig.11 This is the simulation result diagram of the sideslip angle response of a flying wing aircraft when it encounters a positive crosswind;

[0065] Fig.12 This is the simulation result diagram of the rudder response of a flying wing aircraft when it encounters a positive crosswind;

[0066] Fig.13 The side slip angle and rudder response results of the flying wing aircraft when the landing gear is retracted during the flight test;

[0067] Fig.14 The side slip angle and rudder response results of the flying wing aircraft with the landing gear lowered during the flight test;

[0068] Reference numerals and corresponding component names:

[0069] 1-Hatch cover A from the front, 2-Hatch cover B from the front, 3-Hatch cover A from the left, 4-Hatch cover B from the left, 5-Hatch cover A from the right, 6-Hatch cover B from the right. DETAILED DESCRIPTION

[0070] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0071] Embodiment 1: The flying wing layout aircraft (hereinafter referred to as aircraft) described in this embodiment has the characteristics of a flat wing-body fusion body, a front three-point landing gear, and a front wheel for steering. It has two engines and a total of 4 groups of aerodynamic control surfaces, which are mainly divided into three types: drag-type rudders (2 groups, front and rear drag plates); elevators (1 group); ailerons (1 group). In comparison with the control habits of the rudders of conventional aircraft, it is stipulated that the aileron differential deflection is positive when the left trailing edge is upward and the right trailing edge is downward, and the elevator trailing edge is positive when it is downward, and it is positive when the left spoiler is opened, generating a negative torque. The influence of retracting the landing gear on the aircraft's handling characteristics is mainly caused by the landing gear hatch. In order to reduce its deteriorating effect on the lateral and heading stability, the hatch is designed in pieces, such as Figure 1 As shown, the front landing gear cover and the left and right main landing gear covers are divided into two parts and can be opened and closed independently.

[0072] The commonly used criterion for the lateral stability of an aircraft is shown in the following formula (1):

[0073] (1)

[0074] in, is the heading static stability derivative, is the lateral static stability derivative, is the lateral control deviation parameter. The static stability derivative directly reflects the heading stability and lateral stability, while the lateral control deviation parameter is used to ensure the stability and maneuverability during flight, and can also be used as the most important criterion for predicting the deviation characteristics and spin sensitivity of the aircraft. When the condition of formula (1) is met, the aircraft is in a statically stable state. For conventional layout aircraft, it strictly satisfies formula (1).

[0075] For flying wing aircraft, wind tunnel tests can be used to obtain Figure 2-Figure 4 The directional static stability derivative, lateral static stability derivative and lateral control deviation parameter of the flying wing aircraft are shown. Figure 2-Figure 4 It can be seen that the aircraft is statically stable laterally, but its heading is not statically stable within the entire data packet line, that is, Figure 2 As shown in , in the entire data packet line, the heading static stability derivative is less than 0, which does not meet the requirements of formula (1) and the heading is statically unstable. In addition, Figure 4 It can be seen that when the angle of attack (alpha) is less than 6.8°, the lateral control deviation parameter is less than 0, and the heading is easy to diverge when the surface is rolling controlled. It can be seen that the lateral and heading stability characteristics of the flying wing layout aircraft are poor, so it is very necessary to evaluate the interference of the landing gear canopy on the aircraft to ensure the flight stability and safety of the flying wing layout aircraft.

[0076] Based on this, this embodiment proposes a method for optimizing the control of retraction and extension of the landing gear of a flying wing layout aircraft. The method proposed in this embodiment uses numerical simulation technology to analyze the aerodynamic characteristics, stability characteristics and flight control laws in the lateral direction of the flying wing layout aircraft under the influence of the retraction and extension of the landing gear cover, and proposes a reasonably optimized retraction and extension control strategy for the landing gear cover, thereby improving the flight quality and safety of the aircraft and providing technical support for the development of flying wing layout aircraft.

[0077] like Figure 5 As shown, the optimization control method proposed in this embodiment specifically includes the following steps:

[0078] Step 100, using a numerical simulation calculation method to obtain aerodynamic data under the influence of a landing gear cover of a flying wing aircraft.

[0079] Specifically, step 100 can use the three-dimensional non-structural solver PMB3D based on the finite volume method independently developed by the applicant to simulate and calculate the aerodynamic data under the influence of the landing gear cover of the flying wing aircraft, wherein the main control equation is the unsteady compressible RANS (Reynolds-Averaged Navier-Stokes) equation, the turbulence model selected is the SA model, the Mach number Ma=0.2 at the calculation point, and the altitude Alt=2km. The process of using PMB3D to simulate and calculate aerodynamic data mainly includes: (1) preprocessing and mesh generation. Before starting the solution, the geometric model needs to be preprocessed and a mesh system suitable for the solver needs to be generated; (2) setting the solution parameters. According to the simulation requirements, the boundary conditions, initial conditions and solution parameters are set. These parameters will affect the accuracy of the solution process and results; (3) parallel computing. Using the parallel computing capabilities of PMB3D, large-scale numerical simulations of aerodynamic problems are performed. PMB3D supports multi-block structured grids and can effectively handle complex geometric shapes and flow conditions; (4) solver execution. Running the PMB3D solver will calculate various aerodynamic characteristics of the flow field based on the set parameters and mesh system.

[0080] The retraction and extension process of the landing gear hatch cover is divided into 6 states: State 1 is the state where the front hatch cover and the main hatch cover are all open; State 2 is the state where the front hatch cover is all open and the main hatch cover is all closed; State 3 is the state where the front hatch cover is all closed and the main hatch cover is all open; State 4 is the state where the front hatch cover is all open, the left main hatch cover A and the right main hatch cover A are closed, and the left main hatch cover B and the right main hatch cover B are open; State 5 is the state where the front hatch cover and the left main hatch cover are all closed, and the right main hatch cover is all open. In addition, State 0 is the state where there is no interference from the landing gear hatch cover.

[0081] The above-mentioned solver PMB3D is used to simulate and calculate the aerodynamic data under the influence of various states of the landing gear cover retraction and extension process, including but not limited to the yaw moment coefficient and rolling moment coefficient under different angles of attack and sideslip angles; the yaw moment coefficient under different rudder deflection angles, etc., so as to obtain the aircraft lateral static stability derivative and heading static stability derivative under various states of the landing gear cover retraction and extension process, as well as the yaw moment under various states under the sideslip angle condition.

[0082] Step 200, based on the above aerodynamic data, analyzing the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process of the flying wing aircraft.

[0083] According to the obtained aerodynamic data, step 200 can obtain the lateral static stability derivative curve and the heading static stability derivative curve in the entire data packet line in each state during the retraction and extension process of the landing gear cover of the flying wing aircraft, such as Figure 6 and Figure 7As shown. Among them, the lateral static stability derivative is the derivative of the rolling moment coefficient relative to the sideslip angle; the heading static stability derivative is the derivative of the yaw moment coefficient relative to the sideslip angle, and alpha is the angle of attack.

[0084] Depend on Figure 7 It can be analyzed that the lowering of the landing gear cover will further increase the heading static instability, that is, further deviation to the negative direction will worsen the heading static instability. Therefore, the degree of deterioration of the heading static instability derivative curve to the negative direction can be analyzed to obtain the degree of deterioration of the heading static instability in each state, as shown in Figure 7 It can be obtained that the deterioration degree of each state is ranked from large to small: State1, State2, State4, State3, State5, that is, the state with the largest deterioration degree is State1 (i.e., deviating to the negative direction and farthest from State0), and the state with the smallest deterioration degree is State5 (i.e., deviating to the negative direction and closest to State0). In addition, by Figure 6 It can be analyzed that the lateral static stability will be enhanced when the landing gear cover is lowered, but the impact is small compared to the heading.

[0085] Need to explain, Figure 6 and Figure 7 This is only an exemplary description, which only represents the aerodynamic analysis results of a certain flying wing aircraft, and does not limit the order of the heading static instability deterioration process. For a flying wing aircraft, it is sufficient to determine the order of the heading static instability deterioration degree in each state of the landing gear cover retraction and extension process according to the degree of negative deviation of the heading static stability derivative curve obtained in the above analysis method, instead of necessarily having the above order result.

[0086] Step 300, based on the above aerodynamic data, analyzing the drag rudder effect in various states of the landing gear cover retraction and extension process of the flying wing aircraft under the side slip angle condition.

[0087] In step 300, based on the obtained aerodynamic data, the drag rudder effect of the flying wing aircraft landing gear cover retraction and extension process under different sideslip angles (Beta) is analyzed, that is, whether the -25° rudder can generate the expected yaw moment. For example, Figure 8 The yaw moment generated by the -25° rudder at a 5° sideslip angle is shown. Fig. 9 The figure shows the yaw moment generated by the -25° rudder under the condition of 8° sideslip angle. The yaw moment generated by the -25° rudder, i.e. the drag rudder effect CnSB, is the derivative of the yaw moment coefficient relative to the rudder deflection angle. Figure 8 and Fig. 9The analysis shows that within the trim angle of attack range, if there is a 5° sideslip angle, the rudder deflected by 25° in State1 and State2 cannot produce the expected yaw moment. When the sideslip angle further increases to 8°, the situation worsens further, which will bring great flight hazards to aircraft with static heading instability. Therefore, it is necessary to optimize the landing gear retraction and extension control strategy to reduce the aerodynamic characteristics disturbance during the aircraft configuration change process, and the sideslip angle must be strictly limited to ensure flight safety.

[0088] It should be noted that Figure 8 and Fig. 9 This is only an exemplary description, which only represents the aerodynamic analysis result of a flying wing layout aircraft, and does not limit the specific size of the sideslip angle. It is only necessary to determine the restriction requirement of the sideslip angle (eliminate or determine the restriction threshold, etc.) according to the above analysis method, that is, by analyzing the yaw moment (i.e., the drag rudder effect) generated by the -25° rudder under different sideslip angles.

[0089] In addition, it is worth noting that the execution process of step 200 and step 300 does not need to be performed in sequence. Step 200 can be executed first and then step 300, or step 300 can be executed first and then step 200, or step 200 and step 300 can be executed simultaneously.

[0090] Step 400, according to the deterioration degree of the heading static instability caused by each state of the landing gear cover retraction and extension process and the drag rudder effect analysis result, the landing gear cover retraction and extension control strategy and the side slip angle limitation requirement are obtained to perform the landing gear retraction and extension optimization control.

[0091] This step 400 optimizes the order of retracting and extending the landing gear cover according to the analysis results of step 200 and step 300, thereby obtaining the retracting and extending control strategy of the landing gear cover and the side slip angle limitation requirement. Among them, the retracting and extending control strategy of the landing gear cover and the side slip angle limitation requirement need to meet the following two optimization conditions:

[0092] (1) The value of the heading static stability derivative of the flying wing aircraft body is positive, which means that the heading static stability requirement is met;

[0093] (2) Under the state of sideslip angle, the deflection of the drag rudder can correct the adverse yaw moment. A flying wing aircraft is a statically unstable aircraft. The sideslip angle will cause an adverse yaw moment on the nose, further causing the aircraft to lose control. CnSB is the drag rudder effect. Therefore, it is necessary to ensure that the rudder can still correct the adverse yaw moment under the state of sideslip angle.

[0094] According to the above two optimization conditions and the analysis results of step 200 and step 300, the order of retracting and extending the landing gear cover (i.e., the combination relationship of various states in the retracting and extending process of the landing gear cover) is optimized, and the sideslip angle is eliminated in time, the sideslip angle is limited (the absolute value of the sideslip angle is made less than a threshold value), or when the absolute value of the sideslip angle is greater than a threshold value, it is avoided that the aircraft landing gear cover is in a state where the drag rudder cannot generate the desired yaw moment.

[0095] according to Figure 6-Figure 9 For example, we can get the canopy control strategy when the landing gear is retracted as:

[0096] (1) The left main lift hatch cover B and the right main lift hatch cover B are opened;

[0097] (2) Open both front hatch covers A and B and retract the front landing gear.

[0098] (3) Both front hatch covers A and B are closed;

[0099] (4) Open the left main lift hatch cover A and the right main lift hatch cover A, and retract the main landing gear;

[0100] (5) The left main hatch covers A, B and the right main hatch covers A, B are closed.

[0101] The hatch cover control strategy when the landing gear is lowered is:

[0102] (1) The left main lift hatch cover B and the right main lift hatch cover B are opened;

[0103] (2) Open the left main lift hatch cover A and the right main lift hatch cover A and lower the main landing gear;

[0104] (3) The left main lift hatch cover A and the right main lift hatch cover A are closed;

[0105] (4) Open both front hatch covers A and B and lower the front landing gear;

[0106] (5) Close all front hatch covers A.

[0107] At the same time, the sideslip angle and landing gear cover State 1 and State 2 will weaken the rudder effect, so it is necessary to eliminate the sideslip angle in time and avoid the aircraft being in State 1 and State 2 when the absolute value of the sideslip angle is greater than 5°.

[0108] This embodiment also proposes a flying wing layout aircraft landing gear retraction and extension optimization control system. Fig.10 As shown, the system includes:

[0109] An aerodynamic analysis module, which uses numerical simulation calculation methods to obtain aerodynamic data under the influence of the landing gear cover of a flying wing aircraft;

[0110] The static instability analysis module analyzes the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process of the flying wing layout aircraft based on the above aerodynamic data.

[0111] The rudder effect analysis module analyzes the drag rudder effect of the flying wing aircraft under various states of the landing gear cover retraction and extension process under the conditions of sideslip angle based on the above aerodynamic data.

[0112] And, an optimization module, which obtains the landing gear cover retraction and extension control strategy and the sideslip angle limitation requirements according to the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process and the results of the resistance rudder rudder efficiency analysis, so as to perform the landing gear retraction and extension optimization control.

[0113] It should be noted that the specific implementation process of each functional module in the system is as described in the above method, and will not be elaborated here.

[0114] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0115] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0117] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0118] Example 2: In order to verify the effectiveness of the optimization control method proposed in Example 1 above, a simulation system was established using the landing gear retraction and extension control strategy of a certain example (flying wing layout aircraft) obtained by the optimization control method proposed in Example 1 above to describe the scenario in which the aircraft suddenly encounters a positive crosswind when retracting or extending the landing gear.

[0119] In the simulation system, the mathematical models of the airflow system and the body axis system sensors are obtained by identifying the previous flight data. The atmospheric model consists of three modules: background wind, turbulence, and wind shear. Among them, the background wind module mainly simulates the peaks in the three directions of northeast, east and ground; the turbulence module is described in the form of power spectrum, and the von Karman turbulence model can be used specifically; the wind shear module mainly simulates the spatiotemporal changes of wind, mainly considering its influence on angular velocity.

[0120] The flight speed is set to 45m / s. At the 20th second, a positive crosswind of 5m / s is encountered. The simulation results are as follows: Fig.11 and Fig.12 shown.

[0121] Among them, Fig.11 and Fig.12 It can be seen that after adding the influence of the landing gear cover, the amplitude of the oscillation of the sideslip angle (Beta) becomes larger and the time becomes longer; the maximum value of the rudder output (DRCMD) also increases from 32° to 41°. Under such harsh test conditions, the entire process is still under control and no divergence occurs, indicating that the landing gear retraction and extension optimization control technology proposed in the above embodiment 1 of the present application is feasible.

[0122] Example 3: This example adopts the optimization control method proposed in Example 1 above to obtain the landing gear retraction and extension control strategy of a certain example (flying wing layout aircraft), conducts a simulated flight test of the aircraft, and completes the powered autonomous takeoff / landing test project. During the flight test, there is a wind of more than 6m / s on the runway, and there is no constant wind direction. Among them, the flight speed when the landing gear is retracted is 45m / s, and the flight speed when the landing gear is extended is 50m / s. The sideslip angle (Beta) and the rudder command value (DRCMD) are as follows: Fig.13 and Fig.14 shown.

[0123] Depend on Fig.13 and Fig.14The flight data shows that the retraction and extension of the landing gear will produce disturbances in the lateral heading, but the flight control system has a good disturbance suppression effect overall. Among them, the fluctuation amplitude of the sideslip angle exceeds 5° when the landing gear is retracted, and the rudder output exceeds 15°, while the impact of the landing gear extension stage is relatively small. This is because the flight speed is low when the landing gear is retracted, the aircraft's anti-disturbance ability is weak, and the aircraft's flight altitude at this time is also low, and the terrain wind around the airport is strong.

[0124] Based on this, the optimization control method proposed in the embodiment of the present application can optimize the landing gear retraction and extension control strategy, so that the aircraft can maintain flight controllability and safety within the flight speed envelope, has strong robustness, and provides technical support for the verification of flying wing layout aircraft.

[0125] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for optimizing the retraction and extension of a flying wing aircraft landing gear, characterized in that: The method comprises: The numerical simulation method is used to obtain the aerodynamic data under the influence of the landing gear cover of the flying wing aircraft. Based on the aerodynamic data, analyzing the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process of the flying wing aircraft; Based on the aerodynamic data, the drag rudder effect of the flying wing aircraft under various states of the landing gear cover retraction and extension process is analyzed under the condition of sideslip angle; According to the deterioration degree of the heading static instability caused by each state of the landing gear cover during the retraction and extension process and the analysis results of the drag rudder effect, the landing gear cover retraction and extension control strategy and the side slip angle restriction requirements are obtained to perform the landing gear retraction and extension optimization control; the aerodynamic data under the influence of the landing gear cover of the flying wing layout aircraft is obtained by using the numerical simulation calculation method, which specifically includes: The retraction and extension process of the landing gear cover is divided into 6 states: State0 is the state without landing gear cover interference; State 1 is the state where the front hatch cover and the main hatch cover are fully opened; State2 is the state where all front hatch covers are open and all main hatch covers are closed; State3 is the state where the front hatch covers are all closed and the main hatch covers are all opened; State 4 is the state where all front hatch covers are opened, the left main hatch cover A and the right main hatch cover A are closed, and the left main hatch cover B and the right main hatch cover B are opened; State 5 is the state where the front hatch cover and the left main hatch cover are all closed, and the right main hatch cover is all opened; The aerodynamic data of the flying wing aircraft landing gear cover retraction and extension process under the influence of various states are obtained by simulation calculation using a three-dimensional non-structural solver based on the finite volume method.

2. The method for optimizing the retraction and extension of a flying wing aircraft landing gear according to claim 1, characterized in that: The analyzing, based on the aerodynamic data, the degree of deterioration of the heading static instability caused by each state of the landing gear cover retraction and extension process of the flying wing aircraft specifically includes: According to the aerodynamic data, a heading static stability derivative curve in the entire data packet curve in each state of the landing gear cover retraction and extension process of the flying wing layout aircraft is obtained; According to the degree of negative deviation of the heading static stability derivative curve in the entire data packet line under each state, the degree of deterioration of the heading static instability under each state is obtained and ranked.

3. The method for optimizing the retraction and extension of a flying wing aircraft landing gear according to claim 1, characterized in that: The analysis of the drag rudder effect of the flying wing aircraft landing gear cover retraction and extension process under the condition of the sideslip angle based on the aerodynamic data specifically includes: According to the aerodynamic data, the drag rudder effect of the flying wing aircraft under different sideslip angle conditions in each state of the landing gear cover retraction and extension process is obtained; A limiting threshold of the sideslip angle is determined according to the resistance rudder effect.

4. The method for optimizing the retraction and extension of a flying wing aircraft landing gear according to any one of claims 1 to 3, characterized in that: The above-mentioned method obtains the control strategy for retracting and extending the landing gear cover and the restriction requirements for the sideslip angle according to the deterioration degree of the heading static instability caused by each state of the retracting and extending process of the landing gear cover and the analysis results of the drag rudder effect, which specifically includes: Determining the combination relationship of various states of the landing gear retraction and extension process of the flying wing layout aircraft according to the optimization conditions; Wherein, the optimization condition is: The value of the heading static stability derivative of the flying wing layout aircraft body is a positive value; Also, under the sideslip angle condition, the drag rudder deflection can correct the adverse yaw moment.

5. The method for optimizing the retraction and extension of a flying wing aircraft landing gear according to claim 4, characterized in that: Under the sideslip angle state, the deflection of the drag rudder can correct the adverse yaw moment, specifically including: Eliminate side slip angle; Alternatively, the sideslip angle is limited, that is, the absolute value of the sideslip angle is smaller than a limiting threshold; Alternatively, when the absolute value of the sideslip angle is greater than a limiting threshold, the landing gear cover of the flying wing aircraft is prevented from being in a state where the drag rudder cannot generate a desired yaw moment.

6. A flying wing aircraft landing gear retraction and extension optimization control system, characterized in that: The system comprises: An aerodynamic analysis module, wherein the aerodynamic analysis module uses a numerical simulation calculation method to obtain aerodynamic data under the influence of a landing gear cover of a flying wing layout aircraft; a static instability analysis module, wherein the static instability analysis module analyzes the degree of deterioration of the heading static instability caused by various states of the landing gear cover retraction and extension process of the flying wing aircraft based on the aerodynamic data; A rudder effect analysis module, wherein the rudder effect analysis module analyzes the drag rudder effect of the flying wing aircraft in various states of the landing gear cover retraction and extension process under the condition of a sideslip angle based on the aerodynamic data; and, an optimization module, wherein the optimization module obtains the landing gear cover retraction and extension control strategy and the side slip angle restriction requirements according to the deterioration degree of the heading static instability caused by each state of the landing gear cover retraction and extension process and the drag rudder effect analysis result, so as to perform the landing gear retraction and extension optimization control; the aerodynamic analysis module uses a three-dimensional non-structural solver based on the finite volume method to simulate and calculate the aerodynamic data of the flying wing layout aircraft landing gear cover under the influence of each state; The retracting and extending process of the landing gear cover of the flying wing aircraft is divided into 6 states: State0 is the state without landing gear cover interference; State 1 is the state where the front hatch cover and the main hatch cover are fully opened; State2 is the state where all front hatch covers are open and all main hatch covers are closed; State3 is the state where the front hatch covers are all closed and the main hatch covers are all opened; State 4 is the state where all front hatch covers are opened, the left main hatch cover A and the right main hatch cover A are closed, and the left main hatch cover B and the right main hatch cover B are opened; State 5 is a state in which the front hatch cover and the left main hatch cover are all closed, and the right main hatch cover is all opened.

7. The flying wing aircraft landing gear retraction and extension optimization control system according to claim 6, characterized in that: The static instability analysis module is specifically configured to perform the following process: According to the aerodynamic data, a heading static stability derivative curve in the entire data packet curve in each state of the landing gear cover retraction and extension process of the flying wing layout aircraft is obtained; According to the degree of negative deviation of the heading static stability derivative curve in the entire data packet line under each state, the degree of deterioration of the heading static instability under each state is obtained and ranked.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

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