A method of determining crosswind capability of a three-point aircraft ground roll

Abstract

The application belongs to the field of aircraft maneuverability and stability design, and particularly relates to a method for determining crosswind resistance capability of a three-point aircraft during ground taxiing. The method comprises the following steps: S1, performing stress analysis and modeling on the aircraft during ground taxiing, and constructing a balance equation; S2, determining unknowns in each balance equation; S3, according to different working conditions of the aircraft during ground taxiing, assigning values to part of the unknowns to become known quantities, so that the number of unknowns is equal to the number of balance equations; S4, solving the balance equation, and judging whether the solving result meets a preset condition, if yes, the aircraft has the capability to resist the current crosswind speed, otherwise, the crosswind speed value is reduced to re-solve the balance equation until a solving result meeting the preset condition is obtained. The application can provide a calculation means and a judgment basis for whether the aircraft can carry out a ground taxiing test when encountering crosswind, and ensures the safety of the aircraft ground taxiing.

Description

Technical Field

[0001] This application belongs to the field of aircraft handling and stability design, and specifically relates to a method for determining the crosswind resistance of a tricycle aircraft during ground taxiing. Background Technology

[0002] Before its maiden flight, an aircraft needs to undergo ground taxiing tests to verify its performance and the functionality of its systems. These tests often involve crosswinds, necessitating an assessment of their impact on the aircraft.

[0003] Generally, when encountering crosswinds during the takeoff and landing phase, aerodynamic forces, reaction forces, and friction all change. Crosswinds alter the aircraft's aerodynamic characteristics, and the aircraft is also affected by reaction forces and ground friction. When the wind speed reaches a certain level, phenomena such as tipping and yaw may occur, leading to unsafe accidents such as wingtip strikes or runway overruns. Therefore, it is necessary to assess the aircraft's ability to withstand crosswinds during the ground takeoff and landing phase to determine whether the aircraft can taxi along the runway centerline under the current wind speed, thereby ensuring aircraft safety.

[0004] Therefore, there is an urgent need for a technical solution to overcome or mitigate at least one of the aforementioned defects in the existing technology. Summary of the Invention

[0005] The purpose of this application is to provide a method for determining the crosswind resistance of a tricycle aircraft during ground taxiing, in order to solve at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] A method for determining the crosswind resistance of a tricycle aircraft during ground taxiing includes:

[0008] Step S1: Perform force analysis and modeling on the aircraft during the ground taxiing phase, and construct the equilibrium equations;

[0009] Step S2: Determine the unknowns in each equilibrium equation;

[0010] Step S3: Based on the different operating conditions during the aircraft's ground taxiing phase, assign values ​​to some unknowns to transform them into known quantities, so that the number of unknowns is equal to the number of equilibrium equations.

[0011] Step S4: Solve the equilibrium equation and determine whether the solution meets the preset conditions. If yes, the aircraft has the ability to resist the current crosswind speed. Otherwise, reduce the crosswind speed value and solve the equilibrium equation again until a solution that meets the preset conditions is obtained.

[0012] In at least one embodiment of this application, step S1 involves performing force analysis and modeling on the aircraft during the ground taxiing phase, and constructing equilibrium equations, including:

[0013] During the aircraft's ground taxiing phase, the balance of normal force and longitudinal moment must be satisfied, and the equations for the balance of normal force and longitudinal moment must be constructed.

[0014] During the aircraft's ground taxiing phase, if the aircraft does not move laterally, then the lateral force balance is satisfied, and the lateral force balance equation is constructed.

[0015] During the aircraft's ground taxiing phase, ensuring that the aircraft does not yaw satisfies the heading moment balance, and the heading moment balance equation is constructed.

[0016] During the aircraft's ground taxiing phase, ensuring that the aircraft does not roll over satisfies the lateral moment balance, thus establishing the lateral moment balance equation.

[0017] In at least one embodiment of this application, the normal force balance equation is:

[0018] ;

[0019] Where G is the aircraft weight, CL is the rolling moment coefficient, q is the dynamic pressure, S is the wing reference area, and F... zhulunL For the left main wheel support reaction force, F zhulunR F is the reaction force of the right main wheel support. qianlun This is the reaction force of the front wheel support.

[0020] In at least one embodiment of this application, the longitudinal moment balance equation is:

[0021] ;

[0022] Where Cm is the pitching moment coefficient, cA is the mean aerodynamic chord length of the wing, and x CL F is the lever arm of the lift force relative to the center of gravity in the x-axis direction. T For engine thrust, z FT Let CD be the lever arm of the thrust relative to the center of gravity in the z-axis direction, and let CD be the drag coefficient. CD x is the lever arm of the resistance relative to the center of gravity in the z-axis direction. Fqianlun Let f be the lever arm of the front wheel support reaction force relative to the center of gravity in the x-axis direction, f be the rolling friction coefficient, and z be the force arm of the front wheel support reaction force. Fqianlun x is the lever arm of the front wheel support reaction force relative to the center of gravity in the z-axis direction. Fzhulun The lever arm of the main wheel's reaction force relative to the center of gravity along the x-axis is z. Fzhulun It is the lever arm of the main wheel support reaction force relative to the center of gravity in the z-axis direction.

[0023] In at least one embodiment of this application, the lateral force balance equation is:

[0024] ;

[0025] Where CY is the lateral force coefficient, fs1 is the lateral friction coefficient of the main wheel, and fs2 is the lateral friction coefficient of the front wheel.

[0026] In at least one embodiment of this application, the heading moment balance equation is:

[0027] ;

[0028] Where Cn is the yaw moment coefficient, b is the wingspan of the aircraft, and x CY It is the lever arm of the lateral force relative to the center of gravity in the x-axis direction.

[0029] In at least one embodiment of this application, the lateral moment balance equation is:

[0030] ;

[0031] Where Cl is the rolling moment coefficient, z CY Let y be the lever arm of the lateral force relative to the center of gravity in the z-axis direction. FzhulunL Let y be the lever arm of the left main wheel relative to its center of gravity along the y-axis. FzhulunR It is the lever arm of the right main wheel relative to the center of gravity in the y-axis direction.

[0032] In at least one embodiment of this application, step S2, determining the unknowns in each equilibrium equation, includes:

[0033] Determine the range of takeoff speed V∈[0,V] during the aircraft's ground takeoff phase. R Angle of attack α, sideslip angle β, engine thrust F T And obtain the preset crosswind speed value w, where V R To increase the speed of the front wheels, ;

[0034] In each equilibrium equation, the aerodynamic coefficients CL, CD, Cm, CY, Cn and Cl are all functions of the angle of attack α, sideslip angle β, elevator deflection de, rudder deflection dr and aileron deflection da;

[0035] Therefore, the unknowns in each equilibrium equation include the left main wheel support reaction force F. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficients of the main wheel (fs1), the lateral friction coefficients of the front wheel (fs2), the elevator deflection (de), the rudder deflection (dr), and the aileron deflection (da).

[0036] In at least one embodiment of this application, in step S3, according to different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values ​​to become known quantities, so that the number of unknowns is equal to the number of equilibrium equations, including:

[0037] The first working condition is: during the taxiing run, when encountering crosswinds, the friction force alone is used to balance the effects of the crosswinds without additional deflection of the ailerons and rudder.

[0038] Assign values ​​to the elevator deflection de, rudder deflection dr, and aileron deflection da, making them known quantities: de = dr = da = 0;

[0039] The unknown is the reaction force F of the left main wheel support. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficient of the main wheel is fs1, and the lateral friction coefficient of the front wheel is fs2.

[0040] In at least one embodiment of this application, in step S3, according to different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values ​​to become known quantities, so that the number of unknowns is equal to the number of equilibrium equations, including:

[0041] The second working condition is as follows: During the taxiing process, as the taxiing speed increases, the front wheel support reaction force becomes smaller and smaller, and the demand for the front wheel lateral friction coefficient becomes larger and larger. When the front wheel lateral friction coefficient is greater than the maximum lateral friction coefficient, the front wheel lateral friction is insufficient to balance the effect of the crosswind. At this time, the rudder is used to balance the yaw effect caused by the crosswind.

[0042] Assign values ​​to the front wheel lateral friction coefficient fs2, elevator deflection de, and aileron deflection da, transforming them into known quantities: fs2 = fs max , de=da=0, where, fs max The coefficient of maximum lateral friction.

[0043] The unknown is the reaction force F of the left main wheel support. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun , Main wheel lateral friction coefficient fs1, rudder deflection dr.

[0044] In at least one embodiment of this application, in step S3, according to different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values ​​to become known quantities, so that the number of unknowns is equal to the number of equilibrium equations, including:

[0045] Condition 3 is as follows: During the taxiing process, when the crosswind is greater than the preset threshold, the forces on the left and right main wheels are inconsistent. When the crosswind speed reaches a certain level, one side of the main wheel leaves the ground. After leaving the ground, the reaction force of the main wheel on that side becomes 0. At this time, the rolling effect caused by the crosswind is balanced by deflecting the aileron.

[0046] With the left main wheel off the ground: the reaction force F on the left main wheel zhulunLThe elevator deflection (de) and rudder deflection (dr) are assigned values ​​to become known quantities. zhulunL =de=dr=0; then the unknown is the reaction force F of the left and right wheel supports. zhulunR , Front wheel support reaction force F qianlun Main wheel lateral friction coefficient fs1, front wheel lateral friction coefficient fs2, aileron deflection da;

[0047] With the right main wheel off the ground: the support reaction force F on the right main wheel zhulunR The elevator deflection (de) and rudder deflection (dr) are assigned values ​​to become known quantities, F. zhulunR =de=dr=0; then the unknown is the left main wheel support reaction force F. zhulunL , Front wheel support reaction force F qianlun , Main wheel lateral friction coefficient fs1, front wheel lateral friction coefficient fs2, aileron deflection da.

[0048] In at least one embodiment of this application, in step S4, the preset condition is that the following conditions are met simultaneously:

[0049] Left main wheel support reaction force F zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun Greater than 0;

[0050] The lateral friction coefficients fs1 of the main wheel and fs2 of the front wheel are less than the maximum lateral friction coefficient.

[0051] The elevator deflection (de), rudder deflection (dr), and aileron deflection (da) are all less than the design deflection range.

[0052] The invention has at least the following beneficial technical effects:

[0053] The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing in this application can quickly and accurately calculate the crosswind resistance of a tricycle aircraft during ground taxiing, providing a calculation method and judgment basis for whether a ground taxiing test can be carried out when an aircraft encounters crosswinds, and ensuring the safety of the aircraft during ground taxiing. Attached Figure Description

[0054] Figure 1 This is a flowchart of a method for determining the crosswind resistance of a tricycle aircraft during ground taxiing, according to one embodiment of this application.

[0055] Figure 2 This is a schematic diagram of the force analysis of an aircraft during ground taxiing according to one embodiment of this application;

[0056] Figure 3 This is a schematic diagram illustrating the variation of the lateral friction coefficient of the main wheel with the running speed according to one embodiment of this application;

[0057] Figure 4 This is a schematic diagram illustrating the variation of the front wheel lateral friction coefficient with gliding speed according to one embodiment of this application;

[0058] Figure 5 This is a schematic diagram illustrating the change of support reaction force with running speed in one embodiment of this application;

[0059] Figure 6 This is a schematic diagram illustrating the change of rudder deflection with taxiing speed according to one embodiment of this application;

[0060] Figure 7 This is a schematic diagram illustrating the variation of the lateral friction coefficient of the main wheel with the running speed according to one embodiment of this application;

[0061] Figure 8 This is a schematic diagram illustrating the change of support reaction force with running speed in one embodiment of this application. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0063] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0064] The following is in conjunction with the appendix Figures 1 to 8 This application will be described in further detail.

[0065] During takeoff and landing rolls, the aircraft needs to complete the entire normal roll along the runway. Unlike the forces acting on an aircraft in the air, on the ground, in addition to gravity, thrust, and aerodynamic forces, the aircraft is also affected by ground reaction forces and ground friction. Therefore, during takeoff and landing rolls, the aircraft needs to meet the following conditions to ensure safe roll:

[0066] a) Crosswinds will not cause the aircraft to move laterally;

[0067] b) Crosswinds will not cause the aircraft to yaw;

[0068] c) Crosswinds will not cause the aircraft to roll.

[0069] To ensure that the above conditions are met, this application provides a method for determining the crosswind resistance of a tricycle aircraft during ground taxiing, such as... Figure 1 As shown, it includes the following steps:

[0070] Step S1: Perform force analysis and modeling on the aircraft during the ground taxiing phase, and construct the equilibrium equations;

[0071] Step S2: Determine the unknowns in each equilibrium equation;

[0072] Step S3: Based on the different operating conditions during the aircraft's ground taxiing phase, assign values ​​to some unknowns to transform them into known quantities, so that the number of unknowns is equal to the number of equilibrium equations.

[0073] Step S4: Solve the equilibrium equation and determine whether the solution meets the preset conditions. If yes, the aircraft has the ability to resist the current crosswind speed. Otherwise, reduce the crosswind speed value and solve the equilibrium equation again until a solution that meets the preset conditions is obtained.

[0074] The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing in this application, firstly, in step S1, analyzes the force situation of the aircraft during the taxiing phase, such as... Figure 1 As shown, the thrust, gravity, lift, drag, lateral force, ground reaction force, and friction of an aircraft need to satisfy force balance in the y-axis and z-axis directions, as well as torque balance in the x, y, and z axes. The force balance and torque balance formulas are derived to obtain five balance equations (1) to (5).

[0075] During the aircraft's ground taxiing phase, the balance of normal force and longitudinal moment must be satisfied, and the equations for the balance of normal force and longitudinal moment must be constructed.

[0076] The equation for the equilibrium of normal forces is:

[0077] (1);

[0078] Where G is the aircraft weight, CL is the rolling moment coefficient, q is the dynamic pressure, S is the wing reference area, and F... zhulunL For the left main wheel support reaction force, F zhulunR F is the reaction force of the right main wheel support. qianlun This is the reaction force of the front wheel support.

[0079] Dynamic pressure is Where ρ is the air density (kg / m³) 3 ).

[0080] The longitudinal moment balance equation is:

[0081] (2);

[0082] Where Cm is the pitching moment coefficient, cA is the mean aerodynamic chord length of the wing, and x CL F is the lever arm of the lift force relative to the center of gravity in the x-axis direction. T For engine thrust, z FT Let CD be the lever arm of the thrust relative to the center of gravity in the z-axis direction, and let CD be the drag coefficient. CD x is the lever arm of the resistance relative to the center of gravity in the z-axis direction. Fqianlun Let f be the lever arm of the front wheel support reaction force relative to the center of gravity in the x-axis direction, f be the rolling friction coefficient, and z be the force arm of the front wheel support reaction force. Fqianlun x is the lever arm of the front wheel support reaction force relative to the center of gravity in the z-axis direction. Fzhulun The lever arm of the main wheel's reaction force relative to the center of gravity along the x-axis is z. Fzhulun It is the lever arm of the main wheel support reaction force relative to the center of gravity in the z-axis direction.

[0083] During the aircraft's ground taxiing phase, if the aircraft does not move laterally, then the lateral force balance is satisfied, and the lateral force balance equation is constructed.

[0084] The lateral force equilibrium equations are:

[0085] (3);

[0086] Where CY is the lateral force coefficient, fs1 is the lateral friction coefficient of the main wheel, and fs2 is the lateral friction coefficient of the front wheel.

[0087] During the aircraft's ground taxiing phase, ensuring that the aircraft does not yaw satisfies the heading moment balance, and the heading moment balance equation is constructed.

[0088] The heading moment balance equation is:

[0089] (4);

[0090] Where Cn is the yaw moment coefficient, b is the wingspan of the aircraft, and x CY It is the lever arm of the lateral force relative to the center of gravity in the x-axis direction.

[0091] During the aircraft's ground taxiing phase, ensuring that the aircraft does not roll over satisfies the lateral moment balance, thus establishing the lateral moment balance equation.

[0092] The equation for lateral moment balance is:

[0093] (5);

[0094] Where Cl is the rolling moment coefficient, z CY Let y be the lever arm of the lateral force relative to the center of gravity in the z-axis direction. FzhulunL Let y be the lever arm of the left main wheel relative to its center of gravity along the y-axis. FzhulunR It is the lever arm of the right main wheel relative to the center of gravity in the y-axis direction.

[0095] During the takeoff and landing phase, the aircraft must first satisfy the balance between the normal force and the longitudinal moment, i.e., satisfy the balance equations shown in formulas (1) and (2). To prevent lateral movement, the aircraft must satisfy the balance of lateral forces, i.e., satisfy the balance equation shown in formula (3). To prevent yaw, the aircraft must satisfy the balance of directional moments, i.e., satisfy the balance equation shown in formula (4). To prevent rollover, the aircraft must satisfy the balance of lateral moments, i.e., satisfy the balance equation shown in formula (5). In summary, the aircraft must satisfy the above five equations during the ground takeoff and landing phase to ensure normal takeoff and landing.

[0096] The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing, as described in this application, includes step S2, which involves determining the unknowns in each equilibrium equation, including:

[0097] Determine the range of takeoff speed V∈[0,V] during the aircraft's ground takeoff phase. R Angle of attack α, sideslip angle β, engine thrust F T And obtain the preset crosswind speed value w, where V R To increase the speed of the front wheels, ;

[0098] In each equilibrium equation, the aerodynamic coefficients CL, CD, Cm, CY, Cn and Cl are all functions of the angle of attack α, sideslip angle β, elevator deflection de, rudder deflection dr and aileron deflection da;

[0099] Therefore, the unknowns in each equilibrium equation include the left main wheel support reaction force F. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficients of the main wheel (fs1), the lateral friction coefficients of the front wheel (fs2), the elevator deflection (de), the rudder deflection (dr), and the aileron deflection (da).

[0100] The speed range can be adjusted according to actual conditions. The sideslip angle β can be determined based on the crosswind speed and takeoff speed, while the angle of attack α can be determined based on the aircraft's geometric parameters and its geometric relationship with the ground. Engine thrust F T The values ​​are constants during takeoff and landing rolls. There are a total of 8 unknowns, 3 more than the formula. Therefore, the unknowns need to be selected according to the actual operating conditions to ensure that the equilibrium equations are consistent with the unknowns, thus obtaining a unique solution.

[0101] Therefore, in step S3, based on the different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values ​​and transformed into known quantities, so that the number of unknowns equals the number of equilibrium equations, including:

[0102] The first working condition is: during the taxiing run, when encountering crosswinds, the friction force alone is used to balance the effects of the crosswinds without additional deflection of the ailerons and rudder.

[0103] Assign values ​​to the elevator deflection de, rudder deflection dr, and aileron deflection da, making them known quantities: de = dr = da = 0;

[0104] The unknown is the reaction force F of the left main wheel support. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficient of the main wheel is fs1, and the lateral friction coefficient of the front wheel is fs2.

[0105] The second working condition is as follows: During the taxiing process, as the taxiing speed increases, the front wheel support reaction force becomes smaller and smaller, and the demand for the front wheel lateral friction coefficient becomes larger and larger. When the front wheel lateral friction coefficient is greater than the maximum lateral friction coefficient, the front wheel lateral friction is insufficient to balance the effect of the crosswind. At this time, the rudder is used to balance the yaw effect caused by the crosswind.

[0106] Assign values ​​to the front wheel lateral friction coefficient fs2, elevator deflection de, and aileron deflection da, transforming them into known quantities: fs2 = fs max , de=da=0, where, fs max The coefficient of maximum lateral friction.

[0107] The unknown is the reaction force F of the left main wheel support. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun , Main wheel lateral friction coefficient fs1, rudder deflection dr.

[0108] Condition 3 is as follows: During the taxiing process, when the crosswind is greater than the preset threshold, the forces on the left and right main wheels are inconsistent. When the crosswind speed reaches a certain level, one side of the main wheel leaves the ground. After leaving the ground, the reaction force of the main wheel on that side becomes 0. At this time, the rolling effect caused by the crosswind is balanced by deflecting the aileron.

[0109] With the left main wheel off the ground: the reaction force F on the left main wheel zhulunL The elevator deflection (de) and rudder deflection (dr) are assigned values ​​to become known quantities, F. zhulunL =de=dr=0; then the unknown is the reaction force F of the left and right wheel supports. zhulunR , Front wheel support reaction force F qianlun Main wheel lateral friction coefficient fs1, front wheel lateral friction coefficient fs2, aileron deflection da;

[0110] With the right main wheel off the ground: the support reaction force F on the right main wheel zhulunR The elevator deflection (de) and rudder deflection (dr) are assigned values ​​to become known quantities, F. zhulunR =de=dr=0; then the unknown is the left main wheel support reaction force F. zhulunL , Front wheel support reaction force F qianlun , Main wheel lateral friction coefficient fs1, front wheel lateral friction coefficient fs2, aileron deflection da.

[0111] Finally, in step S4, the five equilibrium equations (1) to (5) are solved according to the different working conditions described above to obtain the left main wheel support reaction force F. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The results of solving for the lateral friction coefficients fs1 (main wheel), fs2 (front wheel), elevator deflection de, rudder deflection dr, and aileron deflection da are then determined. Next, it is judged whether the results meet the preset conditions. If the following conditions are met simultaneously:

[0112] Left main wheel support reaction force F zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun Greater than 0;

[0113] The lateral friction coefficients fs1 of the main wheel and fs2 of the front wheel are less than the maximum lateral friction coefficient fs. max ;

[0114] The elevator deflection (de), rudder deflection (dr), and aileron deflection (da) are all less than the design deflection range.

[0115] This indicates that within the calculated takeoff speed range, the aircraft has the ability to resist the current crosswind speed. Otherwise, reduce the crosswind speed value and resolve the equilibrium equation until a solution that meets the preset conditions is obtained.

[0116] The solution results are analyzed as follows:

[0117] If all support reaction forces are greater than 0 and the lateral friction coefficients are all less than the maximum value, then the aircraft does not need to deflect the control surfaces and can balance the effects of crosswinds solely through its own friction.

[0118] If the left main wheel supports a reaction force F zhulunL Or the right main wheel support reaction force F zhulunR If the value is less than 0, it means that the aircraft cannot achieve lateral balance on its own under the current wind speed. The ailerons need to be deflected to overcome some of the roll moment brought by the crosswind. In this case, the unknowns should be selected according to working condition 3. If the aileron deflection da obtained by the solution does not exceed the predetermined design deflection range, it means that the aircraft has sufficient ability to resist the roll brought by the crosswind.

[0119] If the front wheel lateral friction coefficient fs2 is greater than the maximum lateral friction coefficient fs max If the lateral friction of the front wheel is insufficient to balance the yaw moment caused by the crosswind, the rudder needs to be used to resist part of the yaw moment caused by the crosswind in order to maintain the heading balance of the aircraft. In this case, the unknowns should be selected according to the second working condition. If the rudder deflection dr obtained by the solution does not exceed the predetermined design deflection range, it means that the aircraft has sufficient ability to resist the yaw caused by the crosswind.

[0120] If the aileron deflection da or rudder deflection dr exceeds the corresponding design deflection range, it means that under the current crosswind conditions, the aircraft cannot resist the negative effects of the crosswind. It is necessary to reduce the crosswind speed and repeat the above calculation process until a wind speed that meets the requirements is found.

[0121] In one specific embodiment of this application, it is assumed that the aircraft encounters a 10m crosswind and the maximum lateral friction coefficient is 0.5.

[0122] First, using operating condition one, i.e. the aircraft does not deflect the control surface, de=dr=da=0, the unknown left main wheel support reaction force F is solved according to equations (1) to (5). zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficients fs1 (main wheel) and fs2 (nose wheel) are used to calculate the aircraft's ability to maintain lateral balance. The calculation results are shown in Figure 3. Figure 5 As shown, the support reaction force remains positive throughout the takeoff speed range, therefore, there is no rollover under a crosswind of 10 m / s. When the speed exceeds 216 km / h, the support reaction force is already small, and the corresponding lateral friction of the front wheel is also very small. This is insufficient to maintain the lateral friction required for heading balance, so the demand for the front wheel lateral friction coefficient exceeds the maximum value of 0.5. At this point, a moving control surface is needed to compensate for the insufficient front wheel friction.

[0123] Once the speed exceeds 216 km / h, the rudder is deflected to compensate for the directional asymmetric moment. At this point, the method for determining the unknown in Case 2 is used, i.e., the unknown is selected as the left main wheel support reaction force F. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun Given the main wheel lateral friction coefficient fs1, rudder deflection dr, and given fs2 = 0.5, de = da = 0, solve the equilibrium equations. The calculation results are as follows: Figures 6-8 As shown, the reaction forces of the main wheels are all greater than 0, the lateral friction coefficient of the main wheels is much smaller than the maximum value, the maximum rudder deflection is 10.4°, and the design range is 25°. Therefore, the rudder deflection does not exceed the design range.

[0124] In summary, during the ground taxiing phase, the aircraft is capable of withstanding crosswinds of 10 m / s.

[0125] The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing in this application can determine the crosswind resistance of an unmanned aerial vehicle (UAV), providing calculation methods and judgment criteria for whether a tricycle aircraft can conduct ground taxiing tests when encountering crosswinds, thus ensuring aircraft safety.

[0126] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining the crosswind resistance of a tricycle aircraft during ground taxiing, characterized in that, include: Step S1: Perform force analysis and modeling on the aircraft during the ground taxiing phase, and construct the equilibrium equations; Step S2: Determine the unknowns in each equilibrium equation; Step S3: Based on the different operating conditions during the aircraft's ground taxiing phase, assign values ​​to some unknowns to transform them into known quantities, so that the number of unknowns is equal to the number of equilibrium equations. Step S4: Solve the equilibrium equation and determine whether the solution meets the preset conditions. If yes, the aircraft has the ability to resist the current crosswind speed. Otherwise, reduce the crosswind speed value and solve the equilibrium equation again until a solution that meets the preset conditions is obtained.

2. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 1, characterized in that, In step S1, force analysis and modeling are performed on the aircraft during the ground taxiing phase, and equilibrium equations are constructed, including: During the aircraft's ground taxiing phase, the balance of normal force and longitudinal moment must be satisfied, and the equations for the balance of normal force and longitudinal moment must be constructed. During the aircraft's ground taxiing phase, if the aircraft does not move laterally, then the lateral force balance is satisfied, and the lateral force balance equation is constructed. During the aircraft's ground taxiing phase, ensuring that the aircraft does not yaw satisfies the heading moment balance, and the heading moment balance equation is constructed. During the aircraft's ground taxiing phase, ensuring that the aircraft does not roll over satisfies the lateral moment balance, thus establishing the lateral moment balance equation.

3. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 2, characterized in that, The equation for the equilibrium of normal forces is: ； Where G is the aircraft weight, CL is the rolling moment coefficient, q is the dynamic pressure, S is the wing reference area, and F... zhulunL For the left main wheel support reaction force, F zhulunR F is the reaction force of the right main wheel support. qianlun This is the reaction force of the front wheel support.

4. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 3, characterized in that, The longitudinal moment balance equation is: ； Where Cm is the pitching moment coefficient, cA is the mean aerodynamic chord length of the wing, and x CL F is the lever arm of the lift force relative to the center of gravity in the x-axis direction. T For engine thrust, z FT Let CD be the lever arm of the thrust relative to the center of gravity in the z-axis direction, and let CD be the drag coefficient. CD x is the lever arm of the resistance relative to the center of gravity in the z-axis direction. Fqianlun Let f be the lever arm of the front wheel support reaction force relative to the center of gravity in the x-axis direction, f be the rolling friction coefficient, and z be the force arm of the front wheel support reaction force. Fqianlun x is the lever arm of the front wheel support reaction force relative to the center of gravity in the z-axis direction. Fzhulun The lever arm of the main wheel's reaction force relative to the center of gravity along the x-axis is z. Fzhulun It is the lever arm of the main wheel support reaction force relative to the center of gravity in the z-axis direction.

5. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 4, characterized in that, The lateral force equilibrium equations are: ； Where CY is the lateral force coefficient, fs1 is the lateral friction coefficient of the main wheel, and fs2 is the lateral friction coefficient of the front wheel.

6. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 5, characterized in that, The heading moment balance equation is: ； Where Cn is the yaw moment coefficient, b is the wingspan of the aircraft, and x CY It is the lever arm of the lateral force relative to the center of gravity in the x-axis direction.

7. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 6, characterized in that, The equation for lateral moment balance is: ； Where Cl is the rolling moment coefficient, z CY Let y be the lever arm of the lateral force relative to the center of gravity in the z-axis direction. FzhulunL Let y be the lever arm of the left main wheel relative to its center of gravity along the y-axis. FzhulunR It is the lever arm of the right main wheel relative to the center of gravity in the y-axis direction.

8. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 7, characterized in that, In step S2, the unknowns in each equilibrium equation are determined, including: Determine the range of takeoff speed V∈[0,V] during the aircraft's ground takeoff phase. R Angle of attack α, sideslip angle β, engine thrust F T And obtain the preset crosswind speed value w, where V R To increase the speed of the front wheels, ; In each equilibrium equation, the aerodynamic coefficients CL, CD, Cm, CY, Cn and Cl are all functions of the angle of attack α, sideslip angle β, elevator deflection de, rudder deflection dr and aileron deflection da; Therefore, the unknowns in each equilibrium equation include the left main wheel support reaction force F. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficients of the main wheel (fs1), the lateral friction coefficients of the front wheel (fs2), the elevator deflection (de), the rudder deflection (dr), and the aileron deflection (da).

9. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 8, characterized in that, In step S3, based on the different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values, transforming them into known quantities, so that the number of unknowns equals the number of equilibrium equations, including: The first working condition is: during the taxiing run, when encountering crosswinds, the friction force alone is used to balance the effects of the crosswinds without additional deflection of the ailerons and rudder. Assign values ​​to the elevator deflection de, rudder deflection dr, and aileron deflection da, making them known quantities: de = dr = da = 0; The unknown is the reaction force F of the left main wheel support. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun The lateral friction coefficient of the main wheel is fs1, and the lateral friction coefficient of the front wheel is fs2.

10. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 9, characterized in that, In step S3, based on the different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values, transforming them into known quantities, so that the number of unknowns equals the number of equilibrium equations, including: The second working condition is as follows: During the taxiing process, as the taxiing speed increases, the front wheel support reaction force becomes smaller and smaller, and the demand for the front wheel lateral friction coefficient becomes larger and larger. When the front wheel lateral friction coefficient is greater than the maximum lateral friction coefficient, the front wheel lateral friction is insufficient to balance the effect of the crosswind. At this time, the rudder is used to balance the yaw effect caused by the crosswind. Assign values ​​to the front wheel lateral friction coefficient fs2, elevator deflection de, and aileron deflection da, transforming them into known quantities: fs2 = fs max , de=da=0, where, fs max The coefficient of maximum lateral friction. The unknown is the reaction force F of the left main wheel support. zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun , Main wheel lateral friction coefficient fs1, rudder deflection dr.

11. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 10, characterized in that, In step S3, based on the different operating conditions during the aircraft's ground taxiing phase, some unknowns are assigned values, transforming them into known quantities, so that the number of unknowns equals the number of equilibrium equations, including: Condition 3 is as follows: During the taxiing process, when the crosswind is greater than the preset threshold, the forces on the left and right main wheels are inconsistent. When the crosswind speed reaches a certain level, one side of the main wheel leaves the ground. After leaving the ground, the reaction force of the main wheel on that side becomes 0. At this time, the rolling effect caused by the crosswind is balanced by deflecting the aileron. With the left main wheel off the ground: the reaction force F on the left main wheel zhulunL The elevator deflection (de) and rudder deflection (dr) are assigned values ​​to become known quantities, F. zhulunL =de=dr=0; then the unknown is the reaction force F of the left and right wheel supports. zhulunR , Front wheel support reaction force F qianlun Main wheel lateral friction coefficient fs1, front wheel lateral friction coefficient fs2, aileron deflection da; With the right main wheel off the ground: the support reaction force F on the right main wheel zhulunR The elevator deflection (de) and rudder deflection (dr) are assigned values ​​to become known quantities, F. zhulunR =de=dr=0; then the unknown is the left main wheel support reaction force F. zhulunL , Front wheel support reaction force F qianlun , Main wheel lateral friction coefficient fs1, front wheel lateral friction coefficient fs2, aileron deflection da.

12. The method for determining the crosswind resistance of a tricycle aircraft during ground taxiing according to claim 11, characterized in that, In step S4, the preset condition is that the following conditions must be met simultaneously: Left main wheel support reaction force F zhulunL , right main wheel reaction force F zhulunR , Front wheel support reaction force F qianlun Greater than 0; The lateral friction coefficients fs1 of the main wheel and fs2 of the front wheel are less than the maximum lateral friction coefficient fs. max ; The elevator deflection (de), rudder deflection (dr), and aileron deflection (da) are all less than the design deflection range.

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