A method for simulating and analyzing aircraft takeoff performance in multiple environmental variable coupling
Patent Information
- Application Number
- CN202611468385.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-21
- Publication Date
- 2026-10-27
AI Technical Summary
[0004]本发明提供一种多环境变量耦合的飞机起飞性能仿真分析方法，以至少解决现有技术中无法对多环境变量耦合作用下的飞机起飞滑跑过程进行全面量化评估的问题
本申请提供的多环境变量耦合的飞机起飞性能仿真分析方法中，基于多环境变量耦合的飞机起飞性能仿真分析方法，通过构建包含飞机物理参数与起飞环境参数的仿真动力学参数空间，并在此基础上解算离地真速、构建飞机滑跑受力平衡方程，为起飞滑跑距离基准值提供了统一的量化基准，为多因素扰动分析构建了标准化的参考。
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Figure CN122987223A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aviation simulation technology, and in particular relates to a simulation analysis method for aircraft takeoff performance coupled with multiple environmental variables. Background Technology
[0002] Aircraft takeoff is a complex and systematic process involving aerodynamics, power engineering, and human control. With the rapid development of the air transport industry and the continuous increase in flight takeoff and landing density, coupled with the growing number of complex operating environments such as high-altitude airports and short runways, higher demands are placed on the accurate assessment and safety simulation of takeoff performance. Against this backdrop, the aviation industry urgently needs a technical solution capable of high-performance simulation and analysis of the entire process from ground taxiing to takeoff to assist in engineering development, flight training, and operational safety assessment.
[0003] However, most existing takeoff performance simulation analysis technologies focus on single-dimensional physical calculations or rely on experience-based operational instruction, which falls short of the growing demand for comprehensive simulation and hinders further improvements in takeoff safety and training effectiveness. When faced with environmental changes that may occur during actual takeoff, such as changes in air density, fluctuations in engine thrust, the presence of runway slope, or changes in wind speed and direction, existing technologies struggle to systematically and automatically inject and iteratively evaluate these variables within the same dynamic model framework. Consequently, they cannot intuitively reflect the degree of influence of various environmental factors on takeoff distance and are unable to obtain accurate and comprehensive quantitative evaluation results. Summary of the Invention
[0004] This invention provides a simulation analysis method for aircraft takeoff performance under the coupling of multiple environmental variables, which at least solves the problem in the prior art that it is impossible to comprehensively quantify and evaluate the aircraft takeoff and taxiing process under the coupling of multiple environmental variables.
[0005] This application provides a simulation analysis method for aircraft takeoff performance coupled with multiple environmental variables, the method comprising: Step S1: Obtain the aircraft's physical parameters and takeoff environment parameters, and construct the simulation dynamics parameter space; Step S2: Based on the simulation dynamic parameters, calculate the true air velocity at takeoff, construct the force balance equation of the aircraft taxiing run, calculate the average equivalent friction coefficient and average acceleration of the taxiing run, and obtain the reference value of the takeoff taxiing run distance; Step S3: Inject multidimensional environmental variable disturbance vectors into the aircraft taxiing force balance equation, resolve the aircraft taxiing force balance equation based on the multidimensional environmental variable disturbance vectors, obtain the disturbed takeoff taxiing distance, recalculate through control variable iteration, and output the relative change of takeoff taxiing distance relative to the takeoff taxiing distance reference value under the action of each environmental variable. Step S4: Based on the true air-to-ground speed, compare the received virtual control speed ratio with the preset front wheel lift timing threshold range, and output the front wheel lift timing compliance judgment result; when the front wheel lift timing is determined to be non-compliant, output the corresponding aerodynamic penalty amount; when the front wheel lift timing is determined to be compliant, compare the skid lift coefficient with the favorable lift coefficient, and output the skid attitude evaluation result. Step S5: Calculate the sideslip angle and angle of attack under crosswind conditions in real time to determine the abnormal takeoff result of the aircraft; Step S6: Output the analysis results, which include relative changes, taxiing attitude assessment results, and aircraft takeoff anomaly results.
[0006] Furthermore, in step S1, the physical parameters include aircraft weight, engine thrust, wing area, and the maximum lift coefficient corresponding to the angle of attack at ground clearance; The takeoff environmental parameters include the ground friction coefficient and air density.
[0007] Further, in step S2, the true velocity at takeoff is calculated based on the simulated dynamic parameter space, and its expression is:
[0008] in, This is the true speed at takeoff. For the weight of the aircraft; Wing area; air density; This represents the maximum lift coefficient corresponding to the angle of attack at ground clearance.
[0009] Further, in step S2, the expression for the average equivalent friction coefficient during sliding is:
[0010] in, The average aerodynamic drag during the gliding run; For ground wheel friction; For the weight of the aircraft; The expression for the frictional force of the ground wheels is:
[0011] in, The coefficient of friction of the ground; This represents the average lift during the gliding run; The expression for the average aerodynamic drag during the glide is:
[0012] in, air density; Wing area; Zero-lift drag coefficient; The lift coefficient during the gliding run; Oswald efficiency factor; The aspect ratio of the wing; The average speed during the gliding run is taken as the true speed at takeoff. One-half; The expression for the average acceleration during gliding is:
[0013] in, This refers to the average acceleration during the gliding run; It is the acceleration due to gravity; For engine thrust; The expression for the takeoff run distance reference value is:
[0014] in, This is the baseline value for takeoff run distance; This is the true speed at takeoff. This represents the average acceleration during the gliding run.
[0015] Furthermore, in step S3, the multidimensional environmental variable disturbance vector includes: engine thrust change, aircraft load change, air density attenuation, headwind speed vector, and runway downhill angle. A multi-dimensional environmental variable disturbance vector is injected into the aircraft's takeoff run force balance equation. Based on the multi-dimensional environmental variable disturbance vector, the aircraft's takeoff run force balance equation is resolved to obtain the disturbed takeoff run distance. Specifically, this includes: When the air density decay is injected, the true air speed is recalculated according to the expression for the true air speed, and the average aerodynamic drag of the runway is updated to obtain the takeoff runway distance after the air density decay disturbance. When injecting the downhill angle of the runway At that time, the gravitational component introduced by the runway downhill is converted into an equivalent thrust increment, and the takeoff distance after the downhill angle disturbance is obtained by resolving the expression based on the modified average acceleration expression. The expression is as follows:
[0016] in, This is the corrected average acceleration during the gliding run; It is the acceleration due to gravity; For engine thrust; The average equivalent friction coefficient during gliding; This is the equivalent thrust increment; For the weight of the aircraft; The angle of the runway downhill; When the headwind speed vector is injected, the takeoff distance after headwind disturbance is obtained by resolving the problem based on the headwind-corrected ground speed; the expression for the headwind-corrected ground speed is:
[0017] in, This is the ground speed after headwind correction; This is the true speed at takeoff. Headwind speed; The expression for the takeoff distance after coupling headwind is:
[0018] in, This refers to the takeoff run distance after coupling with the headwind; This refers to the average acceleration during the gliding run; This is the true speed at takeoff. This refers to the headwind speed.
[0019] Further, in step S3, by iteratively recalculating the control variables, the relative change of the takeoff run distance relative to the baseline takeoff run distance under the influence of each environmental variable is output, specifically including: Using a controlled variable iterative approach, each time all parameters except the current environmental variable are kept constant, only the current environmental variable or its preset combination are changed, and the corresponding takeoff distance after disturbance is re-solved. The takeoff distance after each disturbance is compared with the baseline takeoff distance to calculate the relative change, which is expressed as follows:
[0020] in, It is a relative change. This refers to the takeoff distance after the disturbance. This is the baseline value for takeoff run distance.
[0021] Further, in step S4, the expression for the virtual manipulation speed ratio is:
[0022] in, The percentage of virtual manipulation speed; The airspeed at which the pilot performs the nose wheel lift maneuver; This is the true speed at takeoff. When the proportion of virtual control speed is less than the lower limit of the preset front wheel lift timing threshold range, it is determined to be premature front wheel lift; when the proportion of virtual control speed is greater than the upper limit of the preset front wheel lift timing threshold range, it is determined to be late front wheel lift; when the proportion of virtual control speed is greater than or equal to the lower limit of the preset front wheel lift timing threshold range and less than or equal to the upper limit of the preset front wheel lift timing threshold range, it is determined to be compliant with the front wheel lift timing. The expression for the pneumatic penalty is:
[0023] in, air density; Current flight speed; Wing area; This is the current lift coefficient; Oswald efficiency factor; The aspect ratio of the wing; The favorable lift coefficient is calculated using the following expression:
[0024] in, To achieve a favorable lift coefficient; It is the induced resistance factor; is the coefficient of friction of the ground.
[0025] Furthermore, in step S4, when it is determined that the timing of lifting the front wheels is compliant, the gliding lift coefficient is compared with the favorable lift coefficient, and the gliding attitude evaluation result is output, specifically including: Extract the real-time lift coefficient of the aircraft during the current taxiing state. The real-time lift coefficient With favorable lift coefficient The attitude deviation rate was calculated by comparison, and its expression is as follows:
[0026] in, This refers to the attitude deviation rate. This represents the real-time lift coefficient during the current taxiing phase. To achieve a favorable lift coefficient; According to the attitude deviation rate The relationship between the gliding attitude and the preset deviation threshold range is used to output the gliding attitude evaluation results: If the judgment If the optimal posture is achieved, the optimal evaluation result will be output. If the judgment and If the output is too large, the evaluation result will be too large. If the judgment If the output is too small, the evaluation result will be too small.
[0027] Furthermore, in step S5, the sideslip angle and angle of attack under crosswind conditions are calculated in real time to determine abnormal takeoff results, including: The sideslip angle is calculated using the following expression:
[0028]
[0029] in, This represents the vertical component of the crosswind; This represents the average speed during the gliding run; Crosswind speed; The crosswind angle; The sideslip angle Compared with the preset sideslip angle alarm threshold Compare; if determined If so, the result of the judgment on the crosswind deflection anomaly will be output; After the aircraft takes off, the lateral friction of the wheels disappears, and the steady-state yaw angle is recalculated. Its expression is:
[0030] in, To stabilize the deflection angle; The stable deflection angle With the sideslip angle alarm threshold Compare; if determined Then the result of the crosswind deflection anomaly judgment will be output.
[0031] Furthermore, in step S5, the real-time calculation of the sideslip angle and angle of attack under crosswind conditions, and the determination of abnormal aircraft takeoff results, also include: The critical angle of attack is calculated, and its expression is as follows:
[0032] in, This is the critical angle of attack; This represents the maximum lift coefficient corresponding to the ground-flying angle of attack. The lift coefficient during the gliding run; The slope of the lift line; When the detected angle of attack of the runway Greater than the critical angle of attack The time was determined to be an abnormality of low speed takeoff.
[0033] As can be seen from the above technical solutions, the present invention has the following advantages: The multi-environmental variable coupled aircraft takeoff performance simulation analysis method provided in this application constructs a simulation dynamic parameter space that includes aircraft physical parameters and takeoff environment parameters. Based on this space, the true takeoff speed is calculated and the aircraft taxiing force balance equation is constructed. This provides a unified quantitative benchmark for the takeoff taxiing distance benchmark value and constructs a standardized reference for multi-factor disturbance analysis.
[0034] Based on the obtained baseline value of takeoff run distance, this application injects multi-dimensional environmental variable disturbance vectors into the aircraft run force balance equation, and recalculates the disturbed takeoff run distance through iterative recalculation of control variables. It also outputs the relative change of takeoff run distance relative to the baseline value under the action of each environmental variable, realizing automatic iterative calculation of multiple environmental disturbance factors under a unified dynamic model. This enables quantitative characterization of the influence of each environmental variable on takeoff run distance, improving the accuracy and efficiency of takeoff run distance assessment under multivariate coupling conditions.
[0035] This application uses the true takeoff speed as a benchmark, compares the received virtual control speed ratio with the preset nose wheel lift timing threshold range, and outputs the nose wheel lift timing compliance judgment result. It incorporates the pilot's control behavior into the evaluation system of takeoff performance simulation analysis, so that the simulation analysis of takeoff performance is no longer limited to physical parameter calculation, but can quantitatively identify control timing deviations such as lifting the nose wheel too early or too late, filling the technical gap of lack of timing linkage between physical calculation and control behavior. Attached Figure Description
[0036] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0037] Figure 1 This is a flowchart of the aircraft takeoff performance simulation analysis method with multiple environmental variables coupled according to the present invention.
[0038] Figure 2 This is a schematic diagram of the physical model of the takeoff run force in the multi-environmental variable coupled aircraft takeoff performance simulation analysis method described in this invention.
[0039] Figure 3 This is a schematic diagram of the force analysis for determining the timing of nose wheel lift and torque changes in the multi-environmental variable coupled aircraft takeoff performance simulation analysis method described in this invention.
[0040] Figure 4This is a schematic diagram illustrating the forces involved in determining crosswind velocities and sideslip in the multi-environmental variable coupled aircraft takeoff performance simulation analysis method described in this invention.
[0041] Figure 5 This is a schematic diagram illustrating the velocity vector for determining crosswind velocities and sideslip in the multi-environmental variable coupled aircraft takeoff performance simulation analysis method described in this invention. Detailed Implementation
[0042] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0043] This application provides a simulation analysis method for aircraft takeoff performance under the coupling of multiple environmental variables, which solves the current urgent technical problem of comprehensively and quantitatively evaluating the takeoff performance of aircraft under the coupling of multiple environmental variables.
[0044] The technical solutions proposed in the embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0045] Figure 1 This is a flowchart illustrating a simulation analysis method for aircraft takeoff performance coupled with multiple environmental variables, provided as an embodiment of this application. Figure 1 As shown in the figure, the simulation analysis method for aircraft takeoff performance coupled with multiple environmental variables provided in this application embodiment specifically includes the following steps: Step S1: Obtain the aircraft's physical parameters and takeoff environment parameters, and construct the simulation dynamics parameter space; Step S2: Based on the simulation dynamic parameters, calculate the true air velocity at takeoff, construct the force balance equation of the aircraft taxiing run, calculate the average equivalent friction coefficient and average acceleration of the taxiing run, and obtain the reference value of the takeoff taxiing run distance; Step S3: Inject multidimensional environmental variable disturbance vectors into the aircraft taxiing force balance equation, resolve the aircraft taxiing force balance equation based on the multidimensional environmental variable disturbance vectors, obtain the disturbed takeoff taxiing distance, recalculate through control variable iteration, and output the relative change of takeoff taxiing distance relative to the takeoff taxiing distance reference value under the action of each environmental variable. Step S4: Based on the true air-to-ground speed, compare the received virtual control speed ratio with the preset front wheel lift timing threshold range, and output the front wheel lift timing compliance judgment result; when the front wheel lift timing is determined to be non-compliant, output the corresponding aerodynamic penalty amount; when the front wheel lift timing is determined to be compliant, compare the skid lift coefficient with the favorable lift coefficient, and output the skid attitude evaluation result. Step S5: Calculate the sideslip angle and angle of attack under crosswind conditions in real time to determine the abnormal takeoff result of the aircraft; Step S6: Output the analysis results, which include relative changes, taxiing attitude assessment results, and aircraft takeoff anomaly results.
[0046] It should be noted that in step S1, the physical parameters include aircraft weight, engine thrust, wing area, and the maximum lift coefficient corresponding to the angle of attack at ground clearance. The takeoff environmental parameters include the ground friction coefficient and air density.
[0047] In an exemplary embodiment, in step S2, the true velocity at takeoff is calculated based on the simulated dynamic parameter space, and its expression is:
[0048] in, This is the true speed off the ground; For the weight of the aircraft; Wing area; air density; This represents the maximum lift coefficient corresponding to the angle of attack at ground clearance.
[0049] According to another embodiment of the present invention, in step S2, the expression for the average equivalent friction coefficient of the skid is:
[0050] in, The average aerodynamic drag during the gliding run; For ground wheel friction; For the weight of the aircraft; The expression for the frictional force of the ground wheels is:
[0051] in, The coefficient of friction of the ground; This represents the average lift during the gliding run; The expression for the average aerodynamic drag during the glide is:
[0052] in, air density; Wing area; Zero-lift drag coefficient; The lift coefficient during the gliding run; Oswald efficiency factor; The aspect ratio of the wing; The average speed during the gliding run is taken as the true speed at takeoff. One-half; The expression for the average acceleration during gliding is:
[0053] in, This refers to the average acceleration during the gliding run; It is the acceleration due to gravity; For engine thrust; The expression for the takeoff roll distance reference value is:
[0054] in, This is the baseline value for takeoff run distance; This is the true speed off the ground; This represents the average acceleration during the gliding run.
[0055] Estimating the baseline value for the takeoff air segment distance using the principle of energy conservation includes: By setting a safe takeoff altitude and a speed at that altitude, and combining this with the average residual thrust ratio, the baseline value for the takeoff air segment distance is calculated using the energy conservation equation. The expression for this value is:
[0056] in, This serves as the baseline value for the takeoff air segment distance; For the safe altitude, the speed is set to 1.2 times the true speed off the ground; It is the acceleration due to gravity; This is the true speed off the ground; The average remaining thrust ratio represents the proportion of remaining thrust used to overcome gravity during the climb (an empirical value is set to 0.25).
[0057] According to an embodiment of this application, in step S3, the multidimensional environmental variable disturbance vector includes: engine thrust change, aircraft load change, air density attenuation, headwind speed vector, and runway downhill angle. A multi-dimensional environmental variable disturbance vector is injected into the aircraft's takeoff run force balance equation. Based on the multi-dimensional environmental variable disturbance vector, the aircraft's takeoff run force balance equation is resolved to obtain the disturbed takeoff run distance. Specifically, this includes: For each environmental variable in the multidimensional environmental variable disturbance vector, the aircraft taxiing force balance equation is injected one by one, and the takeoff taxiing distance after disturbance corresponding to each environmental variable is solved again; where: When the air density decay is injected, the true air speed is recalculated according to the expression for the true air speed, and the average aerodynamic drag of the runway is updated to obtain the takeoff runway distance after the air density decay disturbance. Air density from the baseline value Attenuation to According to the formula for true airspeed, the true airspeed after perturbation is:
[0058] in, The true velocity off the ground after the disturbance. For the weight of the aircraft, For wing area, The density of air after attenuation. This represents the maximum lift coefficient corresponding to the angle of attack at ground clearance.
[0059] The updated mean aerodynamic drag for gliding is derived from changes in air density and is expressed as follows:
[0060] in, The updated average speed is calculated by taking half of the true speed off the ground after the perturbation. .
[0061] The updated equivalent friction coefficient and mean acceleration are based on the updated drag and the perturbed mean equivalent friction coefficient of the run. and average acceleration during gliding They are respectively:
[0062]
[0063] The takeoff distance after the air density attenuation disturbance is obtained based on the baseline takeoff distance formula. The expression is: .
[0064] When injecting the downhill angle of the runway At that time, the gravitational component introduced by the runway downhill slope is converted into an equivalent thrust increment, and the takeoff distance after the downhill angle disturbance is obtained by resolving the expression based on the modified average acceleration expression. The expression is as follows:
[0065] in, This is the corrected average acceleration during the gliding run; It is the acceleration due to gravity; For engine thrust; The average equivalent friction coefficient during gliding; This is the equivalent thrust increment; For the weight of the aircraft; The angle of the runway downhill; When the headwind speed vector is injected, the takeoff distance after headwind disturbance is obtained by resolving the problem based on the headwind-corrected ground speed; the expression for the headwind-corrected ground speed is:
[0066] in, This is the ground speed after headwind correction; This is the true speed off the ground; Headwind speed; The expression for the takeoff distance after coupling headwind is:
[0067] in, This refers to the takeoff run distance after coupling with the headwind; This is the average acceleration during the gliding run; This is the true speed off the ground; Headwind speed; The expression for the reduction in takeoff distance is:
[0068] in, This is the reduction in takeoff run distance.
[0069] In one embodiment, step S3 involves iteratively recalculating the control variables to output the relative change in takeoff distance relative to the baseline takeoff distance under the influence of each environmental variable. Specifically, this includes: Using a controlled variable iterative approach, each time all parameters except the current environmental variable are kept constant, only the current environmental variable or its preset combination are changed, and the corresponding takeoff distance after disturbance is re-solved. The takeoff distance after each disturbance is compared with the baseline takeoff distance to calculate the relative change, which is expressed as follows:
[0070] in, It is a relative change. This refers to the takeoff distance after the disturbance. This is the baseline value for takeoff run distance.
[0071] The relative changes under the influence of various environmental variables are summarized to generate a multi-factor sensitivity comparison array, which is output in the form of a visual bar chart comparison array.
[0072] As an example, in step S4, the expression for the virtual manipulation speed ratio is:
[0073] in, The percentage of virtual manipulation speed; The airspeed at which the pilot performs the nose wheel lift maneuver; This is the true speed off the ground; When the proportion of virtual control speed is less than the lower limit of the preset front wheel lift timing threshold range, it is determined to be premature front wheel lift; when the proportion of virtual control speed is greater than the upper limit of the preset front wheel lift timing threshold range, it is determined to be late front wheel lift; when the proportion of virtual control speed is greater than or equal to the lower limit of the preset front wheel lift timing threshold range and less than or equal to the upper limit of the preset front wheel lift timing threshold range, it is determined to be compliant with the front wheel lift timing. The expression for the pneumatic penalty is:
[0074] in, air density; Current flight speed; Wing area; This is the current lift coefficient; Oswald efficiency factor; The aspect ratio of the wing; The favorable lift coefficient is calculated using the following expression:
[0075] in, The favorable lift coefficient is the lift coefficient that minimizes the total drag of the aircraft during takeoff. It is the induced resistance factor; is the coefficient of friction of the ground.
[0076] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, another method is provided to fully illustrate the specific implementation process in this embodiment. In step S4, when it is determined that the timing of lifting the front wheels is compliant, the skid lift coefficient is compared with the favorable lift coefficient, and the skid attitude evaluation result is output, specifically including: Extract the real-time lift coefficient of the aircraft during the current taxiing state. The real-time lift coefficient With favorable lift coefficient The attitude deviation rate was calculated through comparison, and its expression is as follows:
[0077] in, This refers to the attitude deviation rate. This represents the real-time lift coefficient during the current taxiing phase. To achieve a favorable lift coefficient; According to the attitude deviation rate The relationship between the gliding attitude and the preset deviation threshold range is used to output the gliding attitude evaluation results: If the judgment If the optimal attitude is output, it means that the current taxiing lift coefficient is close to the favorable lift coefficient, the taxiing acceleration efficiency is the highest, and the aerodynamic drag is the lowest. If the judgment and If the current angle of attack is too large, it will output an assessment result indicating that the current angle of attack is too large, causing the lift coefficient to exceed the favorable value, the induced drag to increase significantly, and there is a risk of deterioration of the lift-to-drag ratio and false sinking. It will also output an attitude correction prompt to reduce the angle of attack by the stabilizer bar. If the judgment If the output attitude assessment result is too small, it means that the current angle of attack is insufficient, it has not fully approached the optimal lift-to-drag ratio, and the acceleration efficiency of the taxiing is not optimal. The output prompts an attitude correction suggestion to appropriately increase the angle of attack by pulling the stick.
[0078] The gliding attitude evaluation result serves as the input data for the low-speed ground takeoff anomaly determination in step S5. When the attitude deviation rate continuously exceeds the limit and the lift coefficient approaches the maximum lift coefficient... At that time, the judgment of taking off at a low speed is triggered.
[0079] It should be further explained that in step S5, the sideslip angle and angle of attack under crosswind conditions are calculated in real time to determine the abnormal takeoff result of the aircraft, including: The sideslip angle is calculated using the following expression:
[0080]
[0081] in, This represents the vertical component of the crosswind; This represents the average speed during the gliding run; Crosswind speed; The crosswind angle; The sideslip angle Compared with the preset sideslip angle alarm threshold Compare; if determined If the crosswind deviation is abnormal, the output will be the judgment result, and based on the force balance relationship between the lateral friction of the wheel and the horizontal component of the crosswind, the output will be the control correction quantitative command to push the stick in the crosswind direction and push the rudder in the opposite direction. After the aircraft takes off, the lateral friction of the wheels disappears, and the steady-state yaw angle is recalculated. Its expression is:
[0082] in, To stabilize the deflection angle; The stable deflection angle With the sideslip angle alarm threshold Compare; if determined If the crosswind deviation anomaly is detected, the output result will be provided, and corresponding quantitative commands for lever and rudder correction to compensate for track deviation after takeoff will be generated.
[0083] In one embodiment, step S5, which involves real-time calculation of the sideslip angle and angle of attack under crosswind conditions to determine abnormal takeoff results, further includes: The critical angle of attack is calculated, and its expression is as follows:
[0084] in, This is the critical angle of attack; This represents the maximum lift coefficient corresponding to the ground-flying angle of attack. The lift coefficient during the gliding run; The slope of the lift line is determined by the ratio of the difference in lift coefficients of the linear segment of the lift curve to the corresponding difference in angle of attack. When the detected angle of attack of the runway Greater than the critical angle of attack The time was determined to be an abnormality of low speed takeoff.
[0085] When an abnormality of low-speed takeoff is detected, the following cascading sequence of control correction commands is generated sequentially: Stabilize the control stick to control the angle of attack: Output a command to keep the current control stick position unchanged, locking the angle of attack to prevent further divergence; Forward control stick to reduce angle of attack and restore lift-to-drag ratio: Output a quantitative command to push the control stick forward, reducing the angle of attack and bringing the lift coefficient back to a favorable lift coefficient. Nearby, suppressing the downward trend; Hand-foot coordinated anti-stick and anti-rudder to eliminate tilt: When lateral tilt is detected, a hand-foot coordinated anti-stick and anti-rudder command is output in the opposite direction of the aileron and the opposite direction of the rudder. The algorithm penalty factor for the reduction of aileron effectiveness at high angle of attack is taken into account to correct the lateral imbalance. Triggering the landing and touchdown re-acceleration process: When it is determined that the airflow separation has caused the sinking to be uncontrollable, the system outputs a command to abort takeoff, land and touch down, and re-accelerate.
[0086] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0087] Any changes, modifications, substitutions, and variations made to the embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.
Claims
1. A simulation analysis method for aircraft takeoff performance coupled with multiple environmental variables, characterized in that, The method includes: Step S1: Obtain the aircraft's physical parameters and takeoff environment parameters, and construct the simulation dynamics parameter space; Step S2: Based on the simulation dynamic parameters, calculate the true air velocity at takeoff, construct the force balance equation of the aircraft taxiing run, calculate the average equivalent friction coefficient and average acceleration of the taxiing run, and obtain the reference value of the takeoff taxiing run distance; Step S3: Inject multidimensional environmental variable disturbance vectors into the aircraft taxiing force balance equation, resolve the aircraft taxiing force balance equation based on the multidimensional environmental variable disturbance vectors, obtain the disturbed takeoff taxiing distance, recalculate through control variable iteration, and output the relative change of takeoff taxiing distance relative to the takeoff taxiing distance reference value under the action of each environmental variable. Step S4: Based on the true air-to-ground speed, compare the received virtual control speed ratio with the preset front wheel lift timing threshold range, and output the front wheel lift timing compliance judgment result; when the front wheel lift timing is determined to be non-compliant, output the corresponding aerodynamic penalty amount; when the front wheel lift timing is determined to be compliant, compare the skid lift coefficient with the favorable lift coefficient, and output the skid attitude evaluation result. Step S5: Calculate the sideslip angle and angle of attack under crosswind conditions in real time to determine the abnormal takeoff result of the aircraft; Step S6: Output the analysis results, which include relative changes, taxiing attitude assessment results, and aircraft takeoff anomaly results.
2. The method according to claim 1, characterized in that, In step S1, the physical parameters include aircraft weight, engine thrust, wing area, and the maximum lift coefficient corresponding to the angle of attack at ground clearance; The takeoff environmental parameters include the ground friction coefficient and air density.
3. The method according to claim 2, characterized in that, In step S2, the true velocity at takeoff is calculated based on the simulated dynamic parameter space, and its expression is: in, This is the true speed off the ground; For the weight of the aircraft; Wing area; air density; This represents the maximum lift coefficient corresponding to the angle of attack at ground clearance.
4. The method according to claim 3, characterized in that, In step S2, the expression for the average equivalent friction coefficient during gliding is: in, The average aerodynamic drag during the gliding run; For ground wheel friction; For the weight of the aircraft; The expression for the frictional force of the ground wheels is: in, The coefficient of friction of the ground; This represents the average lift during the gliding run; The expression for the average aerodynamic drag during the glide is: in, air density; Wing area; Zero-lift drag coefficient; The lift coefficient during the gliding run; Oswald efficiency factor; The aspect ratio of the wing; The average speed during the gliding run is taken as the true speed at takeoff. One-half; The expression for the average acceleration during gliding is: in, This refers to the average acceleration during the gliding run; It is the acceleration due to gravity; For engine thrust; The expression for the takeoff roll distance reference value is: in, This is the baseline value for takeoff run distance; This is the true speed off the ground; This represents the average acceleration during the gliding run.
5. The method according to claim 4, characterized in that, In step S3, the multidimensional environmental variable disturbance vector includes: engine thrust change, aircraft load change, air density attenuation, headwind speed vector, and runway downhill angle. A multi-dimensional environmental variable disturbance vector is injected into the aircraft's takeoff run force balance equation. Based on the multi-dimensional environmental variable disturbance vector, the aircraft's takeoff run force balance equation is resolved to obtain the disturbed takeoff run distance. Specifically, this includes: When the air density decay is injected, the true air speed is recalculated according to the expression for the true air speed, and the average aerodynamic drag of the runway is updated to obtain the takeoff runway distance after the air density decay disturbance. When injecting the downhill angle of the runway At that time, the gravitational component introduced by the runway downhill slope is converted into an equivalent thrust increment, and the takeoff distance after the downhill angle disturbance is obtained by resolving the expression based on the modified average acceleration expression. The expression is as follows: in, This is the corrected average acceleration during the gliding run; It is the acceleration due to gravity; For engine thrust; The average equivalent friction coefficient during gliding; This is the equivalent thrust increment; For the weight of the aircraft; The angle of the runway downhill; When the headwind speed vector is injected, the takeoff distance after headwind disturbance is obtained by resolving the problem based on the headwind-corrected ground speed; the expression for the headwind-corrected ground speed is: in, This is the ground speed after headwind correction; This is the true speed off the ground; Headwind speed; The expression for the takeoff distance after coupling headwind is: in, This refers to the takeoff run distance after coupling with the headwind; This refers to the average acceleration during the gliding run; This is the true speed off the ground; This refers to the headwind speed.
6. The method according to claim 5, characterized in that, In step S3, the control variables are iteratively recalculated to output the relative change of the takeoff run distance relative to the baseline takeoff run distance under the influence of each environmental variable, specifically including: Using a controlled variable iterative approach, each time all parameters except the current environmental variable are kept constant, only the current environmental variable or its preset combination are changed, and the corresponding takeoff distance after disturbance is re-solved. The takeoff distance after each disturbance is compared with the baseline takeoff distance to calculate the relative change, which is expressed as follows: in, It is a relative change. This refers to the takeoff distance after the disturbance. This is the baseline value for takeoff run distance.
7. The method according to claim 5, characterized in that, In step S4, the expression for the virtual manipulation speed ratio is: in, The percentage of virtual manipulation speed; The airspeed at which the pilot performs the nose wheel lift maneuver; This is the true speed off the ground; When the proportion of virtual control speed is less than the lower limit of the preset front wheel lift timing threshold range, it is determined to be premature front wheel lift; when the proportion of virtual control speed is greater than the upper limit of the preset front wheel lift timing threshold range, it is determined to be late front wheel lift; when the proportion of virtual control speed is greater than or equal to the lower limit of the preset front wheel lift timing threshold range and less than or equal to the upper limit of the preset front wheel lift timing threshold range, it is determined to be compliant with the front wheel lift timing. The expression for the pneumatic penalty is: in, air density; Current flight speed; Wing area; This is the current lift coefficient; Oswald efficiency factor; The aspect ratio of the wing; The favorable lift coefficient is calculated using the following expression: in, To achieve a favorable lift coefficient; It is the induced resistance factor; is the coefficient of friction of the ground.
8. The method according to claim 7, characterized in that, In step S4, when the timing of lifting the front wheels is deemed compliant, the gliding lift coefficient is compared with the favorable lift coefficient, and the gliding attitude evaluation result is output, specifically including: Extract the real-time lift coefficient of the aircraft during the current taxiing state. The real-time lift coefficient With favorable lift coefficient The attitude deviation rate was calculated through comparison, and its expression is as follows: in, This refers to the attitude deviation rate. This represents the real-time lift coefficient during the current taxiing phase. To achieve a favorable lift coefficient; According to the attitude deviation rate The relationship between the gliding attitude and the preset deviation threshold range is used to output the gliding attitude evaluation results: If the judgment If the optimal posture is achieved, the optimal evaluation result will be output. If the judgment and If the output is too large, the evaluation result will be too large. If the judgment If the output is too small, the evaluation result will be too small.
9. The method according to claim 8, characterized in that, In step S5, the sideslip angle and angle of attack under crosswind conditions are calculated in real time to determine abnormal takeoff results, including: The sideslip angle is calculated using the following expression: in, This represents the vertical component of the crosswind; This represents the average speed during the gliding run; Crosswind speed; The crosswind angle; The sideslip angle Compared with the preset sideslip angle alarm threshold Compare; if determined If so, the result of the judgment on the crosswind deflection anomaly will be output; After the aircraft takes off, the lateral friction of the wheels disappears, and the steady-state yaw angle is recalculated. Its expression is: in, To stabilize the deflection angle; The stable deflection angle With the sideslip angle alarm threshold Compare; if determined Then the result of the crosswind deflection anomaly judgment will be output.
10. The method according to claim 9, characterized in that, Step S5, which involves real-time calculation of the sideslip angle and angle of attack under crosswind conditions to determine abnormal takeoff results, also includes: The critical angle of attack is calculated, and its expression is as follows: in, This is the critical angle of attack; This represents the maximum lift coefficient corresponding to the ground-flying angle of attack. The lift coefficient during the gliding run; The slope of the lift line; When the detected angle of attack of the runway Greater than the critical angle of attack The time was determined to be an abnormality of low speed takeoff.