A method of predicting aircraft range and time en route

Abstract

The application provides a method for predicting the flight range and flight time of an airplane, which divides the whole flight process into a series of flight segments connected in a head-to-tail mode through configurable parameters, then independently analyzes the flight state of each flight segment, iteratively calculates the fuel flow data of each flight segment based on the initial state data of the airplane at the beginning of each calculation, and considers the error between the actual fuel flow data measured by the current sensor and the initially calculated fuel flow data in the calculation of the subsequent flight segment, dynamically adjusts the subsequent prediction model by using the mechanism of gradually decreasing error, accurately calculates the flight range and flight time of each flight segment, and finally accumulates the data of each flight segment to provide the prediction of the flight range and flight time of the airplane in different flight stages. The application provides comprehensive technical support and the most timely and accurate information for flight management and performance evaluation.

Description

Technical Field

[0001] This invention belongs to the technical field of aircraft range and flight time prediction, and specifically relates to a method for predicting aircraft range and flight time. Background Technology

[0002] With the booming development of the global aviation industry and the increasing frequency of international aviation activities, the demand for aircraft with longer range and flight time is showing a year-on-year upward trend in both commercial and civil aviation sectors. Range and flight time respectively represent the distance and time an aircraft can continuously fly in the air, and both are important indicators for measuring aircraft performance, especially for aircraft performing long-haul missions or specific operations. Accurate range and flight time prediction helps air traffic management, enables pilots to make more informed flight decisions, provides a scientific basis for flight operations, and is crucial for ensuring flight safety, improving fuel efficiency, and optimizing flight paths and flight scheduling.

[0003] The maximum range and maximum flight time determined during the aircraft design phase are theoretical performance parameters based on ideal conditions. These parameters represent the aircraft's design limits and potential performance, reflecting the optimal state achievable under ideal conditions. However, in actual flight, the range and flight time of a specific aircraft can be affected by multiple factors in the real flight environment, including but not limited to weather conditions, air traffic control requirements, load conditions, and fuel efficiency. Therefore, there are significant differences between these values ​​and the theoretical values. In practical operation, the focus is more on the actual range and flight time, which reflect the current flight status and can be continuously updated as the flight progresses. These values ​​directly reflect the aircraft's actual performance under specific flight conditions and are a key indicator for measuring flight operational efficiency, playing a crucial role in ensuring flight safety and reliability.

[0004] Traditional methods use aircraft performance databases to directly query and interpolate to calculate the aircraft's range and flight time. However, the data is discrete and the interpolation calculation is prone to introducing calculation errors, which has certain limitations in actual flight and makes it difficult to meet the needs of high-precision real-time calculation. Summary of the Invention

[0005] This invention provides a method for predicting aircraft range and flight time, aiming to eliminate computational accuracy errors introduced by data interpolation. Based on a first-principles aircraft model that is calculated in real-time, independent of data interpolation, and whose calculation data is continuously changing, the method uses original aircraft model parameters such as lift, drag, and engine thrust, and calculates the required flight performance data in real-time based on the fundamental equations of flight dynamics for each flight phase. The first-principles model starts directly from established fundamental physical laws, without relying on historical experience models or parameter fitting methods. The calculation process may involve iterative or recursive logic, and its data calculation results are continuously changing. Therefore, compared to interpolation calculations using performance database models, it has a significantly higher computational accuracy advantage.

[0006] This invention provides a method for predicting aircraft range and flight time, comprising: S1. Based on the current flight phase of the aircraft, determine the starting position of the predicted flight distance and flight time, divide the subsequent flight process into multiple flight segments, and obtain the weight of the current flight segment of the aircraft. S2. Based on the weight of the aircraft in the current flight segment, the pressure ratio, temperature ratio, density, and speed corresponding to the aircraft's current altitude, the lift coefficient is calculated iteratively. Then, the drag coefficient is calculated from the aerodynamic model based on the lift coefficient, and the required thrust is calculated from the drag coefficient. The required fuel flow rate data is calculated based on the required thrust, and corrected based on the current measured fuel flow rate. The fuel mileage is obtained based on the correction results, and the flight range and flight time data of the aircraft in the current flight segment are calculated based on the fuel mileage. S3. Based on the flight distance and flight time data of the current flight segment, obtain the weight of the next flight segment of the aircraft, take the next flight segment of the aircraft as the current flight segment of the aircraft, and execute S2 again until all flight segments are traversed to obtain the flight distance and flight time data of all flight segments. S4. Accumulate the flight distance and flight time of each flight segment, and update the flight distance and flight time data according to the current flight phase.

[0007] Optionally, step 2 involves iteratively calculating the lift coefficient, specifically including the following steps: Step 41: Based on the given drag coefficient C D Angle of attack α The lift coefficient is obtained using the following formula: (16) Step 42: Based on the lift coefficient calculated in Step 41 C L Based on the relationship between the lift coefficient, drag coefficient, and angle of attack using the aircraft aerodynamic model, the drag coefficient can be determined. C D Angle of attack αBy repeatedly executing steps 41 and 42 until the lift coefficients calculated in two consecutive iterations reach the required accuracy or exceed the maximum number of iterations, the lift coefficient is obtained. C L The final calculation result.

[0008] Optionally, in step 2, the required thrust is calculated from the drag coefficient, including: The required thrust is calculated using the following formula. F N ; (17).

[0009] Optionally, before calculating the required fuel flow data based on the desired thrust, the method further includes: Based on the aircraft engine model, query the maximum cruise thrust that can be output, and determine that the maximum cruise thrust is greater than the required thrust.

[0010] Optionally, S1 includes the following steps: Step 21: Set different calculation starting positions according to different flight phases, and calculate the total weight of the aircraft and fuel weight at the starting point of the flight distance and flight time; Step 22: Divide the flight process into multiple flight segments using configurable parameters and determine the interval between each flight segment; Step 23: Determine the starting weight of each flight segment, and record the aircraft weight at the starting point of each flight segment as . W i ,in i The value is 0 arrive N-1 Let N be the number of segments, then we have: (1) Step 24: Determine the final weight of each flight segment, and record the aircraft weight at the end of each flight segment as _____. W i+1 Then we have: (2) Step 25: Determine the average weight of the aircraft for the flight segment as follows: (3).

[0011] Optionally, the required fuel flow rate data is calculated based on the desired thrust, and then corrected according to the current measured fuel flow rate, including the following steps: Step 51: Fuel flow data of the engine model FF , for height h ,Mach number M Temperature deviation △ISA and engine thrust Thr The function, n The number of engines is [number], and the thrust is the required thrust. F N / n Then the calculated fuel flow rate is available. FF i for: (19) Step 52: When the current flight phase is the cruise phase, based on the current fuel flow rate... FF c The calculation takes into account the error between the current fuel flow rate and the initially calculated fuel flow rate, and corrects for subsequent flight segments by taking into account weight. W i and distance S i Correction for the initial fuel flow error, where S i Let the distance from the start of the flight segment to the aircraft's current position be denoted as , and to ensure that the correction amount in subsequent flight segments continuously decreases, then the correction error for fuel flow is: (20) This is a correction mechanism that gradually reduces error correction, where the function g(x) Let be the error attenuation coefficient, then we have: (twenty one).

[0012] Optionally, the fuel mileage is obtained based on the correction results, and the flight distance and flight time data of the current flight segment of the aircraft are calculated based on the fuel mileage, including the following steps: Step 61: Based on the current wind speed and direction V W and vacuum speed V Then there is ground speed V Gnd Size: (twenty two) The ground speed is the vector sum of the vacuum speed and the wind speed; Step 62: Based on the calculated ground speed V Gnd Fuel flow FF i and fuel mileage FM i The relationship between these factors leads to the calculation of fuel mileage. FM i for: (twenty three) Step 63: Based on the initial and final weights of the flight segment and the calculated fuel mileage, calculate the range of this flight segment. △R i for: (twenty four) Step 64: Based on the calculated ground speed V Gnd and the calculated flight distance △R i Then the calculated flight time for that flight segment △T i for: (25) Step 65: Update the index i The value; Step 66: Predicted remaining fuel weight F remaining Updated to: (26) Step 67: Based on the predicted remaining fuel weight, determine whether to continue the calculation for the next flight segment or end the calculation.

[0013] Optionally, update the flight range and flight time data based on the current flight phase, including the following steps: When the current flight phase is pre-flight, takeoff, or climb, the real-time calculated range and flight time are updated and corrected as follows: (29) (30); If the current flight phase is cruise, descent, or approach, the real-time calculated range and flight time data will not be updated or corrected. Of which, total voyage R， Total voyage R, d This is the predicted distance from the current location to the TOC point. t This is the predicted flight time from the current location to the TOC point.

[0014] This invention provides a method for predicting aircraft range and flight time, with the following advantages: 1) The invention method is easy to implement in engineering and can quickly and accurately calculate the actual range and flight time of an aircraft with a low computational load. When the method is integrated into the flight management system, only aerodynamic data and engine data from the aircraft performance database and internal input data of the flight management system are required, without relying on other aircraft performance data.

[0015] 2) The invention employs a real-time update mechanism, which can quickly identify and respond to abnormal situations such as changes in the aircraft's flight status and engine failure. Real-time data continuously corrects the prediction model, providing the most timely and accurate future trend prediction information for flight management and performance evaluation. This enables pilots to take necessary preventive measures based on a full understanding of the current flight status, reduce potential risks, and thus significantly improve the safety of the system.

[0016] 3) The method of the present invention is applicable to all flight phases and sets different calculation starting positions for different flight phases, ensuring that the calculations for different flight phases are based on the most accurate initial conditions. The calculation results are corrected according to the different flight phases selected. The calculated range and flight time data are relatively conservative estimates, providing sufficient margin to ensure the fuel required for safety, thereby ensuring the safety and reliability of flight.

[0017] 4) This invention divides the entire flight process into a series of interconnected flight segments through configurable parameters. The number of segments can be flexibly adjusted according to the computational accuracy requirements and computational resources, thereby balancing computational accuracy and computational efficiency.

[0018] 5) The method of this invention introduces a fuel flow correction mechanism, which dynamically corrects subsequent calculated data based on the error between the current sensor measured data and the initial calculated data. The subsequent error correction amount is adjusted by gradually decreasing the error, and the impact of the error weakens with distance and time as the flight progresses. This error correction mechanism significantly improves the rationality and accuracy of range and flight time prediction, has higher calculation precision, and makes the prediction results throughout the flight process closer to the actual flight requirements. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the logic for calculating flight distance and flight time; Figure 2 It is the data interaction logic for flight distance and flight time calculation; Figure 3 It is a force analysis of the aircraft during level flight; Figure 4 It is a graph of the fuel flow error correction mechanism function; Figure 5 It is a calculation of the composite vector of ground speed. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0022] Specifically, such as Figure 1-5 As shown, this invention proposes a method for predicting aircraft range and flight time, the process of which is as follows: Step 1: Initialize the values ​​of the data parameters required for the flight distance and flight time prediction calculation, and determine whether to enter the flight distance and flight time prediction calculation logic; Step 2: Set different calculation start positions for different flight phases, calculate the total weight of the aircraft and fuel weight at the start point of the flight range and flight time prediction, divide the flight process into multiple flight segments through configurable parameters, and determine the initial weight and ending weight of each flight segment, as well as the average weight of each flight segment. Step 3: Calculate the pressure ratio, temperature ratio, and density, as well as the vacuum speed corresponding to the planned flight speed or Mach number given during cruise. Step 4: Calculate the lift coefficient iteratively, then calculate the drag coefficient from the aerodynamic model based on the lift coefficient, and finally calculate the required thrust from the drag coefficient. Step 5: Calculate the required fuel flow rate data, taking into account corrections for the current measured fuel flow rate; Step 6: Calculate the ground speed data and fuel mileage of the flight segment, calculate the flight distance and flight time data of the flight segment based on the fuel mileage, and update the initial and final state data of the predicted flight segment. Step 7: Accumulate the data from each flight segment to calculate the predicted flight distance and flight time, and update the flight distance and flight time data according to the current flight phase.

[0023] This invention presents a real-time calculation method for predicting aircraft range and flight time. This method is applicable to various types of aircraft. It divides the entire flight process into a series of interconnected flight segments using configurable parameters, and then performs independent flight state analysis on each segment. Based on the aircraft's current speed, altitude, and remaining fuel weight, and considering current atmospheric conditions, it analyzes the aircraft's stress state to better reflect reality. Using a first-principles aircraft performance calculation method, iteratively calculates the fuel flow data for each flight segment. The error between the actual fuel flow data measured by current sensors and the initially calculated fuel flow data is incorporated into the calculation of subsequent flight segments. A mechanism of gradually decreasing error is used to dynamically adjust the subsequent prediction model, accurately calculating the range and flight time for each flight segment. Finally, the data from all flight segments are accumulated to accurately reflect the true performance indicators of the entire flight, presenting the predicted range and flight time in a manner closest to the current flight state. This method employs a real-time update mechanism, enabling timely responses to various abnormal situations such as flight conditions and engine performance fluctuations. It continuously updates as the flight progresses, reflecting the actual range and flight time under the current flight status. This provides comprehensive technical support and the most timely and accurate information for flight management and performance evaluation, significantly improving the accuracy and reliability of flight plan formulation, providing a theoretical basis for scientific decision-making, and ensuring the efficiency and safety of flight operations.

[0024] For example, step one includes the following steps: Step 11: Initialize the values ​​of the data parameters required for the start-up flight range and flight time prediction calculation.

[0025] Step 12: Determine whether to enter the prediction calculation logic for flight distance and flight time.

[0026] For example, step two includes the following steps: Step 21: Set different calculation starting positions according to different flight phases, and calculate the total weight of the aircraft and fuel weight at the starting point of the flight distance and flight time.

[0027] Step 22: Determine the interval for dividing each flight segment. The interval is a configurable parameter.

[0028] Step 23: Determine the starting weight for each flight segment. Let the starting weight of the aircraft for each flight segment be denoted as _____. W i , where index i The value is 0 arrive N-1 Then we have: (1) Step 24: Determine the final weight of each flight segment. Record the final weight of the aircraft at the end of each flight segment as... Wi+1 , where index i The value is 0 arrive N-1 Then we have: (2) Step 25: Determine the average weight of the aircraft for the flight segment as follows: (3) For example, step three includes the following steps: Step 31: Calculate the pressure ratio at cruising altitude δ Temperature ratio θ and atmospheric density ρ ,in p 0、 T 0、 ρ 0 represents the pressure, temperature, and density at standard sea level, respectively.

[0029] (4) (5) (6) Step 32: Calculate the planned flight airspeed given during cruise. V C Or it could be the Mach number. M The corresponding vacuum velocity, where the gauge velocity is... V C With Mach number M The conversion formula is as follows: (7) From Mach number M Then directly calculate the vacuum velocity. V ,in a For the speed of sound, a If 0 is the speed of sound at standard sea level, then: (8) For example, step four includes the following steps: Step 41: Assume an initial value for the lift coefficient. The initial value of the lift coefficient is: (16) Step 42: Iteratively calculate the lift coefficient. Repeat the process of recalculating the lift coefficient multiple times until the lift coefficients of two consecutive calculations reach the required accuracy or exceed the maximum number of iterations. The lift coefficient is then obtained. C L The final calculation result.

[0030] Step 43: Calculate the lift coefficient based on Step 42. C LThe drag coefficient is calculated using an aircraft aerodynamic model based on the relationship between the lift coefficient, drag coefficient, and angle of attack. C D Angle of attack α .

[0031] Step 44: Based on the drag coefficient calculated in Step 43, and using the aircraft's state equilibrium equations and the relationship between drag and required thrust, calculate the required thrust. F N .

[0032] (17) Step 45: Using the aircraft engine model, query the maximum cruise thrust that can be output to determine whether the engine can output the required thrust.

[0033] For example, step five includes the following steps: Step 51: Fuel flow data of the engine model FF , for height h ,Mach number M Temperature deviation △ISA and engine thrust Thr The function, n The number of engines is [number], and the thrust is the required thrust. F N / n Then the calculated fuel flow rate is available. FF i for: (19) Step 52: When the current flight phase is the cruise phase, based on the current fuel flow obtained in Step 11... FF c The calculation takes into account the error between the current fuel flow rate and the initially calculated fuel flow rate, and corrects for subsequent flight segments by taking into account weight. W i and distance S i Correction for the initial fuel flow error, where S i Let the distance from the start of the flight segment to the aircraft's current position be denoted as , and to ensure that the correction amount in subsequent flight segments continuously decreases, then the correction error for fuel flow is: (20) This is a correction mechanism that gradually reduces error correction, where the function g(x) Let be the error attenuation coefficient, and g(x) The graph of the function is as follows Figure 4 As shown, we have: (twenty one) For example, step six includes the following steps: Step 61: Based on the current wind speed and direction obtained in Step 11, i.e. V W and the vacuum velocity calculated in step 32 V Where the ground speed is the vector sum of the vacuum speed and the wind speed, then the ground speed is... V Gnd Size: (twenty two) Step 62: Based on the calculated ground speed V Gnd Fuel flow FF i and fuel mileage FM i The relationship between these factors leads to the calculation of fuel mileage. FM i for: (twenty three) Step 63: Based on the initial and final weights of the flight segment and the calculated fuel mileage, calculate the range of this flight segment. △R i for: (twenty four) Step 64: Based on the calculated ground speed V Gnd and the calculated flight distance △R i Then the calculated flight time for that flight segment △T i for: (25) Step 65: Update the index i The value.

[0034] Step 66: Predicted remaining fuel weight F remaining Updated to: (26) Step 67: Based on the predicted remaining fuel weight, determine whether to continue the calculation for the next flight segment or end the calculation.

[0035] For example, step seven includes the following steps: Step 71: Gradually accumulate the flight distance calculation results of each flight segment from beginning to end to obtain the final real-time calculated predicted total flight distance. R : (27) Step 72: Accumulate the flight time calculation results of each flight segment step by step from beginning to end to obtain the final real-time calculated predicted total flight time. T : (28) Step 73: Update and correct the flight range and flight time data according to the current flight phase. If the current flight phase is pre-flight, takeoff, or climb, then... d This is the predicted distance from the current location to the TOC point. t The predicted flight time from the current location to the TOC point is updated and corrected in real time based on the calculated flight distance and flight time. (29) (30) If the current flight phase is cruise, descent, or approach, the real-time calculated range and flight time data will not be updated or corrected.

[0036] like Figure 1 This is the top-level logic flowchart of the present invention for controlling the calculation process of flight distance and flight time prediction, including: Step 1: Initialize the values ​​of the data parameters required for the flight distance and time prediction calculation, and determine whether to enter the flight distance and time prediction calculation logic. The process is as follows: Step 11: Initialize the values ​​of the data parameters required for the start-up flight range and flight time prediction calculation.

[0037] To initiate the range and time prediction calculation function, the values ​​of the required data parameters must be initialized to reflect the aircraft's status at the start of each range and time prediction calculation. The initialized parameters include navigation data: the aircraft's current heading, vacuum speed, outside wind speed / direction, and barometric altitude; external system sensor data: current fuel flow, current remaining fuel, outside static temperature, air-to-ground conditions, etc.; and some interaction data between the flight management system. Figure 2 The interaction logic for calculating range and flight time is presented. Because this calculation method employs a real-time update mechanism, the parameter data obtained during the initialization of the current position state parameters can respond promptly to different flight conditions and abnormal situations such as engine performance fluctuations, enabling real-time calculations driven by cycles.

[0038] Step 12: Determine whether to enter the prediction calculation logic for flight distance and flight time.

[0039] Based on the data obtained in step 11, determine whether to enter the core logic process of flight distance and flight time prediction calculation. If all the data parameters obtained in step 11 are valid, the calculation conditions are met, and the logic process of flight distance and flight time prediction calculation is entered; otherwise, the flight distance and flight time will not be calculated.

[0040] Step Two: Set different calculation starting positions for different flight phases, calculate the total aircraft weight and fuel weight at the starting point of the predicted flight distance and flight time, divide the flight process into multiple flight segments, and determine the initial and final weights of each flight segment, as well as the average weight of each flight segment. The process is as follows: Step 21: Set different calculation starting positions according to different flight phases, and calculate the total weight of the aircraft and fuel weight at the starting point of the flight distance and flight time.

[0041] When the current flight phase is pre-flight, takeoff, or climb, the TOC point (climb peak) calculated by the FMS vertical trajectory prediction function is used as the starting point for calculation, and the total weight and remaining fuel at the predicted TOC point are used as the starting point's weight and fuel data. If the current phase is cruise, the current total aircraft weight and remaining fuel are directly used as the starting point's weight and fuel data. When the current flight phase is descent or approach, the TOD point calculated by the FMS vertical trajectory prediction function is used as the starting point for calculation, and the total weight and remaining fuel at the predicted TOD point are used as the starting point's weight and fuel data. The total aircraft weight is used to determine the starting point for calculating range and flight time. W t and fuel weight F .

[0042] Step 22: Divide the flight process into multiple flight segments using configurable parameters and determine the interval between each flight segment.

[0043] Starting from the initial point of the flight range and flight time prediction, the flight process is divided into multiple flight segments, and the fuel consumption process is progressively subdivided, with fuel weight... F Divided into N Each paragraph is divided into sections. △F For weight intervals, where △F These are configurable parameters for the flight management system, among which N = F / △F Round up; it is important to note that if the weight is not divisible, the weight interval for the last segment is... △F' = F – (N – 1)*△F .

[0044] Step 23: Determine the starting weight for each flight segment.

[0045] Let the weight of the aircraft at the starting point of each flight segment be... W i , where index i The value is 0 arrive N-1 The starting weight of each flight segment W i for: (1) Step 24: Determine the end weight of each flight segment.

[0046] Using fuel consumption as the weight interval, and with the ending weight of one flight segment being the starting weight of the next, assume the aircraft weight decreases to [weight value] at the end of each flight segment. W i+1 Then we have: (2) Step 25: Determine the average weight of each flight segment.

[0047] Based on the starting and ending weights of each flight segment, the average weight of the aircraft for each flight segment is determined as follows: (3) Step 3: Calculate the pressure ratio, temperature ratio, and density at the cruising altitude, as well as the vacuum speed corresponding to the planned flight airspeed or Mach number given during cruising. The calculation process is as follows: Step 31: Calculate the pressure ratio, temperature ratio, and atmospheric density at the cruising altitude.

[0048] For a given cruising altitude h as well as ISA Deviation △ ISA Calculate the pressure ratio at that height. δ Temperature ratio θ and atmospheric density ρ ,in p 0、 T 0、 ρ 0 represents the pressure, temperature, and density at standard sea level, respectively.

[0049] (4) (5) (6) Step 32: Calculate the vacuum speed corresponding to the planned flight airspeed or Mach number given during cruise.

[0050] Calculate the vacuum velocity of the flight segment V The planned flight speed given for cruise can be the indicated airspeed. V C Or it could be the Mach number. M If it is a speedometer V C Then first set the speedometer. V C Convert to Mach number M Then based on the Mach number M Calculate vacuum speed, gauge speed V C With Mach numberM The conversion formula is as follows: (7) If the planned flight speed given for cruise is Mach number M Then directly calculate the vacuum velocity. V ,in a For the speed of sound, a If 0 is the speed of sound at standard sea level, then: (8) Step 4: Calculate the lift coefficient iteratively, then calculate the drag coefficient using the aerodynamic model based on the lift coefficient, and finally calculate the required thrust using the drag coefficient. The process is as follows: Assuming the aircraft subsequently flies at constant altitude and speed, according to Figure 3 Force analysis of the aircraft during level flight yields the following equilibrium equations: (9) (10) in F N For the required thrust, D For resistance, L For lift, W For gravity, α This is the angle of attack. Then, due to lift... L and resistance D The calculation formula is as follows: (11) (12) in ρ air density, S For wing area, V Vacuum speed, C L and C D Let these be the lift coefficient and the drag coefficient, respectively. Then, according to equations (9), (10), (11), and (12), we can obtain: (13) For aircraft performance databases that store aircraft aerodynamic models, the data is stored in a discrete format, providing drag coefficients. C D With lift coefficient C L The data relationship, including the drag coefficient C D Lift coefficient C L ,Mach number M Center of gravity Cgand aircraft configuration Config The function, that is: (14) Furthermore, the aircraft's aerodynamic model data provides the lift coefficient. C L Angle of attack α The relationship, angle of attack α Lift coefficient C L ,Mach number M The function, that is: (15) Step 41: Assume an initial value for the lift coefficient.

[0051] Substituting equations (14) and (15) into equation (13), only the lift coefficient remains. C L The lift coefficient is an unknown quantity, but since equation (13) is an implicit equation, iterative methods can be used to solve for it. C L First, calculate the assumed angle of attack. α If the initial value is 0, then the initial value of the lift coefficient is: (16) Step 42: Iteratively calculate the lift coefficient.

[0052] Based on the lift coefficient assumed by equation (16), the drag coefficient is first calculated using equations (14) and (15). C D Angle of attack α Then, substitute the calculated value into equation (13) to obtain the new lift coefficient. C L The process of recalculating the lift coefficient is repeated multiple times until the lift coefficients of two consecutive calculations reach the required accuracy or exceed the maximum number of iterations. The calculated lift coefficient is then obtained. C L The final calculation result.

[0053] Step 43: Using the aircraft aerodynamic model, calculate the drag coefficient and angle of attack based on the relationship between the lift coefficient, drag coefficient, and angle of attack.

[0054] The lift coefficient calculated in step 52 C L Then, by using equations (14) and (15), the drag coefficient can be calculated. C D Angle of attack α .

[0055] Step 44: Calculate the required thrust based on the aircraft's state equilibrium equations and the relationship between drag and required thrust.

[0056] Based on the drag coefficient calculated in step 43, the total drag during level flight is calculated using equation (12). Then, the required thrust can be calculated using equations (9) and (12). F N .

[0057] (17) Step 45: Using the aircraft engine model, query the maximum cruise thrust that can be output to determine whether the engine can output the required thrust.

[0058] For an aircraft performance database that stores aircraft engine models, including the maximum cruise thrust data of the engine models... Thr , for height h ,Mach number M and temperature deviation △ISA Functions: (18) The maximum cruise thrust can be calculated by querying the maximum cruise thrust, and the maximum cruise thrust that can be output is determined. Thr With required thrust F N The relationship between them; if they exist F N <Thr If the thrust is insufficient to support the flight, the flight status is invalid, and an error message will be provided.

[0059] Step 5: Calculate the required fuel flow rate data, taking into account corrections for the current measured fuel flow rate: Step 51: Calculate the required fuel flow rate based on the aircraft engine model.

[0060] For an aircraft performance database that stores aircraft engine models, the fuel flow data of the engine models... FF , for height h ,Mach number M Temperature deviation △ISA and engine thrust Thr The function, n The number of engines is [number], and the thrust is the required thrust. F N / n Then the calculated fuel flow rate is available. FF i for: (19) Step 52: Calculate the correction error of fuel flow rate based on the fuel flow rate measured by the sensor.

[0061] When the current flight phase is the cruise phase, the current fuel flow rate obtained in step 11 is used as a reference. FF c The calculation takes into account the error between the current fuel flow rate and the initially calculated fuel flow rate, and corrects for subsequent flight segments by taking into account weight. W i and distance S i Correction for the initial fuel flow error, where S i Let the distance from the start of the flight segment to the aircraft's current position be denoted as , and to ensure that the correction amount in subsequent flight segments continuously decreases, then the correction error for fuel flow is: (20) This is a correction mechanism that gradually reduces error correction, where the function g(x) Let be the error attenuation coefficient, and g(x) The graph of the function is as follows Figure 4 As shown, we have: (twenty one) Step Six: Calculate the ground speed data and fuel mileage for the flight segment. Based on the fuel mileage, calculate the flight distance and flight time data for the flight segment, and update the predicted initial and final state data for the flight segment. The process is as follows: Step 61: Calculate the ground speed of the flight segment.

[0062] Based on the current wind speed and direction obtained in step 11, i.e. V W Assuming the aircraft continues flying along the current heading, primarily because the range and flight time calculation functions are updated in real time, subsequent planned flight segments are not considered; only continuous flight along the current heading is taken into account. The vacuum speed is then calculated using step 32. V The ground speed is the vector sum of the vacuum speed and the wind speed. θ The angle between wind speed and heading direction is shown in the diagram for ground speed calculation. Figure 5 As shown, there is a ground velocity. V Gnd Size: (twenty two) Step 62: Calculate the fuel mileage of the flight segment.

[0063] Based on the calculated ground speed V Gnd Fuel flow FF i and fuel mileage FM i The relationship between these factors leads to the calculation of fuel mileage. FM i for: (twenty three) Step 63: Calculate the flight distance of the flight segment.

[0064] The calculated range of the flight segment is determined based on its initial and final weights, as well as the calculated fuel mileage. △R i for: (twenty four) Step 64: Calculate the flight time of the flight segment.

[0065] Based on the calculated ground speed V Gnd and the calculated flight distance △R i Then the calculated flight time for that flight segment △T i for: (25) Step 65: Update the index i The value.

[0066] Step 66: Predicted remaining fuel weight F remaining Updated to: (26) Step 67: Based on the predicted remaining fuel weight, determine whether to continue the calculation for the next flight segment or end the calculation.

[0067] Predicted remaining fuel weight F remaining If the value is greater than zero, return to step 25, recalculate the average weight of the flight segment, and repeat steps three through six to obtain the range of each subsequent flight segment. △R i Flight time △T i Predicted remaining fuel weight F remaining If the value is less than or equal to zero, the flight distance and flight time prediction logic ends, and then proceed to step seven.

[0068] Step 7: Accumulate the data from each flight segment to calculate the predicted flight distance and flight time, and update the flight distance and flight time data according to the current flight phase. The process is as follows: Step 71: Gradually accumulate the flight distance calculation results of each flight segment from beginning to end to obtain the final real-time calculated predicted total flight distance. R : (27) Step 72: Accumulate the flight time calculation results of each flight segment step by step from beginning to end to obtain the final real-time calculated predicted total flight time. T : (28) Step 73: Update and correct the flight range and flight time data according to the current flight phase. If the current flight phase is pre-flight, takeoff, or climb, then... d This is the predicted distance from the current location to the TOC point. t The predicted flight time from the current location to the TOC point is updated and corrected in real time based on the calculated flight distance and flight time. (29) (30) If the current flight phase is cruise, descent, or approach, the real-time calculated range and time data will not be updated or corrected. Range and time calculations will not consider updates or corrections during the descent and approach phases; instead, they will assume the cruise process continues. This is because fuel consumption during the cruise phase is typically significantly higher than during descent and approach. Therefore, the range and time calculated based on the cruise phase are conservative estimates, providing sufficient margin to ensure the fuel required for a safe descent and approach, thereby ensuring flight safety and reliability.

[0069] In summary, this invention proposes a real-time calculation method for predicting aircraft range and flight time. By dividing the entire flight process into a series of interconnected flight segments, and then iteratively calculating the corresponding fuel flow rate for each segment based on first-principles aircraft performance calculation methods, the subsequent prediction model is dynamically adjusted using a mechanism that gradually reduces fuel flow rate errors. This provides predictions of aircraft range and flight time at different flight stages. It offers comprehensive technical support and the most timely and accurate information for flight management and performance evaluation, significantly improving the accuracy and reliability of flight planning, providing a theoretical basis for scientific decision-making, and ensuring efficient and safe flight operations.

[0070] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A method for predicting aircraft range and flight time, characterized in that, include: S1. Based on the current flight phase of the aircraft, determine the starting position of the predicted flight distance and flight time, divide the subsequent flight process into multiple flight segments, and obtain the weight of the current flight segment of the aircraft. S2. Based on the weight of the aircraft in the current flight segment, the pressure ratio, temperature ratio, density, and speed corresponding to the aircraft's current altitude, the lift coefficient is calculated iteratively. Then, the drag coefficient is calculated from the aerodynamic model based on the lift coefficient, and the required thrust is calculated from the drag coefficient. The required fuel flow rate data is calculated based on the required thrust, and corrected based on the current measured fuel flow rate. The fuel mileage is obtained based on the correction results, and the flight range and flight time data of the aircraft in the current flight segment are calculated based on the fuel mileage. S3. Based on the flight distance and flight time data of the current flight segment, obtain the weight of the next flight segment of the aircraft, take the next flight segment of the aircraft as the current flight segment of the aircraft, and execute S2 again until all flight segments are traversed to obtain the flight distance and flight time data of all flight segments. S4. Accumulate the flight distance and flight time of each flight segment, and update the flight distance and flight time data according to the current flight phase.

2. The method for predicting aircraft range and flight time according to claim 1, characterized in that, Step 2 involves iteratively calculating the lift coefficient, specifically including the following steps: Step 41: Based on the given drag coefficient C D Angle of attack α The lift coefficient is obtained using the following formula: (16) Step 42: Based on the lift coefficient calculated in Step 41 C L Based on the relationship between the lift coefficient, drag coefficient, and angle of attack using the aircraft aerodynamic model, the drag coefficient can be determined. C D Angle of attack α By repeatedly executing steps 41 and 42 until the lift coefficients calculated in two consecutive iterations reach the required accuracy or exceed the maximum number of iterations, the lift coefficient is obtained. C L The final calculation result.

3. The method for predicting aircraft range and flight time according to claim 1, characterized in that, In step 2, the required thrust is calculated from the drag coefficient, including: The required thrust is calculated using the following formula. F N ; (17)。 4. The method for predicting aircraft range and flight time according to claim 1, characterized in that, Before calculating the required fuel flow data based on the desired thrust, the method further includes: Based on the aircraft engine model, query the maximum cruise thrust that can be output, and determine that the maximum cruise thrust is greater than the required thrust.

5. The method for predicting aircraft range and flight time according to claim 1, characterized in that, S1 includes the following steps: Step 21: Set different calculation starting positions according to different flight phases, and calculate the total weight of the aircraft and fuel weight at the starting point of the flight distance and flight time; Step 22: Divide the flight process into multiple flight segments using configurable parameters and determine the interval between each flight segment; Step 23: Determine the starting weight of each flight segment, and record the aircraft weight at the starting point of each flight segment as . W i ,in i The value is 0 arrive N-1 , N Let be the number of segments, then: (1) Step 24: Determine the final weight of each flight segment, and record the aircraft weight at the end of each flight segment as _____. W i+1 Then we have: (2) Step 25: Determine the average weight of the aircraft for the flight segment as follows: (3)。 6. The method for predicting aircraft range and flight time according to claim 1, characterized in that, The required fuel flow rate is calculated based on the desired thrust, and then corrected according to the current measured fuel flow rate. This process includes the following steps: Step 51: Fuel flow data of the engine model FF , for height h ,Mach number M Temperature deviation △ISA and engine thrust Thr The function, n The number of engines is [number], and the thrust is the required thrust. F N / n Then the calculated fuel flow rate is available. FF i for: (19) Step 52: When the current flight phase is the cruise phase, based on the current fuel flow rate... FF c The calculation takes into account the error between the current fuel flow rate and the initially calculated fuel flow rate, and corrects for subsequent flight segments by taking into account weight. W i and distance S i Correction for the initial fuel flow error, where S i Let the distance from the start of the flight segment to the aircraft's current position be denoted as , and to ensure that the correction amount in subsequent flight segments continuously decreases, then the correction error for fuel flow is: (20) This is a correction mechanism that gradually reduces error correction, where the function g(x) Let be the error attenuation coefficient, then we have: (21)。 7. The method for predicting aircraft range and flight time according to claim 6, characterized in that, Based on the corrected results, the fuel mileage is obtained. Then, the flight distance and flight time data for the current flight segment are calculated based on the fuel mileage, including the following steps: Step 61: Based on the current wind speed and direction V W and vacuum speed V Then there is ground speed V Gnd Size: (22) The ground speed is the vector sum of the vacuum speed and the wind speed; Step 62: Based on the calculated ground speed V Gnd Fuel flow FF i and fuel mileage FM i The relationship between these factors leads to the calculation of fuel mileage. FM i for: (23) Step 63: Based on the initial and final weights of the flight segment and the calculated fuel mileage, calculate the range of this flight segment. △R i for: (24) Step 64: Based on the calculated ground speed V Gnd and the calculated flight distance △R i Then the calculated flight time for that flight segment △T i for: (25) Step 65: Update the index i The value; Step 66: Predicted remaining fuel weight F remaining Updated to: (26) Step 67: Based on the predicted remaining fuel weight, determine whether to continue the calculation for the next flight segment or end the calculation.

8. The method for predicting aircraft range and flight time according to claim 1, characterized in that, Updating flight distance and flight time data based on the current flight phase involves the following steps: When the current flight phase is pre-flight, takeoff, or climb, the real-time calculated range and flight time are updated and corrected as follows: (29) (30)； If the current flight phase is cruise, descent, or approach, the real-time calculated range and flight time data will not be updated or corrected. Of which, total voyage R， Total voyage R,d This is the predicted distance from the current location to the TOC point. t This is the predicted flight time from the current location to the TOC point.

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