Method and system for acquiring indicated airspeed
By calculating the true angle of attack and lift coefficient on the aircraft, combining normal overload, and calculating the dynamic pressure to obtain the indicated airspeed, the problem of abnormal indicator airspeed when full pressure or static pressure fails, real-time and reliable indicator airspeed acquisition is achieved.
Patent Information
- Application Number
- CN202411842904.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-21
AI Technical Summary
When the full-pressure system or static pressure system on the aircraft is frozen or blocked, it will cause abnormal or failure of the indicated airspeed, which will affect flight safety.
By obtaining the local angle of attack at the current moment, calculate the true angle of attack, and obtain the lift coefficient based on the true angle of attack; at the same time, obtain the lift through normal overload, and then calculate the dynamic pressure, and finally obtain the indicated spacespeed.
It realizes that when full pressure or static pressure fails, the indicated airspeed can be obtained in real time and reliably without adding new equipment, and only software changes are required.
Smart Images
Figure CN119670437A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of atmospheric data acquisition, and in particular, relates to a method and system for acquiring indicated airspeed. Background Art
[0002] Indicated airspeed is the speed value expressed according to the dynamic pressure measured by the aircraft's atmospheric data system and the relationship between flight speed and dynamic pressure under standard atmospheric conditions at sea level. It is generally called indicated airspeed. The value of indicated airspeed represents the size of the aircraft's aerodynamic force and is one of the most important flight data related to flight safety.
[0003] The indicated airspeed on modern aircraft can be directly calculated based on the dynamic pressure. The dynamic pressure is generally obtained by directly solving the total pressure and static pressure collected by the onboard atmospheric data system. However, when the onboard total pressure system or static pressure system has an icing failure or is blocked by foreign objects, it will cause the total pressure or static pressure information to be abnormal or even fail, thereby causing the indicated airspeed to be abnormal or fail. At the same time, it will also cause other data output by the atmospheric data system to deviate seriously from the actual value, affecting flight safety.
[0004] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention
[0005] The purpose of the present application is to provide a method and system for obtaining indicated airspeed to solve at least one problem existing in the prior art.
[0006] The technical solution of this application is:
[0007] A first aspect of the present application provides a method for obtaining an indicated airspeed, comprising:
[0008] In the event of a total pressure failure and / or static pressure failure:
[0009] Obtaining a local angle of attack at a current moment, obtaining a true angle of attack at a current moment according to the local angle of attack, and obtaining a lift coefficient at a current moment according to the true angle of attack;
[0010] Obtaining the normal overload at the current moment, and obtaining the lift at the current moment according to the normal overload;
[0011] Acquire the dynamic pressure at the current moment according to the lift coefficient and the lift;
[0012] The indicated airspeed at the current moment is obtained according to the dynamic pressure.
[0013] In at least one embodiment of the present application, the local angle of attack at the current moment is collected by an angle of attack sensor.
[0014] In at least one embodiment of the present application, obtaining the true angle of attack at the current moment according to the local angle of attack includes:
[0015] α 真 =A*α 局 +B
[0016] Among them, α 真 is the true angle of attack, α 局 is the local angle of attack, A and B are the angle of attack conversion coefficients.
[0017] In at least one embodiment of the present application, the lift coefficient at the current moment is obtained by looking up a table according to the true angle of attack.
[0018] In at least one embodiment of the present application, the normal overload at the current moment is collected by a three-axis accelerometer.
[0019] In at least one embodiment of the present application, obtaining the lift at the current moment according to the normal overload includes:
[0020] L=m*g*n z
[0021] Where L is lift, m is the weight of the aircraft, g is the acceleration due to gravity, and n is the z Normal overload.
[0022] In at least one embodiment of the present application, obtaining the dynamic pressure at the current moment according to the lift coefficient and the lift includes:
[0023] q c =L / (C l *S)
[0024] Among them, q c is the dynamic pressure, C l is the lift coefficient and S is the wing area.
[0025] In at least one embodiment of the present application, obtaining the indicated airspeed at the current moment according to the dynamic pressure includes:
[0026] When Mach number ≤ 1:
[0027]
[0028] When Mach number > 1:
[0029]
[0030] Among them, V i is the indicated airspeed, P n is the standard atmospheric pressure at sea level, c n is the standard speed of sound at sea level, and k is the adiabatic index.
[0031] A second aspect of the present application provides a system for obtaining an indicated airspeed, comprising:
[0032] An angle of attack sensor, used to collect the local angle of attack at the moment of total pressure failure and / or static pressure failure, and transmit it to the air data computer;
[0033] A three-axis accelerometer is used to obtain the normal overload at the moment of full pressure failure and / or static pressure failure and transmit it to the flight tube computer;
[0034] Flight tube computer, used for:
[0035] obtaining the true angle of attack sent by the atmospheric data computer, obtaining the lift coefficient at the current moment according to the true angle of attack, and transmitting the lift coefficient to the atmospheric data computer;
[0036] Obtain the normal overload sent by the triaxial accelerometer, obtain the lift at the current moment according to the normal overload, and transmit the lift to the atmospheric data computer;
[0037] Air Data Computer, used for:
[0038] Obtain the local angle of attack sent by the angle of attack sensor, obtain the true angle of attack at the current moment according to the local angle of attack, and transmit the true angle of attack to the flight tube computer;
[0039] Obtain the lift coefficient and lift sent by the flight tube computer, obtain the dynamic pressure at the current moment based on the lift coefficient and lift, obtain the indicated airspeed at the current moment based on the dynamic pressure, and transmit the indicated airspeed to the relevant systems on board.
[0040] In at least one embodiment of the present application, the flight tube computer transmits the lift coefficient and the lift to the air data computer via a bus.
[0041] In at least one embodiment of the present application, the air data computer transmits the indicated airspeed to related systems on board the aircraft via a bus.
[0042] In at least one embodiment of the present application, the atmospheric data computer obtains the true angle of attack at the current moment according to the local angle of attack, including:
[0043] α 真 =A*α 局 +B
[0044] Among them, α 真 is the true angle of attack, α 局 is the local angle of attack, A and B are the angle of attack conversion coefficients.
[0045] In at least one embodiment of the present application, the flight tube computer looks up a table to obtain the lift coefficient at the current moment according to the true angle of attack.
[0046] In at least one embodiment of the present application, the flight tube computer obtains the lift at the current moment according to the normal overload, including:
[0047] L=m*g*n z
[0048] Where L is lift, m is the weight of the aircraft, g is the acceleration due to gravity, and n is the z Normal overload.
[0049] In at least one embodiment of the present application, the atmospheric data computer obtains the dynamic pressure at the current moment according to the lift coefficient and the lift, including:
[0050] q c =L / (C l *S)
[0051] Among them, q c is the dynamic pressure, C l is the lift coefficient and S is the wing area.
[0052] In at least one embodiment of the present application, the atmospheric data computer obtains the indicated airspeed at the current moment according to the dynamic pressure, including:
[0053] When Mach number ≤ 1:
[0054]
[0055] When Mach number > 1:
[0056]
[0057] Among them, V i is the indicated airspeed, P n is the standard atmospheric pressure at sea level, c n is the standard speed of sound at sea level, and k is the adiabatic index.
[0058] The invention has at least the following beneficial technical effects:
[0059] The method for obtaining the indicated airspeed of the present application has a simple and reliable algorithm, can obtain the indicated airspeed in real time, does not require new equipment on the aircraft, only needs to modify the software, and the modification workload is low. BRIEF DESCRIPTION OF THE DRAWINGS
[0060] Figure 1 is a flow chart of a method for obtaining indicated airspeed according to an embodiment of the present application;
[0061] Figure 2 It is a schematic diagram of an indicated airspeed acquisition system according to an embodiment of the present application. DETAILED DESCRIPTION
[0062] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.
[0063] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.
[0064] When the full pressure system or static pressure system is working normally, the atmospheric data computer receives the total pressure and static pressure of the full and static pressure system, receives the local angle of attack from the angle of attack sensor, and completes the calculation and output of the pressure altitude, indicated airspeed, Mach number and true angle of attack based on the above information. When the full pressure system or static pressure system on the aircraft fails, the dynamic pressure obtained by the atmospheric data computer will be abnormal or invalid, and the output indicated airspeed will also be abnormal or invalid. In response to this situation, the present application provides a method and system for obtaining indicated airspeed.
[0065] The following is combined with Figure 1 to Figure 2 This application is described in further detail.
[0066] The first aspect of the present application provides a method for obtaining an indicated airspeed, comprising the following steps:
[0067] In the event of a total pressure failure and / or static pressure failure:
[0068] Obtain the local angle of attack at the current moment, obtain the true angle of attack at the current moment according to the local angle of attack, and obtain the lift coefficient at the current moment according to the true angle of attack;
[0069] Get the normal overload at the current moment, and get the lift at the current moment according to the normal overload;
[0070] Obtain the dynamic pressure at the current moment according to the lift coefficient and the lift;
[0071] The indicated airspeed at the current moment is obtained based on the dynamic pressure.
[0072] In a preferred embodiment of the present application, the local angle of attack at the current moment is collected by an angle of attack sensor. After obtaining the local angle of attack, the formula for calculating the true angle of attack at the current moment by the local angle of attack is as follows:
[0073] α 真 =A*α 局 +B
[0074] Among them, α 真 is the true angle of attack, α 局 is the local angle of attack, A and B are the angle of attack conversion coefficients. The angle of attack conversion coefficients A and B are related to the Mach number and aircraft configuration, and the specific values are obtained by aerodynamic simulation.
[0075] In this embodiment, after the true angle of attack is obtained, the lift coefficient at the current moment is obtained by looking up a table based on the true angle of attack.
[0076] In a preferred embodiment of the present application, the normal overload at the current moment is collected by a triaxial accelerometer. The formula for calculating the lift at the current moment according to the normal overload is as follows:
[0077] L=m*g*n z
[0078] Where L is lift, m is the weight of the aircraft, g is the acceleration due to gravity, and n is the z Normal overload.
[0079] In this embodiment, after the lift coefficient and the lift are obtained, the dynamic pressure at the current moment is calculated according to the lift coefficient and the lift, and the calculation formula is:
[0080] q c =L / (C l *S)
[0081] Among them, q c is the dynamic pressure, C l is the lift coefficient and S is the wing area.
[0082] The method for obtaining the indicated airspeed of the present application finally obtains the indicated airspeed at the current moment according to the dynamic pressure, including:
[0083] When Mach number ≤ 1:
[0084]
[0085] When Mach number > 1:
[0086]
[0087] Among them, V iis the indicated airspeed, P n is the standard atmospheric pressure at sea level, c n is the standard speed of sound at sea level, and k is the adiabatic index.
[0088] A second aspect of the present application provides an indicated airspeed acquisition system, comprising: an angle of attack sensor, a three-axis accelerometer, a flight tube computer, and an air data computer.
[0089] Specifically, Figure 2 As shown, the angle of attack sensor is used to collect the local angle of attack at the time of total pressure failure and / or static pressure failure, and transmit it to the air data computer. The triaxial accelerometer is used to obtain the normal overload at the time of total pressure failure and / or static pressure failure, and transmit it to the flight tube computer.
[0090] The flight tube computer is used to obtain the true angle of attack sent by the atmospheric data computer, obtain the lift coefficient at the current moment based on the true angle of attack, and transmit the lift coefficient to the atmospheric data computer; it is also used to obtain the normal overload sent by the three-axis accelerometer, obtain the lift at the current moment based on the normal overload, and transmit the lift to the atmospheric data computer.
[0091] The atmospheric data computer is used to obtain the local angle of attack sent by the angle of attack sensor, obtain the true angle of attack at the current moment based on the local angle of attack, and transmit the true angle of attack to the flight tube computer; it is also used to obtain the lift coefficient and lift sent by the flight tube computer, obtain the dynamic pressure at the current moment based on the lift coefficient and lift, obtain the indicated airspeed at the current moment based on the dynamic pressure, and transmit the indicated airspeed to the relevant systems on board.
[0092] In the indicated airspeed acquisition system of the present application, the flight tube computer transmits the lift coefficient and lift to the air data computer via the bus. The air data computer transmits the indicated airspeed to the relevant systems on board via the bus.
[0093] In a preferred embodiment of the present application, the atmospheric data computer obtains the true angle of attack at the current moment according to the local angle of attack, including:
[0094] α 真 =A*α 局 +B
[0095] Among them, α 真 is the true angle of attack, α 局 is the local angle of attack, A and B are the angle of attack conversion coefficients.
[0096] In this embodiment, the flight tube computer looks up a table to obtain the lift coefficient at the current moment according to the true angle of attack.
[0097] In this embodiment, the flight tube computer obtains the lift at the current moment according to the normal overload, including:
[0098] L=m*g*n z
[0099] Where L is lift, m is the weight of the aircraft, g is the acceleration due to gravity, and n is the z Normal overload.
[0100] In this embodiment, the atmospheric data computer obtains the dynamic pressure at the current moment according to the lift coefficient and the lift, including:
[0101] q c =L / (C l *S)
[0102] Among them, q c is the dynamic pressure, C l is the lift coefficient and S is the wing area.
[0103] In this embodiment, the atmospheric data computer obtains the indicated airspeed at the current moment according to the dynamic pressure, including:
[0104] When Mach number ≤ 1:
[0105]
[0106] When Mach number > 1:
[0107]
[0108] Among them, V i is the indicated airspeed, P n is the standard atmospheric pressure at sea level, c n is the standard speed of sound at sea level, and k is the adiabatic index.
[0109] The indicated airspeed acquisition system of this application requires all the equipment already on board, and no new equipment is needed, so the system is simple to implement. 局 , the normal overload n is obtained by a triaxial accelerometer z ; According to α 局 Get alpha 真 ; by α 真 Get the lift coefficient C at the current moment l ; By normal overload n z Get the lift L at the current moment; from the lift L and the lift coefficient C l , get the current dynamic pressure q c ; Finally, the indicated airspeed V at the current moment is obtained from the dynamic pressure i The application method is simple and reliable, and no new equipment is required on the aircraft. Only the software needs to be modified to achieve real-time acquisition of indicated airspeed when the full pressure or static pressure on the aircraft is abnormal or fails.
[0110] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.
Claims
1. A method for obtaining indicated airspeed, characterized in that: include: In the event of a total pressure failure and / or static pressure failure: Obtaining a local angle of attack at a current moment, obtaining a true angle of attack at a current moment according to the local angle of attack, and obtaining a lift coefficient at a current moment according to the true angle of attack; Obtaining the normal overload at the current moment, and obtaining the lift at the current moment according to the normal overload; Acquire the dynamic pressure at the current moment according to the lift coefficient and the lift; The indicated airspeed at the current moment is obtained according to the dynamic pressure.
2. The method for obtaining indicated airspeed according to claim 1, characterized in that: The local angle of attack at the current moment is collected by the angle of attack sensor.
3. The method for obtaining indicated airspeed according to claim 2, characterized in that: Obtaining the true angle of attack at the current moment according to the local angle of attack includes: a 真 =A*a 局 +B Among them, α 真 is the true angle of attack, α 局 is the local angle of attack, A and B are the angle of attack conversion coefficients.
4. The method for obtaining indicated airspeed according to claim 3, characterized in that: According to the true angle of attack, the lift coefficient at the current moment is obtained by looking up the table.
5. The method for obtaining indicated airspeed according to claim 4, characterized in that: The normal overload at the current moment is collected by a three-axis accelerometer.
6. The method for obtaining indicated airspeed according to claim 5, characterized in that: The lift at the current moment is obtained according to the normal overload, including: L=m*g*n z Where L is lift, m is the weight of the aircraft, g is the acceleration due to gravity, and n is the z Normal overload.
7. The method for obtaining indicated airspeed according to claim 6, characterized in that: Obtaining the dynamic pressure at the current moment according to the lift coefficient and the lift, including: q c =L / (C l *S) Among them, q c is the dynamic pressure, C l is the lift coefficient and S is the wing area.
8. The method for obtaining indicated airspeed according to claim 7, characterized in that: Obtaining the indicated airspeed at the current moment according to the dynamic pressure includes: When Mach number ≤ 1: When Mach number > 1: Among them, V i is the indicated airspeed, P n is the standard atmospheric pressure at sea level, c n is the standard speed of sound at sea level, and k is the adiabatic index.
9. A system for obtaining indicated airspeed, characterized in that: include: An angle of attack sensor, used to collect the local angle of attack at the moment of total pressure failure and / or static pressure failure, and transmit it to the air data computer; A three-axis accelerometer is used to obtain the normal overload at the moment of full pressure failure and / or static pressure failure and transmit it to the flight tube computer; Flight tube computer, used for: obtaining the true angle of attack sent by the atmospheric data computer, obtaining the lift coefficient at the current moment according to the true angle of attack, and transmitting the lift coefficient to the atmospheric data computer; Obtain the normal overload sent by the triaxial accelerometer, obtain the lift at the current moment according to the normal overload, and transmit the lift to the atmospheric data computer; Air Data Computer, used for: Obtain the local angle of attack sent by the angle of attack sensor, obtain the true angle of attack at the current moment according to the local angle of attack, and transmit the true angle of attack to the flight tube computer; Obtain the lift coefficient and lift sent by the flight tube computer, obtain the dynamic pressure at the current moment based on the lift coefficient and lift, obtain the indicated airspeed at the current moment based on the dynamic pressure, and transmit the indicated airspeed to the relevant systems on board.
10. The indicated airspeed acquisition system according to claim 9, characterized in that: The flight tube computer transmits the lift coefficient and lift to the air data computer via the bus.
11. The indicated airspeed acquisition system according to claim 10, characterized in that: The air data computer transmits the indicated airspeed to related systems on board via a bus.
12. The indicated airspeed acquisition system according to claim 11, characterized in that: The atmospheric data computer obtains the true angle of attack at the current moment according to the local angle of attack, including: a 真 =A*a 局 +B Among them, α 真 is the true angle of attack, α 局 is the local angle of attack, A and B are the angle of attack conversion coefficients.
13. The indicated airspeed acquisition system according to claim 12, characterized in that: The flight tube computer looks up a table to obtain the lift coefficient at the current moment according to the true angle of attack.
14. The indicated airspeed acquisition system according to claim 13, characterized in that: The flight tube computer obtains the lift at the current moment according to the normal overload, including: L=m*g*n z Where L is lift, m is the weight of the aircraft, g is the acceleration due to gravity, and n is the z Normal overload.
15. The indicated airspeed acquisition system according to claim 14, characterized in that: The atmospheric data computer obtains the dynamic pressure at the current moment according to the lift coefficient and the lift, including: q c =L / (C l *S) Among them, q c is the dynamic pressure, C l is the lift coefficient and S is the wing area.
16. The indicated airspeed acquisition system according to claim 15, characterized in that: The atmospheric data computer obtains the indicated airspeed at the current moment according to the dynamic pressure, including: When Mach number ≤ 1: When Mach number > 1: Among them, V i is the indicated airspeed, P n is the standard atmospheric pressure at sea level, c n is the standard speed of sound at sea level, and k is the adiabatic index.