A fast estimation method for the longitudinal center of gravity of a tiltrotor aircraft

Abstract

The present invention provides a method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft, which belongs to the field of dynamic modeling and flight test. The method first measures the key distance parameters of the aircraft and the weight borne by the front and rear landing gears when all nacelles are placed in different vertical and horizontal states, and then calculates the proportion of the longitudinal center of gravity position of the aircraft relative to the chord length of the wing based on the moment balance principle, and obtains the forward displacement of the longitudinal center of gravity of the aircraft when each nacelle is placed in a horizontal state relative to a vertical state. Finally, combined with the influence of the nacelle tilt on the center of gravity, the longitudinal center of gravity position of the aircraft when all nacelles of the tilt-rotor aircraft are in any combination of tilt angles is obtained. Compared with the method of direct measurement under all combinations of nacelle tilt angles, the present invention has the advantages of simple and fast realization and accurate fitting of the change law, and can quickly and accurately obtain the longitudinal center of gravity position of the tilt-rotor aircraft during the full envelope flight process, providing support for the analysis of the aircraft's hovering control ability, cruise static stability, etc.

Description

Technical Field

[0001] The invention belongs to the field of dynamic modeling and flight testing, and relates to a method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft. Background Art

[0002] Tilt-rotor aircraft change the direction of propeller thrust by tilting the nacelle in the vertical and horizontal positions, achieving vertical take-off and landing and high-speed level flight mode conversion, thus taking into account the advantages of conventional helicopters and fixed-wing aircraft, and has broad application prospects. At present, tilt-rotor aircraft have developed different configurations such as single nacelle tilt, double nacelle tilt, and triple nacelle tilt. In flight experiments, due to different control strategies, all nacelles of the tilt-rotor aircraft may not be at the same tilt angle, which makes the longitudinal center of gravity of the aircraft vary widely. How to accurately estimate the longitudinal center of gravity of the aircraft under different combinations of nacelle tilt angles is of great significance to the aircraft's controllability and static stability margin analysis.

[0003] The tethering method and weighing method are important methods for measuring the center of gravity of conventional aircraft, but the center of gravity of conventional aircraft is generally fixed and will not move due to changes in configuration during flight. Compared with the lateral direction, the tilting of multiple nacelles of tilt-rotor aircraft poses a great challenge to the measurement of the longitudinal center of gravity in full envelope flight. If tethering or weighing measurements are carried out at each nacelle tilt angle combination, the workload will increase exponentially, which is intolerable in the work of adjusting the weight of flight experiments. Therefore, it is necessary to develop a fast and accurate method for estimating the longitudinal center of gravity of tilt-rotor aircraft in the full envelope flight process. Summary of the invention

[0004] The present invention provides a method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft, so as to solve the problem in the related art that the tilting of multiple nacelles of the tilt-rotor aircraft brings great difficulties to the measurement of the longitudinal center of gravity in full envelope flight, and if tethering or weighing measurement is carried out under each nacelle tilt angle combination, the workload will increase exponentially, seriously affecting the work such as the weight adjustment of the flight experiment, etc.

[0005] A first aspect of the present invention provides a method for quickly estimating the longitudinal center of gravity of a tilt-rotor aircraft, comprising the following steps:

[0006] S1: Measure the distance L from the front landing gear of the tilt-rotor aircraft to the rear landing gear along the fuselage direction fg-rg , the distance from the nose to the front landing gear along the fuselage direction L nose-fg , the distance from the nose to the leading edge of the wing along the direction of the fuselage is L nose-wingle , the average aerodynamic chord length of the wing

[0007] S2: Assuming that the tilt-rotor aircraft has a total of N tiltable nacelles, perform the following steps for all the tiltable nacelles of the tilt-rotor aircraft in the direction from the nose to the tail: Place the kth nacelle in a vertical state and measure the aircraft weight borne by the front landing gear and the weight of the aircraft supported by the rear landing gear Then place the kth nacelle in a horizontal state and measure the aircraft weight borne by the front landing gear. and the weight of the aircraft supported by the rear landing gear Where k = 1, ..., N; when performing the above measurement on the kth nacelle, the other nacelles are placed in a vertical state;

[0008] S3: Calculate the distance from the front landing gear to the center of gravity along the fuselage direction when the kth nacelle is placed in the vertical state using formula (1). The distance from the front landing gear to the center of gravity along the fuselage when the kth nacelle is in a horizontal state Wherein, formula (1) can be expressed as but not limited to:

[0009]

[0010] Formula (2) is used to obtain the forward displacement of the aircraft longitudinal center of gravity when the kth nacelle turns from a vertical state to a horizontal state: cog (k), wherein formula (2) can be expressed as but not limited to:

[0011]

[0012] S4: Use formula (3) to calculate the distance from the leading edge of the wing to the center of gravity along the fuselage direction when the kth nacelle is placed in the horizontal state Wherein, formula (3) can be expressed as but not limited to:

[0013]

[0014] Formula (4) is used to calculate the proportion of the longitudinal center of gravity position along the wing chord length when the kth nacelle is placed in a horizontal state: Wherein, formula (4) can be expressed as but not limited to:

[0015]

[0016] S5: Formula (5) is used to calculate the proportion λ of the longitudinal center of gravity position of the tilt-rotor aircraft along the chord length direction under any tilt angle vector χ=[χ(1), χ(2), … χ(N)] cog (χ), wherein formula (5) can be expressed as but not limited to:

[0017]

[0018] Among them, χ(k)∈[0°,90°] is the tilt angle of the kth nacelle of the tilt-rotor aircraft, χ(k)=0° means that the kth nacelle is placed in a horizontal state, and χ(k)=90° means that the kth nacelle is placed in a vertical state.

[0019] A second aspect of the present invention provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement a method for rapidly estimating the longitudinal center of gravity position of a tilt-rotor aircraft as described in the above embodiment.

[0020] A third aspect of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method for rapidly estimating the longitudinal center of gravity position of a tilt-rotor aircraft as described above.

[0021] A fourth aspect of the present invention provides a computer program product, comprising a computer program, which, when executed, implements the method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft as described above.

[0022] The embodiment of the present invention can first measure the key distance parameters of the aircraft and the weight borne by the front and rear landing gears when all nacelles are placed in different vertical and horizontal states, and then calculate the proportion of the longitudinal center of gravity position of the aircraft relative to the wing chord length based on the moment balance principle, and obtain the forward displacement of the longitudinal center of gravity of the aircraft when each nacelle is placed in a horizontal state relative to a vertical state. Finally, combined with the influence of the nacelle tilt on the center of gravity, the longitudinal center of gravity position of the aircraft when all nacelles of the tilt-rotor aircraft are in any combination of tilt angles is obtained. Compared with the method of conducting direct measurement under all combinations of tilt angles of the nacelles of the tilt-rotor aircraft, it has the advantages of simple and fast realization and accurate fitting of the change law. Therefore, the problem in the related art that the tilting of multiple nacelles of the tilt-rotor aircraft brings great difficulties to the measurement of the longitudinal center of gravity in the full envelope flight, if the tethering or weighing measurement is carried out under each combination of the tilt angles of the nacelles, it will bring an exponential increase in the workload, seriously affecting the work of the weight adjustment of the flight experiment, etc.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0025] Figure 1 A flowchart of a method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft provided according to an embodiment of the present invention;

[0026] Figure 2 A schematic block diagram of the longitudinal center of gravity position estimation result of a tilt-rotor aircraft at any nacelle tilt angle according to an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0029] The following describes a method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft according to an embodiment of the present invention with reference to the accompanying drawings. In view of the fact that the tilting of multiple nacelles of a tilt-rotor aircraft mentioned in the above background technology brings great difficulties to the measurement of the longitudinal center of gravity in full envelope flight, if tethering or weighing measurement is carried out at each nacelle tilt angle combination, the workload will increase exponentially, seriously affecting the counterweight adjustment of the flight experiment. The present invention provides a method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft. In this method, the key distance parameters of the aircraft and the weight borne by the front and rear landing gears of all nacelles in different vertical and horizontal states can be measured first, and then based on the principle of moment balance, the proportion of the longitudinal center of gravity position of the aircraft relative to the wing chord length is calculated to obtain the forward displacement of the longitudinal center of gravity of the aircraft when each nacelle is placed in a horizontal state relative to a vertical state. Finally, combined with the influence of the nacelle tilt on the center of gravity, the longitudinal center of gravity position of the aircraft of all nacelles of the tilt-rotor aircraft at any tilt angle combination is obtained. Compared with the method of carrying out direct measurement at all nacelle tilt angle combinations of the tilt-rotor aircraft, the method has the advantages of simple and fast realization and accurate fitting of the change law. Thereby, the problem in the related technology that the tilting of multiple nacelles of a tilt-rotor aircraft brings great difficulties to the measurement of the longitudinal center of gravity in full-envelope flight, and if tethering or weighing measurement is carried out at each nacelle tilt angle combination, the workload will increase exponentially, seriously affecting the work such as the weight adjustment of the flight experiment.

[0030] Specifically, Figure 1 The present invention is a flowchart of a method for quickly estimating the longitudinal center of gravity of a tilt-rotor aircraft according to an embodiment of the present invention.

[0031] like Figure 1 As shown, the method for quickly estimating the longitudinal center of gravity position of the tilt-rotor aircraft includes the following steps:

[0032] Taking a single-nacelle tilt-rotor aircraft as an example, the steps for estimating the center of gravity are as follows:

[0033] In step S101, the key distance parameters of the aircraft and the weight borne by the front and rear landing gears when each nacelle is placed in a vertical or horizontal state are measured.

[0034] It can be understood that the embodiment of the present invention can measure the distance L from the front landing gear to the rear landing gear along the fuselage direction. fg-rg =1.58m, the distance from the nose to the front landing gear along the fuselage direction L nose-fg = 1.30m, the distance from the nose to the leading edge of the wing along the direction of the fuselage L nose-wingle =1.26m, average aerodynamic chord length of the wing

[0035] In step S102, the distance from the front landing gear to the center of gravity along the fuselage direction and the forward displacement of the center of gravity of the aircraft are calculated when each nacelle is placed in a vertical or horizontal state.

[0036] It can be understood that the embodiment of the present invention can place the nacelle of the tilt-rotor aircraft in a vertical state and measure the aircraft weight borne by the front landing gear. and the weight of the aircraft supported by the rear landing gear Then put the nacelle in a horizontal state and measure the weight of the aircraft borne by the front landing gear. and the weight of the aircraft supported by the rear landing gear

[0037] Furthermore, the embodiment of the present invention can use formula (6) to calculate the distance from the front landing gear to the center of gravity along the fuselage direction when the nacelle is placed in a vertical state: The distance from the front landing gear to the center of gravity along the fuselage when the nacelle is in a horizontal state Wherein, formula (6) can be expressed as but not limited to:

[0038]

[0039] Furthermore, the embodiment of the present invention can use formula (7) to obtain the forward displacement Δλ of the aircraft center of gravity when the nacelle is turned from a vertical state to a horizontal state: cog (1), wherein formula (7) can be expressed as but not limited to:

[0040]

[0041] In step S103, the proportion of the center of gravity position along the wing chord length direction when each nacelle is placed in a horizontal state is calculated.

[0042] It can be understood that the embodiment of the present invention can use formula (8) to calculate the distance from the leading edge of the wing to the center of gravity along the fuselage direction when the nacelle is placed in a horizontal state: Wherein, formula (8) can be expressed as but not limited to:

[0043]

[0044] Furthermore, the embodiment of the present invention can use formula (9) to calculate the proportion of the longitudinal center of gravity position along the chord length direction of the wing when the nacelle is placed in a horizontal state: Wherein, formula (9) can be expressed as but not limited to:

[0045]

[0046] In step S104, the proportion of the center of gravity position of the tilt-rotor aircraft along the wing chord length direction at any nacelle tilt angle is calculated.

[0047] It can be understood that the embodiment of the present invention can use formula (10) to calculate the proportion λ of the longitudinal center of gravity position of the tilt-rotor aircraft along the wing chord length direction at any nacelle tilt angle: cog (χ), wherein formula (10) can be expressed as but not limited to:

[0048] λ cog (χ)=8.75%·(1-cosχ)+54.82%, (10)

[0049] Among them, χ∈[0°,90°] is the tilt angle of the nacelle of the tilt-rotor aircraft, χ=0° means that the nacelle is placed in a horizontal state, and χ=90° means that the nacelle is placed in a vertical state.

[0050] Based on the above estimation method, the estimation result of the longitudinal center of gravity position of the tilt-rotor aircraft under any nacelle tilt angle obtained in the embodiment of the present invention can be as follows: Figure 2 As shown, from Figure 2 It can be seen that in the embodiment of the present invention, when the nacelle is turned from a vertical state to a horizontal state, the longitudinal center of gravity of the aircraft gradually moves forward, that is, the distance between the center of gravity and the leading edge of the wing is gradually decreasing, and the center of gravity moves forward quickly in the initial stage of the nacelle tilting and moves forward slowly in the later stage, which reflects the important law of the change of the longitudinal center of gravity of the tilt-rotor aircraft.

[0051] According to the method for quickly estimating the longitudinal center of gravity of a tilt-rotor aircraft proposed in an embodiment of the present invention, the key distance parameters of the aircraft and the weight borne by the front and rear landing gears of all nacelles in different vertical and horizontal states can be measured first, and then based on the principle of moment balance, the proportion of the longitudinal center of gravity of the aircraft relative to the chord length of the wing is calculated to obtain the forward displacement of the longitudinal center of gravity of the aircraft when each nacelle is placed in a horizontal state relative to a vertical state. Finally, combined with the influence of the nacelle tilt on the center of gravity, the longitudinal center of gravity of all nacelles of the tilt-rotor aircraft at any tilt angle combination is obtained. Compared with the method of carrying out direct measurement under all nacelle tilt angle combinations of the tilt-rotor aircraft, it has the advantages of simple and fast realization and accurate fitting of the change law. Therefore, the problem that the tilting of multiple nacelles of the tilt-rotor aircraft in the related art brings great difficulties to the measurement of the longitudinal center of gravity in the full envelope flight, and if the tethering or weighing measurement is carried out under each nacelle tilt angle combination, the workload will increase exponentially, seriously affecting the work such as the weight adjustment of the flight experiment, etc.

[0052] Figure 3 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present invention. The electronic device may include:

[0053] A memory 301 , a processor 302 , and a computer program stored in the memory 301 and executable on the processor 302 .

[0054] When the processor 302 executes the program, the method for quickly estimating the longitudinal center of gravity position of the tilt-rotor aircraft provided in the above embodiment is implemented.

[0055] Furthermore, the electronic device further comprises:

[0056] The communication interface 303 is used for communication between the memory 301 and the processor 302 .

[0057] The memory 301 is used to store computer programs that can be run on the processor 302 .

[0058] The memory 301 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0059] If the memory 301, the processor 302 and the communication interface 303 are implemented independently, the communication interface 303, the memory 301 and the processor 302 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 3 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0060] Optionally, in a specific implementation, if the memory 301, the processor 302 and the communication interface 303 are integrated on a chip, the memory 301, the processor 302 and the communication interface 303 can communicate with each other through an internal interface.

[0061] The processor 302 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention.

[0062] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft as described above.

[0063] An embodiment of the present invention further provides a computer program product, including a computer program, which implements the above method for quickly estimating the longitudinal center of gravity position of a tilt-rotor aircraft when the computer program is executed.

[0064] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0065] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0066] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0067] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0068] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0069] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0070] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0071] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for quickly estimating the longitudinal center of gravity of a tilt-rotor aircraft, characterized in that: The following steps are involved: S1: Measure the distance L from the front landing gear of the tilt-rotor aircraft to the rear landing gear along the fuselage direction fg-rg , the distance from the nose to the front landing gear along the fuselage direction L nose-fg , the distance from the nose to the leading edge of the wing along the direction of the fuselage is L nose-wingle , the average aerodynamic chord length of the wing S2: Assuming that the tilt-rotor aircraft has a total of N tiltable nacelles, perform the following steps for all the tiltable nacelles of the tilt-rotor aircraft in the direction from the nose to the tail: Place the kth nacelle in a vertical state and measure the aircraft weight borne by the front landing gear. and the weight of the aircraft supported by the rear landing gear Then place the kth nacelle in a horizontal state and measure the aircraft weight borne by the front landing gear. and the weight of the aircraft supported by the rear landing gear Where k = 1, ..., N; when performing the above measurement on the kth nacelle, the other nacelles are placed in a vertical state; S3: Calculate the distance from the front landing gear to the center of gravity along the fuselage direction when the kth nacelle is placed in the vertical state using formula (1). The distance from the front landing gear to the center of gravity along the fuselage when the kth nacelle is in a horizontal state Wherein, formula (1) is expressed as: Formula (2) is used to obtain the forward displacement of the aircraft longitudinal center of gravity when the kth nacelle turns from a vertical state to a horizontal state: cog (k), where formula (2) is expressed as: S4: Use formula (3) to calculate the distance from the leading edge of the wing to the center of gravity along the fuselage direction when the kth nacelle is placed in the horizontal state Wherein, formula (3) is expressed as: Formula (4) is used to calculate the proportion of the longitudinal center of gravity position along the wing chord length when the kth nacelle is placed in a horizontal state: Wherein, formula (4) is expressed as: S5: Formula (5) is used to calculate the proportion λ of the longitudinal center of gravity position of the tilt-rotor aircraft along the chord length direction under any tilt angle vector χ=[χ(1), χ(2), … χ(N)] cog (χ), where formula (5) is expressed as: Among them, χ(k)∈[0°,90°] is the tilt angle of the kth nacelle of the tilt-rotor aircraft, χ(k)=0° means that the kth nacelle is placed in a horizontal state, and χ(k)=90° means that the kth nacelle is placed in a vertical state.

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