Aircraft section retrofit method

Abstract

The invention belongs to the technical field of aircraft assembly, and discloses an aircraft section modification method which comprises the following steps: S1, leveling an aircraft; s2, selecting a plurality of horizontal measurement points, and measuring an initial space coordinate value of each horizontal measurement point in a preset space coordinate system; s3, theoretical coordinate values of all the horizontal measurement points are obtained from the aircraft design drawing, and a theoretical full-aircraft coordinate system of the aircraft is obtained through fitting based on a preset space coordinate system, the initial space coordinate values of all the horizontal measurement points and the theoretical coordinate values of all the horizontal measurement points; s4, correcting the theoretical full-aircraft coordinate system according to the self-weight correction coefficient to obtain a standard full-aircraft coordinate system without self-weight influence; s5, the first actual coordinate values of all the horizontal measuring points on the to-be-disassembled section are measured again under the standard full-aircraft coordinate system, and all the horizontal measuring points on the to-be-disassembled section are adjusted to theoretical coordinate values under the standard full-aircraft coordinate system from the first actual coordinate values; and S6, the to-be-disassembled section is separated from the airplane, the to-be-assembled section is installed, and refitting is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft assembly, and in particular to a method for modifying aircraft sections. Background Art

[0002] When conducting certain flight test subjects, it is necessary to modify the fully assembled aircraft for flight test.

[0003] Some flight test projects require modifications to aircraft fuselage sections. Currently, the most common modification method is to directly add components to the aircraft itself, such as installing parachute pods or adding structural reinforcements.

[0004] However, this method makes it difficult to ensure the coordination of the separation surfaces between the newly added structural parts and the original structure, which affects the realization of the structural function, and further affects factors such as the aircraft's attitude and aerodynamic surfaces, making it difficult to ensure the flight performance of the modified aircraft. Summary of the Invention

[0005] The object of the present invention is to provide a method for modifying aircraft sections, thereby ensuring that the aircraft modification complies with the requirements of the aircraft drawing design and that the relative positions, symmetry and postures of the various aircraft components are sufficiently accurate.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The aircraft section modification method comprises the following steps:

[0008] S1. Level the aircraft so that it remains level in both span and heading.

[0009] S2. Select multiple horizontal measurement points on the aircraft and measure the initial spatial coordinate values ​​of each horizontal measurement point in any preset spatial coordinate system;

[0010] S3. Obtain theoretical coordinate values ​​of each horizontal measurement point from the aircraft design drawing, and obtain a theoretical full-aircraft coordinate system of the aircraft by fitting based on a preset spatial coordinate system, the initial spatial coordinate values ​​of each horizontal measurement point, and the theoretical coordinate values ​​of each horizontal measurement point;

[0011] S4. Correcting the theoretical full-aircraft coordinate system using a deadweight correction coefficient to obtain a standard full-aircraft coordinate system without deadweight influence. The deadweight correction coefficient is obtained from the aircraft design data.

[0012] S5. Re-measure the first actual coordinate value of each horizontal measurement point on the section to be disassembled in the standard full-machine coordinate system. Using the theoretical coordinate value in the standard full-machine coordinate system as a reference, adjust each horizontal measurement point on the section to be disassembled from the first actual coordinate value to the theoretical coordinate value in the standard full-machine coordinate system.

[0013] S6. Remove the fasteners used to secure the section to be removed, separate the section to be removed from the aircraft, and install the section to be installed to complete the modification.

[0014] As an optional embodiment of the aircraft section modification method, the horizontal measurement point selected on the fuselage in step S2 is located on the maximum width line and / or the lower zero longitudinal line.

[0015] As an optional embodiment of the aircraft section modification method, the horizontal measurement point selected on the wing in step S2 is located at the intersection of the front beam and the wing rib or the intersection of the rear beam and the wing rib, and is located on the lower wing surface.

[0016] As an optional embodiment of the aircraft section modification method, installing the section to be installed in step S6 includes: selecting multiple horizontal measurement points on the section to be installed, adjusting the posture of the section to be installed in a standard full-aircraft coordinate system so that the horizontal measurement points of the section to be installed are adjusted to theoretical coordinate values, and fastening the section to be installed to the aircraft to complete the modification.

[0017] As an optional embodiment of the aircraft section modification method, step S7 is further included after step S6: coordinate measurement is performed on the horizontal measurement point of the modified aircraft in a standard full-aircraft coordinate system to obtain a second actual coordinate value. If the deviation between the second actual coordinate value and the theoretical coordinate value is less than a preset displacement deviation, the assembly is qualified; otherwise, the posture of the section to be installed is adjusted, and the section to be installed is reinstalled.

[0018] As an optional embodiment of the aircraft segment modification method, the segment to be disassembled includes a segment body and accessory components connected to the segment body;

[0019] After step S4 and before step S5, the accessory component is removed from the segment body;

[0020] In step S5, the first actual coordinate values ​​of each horizontal measurement point on the segment body are remeasured in the standard global coordinate system, and the theoretical coordinate values ​​in the standard global coordinate system are used as a reference to adjust the horizontal measurement points on the segment body from the first actual coordinate values ​​to the theoretical coordinate values ​​in the standard global coordinate system.

[0021] In step S6 , the fasteners used to fix the segment body are removed, the segment body is separated from the aircraft, and the segment to be installed is installed.

[0022] As an optional embodiment of the aircraft section modification method, the main section is the fuselage tail section. In step S5, the fuselage tail section is lifted upward using a lifting mechanism, and each horizontal measurement point on the fuselage tail section is adjusted from a first actual coordinate value to a theoretical coordinate value in a standard full-aircraft coordinate system.

[0023] As an optional embodiment of the aircraft section modification method, the accessory components include one or more of doors, elevators, hydraulic lines, electrical lines, and actuators.

[0024] As an optional embodiment of the aircraft section modification method, step S1 specifically includes: selecting at least two reference points on the fuselage to construct a heading reference line, selecting at least two reference points on the wing to construct a span reference line, and adjusting the heading reference line and the span reference line to remain horizontal.

[0025] As an optional embodiment of the aircraft section modification method, between step S1 and step S2, the method further includes: assembling a modification docking jig on the aircraft to maintain the aircraft's posture.

[0026] Beneficial effects:

[0027] The present invention provides a method for modifying an aircraft section, which levels the aircraft so that the aircraft is kept horizontal in both span and heading. At this time, the actual attitude of the aircraft is formed by the deformation of the attitude designed in the drawing under the influence of its own weight; multiple horizontal measurement points on the aircraft are selected, and the initial spatial coordinate value of each horizontal measurement point is measured in any preset spatial coordinate system, that is, the initial spatial coordinate value under the actual attitude is obtained; the theoretical coordinate value of each horizontal measurement point is obtained from the aircraft design drawing, and based on the preset spatial coordinate system, the initial spatial coordinate value of each horizontal measurement point and the theoretical coordinate value of each horizontal measurement point, the theoretical full-machine coordinate system of the aircraft is obtained by fitting, that is, the theoretical full-machine coordinate system under the influence of its own weight is obtained; and the full-machine coordinate system under the influence of its own weight is modified by its own weight. The positive coefficient corrects the theoretical full-aircraft coordinate system to obtain a standard full-aircraft coordinate system without the influence of deadweight; the first actual coordinate value of each horizontal measurement point on the section to be disassembled is remeasured in the standard full-aircraft coordinate system, and with the theoretical coordinate value in the standard full-aircraft coordinate system as a reference, the horizontal measurement point on the section to be disassembled is adjusted from the first actual coordinate value to the theoretical coordinate value in the standard full-aircraft coordinate system, thereby adjusting the aircraft in the actual posture affected by deadweight to the posture designed in the drawing, and thus replacing the section to be disassembled with the section to be installed in the posture designed in the drawing, thereby ensuring that the aircraft modification meets the requirements of the aircraft drawing design and ensuring that the relative position, symmetry and posture of the various components of the aircraft are sufficiently accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a flow chart of an aircraft section modification method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0030] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0031] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0032] In the description of this embodiment, terms such as "upper," "lower," "right," and "left" are used to refer to positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate description and simplify operation, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meaning.

[0033] like Figure 1 As shown, this embodiment provides a method for modifying an aircraft section. Compared to the prior art method of directly adding structural parts to the aircraft body, this aircraft section modification method replaces the section to be removed with the section to be installed. Specifically, the section to be removed is an aircraft fuselage section without structural parts installed, while the section to be installed is an aircraft fuselage section with structural parts already installed.

[0034] During aircraft section assembly, a laser tracker is typically used in conjunction with ground-based ERS points to establish a global coordinate system. However, after an aircraft is removed from the assembly line, it is no longer on the assembly jig. When modifying an aircraft section, the global coordinate system established during manufacture is difficult to fully align with the aircraft, necessitating a complete reconstruction of the global coordinate system.

[0035] The aircraft section modification method provided in this embodiment specifically includes the following steps:

[0036] S1. Level the aircraft so that it remains horizontal in both span and heading directions. At this point, the actual attitude of the aircraft is formed by the deformation of the attitude designed in the drawing due to the influence of its own weight. Furthermore, step S1 specifically includes: selecting at least two reference points on the fuselage to construct a heading reference line, selecting at least two reference points on the wing to construct a span reference line, and adjusting the heading reference line and the span reference line to remain horizontal.

[0037] S2. Select multiple horizontal measurement points on the aircraft and measure the initial spatial coordinate value of each horizontal measurement point in any preset spatial coordinate system, that is, obtain the initial spatial coordinate value under the actual posture; the number of horizontal measurement points should not be less than 3, for example, such as 6 or 10.

[0038] S3. Obtain theoretical coordinate values ​​of each horizontal measurement point from the aircraft design drawing. Based on the preset spatial coordinate system, the initial spatial coordinate values ​​of each horizontal measurement point, and the theoretical coordinate values ​​of each horizontal measurement point, a theoretical full-aircraft coordinate system of the aircraft is obtained by fitting, i.e., a theoretical full-aircraft coordinate system under the influence of deadweight is obtained.

[0039] S4. Correcting the theoretical full-aircraft coordinate system using a deadweight correction coefficient to obtain a standard full-aircraft coordinate system without deadweight influence. The deadweight correction coefficient is obtained from the aircraft design data.

[0040] S5. Remeasure the first actual coordinate values ​​of each horizontal measurement point on the section to be removed in the standard full-aircraft coordinate system. The measurement equipment used for remeasurement is not limited to any type, such as a laser tracker and a target sphere. Using the theoretical coordinate values ​​in the standard full-aircraft coordinate system as a reference, adjust each horizontal measurement point on the section to be removed from the first actual coordinate values ​​to the theoretical coordinate values ​​in the standard full-aircraft coordinate system. This adjusts the aircraft, which is in its actual posture due to its own weight, to the posture designed in the drawings, eliminating shear forces on the fasteners securing the section to be removed.

[0041] S6. Remove the fasteners securing the section to be removed, detach the section to be removed from the aircraft, and install the section to be installed, completing the modification. In other words, the section to be removed is replaced with the section to be installed, in the design drawing pose. This ensures that the aircraft modification complies with the aircraft design drawings and that the relative positions, symmetry, and poses of the various aircraft components are sufficiently accurate.

[0042] The aircraft section modification method provided in this embodiment eliminates deformations in the aircraft's attitude other than its own weight by leveling the aircraft, ensuring that the aircraft's actual attitude is primarily affected by its own weight. In the actual attitude, a spatial coordinate transformation formula is used to convert a preset spatial coordinate system into a theoretical full-aircraft coordinate system. The deadweight factor in the theoretical full-aircraft coordinate system is then eliminated using a deadweight correction coefficient, thereby establishing a standard full-aircraft coordinate system. Within this standard full-aircraft coordinate system, the position of each aircraft section in the actual attitude can be accurately adjusted, ensuring that the aircraft remains in the design attitude before and after modification. This helps ensure that the aircraft modification complies with the design requirements of the aircraft drawings and ensures sufficient accuracy in the relative position, symmetry, and attitude of the aircraft components.

[0043] In this embodiment, the horizontal measurement points selected on the fuselage in step S2 are located on the maximum width line and / or the lower zero vertical line. Compared to other parts of the fuselage, the fuselage structural rigidity and deformation are greater at the maximum width line and the lower zero vertical line. Positioning the horizontal measurement points on these lines helps improve the accuracy of establishing the theoretical full-aircraft coordinate system. Furthermore, the maximum width line and the lower zero vertical line help ensure measurement accessibility.

[0044] In this embodiment, the horizontal measurement point selected on the wing in step S2 is located at the intersection of the front spar and the rib, or at the intersection of the rear spar and the rib, and is located on the lower wing surface. The intersection of the front spar and the rib or the intersection of the rear spar and the rib has high structural rigidity and low deformation, which is conducive to improving the accuracy of establishing the theoretical full-aircraft coordinate system. The lower wing surface is conducive to ensuring measurement accessibility and facilitating measurement.

[0045] Optionally, the section to be disassembled includes a section body and attached components connected to the section body; after step S4 and before step S5, the attached components are removed from the section body; in step S5, the first actual coordinate values ​​of each horizontal measurement point on the section body are remeasured in the standard global coordinate system, and the theoretical coordinate values ​​in the standard global coordinate system are used as a reference to adjust the horizontal measurement points on the section body from the first actual coordinate values ​​to the theoretical coordinate values ​​in the standard global coordinate system; in step S6, the fasteners securing the section body are removed, the section body is separated from the aircraft, and the section to be installed is installed. Pre-removing the attached components facilitates adjustment of the position of the section body, ensuring that the actual position of the section body corresponds to the theoretical coordinate values ​​and avoiding interference during the adjustment process.

[0046] Of course, when removing accessory components, the actual position of the accessory components can also be adjusted to correspond to the theoretical coordinate values ​​based on the standard global aircraft coordinate system. This can eliminate shear forces in the fasteners between the accessory attachments and the main section, facilitating separation of the accessory components from the main section. In this embodiment, the accessory components include one or more of the following: doors, elevators, hydraulic lines, electrical circuits, and actuators. In this embodiment, the horizontal measurement points on the section to be removed are selected on the horizontal stabilizer, vertical stabilizer, and rudder.

[0047] In this embodiment, the main section is the tail section of the fuselage. In step S5, the tail section is lifted upward using the lifting mechanism, adjusting the horizontal measurement points on the tail section from the first actual coordinate values ​​to the theoretical coordinate values ​​in the standard full-aircraft coordinate system. In other words, the lifting operation provides an upward support force for the tail section, offsetting the influence of its own weight and restoring the tail section to the designed posture on the drawing.

[0048] In this embodiment, between step S1 and step S2, the process further includes: assembling a modified docking frame on the aircraft to maintain the aircraft's posture. The modified docking frame is a prior art, and its specific principle and structure are not described in detail here.

[0049] To ensure the installation of the section on the aircraft in the position indicated in the drawing, step S6 involves selecting multiple horizontal measurement points on the section, adjusting the section's position within the standard aircraft coordinate system, aligning the horizontal measurement points to the theoretical coordinate values, and then securing the section to the aircraft, completing the modification. In this embodiment, after the tail section is installed in this manner, the accessory components are then installed on the section. Furthermore, after the tail section's position is adjusted, connection holes are created on the section's process separation surface, through which fasteners are inserted to secure the section.

[0050] In this embodiment, after step S6, step S7 is further included: coordinate measurement of the horizontal measurement point of the modified aircraft is performed in the standard global aircraft coordinate system to obtain a second actual coordinate value. If the deviation between the second actual coordinate value and the theoretical coordinate value is less than a preset displacement deviation, the assembly is qualified. Otherwise, the posture of the section to be installed is adjusted and the section to be installed is reinstalled. In this embodiment, the preset displacement deviation is the displacement difference between the first actual coordinate value and the theoretical coordinate value.

[0051] In addition to being applicable to the modification of the tail section of an aircraft, the aircraft section modification method provided in this embodiment is also applicable to other sections of an aircraft fuselage, such as the midsection or nose section of an aircraft.

[0052] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for modifying an aircraft section, characterized in that: The following steps are involved: S1. Level the aircraft so that it remains level in both span and heading. S2. Select multiple horizontal measurement points on the aircraft and measure the initial spatial coordinate values ​​of each horizontal measurement point in any preset spatial coordinate system; S3. Obtain theoretical coordinate values ​​of each horizontal measurement point from the aircraft design drawing, and obtain a theoretical full-aircraft coordinate system of the aircraft by fitting based on a preset spatial coordinate system, the initial spatial coordinate values ​​of each horizontal measurement point, and the theoretical coordinate values ​​of each horizontal measurement point; S4. Correcting the theoretical full-aircraft coordinate system using a deadweight correction coefficient to obtain a standard full-aircraft coordinate system without deadweight influence. The deadweight correction coefficient is obtained from the aircraft design data. S5. Re-measure the first actual coordinate value of each horizontal measurement point on the section to be disassembled in the standard full-machine coordinate system. Using the theoretical coordinate value in the standard full-machine coordinate system as a reference, adjust each horizontal measurement point on the section to be disassembled from the first actual coordinate value to the theoretical coordinate value in the standard full-machine coordinate system. S6. Remove the fasteners used to secure the section to be removed, separate the section to be removed from the aircraft, and install the section to be installed to complete the modification.

2. The aircraft section modification method according to claim 1, characterized in that: The horizontal measurement point selected on the fuselage in step S2 is located on the maximum width line and / or the lower zero vertical line.

3. The aircraft section modification method according to claim 1, characterized in that: The horizontal measurement point selected on the wing in step S2 is located at the intersection of the front beam and the wing rib or the intersection of the rear beam and the wing rib, and is located on the lower wing surface.

4. The aircraft section modification method according to claim 1, characterized in that: The installation of the section to be installed in step S6 includes: selecting multiple horizontal measurement points on the section to be installed, adjusting the posture of the section to be installed in the standard full-aircraft coordinate system so that the horizontal measurement points of the section to be installed are adjusted to theoretical coordinate values, and fastening the section to be installed to the aircraft to complete the modification.

5. The aircraft section modification method according to claim 4, characterized in that: After step S6, the method further includes step S7: performing coordinate measurement on the horizontal measurement point of the modified aircraft in a standard full-aircraft coordinate system to obtain a second actual coordinate value. If the deviation between the second actual coordinate value and the theoretical coordinate value is less than a preset displacement deviation, the assembly is qualified; otherwise, the posture of the section to be installed is adjusted, and the section to be installed is reinstalled.

6. The aircraft section modification method according to claim 1, characterized in that: The segment to be disassembled includes a segment body and accessory components connected to the segment body; After step S4 and before step S5, the accessory component is removed from the segment body; In step S5, the first actual coordinate values ​​of each horizontal measurement point on the segment body are remeasured in the standard global coordinate system, and the theoretical coordinate values ​​in the standard global coordinate system are used as a reference to adjust the horizontal measurement points on the segment body from the first actual coordinate values ​​to the theoretical coordinate values ​​in the standard global coordinate system. In step S6 , the fasteners used to fix the segment body are removed, the segment body is separated from the aircraft, and the segment to be installed is installed.

7. The aircraft section modification method according to claim 6, characterized in that: The main section is the fuselage tail section. In step S5, the fuselage tail section is lifted upward by using a lifting mechanism, and each horizontal measurement point on the fuselage tail section is adjusted from the first actual coordinate value to the theoretical coordinate value in the standard full-aircraft coordinate system.

8. The aircraft section modification method according to claim 7, characterized in that: The accessory components include one or more of doors, elevators, hydraulic lines, electrical lines, and actuators.

9. The aircraft section modification method according to claim 1, characterized in that: Step S1 specifically includes: selecting at least two reference points on the fuselage to construct a heading reference line, selecting at least two reference points on the wing to construct a span reference line, and adjusting the heading reference line and the span reference line to keep them both horizontal.

10. The aircraft section modification method according to claim 1, characterized in that: Between step S1 and step S2, the process also includes: assembling a modified docking jig on the aircraft to maintain the aircraft's posture.

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