A device and method for measuring the longitudinal center of gravity of an aircraft

Abstract

The present invention discloses a device and method for measuring the center of gravity of the longitudinal axis of an aircraft. The aircraft is fixed twice on the side of a support plate, and the center of gravity measurement of the longitudinal axis direction of the aircraft is realized by measuring force twice and utilizing the principle of moment balance. There is no need to install multiple sensors, and the operation, observation and data processing are convenient and the cost is low. Two mounting plates with completely identical structures and four support rods with completely identical structures are adopted, and the center of gravity measurement of the longitudinal axis direction of the aircraft is realized without separating the aircraft and the mounting plates or disassembling the combined structure of the measuring device. Although the gravity and the center of gravity distance of the measuring device are introduced during the two moment balance processes, the symmetrical structure formed by the combination of the mounting plate and the support rod offsets the effects of the gravity and the center of gravity distance of the measuring device during the two moment balance processes, and the center of gravity measurement of the longitudinal axis direction of the aircraft is realized without measuring the weight and the center of gravity of the measuring device.

Description

Technical Field

[0001] The invention belongs to the technical field of center of gravity measurement, and in particular relates to a device and method for measuring the center of gravity of an aircraft longitudinal axis. Background Art

[0002] In the process of aircraft development, the center of gravity is a very important technical indicator. For aircraft with a large aspect ratio, the overall structural design can generally ensure that the center of gravity of the aircraft in the horizontal and vertical axes is near the center axis of the aircraft, while the center of gravity of the aircraft in the longitudinal axis needs to be actually measured after the aircraft is assembled, and even the center of gravity position of the longitudinal axis needs to be adjusted through the counterweight structure. Most of the existing center of gravity measurement methods use the principle of multi-point weighing, which requires multiple sensors to be installed at different parts of the object to be measured to measure simultaneously, and the center of gravity can only be calculated after comprehensive processing of the measurement data of multiple sensors. The measurement process is complicated, the cost is high, the amount of measurement data is large, the calculation process is cumbersome, and even a special data processing computer or processor is required. Some existing patents that use the moment balance principle also have shortcomings. When measuring the center of gravity, some ignore the friction torque in the moment balance analysis, resulting in large measurement errors; in order to reduce aerodynamic drag and increase lift, the aircraft is generally asymmetric along the longitudinal axis of the aircraft, and some center of gravity measurement devices and methods are only applicable to symmetrical structures, which cannot meet the center of gravity measurement in the longitudinal axis of the aircraft. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide an aircraft longitudinal axis center of gravity measurement device and measurement method, which uses the moment balance principle, does not require the installation of multiple sensors, is convenient for operation, observation and data processing, has low cost and high measurement accuracy.

[0004] A device for measuring the center of gravity of a projectile comprises a measuring device, a base (1), a bearing (2), a rotating shaft (3), a support plate (4), a balancing body (5) and a pull rope (6); wherein the base (1) is fixed on the ground, the base (1) is connected to the rotating shaft (3) through the bearing (2), the rotation center line of the rotating shaft (3) is parallel to the horizontal plane, the support plate (4) is fixed to the rotating shaft (3), the left side surface of the support plate (4) is used to install the measuring device, the left side surface of the support plate (4) is perpendicular to the upper surface of the support plate (4), the left side surface of the support plate (4) is parallel to the rotation center line of the rotating shaft (3), the balancing body (5) is installed on the right side of the support plate (4), and the balancing body (5) can slide on the right side of the support plate (4); the pull rope (6) is fixed to the support plate (4), and the distance between the fixing point of the pull rope (6) and the upper surface of the support plate (4) is equal to the distance between the rotation center line of the rotating shaft (3) and the upper surface of the support plate (4);

[0005] The measuring device comprises a mounting plate 1 (11), a mounting plate 2 (12) and four supporting rods (13), wherein the mounting plate 1 (11) and the mounting plate 2 (12) are completely identical plate-shaped structural members processed from the same material, and the four supporting rods (13) are completely identical solid rod-shaped structural members processed from the same material; two ends of the four supporting rods (13) are respectively connected to the mounting plate 1 (11) and the mounting plate 2 (12) to form a frame-type axially symmetrical structure, and the symmetry axis is a connecting line of the center surfaces of the mounting plate 1 (11) and the mounting plate 2 (12).

[0006] Preferably, the four support rods (13) are connected to the four corners of the mounting plate 1 (11) and the mounting plate 2 (12), and the four corners have mounting interfaces with the four support rods (13); each support rod (13) has mounting interfaces with the mounting plate 1 (11) and the mounting plate 2 (12) on both sides, and the mounting plate 1 (11), the mounting plate 2 (12) and the four support rods (13) are connected by standard parts.

[0007] Preferably, the central area of ​​the mounting plate 1 (11) and the mounting plate 2 (12) has a mounting interface with the aircraft (9).

[0008] Furthermore, it also includes an electronic dynamometer (7), which is connected to the free end of the pull rope (6).

[0009] Furthermore, it also includes a level (8), which is placed on the right end surface of the support plate (4); the level axis of the level (8) is perpendicular to the rotation center line of the rotating shaft (3), and the level axis of the level (8) is parallel to the upper surface of the support plate (4).

[0010] A method for measuring a projectile center of gravity measuring device comprises the following steps:

[0011] Step 1: Without installing the aircraft (9) and the measuring device, without tightening the pull rope (6) or installing the electronic dynamometer (7), slide the balancing body (5) to the right along the rotation centerline away from the rotating shaft (3) until it is level with the level gauge (8), and lock the balancing body (5);

[0012] Step 2, the distance between the fixed point of the pull rope (6) and the rotation center line of the rotating shaft (3) is recorded as L1, and the distance between the left side surface of the support plate (4) and the rotation center line of the rotating shaft (3) is recorded as L2; ​​first, the aircraft (9) is installed and fixed in the measuring device, and during installation, it is ensured that the rear end surface of the aircraft (9) is in close contact with the inner plate surface of the mounting plate (11); then the measuring device is fixed and installed on the left side surface of the supporting plate (4), and during installation, it is ensured that the outer plate surface of the mounting plate (11) of the measuring device is in close contact with the left side surface of the supporting plate (4), wherein the gravity of the aircraft (9) is G1, the gravity of the measuring device is G2, the distance from the longitudinal axis center of gravity (10) of the aircraft (9) to the inner plate surface of the mounting plate (11) of the measuring device is recorded as A, the distance from the longitudinal axis center of gravity (14) of the measuring device to the inner plate surface of the mounting plate (11) of the measuring device is recorded as B, and the plate surface thickness of the mounting plate (11) of the measuring device is recorded as L3;

[0013] Step 3, apply a pulling force vertically downward along the plumb line through the electronic dynamometer (7) until the level gauge (8) is horizontal, record the reading of the electronic dynamometer (7) at this time, record it as F1, and record the maximum static friction torque of rotation as M;

[0014] Step 4: Based on the moment balance principle, the mechanical balance equation when the level is horizontal is as follows:

[0015] (F1·L1)-G1·(L2+L3+A)-G2·(L2+L3+B)-M=0 (1)

[0016] Step 5, keep the aircraft (9) mounted and fixed on the mounting plate 1 (11) of the measuring device, remove the measuring device from the left side of the support plate (4), flip the symmetry axis of the measuring device 180 degrees, fix the outer side surface of the mounting plate 2 (12) close to the left side of the support plate (4), and then reinstall the measuring device to the left side of the support plate (4); wherein the length of the support rod (13) of the measuring device is recorded as L4, and the thickness of the mounting plate 2 (12) of the measuring device is recorded as L5;

[0017] Step 6: Apply a pulling force vertically downward along the plumb line through the electronic dynamometer (7) until the level gauge (8) is horizontal, and record the reading of the electronic dynamometer (7) at this time, which is recorded as F2. The maximum static friction torque of the rotation at this time is M;

[0018] Step 7: Based on the moment balance principle, the mechanical balance equation when the level is horizontal is as follows:

[0019] (F2·L1)-G1·(L2+L5+L4-A)-G2·(L2+L5+L4-B)-M=0 (2)

[0020] Step 8:

[0021] L3=L5 (3)

[0022] Step 9. Express B as:

[0023] B=0.5·L4 (4)

[0024] Step 10, solve equations (1), (2), (3), and (4) to calculate the distance from the center of gravity (10) of the longitudinal axis of the aircraft (9) to the inner side of the mounting plate (11) of the measuring device:

[0025] A=0.5·L4+0.5·(F1-F2)·L1 / G1.

[0026] The present invention has the following beneficial effects:

[0027] The present invention uses an ingeniously designed measuring device to install and fix the aircraft twice on the side of the support plate, and through two force measurements, the center of gravity measurement of the aircraft in the longitudinal axis direction is achieved by using the moment balance principle. There is no need to install multiple sensors, and the operation, observation and data processing are convenient and the cost is low.

[0028] The present invention takes friction torque into consideration in the torque balance analysis during measurement, and uses an electronic dynamometer to measure the pulling force, thereby effectively improving the measurement accuracy.

[0029] The measuring device cleverly uses two mounting plates with identical structures and four supporting rods with identical structures, and realizes the measurement of the center of gravity in the longitudinal axis direction of the aircraft without separating the aircraft and the mounting plates or disassembling the combined structure of the measuring device. The measuring device cleverly uses two mounting plates with identical structures and four supporting rods with identical structures. Although the gravity and center of gravity distance of the measuring device are introduced during the two moment balancing processes, the symmetrical structure formed by the combination of the mounting plates and the supporting rods offsets the effects of the gravity and center of gravity distance of the measuring device during the two moment balancing processes, and realizes the measurement of the center of gravity in the longitudinal axis direction of the aircraft without measuring the weight and center of gravity of the measuring device.

[0030] The measuring device cleverly uses two mounting plates with exactly the same structure and four support rods with exactly the same structure. During the two moment balancing processes, although the distance of the aircraft's center of gravity increases by the distance between the front and rear end surfaces of the two mounting plates due to the introduction of the measuring device, the mounting plates and the support rods form a symmetrical structure after combination, which offsets the effects of the aircraft's gravity and the distance between the front and rear end surfaces of the two mounting plates. This achieves measurement of the aircraft's center of gravity in the longitudinal axis direction without measuring the distance between the front and rear end surfaces of the two mounting plates of the measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the measurement platform of the present invention.

[0032] Figure 2This is a schematic diagram of the first measurement after the measuring device and the aircraft are installed in the present invention.

[0033] Figure 3 This is a schematic diagram of the second measurement after the measuring device and the aircraft are installed in the present invention.

[0034] Among them, 1-base, 2-bearing, 3-rotating shaft, 4-support plate, 5-balance body, 6-pull rope, 7-electronic dynamometer, 8-level, 9-aircraft, 10-center of gravity of the aircraft in the longitudinal axis direction, 11-mounting plate 1, 12-mounting plate 2, 13-support rod, 14-center of gravity of the measuring device in the longitudinal axis direction. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0036] The present invention provides a high-precision projectile center of gravity measurement method, comprising the following steps:

[0037] Step 0: Build a measurement platform: Figure 1 As shown, the measuring platform includes a base 1, a bearing 2, a rotating shaft 3, a support plate 4, a balancing body 5, a pull rope 6, an electronic dynamometer 7, and a level 8, wherein the base 1 is fixed on the ground, the base 1 is connected to the rotating shaft 3 through the bearing 2, the rotation center line of the rotating shaft 3 is parallel to the horizontal plane, the support plate 4 is fixed to the rotating shaft 3, the left side of the support plate 4 can be installed with a measuring device, the left side of the support plate 4 is perpendicular to the upper surface of the support plate 4, the left side of the support plate 4 is parallel to the rotation center line of the rotating shaft 3, and the left side of the support plate 4 rotates with the rotating shaft 3 The center line distance is recorded as L2, the level 8 and the balance body 5 are installed on the right side of the support plate 4, the level axis of the level 8 is perpendicular to the rotation center line of the shaft 3, the level axis of the level 8 is parallel to the upper surface of the support plate 4, the balance body 5 can slide and lock on the right side of the support plate 4, the pull rope 6 is fixed to the support plate 4, the distance between the fixed point of the pull rope 6 and the upper surface of the support plate 4 is equal to the distance between the rotation center line of the shaft 3 and the upper surface of the support plate 4, the distance between the fixed point of the pull rope 6 and the rotation center line of the shaft 3 is recorded as L1, and the electronic dynamometer 7 is connected to the pull rope 6;

[0038] The present invention provides a device for measuring the longitudinal center of gravity of an aircraft, such as Figure 2 , Figure 3As shown, it includes a mounting plate 11, a mounting plate 2 12, four support rods 13 and connecting standard parts, wherein the mounting plate 11 and the mounting plate 2 12 are completely identical plate-shaped structural parts processed with the same material, and the four support rods 13 are completely identical solid rod-shaped structural parts processed with the same material; the two ends of the four support rods 13 are respectively connected to the mounting plate 1 11 and the mounting plate 2 12 to form a frame-type axisymmetric structure, and the axis of symmetry is the center line of the mounting plate 1 11 and the mounting plate 2 12. The four support rods 13 are connected to the four corners of the mounting plate 1 11 and the mounting plate 2 12, and there are mounting interfaces with the four support rods 13 at the four corners; the central area of ​​the mounting plate 1 11 and the mounting plate 2 12 has a mounting interface with the aircraft 9, and each support rod 13 has a mounting interface with the mounting plate 1 11 and the mounting plate 2 12 on both sides, and the mounting plate 1 11, the mounting plate 2 12 and the four support rods 13 are connected by standard parts.

[0039] Step 1: Do not install the aircraft 9 and the measuring device, do not tighten the pull rope 6 or install the electronic dynamometer 7, slide the balancing body 5 to the right along the direction away from the rotation centerline of the rotating shaft 3 until it is level with the level gauge 8, and lock the balancing body 5;

[0040] Step 2: Figure 2 As shown, the aircraft 9 is first installed and fixed in the measuring device, and during installation, it is ensured that the rear end face of the aircraft 9 is in close contact with the inner plate surface of the mounting plate 11; then the measuring device is fixedly installed on the left side of the support plate 4, and during installation, it is ensured that the outer plate surface of the mounting plate 11 of the measuring device is in close contact with the left side of the support plate 4, wherein the gravity of the aircraft 9 is G1, the gravity of the measuring device is G2, the distance from the longitudinal axis direction center of gravity 10 of the aircraft 9 to the inner plate surface of the mounting plate 11 of the measuring device is recorded as A, the distance from the longitudinal axis direction center of gravity 14 of the measuring device to the inner plate surface of the mounting plate 11 of the measuring device is recorded as B, and the plate surface thickness of the mounting plate 11 of the measuring device is recorded as L3;

[0041] Step 3, apply a pulling force vertically downward along the plumb line through the electronic dynamometer 7 until the level gauge 8 is horizontal, record the reading of the electronic dynamometer 7 at this time, record it as F1, and record the maximum static friction torque of rotation as M;

[0042] Step 4: Based on the moment balance principle, the mechanical balance equation when the level is horizontal is as follows:

[0043] (F1·L1)-G1·(L2+L3+A)-G2·(L2+L3+B)-M=0(1)

[0044] Step 5: Figure 3As shown, the aircraft 9 is mounted and fixed on the mounting plate 11 of the measuring device, the measuring device is removed from the left side of the support plate 4, the symmetry axis of the measuring device is turned 180 degrees, the outer side of the mounting plate 2 12 is fixed close to the left side of the support plate 4, and the measuring device is reinstalled on the left side of the support plate 4. The length of the support rod 13 of the measuring device is recorded as L4, and the thickness of the mounting plate 2 12 of the measuring device is recorded as L5;

[0045] Step 6, apply a pulling force vertically downward along the plumb line through the electronic dynamometer 7 until the level gauge 8 is horizontal, record the reading of the electronic dynamometer 7 at this time, record it as F2, and the maximum static friction torque of the rotation at this time is M;

[0046] Step 7: Based on the moment balance principle, the mechanical balance equation when the level is horizontal is as follows:

[0047] (F2·L1)-G1·(L2+L5+L4-A)-G2·(L2+L5+L4-B)-M=0 (2)

[0048] Step 8: According to the structural characteristics of the aircraft longitudinal axis center of gravity measuring device, it can be seen that the thickness of the mounting plate 11 and the mounting plate 2 12 of the measuring device are equal, that is,

[0049] L3=L5(3)

[0050] Step 9: Since the distances from the center of gravity 14 of the longitudinal axis of the measuring device to the inner side surfaces of the mounting plate 1 11 and the mounting plate 2 12 of the measuring device are equal, both being half the length of the support rod 13 of the measuring device, B is expressed as:

[0051] B=0.5·L4(4)

[0052] Step 10, solve equations (1), (2), (3), and (4) to calculate the distance from the center of gravity 10 of the longitudinal axis of the aircraft 9 to the inner side of the mounting plate 11 of the measuring device:

[0053] A=0.5·L4+0.5·(F1-F2)·L1 / G1.

[0054] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for measuring the center of gravity of a projectile, It is characterized in that The invention comprises a measuring device, a base (1), a bearing (2), a rotating shaft (3), a support plate (4), a balancing body (5) and a pull rope (6); wherein the base (1) is fixed on the ground, the base (1) is connected to the rotating shaft (3) through the bearing (2), the rotation center line of the rotating shaft (3) is parallel to the horizontal plane, the support plate (4) is fixed to the rotating shaft (3), the left side surface of the support plate (4) is used to install the measuring device, the left side surface of the support plate (4) is perpendicular to the upper surface of the support plate (4), the left side surface of the support plate (4) is parallel to the rotation center line of the rotating shaft (3), the balancing body (5) is installed on the right side of the support plate (4), and the balancing body (5) can slide on the right side of the support plate (4); the pull rope (6) is fixed to the support plate (4), and the distance between the fixing point of the pull rope (6) and the upper surface of the support plate (4) is equal to the distance between the rotation center line of the rotating shaft (3) and the upper surface of the support plate (4); The measuring device comprises a mounting plate 1 (11), a mounting plate 2 (12) and four supporting rods (13), wherein the mounting plate 1 (11) and the mounting plate 2 (12) are completely identical plate-shaped structural members processed from the same material, and the four supporting rods (13) are completely identical solid rod-shaped structural members processed from the same material; two ends of the four supporting rods (13) are respectively connected to the mounting plate 1 (11) and the mounting plate 2 (12) to form a frame-type axially symmetrical structure, and the symmetry axis is a connecting line of the center surfaces of the mounting plate 1 (11) and the mounting plate 2 (12).

2. A device for measuring the center of gravity of a projectile as claimed in claim 1, It is characterized in that Four support rods (13) are connected to four corners of the first mounting plate (11) and the second mounting plate (12), and the four corners have mounting interfaces with the four support rods (13); each support rod (13) has mounting interfaces with the first mounting plate (11) and the second mounting plate (12) on both sides, and the first mounting plate (11), the second mounting plate (12) and the four support rods (13) are connected by standard parts.

3. A device for measuring the center of gravity of a projectile as claimed in claim 2, It is characterized in that The central areas of the mounting plate 1 (11) and the mounting plate 2 (12) have mounting interfaces with the aircraft (9).

4. A device for measuring the center of gravity of a projectile as claimed in claim 1, It is characterized in that It also comprises an electronic dynamometer (7), which is connected to the free end of the pull rope (6).

5. A device for measuring the center of gravity of a projectile as claimed in claim 4, It is characterized in that It also includes a level (8), which is placed on the right end surface of the support plate (4); the level axis of the level (8) is perpendicular to the rotation center line of the rotating shaft (3), and the level axis of the level (8) is parallel to the upper surface of the support plate (4).

6. A measurement method based on the device for measuring the center of gravity of a projectile according to claim 5, It is characterized in that The steps include: Step 1: Without installing the aircraft (9) and the measuring device, without tightening the pull rope (6) or installing the electronic dynamometer (7), slide the balancing body (5) to the right along the rotation centerline away from the rotating shaft (3) until it is level with the level gauge (8), and lock the balancing body (5); Step 2, the distance between the fixed point of the pull rope (6) and the rotation center line of the rotating shaft (3) is recorded as L1, and the distance between the left side surface of the support plate (4) and the rotation center line of the rotating shaft (3) is recorded as L2; ​​first, the aircraft (9) is installed and fixed in the measuring device, and during installation, it is ensured that the rear end surface of the aircraft (9) is in close contact with the inner plate surface of the mounting plate (11); then the measuring device is fixed and installed on the left side surface of the supporting plate (4), and during installation, it is ensured that the outer plate surface of the mounting plate (11) of the measuring device is in close contact with the left side surface of the supporting plate (4), wherein the gravity of the aircraft (9) is G1, the gravity of the measuring device is G2, the distance from the longitudinal axis center of gravity (10) of the aircraft (9) to the inner plate surface of the mounting plate (11) of the measuring device is recorded as A, the distance from the longitudinal axis center of gravity (14) of the measuring device to the inner plate surface of the mounting plate (11) of the measuring device is recorded as B, and the plate surface thickness of the mounting plate (11) of the measuring device is recorded as L3; Step 3, apply a pulling force vertically downward along the plumb line through the electronic dynamometer (7) until the level gauge (8) is horizontal, record the reading of the electronic dynamometer (7) at this time, record it as F1, and record the maximum static friction torque of rotation as M; Step 4: Based on the moment balance principle, the mechanical balance equation when the level is horizontal is as follows: (F1·L1)-G1·(L2+L3+A)-G2·(L2+L3+B)-M=0 (1) Step 5, keep the aircraft (9) mounted and fixed on the mounting plate 1 (11) of the measuring device, remove the measuring device from the left side of the support plate (4), flip the symmetry axis of the measuring device 180 degrees, fix the outer side surface of the mounting plate 2 (12) close to the left side of the support plate (4), and then reinstall the measuring device to the left side of the support plate (4); wherein the length of the support rod (13) of the measuring device is recorded as L4, and the thickness of the mounting plate 2 (12) of the measuring device is recorded as L5; Step 6: Apply a pulling force vertically downward along the plumb line through the electronic dynamometer (7) until the level gauge (8) is horizontal, and record the reading of the electronic dynamometer (7) at this time, which is recorded as F2. The maximum static friction torque of the rotation at this time is M; Step 7: Based on the moment balance principle, the mechanical balance equation when the level is horizontal is as follows: (F2·L1)-G1·(L2+L5+L4-A)-G2·(L2+L5+L4-B)-M=0 (2) Step 8: L3=L5 (3) Step 9. Express B as: B=0.5·L4 (4) Step 10, solve equations (1), (2), (3), and (4) to calculate the distance from the center of gravity (10) of the longitudinal axis of the aircraft (9) to the inner side of the mounting plate (11) of the measuring device: A=0.5·L4+0.5·(F1-F2)·L1 / G1.

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