A counterweight method for large unmanned cargo aircraft flight test performance test

Abstract

The application discloses a counterweight method for large unmanned cargo aircraft test flight performance test, and relates to the field of flight test. The counterweight method for large unmanned cargo aircraft test flight performance test comprises the following steps: obtaining a required torque change amount of movement according to a center of gravity position of an empty aircraft, a required center of gravity adjustment amount and a required installation position of a counterweight; obtaining a required counterweight amount according to the required center of gravity adjustment amount and the required torque change amount of movement; installing a counterweight box to a preset position, and placing corresponding counterweights of the required counterweight amount in the counterweight box, so as to realize center of gravity adjustment in the pitch direction and the roll direction. Through scientific counterweight calculation formula and rigorous method steps, the required counterweight amount of the center of gravity adjustment can be accurately obtained, and the center of gravity adjustment in the pitch direction and the roll direction can be simultaneously considered, so that the problem of insufficient counterweight accuracy caused by the existing water counterweight, sandbag counterweight and the like is effectively solved, and the counterweight accuracy of the large unmanned cargo aircraft is improved.

Description

Technical Field

[0001] This application relates to the field of flight test, and in particular to a counterweight method for flight test performance testing of large unmanned cargo aircraft. Background Technology

[0002] From the development of an aircraft to its test flight, the range of its center of gravity needs to be determined. This is usually achieved by adding counterweights (such as sandbags or lead blocks) inside the aircraft cabin.

[0003] Currently, existing aircraft balancing methods use water ballast, lead weights, and sandbags for center of gravity adjustment. However, these methods have several problems: 1. Water counterweights can achieve multiple center of gravity adjustments, but they are costly and pose a risk of liquid leakage, making them unsuitable for center of gravity adjustments on drones. 2. The main method of fixing lead blocks is to use screw rods. By fixing lead blocks one by one to the screw rods, the center of gravity can be adjusted. However, lead blocks are inconvenient to move and the installation accuracy is insufficient. 3. Sandbag counterweighting involves transporting sandbags one by one onto the plane and then securing them with nets. This method is cumbersome to transport and the securing is not stable enough.

[0004] Therefore, existing counterweight methods, when applied to large unmanned cargo aircraft, suffer from insufficient counterweight accuracy, resulting in significant deviations in flight test performance data. Summary of the Invention

[0005] In view of the deficiencies in the existing technology, the technical problem to be solved by this application is: how to improve the weight accuracy of large unmanned cargo aircraft.

[0006] To achieve the above objectives, the counterweight method for flight performance testing of large unmanned cargo aircraft provided in this application includes the following steps: Based on the empty machine's center of gravity position, the required center of gravity adjustment amount, and the required installation position of the counterweight, the required change in torque for movement is obtained; The required counterweight is obtained based on the required adjustment of the center of gravity and the required change in torque for movement; Install the counterweight box in the preset position and place the corresponding counterweight of the required weight inside the counterweight box to achieve center of gravity adjustment in the pitch and roll directions.

[0007] By adopting the above technical solution, the ballast requirements are accurately obtained through scientific calculation, and the center of gravity is precisely adjusted in the pitch and roll directions. This improves the ballast accuracy of large unmanned cargo aircraft, avoids the cumbersome and error-prone nature of existing ballast methods, and ensures the accuracy of flight test performance data collection, thereby improving the ballast accuracy of large unmanned cargo aircraft.

[0008] In one implementation, the required change in torque for movement is obtained based on the empty machine's center of gravity position, the required center of gravity adjustment amount, and the required installation position of the counterweight, specifically including: The target center of gravity adjustment position is obtained based on the required adjustment amount and the required installation position of the counterweight. Based on the empty aircraft center of gravity position, the target center of gravity adjustment position, and the empty aircraft lever arm, obtain the target lever arm required for adjusting the center of gravity; Based on the target lever arm required to adjust the center of gravity, the change in torque required for the movement is obtained.

[0009] By adopting the above technical solution, the calculation of torque change is further refined. By introducing the concept of target lever arm, the actual offset of the center of gravity can be reflected more accurately, laying a data foundation for subsequent accurate calculation of counterweight and further improving the scientificity and accuracy of center of gravity adjustment.

[0010] In one implementation, obtaining the target lever arm required for adjusting the center of gravity specifically includes: The target lever arm required to adjust the center of gravity is calculated using a first calculation formula, wherein the first calculation formula is: ; Among them, a target The target lever arm required to adjust the center of gravity is defined as follows: %MAC is the percentage of the mean aerodynamic chord, A1 is the target center of gravity adjustment position, A0 is the empty center of gravity position, and a0 is the lever arm when the aircraft is empty, which is the distance between the empty center of gravity and the aircraft coordinate reference plane.

[0011] By adopting the above technical solution, a clear quantitative calculation formula is provided, which can quickly and accurately calculate the force state required for the target center of gravity, reduce the error caused by manual estimation, and improve the efficiency and accuracy of aircraft weight adjustment.

[0012] In one implementation, the required counterweight is obtained based on the required center of gravity adjustment and the required change in torque, specifically including: The required weight is calculated using a second calculation formula, wherein the second calculation formula is: ; Right now ; Where ∆W is the required counterweight, W0 is the empty weight, and a1 is the torque required to install the counterweight box.

[0013] By adopting the above technical solution, the actual required counterweight weight can be calculated intuitively and accurately, ensuring the precise adjustment of the aircraft's center of gravity.

[0014] In one implementation, the adjustment of the center of gravity in the pitch and roll directions specifically includes: The required counterweight is calculated to adjust the center of gravity in the pitch direction. The counterweight box is designed to be installed symmetrically on both sides. The required counterweight is evenly distributed to the left and right sides of the symmetrical counterweight box to adjust the center of gravity in the direction of roll.

[0015] By adopting the above technical solution, the balance of pitch and roll dimensions is taken into account. By symmetrically installing counterweight boxes and evenly distributing the counterweight weight, the lateral balance of the aircraft is ensured while changing the front and rear center of gravity, thus guaranteeing the attitude stability of the large unmanned cargo aircraft during the test flight.

[0016] In one embodiment, the counterweight box includes a box body with a cover plate. When the counterweight box is in a center-of-gravity adjustment state, the cover plate is located on the top of the box body, and the cover plate and the box body form a sealed space. When the counterweight box is in a push-pull usage state, the cover plate is located on the bottom of the box body. Casters are detachably installed on the cover plate.

[0017] By adopting the above technical solution, the counterweight box structure is ingeniously designed. By switching the position of the cover plate and cooperating with the casters, it not only solves the problem of time-consuming and laborious handling in the existing technology, but also serves as a cover plate to ensure that the counterweight does not shake or fall off during test flights. Furthermore, removing the casters during flight effectively reduces irrelevant counterweight and reduces factors that affect the change of the center of gravity.

[0018] In one embodiment, the interior of the box is provided with a partition plate, which divides the sealed space into multiple receiving spaces for placing counterweights; a fixing corner piece is provided between the partition plate and the inner wall of the box.

[0019] By adopting the above technical solutions, the partition plate ensures that the position of the counterweight inside the box will not move due to changes in aircraft attitude and airflow; the corner plates and partition plate work together to make it more secure, achieving precise control of the center of gravity; in addition, unfilled spaces can be filled and fixed with lightweight filler.

[0020] In one embodiment, the bottom of the box is provided with a mounting hole, and a countersunk screw is inserted through the mounting hole; when the counterweight box is in the push-pull mode, the box moves along the freight slide rail; when the counterweight box is in the center of gravity adjustment mode, the box is fixedly connected to the fixed base on the side of the freight slide rail by the countersunk screw.

[0021] By adopting the above technical solution, the existing fixed base of the aircraft cargo system is utilized, eliminating the need to set up extra tethering points in advance, making installation simple and convenient; at the same time, countersunk screws are used to ensure that the bottom of the container is flat, so that the counterweight is placed flat and does not easily shake.

[0022] In one embodiment, the cover plate is provided with a hollow cylinder, and a circular hole is provided on the hollow cylinder. A support column is provided on the rotation shaft of the universal wheel. The support column is telescopic. The rotation shaft is inserted into the hollow cylinder, and the support column is engaged with the circular hole.

[0023] By adopting the above technical solution, the snap-fit ​​structure between the caster and the cover plate is simple and easy to install and remove. When using counterweight, the caster can be quickly pulled out through the spring support, improving operating efficiency.

[0024] In one embodiment, the side of the box is provided with a handle via a reinforcing plate.

[0025] By adopting the above technical solutions, the handle greatly facilitates the operation of the counterweight box when pushing, pulling, placing or moving it. The addition of a reinforcing plate can effectively prevent the handle from falling off during the handling of the box, thus improving the safety of the operation.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. This application, through scientific weight calculation formulas and rigorous methods, can accurately obtain the weight required for center of gravity adjustment, and can simultaneously take into account the center of gravity adjustment in pitch and roll directions. It effectively solves the problem of insufficient weight accuracy caused by existing methods such as water weight and sandbag weight, greatly improves the reliability of flight test performance data acquisition, and thus improves the weight accuracy of large unmanned cargo aircraft. 2. This application designs a counterweight box with switchable usage states. With the cooperation of detachable casters and cover, it greatly facilitates the handling of heavy objects in the push-pull state, saving time and effort. In the center of gravity adjustment test flight state, it serves as a sealed top cover and buckle fixing device, which can effectively reduce unrelated weight and prevent the counterweight from moving when the aircraft is bumpy, thus ensuring precise control of the center of gravity. 3. This application utilizes the existing cargo system and fixed base of large unmanned cargo aircraft for installation and fixation, without the need for additional special tethering points. The installation position is adjustable and highly adaptable. Combined with the internal cross-shaped partition structure fixed by corner pieces, it not only has low manufacturing cost but also a robust structure. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating a counterweight method used for flight performance testing of a large unmanned cargo aircraft, as described in an embodiment of this application. Figure 2 This is a schematic diagram of the structure of the box in an embodiment of this application; Figure 3 This is a schematic diagram of the counterweight box structure in the center-of-gravity adjustment state according to an embodiment of this application; Figure 4 This is a schematic diagram of the counterweight box structure in the push-pull usage state according to an embodiment of this application; Figure 5 This is a schematic diagram of the cover plate structure (with casters installed) according to an embodiment of this application. Figure 6 This is a schematic diagram of the structure of the freight slide rail according to an embodiment of this application; Figure 7 This is a schematic diagram of the cover plate in an embodiment of this application (with the casters removed). Figure 8 This is a schematic diagram of the structure of the universal wheel in an embodiment of this application.

[0028] In the diagram: 1. Box body; 101. Divider plate; 102. Fixing corner piece; 103. Mounting hole; 104. Box body buckle; 105. Reinforcing plate; 106. Handle; 2. Counterweight; 3. Cover plate; 301. Cover plate buckle; 302. Casters; 3021. Rotating shaft; 3022. Support column; 303. Hollow cylinder; 4. Cargo slide rail; 5. Fixed base. Detailed Implementation

[0029] To make the technical objectives, solutions, and beneficial effects of this application clearer, the technical solutions of this application are further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0030] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limiting purposes, so as to provide a thorough understanding of the embodiments of this application. For clarity and brevity, detailed descriptions of systems, devices, circuits, and methods known in the art have been omitted so as not to obscure the description of this application with unnecessary details.

[0031] The main concept of this application is to address the problems of existing sandbag or water-based ballast methods being unable to achieve precise ballast adjustment for large unmanned cargo aircraft, and the inconvenience of transporting traditional ballast boxes. It provides a comprehensive ballast solution that combines a precise torque calculation model with a deformable, reusable ballast box. This solution can achieve precise adjustment of the pitch and roll center of gravity through scientific calculation, and can also be reliably fixed using the aircraft's existing cargo system's fixed base, simplifying the operation process. Example 1

[0032] This embodiment focuses on providing a counterweight method for flight performance testing of large unmanned cargo aircraft, emphasizing its data flow, signal processing, and calculation process.

[0033] In one embodiment, see Figure 1 As shown, the counterweight method for flight performance testing of large unmanned cargo aircraft mainly includes the following steps: Step S1: Based on the empty machine's center of gravity position, the required center of gravity adjustment amount, and the required installation position of the counterweight, obtain the required torque change amount for movement.

[0034] Specifically, the operator or control system first obtains the aircraft's basic parameters. Based on the required center of gravity adjustment amount and the required installation position of the counterweight, the target center of gravity adjustment position is obtained; subsequently, based on the empty center of gravity position, the target center of gravity adjustment position, and the empty lever arm, the target lever arm required for adjusting the center of gravity is calculated.

[0035] The above process involves data processing using the first calculation formula: ; Among them, a target The target lever arm required to adjust the center of gravity; %MAC is the percentage of the mean aerodynamic chord; A1 is the target center of gravity adjustment position; A0 is the empty aircraft center of gravity position; a0 is the lever arm when the aircraft is empty (i.e., the distance between the empty aircraft center of gravity and the aircraft coordinate reference plane).

[0036] By introducing the concept of target lever arm, a clear quantitative calculation model is provided, which can accurately reflect the actual offset of the center of gravity, reduce the error of manual estimation, and lay a data foundation for subsequent accurate calculation of counterweight.

[0037] Step S2: Obtain the required counterweight based on the required center of gravity adjustment and the required change in torque.

[0038] After obtaining the target lever arm, the system calculates the specific weight that needs to be added or reduced using the second calculation formula: ; After mathematical rearrangement and data transformation, the specific expression for the required counterweight is obtained: ; Where ∆W is the required counterweight (i.e., the total change in counterweight), W0 is the empty weight, and a1 is the torque of the counterweight box to be installed (the distance between the position of the counterweight to be installed and the reference plane).

[0039] This step directly maps the center of gravity adjustment target to a specific counterweight physical quantity, making the calculation intuitive and accurate, and avoiding the problems of insufficient or excessive counterweight.

[0040] Step S3: Install the counterweight box to the preset position and place the corresponding counterweight of the required weight into the counterweight box to achieve center of gravity adjustment in the pitch and roll directions.

[0041] To ensure lateral stability, the counterweight boxes are designed to be symmetrically positioned within the aircraft cargo hold. The required counterweight weight ∆W calculated in the previous step is evenly distributed between the two symmetrical counterweight boxes (i.e., the counterweight on one side is ∆W / 2).

[0042] By symmetrically installing and evenly distributing the weight, this technique changes the aircraft's pitch center of gravity (forward and backward movement) while ensuring balance in the roll direction (lateral movement), thus guaranteeing the attitude stability of the large unmanned cargo aircraft during test flights.

[0043] Provide a specific scenario calculation example: To enable those skilled in the art to more clearly implement this method, the following specific parameter scenarios are provided as supporting evidence: Assume a large unmanned cargo aircraft has a center of gravity (MAC) of 2m, an empty center of gravity (A0) of 25% of the MAC, an empty weight (W0) of 7500kg, and a test flight target center of gravity (A1) of 30% of the MAC. The empty arm (a0) is known to be 7m, and the torque (a1) for installing the counterweight box is 8.5m.

[0044] 1) Substitute into the first formula to calculate the target lever arm: a target = 7 + 2 *(30% - 25%) = 7.1m.

[0045] 2) Substitute into the second formula to calculate the total weight: ≈536kg.

[0046] 3) Left-right distribution and structural deduction: Distributing the 536kg evenly, an additional 268kg of counterweight is needed on each side. If the structural weight of a single counterweight box is 18kg, then 250kg of counterweight needs to be added to each box. Preferably, standardized 20kg counterweight blocks can be used, requiring 12 blocks (totaling 240kg). The remaining 10kg difference can be made up using lightweight filler or sandbags of equal volume, ultimately achieving precise adjustment of the aircraft's center of gravity from 25% MAC to 30% MAC. Example 2

[0047] This embodiment focuses on providing a counterweight box structure for performing the above-described counterweight method, and elaborates on the mechanical connection method and relative positional relationship between the components.

[0048] like Figures 2 to 8 As shown, the counterweight box mainly includes a box body 1 and a cover plate 3. The counterweight box can be switched between "push-pull usage mode" and "center of gravity adjustment mode".

[0049] Preferably, the box body 1 is made of a 5mm thick aluminum plate (such as 5052 aluminum) as the bottom and the side walls are made of a 3mm thick aluminum plate welded together, so as to ensure that it can bear a maximum counterweight of no more than 400kg and its overall weight is usually no more than 20kg.

[0050] The box 1 is equipped with partitions 101, which are interlocked or spliced ​​together in a cross pattern to divide the internal space of the box 1 into at least four accommodating cavities. The specific number can be increased or decreased according to needs. The spatial dimensions of the accommodating cavities (e.g., 31×26cm) are perfectly matched to a single counterweight 2 (e.g., with a volume of 30×25×5cm). To increase the connection strength, the partitions 101 are fixed to the inner wall of the box 1 and to each partition 101 using fixing corner pieces 102. The corner pieces are connected by riveting and are arranged in a cross pattern on the left and right sides.

[0051] The cross-shaped and corner-riveting structure not only saves on the overall manufacturing cost of the housing 1, but also makes the internal structure more robust, effectively limiting the amount of play of the counterweight 2 in each cavity, and preventing the center of gravity from shifting dynamically due to changes in the aircraft's attitude or turbulence.

[0052] When the counterweight box is in the center of gravity adjustment state, that is, when it is already fixed in place inside the aircraft: The bottom of the housing 1 has several mounting holes 103, for example, eight. The mounting holes 103 are designed with countersunk screw holes to pass through countersunk screws and to thread the housing 1 directly to the fixed base 5 with a support plate nut on the side of the aircraft cargo slide rail 4.

[0053] By using countersunk screws and countersunk holes, the screw head can be completely inserted into the bottom plate of the box 1, ensuring that the inner surface of the bottom of the box 1 is flat and that the counterweight 2 placed on it will not tilt or shake; at the same time, it can be directly supported by the cargo system base without the need to set up additional mooring points.

[0054] Furthermore, the cover plate 3 is secured to the top of the housing 1 by the housing body buckle 104 and the cover plate buckle 301, forming a closed, sealed space. The casters 302 are removed from the cover plate 3 to reduce unwanted weight interference.

[0055] When the counterweight box is in the push-pull mode, i.e. during the handling process: The cover plate 3 is moved to the bottom of the box 1 and used as a support tray. Casters 302 are detachably installed at the four corners of the cover plate 3.

[0056] A specific mechanical locking structure is provided: a hollow cylinder 303 is fixedly installed on the upper surface of the cover plate 3, and a circular hole is opened on the side wall of the hollow cylinder 303; the rotation shaft 3021 of the caster wheel 302 is embedded with a spring mechanism and connected to a retractable support 3022. During assembly, the rotation shaft 3021 of the caster wheel 302 is aligned and inserted into the hollow cylinder 303. When the spring support 3022 is pressed down and passes over the cylindrical wall, the spring support 3022 pops out under its own elastic force and locks into the circular hole of the hollow cylinder 303, achieving a hard lock; during disassembly, the caster wheel 302 can be easily pulled out by simply pressing the spring support 3022 from the circular hole to release the interference.

[0057] To further facilitate handling, handles 106 are provided around the sides of the box 1, and reinforcing plates 105 are welded to the inner or outer sides of the box wall where the handles 106 are located.

[0058] Through the ingenious switching of the cover plate 3 position and the quick-release spring pin structure, the counterweight box has the dual functions of "a sealed counterweight when stationary" and "a trolley when in motion", which greatly saves manpower for loading and unloading aircraft; the reinforcing plate 105 effectively prevents the handle 106 from falling off under heavy weight, thus improving safety. Example 3

[0059] This embodiment will combine the method of Embodiment 1 and the apparatus of Embodiment 2 to illustrate a complete counterweight operation process: (1) Preparation stage: Connect the four casters 302 to the hollow cylinder 303 of the cover plate 3 through the spring support 3022. After flipping the cover plate 3, place the box 1 on the cover plate 3 to form a push-pull trolley state.

[0060] (2) Weighing and loading stage: The operator calculates the required counterweight weight on one side according to the calculation model mentioned above (such as the 250kg counterweight 2 mentioned above). The corresponding number of counterweights 2 with soft strap handles 106 (20kg each) are stacked into the receiving cavity of the box 1.

[0061] (3) Transportation stage: Hold the handle 106 on the side wall of the box 1, push the counterweight box loaded with counterweight 2 to the rear door of the aircraft, and pull it into the cargo hold of the aircraft along the boarding ramp or rail.

[0062] (4) Fixing and positioning stage: Remove the counterweight 2 from the container 1 and lift the container 1 to detach it from the bottom cover 3. Place the container 1 on the fixed base 5 of the freight system and drive countersunk screws into the mounting holes 103 to rigidly fix the container 1 to the floor.

[0063] (5) Filling and shockproofing stage: Put the counterweight 2 back into the cavity. If there is still an unfilled gap at the top of the cavity, fill it with a lightweight sponge or foam of equal volume to prevent vertical shaking during flight turbulence.

[0064] (6) Locking Stage: Press the spring support 3022 on the caster 302 to pull the four casters 302 off the cover plate 3 and store them. Finally, press the cover plate 3 onto the top of the housing 1 and lock it in place with the buckle. At this point, the single-sided center of gravity counterweight of the aircraft is completed. Repeat the above steps to complete another counterweight on the symmetrical side, thus completing the test flight counterweight work for the overall pitch and roll directions.

[0065] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for counterweighting in flight performance testing of large unmanned cargo aircraft, characterized in that, It includes the following steps: Based on the empty machine's center of gravity position, the required center of gravity adjustment amount, and the required installation position of the counterweight, the required change in torque for movement is obtained; The required counterweight is obtained based on the required adjustment of the center of gravity and the required change in torque for movement; Install the counterweight box in the preset position and place the corresponding counterweight (2) of the required counterweight weight in the counterweight box to achieve center of gravity adjustment in the pitch and roll directions.

2. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 1, characterized in that, Based on the empty machine's center of gravity position, the required center of gravity adjustment amount, and the required installation position of the counterweight, the required change in torque for movement is obtained, specifically including: The target center of gravity adjustment position is obtained based on the required adjustment amount and the required installation position of the counterweight. Based on the empty aircraft center of gravity position, the target center of gravity adjustment position, and the empty aircraft lever arm, obtain the target lever arm required for adjusting the center of gravity; Based on the target lever arm required to adjust the center of gravity, the change in torque required for the movement is obtained.

3. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 2, characterized in that, Obtaining the target lever arm required for adjusting the center of gravity specifically includes: The target lever arm required to adjust the center of gravity is calculated using a first calculation formula, wherein the first calculation formula is: ； Among them, a target The target lever arm required to adjust the center of gravity is defined as follows: %MAC is the percentage of the mean aerodynamic chord, A1 is the target center of gravity adjustment position, A0 is the empty center of gravity position, and a0 is the lever arm when the aircraft is empty, which is the distance between the empty center of gravity and the aircraft coordinate reference plane.

4. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 3, characterized in that, Based on the required adjustment of the center of gravity and the required change in torque for movement, the required counterweight is obtained, specifically including: The required weight is calculated using a second calculation formula, wherein the second calculation formula is: ； Right now ; Where ∆W is the required counterweight, W0 is the empty weight, and a1 is the torque required to install the counterweight box.

5. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 4, characterized in that, To achieve center of gravity adjustment in both pitch and roll directions, specifically including: The required counterweight is calculated to adjust the center of gravity in the pitch direction. The counterweight box is designed to be installed symmetrically on both sides. The required counterweight is evenly distributed to the left and right sides of the symmetrical counterweight box to adjust the center of gravity in the direction of roll.

6. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 1, characterized in that: The counterweight box includes a box body (1) and a cover plate (3) is provided on the box body (1). When the counterweight box is in the center of gravity adjustment state, the cover plate (3) is located on the top of the box body (1) and the cover plate (3) and the box body (1) form a sealed space. When the counterweight box is in the push-pull use state, the cover plate (3) is located at the bottom of the box body (1). A caster wheel (302) is detachably installed on the cover plate (3).

7. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 6, characterized in that: The box (1) is provided with a partition plate (101) inside, which divides the sealed space into multiple storage spaces for placing counterweights (2); a fixing corner piece (102) is provided between the partition plate (101) and the inner wall of the box (1).

8. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 6, characterized in that: The bottom of the box (1) is provided with a mounting hole (103) and a countersunk screw is provided in the mounting hole (103); when the counterweight box is in the push-pull use state, the box (1) moves along the freight slide rail (4); when the counterweight box is in the center of gravity adjustment state, the box (1) is fixedly connected to the fixed base (5) on the side of the freight slide rail (4) by the countersunk screw.

9. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 6, characterized in that: The cover plate (3) is provided with a hollow cylinder (303) and a round hole is provided on the hollow cylinder (303). A support column (3022) is provided on the rotation shaft (3021) of the universal wheel (302). The support column (3022) is telescopic. The rotation shaft (3021) is inserted into the hollow cylinder (303), and the support column (3022) is engaged with the round hole.

10. The counterweight method for flight performance testing of large unmanned cargo aircraft as described in claim 6, characterized in that: The side of the box (1) is provided with a handle (106) through a reinforcing plate (105).

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