A method and device for full machine drop test of a large anti-tumble angle aircraft prototype

Abstract

The application discloses a kind of big anti-reverse angle aircraft principle prototype whole machine drop test method and device, specifically relates to a kind of method and test device for achieving principle prototype in drop test with original aircraft landing dynamic process time consistent.In the basis that small size principle prototype can be realized lifting and releasing, cooperate with the loading method of scaled gravity acceleration and the application method of air power, the dynamic response of the time period of main landing gear landing to front landing gear landing in principle prototype landing process can be realized equivalent simulation, to realize the whole machine drop test under limited field.The technical scheme of the application is: including lifting and releasing device, scaled gravity acceleration applying device, air power applying device and force platform;The application can realize the consistency of small size principle prototype in the time period of main landing gear landing to front landing gear landing with original aircraft.

Description

Technical Field

[0001] Specifically, this invention relates to a method and test apparatus for a large rear-inverted angle aircraft, which simulates the gravitational acceleration of a small-sized prototype and the aerodynamics in a drop test to ensure that the prototype maintains the same landing dynamic process time as the original aircraft in the drop test. Background Technology

[0002] The full-aircraft drop test is an important test method for testing the structural dynamic load and dynamic response of an aircraft during landing, as well as the functional reliability of airborne equipment under impact conditions, in a laboratory environment.

[0003] In full-scale drop tests, due to the large size of the test aircraft and the limited space in the laboratory, it is necessary to consider using a small-sized prototype. Furthermore, due to the limitations of the test site, the yaw velocity at landing cannot be replicated, thus failing to meet the aerodynamic requirements such as lift during landing. Therefore, it is necessary to apply an external force to its aerodynamic center to simulate the aerodynamic forces acting on the test aircraft. Existing full-scale drop tests generally use the lift simulation method to simulate the lift of the test aircraft. However, the applied external force is usually an average lift obtained by calculating the lift work during landing, which cannot effectively simulate the change in lift as the aircraft's attitude changes during landing.

[0004] For aircraft with a rear-inversion angle greater than 30° (such as some spaceplanes), there is an accelerated sinking of the nose landing gear during the landing phase. Therefore, the full-scale drop test of its prototype needs to effectively simulate its landing motion, especially the motion from the main landing gear touchdown to the nose landing gear touchdown. Existing full-scale drop tests of prototypes can achieve consistency between the prototype and the original aircraft in terms of load magnitude and dynamic response at a certain ratio, but consistency in time, especially in the time phase from the main landing gear touchdown to the nose landing gear touchdown, has not yet been achieved. Therefore, it is impossible to effectively simulate the dynamic response of this phase using the prototype. Summary of the Invention

[0005] To address the above problems, this invention proposes a method and apparatus for full-aircraft drop test of a large anti-backward tilt angle aircraft prototype. Based on the ability to lift and release a small-sized prototype, and in conjunction with a scaling-down gravity acceleration loading method and an aerodynamic (lift and pitch moment) application method, it is possible to achieve an equivalent simulation of the dynamic response of the prototype during the landing process from the main landing gear touchdown to the nose landing gear touchdown, so as to realize the full-aircraft drop test in a limited space.

[0006] The technical solution of the present invention includes a lifting and releasing device 3, a scaled-down gravity acceleration application device 1, an aerodynamic application device 2, and a force measuring platform 7.

[0007] The scaled-down gravity acceleration application device 1 is connected to the center of gravity of the small-sized prototype 4. By adjusting the tension applied to the center of gravity, the magnitude of the force on the small-sized prototype 4 at the center of gravity is made to match the scaled-down gravity. The aerodynamic application device 2 is connected to the aerodynamic center of the small-sized prototype 4. By adjusting the tension applied to the aerodynamic center, the pitch angle of the small-sized prototype 4 is changed, and the tension is equal to 0 when the pitch angle is less than a set angle. The lifting and releasing device 3 is connected to the head and tail of the small-sized prototype 4. The small-sized prototype 4 is lifted to a set height and then released.

[0008] The force measuring platform 7 includes force sensors arranged under each landing gear of the small-sized prototype 4, which measure the vertical force of each landing gear through the force measuring platform 7.

[0009] like Figure 1 , 2 As shown in Figure 3, the scaled-down gravity acceleration application device 1 includes a longitudinal cylinder 1.1, a pulley block 1.2, and a center-of-gravity connecting rope 1.3. The longitudinal cylinder 1.1 is vertically arranged, and its cylinder body is fixedly installed on the crossbeam 5 supported by the triangular bracket 6. The pulley block 1.2 includes a movable pulley 1.2.1 installed at the bottom of the cylinder body of the longitudinal cylinder 1.1 and a fixed pulley 1.2.2 installed on the crossbeam 5. One end of the center-of-gravity connecting rope 1.3 is fixedly connected to the crossbeam 5, and after passing through the movable pulley 1.2.1 and the fixed pulley 1.2.2 in sequence, it is hooked onto the center-of-gravity position hook 4.1 on the small-sized prototype 4. The center-of-gravity position hook 4.1 is fixedly installed at the center of gravity of the small-sized prototype 4.

[0010] Several fixed pulleys 1.2.2 and movable pulleys 1.2.1 are provided, and the center-of-gravity connecting rope 1.3 alternately passes around each fixed pulley 1.2.2 and each movable pulley 1.2.1.

[0011] like Figure 1 , 2As shown in Figures 4, 5, and 6, the aerodynamic application device 2 includes a transverse cylinder 2.1, a transverse slide rail 2.2, a longitudinal slide rail 2.3, an aerodynamic center connecting rope 2.4, and a connecting rod 2.5. The transverse cylinder 2.1 is horizontally arranged, and its cylinder body is fixedly mounted on a crossbeam 5 supported by a triangular bracket 6. The transverse slide rail 2.2 is arranged in the same direction as the transverse cylinder 2.1 on one side of the transverse cylinder 2.1 and is fixedly connected to the crossbeam 5. The longitudinal slide rail 2.3 is vertically arranged and fixedly connected to the crossbeam 5. A gap is left between the transverse slide rail 2.2 and the longitudinal slide rail 2.3. A slider is slidably connected to both the transverse slide rail 2.2 and the longitudinal slide rail 2.3. Two sliders are hinged to both ends of the connecting rod 2.5. The slider on the transverse slide rail 2.2 is also connected to the cylinder rod of the transverse cylinder 2.1. The slider on the longitudinal slide rail 2.3 is also connected to the top end of the aerodynamic center connecting rope 2.4. The bottom end of the aerodynamic center connecting rope 2.4 is hooked onto the aerodynamic center hook 4.2 on the small-sized prototype 4. The aerodynamic center hook 4.2 is fixedly installed at the aerodynamic center of the small-sized prototype 4.

[0012] like Figure 1 , 2 As shown in Figures 7 and 8, the lifting and releasing device 3 includes a hand chain hoist 3.1, an electromagnet 3.2, and an adsorption iron block 3.3. The hand chain hoist 3.1 is installed above the head or tail of the small-sized prototype 4, and the adsorption iron block 3.3 is installed at the bottom of the hand chain hoist 3.1. The hand chain hoist 3.1 drives the adsorption iron block 3.3 to reciprocate up and down. The electromagnet 3.2 is fixedly installed at the head or tail of the small-sized prototype 4.

[0013] Conduct the experiment using the following method:

[0014] Electromagnets are installed at the head and tail of the small prototype. Before the test begins, the electromagnets are energized so that they attract the iron block connected to the hook of the hand chain hoist. The small prototype is then lifted by the hand chain hoist until the main landing gear keeps its tires in contact with the force measuring platform without compression, while the front landing gear is off the ground, so that the small prototype reaches the pitch angle required for the test.

[0015] While maintaining the small-sized prototype in this posture, tension the center of gravity connecting rope and the aerodynamic center connecting rope respectively; then, use a hand-operated hoist to synchronously raise the front landing gear and main landing gear of the small-sized prototype to the release height required for the test's grounding speed, while keeping the pitch angle constant;

[0016] At the start of the experiment, the electromagnet was de-energized, allowing the small-sized prototype to undergo free fall to achieve the required descent speed. Once the main landing gear tires contacted the force measurement platform, the center of gravity connecting rope and the aerodynamic center connecting rope were tensioned again, and the force measurement platform and other sensors began to collect experimental data.

[0017] The scaled-down gravity of the prototype is simulated by keeping the tension on the center-of-gravity connecting rope constant through a scaled-down gravity acceleration application device; the aerodynamic force of the prototype is simulated by gradually decreasing the tension on the aerodynamic center connecting rope from a certain value to 0 as the prototype descends and flattens through an aerodynamic application device.

[0018] Once the front landing gear has touched down and cushioned the impact, data acquisition will cease, and the test will end.

[0019] Beneficial effects of the present invention

[0020] 1. It can achieve an equivalent scaling of the gravitational acceleration of a small-sized prototype in a drop test;

[0021] Second, it can realize the equivalent simulation of the change of lift with attitude during the landing process of a small-sized prototype;

[0022] Third, it can ensure that the time interval between the main landing gear touchdown and the nose landing gear touchdown of the small-sized prototype is consistent with that of the original aircraft. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the experimental setup. Figure 1 (Front-up view);

[0024] Figure 2 This is a schematic diagram of the experimental setup. Figure 2 (Rear view);

[0025] Figure 3 This is a schematic diagram of a scaled-down gravitational acceleration application device;

[0026] Figure 4 This is a schematic diagram of an aerodynamic application device;

[0027] Figure 5 Explanation of the working principle of the aerodynamic application device Figure 1 (Lift is not zero);

[0028] Figure 6 Explanation of the working principle of the aerodynamic application device Figure 2 (Lift is 0);

[0029] Figure 7 This is a schematic diagram of the lifting and releasing device located at the head of the small-sized prototype.

[0030] Figure 8 This is a schematic diagram of the lifting and releasing device located at the rear of the small-sized prototype.

[0031] Figure 9 This is a schematic diagram of the small-sized prototype in the state of being lifted and then released.

[0032] The following are the labels in the diagram: 1. Scaled-down gravity acceleration application device, 1.1. Longitudinal cylinder, 1.2. Pulley block, 1.2.1. Movable pulley, 1.2.2. Fixed pulley, 1.3. Center of gravity connecting rope; 2. Aerodynamic application device, 2.1. Transverse cylinder, 2.2. Transverse slide rail, 2.3. Longitudinal slide rail, 2.4. Aerodynamic center connecting rope, 2.5. Connecting rod; 3. Lifting and releasing device, 3.1. Hand-operated hoist, 3.2. Electromagnet, 3.3 Adsorbed iron block; 4. Small-sized prototype, 4.1. Center of gravity position hook, 4.2. Aerodynamic center hook; 5. Crossbeam; 6. Triangular bracket; 7. Force measuring platform. Detailed Implementation

[0033] To clearly illustrate the technical features of this patent, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings.

[0034] The overall situation of this case is as follows: Figure 1-2 As shown, it includes a lifting and releasing device 3, a scaled-down gravity acceleration application device 1, an aerodynamic application device 2, and a force measuring platform 7 arranged in sequence.

[0035] The scaled-down gravity acceleration application device 1 is connected to the center of gravity of the small-sized prototype 4. By adjusting the tension applied to the center of gravity, the magnitude of the force on the small-sized prototype 4 at the center of gravity is made to match the scaled-down gravity. The aerodynamic application device 2 is connected to the aerodynamic center of the small-sized prototype 4. By adjusting the tension applied to the aerodynamic center, the pitch angle of the small-sized prototype 4 is changed, and the tension is equal to 0 when the pitch angle is less than a set angle. The lifting and releasing device 3 is connected to the head and tail of the small-sized prototype 4. The small-sized prototype 4 is lifted to a set height and then released.

[0036] The force measuring platform 7 includes force sensors arranged under each landing gear of the small-sized prototype 4, which measure the vertical force of each landing gear through the force measuring platform 7.

[0037] In the above:

[0038] like Figure 1 , 2As shown in Figure 3, the scaled-down gravity acceleration application device 1 includes a longitudinal cylinder 1.1, a pulley block 1.2, and a center-of-gravity connecting rope 1.3. The longitudinal cylinder 1.1 is vertically arranged, and its cylinder body is fixedly installed on the crossbeam 5 supported by the triangular bracket 6. The pulley block 1.2 includes a movable pulley 1.2.1 installed at the bottom of the cylinder body of the longitudinal cylinder 1.1 and a fixed pulley 1.2.2 installed on the crossbeam 5. One end of the center-of-gravity connecting rope 1.3 is fixedly connected to the crossbeam 5, and after passing through the movable pulley 1.2.1 and the fixed pulley 1.2.2 in sequence, it is hooked onto the center-of-gravity position hook 4.1 on the small-sized prototype 4. The center-of-gravity position hook 4.1 is fixedly installed at the center of gravity of the small-sized prototype 4.

[0039] Several fixed pulleys 1.2.2 and several movable pulleys 1.2.1 are provided. The center-of-gravity connecting rope 1.3 alternately passes around each fixed pulley 1.2.2 and each movable pulley 1.2.1. By adjusting the air pressure in the longitudinal cylinder 1.1 and the number of movable pulleys 1.2.1 and fixed pulleys 1.2.2 in the pulley group 1.2, the tension applied to the center-of-gravity connecting rope 1.3 can be adjusted so that the magnitude of the force on the small-sized prototype 4 at the center of gravity matches the scaled-down gravity.

[0040] like Figure 1 , 2 As shown in Figures 4, 5, and 6, the aerodynamic application device 2 includes a transverse cylinder 2.1, a transverse slide rail 2.2, a longitudinal slide rail 2.3, an aerodynamic center connecting rope 2.4, and a connecting rod 2.5. The transverse cylinder 2.1 is horizontally arranged, and its cylinder body is fixedly mounted on a crossbeam 5 supported by a triangular bracket 6. The transverse slide rail 2.2 is arranged in the same direction as the transverse cylinder 2.1 on one side of the transverse cylinder 2.1 and is fixedly connected to the crossbeam 5. The longitudinal slide rail 2.3 is vertically arranged and fixedly connected to the crossbeam 5. A gap is left between the transverse slide rail 2.2 and the longitudinal slide rail 2.3. A slider is slidably connected to both the transverse slide rail 2.2 and the longitudinal slide rail 2.3. Two sliders are hinged to both ends of the connecting rod 2.5. The slider on the transverse slide rail 2.2 is also connected to the cylinder rod of the transverse cylinder 2.1. The slider on the longitudinal slide rail 2.3 is also connected to the top end of the aerodynamic center connecting rope 2.4. The bottom end of the aerodynamic center connecting rope 2.4 is hooked onto the aerodynamic center hook 4.2 on the small-sized prototype 4. The aerodynamic center hook 4.2 is fixedly installed at the aerodynamic center of the small-sized prototype 4.

[0041] like Figure 1 , 2As shown in Figures 7 and 8, the lifting and releasing device 3 includes a hand chain hoist 3.1, an electromagnet 3.2, and an adsorption iron block 3.3. The hand chain hoist 3.1 is installed above the head or tail of the small-sized prototype 4, and the adsorption iron block 3.3 is installed at the bottom of the hand chain hoist 3.1. The hand chain hoist 3.1 drives the adsorption iron block 3.3 to reciprocate up and down. The electromagnet 3.2 is fixedly installed at the head or tail of the small-sized prototype 4.

[0042] The working principles of each part in this case are as follows:

[0043] Based on the principle of similarity, to ensure the temporal consistency between the scaled-down prototype and the original aircraft, the ratio of their accelerations must equal the ratio of their geometric lengths. Therefore, a force opposite to gravity is applied at the center of gravity of the scaled-down prototype to simulate its gravitational acceleration during testing. Specifically, the scaled-down gravitational acceleration application device 1 is mounted on a crossbeam 5 supported by a triangular bracket 6. The lower end of the center-of-gravity connecting rope 1.3 is connected to a hook 4.1 at the center of gravity position above the scaled-down prototype 4, and the upper end passes over a pulley system 1.2 and connects to the crossbeam 5. The movable pulley 1.2.1 in the pulley system 1.2 is connected to the piston rod of the longitudinal cylinder 1.1. By adjusting the air pressure in the longitudinal cylinder 1.1 and the number of movable pulleys 1.2.1 and fixed pulleys 1.2.2 in the pulley block 1.2, the tension applied to the center-of-gravity connecting rope 1.3 can be adjusted so that the force on the small-sized prototype 4 at the center of gravity matches the scaled-down gravity.

[0044] After the main landing gear touches the ground, the aircraft's angle of attack equals its pitch angle, and the lift magnitude changes linearly with the pitch angle. Therefore, a force is applied to the aerodynamic center of the small-sized prototype, the magnitude of which varies with the pitch angle, and becomes zero when the pitch angle is less than a certain angle, to simulate the lift in the experiment. Specifically, the aerodynamic application device 2 is mounted on a crossbeam 5 supported by a triangular bracket 6. The lower end of the aerodynamic center connecting rope 2.4 is connected to the aerodynamic center hook 4.2 above the small-sized prototype 4, and the upper end is connected to the slider on the longitudinal slide rail 2.3. The slider on the longitudinal slide rail 2.3 and the transverse slide rail 2.2 are connected by a connecting rod 2.5, forming a slider-linkage mechanism; the slider on the transverse slide rail 2.2 is connected to the transverse cylinder 2.1. When the angle between the connecting rod 2.5 and the ground is not 0°, the tension on the aerodynamic center connecting rope 2.4 is not zero, while when the angle between the connecting rod 2.5 and the ground is 0°, the tension on the aerodynamic center connecting rope 2.4 becomes zero. By adjusting the air pressure in the transverse cylinder 2.1, the tension on the aerodynamic center connecting rope 2.4 can be changed.

[0045] The grounding velocity of the small-scale prototype during testing can be controlled by raising it to a certain height and then releasing it, converting gravitational potential energy into kinetic energy. The pitch attitude can be controlled by adjusting the pitch angle when the small-scale prototype is released. The specific implementation method is as follows:

[0046] Electromagnet 3.2 is installed at the head and tail of the small prototype 4. Before the test begins, electromagnet 3.2 is energized so that it attracts the iron block 3.3 connected to the hook of the hand chain hoist 3.1. The small prototype 4 is then lifted by the hand chain hoist until the main landing gear keeps its tires in contact with the force measuring platform 7 without compression, while the front landing gear is off the ground, so that the small prototype 4 reaches the pitch angle required for the test.

[0047] While maintaining the small-sized prototype in this posture, tension the center-of-gravity connecting rope 1.3 and the aerodynamic center-of-gravity connecting rope 2.4 respectively. Then, using a hand-operated hoist 3.1, synchronously raise the front landing gear and main landing gear of the small-sized prototype 4 to the release height required for the test's grounding speed, while keeping the pitch angle constant.

[0048] Then the experiment begins. The electromagnet 3.2 is de-energized, allowing the small-sized prototype 4 to undergo free fall to achieve the required descent speed for the experiment.

[0049] When the main landing gear tires contact the force measuring platform 7, the center of gravity connecting rope 1.3 and the aerodynamic center connecting rope 2.4 are tensioned again, and the force measuring platform 7 and other sensors begin to collect test data (speed sensors, acceleration sensors, position sensors and visual monitoring equipment are arranged as needed).

[0050] The scaled-down gravity acceleration application device 1 keeps the tension on the center-of-gravity connecting rope 1.3 constant to simulate the scaled-down gravity acting on the prototype 4. The aerodynamic application device 2 gradually reduces the tension on the aerodynamic center connecting rope 2.4 from a certain value to 0 as the prototype 4 descends and flattens, simulating the aerodynamic forces (lift and pitch moment) acting on the prototype 4. During this process, both the longitudinal cylinder 1.1 and the transverse cylinder 2.1 will gradually extend passively under the influence of the gravity of the prototype 4.

[0051] Then, after the front landing gear touches the ground and has completed its cushioning, data acquisition ends, and the test concludes.

[0052] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A full-aircraft drop test device for a large anti-reverse inverted angle aircraft prototype, characterized in that, It includes a lifting and releasing device (3), a scaled-down gravity acceleration application device (1), an aerodynamic application device (2), and a force measuring platform (7); The scaled-down gravity acceleration application device (1) is connected to the center of gravity of the small-sized prototype (4). By adjusting the tension applied to the center of gravity, the magnitude of the force on the small-sized prototype (4) at the center of gravity is made to match the scaled-down gravity. The aerodynamic application device (2) is connected to the aerodynamic center of the small-sized prototype (4). By adjusting the tension applied to the aerodynamic center, the pitch angle of the small-sized prototype (4) is changed, and the tension is equal to 0 when the pitch angle is less than a set angle. The lifting and releasing device (3) is connected to the head and tail of the small-sized prototype (4). The small-sized prototype (4) is lifted to a set height and then released by the lifting and releasing device (3). The force measuring platform (7) includes force sensors arranged under each landing gear of the small-sized prototype (4), and the force measuring platform (7) measures the vertical force of each landing gear. The scaled-down gravity acceleration application device (1) includes a longitudinal cylinder (1.1), a pulley block (1.2), and a center of gravity connecting rope (1.3). The longitudinal cylinder (1.1) is vertically arranged, and its cylinder body is fixedly installed on a crossbeam (5) supported by a triangular bracket (6). The pulley block (1.2) includes a movable pulley (1.2.1) installed at the bottom of the cylinder body of the longitudinal cylinder (1.1) and a fixed pulley (1.2.2) installed on the crossbeam (5). One end of the center of gravity connecting rope (1.3) is fixedly connected to the crossbeam (5), and after passing through the movable pulley (1.2.1) and the fixed pulley (1.2.2) in sequence, it is hooked on the center of gravity position hook (4.1) on the small-sized prototype (4). The center of gravity position hook (4.1) is fixedly installed at the center of gravity of the small-sized prototype (4). The aerodynamic application device (2) includes a transverse cylinder (2.1), a transverse slide rail (2.2), a longitudinal slide rail (2.3), an aerodynamic center connecting rope (2.4), and a connecting rod (2.5). The transverse cylinder (2.1) is horizontally arranged, and its cylinder body is fixedly mounted on a crossbeam (5) supported by a triangular bracket (6). The transverse slide rail (2.2) is arranged in the same direction as the transverse cylinder (2.1) on one side of the transverse cylinder (2.1) and is fixedly connected to the crossbeam (5). The longitudinal slide rail (2.3) is vertically arranged and is fixedly connected to the crossbeam (5). A gap is left between the transverse slide rail (2.2) and the longitudinal slide rail (2.3). A slider is slidably connected to both the transverse slide rail (2.2) and the longitudinal slide rail (2.3). Two sliders are hinged to both ends of the connecting rod (2.5). The slider on the transverse slide rail (2.2) is also connected to the cylinder rod of the transverse cylinder (2.1). The slider on the longitudinal slide rail (2.3) is also connected to the top end of the aerodynamic center connecting rope (2.4). The bottom end of the aerodynamic center connecting rope (2.4) is hooked on the aerodynamic center hook (4.2) on the small-sized prototype (4). The aerodynamic center hook (4.2) is fixedly installed at the aerodynamic center of the small-sized prototype (4).

2. The large anti-reverse inverted angle aircraft prototype full-aircraft drop test device according to claim 1, characterized in that, Several fixed pulleys (1.2.2) and movable pulleys (1.2.1) are provided, and the center-of-gravity connecting rope (1.3) alternately passes around each fixed pulley (1.2.2) and each movable pulley (1.2.1).

3. The large anti-reverse inverted angle aircraft prototype full-aircraft drop test device according to claim 1, characterized in that, The lifting and releasing device (3) includes a hand chain hoist (3.1), an electromagnet (3.2), and an adsorption iron block (3.3). The hand chain hoist (3.1) is installed above the head or tail of the small-sized prototype (4). The adsorption iron block (3.3) is installed at the bottom of the hand chain hoist (3.1). The hand chain hoist (3.1) drives the adsorption iron block (3.3) to move up and down repeatedly. The electromagnet (3.2) is fixedly installed at the head or tail of the small-sized prototype (4).

4. A method for a full-aircraft drop test of a large anti-backward inversion angle aircraft prototype based on the test device described in claim 1, characterized in that, Conduct the experiment using the following method: Electromagnets are installed at the head and tail of the small prototype. Before the test begins, the electromagnets are energized so that they attract the iron block connected to the hook of the hand chain hoist. The small prototype is then lifted by the hand chain hoist until the main landing gear keeps its tires in contact with the force measuring platform without compression, while the front landing gear is off the ground, so that the small prototype reaches the pitch angle required for the test. While maintaining the small-sized prototype in this posture, tension the center of gravity connecting rope and the aerodynamic center connecting rope respectively; then, use a hand-operated hoist to synchronously raise the front landing gear and main landing gear of the small-sized prototype to the release height required for the test's grounding speed, while keeping the pitch angle constant; At the start of the experiment, the electromagnet was de-energized, allowing the small-sized prototype to undergo free fall to achieve the required descent speed. Once the main landing gear tires contacted the force measurement platform, the center of gravity connecting rope and the aerodynamic center connecting rope were tensioned again, and the force measurement platform and other sensors began to collect experimental data. The scaled-down gravity of a prototype is simulated by keeping the tension on the center-of-gravity connecting rope constant through a scaled-down gravity acceleration application device. The aerodynamic forces acting on the small prototype are simulated by using an aerodynamic application device to gradually reduce the tension on the rope connecting the aerodynamic center from a certain value to 0 as the small prototype descends and is leveled. Once the front landing gear has touched down and cushioned the impact, data acquisition will cease, and the test will end.

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