Full-aircraft drop test method and device for principle prototype of large-anti-back headstand angle aircraft

Abstract

The invention discloses a full-aircraft drop test method and a full-aircraft drop test device for a principle prototype of a large anti-back headstand angle aircraft, and particularly relates to a method and a test device for keeping the time of the principle prototype consistent with the time of a landing dynamic process of an original aircraft in a drop test. On the basis that lifting and releasing of a small-size principle prototype can be achieved, equivalent simulation of dynamic response in the time period from the main landing gear to the front landing gear in the landing process of the principle prototype can be achieved in cooperation with a shrinkage specific gravity acceleration loading method and an aerodynamic force applying method, and therefore a full-aircraft drop test can be conducted in a limited site. According to the technical scheme, the device comprises a lifting and releasing device, a shrinkage specific gravity acceleration applying device, an aerodynamic force applying device and a force measuring platform; according to the invention, the consistency of a small-size principle prototype in the time period from the main landing gear to the front landing gear to the original aircraft can be realized.

Description

Technical Field

[0001] The present invention specifically relates to a method and a test device suitable for large anti-inversion angle aircraft, which simulates the gravity acceleration of a small-sized principle prototype and the aerodynamic force in a drop shock test to achieve the principle prototype maintaining the same landing dynamic process time with the original aircraft in the drop shock test. Background Art

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

[0003] In the full-aircraft drop test, since the test object aircraft has a large external size and the laboratory space is limited, it is necessary to consider using a small-sized prototype for the test. At the same time, due to the limitations of the test site, the heading speed of the test object during landing cannot be achieved during the test, that is, it cannot meet its aerodynamic requirements such as lift during landing. Therefore, it is necessary to apply an external force at its aerodynamic center to simulate the aerodynamic force on the test object. In existing full-aircraft drop tests, the lift simulation method is generally used to simulate the lift of the test object, but the external force usually applied is an average lift obtained by calculating the lift work during the landing process, and cannot effectively simulate the lift change during the landing process as the aircraft attitude changes.

[0004] For aircraft with an anti-inversion angle greater than 30° (such as some aerospace planes), the front landing gear will accelerate and sink during the landing phase. Therefore, the full-aircraft drop test of the prototype needs to effectively simulate its landing motion state, especially the motion state from the main landing gear touching the ground to the front landing gear touching the ground. In the existing full-aircraft drop test of the prototype, the consistency of the load size and dynamic response of the prototype and the original aircraft can be achieved under a certain ratio, but the consistency in time, especially the consistency in time from the main landing gear touching the ground to the front landing gear touching the ground, has not yet been achieved. Therefore, it is impossible to use the prototype to effectively simulate the dynamic response of this stage. Summary of the invention

[0005] In view of the above problems, the present invention proposes a whole-aircraft drop shock test method and device for a principle prototype of an aircraft with a large anti-inversion angle. On the basis of being able to realize the lifting and release of a small-sized principle prototype, combined with a loading method of scaled-down gravity acceleration and a method of applying aerodynamic force (lift and pitch moment), an equivalent simulation of the dynamic response of the principle prototype during the landing process from the main landing gear touching the ground to the front landing gear touching the ground can be achieved, so as to realize the whole-aircraft drop shock test in a limited field.

[0006] The technical solution of the present invention is: comprising a lifting and releasing device 3, a scaled gravity acceleration applying device 1, an aerodynamic applying device 2 and a force measuring platform 7; The scaled gravity acceleration applying device 1 is connected to the center of gravity of the small-sized principle prototype 4, and the tension applied to the center of gravity is adjusted so that the magnitude of the force applied to the small-sized principle prototype 4 at the center of gravity conforms to the scaled gravity; the aerodynamic applying device 2 is connected to the aerodynamic center of the small-sized principle prototype 4, and the pitch angle of the small-sized principle prototype 4 is changed by adjusting the tension applied to the aerodynamic center, and the tension is equal to 0 when the pitch angle is less than the set angle; the lifting and releasing device 3 is connected to the head and tail of the small-sized principle prototype 4, and the small-sized principle prototype 4 is lifted as a whole to a set height by the lifting and releasing device 3 and then released; The force measuring platform 7 includes force sensors arranged under each landing gear of the small-size principle prototype 4, and the vertical force of each landing gear is measured by the force measuring platform 7.

[0007] like Figure 1 , 2 As shown in Figure 3, the scaled gravity acceleration applying 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 mounted on the crossbeam 5 supported by the triangular bracket 6. The pulley block 1.2 includes a movable pulley 1.2.1 mounted on the bottom end of the cylinder body of the longitudinal cylinder 1.1 and a fixed pulley 1.2.2 mounted 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-scale principle prototype 4. The center of gravity position hook 4.1 is fixedly mounted at the center of gravity of the small-scale principle prototype 4.

[0008] There are a plurality of fixed pulleys 1.2.2 and movable pulleys 1.2.1, 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.

[0009] like Figure 1 , 2As shown in Figures 4, 5 and 6, the aerodynamic force applying 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 installed 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 and is fixedly connected to the crossbeam 5. The longitudinal slide rail 2.3 is vertically arranged and fixedly connected to the crossbeam 5. There is a gap between the transverse slide rail 2.2 and the longitudinal slide rail 2.3. The distance between the horizontal slide rail 2.2 and the longitudinal slide rail 2.3 is slidably connected with a slider, and the two ends of the connecting rod 2.5 are respectively hinged with two sliders. The slider on the horizontal slide rail 2.2 is also connected to the cylinder rod of the horizontal cylinder 2.1, and the slider on the longitudinal slide rail 2.3 is also connected to the top 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-size principle prototype 4. The aerodynamic center hook 4.2 is fixedly installed at the aerodynamic center of the small-size principle prototype 4.

[0010] like Figure 1 , 2 As shown in , 7, the lifting and releasing device 3 includes a hand winch 3.1, an electromagnet 3.2 and an adsorption iron block 3.3. The hand winch 3.1 is installed above the head or tail of the small-size principle prototype 4, and the adsorption iron block 3.3 is installed at the bottom of the hand winch 3.1. The adsorption iron block 3.3 is driven to reciprocate and rise and fall by the hand winch 3.1, and the electromagnet 3.2 is fixedly installed at the head or tail of the small-size principle prototype 4.

[0011] Carry out the test as follows: The electromagnets are installed at the head and tail of the small-size prototype. Before the test begins, the electromagnets are energized to attract the iron block connected to the hook of the hand chain hoist. The small-size prototype is lifted by the hand chain hoist until the main landing gear keeps its tires in contact with the force measuring platform and is not compressed, and the front landing gear is off the ground, so that the small-size prototype reaches the pitch angle required for the test; Keep the small-scale prototype in this posture, tighten the center of gravity connecting rope and the aerodynamic center connecting rope respectively; then use the hand chain hoist to synchronously lift the front landing gear and main landing gear of the small-scale prototype to the release height required for the test touchdown speed, and keep the pitch angle unchanged; At the beginning of the test, the electromagnet is powered off to make the small-scale prototype perform free fall to achieve the required descent speed of the experiment; when the main landing gear tire contacts the force measuring platform, the gravity center connecting rope and the aerodynamic center connecting rope are tightened again, and the force measuring platform and other sensors start to collect test data; The tension on the rope connecting the center of gravity is kept constant by using a scaled gravity acceleration applying device to simulate the scaled gravity of the small-scale principle prototype; the tension on the rope connecting the aerodynamic center is gradually reduced from a certain value to 0 as the small-scale principle prototype descends and lies flat by using an aerodynamic applying device to simulate the aerodynamic force of the small-scale principle prototype; After the front landing gear touches the ground and completes the buffering, the data collection ends and the test ends.

[0012] Beneficial effects of the present invention 1. It can realize the equivalent reduction ratio of gravity acceleration of small-sized prototype in drop shock test; Second, it can realize equivalent simulation of the lift change with attitude of a small-sized prototype during landing; 3. A small-scale prototype can be made to maintain time consistency with the original aircraft during the period from the main landing gear touching the ground to the front landing gear touching the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The test device is shown in Figure 1. Figure 1 (front view); Figure 2 The test device is shown in Figure 1. Figure 2 (Rear view); Figure 3 It is a schematic diagram of a scaled-down gravity acceleration applying device; Figure 4 is a schematic diagram of an aerodynamic force application device; Figure 5 The working principle of the aerodynamic force application device is explained Figure 1 (Lift is not in 0 state); Figure 6 The working principle of the aerodynamic force application device is explained Figure 2 (Lift is 0 state); Figure 7 It is a schematic diagram of the lifting and releasing device located at the head of the small-scale prototype; Figure 8 It is a schematic diagram of the lifting and releasing device located at the tail of the small-scale prototype; Fig. 9 This is a schematic diagram of the small-scale principle prototype after lifting and then releasing.

[0014] Names of the numbers in the figure: 1. Scaled gravity acceleration applying 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 applying device, 2.1. Horizontal cylinder, 2.2. Horizontal 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 chain hoist, 3.2. Electromagnet, 3.3 Adsorption iron block, 4. Small-size principle prototype, 4.1. Center of gravity position hook, 4.2. Aerodynamic center hook, 5. Crossbeam, 6. Triangle bracket, 7. Force measuring platform. DETAILED DESCRIPTION

[0015] In order to clearly illustrate the technical features of this patent, this patent is elaborated in detail below through a specific implementation method and in combination with its accompanying drawings.

[0016] The overall case 1-2 includes a lifting and releasing device 3, a scaled gravity acceleration applying device 1, an aerodynamic applying device 2 and a force measuring platform 7 arranged in sequence; The scaled gravity acceleration applying device 1 is connected to the center of gravity of the small-sized principle prototype 4, and the tension applied to the center of gravity is adjusted so that the magnitude of the force applied to the small-sized principle prototype 4 at the center of gravity conforms to the scaled gravity; the aerodynamic applying device 2 is connected to the aerodynamic center of the small-sized principle prototype 4, and the pitch angle of the small-sized principle prototype 4 is changed by adjusting the tension applied to the aerodynamic center, and the tension is equal to 0 when the pitch angle is less than the set angle; the lifting and releasing device 3 is connected to the head and tail of the small-sized principle prototype 4, and the small-sized principle prototype 4 is lifted as a whole to a set height by the lifting and releasing device 3 and then released; The force measuring platform 7 includes force sensors arranged under each landing gear of the small-size principle prototype 4, and the vertical force of each landing gear is measured by the force measuring platform 7.

[0017] In the above: like Figure 1 , 2 As shown in Figure 3, the scaled gravity acceleration applying 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 mounted on the crossbeam 5 supported by the triangular bracket 6. The pulley block 1.2 includes a movable pulley 1.2.1 mounted on the bottom end of the cylinder body of the longitudinal cylinder 1.1 and a fixed pulley 1.2.2 mounted 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-scale principle prototype 4. The center of gravity position hook 4.1 is fixedly mounted at the center of gravity of the small-scale principle prototype 4.

[0018] There are several fixed pulleys 1.2.2 and movable pulleys 1.2.1, and the center of gravity connecting rope 1.3 is alternately passed 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 pulley 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 applied to the small-size principle prototype 4 at the center of gravity meets the scaled gravity.

[0019] like Figure 1 , 2 As shown in Figures 4, 5 and 6, the aerodynamic force applying 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 installed 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 and is fixedly connected to the crossbeam 5. The longitudinal slide rail 2.3 is vertically arranged and fixedly connected to the crossbeam 5. There is a gap between the transverse slide rail 2.2 and the longitudinal slide rail 2.3. The distance between the horizontal slide rail 2.2 and the longitudinal slide rail 2.3 is slidably connected with a slider, and the two ends of the connecting rod 2.5 are respectively hinged with two sliders. The slider on the horizontal slide rail 2.2 is also connected to the cylinder rod of the horizontal cylinder 2.1, and the slider on the longitudinal slide rail 2.3 is also connected to the top 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-size principle prototype 4. The aerodynamic center hook 4.2 is fixedly installed at the aerodynamic center of the small-size principle prototype 4.

[0020] like Figure 1 , 2 As shown in Figures 7 and 8, the lifting and releasing device 3 includes a hand winch 3.1, an electromagnet 3.2 and an adsorption iron block 3.3. The hand winch 3.1 is installed above the head or tail of the small-size principle prototype 4, and the adsorption iron block 3.3 is installed at the bottom of the hand winch 3.1. The adsorption iron block 3.3 is driven to reciprocate and rise and fall by the hand winch 3.1, and the electromagnet 3.2 is fixedly installed at the head or tail of the small-size principle prototype 4.

[0021] The working principle of each part in this case is as follows: According to the similarity principle, in order to ensure the time consistency between the scaled-down small-scale prototype and the original aircraft, it is necessary to achieve that the ratio of the acceleration of the small-scale prototype and the original aircraft is equal to the ratio of their geometric lengths. Therefore, a force in the direction opposite to gravity is applied at the center of gravity of the small-scale prototype to simulate its gravity acceleration in the test. The specific implementation method is that the scaled-down gravity acceleration applying device 1 is installed on the crossbeam 5 supported by the triangular bracket 6. The lower end of the center of gravity connecting rope 1.3 is connected to the hook 4.1 at the center of gravity position above the small-scale prototype 4, and the upper end passes through the pulley block 1.2 and is connected to the crossbeam 5. The movable pulley 1.2.1 in the pulley block 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 applied to the center of gravity of the small-size principle prototype 4 meets the scaled gravity.

[0022] After the main landing gear touches the ground, the attack angle of the aircraft is equal to the pitch angle, and the lift varies linearly with the pitch angle. Therefore, a force whose magnitude varies with the pitch angle and is equal to 0 when the pitch angle is less than a certain angle is applied to the aerodynamic center of the small-scale principle prototype to simulate its lift in the experiment. The specific implementation method is that the aerodynamic force application device 2 is installed on the crossbeam 5 supported by the 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-scale principle prototype 4, and the upper end is connected to the slider on the longitudinal slide rail 2.3. The longitudinal slide rail 2.3 and the slider on the transverse slide rail 2.2 are connected by a connecting rod 2.5 to form a slider connecting rod 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 0, and 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 0. By adjusting the air pressure in the transverse cylinder 2.1, the tension on the aerodynamic center connecting rope 2.4 can be changed.

[0023] The touchdown speed of the small-scale prototype in the test can be controlled by lifting it to a certain height and then releasing it, converting the gravitational potential energy into kinetic energy. The pitch attitude can be controlled by adjusting the pitch angle of the small-scale prototype when it is released. The specific implementation method is: The electromagnet 3.2 is installed at the head and tail of the small-size prototype 4. Before the test begins, the electromagnet 3.2 is energized to adsorb the adsorption iron block 3.3 connected to the hook of the hand winch 3.1, and the small-size prototype 4 is lifted by the hand winch until the main landing gear keeps its tires in contact with the force measuring platform 7 but not compressed, and the front landing gear is off the ground, so that the small-size prototype 4 reaches the pitch angle required for the test.

[0024] Keeping the small-scale prototype in this posture, tighten the gravity center connecting rope 1.3 and the aerodynamic center connecting rope 2.4 respectively. Then, the front landing gear and the main landing gear of the small-scale prototype 4 are synchronously lifted to the release height required by the test touchdown speed through the hand chain hoist 3.1, and the pitch angle is kept unchanged.

[0025] Then the test starts, the electromagnet 3.2 is powered off, and the small-scale principle prototype 4 is made to perform free fall motion to achieve the descending speed required for the experiment.

[0026] When the main landing gear tire contacts the force measuring platform 7, the gravity center connecting rope 1.3 and the aerodynamic center connecting rope 2.4 are tensioned again, and the force measuring platform 7 and other sensors start to collect test data (speed sensors, acceleration sensors, position sensors and visual monitoring equipment are arranged as required).

[0027] The tension on the gravity center connecting rope 1.3 is kept constant by the scaled gravity acceleration applying device 1 to simulate the scaled gravity of the small-scale principle prototype 4; the tension on the aerodynamic center connecting rope 2.4 is gradually reduced from a certain value to 0 as the small-scale principle prototype 4 descends and lies flat by the aerodynamic applying device 2 to simulate the aerodynamic force (lift and pitch moment) of the small-scale principle prototype 4. In the process, the longitudinal cylinder 1.1 and the transverse cylinder 2.1 will gradually extend passively under the influence of the gravity of the small-scale principle prototype 4.

[0028] Then, after the front landing gear touches the ground and completes the buffering, the data collection ends and the test ends.

[0029] There are many specific implementation ways of the present invention. The above is only the preferred implementation mode of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A full-machine drop shock test device for a principle prototype of a large anti-backward inverted angle aircraft, characterized in that: It comprises a lifting and releasing device (3), a scaled-down gravity acceleration applying device (1), an aerodynamic force applying device (2) and a force measuring platform (7); The scaled gravity acceleration applying device (1) is connected to the center of gravity of the small-sized principle prototype (4), and by adjusting the tension applied to the center of gravity, the magnitude of the force applied to the small-sized principle prototype (4) at the center of gravity is made to conform to the scaled gravity; the aerodynamic applying device (2) is connected to the aerodynamic center of the small-sized principle prototype (4), and by adjusting the tension applied to the aerodynamic center, the pitch angle of the small-sized principle prototype (4) is changed, and when the pitch angle is less than a set angle, the tension is equal to 0; the lifting and releasing device (3) is connected to the head and tail of the small-sized principle prototype (4), and the small-sized principle prototype (4) is lifted as a whole to a set height by the lifting and releasing device (3) and then released; The force measuring platform (7) comprises a force sensor arranged under each landing gear of the small-sized principle prototype (4), and the force in the vertical direction of each landing gear is measured through the force measuring platform (7).

2. The whole-machine drop shock test device for a large anti-backward inversion angle aircraft principle prototype according to claim 1 is characterized in that: The scaled gravity acceleration applying device (1) comprises a longitudinal cylinder (1.1), a pulley block (1.2) and a gravity center connecting rope (1.3); the longitudinal cylinder (1.1) is arranged vertically, and its cylinder body is fixedly mounted on a crossbeam (5) supported by a triangular bracket (6); the pulley block (1.2) comprises a movable pulley (1.2.1) mounted on the bottom end of the cylinder body of the longitudinal cylinder (1.1) and a fixed pulley (1.2.2) mounted on the crossbeam (5); one end of the gravity center 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 a gravity center position hook (4.1) on a small-sized principle prototype (4); the gravity center position hook (4.1) is fixedly mounted at the gravity center of the small-sized principle prototype (4).

3. The whole-machine drop shock test device for a large anti-backward inversion angle aircraft principle prototype according to claim 2 is characterized in that: A plurality of the 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).

4. The whole-machine drop shock test device for a large anti-backward inversion angle aircraft principle prototype according to claim 1 is characterized in that: The aerodynamic force application device (2) comprises 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 arranged horizontally, 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) beside the transverse cylinder (2.1) and is fixedly connected to the crossbeam (5); the longitudinal slide rail (2.3) is arranged vertically 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). The invention relates to a method for manufacturing a small-sized principle prototype machine (4) and a small-sized principle prototype machine (4). The invention relates to a method for manufacturing a small-sized principle prototype machine (4) and a small-sized principle prototype machine (4). The invention relates to a method for manufacturing a small-sized principle prototype machine (4) and a small-sized principle prototype machine (4) comprising: ...

5. The whole-machine drop shock test device for a large anti-backward inversion angle aircraft principle prototype according to claim 1 is characterized in that: The lifting and releasing device (3) comprises 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 principle prototype (4); the adsorption iron block (3.3) is installed at the bottom of the hand chain hoist (3.1); the adsorption iron block (3.3) is driven to reciprocate and rise and fall by the hand chain hoist (3.1); and the electromagnet (3.2) is fixedly installed at the head or tail of the small-sized principle prototype (4).

6. A full-machine drop shock test method for a prototype aircraft with a large anti-backward inversion angle based on the test device of claim 1, characterized in that: Carry out the test as follows: The electromagnets are installed at the head and tail of the small-size prototype. Before the test begins, the electromagnets are energized to attract the iron block connected to the hook of the hand chain hoist. The small-size prototype is lifted by the hand chain hoist until the main landing gear keeps its tires in contact with the force measuring platform and is not compressed, and the front landing gear is off the ground, so that the small-size prototype reaches the pitch angle required for the test; Keep the small-scale prototype in this posture, tighten the center of gravity connecting rope and the aerodynamic center connecting rope respectively; then use the hand chain hoist to synchronously lift the front landing gear and main landing gear of the small-scale prototype to the release height required for the test touchdown speed, and keep the pitch angle unchanged; At the beginning of the test, the electromagnet is powered off to make the small-scale prototype perform free fall to achieve the required descent speed of the experiment; when the main landing gear tire contacts the force measuring platform, the gravity center connecting rope and the aerodynamic center connecting rope are tightened again, and the force measuring platform and other sensors start to collect test data; The tension on the gravity center connecting rope is kept constant by using a scaled-down gravity acceleration applying device to simulate the scaled-down gravity of the small-scale principle prototype. The aerodynamic force applying device is used to gradually reduce the tension on the aerodynamic center connecting rope from a certain value to 0 as the small-scale principle prototype descends and lies flat, so as to simulate the aerodynamic force on the small-scale principle prototype; After the front landing gear touches the ground and completes the buffering, the data collection ends and the test ends.

Images