JPH0460488A - Drop tower type microgravity testing device - Google Patents

Abstract

PURPOSE:To regulate microgravity by discharging liquids in a vessel from a liquid discharge port in falling of a testing body, constituting a counterweight of a vessel having a liquid discharge port at the bottom and liquids stored up in the vessel. CONSTITUTION:A counterweight 20 is constructed of a vessel 21, etc., a water discharge port 22 is fitted on the bottom of the vessel 21, and water 23 is stored up in the vessel 21. The water discharge port 22 is shut before the testing start and opened at the same time as the falling of a testing body 15 starts, and the discharge of water 23 is continued during the falling of the testing body 15. Thus, the counterweight 20 becomes slowly smaller in mass, discharging water 23 in falling of the testing body 15. In conjunction, acceleration of the reverse direction is set off against decelaration by air resistance and the accelaration of the testing body 15 can be generated along a fixed or a prescribed pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drop tower type microgravity testing device.

[Conventional technology]

FIG. 2 is a sectional view of a conventional drop tower type microgravity testing device. This device temporarily (approximately 2.5 seconds) generates the microgravity state that occurs inside a spacecraft through free fall to investigate the effects of microgravity on the spacecraft's fuel tank. The equipment used to investigate the behavior of fuel within a tank is shown below. Of course, this device can also be used for other research purposes.

In the figure, 1 is a test base with a height of about 45 m, 2 is sand for braking that is filled in the lower part of the test tower, 3 is a fixed part above the test tower, and 4 is installed in the fixed part. 5 is a T-magnet installed at the lower end of the hanging device, 6 is a test box equipped with an observation device, etc. inside the hanging device, and 7 is a metal piece installed at the top of the test box. This is a suction plate which is attracted by the electromagnet 5 and holds the test box 6.

8 is a lance-shaped brake rod attached to the lower part of the test box 6 and extends downward; 9, 10, 11, and 12 are control equipment and batteries for carrying out experiments and observations in this apparatus, respectively. , telemetry, and video camera. Reference numeral 13 is a model fuel tank of a spacecraft as the object of the experiment conducted using this device, and I4 is a liquid fuel stored in the tank model whose behavior is observed. 1
5 is the total of the above-mentioned items numbered 6 to 14,
Hereinafter, this will be referred to as a test specimen. Pulleys 16 and 17 are held on the hanger 4 and test base 1, respectively; one end of 18 is attached to the upper part of the test box 6; A wire rope to which a counterweight described below is attached, 19
is the counterweight above. This counterweight is a weight made of a metal lump or the like, and has a mass of about 1/15 of the mass of the test specimen 15.

When conducting an experiment using this apparatus, first, the power to the electromagnet 5 holding the test specimen 15 is cut off via the suction plate 7. At this time, the test specimen 15 falls within the tower, and the counterweight 19 is pulled by the test specimen 15 via the wire rope 18 and moves upward. When the test specimen 15 is falling, a microgravity (microweight) state occurs inside the test box 6. The fall of the specimen 15 lasts approximately 2.5 seconds and is stopped by the action of the lance-shaped brake rod 8 when it reaches the sand at the bottom of the tower.

The behavior of the liquid fuel I4 in the microgravity (microweight) state is recorded by the video camera 12. Control equipment 9, battery 10, and telemeter 11 are used to support the above observations.

In the above experiment, when the counterweight 19 was not attached, the test specimen fell completely free, and inside the test box, there was a so-called zero gravity (weightlessness).
A condition occurs. At this time, among the properties of the fluid to be tested, only the influence of surface tension remains, and it is not possible to obtain data on the correlation between surface tension, gravity, and inertial force, which we would like to confirm through experiments. Therefore, rather than allowing the test specimen to fall completely freely, it is necessary to provide some restraint during the fall. The counterweight I9 acts to provide this restraint, allowing the device to perform microgravity rather than weightless tests.

[Problem to be solved by the invention]

In the above test apparatus, the airspeed of the test specimen 15 increases as it falls, and due to the air resistance, a force in the opposite direction to the falling direction acts on the test box 6, which causes the inside of the test box 6 to As a reaction to this, an inertial force is generated in the object that pushes the floor of the test box 6 in the falling direction.

The magnitude of this inertial force increases as the airspeed of the test specimen increases. This inertial force will be added to the microgravity acting on the object in the test box due to the action of the counterweight 19. Therefore, in this device, the microgravity changes between the early stage and late stage of the fall of the test specimen. In other words, the test conditions are not kept constant. Such unintended changes in test conditions are unfavorable for observation.

The present invention solves the above-mentioned drawbacks of the prior art, and provides a microgravity testing device that can generate microgravity applied to the test object inside the test box while the test object is falling, in a constant or predetermined pattern. This is what we are trying to provide.

[Means to solve the problem]

The present invention has solved the above-mentioned problems, and consists of connecting a test specimen equipped with a test object and an observation device inside to a counterweight via a wire rope, and connecting the wire rope with a pulley provided above. In a drop tower type microgravity test device in which the test specimen and a counterweight are suspended through a counterweight and the test specimen is dropped to perform a microgravity test, a container having a liquid discharge hole at the bottom and a liquid stored in the container are used. The present invention relates to a drop tower type microgravity testing apparatus, characterized in that the counterweight is configured from the above, and the liquid in the container is discharged from the liquid discharge hole while the test specimen is falling.

[Effect]

In the device of the invention, during the fall of the test specimen, the counterweight releases liquid and its mass gradually decreases. Assuming there is no deceleration due to air resistance, that is, no acceleration in the opposite direction to the traveling direction, the acceleration of the test specimen increases during its fall as the mass of the counterweight decreases. This therefore cancels out the aforementioned adverse acceleration due to air resistance, so that the acceleration of the test specimen can be adjusted. As a result, microgravity applied to the test object within the test body can be generated along a constant or predetermined pattern.

[Embodiment] FIG. 1 is a sectional view of an embodiment of the present invention. In the figure, 20 is a counterweight having a structure different from conventional counterweights. A container 21 is a part of the counterweight, and is made of metal, for example. 22 is a drainage hole provided at the bottom of the container, and 23 is water stored inside the container. The drainage hole 22 is closed before the test starts, and is opened at the same time as the test specimen 15 starts falling, and water continues to be discharged while the test specimen 15 is falling. The structure and operation of the parts other than those mentioned above are the same as those of the conventional device.

In this device, while the test specimen 15 is falling, the counterweight 20 releases water and its mass gradually decreases. Along with this, assuming there is no deceleration due to air resistance, that is, no acceleration in the opposite direction to the direction of travel, the acceleration of the test object increases during its fall. Therefore, since this cancels out the above-mentioned opposite acceleration due to air resistance, the acceleration of the test specimen can be kept constant or changed in a predetermined manner. By changing the cross-sectional area of the drain hole 22 of the counterweight, the value of acceleration can be adjusted.

In the above example, if the test specimen has a square base with side length 1.5 m and weighs 1500 kg, the backward acceleration due to air resistance after falling for 2.5 seconds is 0 in the conventional device. It was .07G. To offset this acceleration, by storing 105 kg of water in the counterweight and releasing it over 2.5 seconds, the acceleration at the beginning of the fall is made equal to the acceleration 2.5 seconds later. did it.

Assuming there is no air resistance, the reason why the acceleration of the test specimen can be increased by reducing the mass of the counterweight can be expressed mathematically as follows.

The coordinate axes are set along the wire rope, and the direction in which the test specimen 15 falls is set as positive. The coordinate is X. Further, the gravitational acceleration is g, the mass of the test object is M, the mass of the counterweight is m, and the mass of the wire rope is ignored. At this time, the gravity applied to the test specimen is Mg in the positive direction, and the gravity applied to the counterweight is mg in the negative direction. Also, since the test specimen and counterweight are connected by a wire rope and move as one, the inertia force is (M-!-m)d2
x/dt2. Therefore, the equation of motion becomes. Therefore, the acceleration of the test object and the counterweight combined is d"xM-m.

Therefore, when the mass m of the counterweight decreases, the acceleration d2x/dt'' of the test object and the counterweight combined increases.

As detailed above, in the apparatus of this example, the action of the counterweight that drains water prevents unintended changes in test conditions, and the microgravity applied to the test object in the test body is controlled in a constant or predetermined pattern. can be generated along.

〔Effect of the invention〕

In the drop tower type microgravity test apparatus of the present invention, a counterweight is constructed from a container having a liquid discharge hole at the bottom and the liquid stored in the container, and the liquid is discharged from the liquid discharge hole while the test specimen is falling. Since the liquid in the container is discharged, microgravity applied to the test object in the test body can be generated in a constant or predetermined pattern.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional drop tower type microgravity testing apparatus. DESCRIPTION OF SYMBOLS 1...Test base, 2...Sand for braking, 3...Fixing part, 4...Hanging device, 5...Electromagnet, 6...Test box, 7...Adsorption plate, 8...Lance-shaped brake rod, 9...Control equipment, 10...
Battery, 11... Telemeter, 12... Video camera, 13... Fuel tank model, 14... Liquid fuel, 1
5... Test specimen (total of those labeled 6 to 14),
16...pulley, 17...pulley, 18...
Wire rope, 19... Counterweight, 20... Counterweight, 21... Container, 22... Drain hole, 23... Water. Agent Patent attorney Akira Sakama and 2 other PJ1 Sen

Claims (1)

[Claims] A test specimen equipped with a test object and an observation device inside is connected to a counterweight via a wire rope, and the test specimen and counterweight are suspended via the wire rope by a pulley provided above, In a drop tower type microgravity test device that performs a microgravity test by dropping a test specimen, the counterweight is made up of a container with a liquid discharge hole at the bottom and the liquid stored in the container, and the counterweight is configured to prevent the test specimen from falling. A drop tower type microgravity testing device characterized by discharging the liquid in the container from the liquid discharge hole inside the container.