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Is the pot too big to brush? Chinese Sky Eye FAST 氦 balloon spiders debut!

via:博客园     time:2019/9/3 18:01:32     readed:199

China Sky Eye FAST has added a beautiful landscape! The hemospherical spider man began to walk freely on the telescope's cauldron (reflecting surface).

Is this helium balloon spider a beggar? In fact, FAST staff (Spiderman) carries a helium balloon, and the weight of the balloon is reduced to only about one-sixth of the original weight, which is the weight that the telescope's reflective surface structure can withstand. The Spider-Man walks in such a gravity environment similar to the surface of the moon, just like the American Apollo moon astronaut, full of fun and novel experiences. Of course, the main purpose of FAST staff walking on the pot surface is to efficiently inspect and maintain the FAST reflective surface.



Spider man walking on reflective surface

The FAST full name is a 500-meter spherical radio telescope with a reflecting surface of 500 m and a spherical radius of 300 m, which is equivalent to 35 standard football fields. In order to leave space for the motor vehicle to pass through the spiral mountain road below the reflecting surface, the reflecting surface is more than 4 meters above the ground, and the edge is up to 50 meters due to the topography.

Its upper surface is a perforated aluminum panel with a thickness of only 2mm. Under the aluminum panel are thousands of reflective surface unit back frames, cable nets, node plates and other ancillary structures/mechanical components. Under normal circumstances, it cannot withstand The weight of a staff member. Such a spherical cauldron containing thousands of parts, how to achieve daily inspection and maintenance work is a big problem!

Field conditions such as the span of 500 meters, the height difference of 50 meters and the curved angle of the edge of nearly 60 degrees make it difficult for the staff to check and maintain the large-eyed cauldron, which is enough to reject the existing crane equipment. Outside the door (the boom of a conventional crane is difficult to cover or take into account such a large range of curved surfaces). If you use a small mobile robot instead of manual work, and do not say the complexity of the homework, once you break down, you have to find a way to get it out, so the balloon spiders are coming out.

It is a good idea to fly several helium balloon spiders in this large pot. You can work on different areas of the cauldron at the same time. Spider-Man can be competent for all kinds of complicated operations and is very reliable after solving safety problems.


Helium balloon leap reflection ring beam

So how do the balloon spiders walk in the big pot? We know that Apollo astronauts have adopted a kangaroo-style approach to the moon, because it is easier to control the balance by jumping forward in a microgravity environment than walking across a walk. Surprisingly, our helium balloon spiders used a crawling posture. It does not seem to conform to the normal upright habits of the human body, but the center of gravity is more stable, and it is convenient for the staff to inspect and maintain the parts close to the pot.

Under the traction of the helium balloon buoyancy, it is very difficult for people to kneel down in an upright position, so they changed to crawling mode at the beginning. In order to prevent the local pressure from being too large to damage the pot surface, the staff's palm, elbow, knee joint and toe are wearing a cushion with an enlarged contact area. When the dip angle is large, we reduce the net weight of the hemospherical spider man. The spider man climbs the gap between the reflective panels and climbs easily to the height that is difficult to reach under normal gravity.

So how do the hemispherical spiders enter and exit the cauldron across a height of 50 meters? Quite simply, by increasing or decreasing the weight of the device, we can adjust the hemispherical spiders to micro-buoyancy or micro-gravity mode, and they can flick through the obstacles of 50 meters and fly in or out of the cauldron.


Helium balloon spider man ready to fly

Some people may ask, what if there is wind in the case of microgravity? Will it blow away? Indeed, this is the biggest problem facing the ballooning spiders. Fortunately, there are exactly 23 evenly spaced measuring foundations with prominent reflecting surfaces in the cauldron. Pulling at least 3 traction ropes from the spiderman to the three foundation piers constitutes a clever safety aid system.

In the high wind environment, the three traction ropes are tensioned to help the spiderman to fix on the surface of the pot, waiting for the wind to pass, and continue to work; in the windy or windless environment, the three traction ropes are slack, and the spiders rely on their own crawling or Climbing free to walk. Fortunately, the Guizhou area where FAST is located is a calm wind environment with very few windy weather, which is conducive to the walking and homework of the ballooning spiders.


Spiderman climbs to the edge of the reflective surface

Helium is a very safe inert gas with high buoyancy. Some people may ask, what if the suffocation in the balloon leaks? First of all, the balloon material is a special high-strength composite fiber material that is leak-proof and tear-proof, and has experience in using a variety of airships such as airships. Secondly, the balloon itself has a gas pressure adjusting device, which is not caused by exposure. High temperatures cause excessive pressure to cause the balloon to burst.

The success of the FAST field test marks the feasibility of a completely innovative new device such as the Helium Balloon Spiderman. The next step is to continuously improve the new product from various details, depending on the results of the test, until the finalization, Production and procurement. In the near future, the big country heavyweight FAST will have a blessing of this device and will run safer and more stable. What's even more amazing is that people who come to FAST to visit or work and study will have the privilege of witnessing the wonders of “small balls in the cauldron”, adding a brilliant color to the Chinese eye.

About the Author

Li Hui: Associate Research Fellow, National Astronomical Observatories, Chinese Academy of Sciences. He is mainly engaged in R&D and operation debugging of FAST telescope. He has served as the deputy chief engineer of FAST feed support system and the leader of structural and engineering mechanics of FAST commissioning group.

Jiang Peng: Researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, doctoral tutor, FAST chief engineer.

Editor-in-Chief: Liu Chao (National Observatory Researcher)

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