China News Service, Wenchang, September 20 (Ma Shuaisha, Guo Chaokai, Dong Jiaying) On September 20, the Long March 7 Yaosi carrier rocket (hereinafter referred to as the "Changqi" rocket) lifted the Tianzhou-3 cargo at the Wenchang Space Launch Site in China The spacecraft drove into space and successfully sent it into a predetermined orbit. The "Tiangong" welcomed new visitors.

　　Astronauts have to stay in the space station for a long time, and the materials needed to eat, wear, use and even breathe. The fuel needed for the space station to maintain the correct orbit must be transported by cargo spacecraft.

In order to ensure the safety of the "space express" in the transportation process, the developers of the First Academy of China Aerospace Science and Technology Corporation have specially built the rocket into a heat-proof, rain-proof, and wind-proof "cargo truck".

The Tianzhou-3 cargo spacecraft took off in Wenchang.

Photo by Hu Xujie

　　It is reported that the Long March 7 launch vehicle is a new generation of highly reliable and safe medium-sized launch vehicle developed to meet the needs of China's manned space station project to launch cargo spacecraft and the long-term needs of future manned launch vehicle replacement.

"Cardigan" style "heat protection suit"

　　During the rocket flight, the core-stage engine will emit a huge flame. At this time, the transition section of the booster has to withstand the strong heat flow of the flame rewinding. If the thermal protection design is not enough, it will cause structural ablation and over-design. It will also affect the carrying capacity of the rocket.

The designers innovated the application and installation methods of heat-proof materials, and put a special heat-proof felt like a "cardigan" on the rocket booster, which not only has a lighter weight, but also has higher heat-proof efficiency.

　　According to Yao Ruijuan, the structural designer of the Long March 7 Yao 4 launch vehicle of the First Academy of the Aerospace Science and Technology Group, if the traditional method is used, the heat-resistant coating is sprayed in the transition section of the booster, and the production cycle is longer.

As a result, the designers innovated their ideas and changed the heat-resistant clothing from "spraying" on the surface of the rear transition section to "clothing" on the body.

　　The designer used high-temperature resistant materials to make a flexible heat-proof felt for the booster.

It has a "in", a "face", and a sandwich. It starts to "drape" from the side close to the core stage, and opens on the outer side away from the core stage. The transition section is protected from the fire "roasting" inspection.

　　Yao Ruijuan pointed out that the traditional heat protection method is used to spray a heat protection coating on the booster. The weight is between 70 kg and 100 kg, while the weight of the new heat protection felt is only about 20 kg, which is about 75% lighter. The heat protection effect is better.

The flexible heat-proof felt has been successfully applied on the Changqi rocket, and will be promoted to other models in the future.

Special "raincoat" structure waterproof

　　The launch site of the new generation of carrier rockets has a humid climate and heavy rainfall. There are more moderate rains of 5 to 15 mm in 12 hours throughout the year.

Active rockets will avoid thunderstorms when launching the selection window, while the "Changqi" rocket can achieve moderate rain launches, because the new generation of launch vehicles has a "waterproof" design.

　　In fact, the rocket waterproof is more than just rainproof.

Anyone who has seen a rocket launch has seen a rocket after refueling. Affected by the low-temperature propellant, the temperature on the surface of the rocket body is low, and the condensation water flows down the rocket body like rain. This is also the water that the rocket must guard against.

In addition, the condensed water on the arrow walls and pipelines may freeze, and the melting of ice will form frost melted water.

　　How is the rocket waterproof?

Lu Songtao, a designer of the General Department of the First Academy of Aerospace Science and Technology Group, said that in the waterproof design, we follow the principle of “what can be solved in a single machine, not in the system, and what can be solved in the system, not in the overall” principle, and solve the waterproof problem from the “product source”. problem.

　　At the beginning of the design of the new generation of launch vehicles, the waterproof function was achieved through structural design as much as possible.

According to Lu Songtao, the "Changqi" rocket only has more than a thousand waterproof parts of the electrical connector, which does not include the cable body, the cable inlet and outlet, the instrument body, the gap between the instrument and the structure, and the overall professional waterproofing of the structure. It is obvious.

Can be worth 8 wind

　　There is a "shallow wind" at the Wenchang launch site in Hainan, which brings challenges to the vertical transition of the "Changqi" rocket.

Cheng Tangming, chief designer of the Long March 7 launch vehicle of the First Academy of the Aerospace Science and Technology Group, said, “In order to improve wind resistance, we have installed a'wind-proof and load-reducing device' for the'Changqi' rocket. In the weather, the'Chang Seven' rocket can still transition."

　　Under normal circumstances, the largest wind level on land is level 9, and in meteorology, winds above level 8 reach the "gale" level.

From August to November each year, the Hainan Wenchang launch site will be affected by strong tropical storms and typhoons. Due to the sea, the wind speed increases as the height above the ground increases.

　　Cheng Tangming said that the wind speed at the Wenchang launch site at a height of 50 or 60 meters above the ground is much higher than that at the ground. We call this type of wind that varies with the height above the ground as "shallow wind."

"What is felt on the ground is a breeze, and it may be a'gale' at the first stage of the rocket."

　　To this end, the "Changqi" rocket model team has appropriately strengthened the local structure of the rocket and designed a "wind-proof load reduction device" for the rocket.

This device adopts a stretchable truss structure, one end is fixed on the umbilical tower of the movable launch platform, and after unfolding, the other end is docked with the rocket's secondary engine frame joint, so that the rocket and the umbilical tower are connected during the vertical transition. , Can significantly reduce the wind load on the rocket.

　　With the "wind-proof and load-reducing device", the "Changqi" rocket is not afraid of "high wind" weather and can be transferred around the clock. (over)