Source: China News Network
Wenchang, 20 Sep (Xinhua) -- On 20 September, the Long March 7 Yaosi carrier rocket (hereinafter referred to as the "Changqi" rocket) carried the Tianzhou-3 cargo spacecraft into space at the Wenchang Cosmodrome in China, successfully sending it into the predetermined orbit, and the "Tiangong" welcomed new visitors.
Astronauts have to stay on the space station for a long time, eat, wear, use and even breathe the materials needed, and the fuel needed to maintain the correct orbit of the space station must be transported by cargo ships. In order to ensure the safety of "Space Express" in the transportation process, the developers of the First Academy of China Aerospace Science and Technology Group specially built the rocket into a heat-proof, rain-proof and wind-proof "freight car".
The Tianzhou-3 cargo spacecraft ignited and took off in Wenchang. Photo by Hu Xujie
It is reported that the Long March 7 carrier rocket is a new generation of medium-sized carrier rockets with high reliability and high safety developed to meet the needs of China's manned space station project launch cargo spacecraft and the long-term needs of future manned carrier rocket upgrading.
"Cardigan"-style "heat-proof clothing"
During the rocket flight, the core stage engine will spew out a huge flame, at this time, the rear transition section of the booster must withstand the strong heat flow of the flame rewind, and its thermal protection design will cause structural ablation if it is not enough, and over-design will affect the carrying capacity of the rocket. Designers innovated the application and installation of heat-proof materials, and put special heat-proof felts like "cardigans" on the rocket booster, which not only weighed less, but also had higher heat protection efficiency.
According to Yao Ruijuan, structural designer of the Zhengqi Yaosi carrier rocket of the first president of the Aerospace Science and Technology Group, if the traditional method is used, the heat-proof coating is sprayed in the transition section after the booster, and the production cycle is long. As a result, the designers innovated the idea of changing the heat-proof suit from "spraying" on the surface of the post-transition section to "draping" on the body.
The designers used high-temperature resistant materials to make a piece of flexible heat-resistant felt for the booster. It has "inside", "surface", and sandwich, starting from the side close to the core level, starting from the side close to the core level, and opening on the outside away from the core level, like a "cardigan" wrapped in the booster, so that the rear transition section is protected from the fire "baking" test.
Yao Ruijuan pointed out that the traditional heat-proof method is used to spray the heat-proof coating on the booster as a whole, and the weight is between 70 kg and 100 kg, while the new heat-proof felt weighs only about 20 kg, the weight is reduced by about 75%, and the heat-proof effect is better. 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 new generation of launch vehicle launch sites has a humid climate and heavy precipitation, with moderate rainfall of 5 to 15 mm in 12 hours a year. Active rocket launch selection windows will avoid thunderstorm days, while the "Long Seven" rocket can achieve medium rain launches, which is because the new generation of carrier rockets has made a "waterproof" design.
In fact, rocket waterproofing is not only rainproof. People who have seen the rocket launch have seen the rocket after the refueling, affected by the low temperature propellant, the temperature on the surface of the arrow body is low, and the condensed water flows down the arrow body like rain, which is also the water that the rocket wants to prevent. In addition, the condensed water on the arrow wall and pipeline may also freeze, and the ice will melt and form frost melting water.
How is a 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 by a single machine, not solved in the system, what can be solved in the system, not in the overall solution", and solve the waterproof problem from the "source of the product".
At the beginning of the design of the new generation of launch vehicles, the waterproof function was achieved as much as possible through structural design. Lu Songtao said that the "Changqi" rocket only has more than a thousand waterproof parts of the electrical connector, which does not include the cable body, cable import and export, instrument body, instrument and structure gap and overall professional waterproofing, the waterproof workload is evident.
Withstands class 8 winds
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 Zhengqi carrier rocket, the first president of the Aerospace Science and Technology Group, said, "In order to improve the ability to resist wind, we have installed the 'Windproof Load Reduction Device' on the 'Changqi' rocket, so that even if it encounters the weather of the 8th level of high winds, the 'Changqi' rocket can still be transferred." ”
In general, the largest wind level on land is 9, and in meteorology, winds above 8 level reach the "gale" level. From August to November each year, the Wenchang Launch Site in Hainan is affected by strong tropical storms and typhoons, and due to the proximity to the sea, the wind speed increases with the increase of altitude from the ground.
Cheng Tangming said that the wind speed at a height of fifty or sixty meters above the ground at the Wenchang launch site is much higher than the ground wind speed, and we call this wind that changes with the height from the ground "shallow wind". "The ground feels a breeze, and the place at the rocket level may be 'strong wind'."
To this end, the "Long Seven" rocket model team has appropriately strengthened the local structure of the rocket and designed a "windproof load reduction device" for the rocket. This device adopts a stretchable truss structure, one end is fixed to the umbilical tower of the active launch platform, and the other end is docked with the rocket secondary engine frame joint after unfolding, so that in the vertical transition process, the rocket is connected to the umbilical tower, which can significantly reduce the wind load of the rocket.
With the "windproof load reduction device", the "Long Seven" rocket is not afraid of the "windy" weather and can be transferred around the clock. (End)