The Long March 5 is currently the largest carrying capacity in China. It successfully made its first flight at the Wenchang Space Launch Site in China on November 3, 2016. However, on July 2, 2017, after the launch of the 18th satellite of the Long March 5th, the rocket flight was abnormal and the launch mission was lost.
Originally, the success of this launch meant that the development of the Long March 5 launch vehicle project was successfully completed and entered the formal application stage. At the same time, it was also the “Fat Five†before the launch of the Lunar 5th lunar probe in the second half of this year. The last practical drill of the Rockets. However, the unexpected launch failure seemed to disrupt the original rhythm.
Previously, China originally planned to use the Long March 5 rocket to launch the first spacecraft “嫦娥五五â€, which was launched by the Long March 5 rocket. In 2018, the world’s first landing and patrol on the back of the moon was launched. The spacecraft that was probed was "Chang'e IV."
The reason for the loss of the Long March 5 remote rocket launch is still under investigation, or will be thoroughly investigated at the end of the year. This defeat will affect the mission plans of China's No. 5 and No. 4 and the space station.
The high success rate of the previous launch was because the Long March rocket was not strong enough.
Since the launch of the 1970 Changzheng No. 1 launch vehicle, the Long March series has clearly become a "big family", achieving the ability to cover from normal temperature to low temperature propulsion, from tandem to bundling, from one arrow to one arrow. High, medium and low orbits can meet the emission requirements of different loads.
The Long March series of launch vehicles carried out 237 launches before the birth of the Long March 5, with a launch success rate of around 97%. Internationally, from 1957 to 2015, the world has launched more than 5,400 times, and the average launch success rate is 91.5%. In this way, the Long March series of rockets have always performed very well, and it has naturally created an illusion: but the launch of the Long March rocket must be successful.
However, such success is based on the fact that the rocket has a small capacity and a relatively old model.
Due to the limitation of China's railway transportation, the maximum diameter of the rocket before the "Five Five" is only 3.35 meters. The maximum capacity of the China Long March series carrier rockets can only reach 5 tons, and the international mainstream level of 12 tons. Compared with the gap, it restricts the development of space technology in China.
"The manned spaceflight project at that time was still in the stage of argumentation. According to the carrying capacity of the rockets in China at that time, it could not meet the needs of the construction of the future space station." Wang Wei, chief commander of the Long March 5 carrier rocket of the Aerospace Science and Technology Group, said that the development of major domestic projects Need to become a direct drive for China to develop large-scale launch vehicles.
In the late 1980s, as the human exploration of the universe continued, the world's major aerospace powers launched a new generation of large-scale launch vehicles, such as Delta 4 and Cosmos 5 in the United States and Arian 5 in Europe. These rockets were adopted. About 5 meters in diameter, a small number, the carrying capacity fully surpassed the rockets of our time.
The purpose of developing a new generation of rockets in various countries is clear: first, to achieve environmental protection through the improvement of clean propellants, and second, to improve carrying capacity and enhance the ability to enter space and commercial competitiveness.
There is a need for major projects, and there are development trends in various countries. It is very urgent to build a "big guy" rocket.
The "difficulties" of the Long March 5 are mainly due to the fact that there are so few "roadblocks":
- The overall technology. To achieve the leap-forward development of the capabilities of launch vehicles, new technologies must be adopted as a whole. Compared with the proportion of new technologies in the development of new rockets of about 30%, the Long March 5 can be said to be another stove. The whole arrow adopts 247 core key new technologies, and the proportion of all new products is more than 90%.
"This high ratio of new technologies means that the amount of development work is increasing, and the difficulty of development is increasing, which means that the risk of development is increasing." Li Dong, chief designer of the Long March 5 rocket, said.
--"heart". The launch vehicle is like the airplane car, and the engine is its "heart." In order to send heavier loads to higher and further places, the rocket not only needs the best engines, but a multi-stage rocket requires different types of engines.
The new generation of rockets must first solve the problem of large thrust. Before that, the single thrust of a single engine in China was only 75 tons, which could not meet the demand of the Long March 5.
The Long March 5 uses a new generation of non-toxic and non-polluting hydrogen and liquid oxygen kerosene engine combination. Eight newly developed 120 tons liquid oxygen kerosene engines are assembled on four boosters, two 50 tons and two. The 9-ton newly developed hydrogen-oxygen engine is assembled on the primary and secondary rockets. In the development process, the biggest problem facing the developers is how to overcome the technology of the large thrust liquid oxygen kerosene engine, which was previously only controlled by Russia.
Some foreign experts even believe that even if we can design it, it is impossible to manufacture it with our existing materials and craftsmanship. However, the Chinese astronauts carried out the day and night research, and in the middle they experienced four engine test failures. They even witnessed the horror of the engine burned in a few seconds, but they still came over, dozens of new materials. More than one hundred new technologies have been overcome. It can be said that "one pound of thrust one inch of gold, 100,000 horsepower 100,000 people!" China became the second country after Russia to fully grasp the high-pressure supplemental combustion engine technology of liquid oxygen kerosene.
- Large structure. Making the rocket bigger and changing the diameter of the arrow from 3.35 meters to 5 meters is not a simple enlargement. To process and manufacture a 5 m arrow structure requires a huge leap in all tooling such as basic machining, tank welding, riveting, and many technical problems that need to be overcome.
The large structure also brought new requirements to the ground test. The previous machine tools, test stations and workshops were unable to meet the large structural requirements of the Long March 5. Therefore, the development of the Long March 5 also led to the new booster separation test. Improvements in technology such as fairing separation test and static test.
The takeoff thrust of the Long March 5 reached 1.5 times that of the largest-scale launch vehicle in active service, and the force of each section of the rocket was complicated. In particular, to solve the problem of rocket booster and core-level transmission force, a single booster not only has to bear nearly 200 tons of core-level self-weight, but also needs to withstand more than 300 tons of offset on a contact surface of less than 0.1 square meters. Concentrated force load, the design difficulty of the program is the most in the history of the development of China's launch vehicle.
Bringing so many technological innovations to the Long March 5 seems to be somewhat risky. As everyone knows, the development of a launch vehicle is a large-scale system project. Any small fault can lead to failure of launch and cause a blow to the aerospace industry.
Chinese astronauts dare to set new goals and have the ability to harness the stages of difficulty and complexity on the road to R&D. They have created a powerful mechanism that miraculously turns dreams into reality like a super-pipeline.
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