At 12:37 pm today (December 22), the Long March 8 carrier rocket was ignited and launched from the Wenchang Space Launch Site, successfully sending five experimental satellites into their designated orbits. The launch was a complete success, adding a new member to China's Long March series of carrier rockets! This launch is also the final battle of China's new generation carrier rocket launch mission during the 13th Five Year Plan period.

Focus on commercial space launchesFill the gap of 3-4.5 tons in solar synchronous orbitThe Long March 8 carrier rocket is a new generation of medium-sized carrier rocket developed by China for the international commercial space launch market. At present, the demand for launching low - and medium orbit satellites is increasingly strong, and China lacks suitable launch vehicles for launching 3-4.5 ton sun synchronous orbit satellites. Therefore, the Long March 8 rocket has emerged. It adopts a core stage bundled with two boosters configuration, with a total length of about 50.3 meters, a takeoff mass of about 356 tons, a takeoff thrust of about 480 tons, and a maximum capacity of over 4.5 tons to be sent into a 700 kilometer sun synchronous orbit; If two boosters are omitted, the carrying capacity of the same orbit can reach 3 tons. As a new generation carrier rocket, the Chang-8 rocket uses green and environmentally friendly liquid propellants.The Chang-8 rocket is a cost-effective, easy-to-use, and safe rocket that will become a driving force and main force in the domestic and international commercial space launch market, "said Wu Yitian, Deputy Chief Engineer of the Chang-8 rocketInnovative development modeBuild 'Fast Eight' with One Arrow in Three Years

The Chang-8 rocket follows the development concept of "modularization, serialization, and combination". Its first stage and booster draw inspiration from the core first stage and booster of the Long March 7 rocket, while its second stage draws inspiration from the third stage of the Long March 3 rocket.Deputy Commander in Chief of Chang-8 Rocket, Bao Cheng, said that from project initiation to development and subsequent tasks, Chang-8 Rocket highlights a "fast" approach. 'Fast' is mainly reflected in three aspects: fast development speed, fast fulfillment capability, and fast launch cycle. The Chang-8 rocket was approved in May 2017 and made its maiden flight this year, taking only three years. For a new type of rocket, this speed is very fast, "Duan Baocheng said." The client has requested a mission, and within a year, we can provide launch services. Among current rockets, this speed is also among the top. "Finally, the launch cycle of the Chang-8 rocket is fast, and" in the future, the launch cycle of the Chang-8 rocket will be shortened to 10 daysThree major technological breakthroughs, pioneering and laying the foundationThe Chang-8 rocket is designed by combining existing modules of active rockets, pioneering the reverse design of rockets in China. The development team has innovated multiple technologies, especially the "three major breakthroughs", providing further technical support for China's future rocket development.All along, China's newly developed rockets have undergone full rocket modal tests to obtain the dynamic characteristic parameters of the rocket during flight through physical experiments. The Chang-8 rocket is the first medium to large rocket developed in China that has not undergone full rocket modal testing. Xiao Yun, the commander-in-chief of the Chang-8 rocket, said, "We have solved the problem of obtaining characteristic frequencies, vibration modes, and other data of the rocket body through modal synthesis technology that combines virtual and real simulationHow to ensure product reliability without conducting full arrow modal testing? According to Song Zhengyu, the chief engineer of Changba Rocket, we have adopted a series of innovative methods to make the model more refined and accurate through independent calculations and comparisons by different teams; At the same time, the deviation of model parameters provided for control system design has further increased. Simply put, the model is more accurate, but the deviation is more severe, and the margin in between is the design margin and reliability. Through these measures, we have significantly reduced technological risks.The breakthrough of modal synthesis technology is of great significance to China's rocket development. Someone once asked, 'Do we need to build a vibration tower the size of a rocket we build?' Song Zhengyu said that as a new type of rocket, the Chang-8 rocket did not have a dedicated vibration tower built, nor did it produce samples for physical vibration tests. Instead, it truly utilized modal synthesis technology, which has accumulated valuable experience for improving efficiency and saving costs in the future development of new rocket models in China.Breakthrough 2: Actively identifying system interference, it is the first rocket in China to apply active anti-jamming and load shedding technology.The Chang-8 rocket exhibits the characteristics of a "big head, thin neck" in terms of structural features, with a large fairing and relatively weak structural strength of the rocket's second stage body. Hu Haifeng, Deputy Chief Engineer of the Chang-8 Rocket Control System, introduced that the "static instability coefficient" of this rocket is more than three times that of China's active rockets, making it more sensitive to system interference. If these interferences cannot be eliminated in a timely manner, it will cause damage to the secondary rocket structure. Xiao Yun said that it's like driving a car, where the crosswind can easily overturn the car. At this point, it's necessary to adjust the front of the car to face the direction of the wind.For this purpose, the development team adopted self disturbance rejection and active load shedding technology. The greater the static instability, the greater the angular velocity of the arrow's movement around the center under wind interference. The designers cleverly utilized this feature by identifying and compensating for interference torque through self disturbance rejection technology, achieving significant results.Song Zhengyu said that the successful launch of the Chang-8 rocket has solved the adaptability problem of thin-walled structure rockets in various wind conditions in China, providing a guarantee for the lightweight design and application of the structure, and helping to further improve the carrying efficiency.Breakthrough 3: Putting the engine on the throttle is the first rocket in China to apply engine throttling technology.The so-called throttling, Xiao Yun has a vivid explanation, is to put the throttle on the engine. In the past, after the engine was ignited, it maintained a constant thrust and flew upwards; Now when the rocket flies into a windy area, we retract the throttle and slow down the rocket's flight speed. The reason for doing this is because the speed of the first stage flight of the Chang-8 rocket is fast, which greatly increases the dynamic pressure borne by the rocket structure in windy areas. Song Zhengyu introduced that the dynamic pressure of the Chang-8 rocket must be reduced by half to meet the requirements of the flight profile. For this reason, the Chang-8 rocket adopted engine throttling technology for the first time in the first stage flight phase, which laid the foundation for the subsequent reuse and release of China's carrier rockets.

The breakthrough of CCTV Network modal synthesis technology is of great significance to China's rocket development. Someone once asked, 'Do we need to build a vibration tower the size of a rocket we build?' Song Zhengyu said that as a new type of rocket, the Chang-8 rocket did not have a dedicated vibration tower built, nor did it produce samples for physical vibration tests. Instead, it truly utilized modal synthesis technology, which has accumulated valuable experience for improving efficiency and saving costs in the future development of new rocket models in China. Breakthrough 2: Actively identifying system interference, it is the first rocket in China to apply active anti-jamming and load shedding technology. The Chang-8 rocket exhibits the characteristics of a "big head, thin neck" in terms of structural features, with a large fairing and relatively weak structural strength of the rocket's second stage body. Hu Haifeng, Deputy Chief Engineer of the Chang-8 Rocket Control System, introduced that the "static instability coefficient" of this rocket is more than three times that of China's active rockets, making it more sensitive to system interference. If these interferences cannot be eliminated in a timely manner, it will cause damage to the secondary rocket structure. Xiao Yun said that it's like driving a car, where the crosswind can easily overturn the car. At this point, it's necessary to adjust the front of the car to face the direction of the wind. For this purpose, the development team adopted self disturbance rejection and active load shedding technology. The greater the static instability, the greater the angular velocity of the arrow's movement around the center under wind interference. The designers cleverly utilized this feature by identifying and compensating for interference torque through self disturbance rejection technology, achieving significant results. Song Zhengyu said that the successful launch of the Chang-8 rocket has solved the adaptability problem of thin-walled structure rockets in various wind conditions in China, providing a guarantee for the lightweight design and application of the structure, and helping to further improve the carrying efficiency.

Breakthrough 3: Putting the engine on the throttle is the first rocket in China to apply engine throttling technology. The so-called throttling, Xiao Yun has a vivid explanation, is to put the throttle on the engine. In the past, after the engine was ignited, it maintained a constant thrust and flew upwards; Now when the rocket flies into a windy area, we retract the throttle and slow down the rocket's flight speed. The reason for doing this is because the speed of the first stage flight of the Chang-8 rocket is fast, which greatly increases the dynamic pressure borne by the rocket structure in windy areas. Song Zhengyu introduced that the dynamic pressure of the Chang-8 rocket must be reduced by half to meet the requirements of the flight profile. For this reason, the Chang-8 rocket adopted engine throttling technology for the first time in the first stage flight phase, which laid the foundation for the subsequent reuse and release of China's carrier rockets.