China News Service, Beijing, June 15 (Guo Chaokai, Qian Hang) The last satellite launch window of China Beidou No. 3 Global Satellite Navigation System is scheduled to be on June 16 from 10:11 to 10:50. emission. The satellite is a geostationary satellite, and will be launched by the Long March 3B rocket.

　　The Long March 3B rocket is the largest rocket in the Long Top 3 rocket series. The reporter interviewed relevant experts to reveal the long top three series rockets known as the "Beidou Train".

Gold Rocket

　　The Changjia Series A rocket consists of the Long March 3A, Long March 3B, and Long March 3C Type 3 liquid carrier rockets. Since the launch of the first Beidou satellite in 2007, in the past 13 years, the Changbaijia series rockets have sent all Beidou satellites into a predetermined orbit, with a launch success rate of 100%. It can be said that the long top three series rocket is accompanied by every step of the construction and development of the Beidou system and is a veritable "Beidou Special Train".

　　At present, China has developed more than a dozen Long March series rockets. Among them, only the Long March II F rocket type 1 rocket is known as the "Shenjian"; the "Gold Medal Rocket" has six types, and the Changjia Series Rocket is one of them.

　　According to international practice, a rocket with a success rate of more than 95% can be called a "gold rocket". The Long March 2C rocket reached this standard as early as 1998, and was awarded the "Gold Medal of the High Quality Long March 2C Carrier Rocket" by China Aerospace Industry Corporation, the first "Gold Medal Rocket" in China.

　　After the Long March 2C rocket, in 2007, the Long March 3A rocket was awarded the "Gold Rocket" title by China Aerospace Science and Technology Corporation. The Long March 3A rocket is mainly used to launch geosynchronous transfer orbit satellites. It is China's main rocket, and its launch success rate is ahead of similar rockets in various countries in the world.

Three Brothers

　　As early as the early stage of development, the development team of the Changjiajia series rockets took the Long March 3A, Changzheng 3B, and Changzheng 3C rockets as a series of rockets to modularize, combine, and optimize the design. The Long March 3A rocket is the basic development model.

　　The Long March 3A rocket is a large three-stage cryogenic liquid rocket formed by redesigning the third stage on the basis of the Long March 3 rocket. It has a total length of 52.52 meters and a geosynchronous transfer orbit (GTO) carrying capacity of 2600 kg.

　　The Long March 3 B rocket was derived by bundling four 2.25 meters of boosters at the core level of the Long March 3 A rocket. This type has a total length of 56.5 meters and a GTO carrying capacity of 5500 kg. In addition, the researchers also bundled two 2.25 meter boosters on the basis of the Long March 3 A rocket to form a Long March 3 C rocket with a GTO carrying capacity of up to 3900 kg.

　　The development model of Changjiajia series rockets is implemented in accordance with the technical approach of “upper and lower bundles, first modification and later bundles”, which reflects the advanced design concepts such as modularization, combination and overall optimization. This development idea played an important role in guiding the formation of Changjia and its development rockets and the development planning of large rockets.

　　Jiang Jie, chief designer of the Changjiajia series rocket of the China Academy of Launch Vehicle Technology affiliated to China Aerospace Science and Technology Group, said that the Changjiajia series rocket can be launched with one arrow or multiple arrows; it can also be used for standard geosynchronous transfer orbit launch , Can also be used for super-synchronous transfer orbit or low-inclination synchronous transfer orbit launch and deep-space detector launch, and can also achieve lateral maneuvering, multiple spins, derotation, orientation, etc. during flight to meet the satellite Various user requirements.

Two propellants

　　Jiang Jie said that the booster, the first substage and the second substage of the Changjiajia series rocket all use the conventional propellant combination of nitrous oxide + unsymmetrical dimethylhydrazine, and the third substage uses low temperature propulsion of liquid oxygen + liquid hydrogen剂组合。 Agent combination.

　　For liquid rockets, liquid propellants have risks such as volatility and corrosion. Therefore, they must be launched within a certain period of time before refueling is completed before launch. Taking the room temperature propellant nitrous oxide and unsymmetrical dimethylhydrazine as examples, their storage period is about 7 days after filling; while the storage period of low temperature propellant liquid hydrogen and liquid oxygen is only 1 day.

　　On June 16, the Long March 3B rocket will lift the last satellite of the Beidou-3 global satellite navigation system into the sky. For this type of rocket, low-temperature fuel refueling is expected to start 7 hours before launch and complete 4 and a half minutes before launch.

　　Ceng Zheng, the chief commander of the Changjiajia series rockets of the China Academy of Launch Vehicle Technology, said that the launching accuracy of the Changjiajia series rockets is high and the adaptability is high. The launching accuracy of its launch satellites is comparable to that of world-renowned rockets such as Arian and Universe. Its carrying capacity can cover the quality of most of the world’s applied satellites, which not only significantly enhances the competitiveness of Chinese rockets in the international commercial satellite launch service market, but also creates good conditions for the future development of China’s space industry. (Finish)

The exciting moment of the launch of the Beidou satellite by the Changjiajia rocket. Source: China Academy of Launch Vehicle Technology