At 20:11 on February 22, 2025, the Long March 3B carrier rocket carrying the ChinaSat 10R satellite was successfully launched from the Xichang Satellite Launch Center. Subsequently, the satellite successfully entered the predetermined orbit, and the launch mission was a complete success.<\/p>\n
The following is the relevant research and analysis content of the Long March 3B launch vehicle:<\/p>\n
1. Basic information<\/p>\n
The Long March 3B carrier rocket was developed by the First Academy of Aerospace Science and Technology and was first launched on February 15, 1996. It is mainly used to launch heavy-duty satellites in geostationary transfer orbits, light satellites with one rocket and multiple satellites, and Beidou navigation satellites. The Long March 3B launch vehicle is a three-stage semi-configuration with a height of 56.3 meters. The sun-synchronous orbit (700 km) has a transport capacity of more than 4.5 tons (CZ-3B\/E G5), the synchronous transfer orbit has a transport capacity of more than 5.55 tons (CZ-3B\/E G2), and the earth-moon transfer orbit has a transport capacity of more than 3.78 tons (CZ-3B\/E G2).<\/p>\n
2. Rocket composition<\/p>\n
(1) One sub-level<\/p>\n
The first stage of the Long March 3B launch vehicle has a diameter of 3.35 meters and a length of 23.27 meters (excluding the interstage section). It is equipped with a set of YF-21C engines. The YF-21C is composed of four YF-20Cs connected in parallel, with a thrust of 305.3 tons at sea level and a specific impulse of 261 seconds. YF-20C is an improved version of YF-20B, and YF-20B is an improved version of YF-20. It mainly improves the thrust chamber head injector, body structure, number of turbine nozzles, gas generator, and gunpowder starter grain. YF-20 is a 70-ton normal-temperature engine. The fuel is dimethylhydrazine\/dinitrogen tetroxide and uses a pump-type delivery system.<\/p>\n
(2) Second level<\/p>\n
The second stage of the Long March 3B launch vehicle has a diameter of 3.35 meters and a length of 12.92 meters. The main engine of the second stage is a YF-22E. The YF-22E is the latest deeply improved model of the YF-22 series. It uses unbiased dimethylhydrazine\/nitrogen tetroxide as propellant, uses an extended vacuum nozzle, and the fuel circulation method is a gas generator cycle. The vacuum thrust is 742.04 kN, and the vacuum specific impulse is 303 s. The second stage of the Long March 3B launch vehicle is also equipped with a travel engine. The travel engine is a YF-23C engine. The YF-23C is an improved version of the YF-23B, which increases the specific impulse. It also uses dinitrogen tetroxide\/uniform dimethylhydrazine as propellant, with a vacuum thrust of 4\u00d711.8 kN and a vacuum specific impulse of 289 s.<\/p>\n
(3) Third sub-level<\/p>\n
The third stage of the Long March 3B launch vehicle is 3 meters in diameter and 12.375 meters long, and is equipped with a YF-75 engine. YF-75 is composed of two independently working single machines in parallel. The propellants are liquid oxygen and liquid hydrogen. It adopts a gas generator circulation and pump pressure supply system. The YF-75 single unit has a vacuum thrust of 83.5 kN and a vacuum specific impulse of 438 s. As my country’s second-generation upper-stage liquid hydrogen and liquid oxygen rocket engine, YF-75 has obvious shortcomings. Due to its simple circulation method, the thrust and specific impulse of the engine are relatively small.<\/p>\n
(4) Booster<\/p>\n
The Long March 3B launch vehicle is equipped with four boosters. Each booster has a diameter of 2.25 meters and a length of 16.094 meters. It is equipped with a YF-25 engine. The YF-25 is improved from the YF-20C, which is an improved version of the YF-20B. YF-25 uses dinitrogen tetroxide\/uniform dimethylhydrazine as propellant, with a thrust of 748 kN at sea level and a specific impulse of 261 s.<\/p>\n
3. Rocket spectrum<\/p>\n
The Long March 3B launch vehicle is divided into standard type and enhanced type. The standard version includes the Long March 3B standard version (CZ-3B) and the Long March 3B modified version 1 (CZ-3B\/G1). Currently, all standard models have been discontinued. In order to improve the GTO’s carrying capacity, an enhanced version was developed based on the standard version, and the core stage and booster were lengthened, including the Long March 3B modified to the second type (CZ-3B\/G2), the Long March 3B modified to the third type (CZ-3B\/G3), the Long March 3B modified to the 3Z type\/Yuanzheng 1 (CZ-3B\/YZ-1) and the Long March 3B modified to the fifth type (CZ-3B\/G5).<\/p>\n
(1) Long March 3B modified type 2 (CZ-3B\/G2)<\/p>\n
CZ-3B\/G2 is based on CZ-3B, with the first sub-stage lengthened by 1.488 meters, the boost stage lengthened by 0.768 meters, and the second-stage engine was replaced by YF-22K. The standard GTO transport capacity of CZ-3B\/G2 is 5.55 tons and the TLI transport capacity is 3.78 tons. On May 14, 2007, CZ-3B\/G2 was successfully launched, carrying Nigeria Communications Satellite 1.<\/p>\n
(2) Long March 3 Type B modified to Type 3 (CZ-3B\/G3)<\/p>\n
CZ-3B\/G3 inherits the basic status of CZ-3B\/G2, but the fairing adopts the 4200F type fairing. In addition, CZ-3B\/G3 uses real-time transmission technology of telemetry images to enhance flight reliability. The standard GTO transport capacity of CZ-3B\/G3 is 5.4 tons. At present, as the de-mission work of CZ-3B\/G2 and CZ-3B\/G3 continues, the only difference between CZ-3B\/G3 and CZ-3B\/G2 is the fairing size. On September 19, 2011, CZ-3B\/G3 was successfully launched for the first time, carrying China Star-1A.<\/p>\n
(3) Long March 3B modified to Type 3Z (CZ-3B\/G3Z)<\/p>\n
CZ-3B\/G3Z inherits the basic status of CZ-3B\/G3, but the fairing is replaced with a 4200Z type fairing and uses a 1194A satellite bracket. The CZ-3B\/G3Z has a total length of 57.126 meters and a standard GTO transport capacity of 5.2 tons.<\/p>\n
(4) Long March 3B\/Yuanzheng 1 (CZ-3B\/YZ-1)<\/p>\n
CZ-3B\/YZ-1 is based on CZ-3B\/G3Z and is equipped with a Yuanzheng-1 upper stage. The CZ-3B\/YZ-1 has a MEO transport capacity of 2.2 tons and is mainly used to carry out the Beidou satellite’s “one arrow and two satellites” mission. On July 25, 2015, CZ-3B\/YZ-1 successfully made its first flight, carrying the Beidou-3 MEO-1S\/MEO-2S satellite.<\/p>\n
(5) Long March 3B modified version 5 (CZ-3B\/G5)<\/p>\n
CZ-3B\/G5 is also improved on the basis of CZ-3B\/G3Z. The fairing is replaced with the newly developed 4200ZL fairing, which is lengthened by 900 mm. The satellite bracket is no longer used 1194A, but replaced with 2334A. In addition, the control system is no longer a dual-laser inertial group\/satellite navigation composite guidance, but has become an iterative + perturbation guidance scheme. After improvement and optimization, CZ-3B\/G5 can also perform SSO launch missions, and its SSO (500 km) transport capacity is 4.5 tons. On December 6, 2020, CZ-3B\/G5 successfully made its first flight, carrying the Gaofen-14 satellite.<\/p>\n
4. Rocket Analysis<\/p>\n
(1) The origin of Long March 3B<\/p>\n
In 1978, my country started the development of the Long March 3 launch vehicle. On April 8, 1984, Long March 3 carried my country’s first communications satellite Dongfanghong 2 and was successfully launched into orbit. At this point, our country has become the fourth country in the world with geosynchronous satellite launch capabilities. On April 7, 1990, Long March 3 successfully launched the American Hughes Asia-1 satellite into geosynchronous transfer orbit, and Chinese rockets began to enter the international space launch market. As the mass of geosynchronous satellites increases, our country urgently needs a new rocket to meet the needs of larger mass launch missions. On July 16, 1990, the Long March 2E successfully made its first flight at the Xichang Satellite Launch Center, marking the first breakthrough in booster bundling technology in my country. Drawing on the experience of the Long March 2E, our country also bundled four boosters with the Long March 3 to increase its transport capacity, resulting in the Long March 3B launch vehicle.<\/p>\n
(2) Launch records of Long March 3B<\/p>\n
At present, the Long March 3B carrier rocket has completed 104 launch missions, all of which were carried out at the Xichang Satellite Launch Center. Among them, 2 launch missions failed, 2 launch missions were partially successful, and 100 launch missions were completely successful. The launch success rate is 96.15%. The two failed missions were: the first flight on February 15, 1996, and the launch mission on April 9, 2020. Among them, the failure of the first flight had very serious consequences, with 6 people dead and 57 injured. As a result, my country’s external commercial launch services fell into a trough. The satellite on board at that time was Intelsat 708. The cause of the accident was a change in the inertial reference of the rocket control system. At 19:46 on April 9, 2020, the Long March 3B carrier rocket was launched into space carrying the Palapa N1. Both the first and second stages of the rocket flew normally, but the launch failed due to the failure of an engine igniter in the third stage. In addition, two partially successful launch missions were: the launch mission on August 31, 2009 and the launch mission on June 19, 2017. On August 31, 2009, the Long March 3 was launched into space with the Palapa D. The first and second stages of the rocket flew normally. However, due to a failure of the first subsystem of the third-stage engine, the third-stage engine failed to send the satellite into the scheduled orbit due to insufficient thrust. Instead, it was sent into an orbit lower than the scheduled super-geosynchronous transfer orbit. The launch mission was partially successful. On June 19, 2017, the Long March 3B was launched carrying the ChinaSat 9A communications satellite. Due to an abnormality in the thrusters controlled by the attitude control engine in the third-stage taxiing section of the rocket, the satellite did not enter the intended orbit. Subsequently, the satellite used its own fuel to perform multiple orbit changes and entered the predetermined orbit, but this also caused the satellite’s lifespan to be greatly reduced. It was originally planned to be in orbit for 15 years, but it actually de-orbited after only 4 years.<\/p>\n
(3) The future of Long March 3B<\/p>\n
The advantages of Long March 3B are its high maturity and low launch cost. However, Long March 3B\u2019s first and second stages and booster use toxic propellants, which not only has a low specific impulse, but is also inconsistent with the global trend of using environmentally friendly propellants for rockets. At the same time, with the continuous advent of new generation launch vehicles, they can also undertake the launch tasks required by the Long March 3B. For example, the GTO capacity of the Long March 7A has reached 7 tons, which is much higher than that of the Long March 3B. The advantages of the Long March 3B are being weakened little by little, and it is highly likely that the Long March 3B will be eliminated in the future.<\/p>\n
5. Chatting<\/p>\n
Let me talk about another interesting thing. In 2024, the Xichang Satellite Launch Center completed a total of 19 launch missions, of which 18 were successful and 1 was partially successful. Among these 19 rounds, 8 were from Long March 3B, 5 were from Long March 2C, 2 were from Long March 2D, 2 were from Long March 4B, 1 was from Kuaizhou 1, and 1 was an upgraded version of Kuaizhou 1. Excluding the 2-shot Kuaizhou series solid rockets, in the 17-shot liquid rocket mission, the Long March 3B is a three-stage semi-configuration, and the first and second sub-stages and boosters use dinitrogen tetroxide\/uniform dimethyl hydrazine as propellant; the Long March 2C is a two-stage configuration, and the first and second sub-stages also use dinitrogen tetroxide\/dimethylhydrazine as propellant. Dinitrogen tetroxide\/uniform dimethylhydrazine is used as propellant; Long March 2-D is also a two-stage configuration, and the first and second sub-stages also use dinitrogen tetroxide\/uniform dimethyl hydrazine as propellant; Long March 4B is a three-stage configuration, and the first, second and third stages also use dinitrogen tetroxide\/uniform dimethyl hydrazine as propellant. As the global trend of using environmentally friendly propellants in rockets continues to develop, it will be interesting to see how the Xichang Satellite Launch Center thinks about the current status quo, and then examines the development of an international commercial space port in Sichuan, and then examines the progress of Yangjiang and Xiangshan. In the same way, it will be interesting to examine the Dongfeng Commercial Aerospace Innovation Test Zone.<\/p>\n
The latest masterpiece “Launch Vehicle Industry Chain Map” sorts out the launch vehicle industry chain from four perspectives: structural system, power system, electrical system, and other auxiliary systems. If necessary, you can add micro-consultation.<\/p>\n","protected":false},"excerpt":{"rendered":"
At 20:11 on February 22, 2025, the Long March 3B carrier rocket carrying the ChinaSat 10R satellite was successfully launched from the Xichang Satellite Launch Center. Subsequently, the satellite successfully entered the predetermined orbit, and the launch mission was a complete success. The following is the relevant research and analysis content of the Long March […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[],"class_list":["post-25481","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/25481"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=25481"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/25481\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=25481"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=25481"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=25481"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}