Long March 7 isChina Manned Space Projectto the satisfaction ofChina Space StationEngineering launchCargo spaceshipThe predecessor of the new generation medium launch vehicle isLong March II FCarrier rocket.The Long March 7 rocket has a total length of 53 meters, adopts a "two-stage and half" configuration, with a core stage I and core stage II diameter of 3.35 meters, four boosters with a diameter of 2.25 meters, and uses non-toxic and pollution-free fuels such as liquid oxygen and kerosene as propellants. The rocket has a takeoff mass of about 597 tons and a takeoff thrust of 727 tons[94]。Low Earth orbit(LEO) carrying capacity is 14 tons, 700 kilometersSun synchronous orbitThe carrying capacity is about 5.5 tons[1-2][36][60]。
The Long March 7 will gradually replace the Long March 2, Long March 3 and Long March 4 rockets and undertake about 80% of China's space launch missions. It can launch the Tianzhou series cargo spaceships developed by China. When the technology is mature in the future, it will replace the Long March 2F rockets and be used to launch manned spaceships[21][60]。
On June 25, 2016, the Long March 7 carrier rocket launched fromWenchang Space Launch Site, ChinaThe first successful launch is also the first launch mission of Wenchang Space Launch Site[22]。
At 20:25 on August 22, 2024, China successfully launched the Zhongxing 4A satellite by using the Long March 7 modified carrier rocket at Wenchang Space Launch Site. The satellite successfully entered the scheduled orbit, and the launch mission was a complete success.[98][104]
After more than 50 years of development since the 1960s, China's Long March series carrier rockets have experienced the technological process from normal temperature propulsion to low-temperature propulsion, from series to bundling, from single rocket to multiple satellites, from satellite launch to manned spacecraft launch, and gradually developed into a family of multiple models, with the ability to enter low, medium and high orbits,The orbit entry accuracy has reached the international advanced level.However, China's existing Long March series launch vehicles are faced with the problem that their carrying capacity does not meet the needs of long-term development: toxic propellants pose a great environmental hazard in the whole industrial chain, and they have to pay a high price from the production, transportation, storage, use, testing, destruction of propellants to the disposal of residual propellants in the debris, which is not in line with the international trend of green environmental protection;The existing launch sites are all located inland, so it is increasingly difficult to choose the landing area, which is not conducive to opening up and international exchanges and cooperation.In order to meet the needs of China's future space development, China has decided to carry out the development of a new generation of carrier rockets to meet the needs of manned space projects, lunar exploration and other major special work, and to achieve the upgrading of China's carrier rockets[2]。
At the beginning of the 21st century, China needs to launch a large number of spacecraft in various orbits, and the demand for launch vehicles, especially medium-sized launch vehicles, is relatively strong. China has set up projects to develop CZ-5, CZ-6, and CZ-7 launch vehicles.The earliest prototype of the Long March 7 rocket is the Long March 2 F/H type (referred to as the Long March 2 F replacement), that is, the mature technology of the Long March 2 F type is used to replace the newly developed liquid oxygen kerosene engine, that is, the replacement type (H type).At the same time, the Long March 5 series launch vehicles developed were also divided into large, medium and small three types, of which the 3.35 meter diameter medium type and the Long March 2 H type had certain overlap in technology and use.
Finally, the developer decided to develop a new type of medium-sized rocket, which integrates the mature technology of Long March 2F and applies it at the same timeLong March 5With a new number of "Long March 7"[4-5]。
Long March Series Launch Vehicle
Development process
Development principle
Long March No. 7 data
1. Basic type: take the Long March 7, which meets the requirements of the follow-up mission of the manned space project, as the basic type, to demonstrate other configurations of medium-sized rockets.
2. Serialization: based on the basic type, the medium-sized rockets can be serialized by adjusting the number or type of boosters and adding three sub stages of the upper stage.For example, the subsequent models have developed from two and a half stages to three and a half stages (CZ-734 type), and from all coal engines to the upper stage to hydrogen and oxygen (CZ-720-HO type), etc.
3. Inheritance: fully inherit the existing development achievements of the new generation of large launch vehicles and in-service launch vehicles;All liquid engines used in all configurations are based on liquid oxygen kerosene and liquid hydrogen liquid oxygen engines that have been or are being developed in China;The solid booster is based on the solid motor with a thrust of 120 tons under development.For example, Long March 7 inherits the mature technology of CZ-2F, and the liquid oxygen kerosene engine uses the YF-100 engine of the same model as CZ-5 and the YF-115 engine of the same model as CZ-6.
4. Adaptability: the gradient of carrying capacity between the priority configurations is reasonable, basically meeting the launch requirements of different missions of future medium payload.The transportation capacity of Long March 7 ranges from 1 ton to 15 tons, and the tracks cover different tracks such as LEO, SSO, GTO, GEO, etc.
5. Economy: In order to meet a large number of medium capacity launch needs, the developed configuration should meet the economic requirements and strive to reduce launch costs.For example, the propellant of CZ-2 is toxic hydrazine fuel, and the propellant of Long March 7 is non-toxic kerosene, whose price is only one thirtieth of that of the former[4]。
Development team
Design team
Long March 7
Chief designer: Fan Ruixiang[14]
Deputy Chief Designer: Cheng Tangming[31][48]
Deputy Chief Designer: Liu Zhanguo (in charge of power)[14], Fan Hong[32]
Chief designer: Ma Zhonghui[14]
Chief designer of launch platform: Li Dingshi[32]
Designer: Hu Xiaobin, Li Caixia[14]
Management team
Commander in Chief: Wang Xiaojun[14]
Deputy Commander in Chief: Zhang Tao[14]
Chief Commander of Rocket Power System: Deng Xinyu[33]
Development progress
Development process
time
process
Participants
remarks
2010
In March, the information disclosure of a new generation of medium-sized rocket named "Long March II F/H" rocket was under development.
In June, the Long March II F/H rocket was renamed "Long March VII" and officially established for development.
The First Academy of Space Technology (China Academy of Launch Vehicle Technology)
[15][30]
2011
In November, Long March 7 officially entered the prototype development stage
First Aerospace Academy
[35]
2012
In February, the Long March 7 rocket engine vacuum pumping system passed the test run;
On July 29, 120 ton liquid oxygen kerosene engine process acceptance test work;
In October, the first tank of the Long March 7 was taken off the shelf, creating three "firsts".
15 institutes of the First Academy of Astronautics, the Sixth Academy of Astronautics, and 211 factories of the First Academy of Astronautics
[16-17][39]
2013
In March, the booster oxidizer box of the Long March 7 rocket was completed and removed from the shelf;
In October, the first booster of the Long March 7 rocket was assembled;
In November, the power system of Long March 7 booster was tested.
On December 17, the second power system test of the Long VII rocket booster was successful.
703 Institute, 211 Plant and 101 Institute of the Sixth Aerospace Academy
[18-20][44]
2014
In March, the full rocket modal test of the Long March 7 began. The "Long March 7" rocket carried a cargo spaceship to carry out a joint test to obtain reliable test data.
In September, Long March 7 completed the booster assembly and successfully conducted two booster power system tests.
No. 211 Plant of the First Aerospace Academy
[44-45]
2015
In June, Long March 7 passed the joint review from the initial sample development to the sample development stage.
In July, the core stage modal test of the Long March 7 rocket was completed.
On October 26, the first level 200 second test run of the Long March 7 core and the 200 second swing test run of two machines were successful.
First Aerospace Academy
[47][49-50]
2016
On May 14, the Long March 7 carrier rocket arrived at Qinglan Port in Wenchang, Hainan Province from Yuanwang 21 rocket carrier.From the morning of the 15th, containers loaded with rocket parts were unloaded in batches and transported by road to the rocket horizontal transfer preparation plant at the space launch site.Enter the final assembly test phase before launch.
At 20:00:00 on June 25, 2016, China's new generation carrier rocket Long March 7 was launched atHainan Wenchang Space Launch SiteIgnition, 20:00:07:413ms, the rocket took off.About 603 seconds after the launch of the rocket, the load combination was successfully separated from the rocket and entered an elliptical orbit of 200 km perigee and 394 km apogee. The Long March 7 carrier rocket was successfully launched for the first time.This isLong March Series Launch Vehicle230th flight of[6][25]。
Carrying load
Long March 7 carrying load[27]
The load combination of the Long March 7 carrier rocket is composed of six categories and seven loads, namely, the upper stage of the Expedition 1A, the reduced scale return capsule of the multi-purpose spacecraft, the space debris active cleaning aircraft of the Flying Dragon 1, two sky pigeon aircraft, the in orbit refueling experimental device and the Flying Star.These loads are all launched for the first time, and Expedition 1A will be used as the demonstration platform to carry out 19 scientific verifications[27][40]。
Expedition 1A Upper Level: It is a spacecraft with independent flight, multiple starts, long time in orbit and other characteristics. After being launched into Earth orbit by the Long March 7 carrier rocket, it can send other payloads from one orbit to other orbits or space locations.The main task of Expedition 1A is to verify technologies such as multiple starts and long time in orbit flight, and as a carrying platform for other loads, to send the Flying Dragon 1, Flying StarSky pigeon aircraftRespectively "ferry" to different scheduled tracks and carry out relevant on orbit tests[27][40]。
Orbit map of the first flight mission of Long March 7
Multipurpose spacecraft reduced scale return capsule(hereinafter referred to as "return capsule"): the multi-purpose spaceship has a reduced height of about 2.3 meters, a maximum outer diameter of 2.6 meters, and a total mass of about 2600 kilograms. It adopts a two compartment configuration of return capsule and transition section, with a new inverted cone shape. After being carried off by Long March 7, it will fly in orbit for about 20 hours.The main task of the test is to obtain the aerodynamic and aerodynamic thermal data of the re-entry capsule flight, verify the key technologies such as the design of removable thermal protection structure and the manufacturing of new lightweight metal materials, and carry out the black barrier communication technology test to lay the foundation for the demonstration design and key technology tackling of the subsequent new manned spacecraft[27][40][42]。At 15:41 on June 26, 2016, the scaled return capsule of the multi-purpose spacecraft wasDongfeng landing siteSafe landing in the southwest Gobi area[42]。
Dragon One——Active space debris removal vehicle: based on the preliminary technical research and ground test, the key technologies of debris removal will be verified with the simulated space debris as the target, and passivation treatment will be carried out after the mission is completed[27][40]。
Sky pigeon aircraft: This time, two sky pigeon aircrafts will be carried out to carry out on orbit information relay technology tests, which can also be used as information transfer stations for space and sky information transmission[27][40]。
Tianyuan No.1On orbit filling experimental deviceIts function is similar to that of an "aerial tanker", which is used to supply satellites, space stations and other spacecraft with gas and liquid in space orbit to extend the working life of spacecraft.The on orbit injection experimental device is not separated from the upper stage of Expedition 1A, and it will be burned after re-entry after the test mission[27][40]。The "Tianyuan-1" satellite in orbit filling experiment load successfully completed 9 in orbit tests such as fluid management and filling under microgravity conditions, and high-precision propellant measurement.The telemetry and data transmission data received by the Beijing Space Flight Control Center show that the in orbit refueling test is successful[46]。
Flying Star Cubic Star: Designed with the standard cubic star conceptNorthwestern Polytechnical UniversityThe world's first 12U cubic star, with a mass of 33kg and a service life of one year in orbit, which was developed with the participation of graduate students and young teachers, will carry out a series of innovative experiments such as earth gravity field measurement, space anti radiation experiment and natural polarized light navigation technology verification[26-27][40]。
At about 15:04 on June 26, 2016Upper levelandReturn capsuleAfter the 13th circle of flight, the upper stage of Expedition 1A started the third ignition and return braking, and the return capsule and upper stage entered the predetermined return orbit.Then, the upper stage adjusts the attitude so that the return capsule presents a return attitude of more than 50 degrees to the horizontal plane.At about 15:17, the return capsule separated from the upper stage in space about 170 kilometers from the ground.After the stage return is separated, the upper stage starts the fourth ignition track braking according to the preset procedure and lifts to the safe running track.Then, the TT&C equipment of the landing site system began to implement TT&C and tracking for the re-entry capsuleBlackoutAfter waiting for the stage, at an altitude of more than 20 kilometers from the ground, the re-entry module opened the stabilizing parachute and stabilized its attitude.Then, the return capsule took off the stabilizing parachute, ejected the canopy, and opened the deceleration parachute. The main parachute was successfully opened under the drag of the deceleration parachute.At 15:41, the re-entry module successfully landed in Inner MongoliaBadain Jaran DesertHinterlandDongfeng landing siteSouthwest Gobi[28]。
The first flight of Long March 7 was successful
Implemented on August 16, 2021Tianzhou-3The Long March 7 Yao-4 carrier rocket of the mission has completed all the development work before leaving the factory and arrived safelyWenchang Space Launch Site。The Long March 7 Yao-4 carrier rocket will carry out the final assembly and testing of the launch site area together with the Tianzhou 3 cargo spaceship that has arrived earlier as planned.[62]
On January 22, 2022, it was reported that in 2022, six manned space launches would be carried out by Type III rockets, and the final assembly of Long March 7 had been completed.[67]
system composition
Announce
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overall design
The Long March 7 rocket is a two-stage rocket with a booster. Each stage uses a newly developed liquid oxygen/kerosene engine and a low-temperature pressurized transportation system developed to adapt to the engine[2]。The core primary arrow body of Long March 7 includes the rear interstage section, oxygen tank, compartment section, coal tank, rear transition section, tail section, etc;Core Level II[4]
The Long March 7 rocket has a total length of 53.1 meters, takeoff mass of about 594 tons, and takeoff thrust of 7200 kN.According to the track height of 200 ／ 400km and the track inclination of 42 degrees[53]。
Arrow body structure
The diameter of the first stage of the Long March 7 rocket core is 3.35 meters. The second stage of the core is equipped with four liquid oxygen kerosene engines, two of which are fixed and two of which swing in both directions.
The Long March 7 rocket booster is more than 20 meters long, and the single booster module is about 27 meters high. It is the longest booster in China with a diameter of 2.25 meters. It uses advanced booster and core stage bundling technology, and a 120 ton thrust liquid oxygen kerosene engine independently developed by China is used as the power source.The booster oxygen box is the longest of the rocket models in service. During the development process, a variety of advanced technologies were used, including the forming technology of electromagnetic pulse holes at the bottom of the box, the integral forging technology of fork rings, and friction stir welding technology[2][53]。
Long March 7 inherits the fairing of the improved Long March 2F rocket. The fairing diameter is 4.2 meters. The fairing and payload are transported and hoisted vertically at the launch site[4]。
propulsion system
The Long March 7 carrier rocket is a full liquid oxygen kerosene rocket, which uses new YF-100 and YF-115 liquid oxygen kerosene engines.Two sets of YF-100 (thrust 1200 kN) are installed in the first stage of the rocket core, and the engine is double pendulum;Bundle four boosters with a diameter of 2.25m, and install a single YF-100 liquid oxygen kerosene engine with a single pendulum;The second stage of the rocket core uses four YF-115 single unit thrust 180kN liquid oxygen kerosene engines in parallel, and uses two fixed engines and two double pendulums to achieve control[4]。
The control system of the Long March 7 rocket has innovatively adopted 143 intelligent control software, which is more than 30 times the amount of software used for rockets in service, greatly improving the control accuracy[55]。
The construction of Wenchang Satellite Launch Site in Hainan, China started on September 14, 2009, and 16000 mu of land was requisitioned for the construction of the launch site.Wenchang's new space launch site has "five reasons": first, its geographical location is superior;Second, large launch vehicles can be transported by sea;Third, the combination of coastal and inland areas;Fourth, the combination of high and low latitude;Fifth, combination of various shooting ranges[13]。Wenchang launch site has two launch stations. Long March 5 uses station 101, and Long March 7 uses station 201.After the Wenchang Space Launch Site in Hainan is completed and put into use, Jiuquan Satellite Launch Center will undertake such launch missions as recoverable satellites and manned space projects;Taiyuan Satellite Launch Center is mainly responsible for launching sun synchronous orbit satellites;Xichang Satellite Launch Center will mainly undertake geosynchronous orbit satellite launch mission[6]。
Wind resistant design
The ground wind at Wenchang launch site in Hainan is very common and changeable. Compared with the wind speed of about 9 meters per second on the big gobi of Jiuquan Satellite Launch Center, the wind speed at Wenchang launch site often reaches 20 meters per second. In order to ensure that the rocket can stand steadily at all times, the Long March 7 rocket is equipped with a wind proof and load shedding device, which can carry out vertical transport in the case of a force 8 wind,Wind resistance is the best of the Long March family[43]。
Design parameters
Structural dimensions of Long March 7 rocket
Rocket model
Long March 7 (CZ-7)
Long March No.7A (CZ-7A)
parameter
Cargo plan
Manned scheme
-
Height (m)
fifty-three point zero seven five
fifty-nine point four
sixty point one
Fairing diameter (m)
four point two
three point eight
4.2 (later 5.2)
Takeoff mass (ton)
About 593
About 597
five hundred and seventy
Takeoff thrust weight ratio
one point two four
one point two three
-
Takeoff thrust/ton (kN)
About 735
-
seven hundred and twenty-seven
Core diameter (m)
three point three five
-
three point three five
Booster diameter (m)
two point two five
-
two point two five
series
two point five
-
three
reliability
zero point nine eight
-
-
reference material[1][4][7][75][77]
Long March 7 carrying capacity
Target orbit
Rail height (km)
Rail inclination (°)
Carrying capacity (ton)
Typical load
LEO
200×400
forty-two
fourteen
Tianzhou-1
SSO
500×500
ninety-eight
seven point five
-
600×600
ninety-eight
six point five
-
700×700
ninety-eight
five point five
-
Remarks: 1The Long March 7 launch site is located in Wenchang Space Launch Site, China, at a latitude of 19 ° 19 ′ 00.18 ″ N.
remarks: The track parameters of the ① stage rocket separation: 200 × 394 km × 42.8 °[23]
② Orbit parameters when separating ship and arrow: 200.033 × 383.375 km × 42.808 °[24][103]
Launch mission
Long March 7 AY5 waiting[81]
At 20:55 on May 29, 2021, the Long March 7 Yao-3 carrier rocket ignited and lifted off on time at Wenchang Space Launch Site in Hainan, putting the Tianzhou-2 cargo spaceship into the scheduled orbit, and the launch was successful[60]。
At 15:10 on September 20, 2021, the Long March 7 remote four carrier rocket took off at Wenchang Space Launch Site in Hainan, China, successfully sending the Tianzhou 3 cargo spacecraft into the scheduled orbit, and the fourth launch mission of the Chinese space station in the orbit construction phase was successful[70]。
Implemented on April 11, 2022Tianzhou IVThe Long March 7 Yaowu carrier rocket of the cargo spaceship launch mission arrived at Wenchang Space Launch Site safely[68]。
At 01:56 on May 10, 2022, the Long March 7 remote five carrier rocket (hereinafter referred to as the "Long March 7 rocket") ignited and took off at Wenchang Space Launch Site in Hainan, successfully sending the Tianzhou IV cargo spaceship into the scheduled orbit, and the launch mission was successful.In 2022, the construction of China's space station officially kicked off[71]。
On September 11, 2022, after completing the relevant work in the technical area of Wenchang Space Launch Site, the Long March 7 A Yao 5 carrier rocket will be vertically transferred to the launch area (Station 201), and is expected to launch on September 13 evening[73]。
At 21:18 on September 13, 2022, the Long March 7A carrier rocket ignited and took off at the Wenchang Space Launch Site, ChinaZhongxing 1E satelliteIt soared into the sky, and then the satellite entered the scheduled orbit, and the launch mission was successful[75][81]。
On October 11, 2022, according to the China Manned Space Engineering Office, the Long March 7 remote six carrier rocket carrying out the Tianzhou 5 mission had completed all the research and development work before leaving the factory. It was safely transported to Wenchang Space Launch Site on October 11, 2022 Beijing time[82]。After that, the Long March 7 remote six carrier rocket will carry out the final assembly and testing work in the launch site area as planned together with the previously arrived Tianzhou 5 cargo spaceship[83]。
At 10:03 on November 12, 2022, the Long March 7 carrier rocket ignited and took off at Wenchang Space Launch Site in China, and then successfully sent the Tianzhou 5 cargo spacecraft into the scheduled orbit. The launch mission was successful, and the 2-hour fast rendezvous and docking will be implemented for the first time[84]。
At 06:00 on January 9, 2023, China successfully launched the Shijian 23 satellite by using the Long March 7 carrier rocket at Wenchang Space Launch Site. The satellite successfully entered the scheduled orbit and the launch mission was successful.This mission is the 459th flight of the Long March series carrier rocket.[86][88]
According to the China Manned Space Engineering Office, on May 7, 2023 (Beijing time), the Tianzhou VI cargo spaceship and the Long March VII remote seven carrier rocket combination were vertically transferred to the launch area.[90]
At 21:22 on May 10, 2023Tianzhou VIThe Long March 7 Yao 7 carrier rocket of the cargo spaceship was ignited and launched at Wenchang Space Launch Site, China. About 10 minutes later, the Tianzhou 6 cargo spaceship successfully separated from the rocket and entered the predetermined orbit. After that, the solar panels of the spaceship worked smoothly and the launch was successful.[91-92]
On November 3, 2023, China successfully launched the communication technology test satellite 10 by using the Long March 7 carrier rocket at Wenchang Space Launch Site. The satellite successfully entered the scheduled orbit, and the launch mission was a complete success.The satellite is mainly used to carry out multi band, high-speed satellite communication technology verification.[95]
On January 16, 2024, the Tianzhou VII cargo spaceship will go to the space station.This mission is the first time that the Long March 7 launch vehicle uses manual ignition, and the error must be controlled within 1 second.For possible problems, the staff has formulated more than 300 disposal measures[96]。
On January 17, 2024, the Long March 7 Remote 8 carrier rocket carrying the Tianzhou 7 cargo spaceship ignited and launched at Wenchang Space Launch Site, China, and the launch mission was a complete success.[97]
At 19:57 on June 29, 2024, China successfully launched the Zhongxing 3A satellite by using the Long March 7 carrier rocket at Wenchang Space Launch Site. The satellite successfully entered the scheduled orbit, and the launch mission was a complete success.The satellite is a communication and broadcasting satellite, which can provide users with voice, data, radio and television transmission services.[100-101]
At 20:25 on August 22, 2024, China successfully launched the Zhongxing 4A satellite by using the Long March 7 modified carrier rocket at Wenchang Space Launch Site. The satellite successfully entered the scheduled orbit, and the launch mission was a complete success.[104]
Series model
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Long March 7 development model - Table 1[4]
The Long March 7 carrier rocket is the basic type of China's new generation of medium-sized carrier rockets. Based on the Long March 7 rocket, the Long March 7A (Long March 7A) carrier rocket with high orbit launch capability has been derived.With the improvement of the technical scheme and the stability of the performance of the two types of rockets, the Long March 7 series carrier rockets can gradually replace the relevant models of China's active Long March carrier rockets, becoming the "main force" of China's future space launch missions, and carrying out more major launch missions[60]。
Long March 7 A
Long March No. 7A vertical transport[81]
The chief designer of Long March 7A carrier rocket isFan Ruixiang[78], which is based on the Long March 7 carrier rocket ("Long March 7 rocket" for short), andLong March No.3 AIt is a three-stage configuration rocket formed by the combination of three sub stages of a series of launch vehicles ("Long Triple-A Series" for short).According to the Chinese launch vehicle type spectrum planning, the Long March 7A rocket is the main configuration of a new generation of medium-sized launch vehicles, which can meet the requirements of high-density launch of large and medium-sized high orbit satellites, and is conducive to optimizing the capacity layout of space launch sites[69]。
The Long March 7A rocket has a geosynchronous transfer orbit carrying capacity of no less than 7 tons, and also has high orbit launch capabilities such as zero inclination orbit and lunar orbit.The successful development of the Long March 7A rocket has filled the gap in the capacity of China's carrier rocket to transfer 5.5 tons to 7 tons of geosynchronous orbit, and has realized the upgrading of China's medium-sized carrier rocket.In 36000km geosynchronous orbit, the Long March 7A rocket with a capacity of 7 tons will form a more optimized and reasonable capability layout together with the Long March 3A series carrier rocket with a capacity of 5.5 tons and the Long March 5 carrier rocket with a capacity of 14 tons, and improve China's space access capability,It is of great significance to promote the construction of high orbit satellite network[58][65]。
In order to adapt to the trend of further increase of satellite weight in the future, the subsequent Long 7A rocket team will also develop an improved rocket that can adapt to the fairing with a diameter of 5.2 meters by replacing the three sub stages, further improving the comprehensive performance of the Long 7A rocket[89]。
Developmental
The naming convention for the configuration of the Long March 7 medium rocket: the name is CZ-7XYZ. The X in the code represents the number of stages, Y represents the number of boosters, Z represents the type of boosters. The configuration with solid boosters is represented by S, and the liquid booster is omitted.Distinguish the status with upper level (SM);The configuration of hydrogen oxygen engine is adopted for the second stage of the core, and (HO) is added to distinguish it.For example, two solid boosters with a diameter of 2m are bundled, and the two-stage configuration of hydrogen oxygen engine is named CZ-722S (HO).According to the above naming rules, the code of basic CZ-7 is CZ-724, referred to as Long March 7 for short.
According to different rocket stages, the number of boosters is different, whether it is combined with the upper stage, etc., medium launch vehicles can build more than ten configurations Table 1 lists several typical configurations in possible combinations[4]。
In the demonstration process, the development unit analyzes the LEO and SSO carrying capacity in the two-stage (half) state, the SSO carrying capacity in the combination of two-stage half and upper stage, and the GEO carrying capacity in the three-stage half state.
LEO, SSO and GEO orbits have the following characteristics:
LEO: Rail inclination 42。, perigee 200 km, apogee 400 km (space station orbit);
SSO: 700 km high;
GEO: standard geosynchronous orbit, 35786 km.
① For medium launch vehicles, the basic Long March 7 can not only meet the needs of manned space engineering to launch cargo spacecraft, but also participate in the launch of LEO and SSO payloads in the main battlefield;The successful development can lay a good foundation for the development of other configurations of medium launch vehicles.
Long March 7 priority development models - Table 2[4]
② Among the possible configurations of medium launch vehicles, the two-stage booster free configuration CZ-720 (HO) of the first stage of Long March 7 and the three-stage combination of the existing CZ-3A series, as well as the configuration CZ-722S (HO) of the solid booster bundled on the basis of CZ-720 (HO), can meet the launch needs of most future SSO orbital satellites;These two types of rockets can be simultaneously adapted to launch at the Hainan Satellite Launch Site in Taiyuan, Jiuquan, and can take into account the launch of LEO, SSO, and GEO orbits. They have the characteristics of strong adaptability, inheritance, and expansion. Priority should be given to the development of this configuration.
③ For the selection of rockets to launch GEO payloads, the configuration of CZ-734GEO with three sub stages of CZ-3A series added on the basis of Long March 7 can reach 7 tons, which can basically meet the requirements of GEO's existing platform and future new platform standards, and priority should be given to the development of this configuration;On the basis of CZ-734, the CEO carrying capacity of CZ-732 with two boosters removed is about 4.5 tons, and the development of this configuration should be timely considered in combination with the actual needs of future GEO satellites.
To sum up, four major configurations of medium launch vehicles, including CZ-7, CZ-720 (HO), CZ-722S (HO) and more than CZ-734, give priority to development, forming a medium launch vehicle series with comprehensive delivery capacity coverage.Coverage of medium launch vehicle capacity, LEO orbit capacity covering 5.5-7.5-14 tons;SSO track carrying capacity covers 2.9-4.4-5.5 tons;GTO rail carrying capacity covers 1.5-2.4-4.5-7.0 tons[4][60]。
technological innovation
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Features of Long March 7 engine
fresh impetus——Rockets are more "environmentally friendly".
The Long March 7 carrier rocket is a "green" rocket with all liquid oxygen and kerosene. Liquid oxygen and kerosene are burned to produce carbon dioxide and water, which will not pollute the environment.The new power system is more in line with the international trend. The rocket has high safety and is easy to guarantee at the launch site[34][52]。The Long March 7 rocket has developed and applied 96 new technologies, including 12 major key technologies, with the proportion of new technologies exceeding 70%[54]。
New Layout——The reliability has been greatly improved.
Long March 7
Long March 7 uses two new types of liquid oxygen kerosene engines with independent intellectual property rights in China. Compared with conventional propellants, the specific impulse is increased by 20%, the thrust is increased by 50%, and the average cost is only one tenth of that of conventional propellants[56]。
The shape of the Long March 7 carrier rocket is not very different from the shape of the existing rockets in China, but in order to store more fuel and provide more power, its booster is about 27 meters long, nearly twice as long as the booster in service. This change requires a new design of the rocket booster.The traditional fixed booster of the rocket requires two binding points, while the Long March 7 carrier rocket adds another binding point. Compared with the static binding scheme of the active rocket, the design of the load and binding device of the Long March 7 carrier rocket is more difficult and the reliability is greatly improved[34]。
Optimization of pressurization design of tank on Long March 7 Yaosan rocket.Based on the analysis of the results of the first two flight tests, without affecting the normal use of the booster, one tank pressurization cylinder was reduced, and the tank pressurization pressure control belt of each module was optimized, which improved the utilization rate of pressurization gas[60]。
New environment——Rocket is more adaptable.
The Long March 7 carrier rocket was the first rocket launched at the new launch site in Wenchang, Hainan. Through a series of technological innovations, it overcame the new power system and the harsh force and thermal environment on the rocket and on the ground caused by the parallel connection of multiple engines;It has overcome the new challenges brought by the high temperature, high humidity, salt fog, shallow wind, lightning and other natural environmental conditions of Hainan launch site.At the same time, we always adhere to the principle of "short-term cargo, long-term manned; multiple configurations, comprehensive coverage" in design, which can be launched not only in Hainan, but also in inland launch sites such as Jiuquan, Xichang, Taiyuan in the future. The carrying capacity covers the carrying capacity required by most mainstream satellites, facing the mainstream satellite market, with a wider range of adaptation.In terms of type spectrum, Long March 7 has more diversity and flexibility in the subsequent derivative configurations of rockets, and has a wider range of adaptation[34]。
New structure——The first all digital rocket.
The Long March 7 carrier rocket has adopted 3D design/manufacturing technology, which has opened up the full 3D process from design to manufacturing (full 3D collaboration, full 3D design, full 3D manufacturing, digital simulation test, digital launch service). It is China's first "digital" rocket, marking that China's carrier rocket has entered the door of full life cycle digitization.At the same time, the rocket has adopted new processes such as integral forging ring machine plus forming fork ring, mechanical milling and roll bending forming of tank wall plate grid plate, which will further promote the implementation of the national strategy of "Made in China 2025"[34][41]。
Long March 7 Yao-3 rocket changed the rocket boost, the first stage tail end and the first stage rear transition section from composite coating to ordinary coating.After the improvement, the construction process is simplified and the production cycle is shortened.Taking the post transition section of the first level as an example, the production cycle after improvement has been shortened from about 18 days to 13 days, laying the foundation for subsequent batch production[60]。
New system——Rockets are more reliable.
The Long March 7 carrier rocket is designed according to the manned spaceflight standard. The control system and pressurization system are redundant. The control system uses three 1553B buses to control, and the information integration and flight control of the whole rocket are realized based on the three bus network;The integrated design of remote and external measurement is realized, and the important data relay transmission is realized by using space-based measurement and control, so the design reliability is higher.In the future, it will become a new generation of manned rocket for launching a new generation of manned spacecraft[34]。
New survey——Rocket launching is easier.
The vertical assembly, vertical test and vertical transition of the rocket at the launch site are called "three vertical mode".The "three vertical mode" adopted in the active rocket has to be connected to the ground twice in the technical area and the launch area, while the "new three vertical mode" adopted by the Long March 7 carrier rocket can be completed only by one docking, with better consistency of status. Moreover, the front-end ground test and launch control equipment has been fully tested in the technical area, and the probability of failure is lower after being transferred to the launch area,It effectively improves the launch reliability, and also avoids the return of the rocket to the technical area in bad weather after the transition[34]。
Long March 7 Yaosan rocket has simplified and optimized the design of on-board measurement system.The measurement parameters used for research are deleted. The number of measurement points on the arrow is reduced by about one-third, and the number of single measurement systems is reduced by nearly half. This not only saves costs, but also helps to improve the sampling accuracy of some key parameters.In addition, the Long March 7 Yao-3 rocket uses a Ka band based measurement system with high code rate. Compared with the S-band measurement system used by the Long March 7 Yao-2 carrier rocket, the transmission code rate is increased by more than 20 times, realizing no blind zone in the whole flight telemetry of the rocket[60]。
Overall evaluation
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Long March 7
The successful development of the Long March 7 carrier rocket is the beginning of the flight mission of the manned space engineering space laboratory, achieving the scheduled goal of "successful first flight", and laying a solid foundation for subsequent missions.The purpose of the first launch is to verify the design correctness and various performance indicators of the Long March 7 carrier rocket, assess the mission execution capability of the system at Wenchang Space Launch Site in Hainan, and verify the coordination and matching between the relevant systems of the project[6]。
Long March 7 carrier rocket has a low earth orbit carrying capacity of 14 tons. In terms of "strength", it is more than half of the conventional fuel carrier rocket. Therefore, it can not only achieve the launch mission of large payloads, but also use multiple start technology with the upper stage or the second stage to achieve the launch of large payloads or multi satellite networks in solar synchronous orbit[60]。
On June 26, 2016, the Associated Press reported that the Chinese space program authorities said that the return capsule of the Long March 7 spacecraft landed on the vast grasslands of Inner Mongolia, enabling China to put the second space station into orbit as scheduled later in 2016.The successful launch of the Long March 7 rocket shows that China has made a breakthrough in using safer and more environmentally friendly fuels.
Germany《Frankfurter Allgemeine Zeitung 》It is reported that the Long March 7 rocket ignited from the Wenchang Space Launch Site in Hainan Province and flew around the earth for 13 times. Its return capsule landed in the desert of Inner Mongolia.The Long March 7 carrier rocket will become the main carrier rocket of China's satellite program.Its carrying capacity is 14 tons, 1.5 times that of the original carrier rocket.
China has successfully launched the Long March 7 rocket, which can be used as a transport vehicle for the space capsule of the future space station, according to the Effie News Agency.The liquid oxygen kerosene of the Long March 7 rocket is cleaner than the original fuel.Chinese scientists spent eight years developing the rocket and also used 3D technology in its design and manufacture[29][60]。（Review of Global Network and China Academy of Launch Vehicle Technology）
