The Long March 7 (), or Chang Zheng 7 in

pinyin Hanyu Pinyin, or simply pinyin, officially the Chinese Phonetic Alphabet, is the most common romanization system for Standard Chinese. ''Hanyu'' () literally means 'Han Chinese, Han language'—that is, the Chinese language—while ''pinyin' ...

, abbreviated LM-7 for export or CZ-7 within China, originally Long March 2F/H or Chang Zheng 2F/H, nicknamed Bingjian (), is a Chinese liquid-fuelled

launch vehicle A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage ...

of the Long March family, developed by the

China Aerospace Science and Technology Corporation The China Aerospace Science and Technology Corporation (CASC) is a main contractor for the Chinese space program. It is state-owned and has subsidiaries which design, develop and manufacture a range of spacecraft, launch vehicles, and ground equ ...

(CAST). It made its inaugural flight on 25 June 2016. Designed as a replacement of the Long March 2F, Long March 7 and its variants was expected to be the workhorse of the fleet, projected to account for around 70% of all Chinese launches. Long March 7 plays a critical role in the

Chinese Space Station Tiangong (), officially the ''Tiangong'' space station (), is a permanently crewed space station constructed by China and operated by China Manned Space Agency. Tiangong is a modular design, with modules docked together while in low Earth ...

program: it is used to launch the Tianzhou robotic cargo and resupply spacecraft to the station. The rocket was intended to replace the Long March 2F as China's crew-rated launch vehicle in the future, although by 2023 this role has apparently been taken over by the under-development

Long March 10 Long March 10 (), also known as the “''Next Generation crewed launch vehicle''” (), and previously and unofficially as the “''921 rocket''” () or the "''Long March 5G''" (a development of the Long March 5), is a Chinese Super heavy-lift l ...

and Long March 10A. Since 2020, in addition to the base Long March 7 configuration, there is the Long March 7A (CZ-7A etc.) variant which differs from the base CZ-7 by the addition of a

liquid hydrogen Liquid hydrogen () is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecule, molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point (thermodynamics), critical point of 33 Kelvins, ...

liquid oxygen Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing. Physical ...

third stage inherited from the third stage of the

Long March 3B The Long March 3B (), also known as the CZ-3B and LM-3B, is a Chinese orbital launch vehicle. Introduced in 1996, it is launched from Launch Area 2 and 3 at the Xichang Satellite Launch Center in Sichuan. A three-stage rocket with four strap-on ...

. The rocket has also been developed into the Long March 8.

History

The Long March 7 project started in 2008 with the formation of the development team within the traditional designer of space launch vehicles, CALT. With the acquisition of the

RD-120 The RD-120 (, GRAU index: 11D123) is a Liquid-propellant rocket, liquid upper stage rocket engine burning RG-1 (propellant), RG-1 (refined kerosene) and LOX in an Staged combustion cycle (rocket), oxidizer rich staged combustion cycle with an Rock ...

technology and development of the YF-100 and YF-115 engines, the original plan was to re-engine the Long March 2F. The Long March 2F/H, as it would have been called, would "just" switch from N₂O₄ /

UDMH Unsymmetrical dimethylhydrazine (abbreviated as UDMH; also known as 1,1-dimethylhydrazine, heptyl or Geptil) is a chemical compound with the formula H2NN(CH3)2 that is primarily used as a rocket propellant. At room temperature, UDMH is a colorle ...

to a

LOX Lox is a fillet of brined salmon, which may be smoked. Lox is frequently served on a bagel with cream cheese, and often garnished with tomato, onion, cucumber, and capers. Etymology The American English word ''lox'' is a borrowing of Yiddi ...

kerosene Kerosene, or paraffin, is a combustibility, combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in Aviation fuel, aviation as well as households. Its name derives from the Greek (''kērós'') meaning " ...

propellant and improved thrust engines to offer better performance. But the switch resulted in a cascade of changes that increased the project complexity significantly. At the same time, the original

Long March 5 Long March 5 (LM-5; zh, s=长征五号 , p=Chángzhēng wǔ hào) or Changzheng 5 (CZ-5), also known by its nickname "''Pang-Wu''" (胖五, "''Fat-Five''"), is a Chinese heavy-lift launch vehicle developed by the China Academy of Launch Vehicl ...

project was expected to include heavy, medium and light versions. Since the Long March 2F/H and the medium Long March 5 had significant overlaps, it was decided to merge both projects. This way, the high reliability and flight legacy components and technologies of the Long March 2F were merged with the new technologies developed for the Long March 5. Although finished nearly at the same time, the Long March 6 was a completely separate product developed by a young team within SAST. As such, it shares little more than tank diameters and propulsion with the LM-5 and LM7, but does cover the range of payloads between the medium Long March 7 and the very light

Long March 11 The Long March 11 (), or Chang Zheng 11 as in pinyin, abbreviated LM-11 for export or CZ-11 within China (and designated 11H when launched from sea), is a Chinese four stage solid-propellant carrier rocket of the Long March family, which is d ...

. In 2010, the project name was changed officially to Long March 7. According to the project deputy manager, Zhang Tao, the project required eleven new major technologies. But the innovation was not only at the product level, but one at the process itself. This was, according to the project manager, Wang Xiaojun, the first time the whole process was developed in digital 3D, using

computer-aided design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...

directly to

computer-aided manufacturing Computer-aided manufacturing (CAM) also known as computer-aided modeling or computer-aided machining is the use of software to control machine tools in the manufacturing of work pieces. This is not the only definition for CAM, but it is the most ...

. The inaugural flight was successfully performed on 25 June 2016, at 12:00

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

from the

Wenchang Wenchang ( postal: Mencheong; ; Hainanese spellings: Boon Siou) is a county-level city in the northeast of Hainan Island in China. Covering an area of , the city has a coastline of , and is divided into 17 towns. The city is a major target for t ...

, LC-2 launch pad. It launched in the LM-7 configuration with the addition of the simultaneously debuting Yuanzheng-1A upper stage; the flight performed its multi-orbit mission successfully.

Design

The Long March 7 is the medium-lift variant of a new generation rocket family that includes the heavier-lift

and the small-mid cargo

Long March 6 The Long March 6 () or Chang Zheng 6 as in pinyin, abbreviated LM 6 for export or CZ 6 within China, is a Chinese liquid-fuel rocket, liquid-fuelled launch vehicle of the Long March (rocket family), Long March family, which was developed by t ...

. The structure is based on the reliable,

human-rated Human-rating certification, also known as man-rating or crew-rating, is the certification of a spacecraft or launch vehicle as capable of safely transporting humans. There is no one particular standard for human-rating a spacecraft or launch veh ...

Long March 2F launch vehicle. It inherited the 3.35 m-diameter core stage and 2.25 m-diameter liquid rocket boosters. Where the earlier

Long March 2 Long March 2 rocket family or Chang Zheng 2 rocket family as in Chinese pinyin is an expendable launch system operated by the People's Republic of China. The rockets use the abbreviations LM-2 family for export, and CZ-2 family within Chi ...

rocket family used expensive and dangerous /

propellants, the Long March 7 uses

and

. The engines are shared with the Long March 5 and 6. The goal was to build a more cost-effective and less hazardous rocket family to replace today's Long March 2 and eventually the Long March 3. It is capable of placing a payload into a

Sun-synchronous orbit A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

(SSO) of .

Stages

The Long March 7 inherits the modular stages of the original

project. As such, its first stage is the same module as the LM-5 boosters. It also shares tank diameters and engines with the

, but the design groups were completely different. The LM-5 and LM-7 were developed by

China Academy of Launch Vehicle Technology The China Academy of Launch Vehicle Technology (CALT) is a major state-owned civilian and military space launch vehicle manufacturer in China and one of the major launch service providers in the world. CALT is a subsidiary of the larger China A ...

(CALT), while the LM-6 was done by Shanghai Academy of Spaceflight Technology (SAST). Even the avionics are different. The basic Long March 7 can be optimized by varying the number of boosters or enhanced by the addition of upper stages. These stages allow more mission flexibility, like direct injection to higher orbits or multiple orbit deployment. They can also increase the performance significantly. Thanks to this modularity, performance can be dialed between and for LEO, and for SSO and and to

Geostationary transfer orbit In space mission design, a geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a highly elliptical type of geocentric orbit, usually with a perigee as low as low Earth orbit (LEO) and an apogee as high as geostationary orbit ...

(GTO).

Boosters

The Long March 7 can use 0, 2 or 4 boosters using

RP-1 RP-1 (Rocket Propellant-1 or Refined Petroleum-1) and similar fuels like RG-1 and T-1 are highly refined kerosene formulations used as rocket fuel. Liquid-fueled rockets that use RP-1 as fuel are known as kerolox rockets. In their engines, RP- ...

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicle ...

. They are powered by a single oxidizer-rich staged combustion YF-100 engine. Each boosters supplies at sea level and in vacuum of thrust. Its

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine, such as a rocket engine, rocket using propellant or a jet engine using fuel, generates thrust. In general, this is a ratio of the ''Impulse (physics), ...

is at sea level and in vacuum. Each module has its own single axis

thrust vector control Thrust vectoring, also known as thrust vector control (TVC), is the ability of an aircraft, rocket or other vehicle to manipulate the direction of the thrust from its engine(s) or motor(s) to control the attitude or angular velocity of the veh ...

, and thus it required a special design in the control systems of the rocket to coordinate all the rocket's nozzles. They use the legacy width of the

and

Long March 3 The Long March 3 (), also known as the Changzheng 3, CZ-3 and LM-3, was a Chinese orbital carrier rocket design. They were all launched from Launch Area 3 at the Xichang Satellite Launch Center. It was a three-stage rocket, and was mostly used ...

families, but due to the increased thrust of the YF-100 with respect to the

YF-20 The YF-20 is a Chinese liquid-fuel rocket engine A rocket engine is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed Jet (fluid), jet of high-temperature gas ...

and YF-25, the boosters are almost twice as long, at . A Long March 7 rocket booster created a fireball visible from portions of

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

and

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

on the evening of 27 July 2016; its disintegration was widely reported on

social media Social media are interactive technologies that facilitate the Content creation, creation, information exchange, sharing and news aggregator, aggregation of Content (media), content (such as ideas, interests, and other forms of expression) amongs ...

, and the uncontrolled re-entry of such a five-ton object was regarded as a rare event.

First stage

The first stage has diameter tanks carrying RP-1/LOX propellant. It is powered by two YF-100 engines, sharing the same propulsion elements as the boosters, only that for the first stage the engines can gimbal in two axes. Also, this first stage is the same basic module as the

boosters. The diameter was designed for land transport and as such, it will be able to launch from all the Chinese launch sites. This is a critical difference to the LM-5 that requires water transport for its core stages. While it shares diameter and engines with the

first stage, the development was completely separated and done by different groups.

Second stage

The second stage also shares the first diameter tanks and propellant. It is powered by four oxidizer-rich staged combustion RP-1/LOX YF-115 engines. Two are fixed and two can gimbal in two axis. It offers of thrust in vacuum with a specific impulse of . While it shares engines with the Long March 6 second stage, the development were completely separated and done by different groups.

Optional stages

Yuanzheng-1A

It can use the Yuanzheng-1A upper stage to increase payload to higher energy orbits and enable multiple ignition missions. Particularly, allows direct injection to SSO orbits. The inaugural flight successfully used this upper stage to deliver multiple payloads to different orbits.

Hydrogen stage

The Long March 7 is expected to be enhanced by a high-energy

and

stage. This stage and the low inclination of Wenchang would enable to launch payload between and to

(GTO) orbit. That would be a 25% increase with respect to the previously most powerful Chinese launcher, the

, but well below the

. The Long March 7A variant, active since March 2020, accomplishes just this enhancement; it is made of the initial two stages of Long March 7, with a third stage powered by liquid hydrogen and liquid oxygen. In the 2013 presentation of variations, a hydrogen-powered stage was also used as a second stage. It was not clear if it would be the same stage used as the second stage or a different stage. In both cases (second and third stage) they would be powered by the

YF-75 The YF-75 is a liquid cryogenic rocket engine burning liquid hydrogen and liquid oxygen in a gas generator cycle. It is China's second generation of cryogenic propellant engine, after the YF-73, which it replaced. It is used in a dual engine mou ...

or the YF-75D.

Solid boosters

The 2013 presentation of the variation also proposed smaller diameter solid boosters as a cheaper option for smaller payloads.

Avionics

After the inaugural flight, Song Zhengyu, Deputy Chief Control Systems Designer for the Long March 7 project, stated that the flight had proven indigenous

avionics Avionics (a portmanteau of ''aviation'' and ''electronics'') are the Electronics, electronic systems used on aircraft. Avionic systems include communications, Air navigation, navigation, the display and management of multiple systems, and the ...

. They had to work with the local industry to develop space rated dual processor PLCs. It was also stated that the

real-time operating system A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. A RTOS is distinct from a time-sharing operating system, such as Unix ...

was also an indigenous development. The general design was based on a distributed architecture to enable

scalability Scalability is the property of a system to handle a growing amount of work. One definition for software systems specifies that this may be done by adding resources to the system. In an economic context, a scalable business model implies that ...

and

fault tolerance Fault tolerance is the ability of a system to maintain proper operation despite failures or faults in one or more of its components. This capability is essential for high-availability, mission-critical, or even life-critical systems. Fault t ...

. This avionics would be the base for most future developments and had been designed with

reusability In computer programming, reusability describes the quality of a software asset that affects its ability to be used in a software system for which it was ''not'' specifically designed. An asset that is easy to reuse and provides utility is conside ...

in mind.

2013 proposed variations

In a paper published on the ''Manned Spaceflight'' publication of the CMSEO, the Long March 7 was presented as a family of launch vehicles. The variations would be codified by a two number plus variable letters code, and a CZ-7 prefix in the form CZ-7##. The first digit would mean the number of stages in the core, which could be either 2 or 3. The second number would mean the number of boosters, which could be 0, 2 or 4, with an S appended if the boosters were of solid type. There was also proposed an alternative second stage powered by the LH/

propellant and dual

engines would be identified by appending an (HO) to the designation. At last, it could have an additional upper stage, later identified as the Yuanzheng-1A, that would be identified by appending to the designation /SM. For example, the version that debuted was codified under this nomenclature as the ''CZ-724/SM'', since it had two

core stages, four liquid boosters and was enhanced by the Yuanzheng-1A stage. A ''CZ-720'' would have two RP-1/LOX stages and no boosters. A ''CZ-724S(HO)'' would have a RP-1/LOX first stage, a LH/LOX second stage and four solid boosters. A ''CZ-732'' would have two RP-1/LOX stages, a LH/LOX third stage, and two liquid boosters. The paper expected the following performance from certain versions. The paper also presented the propulsion options for each stage. The

second stage had only two YF-115 instead of the normal four, when used in the version with no boosters. It might have implied a different smaller upper stage or an under filled one.

CZ-7A variant

Since 2020, the base two-stage CZ-7 configuration has been supplemented by the CZ-7A variant. This variant employs the boosters and the first two stages of the base configuration, and add to this a third stage that employs two cryogenic

engines operating on and

liquid fuels; the third stage of the 7A variant is inherited from the third stage of the

. (Note that the 7A variant is similar to the CZ-73X variants first proposed in 2013; see previous subsection). The maiden CZ-7A was launched on 16 March 2020 at 13:34 UTC from Wenchang Satellite Launch Center on Hainan island. Two hours after launch, state news sources announced that the flight ended in failure; no causes for the failure were indicated initially. Launch preparations for the maiden flight continued in the weeks prior to launch despite measures taken to combat the spread of the COVID-19 virus in China. In 2021, some observers speculated, based on unconfirmed Chinese

Baidu Baidu, Inc. ( ; ) is a Chinese multinational technology company specializing in Internet services and artificial intelligence. It holds a dominant position in China's search engine market (via Baidu Search), and provides a wide variety of o ...

posts, that the failure of the CZ-7A's maiden flight was caused by the loss of pressurization in one of its four boosters just prior to ''main engine cutoff'' and the '' staging'' of the first stage (about 168 seconds into the flight). The second CZ-7A launched successfully from Wenchang on 11 March 2021. The launch vehicle carried the Shiyan-9 satellite to test new technologies such as space environmental monitoring, according to the

(CASC).

Launch Statistics

List of launches

References

{{China space station Long March (rocket family) Vehicles introduced in 2016 2016 in China 2016 in technology