The Long March 2F (LM-2F; ), also known as Chang Zheng 2F (CZ-2F), is a Chinese human-rated two-stage hypergolic-fuelled medium-lift launch vehicle, part of the Long March 2 rocket family. Launching the Shenzhou spacecraft on all 22 flights of the Shenzhou program, it is one of three in-service orbital rockets worldwide to have launched multiple crews, alongside Russia's Soyuz-2 and the US Falcon 9.

The Long March 2F is a two-stage version of the Long March 2E rocket, which in turn was based on the Long March 2C launch vehicle. The entire family is based on the Soviet R-2. The rocket is entirely fuelled by the hypergolic mixture of unsymmetrical dimethylhydrazine and dinitrogen tetroxide. The first stage is powered by four YF-20B engines, as well as four boosters each with one such engine; the second stage uses one YF-24 engine.

It is launched from complex SLS at the Jiuquan Satellite Launch Center. The Long March 2F made its maiden flight on 19 November 1999, with the Shenzhou 1 spacecraft. After the flight of Shenzhou 3, Chinese President Jiang Zemin named the rocket Shenjian (, ).

On 15 October 2003, a Long March 2F launched Shenzhou 5, China's maiden crewed mission and achieved its first human spaceflight. Since then, the rocket has launched twenty-one more missions into orbit with the latest being the Shenzhou 23 spacecraft. Since 2021, it provides crew access to the Tiangong space station. The rocket launched the prototype space stations of the Tiangong program: Tiangong-1 (crewed 2012 and 2013) and Tiangong-2 (crewed 2016). The Long March 2F is also the launch vehicle for the clandestine Chinese reusable experimental spaceplane.

Differences from the Long March 2E

Externally, the rocket is similar to the Long March 2E from which it was derived. Most of the changes involve the addition of redundant systems to improve safety, although there are some structural modifications that allow the rocket to support the heavier fairing required by the Shenzhou capsule. The rocket is also capable of lifting heavier payloads with the addition of extra boosters to the first stage.

The rocket also has an "advanced fault monitoring and diagnosis system to help the astronauts escape in time of emergency" (in other words, a launch escape system), and is the first Chinese made rocket to be assembled and rolled out to its launch site vertically.

Derivatives

The Long March 2F/G and Long March 2F/T are improved variants of the Long March 2F. Development of the upgraded versions was approved in 2004, and first launched on 29 September 2011 carrying the Tiangong-1 space laboratory.

The improved variants introduced extensive changes to the rocket's core systems. The booster propellant tanks were redesigned with conical upper sections instead of elliptical domes, increasing propellant capacity and improving low Earth orbit performance. Booster separation was also delayed from 140 seconds after liftoff to 153 seconds, shortly before first-stage separation.

The Long March 2F/G variant has been used for all Shenzhou missions since Shenzhou 8 and retains the launch escape system. The Long March 2F/T variant was developed for uncrewed missions including Tiangong-1 and Tiangong-2. It omits the escape tower and uses a larger payload fairing to accommodate larger spacecraft. It has also been used to launch the Chinese reusable experimental spacecraft, where it uses a special fairings with bulges to accommodate portions of the payload without requiring a larger overall fairing.

The Long March 2F/G has a length of , a liftoff mass of , a fairing diameter, and a low Earth orbit payload capacity of . The Long March 2F/T has a length of , a liftoff mass of , a fairing diameter, and a low Earth orbit payload capacity of .

Beginning with the Shenzhou 12 mission, the Long March 2F/G entered a dual-vehicle standby mode at the Jiuquan Satellite Launch Center to support emergency crew-return requirements during construction and operation of the Tiangong space station. Under this arrangement, one launch vehicle remained prepared as a backup while another was assigned to the scheduled mission. Preparation time was later reduced from 49 days for Shenzhou 12 to 35 days by Shenzhou 15.

Vibration issues

During the Shenzhou 5 mission, Yang Liwei experienced discomfort caused by heavy vibration during launch. Although later modifications reduced the problem, vibrations were again reported during Shenzhou 6, leading to additional design changes. According to Long March 2F chief designer Jing Muchun, "We made changes to the pipelines of the rocket engine, adjusting its frequency. A new design for the pressure accumulator produced evident results. The vibration has now been reduced by more than 50%". During launch preparations for the Shenzhou 14 mission, chief designer Gao Xu stated that incremental design improvements had reduced vibration levels experienced by taikonauts to those comparable to riding in a car on a highway.

The Long March 2E rocket on which the 2F was based, also experienced vibration-related problems. During two launches, excessive vibration caused the collapse of the payload fairing, destroying the Optus B2 and Apstar 2 satellites. Even after the payload fairing was redesigned, excessive vibration damaged the AsiaSat 2 satellite during launch. The Long March 2E rocket was retired from service on 28 December 1995.

Gallery

Launch statistics

List of launches

See also

• List of Long March launches (2025-2029)

References