Changzheng 2 (Long March 2)
Changzheng 2 family
(From left to right) CZ-2C, CZ-2C/SD, CZ-2C2, CZ-2D, CZ-2E, CZ-2F, CZ-2F/G
The Changzheng 2 (or Long March 2 in its English translation) family of space launch vehicles, based on the Dongfeng 5 (CSS-4) ICBM of the 1970s, has been serving as a workhorse for China’s space programme for nearly forty years. Its design and liquid-propellant engines were also inherited by the Changzheng 3 and Changzheng 4 series launch vehicles. Between 1974 and 2011, various Changzheng 2 models were used in 66 launches, including 45 from the Jiuquan SLC, 11 from the Taiyuan SLC, and 10 from the Xichang SLC. The Changzheng 2F is China’s only man-rated space launch system.
Changzheng 2 Family Evolution
Dongfeng 5 / Changzheng 2
- Full article: Dongfeng 5 ICBM
In the mid-1960s, the Chinese leadership ordered to develop a true intercontinental-range missile system Dongfeng 5 that could reach North America. Technical and operational requirements for the missile were issued in March 1965. A range of new technologies had to be developed for the missile, including high-thrust rocket engine, inertial navigation guidance package, flight control, onboard computer, propellant pumping, and warhead heat shield. Two Western-trained rocket scientists, Tu Shou’e and Ren Xinmin, were in charge of the development of the missile system and its rocket engine respectively.
Political turmoil of the ’Culture Revolution’ caused a slow start in the programme. The programme definition phase began in May 1966. The development of the first-stage rocket motor was completed on 14 June 1969. The design of the missile was completed in June 1970. The ground test of the rocket motor succeeded in November 1970. The first test missile 'Batch 01-Y1' rolled out in June 1971.
The Dongfeng 5 programme suffered a major setback, when the first test flight in 1971 and the second in 1972 both failed. The Chinese premier Zhou Enlai ordered the missile development to be suspended in October 1973. The remaining four missiles from the same batch were converted into space boosters designated Changzheng 2 to support the FSW recoverable satellite programme. The launch vehicle had an LEO payload capability of 1,400kg.
On 5 November 1974, a Changzheng 2 booster carrying the first FSW satellite was launched from the Jiuquan Satellite Launch Centre (Shuang Cheng Tzu). The rocket exploded in the midair 20 seconds in the flight. Later investigation suggested that the accident was caused by a disconnected cable for the rocket’s pitch rate gyro signal. A second launch in November 1975 successfully placed the satellite into its intended orbit. The remaining two rockets were launched in 1976 and 1978, both of which also succeeded.
Changzheng 2C
The improved Changzheng 2C launch vehicle was commissioned in 1982, with its LEO payload increased to 1,800kg. Regular FSW launches were conducted from the Jiuquan centre until 1996, normally once or twice a year between August and October.
Changzheng 2C/SD
In 1993, China signed a contract with Motorola to launch 12 satellites for its Iridium global wireless communications satellite network. The Changzheng 2C/SD variant was developed for these missions. Modifications on the launcher included a 3.35m diameter payload fairing, improved second stage fuel and oxidizer tanks; and second-stage engines with higher expansion ratio nozzles.
The most important feature on the Changzheng 2C/SD was the “Smart Dispenser" (SD), a three-axis stabilised upper stage using a solid rocket kick motor for insertion of two satellites into orbit in a single launch. The solid rocket motor consists one 742kN thrust main motor and four 74.1kN swivelling venire motors, with its own onboard guidance system. The SD was developed by CALT, allegedly with the assistance of U.S. satellite companies.
Between 1997 and 1999, a total of 7 Changzheng 2C/SD launches were conducted from the Taiyuan Satellite Launch Centre (Wuzhai), sending two mock satellites and 12 operational Iridium satellites into the orbit.
Changzheng 2C/SM
The Changzheng 2C/SM featuring a spin-stabilised solid motor upper stage was introduced in the 2000s for the Double Star space scientific research satellite programme.
Changzheng 2D
The Changzheng 2D was developed by the Eighth Academy (SAST) in the early 1990s for LEO launch missions. The two-stage launcher was based on the first- and second-stage of the Changzheng 4B. By introducing improved rocket engines and increasing fuel capacity, the LEO capability of the launch vehicle was significantly increased to 3,700kg. Some variants of the Changzheng 2D also featured a McDonnell Douglas (now Boeing Aerospace) PAM-D upper stage providing 66,700 lb of thrust.
Changzheng 2E
The Changzheng 2E was developed in the late 1980s as a heavy-lift launch system to support China’s commercial satellite launch services. The launch vehicle was based on the Changzheng 2C, added with four strap-on boosters to give a LEO capability of 9,500kg, or GTO capability of 3,500kg (using a solid third-stage).
Between July 1990 and December 1995, the Changzheng 2E made a total of 8 flights from the Xichang Satellite Launch Centre, with only five of them successful. On 22 March 1992, a Changzheng 2E rocket failed to ignite on the launch pad during its first commercial satellite launch. On 21 December 1992, during the launch of Optus B2, wind shear caused the satellite to have exploded inside the rocket’s payload fairing 45 seconds into the flight. On 25 January 1995, during the launch of Apstar 2, the Changzheng 2E rocket exploded in the midair shortly after the liftoff, again caused by wind shear. The rocket was withdrawn from service after 1995.
Changzheng 2F
- Full article: 921-2 Launch System
The China Academy of Launch Vehicle Technology (CALT) was tasked with the design and development of the Project 921 launch system (code name: 921-2). Instead of developing a new rocket from the scratch, the programme designer decided to adopt an existing design Changzheng 2E, and developed it into a man-rated launch system in order to save cost. CALT began to develop the launch system in 1992, and the rocket, designated Changzheng 2F, made its first flight in 1999.
The Changzheng 2F was almost identical to the Changzheng 2E in appearance, but its onboard electronic and control systems were completely redesigned with improved system redundancy and safety measures to make it a man-rated launch system. The structure of the first- and second-stage was enhanced to support the heavier spacecraft and its launch escape system.
The launch vehicle was 58.3m tall and had a take-off mass of 479.8 tonnes. The take-off thrust was 5,923.2kN at sea level. The launch vehicle was capable of sending 8,000kg payload into the low Earth orbit. The launch vehicle consists of nine sub-systems: airframe, propulsion system, guidance and control system, propellant management system, error detection and diagnosis system, launch escape system, telemetry system, remote test system, and auxiliary system.
Changzheng 2F/G
From the Tiangong 1 mission in September 2011, an improved Changzheng 2F/G launch system succeeded the original Changzheng 2F design. The F/G variant featured an improved guidance system coupled with the GPS positioning, allowing a much higher orbit insertion of the spacecraft.
Design
The Changzheng 2 rocket was powered by a liquid bipropellant, with unsymmetrical dimethylhydrazine (UDMH) as fuel and nitrogen tetroxide (N2H4) as an oxidiser. Each stage had two main propellant tanks made of high-strength, lightweight aluminium-cooper alloy. They formed part of the stage’s thrust and weight bearing load structure and were connected by an inter-tank section. The upper tank contained the nitrogen tetroxide (N2H4) oxidiser, while the lower tank contained the UDMH fuel. Both tanks were pressurised to ensure that they didn’t collapse under their own weight. At the base of the stage is a weight bearing structure that mounted the rocket engine.
The first-stage was powered by an YF-21 rocket engine, which consists of four parallel 75t-thrust YF-20 chambers motors with swinging nozzles. The first-stage is connected to the second-stage via a mesh-bar inter-stage section. The second-stage was powered by an YF-24 engine, which consists of 75t-thrust YF-22 motor with a fixed nozzle, and a swivelling venire motor with four 4.8t-thrust YF-23 chambers. The swivelling venire motor was designed for steering and sustaining propulsion for a further 190 seconds after the shutting of the main motor, thus increasing the effective payload capability of the vehicle. The Changzheng 2E and 2F also have four strap-on boosters, each powered by a single YF-20B chambers motor with a fixed nozzle, producing a sea-level thrust of 740.4kN.
Specifications
| CZ-2C | CZ-2D | CZ-2E | CZ-2F | |
| Stages | 2 | 2 | 2 | 2 |
| Boosters | 0 | 0 | 4 | 4 |
| Overall length | 31.17m | 33.67m | 49.69m | |
| Core stage diameter | 3.35m | 3.35m | 3.35m | 3.35m |
| Take-off mass | 192t | 237t | 462t | |
| Take-off thrust | 2,786kN | 2,961.6kN | 5,923.2kN | |
| Thrust-weight ratio | 1.48 | 1.28 | 1.31 | |
| LEO capacity | 2,400kg | 3,100kg | 9,500kg | |
| First flight | 1982 | 1992 | 1990 | 1999 |
| Status | Operational | Operational | Operational | Operational |
| First-stage | CZ-2C | CZ-2D | CZ-2E | CZ-2F |
| Length | 23.72m | 24.66m | 28.47m | |
| Diameter | 3.35m | 3.35m | 3.35m | 3.35m |
| Gross mass | 151t | 192t | 199t | |
| Empty mass | 8.60t | 9.82t | 12.55t | |
| Propellant mass | 143t | 183t | 169t | |
| Engine | YF-21 | YF-21B | YF-21B | YF-21B |
| Propellant | N2O4/UDMH | N2O4/UDMH | N2O4/UDMH | N2O4/UDMH |
| Thrust, sea-level | 2,786kN | 2,962kN | 2,962kN | |
| Isp, sea-level | 2,540N.s/kg | 2,550N.s/kg | 2,556.2N.s/kg | |
| Burn time | 130s | 154.2s | 160.43s | |
| Second-stage | CZ-2C | CZ-2D | CZ-2E | CZ-2F |
| Length | 8.71m | 9.01m | 14.223m | |
| Diameter | 3.35m | 3.35m | 3.35m | 3.35m |
| Gross mass | 38.2t | 40.6t | 91.4t | |
| Empty mass | 3.2t | 3.1t | 5.0t | |
| Propellant mass | 35.00t | 34.74t | 84.76t | |
| Engine (main) | YF-22 | YF-22B | YF-22B | |
| Engine (swivelling venire motor) | 4 X YF-23 | 4 X YF-23B | ||
| Propellant | N2O4/UDMH | N2O4/UDMH | N2O4/UDMH | N2O4/UDMH |
| Thrust, vacuum (main motor) | 720kN | 719.8kN | 738.4kN | |
| Thrust, vacuum (swivelling venire motor) | 46.0kN | 46.1kN | 47.07kN | |
| Isp, vacuum (main motor) | 2,834N.s/kg | 2,822N.s/kg | 2,922.4N.s/kg | |
| Isp, vacuum (swivelling venire motor) | 2,762N.s/kg | 2,762N.s/kg | 2,834.1N.s/kg | |
| Burn time (main motor) | 112s | 113.48s | 301.18s | |
| Burn time (swivelling venire motor) | 287s | 274.42s | 414.68s | |
| Boosters | CZ-2C | CZ-2D | CZ-2E | CZ-2F |
| Length | - | - | 15.326m | 15.326m |
| Diameter | - | - | 2.25m | 2.25m |
| Gross mass | - | - | 4 X 40.75t | 4 X 40.75t |
| Empty mass | - | - | 4 X 3.0t | 4 X 3.0t |
| Propellant mass | - | - | 4 X 37.75t | 4 X 37.75t |
| Engine | - | - | 4 X YF-20B | 4 X YF-20B |
| Propellant | - | - | UDMH/N2O4 | UDMH/N2O4 |
| Thrust, sea-level | - | - | 4 X 740.4kN | 4 X 740.4kN |
| Isp, sea-level | - | - | 2,556.2N.s/kg | 2,556.2N.s/kg |
| Burn time | - | - | 127.26s | |
| Payload fairing | CZ-2C | CZ-2D | CZ-2E | CZ-2F |
| Length | 3.144m (Type A) 7.125m (Type B) |
10.5m | ||
| Diameter | 2.2m (Type A) 3.35m (Type B) |
4.20m | ||
| Mass | 1,900kg |
Last update: 23 November 2011