DF-5 / CSS-4

The Dong Feng-5 (DF-5, or CSS-4 in its U.S. DoD designation) is a two-stage, liquid-propellant, single-warhead intercontinental ballistic missile (ICBM), which has also been developed into a space launch vehicle under the designation Long March 2.

The DF-5 ICBM was the last of the four missile-delivery systems (short-range, medium-range, intermediate-range, and intercontinental) to be developed under the Chinese missile industry’s Eight-Year Development Plan (1960—1967). The development of the ICBM was authorised in March 1965, with the objective to conduct the first test launch in 1971 and receive design certification in 1973. Two Western-trained rocket engineers, Tu Shou’e and Ren Xinmin, were put in charge of the missile’s overall design and liquid engine respectively.

The DF-5 concept was described as a two-stage, liquid propellant rocket, with the first-stage powered by four parallel YF-20 liquid engine with swinging nozzles (260 t thrust in total) and second-stage powered by a single engine (65 t thrust) and four vernier thrusters (1 t thrust each). The missile would use an advanced inertial guidance package with digital computer and fluid-suspended gyrostabilised platform. Given that the missile will need to be transported from the manufacturing factory to the launch site by railway, its body diameter was limited by the loading gauge of the Chinese railway lines. As a result, the body diameter was set at 3.35 m.

The development and testing of the DF-5 was to be shared between a number of organisations:

  • 1st Academy of Seventh Ministry of Machine Building (Beijing): Missile’s overall design
  • Base 067 (Xi’an): Liquid engines
  • 211 Factory (Beijing): Missile manufacturing
  • Base 062 (Chengdu): Missile manufacturing
  • Chinese Academy of Sciences: Digital guidance computer (Project 156) and fluid-suspended gyrostabilised platform (Project 157)
  • National Defence Science & Technology Commission: Missile test range including launch site and target zone

The YF-20 on the DF-5 first-stage was more powerful than any previous rocket engine developed by China, rated at 75 tonnes each. A total of four YF-20 engines arranged in a parallel configuration formed the engine pack designated YF-21. The YF-20 was developed from the YF-1 engine, with two 5D10 (YF-1) turbo-pumps in parallel to pump the propellants into the rocket chamber. The concept of the YF-20 was produced in August 1965, and the detailed design was completed by November 1967. The second-stage was to be powered by a high-altitude version of the YF-20, designated YF-22, with 65 t thrust. The 4 vernier thrusters rated at 1,000 kg each.

By June 1967, the DF-5’s propellants choice, method for propellant tank pressurisation, guidance method, and warhead control method had all been finalised. The conceptual design was concluded in January 1968, though many technical details remained unanswered. As the 1st Academy and the Seventh Ministry of Machine Building both focused their resources on the artificial satellite project, little progress was made in the DF-5 development. The detailed design was not completed until March 1970.

The YF-20 engine passed its first long-duration ground burn test in February 1968, followed by the long-duration burn test at 101 Station in December. The engine completed 8 gimbal tests between December 1969 and May 1970. The combined YF-21 engine pack completed the first ground burn test in June 1969 and passed its gimbal test in October 1970. The second-stage YF-22 engine completed 6 ground burn tests between October 1969 and June 1970. The entire YF-24 engine pack (YF-22 plus 4 YF-23) passed ground burn test by December 1970.

With the successful launch of Dong Fang Hong 1 in April 1970, the development of DF-5 as both an ICBM and a space launch vehicle was back on the agenda. However, by then the operations of China’s political apparatus and defence industry had been seriously interrupted by the so-called ‘Cultural Revolution’. A ‘705 Campaign’ was launched under the leadership of the National Defence Science and Technology Commission (NDSTC) and the Beijing municipality government, in order to ready the missile for its first test launch by October. Standard operating procedures were ignored to save time, resulting in many design flaws and poor product qualities.

The first DF-5 test launch using a depressed trajectory (DT) from Jiuquan on 10 September 1971 was only partially successful, with the second-stage shutting down earlier than expected and as a result the warhead overshooting the target zone by 565 km. The second test launch on 8 April 1973 failed when an anomaly occurred at T plus 43 seconds, triggering the missile to self-destruct. Chinese Premier Zhou Enlai ordered the DF-5 development to be suspended, and the remaining 4 missiles in the Batch-01 production to be converted into the Long March 2 launch vehicle for the FSW recoverable satellite missions.

The DF-5 tests resumed four years later in September 1977, after the 1st Academy introduced a modified design with downgraded performance (8,000 km range instead of 10,000 km). A number of depressed trajectory (DT) tests of the DF-5 were successfully conducted between October 1978 and October 1979, though the issues with the heat shielding of the re-entry vehicle (warhead) were not fully resolved until 1979.

The full-range flight test of the DF-5, codenamed “580 Mission”, took place in March 1980, with two missiles fired from Jiuquan to the target zone in the South Pacific. The PLA Second Artillery Corps began to deploy the DF-5 in underground silos in 1981, though the missile was not officially certified for design finalisation until December 1986. The missile was revealed to the public of the first time on 1 October 1984, when three DF-5 missiles were displayed during the National Day military parade in Beijing to celebrate the 35th anniversary of the founding of the People’s Republic of China.

DF-5 at Launch Complex 2 in Jiuquan
DF-5 at Launch Complex 9 in Taiyuan

Specifications

Stages:....................2
Overall length (m):........32.61
Core stage diameter (m):...3.35
Take-off mass (kg):........181,000
Maximum range (km):........8,000 to 10,000
Payload:...................Single 3 MT thermal nuclear
Guidance:..................Inertial

First-Stage
Length (m):................N/A
Diameter (m):..............3.25
Dry mass (kg):.............N/A
Propellant mass (kg):......N/A
Engine.....................YF-21 (4 x YF-20)
Propellant:................Liquid (UDMH/N2O4)
Thrust (kN):...............2,500

Second-Stage
Length (m):................N/A
Diameter (m):..............3.25
Dry mass (kg):.............N/A
Propellant mass (kg):......N/A
Engine.....................YF-24 (YF-22 plus 4 x YF-23)
Propellant:................Liquid (UDMH/N2O4)
Thrust (kN):...............N/A

Chronology

1965 March: DF-5 development began

The 11th Session of the Central Special Committee authorised the proposal for the development of the DF-5 ICBM, with the objective to conduct the first test launch in 1971 and receive design certification in 1973. The National Defence Science and Technology Commission was responsible for the construction of the launch site and warhead impact zone. The Chinese Academy of Science was responsible for the development of the digital computer (Project 156) and fluid-suspended gyrostabilised platform (Project 157).


1967 June: DF-5 design proposal finalised

The missile’s propellants choice, method for propellant tank pressurisation, guidance method, and warhead control method were finalised, allowing the design phase to commence.


1968 January: DF-5 conceptual design completed

The conceptual design stage had been completed, allowing the detailed designs stage to commence, though many technical details remained unsolved. The 19th Session of the Central Special Committee issued a resolution demanding the Seventh Ministry of Machine Building to allocate resources to support the DF-5 project, though little progress was made over the next three years as the ministry was busy with the artificial satellite project (Dong Fang Hong 1).


1968 February: First long-duration ground burn test of the YF-20 succeeded

The engine produced a thrust of 69 tonnes for a duration of 249 seconds during the test.


1970 Spring: ‘705 Campaign’ launched to speed up the ICBM development

A total of 178 organisations, including 11 industrial bureaus, 5 districts, 6 institutes, and 12 ministries were involved in the campaign aimed to speed up the ICBM development. The programme set an ambitious target to conduct the first test launch of the missile in October 1970, though soon it became apparent that such a target was unrealistic. Standards and procedures were ignored to save time, resulting in design flaws and poor product qualities in the development.


1970 October: YF-21 gimbal test completed

The first gimbal test of the DF-5 first-stage (YF-21) was carried out in June, and the system passed all ground tests in October, marking the last major milestone in the development of the first-stage propulsion system.


1970 December: YF-24 development completed

The DF-5 second-stage (YF-24), consisting of the YF-23 engine and four vernier thrusters, passed all ground tests.


1970 November: Batch-01 production of the DF-5 began

Assembly of the first batch production of missiles began and the first missile rolled out in June 1971. However, many issues remained and it took the engineers three months to test the missile.


1971 June: Launch campaign began for the first DF-5 test

The first flying example of the DF-5 was delivered to the Jiuquan missile test centre, marking the beginning of the launch campaign for the first flight test using a depressed trajectory.


1971 September 10: First DF-5 test launch

The missile initially flew normally but the second-stage engine shut down earlier than expected, resulting in the warhead overshooting the target zone by 565 km. The flight test was declared a partial success. Later investigation suggested that the anomaly was caused by an error with the missile’s guidance computer.


1972 December 26: Second DF-5 test launch aborted

An umbilical cable was disconnected unexpectedly due to a short-circus on the control board, resulting in two of the four engines on the first-stage failing to ignite. The engines had an emergency shutdown and the launch was aborted. The missile was then removed from the launch pad and returned to the factory for repairing.


1973 April 8: DF-5 test launch failed

The repaired missile was put back on the launch pad. The missile lifted off rom Pad 138 at Launch Complex 2 in the Jiuquan launch centre. Only 43 seconds into the flight, an anomaly occurred triggering the missile to self-destruct. Chinese Premier Zhou Enlai subsequently ordered the DF-5 development to be suspended, and the remaining 4 missiles in the Batch-01 production to be converted into Long March 2 launch vehicles to support the FSW recoverable satellite missions.


1974 January: DF-5 Batch-02 production development began

10 key modifications were made to the DF-5 design to address the issues exposed during the first two flight tests. The Batch-02 production would deliver 10 missiles, including 8 for special trajectory (depressed or elevated) flight test and 2 for full-range flight test.


1977 September: DF-5 was listed as one of the three key defence and aerospace projects

With the ending of the Cultural Revolution, some normalities returned in the defence and aerospace industry, allowing the engineers to iron out the design flaws and technical issues in the DF-5 design. The development also sped up as a result.


1978 October 5: DF-5 flight test (depressed trajectory)

The first DT flight test from Jiuquan succeeded.


1979 April 5: DF-5 flight test (depressed trajectory)

The second DT flight test from Jiuquan succeeded.


1979 January 7: DF-5 flight test (elevated trajectory)

The first ET flight test from Taiyuan succeeded.


1979 June to November: Multiple DF-5 flight tests (elevated trajectory)

Multiple RT flight tests from Taiyuan, all of which were successful.


1980 May 18: First DF-5 full-range flight test (580 Mission)

Preparation for the DF-5 full-range flight test (580 Mission) began in late 1977. The target impact zone was selected in the South Pacific near the Equator, some 1,000 km east of Solomon Islands. Some 70,000 people from over 30 government agencies, the 4 service branches and 10 military region commands of the PLA, and 27 provincial and municipal governments took part in the campaign. A naval task force consisting of 18 naval vessels, including 8 newest Type 051 destroyers, and 4 helicopters was deployed to the target impact zone to recover the re-entry vehicle.

At 10:00 local time on 18 May 1980, the first DF-5 missile took off from Pad 138 of Launch Complex 2 at Jiuquan and flew downrange to the target zone in the southeast. After a 30-minute flight over a distance of 9,000 km, the missile’s re-entry vehicle landed in the target impact zone and was successfully recovered.


1980 May 21: Second DF-5 full-range flight test

A second DF-5 missile was launched from Pad 5020 of Launch Complex 2 at Jiuquan. However, the re-entry vehicle missed the target impact zone by several hundred kilometres due to a second-stage malfunction.

Published by

SinoX

Freelance reporter and writer. Chinese military and space programme observer. Editor and publisher of SinoDefence.com and ChinaSpaceReport.com

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