DF-4

The Dong Feng-4 (DF-4, CSS-3) is a liquid-propellant, nuclear-tipped intermediate-range ballistic missile (IRBM) introduced in the late 1980s, capable of hitting targets in the West Pacific, South Asia, and European Russia.

  • PLA designation: Dong Feng-4 (DF-4)
  • NATO code name: CSS-3
  • Type: Intermediate-range ballistic missile
  • Designer: China Academy of Launch Vehicle Technology (CALT)
  • Manufacturer: Capital Astronautics Machinery Co. (Factory 211)
  • Payload: Single 3.3 MT-yield thermonuclear
  • Range: 4,700 km
  • Propulsion: Two-stage liquid (NO3/UDMH)
  • Guidance: Cascade compensation inertial
  • Basing: Underground silo storage and above-ground launch, or tunnel storage and roll-out on transporter-erector (TE)
  • In service: 1988
  • Status: Operational

Programme

Development History

The development of the intermediate-range ballistic missile was first proposed in the mid-1960s following the initial success in the short- and medium-range ballistic missiles. According to the 10-Year Plan of Defence Science and Technology published in 1963, the next phase of the Chinese surface-to-surface missile programme was to grasp the multi-stage rocket technology for the development of the intercontinental ballistic missile (ICBM) and space launch vehicle (SLV).

To demonstrate the relevant technology, the 1st Academy (CALT) of the Seventh Ministry of Machinery Industry (Ministry of Astronautics) proposed to develop the single-stage DF-3 medium-range ballistic missile into a two-stage rocket SDF-4 as a technology demonstrator. The DF-3 would form the first-stage of the SDF-4, added with a second-stage powered by a single YF-1 liquid engine.

Facing an escalating conflict in Vietnam and possible invasion by the Republic of China (ROC) forces in Taiwan, the Chinese political leadership decided in 1964 to speed up the country’s missile and nuclear weapon programme. As a result, a decision was taken in March 1965 to develop the SDF-4 into an operational missile under the designation DF-4, with the objective of fielding a 4,000 km-range missile capable of hitting U.S. bases in Guam. The missile development plan including the intermediate-range DF-4 and intercontinental range DF-5, was officially approved 20 March 1965.

Under the instruction of the Central Special Committee, the Seventh Ministry of Machinery Industry initiated the DF-4 development in May 1965, with Ren Xinmin appointed Chief Designer for the programme. The development team was formed by July 1965. Shortly after the DF-4 development began, the 1st Academy successfully conducted ground testing of the YF-1 liquid engine using the improved N2O4/UDMH bi-propellant replacing the original HNO3/UDMH bi-propellant. As the result, the 1st Academy proposed the improved DF-4A with a new engine burning the N2O4/UDMH bi-propellant as well as a new guidance package.

After some internal debate, the Seventh Ministry decided to continue with the original DF-4 design to avoid delay in the development programme. The technical specifications of the missile were finalised on 31 May 1966. In May 1966, the National Defence Science Commission (NDSC), the China Academy of Sciences (CAS), and the Seventh Ministry of Machinery Industry approved the plan to develop the DF-4 into an orbital launch vehicle for the launch of China’s first artificial Earth satellite. The launch vehicle, designated CZ-1 (Chang Zheng-1, or Long March 1), would be based on the DF-4 but added with a solid-propellant third-stage to deliver the 100 kg satellite to a 2,384 x 439 km Low Earth Orbit (LEO).

The development of the DF-4 was seriously disrupted by the political turmoil of the ‘Cultural Revolution’ in the late 1960s. To avoid any delay in the development programme, Chinese Premier Zhou Enlai personally asked all staff working on the programme to remain on their roles and barred them taking part in the political activities.

Between 1967 and 1969, a series of ground tests on the missile’s airframe and rocket engines were carried out. As the existing “Project 150” optical tracking system could not meet the requirements for long-range missile testing, the improved “Project 154-I” telemetry and tracking system consisting of both radar and optical tracking systems was developed and installed at the Jiuquan Missile Test Centre (Base 25) in 1969. A new launch complex was commissioned at the Jiuquan centre in December 1966. A new missile test centre (Base 28) also began construction in April 1967 in Jilin Province in northeast China to allow the full-range DF-4 flight testing. The centre was activated in August 1970.

DF-4 / CZ-1 Testing

By July 1969, the Seventh Ministry of Machinery Industry had drafted the test flight plan for the DF-4 Batch-01 testing. Two missiles were delivered to the Jiuquan Missile Test Centre (Base 20) in late August 1969 for partial-range (depressed trajectory) flight test. The first missile (Y1) was erected on the launch pad in October 1969 but the missile’s engine was damaged in an accident and as a result the whole missile was withdrawn. A second missile (Y2) was launched on 16 November, but missile’s first- and second-stage failed to separate during flight. The repaired Y1 missile was put back to the pad and launched on 30 January 1970. The missile flew normally and hit its target zone with satisfactory accuracy.

On 24 April 1970, a modified three-stage DF-4 using the designation CZ-1 was launched from Jiuquan, successfully placing China’s first experimental satellite Dong Fang Hong 1 into Earth orbit. On 23 November 1970, a DF-4 was launched from the Northeast Missile Test Base (Base 28), but the missile suffered another stage separation failure. On 3 March 1971, a second CZ-1 launch vehicle successfully placed the Shijian 1 satellite into orbit.

It took the design team a whole year to identify the causes for the DF-4 failures. On 15 November 1971, a second DF-4 test launch was conducted from Base 28. The missile flew normally over a distance of 3,772 km to its target impact zone, though the re-entry vehicle was destroyed during re-entry.

DF-4 Extended Range

The DF-4 was originally intended for targeting U.S. bases in Guam. However, the worsening relations with the Soviet Union led to the decision in May 1970 to increase the missile’s range to 4,700 km in order to reach targets in Europe Russia from western China. A modified engine with increased thrust and prolonged burn time successfully passed the 280-second ground test in July 1970, but the modified missile was not completed until 1976 due to the disruptions of the ‘Culture Revolution’.

Two test launches of the revised DF-4 Batch-02 design using depressed trajectory were carried out on 15 May and 25 August 1976, both of which were successful. The third full-range flight test on 30 September 1977 failed after the missile was self-destructed 84 seconds into the flight. A second test launch was carried out 22 November 1977, and the missile carrying a dummy warhead flew normally over a distance of 4,167 km to its target impact zone. This was also the first operational test conducted by the PLA Second Artillery Corps.

To speed up the missile development, Li Yiming was appointed the DF-4 chief designer in January 1978, and Dong Chun was appointed the programme’s chief director in April 1979. Three full-range DF-4 flight tests were carried out on 31 July, 16 September, and 23 December 1978. The first two tests were successful but the third test failed.

To demonstrate the storability of the liquid propellant, a fully-fuelled DF-4 missile was stored in the missile silo for 15 days, before being launched on 9 February 1980.

On 2 August 1980, the first DF-4 test launch using the mobile launcher from a pre-surveyed surface launch spot was conducted successfully, achieving excellent accuracy. This was followed by a second test launch using the same launch method on 31 October of the same year.

Design Finalisation

The DF-4 completed design and manufacturing finalisation certification between 1980 and 1983, and the missile was officially type certified on 29 June 1983. The “512” warhead was type certified on 6 August 1988.

The whole DF-4 development programme took 18 years to complete due to political disruptions as well as changes in requirement and specification, including range extension and the change of launch method from underground silo to mobile launcher.

DF-31 Warhead Test Vehicle / CZ-1D

In 1997, a modified DF-4 missile equipped with a redesigned second-stage was used as the test vehicle for the new-generation nuclear warhead to be equipped by the DF-31 (CSS-9) ICBM. The redesigned DF-4 was later modified into the CZ-1D small-load orbital launch vehicle.

Deployment and Testing

The PLA Second Artillery Corps (SAC, now PLA Rocket Force) formed two DF-4 launch regiments as early as 1968, followed by the activation of the third launch regiment in 1970. However, the missile did not achieve initial operational capability until the late 1980s.

In late 1986, the PLA Second Artillery Corps conducted the first operational test launch of the DF-4 during a nuclear counterstrike exercise. A production variant DF-4 missile (Batch-03) carrying a dummy warhead was launched from Base 28 on 19 November 1986. It flew over a distance of 4,167 km before impacting its target zone in Xinjiang. The impact point was only 754 m away from its targeted spot in longitudinal and 310 m in horizontal, and the warhead detonated at an altitude only 0.78 m from its designed detonation altitude.

On 24 July 1992, another DF-4 batch-03 missile was fired from Base 28, also achieving excellent accuracy with under 250 m deviations in longitudinal and horizontal from the target spot.

The DF-4 Batch-04 production began in the mid-1990s and a test launch was successfully carried out in 1997.

On 28 August 2002, a SAC launch brigade launched a DF-4 from Base 28 after a long-distance manoeuvre from a different location.

In July 2004, a newly formed SAC launch brigade conducted a successful DF-4 test launch, followed by a second successful test launch using an extended service missile in 2005.

In November 2008, a SAC launch brigade fired a DF-4 missile, followed by a second launch in March 2009.

On 23 August 2017, the PLA Rocket Force (PLARAF) test launched a DF-4 from the Taiyuan Satellite Launch Centre (Base 25).1

The DF-4 remains in active service as of 2017, with 10—15 launchers deployed.

Design

The DF-4 is 29 m in length and 2.25 m in diameter, and has a gross launch mass of 82 t. The first stage of the missile uses four 255 kN-thrust YF-1 rocket motors placed in parallel, collectively known as the YF-2. The second-stage uses a single 320 kN YF-3 rocket motor. Both stages burn a storable liquid bi-propellant HNO3/UDMH. The missile uses a cascade compensation inertial guidance system, with an estimated CEP of 1,190 m. The missile carries a single 2,190 kg thermonuclear warhead with 3.3 MT yield for destruction of civilian population centres and large military complexes, but its accuracy is not sufficient for hitting point targets such as missile silos.

The DF-4 has been developed in two versions. In the silo version, the missile is stored vertically in an underground silo and raised to surface level before firing, much like the early U.S. Titans and Atlases. The fuelled missile can be stored inside the silos for up to 15 days prior to the firing. The cave-deployed version was designed to be stored horizontally in an underground tunnel, and rolled out on transporter-erector (TE) to a pre-surveyed launch spot immediately outside the mouth of the tunnel, where it is erected, fuelled, and fired.

Specifications

  • Overall length (m): 29
  • Core stage diameter (m): 2.25
  • Launch weight (kg): 82,000

Image Gallery

References

  1. The Diplomat. 2017. Chinese People’s Liberation Army Rocket Force Flight Tests Older DF-4 ICBM. [ONLINE] Available at: http://thediplomat.com/2017/08/chinese-peoples-liberation-army-rocket-force-flight-tests-older-df-4-icbm/. [Accessed 22 September 2017]. []

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