Chang Zheng     CZ-1  &  CZ-1D



The CZ-1 (Chang Zheng) was derived from the DF-4* missile (DF-3 with upper stage) which was added a solid fuel third stage. The CZ-1 launcher was 28 m  high for 77.4 tons at takeoff and could orbit a 0.300 tons payload at 440 km with 70° inclination. It launched the two first Chinese satellites from Juiquan in 1970 and 1971 after a failure in 1969.

"The DF-4 would use the DF-3 as the first stage and carry a 2,200 kg payload; it would have the same warhead as the DF-3 but with more heat-isulatoin material for higher reentry speeds. Its second-stage engine would be outfitted with a fiberglass-reinforced nozzle of large expansion ratio. R&D on the DF-4 started in March 1965. The first succesful flight of a redesigned DF-4 was on January 30, 1970. The first-stage lift-off thrust would be 104 tonnes and its second stage lengtened by 0.42 m in order to contain an additional two tonnes of  propellant. The missile range would be about 4,500 km."

CZ-1D is developed based on the DF-4A. It is a larger 3-stage launch vehicle with an orbit-maneuver solid motor (3-axis controlled by cold gas N2 thruster system).
It is dedicated for launching small satellites into Low Earth Orbit (LEO) and Sun-synchronous Orbit (SSO). The Launch Vehicle successfully conducted its first flight in Nov. 1997.

About the engines in the first and second stage of the rocket nothing is published up to now.

Meanwhile at first by Novosti Kosmonavtiki sensational photos of the Chinese engine YF-2 published. It is now confirmed that four single engines are combined with its own turbopumps. The shape of the chambers and the nozzles are more similar to the smaller Scud-B engine than to the Nodong engine. The Nodong engine has greater similarity to the Soviet four-chamber engine Isayev S2.1150 (Burya booster). In addition however clear differences between all engines are to be determined. In any case, this engine YF-2 (4 x YF-1) is a creation of Isayev's design bureau (codename 5D10). All the details are typical. The second stage powered by a single YF-3 engine, which was a high-altitude version of the YF-1 (?). Due to high temperature in tests, the initial use of titanium sheet for the nozzle was abandoned and hardened resin used finally. This engine also is used for the second stage of DF-4 missile. All engines uses the fuel combination UDMH/AK-27S.

Around the year 1997 the engine was replaced by the gimbaled
YF-40 engine with the fuel combination UDMH/N2O4. The new rocket is called CZ-2D, and also gets a new third stage.  It is an orbit-maneuver solid motor FG-36 with 3-axis controlled by cold N2 gas thruster system).

Changzheng 1 (CZ-1)


The CZ-1 was China’s first space launch vehicle. The rocket was based on the two-stage DF-4 liquid-propellant IRBM, added with a solid-rocket third-stage. The CZ-1 only made two launches, sending China’s first artificial satellite Dongfanghong 1 into the orbit on 24 April 1970, followed by the second satellite Shijian 1 on 3 March 1971.
The development of the CZ-1 was originally assigned to the Eighth Academy, with Wang Xi-ji being the chief designer. The programme was later reassigned to the First Academy (now China Academy of Launch Vehicle Technology, CALT), with Ren Xin-min being the chief designer.


The CZ-1 development was initiated in July 1965 in response to the demand for a rocket booster to launch China’s first satellite Dongfanghong 1 (Project 651). It was decided that the Shanghai Academy of Mechatronics (SAM) would be tasked with the development of the civilian rocket Changzheng 1, so that the First Academy could continue the development of the ballistic missiles. The CZ-1 design team was led by Wang Xi-ji, the deputy chief of the SAM.
With no previous experience in developing large rocket, the design team decided to base the space launch vehicle on the DF-4 liquid ICBM, which was under development at the First Academy. In order to achieve enough velocity to escape the Earth gravity, a solid rocket-powered third-stage would be added to the two-stage DF-4. This design would enable the rocket to send 300kg payload into 400km LEO inclined at 70°.
The Fourth Academy developed the GF-02 solid rocket motor with the ability to ignite at high altitude. The solid rocket motor was tested onboard the T-7A sounding rocket. Two launches were conducted in August 1968, both of which were successful. The test results showed that the rocket motor could be ignited at any altitude from less than 100km to 320km.
In November 1967, the National Defence Science & Technology Commission (NDSTC) decided to combine the DF-4 and CZ-1 programmes. The CZ-1 development was reassigned to the First Academy headed by Ren Xin-min. The First Academy was asked to speed up the development of the DF-4/CZ-1, with the aim to launch China’s first satellite in 1968.
The First Academy made some amendments to the original CZ-1 design. The modified design had a launch weight of 81.5 tonnes and a launch thrust of 104 tonnes. The rocket was 29.46m in length and 2.25m in diameter. The first- and second-stage of the launch vehicle were completely identical to those of the DF-4. The third-stage was fitted with its own flight control for the gliding stage of the flight. The fuel mass was increased from 900kg to 1,800kg. The original inertial guidance on the third-stage was replaced by a simpler spin-stabilisation. Explosive charges were adopted for the separation of the second- and third-stage and the jettison of the payload fairing to improve reliability. The third-stage was also added with a primitive telemetry system.
The DF-4/CZ-1 development was interrupted by the political turmoil during the Culture Revolution in the late 1960s. The missile was not ready for flight test until 1969. The batch-01 produced in 1969 included 7 two-stage flight test examples and 2 three-stage space launch vehicles.
Following two unsuccessful attempts in late 1969, the first depressed trajectory flight test of the DF-4 was conducted from the Jiuquan Satellite Launch Centre on 30 January 1970. The two stages of the missile separated and the second-stage ignited successfully as scheduled, and the warhead hit the target spot with high accuracy. The success of the test flight paved the way for the maiden flight of the CZ-1 to send China's first satellite into space.

In 1969, the First Academy proposed an improved model CZ-1A, which featured a newly-designed liquid-propellant, three-axis stabilised, fully-guided third-stage to give greater payload capacity and orbit insertion accuracy. The launch vehicle would be used to launch the Dengta 1 navigation satellite and the Shijian 2 scientific satellite. However, the project did not go ahead.
Two further improved variants, designated CZ-1B and CZ-1C, were proposed in the late 1970s, but neither had entered the engineering development stage.
In the 1990s, CALT introduced the CZ-1D as a small-life launch system for the commercial space launch market. The launch vehicle featured redesigned second- and third-stage for improved reliability and greater payload capacity (800~1,000kg to 200km LEO, or 350kg to 900km SSO). It made a successful maiden flight in November 1997, but hasn't flown since then.

The first- and second-stage of the CZ-1 were designed by the First Academy based on the DF-4 IRBM, and were built by 211 Plant situated in south suburb of Beijing. Both stages used a liquid bipropellant, with unsymmetrical dimethylhydrazine (UDMH) as fuel and nitric acid (HNO3) as an oxidiser.
The first-stage of the rocket was powered by an YF-2 liquid rocket engine, which consisted of four parallel YF-1 chamber motors.
The second-stage was powered by a single YF-3 liquid rocket engine, which was a high-altitude version of the YF-1 (?) capable of working in a vacuum environment. Development began in 1965 and completed in 1968.
The third-stage was powered by a GF-02 solid rocket motor developed by the Fourth Academy in Inner Mongolia. Development began in April 1967 and the motor was successfully tested in late 1969.
The airframe of the CZ-1 consisted of payload fairing, telemetry instrument compartment, flight control instrument compartment, four propellant tanks, two inter-stage sections, heat-resistant fuel tank bottoms and fuel/gas pipelines.
The CZ-1 adopted a “hot” inter-stage separation, where the adjacent stages were separated by the impingement of the hot exhaust gas jet from the engine of the ongoing stage. The engine of the second-stage ignited when the two stages were still connected together, thus, eliminating the need for jettisoning devices to provide the separation impulse and considerably reducing the none control duration during the separation. A fibreglass heat insulation layer is added on the top of the first-stage tank to prevent damage due to the high pressure and hot stream of engine exhaust from the upper stage.
The addition of the third-stage increased the length-diameter ratio of the CZ-1 to 13.27, which had weakened the rocket’s structural strength. To reduce the rocket’s length as much as possible, the fuel and the oxidiser tanks were combined into a single tank divided by a floor structure. The second-stage motor was also direct mounted to the lower part of the propellant tank, so that the tank formed part of the stage’s thrust and weight bearing load structure. The two modifications had shortened the rocket’s overall length by 2m.
The CZ-1 used a cascade compensation inertial guidance system, similar to that of the DF-4. As the rocket needed to fly powerlessly for 280 seconds before the ignition of the third-stage engine, a flight control system was added using pressurised nitrogen gas to maintain the course of its flight.
The third-stage of the launch vehicle was unguided, using spin-stabilisation to maintain its flight course. It relied on a timing device to generate signals for initialising the spin and satellite separation.

Changzheng 1D (CZ-1D)

The CZ-1D was introduced by CALT in the late 1990s as a small-lift launch vehicle for the commercial space launch market. The launch vehicle was based on a specially modified DF-4. The vehicle made its first successful flight on 1 November 1997, but has never flown for a satellite launch mission.
The CZ-1D was capable of sending 1,000 kg payload to a 200km LEO inclined at 28.5°, or 350 kg payload to a 900km SSO. The increased payload and accuracy was achieved by employing a N2O4/UDMH second-stage, and a 3-axis stabilised solid third-stage.

The first-stage was powered by an YF-2A  liquid rocket engine, which was an improved version of the original YF-2 on the CZ-1. The sea-level thrust was increased by 81.2 kN, and the sea-level Isp was increased to 2,378 N.s/kg.
On the original design, the second-stage of the CZ-1D was to be powered by two parallel YF-40 engines burning the N2O4/UDMH propellant.
The propulsion of the third-stage consisted of a FG-36 solid rocket engine and a DaFY2-1 auxiliary engine. The solid engine used the HTPB solid propellant, with 645 kg propellant carried onboard. The auxiliary engine, which used the N2O4/UDMH propellant, was designed to maintain the course of flight during the gliding stage. The engine consisted of four 1.2 kN/1.6 kN chamber motors and twelve 25 N chamber motors, located on the third-stage symmetrically.
The CZ-1D shared the same (?) airframe design in its first- and second-stage with the original CZ-1. The diameter of the third-stage was increased from 1.5m to 2.05m. The original cone-shaped inter-stage section between the second- and third-stage was replaced by a cylinder-shaped design, which also accommodated the main and auxiliary thrusters of the third-stage.

The CZ-1D had adopted a platform-computer inertial guidance system, which allowed the third-stage of the rocket to be 3-axis stabilised.