The YF-73 was China's first successful

cryogenic In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held in Washington, DC in 1971) endorsed a univers ...

liquid hydrogen Liquid hydrogen () is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecule, molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point (thermodynamics), critical point of 33 Kelvins, ...

fuel and

liquid oxygen Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing. Physical ...

oxidizer gimballed engine. It was used on the

Long March 3 The Long March 3 (), also known as the Changzheng 3, CZ-3 and LM-3, was a Chinese orbital carrier rocket design. They were all launched from Launch Area 3 at the Xichang Satellite Launch Center. It was a three-stage rocket, and was mostly used ...

H8 third stage, running on the simple

gas generator A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical. The term often refers to a device that uses a ...

cycle and with a thrust of . It had four hinge mounted nozzles that gimbaled each on one axis to supply thrust vector control and was restart capable. It used cavitating flow venturis to regulate propellant flows. The gas generator also incorporated dual heat exchangers that heated hydrogen gas, and supplied helium from separate systems to pressurize the hydrogen and oxygen tanks. The engine was relatively underpowered for its task and the start up and restart procedures were unreliable. Thus, it was quickly replaced by the

YF-75 The YF-75 is a liquid cryogenic rocket engine burning liquid hydrogen and liquid oxygen in a gas generator cycle. It is China's second generation of cryogenic propellant engine, after the YF-73, which it replaced. It is used in a dual engine mou ...

History

In October 1970 the Beijing Aerospace Propulsion Institute was tasked with developing a prototype rocket engine burning liquid hydrogen and liquid oxygen. They settled on a pump-fed gas generator design. The prototype was successfully fire tested for 20 seconds on January 25, 1975. In March of the same year, China officially initiated the ''Project 311'' do initiate the engineering work on the first Chinese cryogenic engine, which was named YF-73. It had its debut on April 8, 1984, when it sent the first geosynchronous communications satellite experiment, the Dong Fang Hong 2 to geosynchronous orbit. It flew 13 times with 3 failures and was last used on May 26, 2000. It was replaced by the more capable YF-75 which enabled to increase payload from to over and significantly increased reliability.

References

External links

Encyclopedia Astronautica

Rocket engines using hydrogen propellant Rocket engines of China Rocket engines using the gas-generator cycle {{rocket-stub