YF-90

The YF-90 is a liquid cryogenic rocket engine burning liquid hydrogen and liquid oxygen in a staged combustion cycle. It is China's first hydrogen-oxygen engine to use the staged combustion cycle and is expected to be used for the second stage of the Long March 9, which is a three-stage rocket with boosters.^[4][5] The engine has advanced features such as variable thrust, multiple ignitions, and automatic fault diagnosis.^[2]

YF-90

Country of origin	China
Associated LV	Long March 9
Predecessor	YF-77
Status	In development
Liquid-fuel engine
Propellant	Liquid oxygen / Liquid hydrogen
Mixture ratio	6.0 (±5%) Variable
Cycle	Staged combustion cycle
Pumps	2
Configuration
Nozzle ratio	100
Performance
Thrust, vacuum	2,200 kilonewtons (490,000 lbf)
Thrust-to-weight ratio	46.7
Specific impulse, vacuum	453 seconds (4.44 km/s)
Dimensions
Length	6.1 metres (20 ft) (With Engine Mount)
Diameter	2.87 metres (9 ft 5 in)
Dry mass	4,800 kilograms (10,600 lb)
References
References	[1][2][3]

History

On July 28, 2021, the engine's manufacturer, China Aerospace Science and Technology Corporation (CASC) completed the first YF-90 engineering prototype.^[6]

On September 23, 2021, the engine successfully underwent its first semi-system test.^[7][8] The YF -90 engine is one of the key technologies for China's deep space exploration ambitions.^[9]

In 2023, CASC plans to conduct more tests on the YF-90 engine, as well as on its first-stage counterpart, the YF-130 engine. The YF-130 is a liquid kerosene-oxygen rocket engine with a thrust of 500 tonnes. Both engines are expected to be ready for flight by 2025.^[9]

On December 17, 2024, the engine successfully underwent its first full system test.^[10]