YF-75
Country of origin | Gas-generator |
---|---|
Configuration | |
Chamber | 1 |
Nozzle ratio | 80 |
Performance | |
Thrust, vacuum | 78.45 kilonewtons (17,640 lbf) |
Chamber pressure | 3.76 MPa (37.6 bar) |
Specific impulse, vacuum | 438 seconds (4.30 km/s) |
Burn time | 470 seconds (7.8 min) |
Dimensions | |
Length | 2.8 metres (9 ft 2 in) |
Diameter | 1.5 metres (4 ft 11 in) |
Dry weight | 550 kilograms (1,210 lb) |
Used in | |
Long March 3A, Long March 3B and Long March 3C H-18 third stage. | |
References | |
References | [1][2][3][4] |
The YF-75 is a
Development
Given the upward trend on geosynchronous communication satellite's mass and size, a program to develop an engine more powerful than the YF-73 was started by 1982.[2] The proper development of the engine started in 1986 and leveraged the experience of the YF-73.[5] It flew for the first time in 1994. By September 2013, it had accumulated 12 start up and 3,000 seconds of firing time without malfunction.[2]
By 2006 and with the project for the Long March 5 family a serious redesign program was started. The resulting engine, the YF-75D is a different engine, using a closed circuit expander cycle like the RL10.
Technical Description
The combustion chamber
The turbopumps use solid propellant cartridge for start up, while the gas generator and combustion chamber use pyrotechnic igniter. It can restart for two burn profile missions.[2] All subsystems are attached to the combustion chamber and gimbal is achieved by rotating the whole engine on two orthogonal planes with two independent actuators. These actuators use high pressure hydrogen as hydraulic fluid.[5] The oxygen supply system has a propellant utilization valve before the main LOX valve to regulate its flow and thus variate the mixture ratio. This enables optimization of the propellant reserves and improves performance.[4]
References
- ^ "YF-75". Encyclopedia Astronautica. Archived from the original on 2013-06-05. Retrieved 2015-07-08.
- ^ a b c d e Nan, Zhang (2013-09-23). "The Development of LOX/LH2 Engine in China" (pdf). 64rd International Astronautical Congress, Beijing, China. IAC-13-C4.1 (1x18525). International Astronautical Federation: 5. Retrieved 2015-07-08.
- ^ "Long March". Rocket and Space Technology. Retrieved 2015-07-08.
- ^ a b c d LM-3A Series Launch Vehicle User's Manual. Issue 2011 (PDF). CASC. Retrieved 2015-07-08.
- ^ ISBN 978-1563476495.