YF-77
| Country of origin | China |
|---|---|
| First flight | Long March 5 inaugural flight (2016-11-03) |
| Designer | Academy of Aerospace Liquid Propulsion Technology |
| Application | sustainer engine |
| Associated LV | Long March 5 |
| Status | In service |
| Liquid-fuel engine | |
| Propellant | Liquid oxygen / Liquid hydrogen |
| Mixture ratio | 5.5 (adjustable) |
| Cycle | Gas-generator |
| Configuration | |
| Chamber | 1 |
| Nozzle ratio | 49 |
| Performance | |
| Thrust, vacuum | 700 kN (160,000 lbf) |
| Thrust, sea-level | 518 kN (116,000 lbf) |
| Chamber pressure | 10.1 MPa (1,460 psi) |
| Specific impulse, vacuum | 428.0 seconds (4.197 km/s) |
| Specific impulse, sea-level | 316.7 seconds (3.106 km/s) |
| Burn time | 525 seconds (8.75 min) |
| Dimensions | |
| Length | 2,600 mm (100 in) (with rack) |
| Diameter | 1,500 mm (59 in) |
| Used in | |
| Long March 5 core stage. | |
| References | |
| References | |
The YF-77 is China's first cryogenic rocket engine developed for booster applications. It burns liquid hydrogen fuel and liquid oxygen oxidizer using a gas generator cycle. A pair of these engines powers the LM-5 core stage. Each engine can independently gimbal in two planes. Although the YF-77 is ignited prior to liftoff, the LM-5's four strap-on boosters provide most of the initial thrust in an arrangement similar to the European Vulcain on the Ariane 5 or the Japanese LE-7 on the H-II.