S5.98M
| Country of origin | Russia | 
|---|---|
| First flight | 1990-11-20 | 
| Manufacturer | KB KhIMMASH | 
| Application | Upper Stage | 
| Associated LV | Proton-M and Rokot | 
| Predecessor | S5.92 | 
| Status | In Production | 
| Liquid-fuel engine | |
| Propellant | N2O4 / UDMH | 
| Mixture ratio | 2.0 | 
| Cycle | Gas Generator | 
| Configuration | |
| Chamber | 1 | 
| Performance | |
| Thrust, vacuum | 19.62 kilonewtons (4,410 lbf) | 
| Chamber pressure | 9.8 megapascals (1,420 psi) | 
| Specific impulse, vacuum | 328.6 seconds | 
| Burn time | 3,200 seconds | 
| Restarts | 7 | 
| Dimensions | |
| Length | 1,150 millimetres (45 in) | 
| Diameter | 948 millimetres (37.3 in) | 
| Dry mass | 95 kilograms (209 lb) | 
| Used in | |
| Briz-M and Rokot | |
| References | |
| References | |
The S5.98M, also known as the 14D30, is a Russian rocket engine, currently powering the Briz upper stages. It was designed by KB KhIMMASH, the famous Isaev designed bureau. It burns a hypergolic mixture of unsymmetrical dimethylhydrazine (UDMH) fuel with dinitrogen tetroxide (N2O4) oxidizer in a gas-generator cycle.