| Country of origin | Soviet Union |
|---|---|
| First flight | December 16, 1965 |
| Last flight | January 30, 2009 |
| Designer | Yuzhnoye Design Bureau |
| Manufacturer | Yuzhmash |
| Application | Vernier |
| Associated LV | R-36, Tsyklon-2 and Tsyklon-3 |
| Status | Out of production |
| Liquid-fuel engine | |
| Propellant | N2O4 / UDMH |
| Mixture ratio | 1.98 |
| Cycle | Gas generator |
| Configuration | |
| Chamber | 4 |
| Performance | |
| Thrust, vacuum | 54.23 kN (12,190 lbf) |
| Chamber pressure | 7.160 MPa (1,038.5 psi) |
| Specific impulse, vacuum | 280.5 s (2.751 km/s) |
| Burn time | Up to 163 s |
| Restarts | 1 |
| Gimbal range | ±30° |
| Dimensions | |
| Length | 0.9 m (2 ft 11 in) |
| Diameter | 3.35 m (11.0 ft) |
| Dry mass | 112.5 kg (248 lb) |
| Used in | |
| R-36, Tsyklon-2 and Tsyklon-3 second stage vernier | |
| References | |
| References | [1][2][3] |
The RD-856 (GRAU Index 8D69M), also known as the RD-69M, is a four-nozzle liquid-fuel rocket vernier engine, burning N2O4 and UDMH in a gas generator cycle.[3] It was used on the R-36, Tsyklon-2 and Tsyklon-3 second stage as thrust vector control by gimbaling of its nozzle.[3] The engine is distributed through a cylindrical structure that is integrated around the main engine RD-252 module. The structure includes aerodynamic protection for the nozzles.[2] The engine was started by a pyrotechnic ignitor.[2]
The engine was serially produced between 1965 and 1992. It was first launched on December 16, 1965 on an R-36 and its last launch was on January 30, 2009 with the last launch of the Tsyklon-3. The production capability was restarted for the Tsyklon-4 but with the apparent cancellation of the program the engine would still be out of production.[4]
ea-rd856 was invoked but never defined (see the help page).kosmo-tsiklone3 was invoked but never defined (see the help page).yuzhnoye-rd856 was invoked but never defined (see the help page).gunter-tsiklon was invoked but never defined (see the help page).