RD-215
# RD-215

The RD-215 (GRAU Index 8D513) was a dual nozzle liquid rocket engine, burning AK-27 (a mixture of 73% nitric acid and 27% $N_2O_4$ + iodine passivant) and UDMH. It was used in a module of two engines (four nozzles) known as the RD-216 (GRAU Index 8D514). The RD-215 was developed by OKB-456 for Yangel's Yuzhmash R-14 (8K65) ballistic missile. Its variations were also used on the Kosmos-1, Kosmos-3 and Kosmos-3M launch vehicles.

## Versions

The family incorporate many versions:

* RD-215: GRAU Index 8D513. Original design for the R-14 (8K65). Used also on the Kosmos-1 and Kosmos-3
* RD-215U: GRAU Index 8D513U. Improved engine for the R-14U (8K65U).
* RD-215M: GRAU Index 8D513M. Improved version used on the Kosmos-3M.
* RD-217: GRAU Index 8D515. Modified design for the R-16 (8K64) first stage.
* RD-219: GRAU Index 8D713. Modified design for the R-16 (8K64) second stage.

## Modules

These engines were bundled into modules of pairs of engines. The serial production modules were:

* RD-216: GRAU Index 8D514. Bundle of two RD-215, used on the R-14 (8K65), Kosmos-1 and Kosmos-3 first stage.
* RD-216U: GRAU Index 8D514U. Bundle of two RD-215U, used on the R-14U (8K65U) first stage.
* RD-216M: GRAU Index 8D514M. Bundle of two RD-215M, used on the Kosmos-3M first stage.
* RD-218: GRAU Index 8D712. Bundle of three RD-217, powers the R-16 (8K64) first stage.

RD-215 Family of Engines :

| Engine | RD-215 | RD-215U | RD-215M |
| - | - | - | - |
| GRAU | 8D514 | 8D514U | 8D514M |
| Development | 1958-1960 | 1960-1961 | 1966-1968 |
| Propellant | AK-27I (73% nitric acid, 27% $N_2O_4,$ and iodine passivant) / UDMH | AK-27I (73% nitric acid, 27% $N_2O_4,$ and iodine passivant) / UDMH | AK-27I (73% nitric acid, 27% $N_2O_4,$ and iodine passivant) / UDMH |
| Combustion chamber pressure | 7.355 MPa (1,066.8 psi) | 7.355 MPa (1,066.8 psi) | 7.355 MPa (1,066.8 psi) |
| Thrust, vacuum | 887 kN (199,000 lbf) | 887 kN (199,000 lbf) | 890 kN (200,000 lbf) |
| Thrust, sea level | 740 kN (170,000 lbf) | 740 kN (170,000 lbf) | 742.8 kN (167,000 lbf) |
| $I_{sp},$ vacuum | 289 s (2.83 km/s) | 289 s (2.83 km/s) | 291.3 s (2.857 km/s) |
| $I_{sp},$ sea level | 246 s (2.41 km/s) | 246 s (2.41 km/s) | 248 s (2.43 km/s) |
| Burn time | 146s | N/A | N/A |
| Length | 2,205 mm (86.8 in) | 2,205 mm (86.8 in) | 2,205 mm (86.8 in) |
| Diameter | 2,260 mm (89 in) | 2,260 mm (89 in) | 2,260 mm (89 in) |
| Dry weight | 575 kg (1,268 lb) | 575 kg (1,268 lb) | 570 kg (1,260 lb) |
| Use | R-14 (8K65), Kosmos-1 and Kosmos-3 | R-14U (8K65U) | Kosmos-3M |
