RD-120
| Country of origin | USSR/Russia |
|---|---|
| Designer | NPO Energomash, V.K.Chvanov, V.P. Radovsky |
| Manufacturer | Yuzhmash |
| Application | Upper stage |
| Status | Operational |
| Liquid-fuel engine | |
| Propellant | LOX / RG-1 |
| Cycle | Staged combustion cycle (rocket) |
| Performance | |
| Thrust (vac.) |
Standard: 834 kN (187,000 lbf) |
| Thrust-to-weight ratio |
Standard: 75.55 |
| Chamber pressure |
Standard: 162.8 bar (16.28 MPa) |
| Isp (vac.) | 350 s (3.4 km/s) |
| Burn time | 315 seconds |
| Dimensions | |
| Length | 3.87 m (12.7 ft) |
| Diameter | 1.95 m (6.4 ft) |
| Dry weight | 1,125 kg (2,480 lb) |
| Used in | |
| Zenit-2, Zenit-3SL | |
| References | |
| References | |
Standard: 834 kN (187,000 lbf)
Standard: 75.55
Standard: 162.8 bar (16.28 MPa)
The RD-120 (GRAU Index 11D123) is a liquid upper stage rocket engine burning RG-1 and LOX in an oxidizer rich staged combustion cycle with an O/F ratio of 2.6. It is used in the second stage of the Zenit family of launch vehicles. It has a single, fixed combustion chamber and thus on the Zenit it is paired with the RD-8 vernier engine. The engine has been developed from 1976 to 1985 by NPO Energomash with V.P. Radovskogo leading the development. It is manufactured by Yuzhmash in Ukraine along with most of the rocket.
It should not be confused with the RD-0120, which is a discontinued LOX/hydrogen rocket engine that was used in the Soviet Energia launch system.
During the Buran programme initial development of the 11D77 —the launch vehicle later known as Zenit—, KBKhA had been assigned the development of the second stage engine, as they had done for the Proton and Soyuz vehicles. But given the difficulties for NPO Energomash in developing the RD-123 (which would later be known as the RD-170), they ceded the hydrogen / oxygen sustainer engine development to KBKhA. This project, the analog of the SSME, was project RD-130 within NPO Energomash. But when KBKhA tackled the development, named it RD-0120, a name that is always a source of confusion with the engine of the current article. In exchange for them tackling the difficult development of the cryogenic propellant engine, Energomash assumed the responsibility of developing the second stage engine of the 11D77, which would eventually be known as the RD-120. The fact that the RD-120 and the RD-0120 had this intertwined conception, within the same program, and with a swap of designer bureaus, does not help to avoid the confusion.
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