RD-855
| Country of origin | Soviet Union |
|---|---|
| First flight | December 16, 1965 |
| Last flight | January 30, 2009 |
| Designer | Yuzhnoye Design Bureau |
| Manufacturer | Yuzhmash |
| Application | Vernier |
| AssociatedLV | R-36,Tsyklon-2andTsyklon-3 |
| Status | Out of production |
| Liquid-fuel engine | |
| Propellant | N2O4/UDMH |
| Mixture ratio | 1.97 |
| Cycle | Gas generator |
| Configuration | |
| Chamber | 4 |
| Performance | |
| Thrust, vacuum | 328 kN (74,000 lbf) |
| Thrust, sea-level | 285.4 kN (64,200 lbf) |
| Chamberpressure | 6.570 MPa (952.9 psi) |
| Specific impulse,vacuum | 292 s (2.86 km/s) |
| Specific impulse,sea-level | 254 s (2.49 km/s) |
| Burn time | Up to 127s |
| Restarts | 1 |
| Gimbal range | ±41° |
| Dimensions | |
| Length | 1.74 m (5 ft 9 in) |
| Diameter | 3.81 m (12.5 ft) |
| Dry mass | 320 kg (710 lb) |
| Used in | |
| R-36,Tsyklon-2andTsyklon-3first stage vernier | |
| References | |
| References | [1][2][3] |
TheRD-855(GRAUIndex8D68M), also known as theRD-68M,is aliquid-fueledrocket enginewith fournozzles.As avernier engine,it provides fine steering adjustments for rockets. It is powered by a combination ofN2O4,an oxidizer, andUDMH,a propellant.[2]This combination is hypergolic, meaning the two substances ignite on contact, eliminating the need for an external ignition source.
The RD-855 can orient its chambers within a range of ±42° using hydraulic cylinders.[2]Each chamber on the Tsyklon rockets is protected by an aerodynamic cover, and these covers are equipped with small retro-rockets allowing for separation from the second stage.[2]
The RD-855 utilizes thegas generator cycle,in which a portion of the propellant is burned in a pre-burner to produce hot gases that drive the engine's turbopumps, and then the gases are discarded without passing through the main combustion chamber.
It played a key role in rockets such as theR-36,Tsyklon-2,andTsyklon-3,steering these rockets byadjusting its nozzles.[3]The engine is housed in a cylindrical structure that surrounds the primaryRD-251engine. This arrangement provides protection for the nozzles and ensures the successful detachment of the rocket's first stage.[2]The RD-855 is activated two seconds before the main RD-251 engine.[2]
Manufactured from 1965 to 1992, the RD-855's inaugural flight was on December 16, 1965, aboard theR-36missile. Its most recent known flight was on January 30, 2009, with theTsyklon-3.Although there were plans to restart its production for theTsyklon-4,the engine remains out of production following the potential discontinuation of the program.[4]
See also
[edit]- R-36– TheSovietICBMfor which the RD-855 was created.
- Tsyklon-2– ASovietsmall rocket that uses the RD-855.
- Tsyklon-3– ASovietsmall rocket that uses the RD-855.
- Tsyklon-4– AUkrainiansmall rocket project that would have used the RD-855.
- Yuzhnoe Design Bureau– The RD-855 designer bureau.
References
[edit]- ^"RD-855".Encyclopedia Astronautica.Archived fromthe originalon April 30, 2002.Retrieved2016-07-06.
- ^abcdefPillet, Nicolas."Tsiklone - Le premier étage"[Tsyklon - The first stage] (in French). Kosmonavtika.Retrieved2016-07-06.
- ^ab"RD-855".Yuzhnoye. Archived fromthe originalon 29 May 2015.
- ^Krebs, Gunter Dirk (2016-04-24)."Tsiklon".Gunter's Space Page.Retrieved2016-07-05.
External links
[edit]- Yuzhnoye Design Bureau English-language home pageArchived2021-06-29 at theWayback Machine
- Yuzhmash Home Page
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