|Country of origin||USSR/Russia|
|Designer||V.Glushko, OAO «Proton-PM», Perm, Russia|
|Successor||RD-254; RD-256; RD-275; RD-275М (RD-276)|
|Propellant||N2O4 / UDMH|
|Thrust (vac.)||366,439-411,400 lbf (1.63-1.83 MN)|
|Thrust (SL)||330,469-375,431 lbf (1.47-1.67 MN)|
|Chamber pressure||2,200-2,450 psi (15-16.9 MPa)|
|Isp (vac.)||316 s|
|Isp (SL)||285 s|
|Length||120 in (3,000 mm)|
|Diameter||59 in (1,500 mm)|
|Dry weight||2,800 lb (1,260 kg)|
|1-st stage of Proton rocket|
RD-253 (Russian: Раке́тный дви́гатель 253, Rocket Engine 253) - liquid-fuel rocket engine developed by Energomash, Russia. It is used on first stages of the Proton rocket. The RD-253 is the first non-cryogenic engine in the world that uses staged combustion afterburning of oxidizer-rich hot turbine gas. This bipropellant engine is designed to use the toxic propellant combination of UDMH/N2O4 which causes ecological and financial problems during exploitation. But application of high-boiling hypergolic propellant makes RD-253 more simple, safe and cheap, outweighing the negative aspects of its design.
Development of RD-253 started in 1961. Preliminary investigations and development of the engine as well as its further production was performed under the guidance of Valentin Glushko and finished in 1963. The RD-253 uses a staged combustion cycle for oxidizer-rich generator gas. It was used for the first time in July 1965 year when six engines powered the first stage of the rocket. Development and production of RD-253 was a qualitative leap forward for rocketry of that time by achieving high levels of thrust, specific impulse and pressure in the combustion chamber. This engine is used to be one of the most reliable engines in the USSR and modern Russia.
As every first stage of Proton rockets uses six RD-253 engines it was a pivotal part in every Russian space missions when this rocket was chosen as carrier, including the following programs: "Luna", "Venera", "Mars probe", manned orbital stations "Salyut", "Mir" and it supplied several principal modules for ISS. It is used widely also for heavy satellites launches.
Since the original development of the engine, several modifications were designed that weren't used in rockets. One of them was the RD-256 engine for which development stopped on experimental models. It wasn't used in flights and was designed for a cancelled vehicle. The modification marked RD-254 was supplied with extended nozzle for work in vacuum.
Current state and development
The modification RD-275 (14D14) appeared as the result of development in 1987–1993 years with the purpose to achieve a more powerful version of the engine. Its 7.7% higher thrust was reached by raising pressure in combustion chamber and enabled to raise payload mass to geostationary orbit (GEO) up to more than 600 kg (1,300 lb). The successful maiden flight of a Proton rocket with the new engine was completed in 1995.
Energomash started the development of next more powerful version of engine in 2001. It will have 5.2% higher thrust and has the designation 14D14M (RD-275M). It is designed to allow the rocket to deliver 150 kg (330 lb) more payload to GEO.
In the period from 2002 to 2003 years some experimental work was completed with this version of the engine. It included four test firings of three experimental RD-275Ms with a total time of 735 s. In the middle of 2005 this engine went into production by government commission.
As a final note, it is to be mentioned that the final version RD-275M is sometimes designated as RD-276 but to date 2009 the name RD-275M (14D14M) has been more common. Also some sources points out the cost of production per engine as much as 1.5 million USD and sometimes calls some lower figures around 1 million USD per unit.
- Data shown here is attributed to primal RD-253 and its later modifications and based on information of manufacturer (Rocket engine RD-253). (in russian)