| RD-253 | |
| Country Of Origin: | |
| First Date: | RD-253: 1965 RD-275: 1995 RD-275М: 2007 |
| Designer: | NPO Energomash, Valentin Glushko |
| Manufacturer: | Proton-PM |
| Purpose: | First stage booster |
| Associated: | Proton |
| Successor: | RD-254, RD-256, RD-275, RD-275М |
| Status: | Operational |
| Type: | liquid |
| Fuel: | UDMH |
| Mixture Ratio: | 2.67 |
| Cycle: | Staged combustion |
| Combustion Chamber: | 1 |
| Nozzle Ratio: | 26.2 |
| Thrust(Vac): | RD-253: RD-275: RD-275М: |
| Thrust(Sl): | RD-253: RD-275: RD-275М: |
| Thrust To Weight: | 156.2 |
| Chamber Pressure: | RD-253: RD-275: RD-275M: |
| Specific Impulse Vacuum: | RD-253: 316s RD-275: 316s RD-275M: 315.8s |
| Specific Impulse Sea Level: | RD-253: 285s RD-275: 287s RD-275M: 288s |
| Gimbal: | 7.5°, single plane |
| Dry Weight: | RD-253: RD-275: RD-275M: |
The RD-253 and its later variants, the RD-275 and RD-275M, are liquid-propellant rocket engines developed in the Soviet Union by Energomash. The engines are used on the first stage of the Proton launch vehicle and use an oxidizer-rich staged combustion cycle to power the turbopumps. The engine burns UDMH/N2O4, which are highly toxic but hypergolic and storable at room temperature, simplifying the engine's design.
Development of the RD-253 started in 1961. Preliminary investigations and development of the engine and its further production was performed under the guidance of Valentin Glushko and finished in 1963. The RD-253 uses an oxidiser-rich staged combustion cycle. It was used for the first time in July 1965, when six engines powered the first stage of the Proton 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 one of the most reliable engines in the USSR and modern Russia.
As the first stage of the Proton-K rocket used six RD-253 engines, the system played a pivotal role in Russian space missions when this rocket was chosen as a carrier, including the following programs: "Luna", "Venera", "Mars probe", crewed orbital stations "Salyut", "Mir", and it launched several principal modules for ISS. It was widely used for the launches of heavy satellites. The last RD-253 rocket engine was used on a Proton-K rocket and launched on March 30, 2012.
Since the original development of the engine, several modifications were designed that were not flown. One of them was the RD-256 engine, for which development stopped on experimental models. It was not used in flights and was designed for a cancelled vehicle. The RD-254 variant was supplied with an extended nozzle for use in vacuum.
All rights to sell and employ the RD-253 for Proton rocket are held by Energomash which produces it in Perm, Russia.
The modification RD-275 (14D14) appeared as the result of development in 1987–1993, with the purpose to achieve a more powerful version of the engine. Its 7.7% higher thrust was reached by raising pressure in the combustion chamber and enabled an increase of payload mass to geostationary orbit (GEO) up to more than 6000kg (13,000lb). 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 has 5.2% higher thrust and has the designation 14D14M (RD-275M). It was designed to allow the rocket to deliver 150kg (330lb) 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-275M with a total time of 735s. In the middle of 2005, this engine went into production by government commission. The first launch of a Proton-M with 14D14M engines was launched on July 7, 2007.
The final version RD-275M is sometimes designated as RD-276, but through 2009 the name RD-275M (14D14M) was more common. 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.
During the years there have been many versions of this engine:
| Engine | RD-220 | RD-221 | RD-222 | RD-223 | RD-253 | RD-253F | RD-254 | RD-275 | RD-275M | |
|---|---|---|---|---|---|---|---|---|---|---|
| Development | 1960 | 1960-1961 | 1962-1966 | 1966-1967 | 1961-1963 | 1987-1993 | 2001-2005 | |||
| Combustion Chamber Pressure | 14.7MPa | 16.9MPa | 14.7MPa | 15.7MPa | 16.5MPa | |||||
| Thrust (Vacuum) | 1074kN | 1120kN | 1634kN | 1700kN | 1635kN | 1870kN | 1720kN | 1750kN | 1832kN | |
| Thrust (Sea Level) | 947kN | N/A | 1471kN | N/A | 1474kN | 1720kN | N/A | 1590kN | 1671kN | |
| Specific Impulse (Vacuum) | 306isp | 318isp | 302isp | 314isp | 316isp | 317isp | 328isp | 316isp | 315.8isp | |
| Specific Impulse (Sea Level) | 270isp | N/A | 272isp | N/A | 285isp | 290isp | N/A | 287isp | 288isp | |
| Height | 2600mm | 4200mm | 3470mm | 5050mm | 3000mm | 2700mm | 4000mm | 3050mm | 3050mm | |
| Diameter | 1300mm | 2400mm | 1460mm | 2530mm | 1500mm | 1490mm | 2600mm | 1500mm | 1500mm | |
| Intended Use | N-1 first stage | N-1 second stage | N-1 first stage | N-1 second stage | Proton (8K62) first stage | R-36M (15А14) first stage | UR-700 third stage, Proton and N-1 second stages | Proton-M first stage | Proton-M first stage | |
| Status | Project (Abandoned) | Retired | Project (Abandoned) | Retired | In Production | |||||