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RD-191 (РД-191)
RD-191 MAKS2013.JPG
Country of originFlag of Russia.svg  Russia
Designer NPO Energomash
ManufacturerNPO Energomash / Proton-PM (in transition)
ApplicationMain engine
Predecessor RD-170
StatusIn use
Liquid-fuel engine
Propellant LOX / RP-1
Mixture ratio2.6
CycleOxidizer-rich staged combustion
Nozzle ratio37:1
Thrust (vac.)2.09 MN (470,000 lbf) at 100% throttle
Thrust (SL)1.92 MN (432,000 lbf) at 100% throttle
Throttle range27–105%
Thrust-to-weight ratio 89
Chamber pressure 25.8 MPa (3,740 psi)
Isp (vac.)337 s (3.30 km/s)
Isp (SL)310.7 s (3.047 km/s)
Burn time325 s (Angara A5 core stage)
Gimbal range
Length4 m (160 in)
Diameter1,45 m (57 in)
Dry weight2,290 kg (5,050 lb)
References [1] [2]

The RD-191 is a high-performance single-combustion chamber rocket engine, developed in Russia. It is derived from the RD-180 dual-combustion chamber engine, which itself was derived in turn from the four-chamber RD-170 originally used in the Energia launcher.


The RD-191 is fueled by a kerosene / LOX mixture and uses an oxygen-rich staged combustion cycle. In the future the engine is expected to become a workhorse in the Russian space sector, as older launch vehicles are phased out of production and service.


Burn ignition is provided chemically, by feeding a starter fluid into the combustion chamber and gas generator, which is self-igniting on contact with liquid oxygen. The engine is capable of throttling down to 30% of nominal thrust; the design also allows for a short-duration enhanced thrust (up to 105% of nominal level) in emergency situations. A Cardan suspension provides for yaw and pitch controls by gimballed thrust deflection up to 8 degrees.

A modern design, the engine incorporates sensors monitoring burn conditions. The measurements are used for telemetry and an emergency protection system.

The engine's powerhead fulfills two additional functions, heating helium gas for pressurization of propellant tanks and generating hydraulic power for hydraulic actuators to deflect the nozzle and aerodynamic rudders.


On 5 September 2008, the creator of the engine, NPO Energomash, stated that the engine had completed the full cycle of development and burn tests and is ready for manufacturing and delivery. [3] The primary launch vehicle utilizing this engine is the Angara rocket, currently being developed. [4]

As of 2010, the engine had passed all development phases, and its nine prototypes had accumulated over 23,000 seconds in 105 firing tests, with one of them reaching the maximum running time of 3,635 seconds in 12 tests. Interdepartmental tests are under way, and manufacturing of the engines for flight development tests has started. The flight tests will begin with a launch of the Angara-1.2 light-class rocket, and then of the Angara-A5 heavy launcher. Despite problems with funding, work on the RD-191 engine is in line with the Angara rocket family's master schedule. [5]



A version of the RD-191 with thrust reduced to 170 tonnes, called RD-151, was fire-tested on 30 July 2009. The first flight test of this engine was conducted on 25 August 2009 as part of the first launch of South Korean Naro-1 rocket. [6] [7]


The RD-181 is based on the RD-191 and is adapted for integration on the Antares rocket. While the RD-193 was designed as a close replacement for the NK-33, on 17 December 2014, Orbital Sciences announced that it would use the NPO Energomash RD-181 on the version 2 Antares launch vehicle and had contracted directly with NPO Energomash for up to 20 RD-181 engines. [8] Two engines are used on the first stage of each Antares, which is currently used to carry cargo to the International Space Station under contract to NASA. [9] While Russian press had stated that the contract was valued at US$ 1 billion with options, Orbital stated on 26 January 2015 that even when exercising all the options the contract was less than that amount, and that the initial contractual commitment was significantly less than that. On 19 February 2015, Orbital ATK said that its revamped Antares rocket featuring a new main engine would make its first launch in March 2016. On 29 May 2015, Orbital stated that the new engines had successfully conducted seven certification firings and all went as expected. It also stated that the first two flight models were doing its final tests and would be delivered to Orbital in early July. [10] [11] [12] [13] [14] [15]

The two RD-181s have 440 kilonewtons (100,000 lbf) more thrust than the paired AJ-26 engines used on the first-generation Antares. Northrop Grumman Innovation Systems (formerly Orbital) modified the core stage to accommodate the increased performance, and then to finish up its CRS-1 cargo contract commitment to NASA for delivering a total of 20,000 kg (44,000 lb) of cargo in only four additional flights, rather than the five more that would have been required with the AJ-26/Antares I combination.

For the Antares 230+ upgrades, debuted with the CRS-2 Cygnus NG-12 mission, heat exchangers were removed from the RD-181 engine. [16] [17]


In April 2013, it was announced that a further derivation, the RD-193, had completed testing. This version is lighter and shorter, designed for use on the light-launcher Soyuz-2.1v when the inventory of surplus NK-33 engines is exhausted. [18]

See also

Related Research Articles

Energia Soviet launch vehicle

Energia was a super-heavy lift launch vehicle. It was designed by NPO Energia of the Soviet Union for a variety of payloads including the Buran spacecraft. Control system main developer enterprise was the Khartron NPO "Electropribor". The Energia used four strap-on boosters each powered by a four-chamber RD-170 engine burning kerosene/LOX, and a central core stage with four single-chamber RD-0120 (11D122) engines fueled by liquid hydrogen/LOX.

Angara (rocket family) Russian family of RP-1/LOX fueled space-launch vehicles

The Angara rocket family is a family of space-launch vehicles being developed by the Moscow-based Khrunichev State Research and Production Space Center. The rockets are to put between 3,800 and 24,500 kg into low Earth orbit and are intended, along with Soyuz-2 variants, to replace several existing launch vehicles.

Staged combustion cycle Rocket engine operation method

The staged combustion cycle is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is thus combusted in stages. The main advantage relative to other rocket engine power cycles is high fuel efficiency, measured through specific impulse, while its main disadvantage is engineering complexity.

RD-180 Russian rocket engine

The RD-180 is a rocket engine designed and built in Russia. It features a dual combustion chamber, dual-nozzle design and is fueled by a RP-1/LOX mixture. Currently, RD-180 engines are used for the first stage of the American Atlas V launch vehicle.

RD-170 Soviet (now Russian) rocket engine, the most powerful in the world

The RD-170 is the world's most powerful liquid-fuel rocket engine and - regardless of the fuel type - second after Space Shuttle's SRB. It was designed and produced in the Soviet Union by NPO Energomash for use with the Energia launch vehicle. The engine burns the Russian equivalent of RP-1 fuel and LOX oxidizer in four combustion chambers, all supplied by one single-shaft, single-turbine turbopump rated at 170 MW (230,000 hp) in a staged combustion cycle.

NK-33 Soviet rocket engine

The NK-33 and NK-43 are rocket engines designed and built in the late 1960s and early 1970s by the Kuznetsov Design Bureau. The NK designation is derived from the initials of chief designer Nikolay Kuznetsov. The NK-33 was among the most powerful LOX/RP-1 rocket engines when it was built, with a high specific impulse and low structural mass. They were intended for the ill-fated Soviet N-1 moon rocket. The NK-33A rocket engine is now used on the first stage of the Soyuz-2-1v launch vehicle.

NPO Energomash Russian rocket engine manufacturer

NPO Energomash “V. P. Glushko” is a major Russian rocket engine manufacturer. The company primarily develops and produces liquid propellant rocket engines. Energomash originates from the Soviet design bureau OKB-456, which was founded in 1946. NPO Energomash acquired its current name on May 15, 1991, in honor of its former chief designer Valentin Glushko.

RD-107 Russian rocket engine

The RD-107 and its sibling, the RD-108, are a type of rocket engine initially used to launch R-7 Semyorka missiles. RD-107 engines were later used on space launch vehicles based on the R-7. As of 2015, very similar RD-107A and RD-108A engines are used to launch the Soyuz-FG, Soyuz-2.1a, and Soyuz-2.1b, which are in active service.

Antares (rocket) Launch vehicle produced by Orbital Sciences Corporation from the United States

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Cygnus (spacecraft) Uncrewed cargo spacecraft developed by Orbital Sciences

The Cygnus spacecraft is an expendable American cargo spacecraft developed by Orbital Sciences Corporation and now manufactured and launched by Northrop Grumman Space Systems as part of NASA's Commercial Resupply Services (CRS) program. It is launched by Northrop Grumman's Antares rocket or ULA's Atlas V and is designed to transport supplies to the International Space Station (ISS) following the retirement of the American Space Shuttle. Since August 2000, ISS resupply missions have been regularly flown by the Russian Progress spacecraft, as well as by the European Automated Transfer Vehicle, and the Japanese H-II Transfer Vehicle. With the Cygnus spacecraft and the SpaceX Dragon, NASA seeks to increase its partnerships with domestic commercial aviation and aeronautics industry.


The RD-0124 is a rocket engine burning liquid oxygen and kerosene in a staged combustion cycle. RD-0124 engines are used on the Soyuz-2.1b and Soyuz-2-1v. A slight variation of the engine, the RD-0124A, is used on the Angara rocket family URM-2 upper stage. RD-0124 is developed by Chemical Automatics Design Bureau in Voronezh.

Orel (spacecraft) Planned reusable crewed spacecraft

Orel or Oryol, formerly Federation, and PPTS, is a project by Roscosmos to develop a new-generation, partially reusable crewed spacecraft.


The RD-253 ( Russian: Раке́тный дви́гатель 253, Rocket Engine 253) and its later variants, the RD-275and 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.

The RD-120 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. Radovsky leading the development. It is manufactured by, among others, Yuzhmash in Ukraine.

This page is an incomplete list of orbital rocket engine data.

Cygnus Orb-3 Failed International Space Station (ISS) resupply mission

Orbital-3, also known as Orb-3, was an attempted flight of Cygnus, an automated cargo spacecraft developed by United States-based company Orbital Sciences, on 28 October 2014. The mission was intended to launch at 22:22:38 UTC that evening. This flight, which would have been its fourth to the International Space Station and the fifth of an Antares launch vehicle, resulted in the Antares rocket exploding seconds after liftoff.

The RD-263 (GRAU Index 15D117) is a liquid rocket engine, burning N2O4 and UDMH in the oxidizer rich staged combustion cycle. Four RD-263 engines form a propulsion module RD-264 (GRAU Index 15D119). For the R-36M KB Yuzhnoye only ordered the first stage propulsion to Energomash, instead of both stages, arguing that they were overworked with the RD-270 development. By April 1970 Yuzhnoye was getting the engine documentation. By the end of 1972 Energomash started to test fire the engines in its own test stand. And by September 1973 the engine was certified for flight. While the engine is out of production, the ICBM as well as the Dnepr remain operational as of 2015.


The RD-119 was a liquid rocket engine, burning liquid oxygen and UDMH in the gas-generator cycle. It has a huge expansion ratio on the nozzle and uses a unique propellant combination to achieve an extremely high isp of 352 s for a semi-cryogenic gas-generator engine. It also has a unique steering mechanism. The engine main nozzle is fixed, and the output of the gas generator is fed into four nozzles on the side of the engine. Instead of using gimbaled verniers to supply vector control, the combustion gases are distributed by an electrically driven system that can control the thrust among the nozzles.


The RD-214 (GRAU Index 8D59) was a liquid rocket engine, burning AK-27I (a mixture of 73% nitric acid and 27% N2O4 + iodine passivant and TM-185 (a kerosene and gasoline mix) in the gas generator cycle. As was the case with many V-2 influenced engines, the single turbine was driven by steam generated by catalytic decomposition of H2O2. It also had four combustion chambers and vector control was achieved by refractory vanes protruding into the nozzle's exhaust.

SpaceX Raptor Family of cryogenic methane-fueled rocket engines developed by SpaceX

Raptor is a family of full-flow staged combustion cycle rocket engines developed and manufactured by SpaceX, for use on the in-development Starship fully reusable launch vehicle. The engine is powered by cryogenic liquid methane and liquid oxygen (LOX), rather than the RP-1 kerosene and LOX used in SpaceX's prior Merlin and Kestrel rocket engines. The Raptor engine has more than twice the thrust of SpaceX's Merlin engine that powers their current Falcon 9 and Falcon Heavy launch vehicles.


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