|Country of origin||Russia|
|Propellant||LOX / RP-1|
|Thrust (vac.)||2.090 MN (470,000 lbf)|
|Thrust (SL)||1.920 MN (432,000 lbf)|
|Chamber pressure||3,746 psi (25,830 kPa)(258 bar) or 263.4 kg/cm²|
|Isp (vac.)||337 s|
|Isp (SL)||310.7 s|
|Burn time||150 s |
|Length||4,000 mm (160 in)|
|Diameter||1,450 mm (57 in)|
|Dry weight||2,200 kg (4,900 lb)|
Burn ignition is provided by a chemical method, by feeding into the combustion chamber special starting fuel 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 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 September 5, 2008, the creator of the engine, NPO Energomash, reported that the engine has completed the full cycle of development and burn tests and is ready for manufacturing and delivery. The primary launch vehicle utilizing this engine is the Angara rocket, currently being developed.
A version of the RD-191 with thrust reduced to 170 tonnes, called RD-151, was fire-tested on July 30, 2009. The first flight test of this engine was conducted on August 25, 2009 as part of the first launch of South Korean Naro-1 rocket.
As of 2010, the engine has passed all development phases and its nine prototypes have 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. Currently, 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-5A heavy launcher. Despite problems with funding, work on the RD-191 engine is in line with the Angara rocket family's master schedule.
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.
- http://www.astronautix.com/engines/rd191.htm RD-191 Rocket Engine
- "A new engine is ready for Angara (in Russian)". 2008-09-05.
- "Successful Tests of Angara Stage 1 Engine". Khrunichev. 2007-12-12.
- "First launch of KSLV-1 is conducted". 2009-08-25.
- "S. Korea to launch first space rocket on Aug. 19". 2009-08-25.
- Chvanov, Vladimir (2010). "Russia's liquid rocket enginges are unrivalled". Military Parade (2): 40–41.
- "New engine for light rocket "Soyuz" prepare for mass production at the end of the year" (in Russian). Новости космонавтики. Retrieved 8 April 2013.
- "RD-191". Energomash.