|Manufacturer||Khrunichev State Research and Production Space Center|
|Country of origin||Russia|
|Used on||Angara A5 (upper stage)|
|Height||10.4 meters (34 ft)|
|Diameter||3.8 meters (12 ft)|
|Gross mass||23,530 kilograms (51,870 lb)|
|Propellant mass||19,600 kilograms (43,200 lb)|
|Thrust||68.6 kilonewtons (15,400 lbf)|
|Specific impulse||463 seconds (4.54 km/s)|
|Burn time||1,350 s|
The KVTK (Russian: Кислородно-водородный тяжёлого класса, Oxygen/Hydrogen Heavy Class) is a liquid oxygen/hydrogen upper stage for high energy orbits that is currently under development. The KVTK contains an RD-0146D engine and is designed for use on Angara rockets. KVTK would be the first hydrogen-powered upper stage for use on a Russian launch vehicle, although Khrunichev has previously produced a hydrogen-powered upper stage (KVD-1) for the Indian GSLV. KVTK is designed to provide up to five ignitions, allowing for complex orbital maneuvering, and have an on-orbit lifespan of up to nine hours. KVTK would allow an increase in payload to GTO of 20-50% compared to the Angara A5's standard Briz-M upper stage, powered by UDMH and N2O4.
The KVTK was originally studied as an upper stage for the Energia family of rockets, but in 1987 was superseded by the RCS stage (Retro and Corrections Stage), based loosely on the American S-IVB. In 1996, consideration was briefly given to constructing a KVTK-derived Russian Propulsion Module for the International Space Station. Most likely, this module would have been transported to the ISS by a Space Shuttle.
The KVSK (RCAF) would be a smaller cryogenic stage carrying 10,760 kilograms (23,720 lb) of propellant for the proposed Angara A3, while the KVSK-A7 would be a larger stage loaded with 26,500 kilograms (58,400 lb) for the proposed Angara A7.