Encyclopedia Astronautica

Block D / 11D68
Aft view of the Block D lunar crasher stage and its 11D68 engine. The Block D would have taken the LK lunar lander to near the surface of the moon. This stage remains in use today atop the Proton rocket.
Credit: © Mark Wade
Korolev Lox/Kerosene rocket engine. 71 kN. Zenit stage 3. Developed 1981-1990. Isp=361s.

Application: Zenit stage 3.

Engine: 300 kg (660 lb). Chamber Pressure: 78.00 bar. Area Ratio: 189. Thrust to Weight Ratio: 24.13.

AKA: 11D58Z.
Status: Developed 1981-1990.
Unfuelled mass: 300 kg (660 lb).
Diameter: 2.90 m (9.50 ft).
Thrust: 71.00 kN (15,961 lbf).
Specific impulse: 361 s.
Burn time: 660 s.

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Associated Countries
See also
Associated Launch Vehicles
  • Zenit Zenit was to be a modular new generation medium Soviet launch vehicle, replacing the various ICBM-derived launch vehicles in use since the 1960's (Tsiklon and Soyuz). A version of the first stage was used as strap-ons for the cancelled Energia heavy booster. But it was built by Yuzhnoye in the Ukraine; when the Soviet Union broke up planned large-scale production for the Soviet military was abandoned (Angara development was begun as an indigenous alternative). Launch pads were completed only at Baikonur; those at Plesetsk were never finished and are planned to be completed as Angara pads. However the vehicle found new life as a commercial launch vehicle, launched from a sea platform by an American/Ukrainian consortium. More...

Associated Manufacturers and Agencies
  • Korolev Russian manufacturer of rockets, spacecraft, and rocket engines. Korolev Design Bureau, Kaliningrad, Russia. More...

Associated Propellants
  • Lox/Kerosene Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. In January 1953 Rocketdyne commenced the REAP program to develop a number of improvements to the engines being developed for the Navaho and Atlas missiles. Among these was development of a special grade of kerosene suitable for rocket engines. Prior to that any number of rocket propellants derived from petroleum had been used. Goddard had begun with gasoline, and there were experimental engines powered by kerosene, diesel oil, paint thinner, or jet fuel kerosene JP-4 or JP-5. The wide variance in physical properties among fuels of the same class led to the identification of narrow-range petroleum fractions, embodied in 1954 in the standard US kerosene rocket fuel RP-1, covered by Military Specification MIL-R-25576. In Russia, similar specifications were developed for kerosene under the specifications T-1 and RG-1. The Russians also developed a compound of unknown formulation in the 1980's known as 'Sintin', or synthetic kerosene. More...

Associated Stages
  • Zenit-3 Lox/Kerosene propellant rocket stage. Loaded/empty mass 17,300/2,720 kg. Thrust 84.92 kN. Vacuum specific impulse 352 seconds. Adaptation of Block D for Zenit. More...

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