Engine Model: S5.51. Government Designation: 11D68. Other Designations: S5.51. Designer: Isayev. Developed in: 1964-72. Application: Soyuz LOK lunar orbiter. Propellants: N2O4/UDMH. Thrust(vac): 33.196 kN (7,463 lbf). Throttled thrust(vac): 4.089 kN (919 lbf). Isp: 314 sec. Burn time: 700 sec. Mass Engine: 480 kg (1,050 lb). Length: 2.77 m (9.08 ft). Chambers: 2 + 1. Oxidizer to Fuel Ratio: 1.85. Thrust to Weight Ratio: 7.05. Country: Russia. Status: Hardware. First Flight: 1969. Complex engine used to maneuver the LOK to a rendezvous with the LK lander in lunar orbit, then propel the LOK out of lunar orbit (large engine), and for midcourse corrections (small engine). Burn time 700 + 300 sec. Oxidizer to fuel ratio 1,85 / 1,76.
S5.51 used on Spacecraft
Bibliography:- Semenov, Yu. P., S P Korolev Space Corporation Energia, RKK Energia, 1994.
- Haeseler, Dietrich, Visit to the museum of Chemical Machining Design Bureau, Kalinin 1994 via Dietrich Haeseler.
