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S5.51 LOK engine
S5.51 LOK engine

Credit: © Mark Wade. 64,079 bytes. 555 x 390 pixels.

Government Designation: 11D68. Other Designations: S5.51. Designer: Isayev. Developed in: 1964-72. Application: Soyuz LOK lunar orbiter. Used on spacecraft: Soyuz 7K-LOK. Propellants: N2O4/UDMH Thrust(vac): 3,388 kgf. Thrust(vac): 33.20 kN. Isp: 314 sec. Burn time: 700 sec. Mass Engine: 480 kg. Length: 2.8 m. Chambers: 2 + 1. Oxidizer to Fuel Ratio: 1.85. Country: Russia. Status: Hardware. First Flight: 1969. References: 89 , 314 . Comments: 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 LOK engineS5.51 LOK engine - Side view of the Isayev S5.51 engine used in the Soyuz 7K-LOK lunar orbiter.

Credit: © Mark Wade. 60,916 bytes. 385 x 511 pixels.

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