Blok E[1]
ManufacturerYuzhnoye Design Bureau
Country of originSoviet Union
Used onLK
General characteristics
Gross mass2,950 kg (6,500 lb)
Launch history
Launch date
Blok E
Powered by11D410
Maximum thrust20 kN (4,500 lbf)
Specific impulse315 s (3.09 km/s)

Blok E (or Block E) is the propulsion unit of Soviet lunar module LK, developed in 1960s by Yuzhnoye Design Bureau as a part of the manned lunar landing program.[1]

Blok E was designed to soft land the LK on the surface of the Moon after orbital velocity was cancelled by Blok D. Later the same stage would fire for the second time for the liftoff and ascent from the Moon to rendezvous with the orbiting Soyuz 7K-LOK.[3][4] Blok E used RD-858 (or 11D411),[5] which has one nozzle and is deeply throttleable (from 2050 kg to 858 kg of thrust),[6] as the primary engine. The backup engine was RD-859 (or 11D412),[5] which has two nozzles.

Together, the two engines formed the propulsion system designated 11D410.[7] Both engines burned a mix of unsymmetrical dimethyl hydrazine and nitrogen tetroxide. The hypergolic propellant components guaranteed their easy storage during a lunar expedition lasting at least 11 or 12 days.

The engines were equipped with clam-shell doors to prevent damaging it while staying on the surface of the Moon. There were four additional vernier engines placed between main and backup engine nozzles.

See also


  1. ^ a b "The many lives of the Soviet lunar landing engine".
  2. ^ "LK".
  3. ^ "LK spacecraft and Block E". Archived from the original on 2013-12-30. Retrieved 2013-12-15.
  4. ^ "Liquid propellant propulsion systems, Yuzhnoe Design Bureau". Archived from the original on 2014-07-14. Retrieved 2014-07-10.
  5. ^ a b "LK (L3, T2K)".
  6. ^ "RD-858". Archived from the original on 2016-03-26. Retrieved 2016-03-18.
  7. ^