Complex N1-L3

Propulsion

Stage A was used as stage I of launch vehicle N1. Stage I maximum diameter was 16.8 m (across stabilizers - 22.3 m), height - 30.1 m.

Stage B was used as stage II of launch vehicle N1. Stage II maximum diameter was about 10.3 m, height - 20.5 m.

Stage V was used as stage III of launch vehicle N1. Stage III maximum diameter was 7.6 m, height across mating interfaces - 11.5 m. .

The rocket was a package design with suspended, single-unit, spherical fuel tanks and multi-engine propulsion units on stages I, II, and III. Relying on the analysis, it was decided to employ engines sized to 150 tf. Reasons for selecting such engines were:

• such engines could be made and tested on the existing production and test experimental facilities; to develop an engine sized to 600-900 tf would require new production and experimental facilities that would sufficiently increase the rocket development terms and cost;
• an engine of 150 tf was well "adapted" to stage II of LV. This capability was implemented and similar engines having a wider nozzle section were installed on stage II that allowed to use a smaller number of engines;
• as far as reliability and functionality of engines rely on a number of bench tests (a total operating time), with equal economic costs, higher reliability could be achieved through maturing lower thrust engines;
• with a multi-engine propulsion unit a redundancy is possible (to replace a failed engine) that would sufficiently increase the program implementation probability.

For this, stages I, II, and III of LV were provided with the Kord engine control system to shut down the engine at its derating. The LV thrust was sized to a level allowing to continue the mission with one engine shut down at the initial leg of trajectory. In the final phases of the stage I flight, more engines could be shut down without harming the mission program.
The stage I PU contained engines NK-15 (initially 24 engines, then - 30) sized to ground thrust of 150 tf each and ring-accommodated, stage II incorporated eight similar engines with a high-altitude nozzle NK-15B, stage III - four engines NK-19 with a high-altitude nozzle. All the engines were of a closed-circuit design.