Third stage of the N1 rocket (original) (raw)

Third stage of the N1 rocket

Block V (named after the third letter in the Russian alphabet) served as the third stage of the N1 launch vehicle, completing the booster section of the rocket required to reach an initial orbit around the Earth with the L3 lunar expeditionary complex or any other potential payload.

Previous chapter: Block B (Stage II) of the N1 rocket

Known specifications of Block V (Stage III) of the N1 rocket:

The third stage of the N1 rocket sat on the top of the truss adapter of the Block B second stage and structurally largely represented a scaled down version of the second stage.

From bottom to top, Block V consisted of an aft section, a four-engine cluster with four NK-19 engines, a structural ring, an oxidizer tank, a conical inter-tank adapter, a fuel tank and a conical adapter interfacing with the fourth stage (Block G). The aft section consisted of three segments, which were designed to split and fall off the third stage immediately after the separation of the second stage.

In the original design, the mass of the fueled Block V was 150 tons, however after the project had been reconsidered in 1962 to increase payload, the third stage had to accommodate more propellant and its mass grew up to 185 tons. Extra fuel added 70 seconds to the engine burn, bringing the total operation time for Block V during orbital ascent to 370 seconds. The combined thrust of the propulsion system in vacuum increased from 160.8 tons to 163 tons.

The larger oxidizer tank, with a diameter of 6.06 meters and a volume of 98.6 cubic meters, rested on the main structural ring through 48 thermally insulated attachments to reduce the boiling of the cryogenically cooled liquid oxygen inside. At the bottom of the tank, there were four intakes for oxidizer supply lines, each leading to four NK-19 (11D53) engines. The stage was reported to have a propellant consumption rate of 0.581 tons per second. (120)

The conical intertank compartment sat on top of the structural ring and held a smaller kerosene tank with a diameter of 4.88 meters and a volume of 61.6 cubic meters with the help of 24 attachments. On its exterior, the inter-tank structure had four bypass lines routing propellant around the oxidizer tank into the engines.

In addition to electric conduits, various connections between Block V and Block B below were provided via five pneumatic and hydraulic interfaces, including two pneumatic connector pads, two quick disconnect pads and one cut-off interface.

The pneumatic pad No. 3817-0 comprised of 13 lines for the following functions:

• The purging of fuel lines in the propulsion system of Block V;
• The control of air conditioning of the thermal flow sensor in Block V;
• The supply of gas for aeration;
• The supply of gas for the valve of the air circulation in Block V;
• The purging of the fuel tank drainage line in Block V;
• The control of the DKP system in the oxidizer line of Block V;
• The gas release from onboard helium tanks in Block V;
• The post-pressurization of the oxidizer tank in Block V;
• The pre-launch pressurization for oxidizer tanks in Block V and upper stages;
• The pre-launch pressurization of the fuel tank in Block V;
• The DPK system control in the tanks of upper stages;
• The supply of nitrogen.

The pneumatic pad No. 3931-0A had four lines providing the following functions:

• The control of drainage valves in fuel tanks in Block V and Block G;
• The drainage of of fuel tank in Block V;
• The control of drainage valves in oxidizer tanks in Block V and Block G;
• The control of the RKO system in Block V during opening for the preliminary and main trust stage;

The disconnect interface No. 3844-0 had one line which provides gas drainage for turbo-generator in Block V.

The disconnect interface No. 3824-0 had one line which delivers gas to turbo-generator in Block V.

The cut-off panel had one line that provides airation of oxidizer pump cavities in the engines of Block V.

Evolution of the stage

Booster stage of the N1 rocket being prepared for integration with the L3 complex on the transporter-erector system.

By 1970, OKB-276 had developed the NK-39 (11D113) engine variant to replace NK-19 on Block V. NK-39 was first installed on Vehicle No. 6L, which was launched in June 1971 and on Vehicle No. 7L, that flew in November 1972. Finally, NK-39 was also aboard Vehicle No. 8L (INSIDER CONTENT), whose launch was scheduled as early as August 1974, but it was cancelled with the end of the N1-L3 project in May 1974.

The third stage of the N1 rocket was expected to double as the second stage of the N11 rocket and as the first stage of the N111 rocket, but neither of them were ever built.

Next chapter: The fourth stage (Block G) of the N1 rocket

Page author: Anatoly Zak; last update:November 6, 2025

Page editor: Alain Chabot; last edit: March 26, 2025

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