This page no longer updated from 31 October 2001. Latest version can be found at The N1 Story - Part 1

N1 Predecessors
N1 Predecessors - Predecessors to the N1 - From left: YaRD nuclear powered ICBM; YaKhR nuclear launch vehicle; SuperRaket; R-9 ICBM; N-III; N-IIGR; N-I of 1962; N1-L3 of 1964

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The N1 launch vehicle, developed in the 1960's, was to be the Soviet Union's counterpart to the Saturn V. The largest of a family of launch vehicles that were to replace the ICBM-derived launchers then in use, the N series was to launch Soviet cosmonauts to the moon, to Mars and Venus, and place huge military space stations into orbit. In comparison to Saturn, the project was started late, starved of funds and priority, and dogged by political and technical struggles between the chief designers Korolev, Glushko, and Chelomei. The end result was four launch failures and cancellation of the project five years after Apollo landed on the moon. Not only did a Soviet cosmonaut never land on the moon, but the Soviet Union even denied that the huge project ever existed.

Before the N1 - 1955 to 1960

Before the N1 there was an attempt to develop launchers and ICBM's to put large payloads into orbit using nuclear thermal propulsion. The first official plan for future Soviet spaceflight was contained in a decree of 30 January 1956. This set forth the following objectives:

The first approach to the rather vague last objective was the use of nuclear power. Korolev's OKB-1 began work on nuclear launchers and missiles on 30 June 1958. Competing engine designs were in development by Glushko's OKB-456 and Bondaryuk's OKB-670. The draft project designs of both bureaux used nuclear reactors in cylindrical housings, with the reactors operating at 3000 degrees K. The propellant was heated in the reactor and exhausted through four expansion nozzles. The Glushko engine operated with ammonia, while the Bondaryuk engine used a mixture of ammonia and alcohol. With such propellants a specific impulse of 430 seconds at launch was expected. Three rockets were designed by OKB-1 utilising these engines:

YaKhR-2 exteriorYaKhR-2 exterior - YaKhR-2 Nuclear-powered Launch Vehicle

Credit: © Mark Wade. 2,029 bytes. 93 x 418 pixels.

Work on this form of nuclear propulsion was abandoned at the end of 1959 when it became apparent that conventional chemical propulsion could provide nearly equivalent performance with less development, safety, and environmental risk.

Birth of the N-I

The space race with the Americans had heated up considerably since the casual program laid out in the plan of 1956 was issued. A decree of 10 December 1959 added a number of new programs, but for Korolev this was not enough. In a letter to the Central Committee of the Communist Part in January 1960 he proposed an aggressive program for Communist conquest of space. He declared:

N1 - 1962N1 - 1962 - N-I as per draft project, 1962

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The heavy rocket would be developed in two phases:

As payloads for his rocket, to be developed in accordance of the Central Committee decree of 10 December 1959, the following would be developed for launch in the period 1963 to 1965:

N-IIGR - 1962N-IIGR - 1962 - N-IIGR Multi-Warhead FOBS, 1962

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For his part, Korolev and the other chief designers would pledge to support this overall effort by the development of draft projects and fundamental research work to validate and mature the necessary technologies. They would place before the Central Committee in the third quarter of 1960 comprehensive plans for development of the new projects. It was requested that that the Central Committee authorise the design bureaux to undertake these draft projects, an that the Ministry of Finance be directed to allow the bureaux to use reserve funds to finance the work.

Korolev also requested that a decree be issued to establish a USSR Institute of Interplanetary Studies. This would be a public body like the nuclear institute in Dubna, and would co-ordinate world-wide work on space research and technology. The decree was also to authorise publication in the USSR of an open scientific technical journal covering international exploitation of space and interplanetary research.

N-III 1962N-III 1962

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This letter was followed by a meeting with Khruschchev on the subject on 3 March 1960. Korolev believed it would be truly possible with backing from the very top to have a large rocket in the USSR in a very short span of time. Unfortunately at the meeting Korolev made a slip of the tongue he would always regret, admitting that his plan had not been agreed among all of the Chief Designers. This resulted in Khrushchev throwing the matter back for a consensus plan.

By 30 May 1960 Korolev was back with a plan that now included participation of his rivals, Chelomei and Yangel. Project codes were applied and some of the work Korolev had planned was now Chelomei's. The consolidated plan was as follows:

The Chief Designers almost immediately began jockeying to change the plan. Glushko advocated development of heavy rockets by his OKB in place of those of Korolev. He proposed using rocket engines derived from his R-9 141 tonne thrust four chamber engine. His R-10 would have a total lift-off mass of 1,500 tonnes, and be followed by an R-20 with 2,000 tonnes. He advocated nitric acid/UDMH storable propellants in the first stage and higher-performance Lox/UDHM propellants in the upper stages. Later Lox/LH2 upper stages would be introduced for even higher performance. He also requested to pursue development of a 100 tonne thrust chamber; Korolev derided the idea, believing Glushko could not accomplish it.

UR-700UR-700 - UR-700 lunar landing launch vehicle - cutaway showing arrangement of N2O4 oxidiser tanks (green) and UDMH fuel tanks (orange). The outer nine 4.1 m diameter modules contained fuel and oxidizer tanks for stage 1 and fuel tanks for the three core modules. After propellant depletion, the nine outer modules would separate, leaving the three core modules to continue their burn. The third stage, based on the Proton first stage, placed the LK-700 spacecraft into a 200 km earth orbit. The LK-700 was equipped with four nearly identical clustered stages. The three outer stages fired to place the spacecraft on a translunar trajectory. The inner core stage was used for midcourse corrections, braked the spacecraft into lunar orbit, and then again until it was just above the lunar surface.

Credit: © Mark Wade. 11,990 bytes. 114 x 459 pixels.

However the May plan was approved as outlined. Therefore N-I design officially began as a result of the final government decree 715-296 of 23 June 1960 'On the Production of Various Launch Vehicles, Satellites, Spacecraft for the Military Space Forces in 1960-1967'

Design of the N-I

The same day that the decree was issued Korolev wrote to the Ministry of Defence, again trying to obtain support for a military orbital station (OS), on which a decision had been deferred to the end of the year. He pointed out that his design bureau had already completed a draft project, in which 14 work brigades had participated. Missions the station could accomplish included:

By September 1960 Korolev's engineers had already settled on the N1 configuration they would defend formally in the review of the draft project nearly two years later: a monoblock 'carcass' scheme with a total lift-off mass of 2,000 tonnes and a payload of 70 to 75 tonnes. Propellants considered included Lox/Kerosene, Lox/UDMH and Nitric Acid/UDMH. Polyblock variants were considered, but the resulting 30 propellant tanks were too complicated. The selected design would be monoblock, with spherical tanks, 10 to 11 m in diameter. At this point they were still investigating use of 170 tonne, 300 tonne, and 600 tonne thrust engines. The N-I was expected to have a payload of 3 to 4 % of its takeoff mass, and the nuclear N-II 6 to 8%.

R-56 test modelR-56 test model - R-56 dynamic test model

Credit: © Mark Wade. 12,695 bytes. 119 x 477 pixels.

By this time Glushko had new data from the US on the use of N2O4 (nitrogen tetroxide) as an oxidiser. He told Korolev that he advised replacing both Lox/UDMH and Nitric Acid/UDMH with N2O4/UDMH in the three stages of the N1. N2O4 would improve the specific impulse by 13 seconds at sea level and 14-15 seconds at altitude in comparison with the previously considered propellant combinations. To utilise it an existing turbine design would have to be increased from 25,000 to 30,000 HP, powered by a closed cycle gas generator cycle, and an increase in chamber pressure from 260 atmospheres to 300. N2O4 was more stable than nitric acid, and cost 50 to 55 roubles per tonne. For fourth stage applications, Glushko recommended use of a 10 tonne engine burning hydrogen peroxide and pentaborane. Although extremely difficult to handle and toxic, the propellants would increase the specific impulse by 54 seconds compared to nitric acid/UDMH, 40 seconds compared toN2O4/UDMH, and 25 seconds compared to Lox/Kerosene. Korolev was not at all receptive to use of any of these propellants, still preferring Lox/Kerosene.

N1-L3 TowerN1-L3 Tower - Detail of tower of N1-L3 7L

Credit: RKK Energia. 22,436 bytes. 303 x 239 pixels.

By March 1961 four design bureaux were working on development of rocket engines for the N-I and N-II. Glushko and Kuznetsov were competitively developing engines (RD-250 and NK-15) for the N-I. Isayev and Lyulka were working on advanced Lox/LH2 engines for later N-I upper stage applications. Glushko and Bondaryuk were designing new nuclear engines using LH2 propellant for the N-II.

Glushko really saw the adoption of the N2O4/UDMH propellant combination as the answer to problems he had experienced with combustion instability and chamber cooling in the four-chamber RD-111 engine developed for Korolev's GR-1 ICBM. As was the case with the R-7, Glushko was unable to solve the problems and finally resorted to four smaller chambers operating from a single turbopump. This scheme provided problems of its own, however - difficulties in synchronising the thrust of the four chambers. By using N2O4/UDMH, a combustion chamber 280 to 580 degrees less than that of Lox/Kerosene would be obtained, greatly lessening these problems and allowing faster development.

N1 Pad ConstructionN1 Pad Construction - N1 Pads Under Construction

Credit: RKK Energia. 21,705 bytes. 211 x 282 pixels.

Korolev had nothing but contempt for Glushko by this point, going back to his belief that it was Glushko's denunciation of him in 1937 that landed him in the Gulag, in the death-mines of Kolyma. Glushko had failed to solve combustion problems with the RD-105 engine, forcing the use of a four-chamber design in the RD-107 and RD-108 - chambers little larger than those on the V-2. Glushko had refused to solve the vernier rocket design for the R-7, forcing Korolev to do it. Glushko had been unable to expediently provide an upper stage engine for the R-7, forcing Korolev's own bureau to develop the S1.5400. Again with the R-9 engines, Glushko could not solve the problem of producing stable combustion in a large chamber.

In developing the S1.5400 Korolev's team demonstrated the higher performance that could be achieved with a closed-cycle engine. Glushko refused to consider this for a Lox/Kerosene RD-250 - it would only increase the already unmanageable chamber pressures and temperatures. Therefore Korolev turned to Kuznetsov's design bureau. Kuznetsov's OKB had originally been founded to exploit German engineers and develop the gigantic turboprop engines of the Tu-95 Bear bomber. But with assistance from Korolev's team he promised he could learn the technology. Kuznetsov had good relations with Korolev and was conveniently located in Samara, the same town where R-7 production was underway and N-I production was planned. Kuznetsov was willing to attempt to produce the higher-efficiency closed cycle engine that Glushko believed was impossible with the Lox/Kerosene propellants.

NK15 engineNK15 engine - NK-15 / 11D51 rocket engine for first stage of N1

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By March 1962, faced with Chelomei's favour with the military, Korolev made a detailed pitch for development of the N-I in the military context. This evolutionary program had a real chance of producing a mature launch vehicle for heavy applications.

Korolev proposed first to develop the N-II and N-III, based on the upper stages of the N-I. These would initially use the NK-9 engines developed for the R-9 and GR-1 rockets.

Step 1 would be the N-II, which would fulfil the GR-2 global rocket requirement in place of Chelomei's UR-500. It would have a gross lift-off mass of 750 tonnes, and deliver a 25 tonne payload to low earth orbit. It could also deliver a 25 megaton bomb from an under-the-radar orbital trajectory with an accuracy of 2 km. The N-11GR variant was an adaptation of the basic N-11, derived from the second and third stages of the N1 heavy booster. The GR-2 was to be a kind of enormous multiple-warhead FOBS (fractional orbit bombing system). Surrounding the top of the second stage of the rocket, like bullets in an enormous revolver, were six final stages derived from the 8K713 GR-1 last stage. Each stage had a 1,500 kg 2.2 MT nuclear warhead. The stages would separate from the main vehicle, and make violent manoeuvres using independent guidance systems to put each warhead in a different low 160 km altitude orbit. At the end of a 10,000 to 12,000 km journey along their separate orbital paths, the warheads would appear on US radar screens at the last moment with minimal warning. The total spread of the warheads would be 1800 km from left to right; two such global rockets could devastate America's major cities from coast to coast in an unstoppable first strike.

N1 engineersN1 engineers - N1 engineers study drawing

Credit: RKK Energia. 16,429 bytes. 339 x 240 pixels.

Step 2 Would be to develop the first stage of the N-I, which coupled with the already-tested N-II would provide a total lift-off mass of 2,100 tonnes and put 80 tonnes into low earth orbit. Missions for the N-I would included global reconnaissance, anti-satellite, antiballistic missile, interceptor spacecraft to rendezvous with, examine, and neutralise enemy satellites; and nuclear anti-satellites.

This programme could be conducted at minimum cost and risk. The NK-9 would be flight-tested by the end of 1963 in the improved R-9M ICBM. If the military could not afford construction of a new launch site, Korolev proposed that the N-II could be assembled in the existing R-7 MIK assembly hall and launched from the two R-7 launch pads at Baikonur, LC-1 and LC-31. Using this cut-rate approach the N-II could be developed for 2 million roubles and provide real confidence that the N-I would be successful. Korolev promised that if a prompt go-ahead was received the N-I would make a first flight by the end of 1964 or the beginning of 1965.

N1 Engine firedN1 Engine fired - N1 Engine fired on test stand

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Despite this appeal, which set forth a programme which could have discovered and eliminated the problems the N-I encountered later, the military did not support it. Chelomei was given go-ahead on 24 April 1962 to develop the UR-500 rocket for the GR-2 requirement.

Korolev's next attempt to win military support for development of the N-I was his fantastic 'Orbitalniy Poyas' (OP -Orbital Belt) scheme of 20 April 1962. Anticipating Ronald Reagan's Strategic Defence Initiative by 25 years, he painted a picture of an invincible Soviet space force patrolling the heavens. Two to three large N-I launched military manned stations would control a constellation of strategic assets. Geosynchronous nuclear-powered satellites would provide secure communications. Piloted reconnaissance spacecraft would surprise the enemy, observing military preparations without warning. The orbital stations would provide continuous observations of the territory of the imperialist block. They would control combat sputniks, manoeuvrable anti-satellites that would control the heavens from altitudes of 300 to 2,000 km. Using docking methods, the stations would be remanned, providing fresh crews to control anti-ballistic missile interceptors in 150 to 100 km orbits and to deploy separately targetable warheads at a variety of altitudes.

N1 Upper StageN1 Upper Stage - N1 Upper Stage firing on test stand

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There is not evidence the military was any more impressed with this justification than those previously put forth.

In parallel with the formal N1 draft project, since 1961, the Yangel and Chelomei bureaux had been developing alternate designs (Yangel's was designated R-56 and Chelomei's was the UR-700). Both used clustered 4 m diameter rocket stages. Both advocated each stage be equipped with a single large Glushko engine using toxic storable propellants and with a thrust of 450 to 550 tonnes. Such stages could be built in factories in Moscow or Dniepropetrovsk and shipped on the existing Soviet rail system to Baikonur. There they would be joined together but no actual metal fabrication work would have to be carried out. This approach was used with success for the smaller R-7 and Proton launch vehicles. Dynamic testing of scale models by TsNIIMASH indicated the clustering of large numbers of stages was feasible.

N1 6L LiftoffN1 6L Liftoff

Credit: RKK Energia. 15,447 bytes. 310 x 240 pixels.

N-I Draft Project - 1962

The N-I draft project was completed on 16 May 1962. The design was defended before the other Chief Designers on 2 to 16 July 1962. And this is what the draft project said:

The three stage N-I was designed to support the following objectives:

In building the rocket to attain these objectives the following additional national objectives would be met:

After extensive study it was determined that the design objective of a single launch payload of 75 tonnes into a 300 km orbit best met the required payload masses for a variety of missions:

Many trade studies were conducted comparing differing propellants and design layouts before settling on the configuration set forth in the draft project as the optimum design. These trade studies would be vital in defending the design before the expert commission against the attacks of Glushko. Propellant variants studied were:

N1 7L LiftoffN1 7L Liftoff

Credit: RKK Energia. 13,588 bytes. 308 x 239 pixels.

Conclusions were that the highest specific impulse was obtained from the Lox/Kerosene combination; and that highest tank mass was required for the N2O4, OKA-50, or AK-27 oxidisers. Use of N2O4/UDMH would result in a reduction in specific impulse of 17 to 21 seconds compared to Lox/Kerosene and a reduction in payload of 20 to 25%. Use of AK-27/UDMH would result in a 33 to 38% second reduction in specific impulse and a redaction in payload of 43 to 47%. Moreover the storable propellants would cost almost ten times more than lox/kerosene (2 million roubles per N1 launch versus 250,000 roubles). These considerations, plus the easier handling of Lox/Kerosene, confirmed the propellant selection. Lox/LH2 engines would not be available during the time scale of the initial project, but would be considered later for uprated versions of the launch vehicle.

N1 MIK Assembly HallN1 MIK Assembly Hall

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Configuration variations considered were:

N1 Model TestN1 Model Test

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All of the designs used 'hot start' stage ignition, requiring use of the familiar Warren truss open strut interstages.

Following analysis of the designs, the following were the results of the detailed design analysis:

Payload - kg70,00065,00072,00075,000
Complexity16 tanks
8 engine systems
78 armatures
30 tanks
15 engine systems
621 armatures
30 tanks
3 engine systems
331 armatures
6 tanks
3 engine systems
305 armatures
Train Cars Required26213343

N1 Wind Tunnel TestN1 Wind Tunnel Test

Credit: RKK Energia. 9,093 bytes. 320 x 240 pixels.

The disadvantages of Variants I, II, and III were the large number of servicing ports, fuelling ports, and check inspection points. It was felt that the lower complexity and higher performance of the monoblock Variant IV outweighed the much greater number of train-car loads of parts necessary. The gores of the spherical propellant tanks and panels of the side walls would be built in the factory in Samara and only final assembly of the launch vehicle would be undertaken at the cosmodrome.

In the United States launch from coastal Cape Canaveral permitted the 10 m diameter Saturn IC and Saturn II stages to be shipped by barge from the factories to the launch site. No such possibility existed for Baikonur, in the arid steppes of Kazakhstan. Alternate launch sites were considered (and some space engineers wistfully hoped for a launch site on the balmy Black Sea) but Baikonur remained the only possibility. Due to the geography of the Soviet Union there was no other launch location with relatively uninhabited downrange areas for impact of spent rocket stages.

N1 Subscale ModelN1 Subscale Model

Credit: RKK Energia. 22,171 bytes. 338 x 240 pixels.

By this analysis the selection of lox/kerosene propellants and the monoblock configuration were justified in the draft project. Indirectly the problems of polyblock designs like those of Yangel and Chelomei were considered and attacked.

For the 75 tonne payload a gross lift-off mass of 2,000 to 2,300 tonnes would be required using only Lox/Kerosene propellants in all stages. It would be necessary to build a 150 tonne thrust closed-cycle rocket engine for use in the launch vehicle (at that time the largest rocket engine chamber built in Russia was 40 tonnes, open cycle). 24 NK-15/11D51 engines would be used in the first stage, 8 NK-15V/11D52 engines in the second stage, and 4 smaller NK-19/11D53 engines in the third stage. Development of engines in the 600 to 900 tonne thrust were studied but would have required development of new technologies and not been available during the project's time scale. A 150 tonne engine was well sized for use in the second stage and the clustering of large numbers of them in the first stage could be managed through use of the KORD control system (an elaborate automatic system that would monitor engine health, shut down any failing engine and its opposite number, allowing continued operation of the cluster until the required stage performance was reached).

N1-L3 - 1964N1-L3 - 1964 - N1-L3 as per advanced project, 1964

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From the N1 stages two smaller launch vehicles would be derived. The N11 would use versions of the second and third stages of the N1, together with the third stage of the GR-1. This would have a lift-off mass of 700 tonnes and a 20 tonne payload into low earth orbit. It was designed for the same missions as the Chelomei UR-500 Proton booster. The N111 would use derivatives of the third stages of the N1 and the second stage of Korolev's R-9 ICBM. This would result in a lift-off mass of 200 tonnes and a five tonne payload, allowing it to replace the R-7 derived Vostok and Soyuz boosters.

N-I Goes into Production

Despite intense criticism by Glushko, Keldysh and the rest of the expert commission supported the draft project. But the programme was still without an authorised mission. Following the approval of the draft project there was a more informal discussion between Khrushchev and the Chief Designers at the Soviet leader's estate at Pitsunda, on the Black Sea, in August. Korolev went over the heads of the military once again and pitched his giant military space station as a rationale for the project. At the conclusion of the meeting, Khrushchev ordered start of the project to put a 75 tonne manned platform with nuclear weapons into low earth orbit. The official decree authorising N-I production was issued on 24 September 1962 with first flight to occur in 1965. This set forth the first of a series of optimistic schedules for development of the launch vehicle. Completion of third stage tests was expected by the end of 1964, first and second stages by mid-1965, completion of all engine test stand runs by the first quarter of 1965, completion of the launch complex by the end of 1964, and first launch in 1965.

Model of N1 padModel of N1 pad

Credit: RKK Energia. 24,069 bytes. 340 x 240 pixels.

So after two years of struggle, Korolev finally had his authorisation in hand. But it turned out not to be enough. He had authorisation for the rocket, but no support from the military ranks for a payload for it to launch.

Barmin's GSKB SpetsMash was given responsibility for design and construction of the launch facilities. In March 1963 design work started on the N1 launch complex. The ground-breaking ceremony was held a year later and construction began of the N1 launch complex and assembly buildings

Continued in The N1 Story - Part 2

N1 RolloutN1 Rollout - N1 Rollout - base of booster

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N1 RolloutN1 Rollout - N1 Rollout - view from inside MIK

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N1 CutawayN1 Cutaway - Dimensioned Russian cutaway drawing of N1 launch vehicle.

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Last update 12 March 2001.
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© Mark Wade, 2001 .