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astronautix.com The N1 Story - Part 2

N1 Late Versions
N1 Late Versions
Late versions of N1: from left: N1F; N1M; N1F with Block S, R upper stages; N1F with Block Sr upper stage; Airbreathing N1 for MOK support; Kistler

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Nuclear N-I's - 1961 to 1963

Following abandonment of the nuclear-ammonia ICBM projects, the engine bureaux of Bondaryuk (OKB-670) and Glushko (OKB-456) continued study of nuclear propulsion, but using liquid hydrogen for upper stage applications. Engines of 200 tonnes and 40 tonnes thrust with a specific impulse of 900 to 950 seconds were being considered. At the end of 1961 both bureaux completed their draft projects and it was decided to continue work on development of an engine in the 30 to 40 tonne thrust range. In the following year Korolev was asked to study application of such engines, followed by a demand in May 1963 from the Scientific-Technical Soviet for specific recommendations.

Korolev considered three variants based on the N1:

Considered for each case were nuclear engine designs Type A (18 tonnes thrust, 4.8 tonnes mass), AF (20 tonnes thrust, 3.25 tonnes mass), V (40 tonnes thrust, 18 tonnes mass), and V with a bioshield for use on manned flights (40 tonnes thrust, 25 tonnes mass).


Early model of N1Early model of N1 - Early model of N1 being erected by the Grasshopper carrier. A retouched version of this photo was the first one released to the West.

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The study concluded that the two stage vehicle was the most promising. Compared to an equivalent vehicle using liquid oxygen/liquid hydrogen, mass in low earth orbit would be more than doubled. Optimal stage size was 700 to 800 tonnes for the Type A engines and 1,500 to 2,000 tonnes for the type V engines (this resulted in a halaciously large number of nuclear engines by Western standards). Use of the nuclear stage would result in a single N1 launch being able to launch a round-trip lunar landing (mass landed on lunar surface over 24 tonnes with return of a 5 tonne capsule to earth).

For a Mars expedition, it was calculated that the AF engine would deliver 40% more payload than a chemical stage, and the V would deliver 50% more. But Korolev's study also effectively killed the program by noting that his favoured solution, a nuclear electric ion engine, would deliver 70% more payload than the Lox/LH2 stage.

Further investigation of nuclear thermal stages for the N1 does not seem to have been pursued. Bondaryuk and Glushko turned to Chelomei and his competing UR-700 rocket for future application of such stages.


N1 second stageN1 second stage - N1 second stage undergoing dynamic test. This is believed to be the N1M version of the stage, showing the insulation panels to protect the cryogenic propellants.

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N1 Payloads - the Moon Calls - 1963

On 23 September 1963 Korolev submitted his plans for space projects in the period 1965 to 1975. He now saw a clear chance to again appeal to the leadership for a manned lunar landing program. He dusted off his rejected L-1 circumlunar project, but added four new spacecraft that would allow reconnaissance, followed by landing on the moon and extended exploration of its surface.

The first two projects, as before, would use R-7 based launch vehicles and extensive docking and refuelling operations in low earth orbit. But elements of these would be used in the last three, which would map the moon from lunar orbit, land men on its surface, and explore it with a manned crawler.

L-1

This revision to the original L1 project of 1962 had the same objective of sending two men on a circumlunar flyby trajectory. But now the Soyuz had a reverse configuration of that used earlier. From fore to aft, the modules were: the Descent Capsule (SA), Living Module (BO); Equipment Module (AO); Propulsion Module (AO); Rendezvous electronics module (NO) and Docking Unit (SU). This configuration would be important in the later N1-based projects. As before, the system consisted of the 7K manned spacecraft, the 9K rocket spacecraft, and the 11K tanker. A total of six launches of the 11A511 Soyuz booster would be required. The 9K rocket stage would be put in orbit first. It would be followed by four 11K tankers which would top off the tanks of the rocket block. Then, when all was ready, the 7K manned craft would be put into orbit and dock with the 9K stage. The stage would fire and put the manned spacecraft on a translunar trajectory.


N1 Early DesignN1 Early Design - Early design of N1 with aerospike first stage

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The 7K would be equipped with cinema cameras and scientific sensors to record the lunar surface during the flyby, which would be at from 1,000 to 20,000 km from the lunar surface. Total flight time was 7 to 8 days. The SA would separate from the 7K at 120 to 150 km altitude and re-enter the earth’s atmosphere at 11 km/sec. After decelerating to subsonic speed, the SA’s parachute would open at 10-18 km altitude. Total mass of the L1 in low earth orbit was 23,000 kg and the flyby mass of the Soyuz alone was 5,100 kg.

L-2

The L2 was a project to land a remote-controlled self-propelled rover on the surface of the moon. It would use the same rocket stage and tanker elements developed for the L1 manned circumlunar project. It can be seen to be the direct ancestor of the Ye-8 Lunokhod lunar rovers of the 1970’s.

The objective of the L-2 would be to conduct scientific research on the lunar surface and to allow selection of a favourable landing point for later manned flights. A television system would send back panoramic television pictures. The rover would be nuclear-powered and equipped with a radio beacon for later manned expeditions to home on for precision landings. It would also investigate:


N-IM 1965N-IM 1965 - N-IM version of 1965

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  • The relief of the lunar surface
  • The mechanical properties of the lunar soil
  • The microscopic structure of the surface
  • The magnetic fields of the moon
  • Cosmic ray flux
  • Solar insolation at the surface

    The L-2 system consisted of:

    Total mass of the L-2 + 13K + 9K complex at ignition of the 9K for translunar injection was 23,000 kg. Total mass of the L-2 and 13K in their translunar cruise configuration was 5,000 kg. As was the case for the L-1, six launches of the Soyuz 11A511 booster would be required to assemble the L-2 in a 225 km low earth assembly orbit.

    L-3

    Korolev’s first version of the L-3 manned spacecraft was designed to make a direct lunar landing using the earth orbit rendezvous method. It was a 200 tonne spacecraft requiring three N1 launches and a single Soyuz 11A5ll launch to assemble in low earth orbit. The first N1 launch would place the 75 tonne partially-fuelled TLI stage and L3 spacecraft (except the L1 manned return craft) into low earth orbit. Two further N1 launches would orbit 75 tonne tankers which would rendezvous and dock with the first payload and top off its propellant tanks. Then the Soyuz would be launched for an automated rear-end docking with the entire L3 stack. The L3 spacecraft thereby assembled consisted of:


    N-IF VariantsN-IF Variants - N-IF Versions, from left: N1-L3; N-IF; N-IUV-III; N-IFV-III; N-IFV-III,II

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    The total L3 mission would take ten to seventeen days. 2.5 to 3.5 days would be spent on the translunar and transearth legs of the mission Five to ten days would be spent on the lunar surface.


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    The L3 was not authorised in this form and it would over two years before a very belated start was made to beat the Americans in the moon-landing race. The L3 reformulated for the crash program would require only a single uprated N1 launch and use the lunar-orbit-rendezvous method, with a single-man lander.

    L-4

    The L-4 Manned Lunar Orbiter Research Spacecraft would have taken two to three cosmonauts into lunar orbit for an extended survey and mapping mission. The L-4 complex, with a total mass of 75 tonnes, would be placed into orbit in a single N1 launch, and would consist of:


    N-IMV-IIIN-IMV-III

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    L-5

    The L-5 Heavy Lunar Self-Propelled Craft would be used for extended manned reconnaissance of the lunar surface. With a maximum speed of 20 km/hour, it would provide living accommodation for three cosmonauts and 3,500 kg of provisions. The crews themselves would be landed on the moon using the L-3 complex.


    N-IFV-II, IIIN-IFV-II, III - N-IFV-II, III of 1965

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    Project in Crisis and a New Mission - 1964

    At the beginning of 1964, despite hard work in the previous year, it was apparent that there were still one to two years of development and construction to go and the target dates set in the decree would not be met.

    On 24 March 1964 Korolev managed another meeting with Khrushchev, where he again advocated an aggressive plan of lunar and interplanetary exploration. He dusted off his old L3 lunar landing scheme. Two variants of the L3 would be developed: the basic version would use Lox and Kerosene in Rocket Blocks G and D, with N2O4/UDMH in Block E. A later version would use Lox/LH2 in all of these upper stages. This would add 4 tonnes to the lunar surface payload. Korolev promised to have an L3 draft proposal completed in 1964 and the spacecraft in service by 1966. Development of the Lox/LH2 engines would take place from 1964 to 1967. He even pressed development of the TMK / TMK-E interplanetary manned spacecraft, using the newest designs from his bureau with nuclear electric engines. Khrushchev expressed some interest now in the lunar landing scheme, in the face of the American's evident determination to press on with project Apollo.


    N1FV-IIIN1FV-III - N-IFV-III design of 1965

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    Feeling he had Khrushchev’s support, Korolev on 25 May 1964 drafted a letter to Brezhnev, then in charge of missile development. Korolev complained of the delays in the N-I due to lack of priority and financing. He noted that of 11 million roubles budgeted for construction of the launch complex in1964, only 7 million had been received. Two years after authorisation ,work on the guidance systems had not even begun, due to the priority of military projects. Korolev tried to put the screws to Brezhnev by noting that Khrushchev had always sponsored scientific projects, and that with the Saturn I rocket the Americans had already surpassed the Americans in the booster race. He also attempted to sabotage Chelomei's LK-1 circumlunar project yet again, by noting that he was wasting his time with Glushko's 'low energy' propellants and that a single launch of his N-II could put a Soyuz modification on the same mission.

    It is not clear if this letter was sent; and if so, it certainly hurt Korolev with Brezhnev when he would ascend to power in a year's time. But he had convinced Khrushchev of the necessity for a high priority lunar landing project to beat the Americans.


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    The Lunar Landing Mission and the N-I Upgraded

    On 3 August 1964 Command number 655-268 issued by Central Committee of Communist Party for the first time set the objective for OKB-1 to put one man on the moon and return him safely to earth - ahead of the Americans (who had begun over three years earlier, in April 1961). To achieve this aim a large part of the industry had to be mobilised (though not the competing and dissenting Glushko, Yangel and Chelomei enterprises). This would require design of what was designated the L3 complex, with the combined launch vehicle/spacecraft termed the N1-L3. The L3 would utilise the same lunar orbit rendezvous method to achieve moon landing as was selected for the Apollo program. By upgrading the N1 from a 75 tonne to a 95 tonne payload capacity it was felt possible that a single N1 launch could accomplish the mission. The L3 complex itself, with a total mass of 95 tonnes, would consist of a fourth stage (Block G) for the N1 to take the L3 from low earth orbit to trans-lunar trajectory; a lunar orbiter with a Soyuz re-entry capsule for return to earth (LOK); a lunar lander (LK) for the landing of a single cosmonaut on the surface of the moon; and a deceleration stage (Block D) which would brake the L3 complex into lunar orbit and then take the LK lander to near zero velocity above the surface of the moon.


    N1 6L liftoffN1 6L liftoff

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    The N1-L3 complex was designed not just for a quick initial moon landing, but also for exploration of the moon and near-lunar space for both scientific and military purposes.

    In what was only to be the first stage of a sustained campaign, single cosmonauts would land on the lunar surface. However this would be just part of a larger mission with the following objectives:

    The lunar expedition would utilise the lunar-orbit rendezvous method for reaching the surface. In this way the mission could be accomplished in just one launch of an improved N1. The lunar flight plan was as follows: Total mission time was to be 11 to 12 days.


    2 N1s Mounted on Pad2 N1s Mounted on Pad

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    The work for the L3 project was split as follows:


    N1 5L ExplosionN1 5L Explosion - Final explosion of N1 5L, destroying pad.

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    The plan was for the first launch of the N1 to be in the first quarter of 1966, with the first lunar landings in 1967 to 1968, ahead of the American goal of 1969.

    The original N1 with its payload of 75 tonnes to a 300 km, 65 degree inclination orbit would require two to three launches to assemble a lunar landing expedition in earth orbit. One result of the draft project was the decision to increase the N1 payload to 95 tonnes to allow the L3 to be launched toward the moon in one launch. The following measures would increase the N1 payload to 91.5 tonnes:


    N1 5L Falls BackN1 5L Falls Back - Having just cleared the towr, N1 5L falls back onto the pad at a 45 degree agnle.

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    Then the following measures would increase the payload to 95 tonnes:

    The 3 August 1964 decree foresaw completion of manufacture of the N1-L3 to the following schedule: 4 in 1966; 6 in 1967; and 6 in 1968. By September 1964 construction began of the first N1 launch pad (LC110R). Then on October 13, while Voskhod 1 was in orbit, Khrushchev was removed from power and Brezhnev's faction assumed control of Politburo. This immediately led to a shift of political forces. Chelomei lost his main patron and Korolev immediately again attempted to gain control of the L1 manned circumlunar project. Many of Chelomei's pet projects, such as the R Raketoplan, the K Kosmoplans, and their UR-200 booster, were cancelled.

    Meanwhile the advance design project for the N1-L3 was completed in collaboration with Kuznetsov's OKB-586 on 30 December 1964. The decree for production of 16 shipsets of spacecraft and boosters was issued on 26 January 1965. After several skirmishes during the year, on 25 October 1965 the Chelomei circumlunar project was given to Korolev and Chelomei's LK-1 manned capsule was cancelled. The new scenario would use a stripped version of Korolev's Soyuz atop Chelomei's UR-500 Proton launch vehicle. While a victory for Korolev, it was an added project at a time that the N1-L3 was in serious technical and schedule problems. Korolev had begun to admit to his colleagues that the moon landing could not come until 1969 at the earliest. He also noted that while development of the Soyuz was proceeding on schedule, Chelomei’s LK-1 was badly lagging behind (although the Proton booster was on schedule).


    N1 5L clears towerN1 5L clears tower - N1 5L Clears the tower but falters as the KORD system incorrectly shuts down engines.

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    On 25 August 1965 a knock-down-drag-out meeting was held between Ustinov and the Chief Designers. Although he was a received as much criticism as he gave, Korolev’s hand in engineering the meeting to wrest control of the LK-1 from Chelomei can be seen. Ustinov contracted the mounting successes of the American space projects with the continuing delays and failures of the Soviet projects. The problems were clearly gross underfunding of the entire programme and duplication of effort between the Chief Designers. The Chief Designers fought bitterly and would not back down. But it was clear finally to the leadership that some drastic reorganisation was required to keep up in the space race. Korolev could see that he would soon have the whole thing under his control at last.

    Advanced Versions of the N1 - 1965

    After completing production drawing release, Korolev's design teams could consider future improved variants of the N1. On November 9, 1965 a four volume study was issued covering these variants. These were:


    N1 subassembliesN1 subassemblies - N1 tank sections were built in Samara, then shipped to Baikonur for assembly of the launch vehicle.

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    At this critical juncture Korolev learned that he was terminally ill with cancer of the colon.

    The Death of Korolev - the Race to the Moon - Advanced Upper Stages - 1966 to 1969

    On January 14, 1966 Korolev died in Moscow during colon surgery. He had kept his illness a secret from his colleagues and his death at 56 came as a surprise to many. This is often cited as a blow from which the project never recovered. His successor, Mishin, did not have the forceful personality and political connections of the original Chief Designer. Korolev also had a legendary ability to motivate his staff and cajole co-operative design bureaux to prioritise work for OKB-1 that Mishin was never able to duplicate.

    The project continued. In February 1966 construction started of the second N1 launch pad (LC 110L). By November the first N1 hardware arrived at Baikonur and construction of the 1M1 full-size mock-up of the launch vehicle began. On 16 November 1966 another Keldysh-headed expert commission considered the state of the programme. With Korolev dead, once again Glushko, Chelomei, and Yangel advocated development of the UR-700 or R-56 in lieu of the N1. While it was agreed that engine development and studies of these launch vehicles could continue, the government decree issued approved Mishin's draft plan for the first lunar landing. The first N1 launch was now to be in March 1968 (two years late to the very optimistic schedule set when the project was first full approved).


    N1 stagesN1 stages - N1 stages in teh assembly hall

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    However now the schedule seemed to be holding and in February 1967 the government approved integrated L1/L3 project plans indicating a landing on the moon by the end of 1968 - still ahead of the Americans. The N1 test plan envisioned third quarter 1967 as the beginning of flight hardware construction. First manned L1 circumlunar mission using the Proton booster was anticipated as early as June 1967. The first N1 launch was still set for March 1968. A moon landing would not come until the third quarter of 1969 at the earliest.

    In February assembly of the first N1 began at the Progress plant in Samara. On March 10 1967 Cosmos 146 was launched in the first test of hardware (the Block D stage and L1 lunar spacecraft) to be used in the L1 and L3 projects. The boilerplate Soyuz 7K-L1 was launched by a Proton into the planned highly elliptical earth orbit. The Block D stage functioned correctly in its first test, putting the spacecraft into a translunar trajectory. The spacecraft was not aimed at the moon and no recovery was planned or attempted. This successful launch created a false confidence just before the string of failures that would follow. On April 8 Cosmos 154 reached earth orbit but the Block D translunar injection stage failed to fire (ullage rockets, which had to fire to settle propellants in tanks before main engine fired, were jettisoned prematurely). The spacecraft burned up two days later when its orbit decayed.


    N1 tank assemblyN1 tank assembly - Subassmeblies from Samara were built up into stage bulkheads on assembly jigs at Baikonur.

    Credit: RKK Energia. 16,696 bytes. 310 x 240 pixels.


    N1 Flight Test Begins - 1968-1969

    By the end of summer the first N1 launch pad (LC110R) was completed. In addition to the sixteen flight vehicles, two N1 mock-ups were being built to support pad compatibility tests. Assembly of the first 1M1 mock-up was nearing completion at the MIK assembly building at Baikonur. In September 1967 the EU-28and EU-29 test models of the second and third stages began hot firing tests on their test stands at Samara. On 25 November 1967 the 1M1 mock-up was first erected on LC-110R. After tests of electrical and hydraulic interfaces on the pad it was returned to the assembly building on 12 December.

    A decree in November had recognised yet further slips in the schedule, with a first flight test of the vehicle not expected until the third quarter 1968. By March 1968 it was recognised that no Soviet manned lunar landing would take place until 1970. On May 7, 1968, eight months behind the 1966 schedule, N1 booster 4L was erected at launch complex 110R. Under its shroud was the 7K-L1S spacecraft. This modification of the 7K-L1 circumlunar Soyuz incorporated the Isayev forward propulsion module that would be used on the LOK and LK. A mass model representative of the LK lander was also included. These early test N1’s were limited to a lift-off mass of 2,735 tonnes and had an earth orbit payload of 70 tonnes. Even so it has taken 165 train wagon-loads of material to construct the vehicle, as against the 43 estimated in the 1962 draft project.


    N1 boattail assemblyN1 boattail assembly - Base of N1 first stage in assembly jig

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    A September 1968 flight test was planned. However the first stage oxidiser tank developed cracks during ground tests, and 4L was removed from the pad in June 1968. The first stage was cannibalised; the upper stages were incorporated into the 1M1 mock-up for further training of the launch crews. While the next N1, 3L, was being completed, this modified 1M1 was moved back to the pad for further ground tests and launch crew training. It remained there until the end of September.

    Returned to the MIK, the flight payload taken from 4L, the 7K-L1S, was integrated with the 1M1. The 1M1-L1S was moved back to the pad in November to conduct tests of the payload. It was joined by 3L, erected on launch pad without its payload (which was on the 1M1 mock-up). This was the first, but not the last, dual N1 roll-out. 3L was put through a series of engine system tests. In January 3L was returned to the MIK and the L1S payload was integrated to the launch vehicle. Also under the L3 payload shroud was an LZS functional test model of the LK.


    N1F - SrN1F - Sr - N1F with Sr Lox/LH2 upper stage

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    The first 28 day long N1 countdown began in January with the roll-out of 3L to the pad. Mishin personally led 2,300 technicians in around-the-clock shifts to prepare the vehicle for its first flight. Fifty tanker cars of propellants were required to fuel the booster. The initial planned launch on February 20 was scrubbed because of weather. Finally, on February 21, 1969, N1 serial number 3L rose into the sky, thundering over the roofs of the assembly worker’s apartments as they cheered it on. But trouble was afoot. Small metallic particles lodged in the gas generator turbine of engine 2. This resulted in a rising high frequency oscillation, eventually causing some engine components to fatigue and tear off their mounts. A forced leak of propellants followed, setting in motion a fire in the tail compartment. The KORD's BKS engine monitoring system detected the fire, but then gave an incorrect signal shutting down all engines at 68.7 seconds into the flight. The vehicle was destroyed by range safety 1.3 seconds later. The SAS escape tower worked as designed and the 7K-L1S capsule was recovered. The main body of the rocket impacted 45 km downrange from the launch pad. British intelligence detected the launch attempt, but the CIA's technical means for some reason missed it and they denied for years that it had ever occurred.


    N1M 1974N1M 1974 - N1M of 1974

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    The failure of the KORD was attributed to the much higher than expected temperatures in the engine compartment. The next vehicle, 5L, was modified by having the KORD moved to the intertank compartment. Additionally, ventilation openings to the engine compartment were introduced below the fuel line fairings.

    Against this failure, the Apollo program was achieving success after success in bimonthly missions. While beating the Americans to a moon landing was now clearly impossible, a dual unmanned mission was devised, which, if successful, would have stolen a little of the American’s thunder. The plan was for the next N1 to launch an unmanned 7K-L1S spacecraft on a loop around the moon. It would take multi-spectral photographs of the lunar surface and far side. Meanwhile, a Proton rocket would launch an unmanned Ye-8 soil return spacecraft. This would soft land on the moon, deploy a core drill which would take a small sample of lunar regolith. Deposited in a small spherical re-entry capsule, this then would automatically be returned to earth.


    N1M cutawayN1M cutaway

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    The unremitting three-shift work continued. To meet the schedule the modifications to 5L had to be made according to engineering sketches and red-lined drawings. Changes were verified on the 1M1 mock-up before metal was cut on the 5L. The modified vehicle 5L was finally launched on July 3 1969, just two weeks before the Apollo 11 first moon landing mission. It was a catastrophe. 5L already began to fail at 0.25 second after lift-off when the oxidiser pump of engine number 8 ingested a slag fragment and exploded. A fire ensued as the vehicle climbed past the top of the tower. The KORD reacted and engines were shut down in pairs until the acceleration dropped below 1 G; then the vehicle began to fall back to the pad at a 45 degree angle. The escape tower fired at the top of the brief trajectory, taking the L1S descent module away from the pad. Upon impact of the base of the N1 with the pad, the vehicle exploded with the force of a small nuclear bomb, destroying launch complex 110R. US weather and meteorological satellites revealed the disaster to the US intelligence agencies, and word soon spread through the government.


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    The investigation of this failure would result in substantial modifications to the N1 and it would be two years until the next launch attempt. The accident investigation commission came to three main conclusions: the engines must be redesigned with filters to prevent ingestion of metal splinters and shavings into the turbine machinery; the KORD logic must be modified to prevent unnecessary shut down of engines; and the launch vehicle trajectory had to be modified so that it moved away from the pad as soon as it cleared the tower.

    With the moon race lost, the rationale for further development of the limited 7K-LOK and LK spacecraft for a dash to the moon disappeared. The LK would be test flown in the coming years, but the LOK never was. Mishin instead looked towards using the N1 to establish a moon base (LEK - Lunar Expeditionary Complex).

    Redesign and New Missions - 1969 to 1974

    The three-year job of rebuilding Pad 110R began on August 3, 1969. By September 24 an N1 was erected on launch pad 110L to test the launch pad interfaces. This all-white launch vehicle, with no payload, was either the N1 mock-up 1M1 or flight vehicle 6L. This was the first use of the all-white paint job - the previous grey and white scheme had resulted in summer temperatures of up to 60 degrees Centigrade in the intertank compartments.


    N1F - 1974N1F - 1974 - N1F - 1974 Configuration (N1 s/n 8L)

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    It was not until May 18 of 1970 that US reconnaissance satellites detected another N1 being installed on the pad. Again with no payload, it remained there at least through 4 June.

    Against these failures, development was already underway to develop more powerful versions of the N1 to launch heavier payloads to the moon. The N1 growth study S. P. Korolev had signed shortly before his death had foreseen the wide use of oxygen-hydrogen propellants in modified versions of the N1 launch vehicle.

    It will be recalled that the 1965 study foresaw development of a Block V-II Lox/LH2 replacement for the Block B second stage of the N1. At OKB-276 N. D. Kuznetsov led a project to develop a liquid oxygen/liquid hydrogen version of the NK-15V engine with a flight thrust of 200 tonnes for use in this modernised version of the second stage of the N1. However Kuznetsov was having enough difficulty in completing satisfactory development of the conventional version of this engine for use in the basic N1 and his 200 tonne engine did not reach the hot firing test stage.


    N1 and N-1MN1 and N-1M - N1 and N-1M Dynamic test models

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    While these more ambitious plans would not be realised, the collectives OKB-2 (A. M. Isayev) and OKB-165 (A. M. Lyulka) were continuing studies and basic development that had begun in 1961. The first Russian use of hydrogen as a fuel was planned for rocket stages of relatively small size (with up to 50 tonnes of fuel). These stages, which were designated Block S and Block R, were to be introduced in place of N1 Blocks G and D as part of a modernised L3M lunar spacecraft complex. Use of oxygen-hydrogen propellants would permit expeditions to the moon of three crew, of which two would walk on the surface of the moon.

    Isayev set about adapting the 11D56 engine, with a vacuum thrust of 7.5 tonnes, for the Block R. This engine had originally been designed in the early 1960's for use in the third stage of an uprated Molniya-L launch vehicle. The new Block R for the N1 was to have an empty mass of 4.3 tonnes, a maximum fuel load of 18.7 tonnes, and would have been 8.7 m long and 4.1 m in diameter.


    N1-L3 Payload ShroudN1-L3 Payload Shroud

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    Lyulka developed two variants of a 40 tonne engine - the 11D54 (with fixed chamber) and 11D57 (with gimballed chamber). These would be used for the new Block V-III third stage of the N1 (3 to 6 11D54) and in the Block S (one 11D57).

    First hot firings of the 11D56 on the test stand began in June 1967. Both the 11D56 and 11D57 engines successfully completed their state development test series.

    At the Tsniimash museum in Korolev a photograph is displayed of a dynamic test model of an N1 configuration that has been called N1M. This model shows an N1 first stage, with a Block V-III second stage, and Blocks S and R third and fourth stages. Calculations indicate that a two stage Block A / Block V-III N1 would have a low earth orbit payload comparable to that of the basic N1 (around 95 tonnes). Evidently this configuration was considered as an alternative to a conventional three stage N1 for launching the L3M complex into low earth orbit.


    N1 on pad at nightN1 on pad at night

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    The original draft project for the new N1M-L3M lunar landing complex anticipated use of a two-launch profile. On the first launch a Block R RTB braking stage would be put on a translunar trajectory. The RTB would place itself in lunar orbit. Next, the manned L3M lunar lander would be launched. This new spacecraft was much larger than the LK, with a mass of 21 tonnes landed on the lunar surface. The L3M would dock, tail-first, with the RTB stage in lunar orbit. The RTB would act as a lunar crasher stage. The L3M would separate from the RTB just over the lunar surface, then hover to a soft landing. The crew would spend up 16 days on the surface. Following completion of their work, the landing legs would be left behind, and the L3M would launch itself on a trans-earth trajectory. Just before arrival at earth, the crew would enter their Soyuz capsule, separate from the L3M, and make a lifting re-entry into the earth’s atmosphere. It was felt that within the existing funding allocation of the original N1-L3 programme, enough N1’s would be available to support a series of landings in 1978-1980.


    N1 5L RolloutN1 5L Rollout

    Credit: © Mark Wade. 25,330 bytes. 406 x 287 pixels.


    In July 1970 Kuznetsov was given authorisation to design substantially improved versions of the N1 rocket engines. These would include filters in the propellant lines to prevent ingestion of debris in the turbo-machinery; improved vibration isolation; autonomous operation; and many detailed reliability and durability improvements. So substantial were the changes that they received a completely new series of designations (NK-33, NK-43, NK-39, NK-31 in place of NK-15, NK-15V, NK-19, NK-9V). However it would take over three years of design, development, and test before these new engines would be available.

    The N1 that would utilise these engines was designated the N1F (this had no relation to the much more powerful N1F design of 1965 - it was more like the N1U 'perfected' N1 design of the same year). With a payload to a 225 km orbit of 105,000 kg, the N1F would use the new engines, higher density superchilled propellants in all stages, lighter stage structures and numerous detailed changes. Following extensive wind tunnel studies, the boat tail was again redesigned in detail to cope with gas dynamics problems. A cylindrical base reduced the vehicle maximum diameter from 16.9 m to 15.8 m. Four high-thrust roll 'steering' engines were later added to prevent the loss of control that would destroy the 6L launch vehicle. The KORD was completely redesigned, a fire extinguishing system was installed, improved isolation of cabling and electronics was introduced. The telemetry system was reduced in weight while increasing the number of points measured from 700 to 13,000.


    N1 3L on padN1 3L on pad

    Credit: RKK Energia. 16,703 bytes. 236 x 283 pixels.


    Full go-ahead to develop a liquid hydrogen/liquid oxygen high energy upper stage for the N1F finally came in June 1970. The decision was made to develop a multi-engine Block Sr with a propellant mass of 66.4 tonnes. This single stage would be used in place of the previously-planned Blocks S and R to insert spacecraft of the Lunar Expeditionary Complex (LEK) into low lunar orbit. It was also to be used to insert heavy spacecraft into geosynchronous orbit and on interplanetary trajectories. The increased payload of the N1F, combined with the Block Sr stage, would allow a single N1F launch to place 27 tonne spacecraft on the lunar surface. The L3M lander could be increased in capability to allow three month stays on surface.

    It was decided to incrementally test the planned changes for the N1F lower stages, but using the old engines. Vehicle 6L was substantially improved, incorporating filters in the propellant lines to prevent any foreign objects from getting into the pumps.. The shape of the tail of the booster was modified, and ventilation and refrigeration systems were added to keep the engine compartment cool. It was rolled out with the all-white paint scheme. A planned June 23, 1971 launch was delayed for three days by heavy rain. On June 27, almost two years after the last attempt, N1 serial number 6L thundered into the sky. After lift-off and ascent, the vehicle made the new evasive manoeuvre to move away from the pad. The axial rotation this started was aggravated by the by gas dynamics interactions of the thirty engines with the air slipstream. The launch vehicle developed a roll beyond the capability of the control system to compensate. 6L began to break up as it went through Max Q. Control was lost at 50.2 seconds into the flight and it was destroyed by range safety a second later. The main body of the rocket impacted 20 km downrange. However the engines functioned well and did not shut down up to the point of vehicle destruction. No functional payload was carried and this launch did not have a working launch escape system. Although still counted as a failure, the technical difficulties were being solved one-by-one.


    N1 vehicle 7LN1 vehicle 7L

    Credit: Ed Cameron. 33,258 bytes. 271 x 475 pixels.


    Work on advanced payloads for the N1 continued. It may be recalled that the N1 draft project of 1962 spoke of 'establishment of a lunar base and regular traffic between the earth and the moon'. Korolev raised the matter informally at tea with Chief Designer of rocket complexes Vladimir Pavlovich Barmin, head of GSKB SpetsMash (State Union Design Bureau of Special Machine-Building). Barmin was interested in pursuing the subject, but questioned how could such a base be placed on the moon. 'You juste design the base', Korolev assured him, 'and I'll figure out how to get it there'. The project was known to SpetsMash as the 'Long-term Lunar Base' (DLB) and to OKB-1 as 'Zvezda'. Consideration was given to using the same elements in expeditions to other planets. Under the DLB studies SpetsMash defined the purposes of the base, the principles of its construction, phases of its deployment and composition of its scientific and support equipment. The enthusiasts that worked on the project at SpetsMash were naturally known as 'lunatics'.


    N1 5L night launchN1 5L night launch

    Credit: RKK Energia. 9,417 bytes. 291 x 480 pixels.


    Zvezda would have utilised unmanned spacecraft designed by the Lavochkin OKB to conduct initial reconnaissance of the prospective moon base site. These would use lunar soil core drills to obtain samples of the soil and return them to earth for analysis, and Lunokhod rovers to survey the site. If the site was found to be satisfactory, these craft had radio beacons which would guide follow-on elements of the base to precision landings.

    Ambitious articulated mobile nuclear-powered Lunokhod laboratories would take the cosmonauts from the landing sites on long-duration traverses of the lunar surface. The Lunokhods were equipped with core samplers and manipulators so that the crew could conduct collection of surface samples from within the pressurised cab without the need to always exit the ship and conduct surface operations in space suits. One of the main objectives of the base would be the location and mining of Helium-3 for use in nuclear fusion reactors on earth. Rare on the earth, Helium-3 was abundant on the moon, having collected in the regolith from the solar wind.


    N1 Stage 1N1 Stage 1 - Views of computer model of N1 first stage

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    Barmin's lunar base would be crewed by nine cosmonauts and consist of nine modules. These modules would have a length of 4.5 m during launch and transport on the moon. Once position in place on the surface of the moon and inflated with air, they would telescope out to 8.6 m length with a total floor area of 22.2 square metres. Power would be provided by nuclear reactors.

    The nine modules would be pre-equipped in the factory for specialised functions: command module, laboratory/warehouse module, workshop module, midpoint module, medical/gymnasium module, galley module with dining room, and three living modules.

    In later versions, the manned elements apparently used the improved L3M complex (designed for the follow-on two man lunar landings) to ferry manned crews from earth orbit to lunar orbit and then from lunar orbit to the surface and back. The Block Sr LOX/LH2 stage would be used to insert the components of Zvezda into low lunar orbit.


    N1 7L on padN1 7L on pad - Note modified first stage fairings on N1 7L

    Credit: RKK Energia. 31,432 bytes. 413 x 283 pixels.


    By 1971 the lunar city project was practically complete and Chief Designer Barmin arranged a meeting with Secretary Ustinov, head of all military and space rocketry. He brought along two of this 'lunatics', Aleksandr Yegorov and Vladimir Yeliseyev. The project was defended in a marathon meeting - nine presentations over six hours. At the conclusion, Ustinov agreed that the project should go ahead - but he couldn't decide, at the pace of a walk or the speed of a freight train. In the event, the point was moot.

    In the second half of 1972 and first half of 1973 TsKBEM began technical development of a Multi-module Orbital Complex (MOK). This was an integrated earth orbit infrastructure of space stations, free-flying modules, and massive geostationary satellites. It harked back to Korolev’s ‘Orbital Belt’ scheme of a decade earlier. The N1 would be used to launch the two main components of the MKBS Multi-module Cosmic Base Station into a sun synchronous 450 km orbit at 97.5 degrees inclination. The N1/Block Sr combination would be used to place enormous communications platforms into geosynchronous orbit. It was foreseen that in the later stages of the MOK the ultimate derivative of the N1 would provide reusable logistic support to the station. This would be a single-stage-to-orbit modification of the N1 Block A stage using a combination of air-breathing LACE (Liquid Air Cycle Engines) booster engines and liquid hydrogen/oxygen propellant sustainer engines on the core. This ultimate N1 was one of several versions sketched by Soviet engineers for US intelligence operative Peter N James in 1972-1973.


    L3 CutawayL3 Cutaway - Dimensioned Russian cutaway drawing of L3 manned lunar landing complex.

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    Meanwhile the test flight series continued, albeit at a slow rate. N1 serial number 7L incorporated most of the changes expected for the N1F, except for the new engines, which were still not available. Payload for this mission consisted of a (now obsolete) 7K-LOK lunar orbiter and an LK functional model. The launch of 7L came on November 23 1972. The rocket ascended into the sky, and the engines ran 106.93 seconds, only seven seconds before completion of first stage burnout.

    At this point, to reduce the G forces on the vehicle, a programmed shutdown of six engines occurred. Immediately thereafter, the oxidiser pump of engine number 4 exploded. The vehicle was destroyed by range safety before the second stage could separate and begin operation. The root cause was never determined. Mishin blamed the engine designers. Kuznetsov claimed that they were not at fault, saying the shutdown of the central engines had led to propellant line hammering, followed by rupture of propellant lines, resulting in the explosion of engine number 4. All agreed that if the N1 first stage had simply been shut down, and Stage 2 ignited, a successful mission could have followed.

    N1 with Aerospike First Stage Engine

    While the first N1F vehicle had yet to fly, studies continued on a number of improved N1’s. One of these contemplated the use of an aerospike engine in the first stage. Two variants were considered. In the first, the 30 x 151 tonne thrust NK-15 engines of the first stage were replaced with 24 x NK-15F engines of 188 tonnes thrust. This freed up the centre of the stage for a truncated aerospike. As in similar designs advocated by Philip Bono in the United States, hot gas would be bled off from the engines to produce an ‘aerospike’ streaming behind the booster, which would contour the combined rocket exhaust into an optimum flow. The advantage of the aerospike was that it ‘auto-corrected’ for altitude, providing optimum specific impulse over a range of conditions.

    The second variant eliminated the NK-15’s completely and used a radical annular combustion chamber that surrounded the aerospike. Detailed mass calculations were made for each variant. The final study found that an improvement was achieved - but probably not one that justified the development expense and risk. The empty mass of the stage increased because the central body of the aerospike and the exhaust gas system were all additional features. Further, the NK-15’s were closed cycle engines. Bleeding hot gas from them for the aerospike actually reduced their inherent specific impulse.

    For Variant A, a substantial development program would be required to increase the NK-15’s thrust by 24%. Variant B required an even bigger program, and learning how to vector the thrust of the annular engine (by diverting even more hot gas from the engines) for rocket steering would take a lot of flight test experience.

    The final conclusion of the study was that the improvement in performance was not worth the development risk in three-stage, low specific impulse designs such as the basic N-1. Using the ‘standard’ N1 second and third stages, payload was increased only 5.0% for Variant A and 6.9% for Variant B. It was concluded that the aerospike could provide bigger performance gains in single- or two- stage-to-orbit designs or in upper stages.

    The final design comparison was as follows:

    Parameter Basic Block A Aerospike Variant A Aerospike Variant B
    Calculated Lift-off Thrust, kgf 4,530,000 4,511,400 4,510,500
    Effective Lift-off Thrust, kgf 4,117,000 4,420,000 4,480,000
    Vacuum Thrust, kgf 5,065,500 5,334,400 5,379,000
    Fuel Consumption, kg/sec 15,304 15,241 15,238
    Calculated Specific Impulse, Lift-off, sec 296.0 296.0 296.0
    Effective Specific Impulse, Lift-off, sec 269.0 290.0 294.0
    Specific Impulse, Vacuum, sec 331.0 350.0 353.0
    Specific Impulse, Average, sec 311.0 321.0 324.3
    Stage Empty Mass, kg 112,230 120,250 124,700
    LEO Payload, kg 92,700 97,350 99,090

    The Last Days

    Following the fourth N1 failure, Glushko and Kosberg were brought in to provide independent opinions on how the problems could be solved. Neither came up with inexpensive solutions. Kosberg wanted to equip the rocket with new-development 250,000 kgf engines using N2O4/UDMH. Glushko suggested using the RD-253 engines that he had developed for the UR-500 Proton launch vehicle. Interestingly, this very successful design was the final form of the RD-250 engine that Korolev had rejected for the N1 ten years earlier. But even Glushko had to admit that using the RD-253 would mean converting the N1 to N2O4/UDMH propellants, thereby lowering payload performance to unacceptable levels (just as Korolev had argued). Glushko was also rather dubious of successfully synchronising the operation of 30 engines.

    The cash-starved project continued to limp along. Funding to proceed with design and construction of the L3M was not forthcoming. But Kuznetsov’s new series of engines had been subjected to huge amounts of ground testing. First/second stage engine testing was completed in September 1972 and third stage testing in November 1973. The next vehicles, 8L and 9L, would be the first to use these new modernised series engines and fully reflect the N1F configuration. The plan was that both 8L and 9L would be launched in the fourth quarter of 1974 in a demonstration of the N1F-L3M dual launch scenario. Confidence was high, based on the massive telemetry received on the 7L flight, that all problems had now been rectified.

    On May 18, 1974 the Minister of Medium Machine Building Afanasyev attended a routine meeting of the management of OKB-1. In a few clipped sentences he informed the group that the Politburo had decided to remove Mishin, replace him with Korolev's old nemesis Glushko and combine the two OKB’s into a new entity known as NPO Energia. Afanasyev wished the stunned managers every success, and left the room. The N1 program was cancelled.

    The N1- the Accounting

    Two fully assembled (serial numbers 8L and 9L), and four partially assembled N1Fs were available at time of cancellation. In all, Kozlov’s Progress factory in Samara had delivered components for ten flightworthy N1’s, plus the two mock-ups, the engine test stand versions of the upper stages, and several other static test specimens. A total of 3.6 billion roubles was spent on the N1-L3 program, of which 2.4 billion roubles went into N1 development. Another 1.37 billion roubles would have taken the programme to completion, including construction of a final total of sixteen flight N-1’s, as laid out in the decree of 1964.

    The Soviet Union had lost the moon race. In retrospect this seemed inevitable given a three-year later start and a funding level only a fraction that of the Apollo program. Those on the project felt that they were within months of finally providing the Soviet Union with a heavy-lift booster. Instead the work was discarded, and Glushko began design of the Vulkan launch vehicle with an entirely new configuration and engines. This was itself revised on 17 February 1976 when Glushko was directed to modify Vulkan to the Energia configuration to accommodate the Buran space plane (based on US Space Shuttle). Thirteen years and another 14.5 billion roubles later, the Energia flew, only to be cancelled in turn with the collapse of the Soviet Union.

    Like a Phoenix, at least parts of the N1F may still fly. The 150 NK-33, NK-39, and NK-43 engines built by Kuznetsov were cocooned and secretly stored at the program's cancellation despite orders to the contrary. After Glushko's death, these were considered for use in the American Atlas IIIA launch vehicle, but eventually sold to Kistler Aerospace for its reusable US launch vehicle 22 years later. The 11D56 Lox/LH2 engines designed for the Block Sr RTB stage for the L3M also never flew, but the design was sold to India in 1994 for use in its GSLV launch vehicle.

    The N1's themselves were broken up in 1975 and the payload shrouds and tank bulkheads used as carports, storage sheds, and sun shelters around the cosmodrome. Today the N1 worker’s city of apartment blocks is empty, and tumbleweeds grow among the N1 components at the abandoned recreation centre. The launch pads are crumbling, the desert slowly reclaiming the colossal works of the project. The rest is silence.


    References

    • Przybilski, Olaf, and Wotzlaw, Stefan, N-1 Herkules - Entwicklung und Absturz einer Traegerrakete, Schriftenreihe der Deutschen Raumfahrtausstellung e.V., 1996.
    • Rusakov, K, "’Aerospaik’ dlya N-1", Novosti kosmonavtiki, Number 7, 1998, p. 27.
    • Semenov, Yu. P., Raketno-Kosmicheskaya Korporatsiya ENERGIYA imeni S. P. Koroleva 1946-1996, RKK Energia, 1994.
    • Vetrov, G S, S. P. Korolev i evo delo, Nauka, Moscow, 1998.

    Other N1 web sites as of this writing are listed below. Note however that the older the article, the more likely that some of the information has since been found to be incorrect....
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    Last update 12 March 2001.
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