N1 (rocket)

N1
N1 mock-up for launch pad tests
Type:	heavy launcher
Country:	Soviet Union
Manufacturer:	OKB-1
construction
Height:	105.3 m
Diameter:	22.4 m
Dimensions:	2825 t
Stages:	5
stages
1st stage :	Block A
Engine :	NK-15, 30 pieces
Fuel :	RP-1 and LOX
Burn time:	125 s
2nd stage :	Block B
Engine:	NK-15V, 8 pieces
Fuel:	RP-1 and LOX
Burn time:	120 s
3rd stage :	Block V
Engine:	NK-21, 4 pieces
Fuel:	RP-1 and LOX
Burn time:	330 s
4th stage :	Block G
Engine:	NK-19
Fuel:	RP-1 and LOX
Burn time:	470 s
5th level :	Block D
Engine:	RD-58
Fuel:	RP-1 and LOX
Burn time:	600 s
Starts
Status:	inactive
First start:	February 21, 1969
last start:	November 23, 1972
Starts:	4th
Successes:	0
Failures:	4th
Starting place:	Baikonur 110
Starting capacity
Capacity LEO :	95,000 kg
Capacity moon :	23,500 kg

The Nositel 1 , or N1 for short ( GRAU index 11A52), was a launch vehicle that was developed as part of the Soviet manned lunar program .

Starting position

After the early successes of its space program, the Soviet Union also took part in the "Race to the Moon" alongside the USA . While all resources there for the Apollo program were concentrated on the Saturn rockets, two teams in the USSR were working in parallel on new rocket projects. One of them was the OKB -1 (today RKK Energija ), which developed the moon rocket N1 from 1959 under the direction of Sergei Koroljow . However, the original design by Korolev saw military use in the foreground. In the context of the use of the cosmos for military targets, also planned by the USSR at the beginning of the 1960s (government decree 715-296 of June 23, 1960), he used the N1 as a carrier for heavy reconnaissance satellites, defensive military payloads and as an offensive carrier for Strikes offered against any point on earth.

The development of the required powerful rocket engines proved to be problematic. The previous partner for engine development of Korolev's OKB-1, the OKB-456 of Valentin Petrovich Gluschko , now worked closely with the competing design office OKB-52 of Vladimir Tschelomei . Koroljow and Gluschko had hopelessly quarreled among other things about the engine construction (single-chamber versus four-chamber engine) and the fuel combination to be used ( RP-1 / oxygen versus UDMH / nitrous oxide ). Koroljow therefore cooperated with Nikolai Kuznetsov's OKB-276 , which until then had mainly developed air jet engines and propeller turbines - including the world's largest propeller turbine engine NK-12 with around 11,000 kW (15,000 hp). Due to the lack of experience with large rocket engines, the development of the engines took place with considerable delays.

technology

Representation of the N1 with the most important technical information

Representation of the N1 payload in section

Representation and size comparison of the Soviet and the American lunar spaceship

Representation of the Soviet and American lander in direct size comparison

The N1 was 105 m, the largest ever built Soviet rocket and in their dimensions and mass comparable to the Saturn V . Due to the low thrust of the Kuznetsov NK-15 engines (1.510 or 1.544 MN sea level / vacuum thrust), a large number of these engines had to be used in the first stage. So the N1 in their planned by Korolev original version with 24 engines in the first stage should be a payload of about 75 tonnes in low Earth orbit (Engl. Low Earth Orbit or LEO) bring. With a single launch, however, there was no manned mission to fly with a moon landing. Therefore, after Korolev's death, Mishin added six NK-15 engines to the design in the central section as the new project manager. To further increase the payload, he introduced cooling of the kerosene in the tanks and slightly modified the orbit parameters. This means that payloads in the LEO of a maximum of 90 to 95 t would have been possible. The N1 was, however, highly complex due to the engine arrangement and the associated fuel and control systems and proved to be very prone to failure. The total of 30 engines of the 1st stage were arranged in an outer ring with 24 engines (the original design by Korolev) and an inner ring with six engines (added by Mishin). Air was led between the outer and inner engine rings, which resulted in a kind of aerospike effect for the inner engines with higher fuel and thrust efficiency. However, the highly complex flow conditions of such a configuration in the speed range to be covered were completely underestimated.

The Kuznetsov engines NK-15 (1st stage) and NK-15W (2nd stage) were used in all flight tests. The first stage of the N1 achieved a total take-off thrust of around 43,300 kN. The engines were later developed into the Kuznetsov NK-33 (1.5102 or 1.638 MN sea level / vacuum thrust). The improved NK-33 (1st stage) and NK-43 (2nd stage) engines were available for use in the N1F modification from 1974 (LEO payload up to 105 tons), but never got off to a start due to the program being canceled in the N1.

At least eleven copies were planned, including a mock-up (N1-1M1) and ten airworthy missiles (N1-3L to N1-7L and N1F-8L to N1F-12L). The use of the improved NK-33 engines was planned from the test of the N1F-8L (in the improved version N1F) planned for August 1974. With the N1F-10L, the first manned Soviet moon landing was planned for around 1976.

Naming

The N1 missile never got a real name. The names Gerkules (Russian for Hercules ), Raskat , Lenin , Nauka or Gigant, which are occasionally mentioned in various publications, are purely speculative.

development

In May 1962, the unusual cone-shaped design with spherical tanks of a three-stage N1 was completed. It should have a launch mass of 2200 tons and a payload of 75 tons for the near-earth area. The project was approved by the Soviet government on September 24, 1962 and the deadline for implementation was set to be three years. 500 organizations from 26 ministries were involved in the project, which in the further course led to difficulties in project organization due to a lack of cooperation and coordination as well as competition.

On August 1, 1964, by decree of the Council of Ministers (655-268), the Soviet manned lunar program was finally split into two projects. With the designation LK-1 or later Zond a circumnavigation program ran in the OKB-52 of Chelomei. The OKB von Koroljow was awarded the contract for the moon landing with its project N1-L3. The first flight to the moon was ambitiously planned for November 1967. The rocket had to be redesigned for this, as a direct launch to the moon was planned, which increased the required payload to 95 tons. For this purpose, the first stage was supplemented by six additional engines, the spherical tanks were enlarged by cylindrical spacers and it was planned to refuel the kerosene in a cooled manner to increase the density. This increased the takeoff mass to 2,750 tons. After Korolev's death in January 1966, Vasily Mishin , who had played a key role in the reconstruction of the German A4 missile and the development of the first Soviet intercontinental missile Semjorka R-7 , took over the management of OKB-1. It quickly became apparent, however, that he lacked the political flair and skill of his predecessor - one of the reasons for the delays and the subsequent failure of the project. On February 4, 1967, Government Resolution No. 115-46 gave the Lunar Program the high priority and funding it had long demanded. So now the military provided a large number of workers to complete the ground work for the launch facilities. When launch pad PU 38 was completed in 1967, however, only a dummy (N1-2L also N1-1M1) of the rocket could be rolled to the launch pad, as the first rocket configured for a launch (N1-4L) was only available in 1968.

For reasons of time and costs, a test stand was not used for the entire first stage. Since the Baikonur complex could not be approached by heavy transporters, the N1 had to be dismantled and reassembled on site. So it happened that vibrations and flow problems of the propulsion gases were not correctly assessed before the flight. The position control around the longitudinal axis during operation of the first stage also turned out to be inadequate - the company dispensed with its own position control engines, the tasks of which were to be carried out by controllable exhaust nozzles of the turbo pumps. Only after the resulting crash of the third prototype were controllable engines used for roll stabilization.

Failed test flights

After all, the N1 did not successfully complete a flight. All four test flights between 1969 and 1972 ended in crashes - before the ignition of the second stage or the burnout of the first stage immediately afterwards. An unmanned experiment (N1-4L) planned for 1968 had to be canceled after the rocket had been erected because there were hairline cracks in the oxygen tank of the first stage.

• The first attempt at launch (N1-3L) took place on February 21, 1969. Just 0.34 s after take-off, the control system detected that the permissible speed of the turbo pump of engine 12 was exceeded due to an interference signal triggered by the ignition of pyrovalves. It switched off engines no. 12 and 24. After about 6 seconds, a pressure sensor at the gas generator outlet of engine no. 2 leaked. This caused gas at a temperature of around 340 ° C to escape. After 25 s another sensor leaked, this time above the inlet in the fuel line. Both streams came into contact. As a result, a fire developed in the rear of the rocket. The engine control system detected this fire (after about 54 s). After 68.7 seconds, the fire had destroyed the insulation of several cable harnesses, causing a large number of interfering signals to reach the engine control system. This then switched off all 28 engines that were still running. A modification 7K-L1S (s / n 3) of the 7K-L1 developed for the orbit around the moon was used as the payload. The SAS rescue system separated the spaceship before the explosion of the N1-3L, it landed safely on the parachute.

• The second attempt to take off (N1-5L) took place on July 3, 1969, just three weeks before the successful Apollo 11 moon landing, and ended in disaster. Already during take-off, a "foreign body" (suspected to be part of the pressure sensors in the oxygen lines) that got caught in a turbo pump (no. 8) running rapidly in pure oxygen caused it to explode. Some engineers also suspected direct contact between the high-speed rotor and the stator due to excessive manufacturing tolerances or overload. The automatic engine control then switched off 29 of the 30 first-stage engines after a total of about 15 s in a series of errors. The rescue system immediately carried the spacecraft 7K-L1S (s / n 5) out of the danger zone. With one engine still running, the rocket fell back at an increasingly inclined position from a height of 200 m and hit about 23 s after take-off. Numerous systems at the launch site were destroyed when the launcher exploded. As a result, the management of the launch complex categorically demanded that the N1 be swiveled to the side immediately after take-off for all future take-offs in order to protect it. In addition, it should never be possible to switch off the engines of the first stage within the first 50 seconds after take-off.

• The requested modifications were implemented for the third launch on June 26, 1971. For the first time, all 30 engines ran in the normal range. The N1-6L lifted off sideways due to the asymmetrical thrust of the main engines that was initially selected for its own particular purpose and then went into a climb. The aerodynamic peculiarities of this maneuver (lateral flow of the rocket and the initially asymmetrical exhaust gas jet) and the previously insufficiently known dynamic interactions of the exhaust gas jets of 30 engines running at full thrust resulted in a role that could no longer be controlled by the attitude control . Just 14 seconds after take-off, the roll angle exceeded the permitted deviation of 8 degrees. The shutdown of all engines initiated by the KORD was now suppressed by the filter required for forced operation of the engines in the initial phase. Between the 45th and 50th seconds after take-off, the increasingly strong rolling led to a loss of control around the other axes and the beginning of the structure's dismantling. The forced suppression of an automated shutdown of the engines ended according to plan after 50 s, whereupon the attitude control switched the engines off immediately in the 51st second. The missile was then destroyed by a radio command. The N1's limited roll stabilization was not originally intended for such complex lateral maneuvering. At least all of the engines in the first stage had worked satisfactorily in this attempt until they were stopped. This start attempt should only serve to qualify the delivery system. Dummies were therefore used as payloads, which is why the rescue system was also dispensed with.

• The fourth start of the largely improved N1-7L on November 23, 1972 ran smoothly until the six central first stage engines burned out. Their abrupt shutdown to avoid structural overload led to compression shocks in the fuel system, the rupture of at least one oxygen line, the explosion of engine no. 4 and ultimately the crash of the N1-7L after about 107 seconds. The explosion occurred just seven seconds before the planned separation of the first and second stages. Later analyzes showed that if engine no. 4 had separated about 2 s before the explosion, the airspeed and altitude achieved up to that point would have allowed the mission to continue successfully. However, such a scenario was never considered beforehand. For the first time, mockups of the lunar spaceship 7K-LOK and the LK lander, which has since been tested in the missions Kosmos 379, 398 and 434 in earth orbit, were carried along.

Effects

The plans for a manned Soviet moon landing were then postponed step by step and finally canceled in 1974. Wassili Mischin continued to work on the N1 in the hope of being able to use it, among other things, as a launch vehicle for the transport of a manned space station, comparable to the US Skylab . The entire N1 program was finally terminated in 1974 after the ZKBEM (formerly OKB-1) with the establishment of the production association RKK Energija on May 22, 1974 under the direction of Valentin Gluschko in this. This termination took place before a further test flight of the N1F-8L equipped with NK-33 was promising in the last quarter of 1974. At the time of the program termination, the N1F-9L was also largely completed. Both missions aimed at unmanned landings of the lunar lander LK. At this point in time, the first Soviet manned moon landing was planned for around mid to late 1975 with the N1F-10L. The 8L remaining in Baikonur was dismantled and many parts were used as building material in the city and its surroundings.

Technical specifications

• five-stage liquid rocket
• Start of development: 1960
• Starts: February 21, 1969 to November 23, 1972
• 4 starts, all of them were false starts (reliability: 0%)
• Height: 105.3 m
• Empty weight: 277 t
• Takeoff weight: 2750 t
• Total thrust: 43.3 MN
• Payload (LEO): 70 t (N1), later 95 t planned (N1F)
• Fuel: RP-1 (kerosene type) / liquid oxygen

Start list

This is a complete launch list for the N1 missile.

No.	Start time ( UTC )	S / N	Launch site	Type of payload	payload	Cause of the failure / crash
1	February 21, 1969, 9:18 am	3L	Ba 110R	Lunar probes and + model of the lunar landing complex L3	Zond (L1S), L3 model	Fire in the first stage, shutdown of the engines after 68.7 s and crash
2	July 3, 1969, 8:18 pm	5L	Ba 110R		Zond (L1S), L3 model	Destruction of a pump by foreign bodies in an oxygen line; Crash and explosion after 23 s with destruction of the starting device
3	June 26, 1971, 11:15 pm	6L	Ba 110L		LOK model, L3 model	Failure of attitude stabilization, self-destruction of the rocket after 50.9 s
4th	23 November 1972, 6:11 am	7L	Ba 110L		Zond (LOK), L3 model	Destruction of fuel lines after the 6 central engines burned out, engine no.4 exploded, crash after 106.9 s

literature

• Eugen Reichl: The N1 - Moscow's moon rocket. Motorbuch-Verlag, Stuttgart 2016, ISBN 978-3-613-03857-8 .

Web links

Commons : N1 (rocket)  - collection of images, videos and audio files

• Raumfahrer.net: The Soviet lunar program and the rocket N1
• Bernd Leitenberger: The Russian moon rocket N1
• N1 in the Encyclopedia Astronautica (English)

Individual evidence

1. ^ N1 in the Encyclopedia Astronautica , accessed on August 2, 2018 (English).
2. ^ Eugen Reichl: Typenkompass carrier rockets . 1st edition. Motorbuch Verlag, Stuttgart 2011, ISBN 978-3-613-03269-9 , pp. 44 .
3. ↑ Anatoly Zak: N1 Moon Rocket. In: Russian Space Web. July 21, 2018, accessed August 2, 2018 . 
4. ↑ FliegerRevue June 2011, pp. 42–45, Koroljow's last love: the moon rocket N1