Nositel (N) -1 |
The originally N-1
was intended to launch heavy satellites into Earth orbit. In consisted of three
stage all using liquid oxygen and kerosene propellants. The N-1 heavy-lift contained
six spherical tanks (two on each of the first three cone-shaped stages), the fuel
tank being above the oxidiser tank. These tanks were produced from magnesium-nickel
alloy AGM6, and the N-1 external construction was duralumin D16.
The first stage , Block A, had 30 engines, arranged in circles of 24 and 6. The
engines NK-15 were
developed by the Kuznetsov Design Bureau. The engines could not be gimballed to
steer the vehicle. Instead, the motors were selectively throttled to achieve the
correct trajectory. The 30 main engines (+4 drive engines) have a thrust of 154
tons each and burning 150 seconds. The first stage had a 12.9 m diameter LOX
tank and a 10 m diameter fuel tank. On the lower part of this stage were installed
4 grating-type stabilizers.
The second stage, Block B, featured 8 Kuznetsov engines
NK-15V. The engines differed
slightly from those on the first stage in that they had longer nozzles for better
performance at higher altitudes. Again , guidance was achieved through selective
throttling. The 8 engines have a thrust of 179 tons each. The second stage
had a 8 m diameter LOX-tank and a 7 m diameter fuel tank.
The third stage, Block W, employed four engines
NK-19 (later
NK-39) of different design.
The third stage engines could be gimballed and have a thrust of 41.5 tons each.
The stage had a 5.8 m diameter LOX tank and a 4.7 m diameter fuel tank.
This was the basic N-1 vehicle. The lunar program required the addition of two more
rocket stages, a lunar lander and a spacecraft for the return to Earth. These components
came under the name L-3. The program as a whole was known as N-1/L-3.
The next stage (Block G) concerned the lunar spacecraft and had a total mass to
98 tons. Each block had only one engine NK-21
(later NK-31),
a toroidal fuel tank and a cylindrical oxidiser tank. This block is for acceleration
and next Block D (engine RD-58)
for deceleration near the moon. The last was connected with Lunar Orbital
Cabin (LOK) and Lunar Cabin (LK). On the top of the N-1 booster was installed a
10 m long solid rocket launch escape system with a mass of 7 tons. The L-3 composition
is 43.7 m long, the total booster mass is 2.788 tons.
The N-1 booster had a built-in safety failure system (KORD) which controlled each
engine in each stage. If 4 engines in the first stage failed the rocket would
still work, likewise, if a pair of engines in the second stage or one engine in
the third stage failed, the N-1 was still capable of reaching low Earth orbit.
The N-1/3L was
finally ready for its first test flight in 1969. The booster was to carry a Soyuz-LOK
and a mock-up of the Lunar Cabin, but 70 seconds after lift-off on February 21 the
rocket failed:
The first N-1 booster lifted off on 21.02.1969. First stage ignition occurred at T-4 seconds. Engine no.12 and 24 shutdown after 3-7 seconds because of on error in the KORD control system. The flight was able to continue because the remaining engines compensated for the failure. At T+25 seconds the engines were throttled down until the vehicle safely passed through the period of maximum dynamic pressure. At T+65-66 seconds the engines throttled back to full power but the much faster than had been expected causing strong vibration. The oxidiser pipeline of one engine broke spilling liquid oxygen and a fire broke out. All first stage engines were apparently shut down at T+70.
A second launch attempt was made on 03.07.1969. Soon after ignition (6-9 seconds) one of the oxidiser pumps failed, causing the engines to shut down. The rocket fell back towards the launch pad. The launch escape system worked well and the payload was delivered.
The third launch took place on 27.06.1971. Soon after lift-off at a altitude of about 250 m and 8-10 seconds after ignition the booster guidance system failed and an unplanned rotation about the vertical axis began, causing breakup of the support structure between the second-third stages.
The last launch attempt took place on 23.11.1972. The N-1 first stage engines worked well to 107 seconds, but then an unexpected vibration began in the first-second stages causing flight termination about 40 seconds before first stage engines normally shut down. The booster exploded.
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In July 1970, Kuznetsov received an order to develop significantly improved engines for the first and second stages of the N-1. However, it was to take another three years before these engines, designated NK-33 and NK-43, were available. They could at first time be used for the N-1F.
Finally five improved NK engines was developed by Kuznetsov:
The new NK-33 and NK-43 engines for the N-1F (upgraded versions of the NK-15 and
NK-15V).
The NK-31 and NK-39 engines (upgraded versions of the NK-21 and NK-19) and already
available for the N-1 (6L and 7L).
Two of the N-1F launcher (8L and 9L) had been fully assembled and readied on pad for flight. But in 1974 the program was cancelled. The two N-1F launcher were scrapped, the engines had previously been removed.
Note: LH2/LOX engines for an upgraded
variant N-1M:
The RD-57 (11D57) LH2/LOX engine was developed as a replacement
for the NK-31 and NK-39