The history of the N-1 program.

The Initial Stages

On June 23, 1960 the USSR gave the go ahead to the N-1 project via a decree: "On the Development of Powerful Launch vehicles, Satellites, Spacecraft, and Space Exploration 1960-1967". This was Sergei Korolev’s design for a family of launchers, the key one being the largest, the N-1.

This initial design while a powerful heavy lift rocket, had a planned payload capacity of 75 tonnes - a lot less than that for a lunar landing mission. Korolev was thinking flyby missions of Mars, which require a much lighter payload.

It was to use liquid-propellant engines, working on oxygen-kerosene on all stages. Launch mass with the payload was 2200 t.

But note that date  almost a full year before the flight of Yuri Gagarin.

But even before this date, there had been major disputes and changes. Originally Sergei Korolev had approached Valentin Glushko to design the engines for his heavy lift rocket. The men had previously been friends, but heated arguments broke out over this project.

Glushko was easily the most experienced rocket engine designer in the USSR, and he demanded the use of advanced propellants like hypergolics. Korolev thought that these were dangerous, and much too difficult to handle. They had a blazing row in front of the politburo, and Glushko point black refused to work on the project.He took the whole thing very personally, and never forgave Korolev for this perceived insult.

Korolev had to find someone else to make his rocket engines.

He chose Nikolai Kuznetsov, who had considerable experience building jet aircraft engines, but had not built a rocket engines. Because it is a lot harder to build a big rocket engine than a small one, Kuznetsov’s solution had a large number of smaller engines. It also required a complex system, KORD, to control the engines. This was to prove a major issue in flight.

Despite problems that came to light later, there are many advantages to this design. Apart from simpler and easier to develop engines, a wide base with a ring of engines around the edge means it is practical to steer the whole rocket by throttling the engines.

Korolev wanted to store the propellants in spherical tanks, which would be easy to make strong. The required relative size of the oxygen and kerosene tanks lead to a conical design for each stage, and this combined with the ring of engines gave the N-1 its distinctive design. This is very different from more modern designs, (and the Saturn V), where the structure is much more flimsy and the tanks form part of the structure - giving great savings in the weight.

The main visible design difference at this stage was that the first stage lacked the inner ring of 6 engines.

Make notes on changes before the first launch, to increase payload.

Notes on the design - engines good, KORD bad.

The first launch.

Changes made after the first launch.

The second launch, pad destruction.

Changes made for the 3rd launch.

3rd launch.

Changes made for the 4th launch.

4th launch.

N1-8L and the end of the program.

There were four attempts to launch an N-1 rocket, each ending in an explosion with complete destruction of the craft. (Details below taken from Wikipedia)

•    February 21, 1969: Exploded at 12,200 m altitude, 69 seconds after lift-off.

•    July 3, 1969: At lift-off a loose bolt was ingested into a fuel pump, which failed. After detecting the inoperative fuel pump, the automatic engine control shut off 29 of 30 engines, which caused the rocket to stall. The rocket exploded 23 seconds after shutting off the engines, destroying the rocket and launch tower in the biggest explosion in the history of rocketry.

•    June 24, 1971: Vehicle serial number 6L - experienced an uncontrolled roll immediately after lift-off beyond the capability of the control system to compensate; the vehicle was destroyed 51 seconds after lift-off at 1 km altitude.

•    November 22, 1972: Vehicle serial number 7L - the engines ran for 106.93 seconds after which Pogo oscillation of the first stage caused engine cut off at 40 km altitude; a programmed shutdown of some of the engines to prevent over-stressing of the structure led to an explosion of engine number 4. The vehicle disintegrated.

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