Rocket-Space Complex N1-L3 being transported to the launch site

Rocket-Space Complex N1-L3 at the launch pad

Rocket-Space Complex N1-L3 being installed on the paunch pad

Pre-launch processing of Rocket-Space Complex N1-L3 at the launch pad

Two rockets N1 at the launch site

Rocket-Space Complex N1-L3 in flight

The first launch of complex N1-L3 carried out on February 21, 1969 was accidental. As a result of high-frequency vibrations in the engine №2 gas generator, a pressure reducing connector behind a turbine broke off and leakage of components occurred that caused a fire in the aft compartment and violated the engine control system operation that commanded to shut down engines at 68.7s.
Despite the accident, this launch has proved the validity of the dynamic profile, launch dynamics, LV control processes using the engine thrust misalignment and permitted to obtain test data on LV loads, strength, the LV and launch system exposure of acoustic loads, and other data including operating conditions in real environment.

The second launch of complex N1-L3 carried out on July 3, 1969 and was also accidental because of faulty operation of engine №8 of stage A. A certain cause of the accident was not established. The Accident Committee headed by V. P. Mishin concluded that the most probable cause of the accident was a destruction of the engine oxidizer pump at a transition to the full thrust.
Two years required to analyze the test results, perform studies, and experiments. As a result, proper measures were taken that allowed to exclude all expected causes of the accidents, enhance reliability of engines, other systems and equipment, as well as to secure the launch pad. The primary measures were: the oxidizer pump reliability enhancement; installation of filters in front of the engine pumps to avoid ingress of foreign matters; pre-launch filling and in-flight purging of the stage A aft compartment with nitrogen; introduction of a freon fire extinguishing system; adding of thermal protection for the structure elements, instruments, and cables of systems accommodated in the stage A aft compartment; introduction of engine ignition command inhibition till 50s of flight and the LV emergency escape from the launch site at power disconnection, etc.

The third launch of complex N1-L3 took place on June 27, 1971. All 30 engines of stage A were switched to the preliminary and full thrust modes as consistent with a nominal timeline and were normally operating till their switchdown was commanded from the control system at 50.1s. However, from the beginning of flight, anomalous roll stabilization was observed and a spin angle misalignment was increasing and by 14.s achieved 145°.n As far as the engine emergency shutdown command was inhibited till 50s, the flight was actually not controlled till 50.1s. The most probable cause of the accident was an effect of not previously considered disturbances exceeding the roll control moments. For the rocket roll control, in less that a year, steering verniers were designed that used producer oxidizing gas and fuel taken from main engines.

On November 23, 1972 the fourth launch of complex N1-L3 was carried out. The rocket employed for this launch was considerably modified to eliminate the revealed drawbacks and increase the payload mass. The flight was controlled by the onboard Data Management System on commands from gyrostabilized platform (A Chief Designer: N. A. Pilyugin). The propulsion units included steering verniers. A fire extinguishing system was introduced. Mechanical and thermal protection of instrumentation and cable system was improved, etc. The measuring systems were outfitted with a newly developed small-size radio and telemetry equipment (a Chief Designer: A. F. Bogomolov). In total, beyond 13 000 sensors were provided on the rocket.
The rocket has flied for 106.93s without comments, but 7s before the designed separation of stages I and II, an actually instantaneous breakdown of the engine №4 oxidizer pump occurred that caused the rocket destruction.
The next launch was scheduled for the fourth quarter of 1974. By May, relying on the analysis of previous flights and further studies, all design and measures focused on the rocket survivability. Assembly of modified reusable engines began. However, the Academician V. P. Glushko, appointed to be the Director General of NPO Energia in May 1974, by his order and a silent consent of the Ministry of Machinery, terminated all activities associated with complex N1-L3.
In total, by January 1973, expenses for the N1-L3 program reached 3.6 milliards of rubles of which the N1 development cost was 2.4 milliards of rubles ( at that time rate).
The Decree of the Central Committee of CPSU enacting to terminate work on complex N1-L3 and write the costs into losses was released only in February 1976. Thereupon, all rocket stages, pre-launch processing and measuring equipment were destroyed. Herewith, costs in amount of 6 milliards of rubles (at the 1970s rate) spent on the program were written into losses.
Although the experience gained in designing and manufacturing, operating and ensuring reliability of the powerful rocket system N1 has been employed in full measure in developing LV Energia and is likely to find wide application in future projects, it is impossible not to admit that cutting down of work on N1 was a mistake. Later on, to develop a rocket of a similar capacity required 13 years more and 14.5 milliards of rubles.