N1 (rocket) - Launch History

Launch History

• February 21, 1969 – Vehicle serial number 3L – Zond L1S-1 (Soyuz 7K-L1S (Zond-M) modification of Soyuz 7K-L1 "Zond" spacecraft) for Moon flyby – Due to unexpected high-frequency oscillations in the gas generator, one of the pipes broke apart and a fire started. This fire reached the engine control system which at 68.7 s of flight sent the command to shut down the engines. The rocket exploded at 12,200 m altitude, 69 seconds after liftoff. The emergency rescue launch escape system was activated and did its job properly, saving the mockup of the spacecraft. All subsequent flights had freon fire extinguishers installed next to every engine.
• July 3, 1969 – Vehicle serial number 5L – Zond L1S-2 for Moon flyby – At liftoff 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 and also the largest manmade non-nuclear explosion ever (nearly 7 kilotons of TNT equivalent which equals to about 14,000,000 pounds.) The destroyed complex was photographed by American satellites, disclosing that the Soviet Union was building a Moon rocket. The rescue system saved the dummy spacecraft again. After this flight, fuel filters were installed in later models.It also took 18 months to rebuild the launch pad and delayed launches.
• June 26, 1971 – Vehicle serial number 6L – dummy Soyuz 7K-LOK (Soyuz 7K-L1E No.1) and dummy LK module-spacecrafts for Moon flyby – experienced an uncontrolled roll immediately after liftoff beyond the capability of the control system to compensate; the vehicle was destroyed 51 seconds after liftoff at 1 km altitude. This vehicle had dummy upper stages without the rescue system. The next, last vehicle had a much more powerful stabilization system with dedicated engines (in the previous versions stabilization was done by directing exhaust from the main engines). The engine control system was also reworked, increasing the number of sensors from 700 to 13,000.
• November 23, 1972 – Vehicle serial number 7L – regular Soyuz 7K-LOK (Soyuz 7K-LOK No.1) and dummy LK module-spacecrafts for Moon flyby – the engines ran for 106.93 seconds after which pogo oscillation of the first stage caused engine cutoff (a problem which also plagued the engineers of the US Saturn V) at 40 km altitude; a programmed shutdown of some of the engines to prevent over-stressing of the structure led to an explosion of the oxygen pump on engine number 4. The vehicle disintegrated.
• Fifth launch of modified N1 serial number 8L was prepared for August 1974 with regular 7K-LOK Soyuz 7K-LOK and regular LK module-spacecrafts of L3 lunar expedition complex for Moon flyby and landing by full unmanned mission of future manned scenario but the N1-L3 program was cancelled in May 1974.