Encyclopedia Astronautica
1969.07.03 - N1 5L launch

N-1 serial number 5L began to fail at 0.25 second after liftoff when the oxidizer pump of engine number 8 ingested a slag fragment and exploded. A fire ensued as the vehicle climbed past the top of the tower. Engines were shutdown until the acceleration dropped below 1 G; then the vehicle began to fall back to the pad at a 45 degree angle. The escape tower fired at the top of the brief trajectory, taking the L1S dummy descent module away from the pad. Upon impact of the base of the N1 with the pad, the vehicle exploded, destroying launch pad 110 east, which would take over 18 months to repair. This was the end of a slight Soviet hope of upstaging the US Apollo 11.

N1 5L had barely lifted off when peripheral engine number 8 shut down at 0.25 seconds into the flight. The booster had climbed to 200 m at T+12 seconds, when all engines shut down except number 18. The booster began to fall back, except the thrust of engine 18 tipped it from the vertical. At T+15 seconds the SAS abort tower fired, pulling the upper shroud and re-entry capsule off into the darkness. At T+23 seconds the base of the N1 hit the launch pad, and 2500 tonnes of liquid oxygen and kerosene exploded, illuminating the steppe for dozens of kilometres. At Leninsk, 35 km away, an enormous bright light burst in the north, and the residents knew the unthinkable had happened. All of the windows were blown out of the apartment buildings at area 113, and at the back-up N1 launch complex 6 km away. Everyone was ordered out of the bunker except Afanasyev, Dorofeyev, Kirillov, and Moiseyev. 'It rained kerosene' one witness said. 'At least no one was hurt,' said another. 'Not true,' intoned Barmin, 'we who built this launch complex will have to rebuild it'. He demanded an investigative commission to fix the blame for the catastrophe.

The cost was not so much in roubles as in the years of time it would take to rebuild. But the left N1 launch pad was intact and available for further launches. Further preparations for N1 launches were cancelled until the disaster investigative commission had completed its report. Barmin stated flatly he would never again allow one of his pads to be used for launch of a rocket that was capable of shutting down its engines. It must be designed to crash away from the launch pad.

Kuznetsov was pushed from the first moments after the launch to accept responsibility based on the hypothesis of a foreign object in a turobpump. The KORD had commanded shutdowns of engines 7, 19, 20, and 21 - but telemetry indicated this did not occur. Number 18 had chaotic performance parameters before it shut down. In that engine's lox pump's steel diaphragm a sensor spiked with incredible force. Kuznetsov blamed this pump as the source or another 'external object'. Mishin believed the failure was due to a defective pump rotor, which disintegrated at start-up. However Mishin couldn't state his position publicly -- after all, he had defended use of Kuznetsov's engines to a state commission at the end of 1967. So Kuznetsov, his engineers, and the military inspectors all blamed a 'foreign object'.

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