THE ENGINES THAT
CAME IN FROM THE COLD

The Engines That Came In From The Cold told the amazing story behind the use of Russian-designed rocket engines in the next generation of US space launchers. The engines harness a technology that Americans thought to be beyond the capabilities of modern engineering - but which had in fact been mastered by the Russians 30 years ago.

Russia’s lead in rocket technology came largely thanks to the work of one man - Sergei Korolev, Russia’s most senior rocket scientist. His approach to rocket design was to ‘try it and see’, using test flights to answer important design questions. Failures were common, but Korolev’s team always learned something from them.

Their greatest challenge in the 1960s was to beat the Americans in the race to land humans on the Moon. The launcher would be a giant new rocket, the N-1. But there were no engines powerful enough to do the job. Korolev’s solution was to commission a radical new design of rocket engine - not from any of Russia’s foremost engine designers, but from Nikolai Kuznetsov, the designer of the jet engines used for long-range Soviet bombers. The solution they came up with was to use lots of small engines rather than a single large one.

The challenge was to create a powerful, compact and efficient liquid-fuelled rocket engine. To do it, Kuznetsov and his team would have to crack a problem that had always been avoided as too difficult and dangerous. Instead of the normal procedure of venting the exhaust gases from the pre-burners that powered the fuel compressors, they would have to find a way of channelling them into the main chamber as part of the combustion mixture.

If it could be done, it would boost the lifting power of the engine by 25 percent. What they came up with was the compact NK-15, which was both original and elegant.

But before Kuznetsov’s engines could be tested in action on the N-1, Korolev died. It was only three years later, in February 1969, that the N-1/NK-15 combination finally had its first test flight. It ended in failure when the rocket exploded 40 kilometres from the launch site. The second test also failed, when the N-1 blew up on the launchpad. Seventeen days later America succeeded in putting the first men onto the surface of the Moon. The Russians had lost their lead in the space race.

Despite this setback, Kuznetsov and his team continued to improve the engines, producing a reliable and more powerful version called the NK-33. However, before the new engines could be tried out in a test launch, the N-1 project was cancelled by the Soviet Politburo. Orders came to destroy all traces of the N-1 programme. But Kuznetsov secretly stored all the NK-33 engines, which vanished without trace until the end of the Cold War. Then a team of rocket scientists from the US began to hear rumours of rocket engines for sale....

Ten years on, the technology unlocked from Kuznetsov’s secret store of engines is at the heart of the powerhouse for the next generation of US space rockets.

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