Encyclopedia Astronautica
1965.01.01 - N1 development issues

There were two camps on the N1-L3 control systems. One group was within OKB-1, and had developed the systems for the Vostok and Zenit spacecraft, under the personal oversight of Korolev. They stressed the maximum quality and reliability in their systems. The second group had worked with Pilyugin, and had designed the systems for the Mars, Venus, Luna E-6 probes, the R-9, RT-1, RT-2, and GR-1 missiles; and piloted spacecraft. Their design emphasis was on maximum usability and output. Pilyugin had been named chief designer of the control system for the N1-L3.

There were many factors that had to be modelled - gas dynamics of 30 engines firing simultaneously, propellant behaviour in enormous spherical tanks, etc. To accomplish this OKB-1 received its first digital computers. At Finogeyev's section at NIIAP the first N1 iron bird was constructed. This test stand included all of the N1's control systems and cables. At OKB-1 Chertok was responsible for design of the engine controllers for the throttleable Kuznetsov engines and the spacecraft control systems. Iosifyian was charged with development of the electrical system, including how to provide the 5 kW worth of power the booster would use during ascent. He decided to develop the APR turbogenerator, powered by a Lyulka turbine, instead of using batteries.

A key issue was how to achieve the necessary reliability in the 36 (later 42) engines that would fire during ascent. Pilyugin was theoretically responsible for this, but he simply said: 'the engines aren't mine. In an abort due to the engines, I will not be answerable. You can shut down ten good engines and guide your rocket up your ass.' Korolev simply told Chertok, 'if you can't get Pilyugin to solve it, you'll simply have to do it yourself'. The solution - the KORD engine control system - originated in work done in 1960 after a string of rocket failures. The system was fed critical engine parameters. When the parameters on a particular engine went out of the allowable range, KORD was designed to shut down the faulty engine, and the opposing engine (in order to maintain symmetry of thrust). Separate control systems were developed for the Block G, D, E, and I stages. These included engine burn control for lunar orbit insertion, the lunar braking manoeuvre, the soft landing, ascent to lunar orbit, and re-entry. Raushenbakh modelled the scheme after the basic approaches were worked out on paper. Legostayev and Khitrikon developed the optical systems. The argument over which of two docking systems to use, Kontakt or Igla, went on for several years and held up basic planning. There was also controversy over the electrical power system - to use an 'open' variant of power distribution by fuel elements or simpler electrochemical generators. The first system was advocated by Lidorenko at VNIIT, while OKB -1 proposed the APO Lox/LH2 fuel cells. Nuclear radio thermal generators (RTG's) were another alternative.

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