What were key factors that made the N1 the recipe for disaster it became for the USSR? Especially when the USSR was the Space King at the time?
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9$\begingroup$ Stopping development halfway through is never a good idea. $\endgroup$– SE - stop firing the good guysCommented Apr 6, 2016 at 14:56
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3$\begingroup$ Each aspect of this question could be answered separately, and would allow a better coverage of the topic overall. It is also helpful to know what you are already aware of from your own research, especially if you provide links. That way the answers don't cover stuff you already know, but visitors less familiar with the topic can fill in what they don't know using both the question and its answers. $\endgroup$– kim holderCommented Apr 6, 2016 at 15:17
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3$\begingroup$ I agree with @kimholder. Also, I wouldn't just assert the SU was ever "Space King". $\endgroup$– Rikki-Tikki-TaviCommented Apr 6, 2016 at 15:20
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2$\begingroup$ At an early stage of the program, it was estimated test 15 launches would be needed to fully flight-qualify the N1. At that time, this was not seen as a problem. The loss of flight 1-4 was not unexpected. The program ended because the space race was lost, and due to lack of political will to continue. $\endgroup$– HobbesCommented Apr 6, 2016 at 16:33
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2$\begingroup$ The old chestnut about 30 engines has already come up here. May I point out that Falcon Heavy has 27 engines and will likely be a big success. Large number of engines is not necessarily a cause of failure. Lack of development and trying to control so many engines with 60's technology might be. Soyuz solved the problem of not being able to make huge combustion chambers/nozzles in a different way: it has 5 engines, each with 4 combustion chambers/nozzles for a total of 20. $\endgroup$– Level River StCommented Apr 7, 2016 at 10:31
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2 Answers
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Generically the program was underfunded, and the main issue was lack of full up testing of each stage.
With 30 engines, the interactions in the plumbing were very complex and caused imperfect fuel/oxidizer flow that affected the engines.
Engines that were sensitive to fuel/oxidizer flow issues with lots of them, lots of plumbing, huge volumes, needs lots of testing to get just right.
It is possible that quality control to achieve whatever solution was needed might have been beyond the Soviets. (Imagine rough welds inside pipes, and issues that might cause in this context. Then imagine the thousands of welds it likely needed).
With more time and money, they likely would have gotten much closer or even succeeded. Hard to know. But without the testing, failure was almost certainly guaranteed without great amounts of dumb luck.
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2$\begingroup$ Apparently a first stage test stand was ruled out because it would tie up too much of the available concrete production at the time. $\endgroup$– HobbesCommented Apr 6, 2016 at 16:35
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1$\begingroup$ @Hobbes Now THAT is interesting! Such low tech as Concrete production, limits access to the moon. Neato completo! $\endgroup$– geoffcCommented Apr 6, 2016 at 16:57
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5$\begingroup$ @Hobbes Any chance of a source on this? I'd love to read more! $\endgroup$ Commented Apr 6, 2016 at 17:39
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$\begingroup$ @Hobbes: Bizarre. They could have just filled the upper stage housing with earth for much the same effect. $\endgroup$– JoshuaCommented Apr 7, 2016 at 15:39
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1$\begingroup$ I think I'll have to retract this, haven't found a reference anywhere. According to Chertok's 'Rockets and people', they estimated the first stage test stand would cost R100 million and would take four years to build. Korolev was adamant not to allow this delay, over objections from e.g. Leonov. "Khrushchev does not agree and says that the government would never have denied Korolev proper ground-testing facilities had he asked for them - 'especially a chief designer of Korolev's calibre" (from 'Soviet and Russian lunar exploration') $\endgroup$– HobbesCommented Apr 8, 2016 at 9:15
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To add to geoffc's excellent answer, another issue that might have been worked out with more testing was the KORD, a computer system for controlling the 30 different engines. Ideally, the KORD would handle the failure of one engine by stopping the engine on the opposite side of the rocket, maintaining symmetry of thrust. However, during the first and second test flights, the KORD ended up shutting down all the engines after detecting a failure of one engine. The second failure happened just a few seconds after liftoff; the rocket fell back to the pad and exploded, destroying the main pad and forcing the Soviets to spend a year and a half rebuilding.
More generally, a lot of the N1's problems stem from trying to eke an extra 20 tons out of it. The 7K-LOK/LK lunar spacecraft ended up substantially overweight, requiring the N1 to lift 95 metric tons instead of 75. This forced the designers to add 6 extra engines, which can't have helped things (although 24 engines was already pushing it). The N1 (and the Soviet program in general) also suffered from a lack of commitment and leadership, especially after Korolev's death in 1966.
Sources/further reading:
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15$\begingroup$ "Yeah, we know we told you to design for 75 tons, but now we need 95 tons. You can fix that in software, right?" $\endgroup$ Commented Apr 6, 2016 at 18:50
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3$\begingroup$ "Well, our agile burndown chart indicates we will either have to seriously sacrifice quality, or seriously sacrifice deadlines." -- Look son, we don't call this whole thing a space race for no reason. $\endgroup$– vgruCommented Apr 7, 2016 at 7:47
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1$\begingroup$ I thought Agile was invented a decade later. I recall that aerospace used the Waterfall model prior to the 777 team, according to the Nova episode. $\endgroup$– JDługoszCommented Apr 7, 2016 at 8:13
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1$\begingroup$ The early US space program certainly used waterfall. No idea about USSR. But I believe this was intended as a jest. $\endgroup$ Commented Apr 7, 2016 at 12:31
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1$\begingroup$ @DylanSp And the 75 tonne version of the N1 could be used to launch the Soyuz 7K-LOK, correct? $\endgroup$ Commented Apr 7, 2016 at 12:48