Editing N1 (rocket) (section)

===Lunar N1 development starts===
[[Valentin Glushko]], who then held a near-monopoly on rocket engine design in the Soviet Union, proposed the [[RD-270]] engine using [[unsymmetrical dimethylhydrazine]] (UDMH) and [[nitrogen tetroxide]] (N<sub>2</sub>O<sub>4</sub>) propellants to power the newly enlarged N1 design. These [[hypergolic]] propellants ignite on contact, reducing the complexity of the engine, and were widely used in Glushko's existing engines on various [[ICBM]]s. The full flow [[staged combustion cycle]] RD-270 was in testing before program cancellation, achieving a higher [[specific impulse]] than the [[gas-generator cycle]] [[Rocketdyne F-1]] despite the use of UDMH/N<sub>2</sub>O<sub>4</sub> propellants with lower potential impulse. The F-1 engine was five years into its development at the time and still experiencing combustion stability problems. [[Rocketdyne]] eventually solved the F-1 instability problems by adding copper dividers as baffles,<ref>{{cite web |last1=Anderson |first1=Colleen E. |title=A New View of the Rocketdyne F-1 Engine |url=https://airandspace.si.edu/stories/editorial/new-view-rocketdyne-f-1-engine |website=National Air and Space Museum |date=2 November 2022 |publisher=Smithsonian National Air and Space Museum |access-date=30 May 2024}}</ref> but the RD-270 still had unsolved instability problems when the N1 program was cancelled in 1974, long after the F-1 problems were solved.<ref>{{cite web |last1=Wade |first1=Mark |title=RD-270 |url=http://www.astronautix.com/r/rd-270.html |website=Astronautix |publisher=Mark Wade |access-date=30 May 2024}}</ref>

Glushko pointed out that the US [[Titan II GLV]] had successfully flown crew with similar hypergolic propellants. Korolev felt that the toxic nature of the fuels and their exhaust presented a safety risk for crewed space flight, and that kerosene/LOX was a better solution. The disagreement between Korolev and Glushko over the question of fuels ultimately became a major issue that hampered progress.<ref name="astronautix-korolev">{{Cite web |last1=Wade |first1=Mark |title=Korolev, Sergei Pavlovich |url=http://www.astronautix.com/k/korolev.html |url-status=live |archive-url=https://web.archive.org/web/20240211031622/http://www.astronautix.com/k/korolev.html |archive-date=11 February 2024 |access-date=19 January 2019 |website=astronautix }}</ref><ref name="lindroos2007">{{Cite web |editor-last=Lindroos |editor-first=Marcus |year=2007 |title=The Soviet Manned Lunar Program |url=https://ocw.mit.edu/courses/sts-471j-engineering-apollo-the-moon-project-as-a-complex-system-spring-2007/f497346756fdcce5dae17e9106e1083e_soviet_mand_lunr.pdf |url-status=live |archive-url=https://web.archive.org/web/20240223090852/https://ocw.mit.edu/courses/sts-471j-engineering-apollo-the-moon-project-as-a-complex-system-spring-2007/f497346756fdcce5dae17e9106e1083e_soviet_mand_lunr.pdf |archive-date=23 February 2024 |access-date=19 January 2019 |website=MIT OpenCourseWare |publisher=[[Massachusetts Institute of Technology]] }}</ref>

Personal issues between the two played a role, with Korolev holding Glushko responsible for his incarceration at the [[Kolyma#Emergence of the Gulag camps|Kolyma Gulag]] in the 1930s and Glushko considering Korolev to be cavalier and autocratic towards things outside his competence. The difference of opinions led to a falling out between Korolev and Glushko. In 1962, a committee was appointed to resolve the dispute and agreed with Korolev. Glushko refused outright to work on LOX/kerosene engines, and with Korolev in general. Korolev eventually gave up and decided to enlist the help of [[Nikolai Dmitriyevich Kuznetsov|Nikolai Kuznetsov]], the [[Kuznetsov Design Bureau|OKB-276]] [[jet engine]] designer, while Glushko teamed up with other rocket designers to build the very successful [[Proton (rocket family)|Proton]], [[Zenit (rocket family)|Zenit]], and later [[Energia (rocket)|Energia]] rockets.

Kuznetsov, who had limited experience in rocket design, responded with the [[NK-15]], a fairly small engine that would be delivered in several versions tuned to different altitudes. To achieve the required amount of thrust, it was proposed that 30 NK-15s would be used in a clustered configuration. An outer ring of 24 engines and an inner ring of six engines would be separated by an air gap, with airflow supplied via inlets near the top of the booster. The air would be mixed with the exhaust in order to provide some degree of [[air-augmented rocket|thrust augmentation]], as well as engine cooling. The arrangement of 30 rocket engine nozzles on the N1's first stage could have been an attempt at creating a crude version of a toroidal [[aerospike engine]] system; more conventional aerospike engines were also studied.