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Questions tagged [j-2]

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1
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2answers
665 views

J-2 rocket nozzle length

The total length of the J-2 rocket engine is 133 inches, but what is its nozzle length from throat to exit?
4
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1answer
277 views

Was a large-nozzle variant of the J-2 ever considered?

The J-2 engine used on the upper stages of the Saturn launchers has a specific impulse in vacuum of 421 seconds. This is substantially lower than that of the smaller RL10, 440-460 seconds depending on ...
3
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0answers
577 views

If the J-2X is too powerful for SLS, why was it appropriate for Saturn V?

Reading an article about new engines for the SLS (Summary: There is no plan what to do once the current SSME's are expended), they mention that the J-2X is too powerful for the upper stage of SLS. ...
6
votes
2answers
309 views

Was the notion of using an air-started SSME on Ares-1 a reasonable idea?

For whatever reasons, it seems like the standard upper stage engine in the U.S. inventory is the RL-10. A high performance engine with nice specific impulse (Isp = 450-465 s), but very low thrust (25 ...
12
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2answers
3k views

Why the huge thrust difference between a Sea level and Vacuum J-2 engine?

Looking at the Wikipedia page for the J-2 (one engine was used on the Saturn V third stage, and 5 engines on the second stage) it gets about 232Klbs thrust in vacuum, but at sea level, only 109KLbs ...