Questions tagged [j-2]
A liquid hydrogen/oxygen engine, used by the Saturn V's second and third stages.
6
questions
23
votes
1answer
3k views
Why is fuel ratio different for upper stage of a rocket?
After reviewing this amazing graphic posted in another question:
I noticed that the LH/LOX ratio is slightly different in the Second and Third stages. The mass stoichiometry of the reaction:
2 H2 + ...
5
votes
1answer
388 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 ...
12
votes
2answers
4k 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 ...
3
votes
2answers
518 views
Why were the SSMEs so much more fragile than the J-2 engines?
This answer mentions that the J-2 engines used by the Saturn V's second and third stages were substantially more resilient than the "extremely complex and sensitive" Space Shuttle main engines. What ...
3
votes
1answer
204 views
How would the STS have differed if it used J-2's as the main engine?
In the spirit of counterfactual rocket design questions such as this one - how would the STS have differed from its actual design if it used J-2's as the main engine? What would be the loss in payload ...
1
vote
2answers
984 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?
