I've been learning about rocket propulsion and had an idea for an engine cycle, maybe its been done before but I haven't been able to find anything this online. So the full flow staged combustion cycle has many benefits over other cycles such as:

  • smaller, lower power turbopumps needed
  • no need for the fuel/oxidizer seal that can cause engine failure

My idea is to do a hybrid between staged combustion and FFSC. By this I mean having two preburners to get the benefits of FFSC, but running them both fuel rich for simplicity. So it would essentially be a fuel rich staged combustion cycle, but with two separate preburners/turbopumps to eliminate the shaft seal, lighter weight, etc. Good idea / bad idea?

  • $\begingroup$ If your LOX turbopump turbine is driven by fuel-rich gas, you'll need a good shaft seal. $\endgroup$
    – user8269
    Apr 5, 2018 at 1:47

1 Answer 1


You are describing the SSME. It is (was) a staged combustion engine with two fuel-rich preburners.

enter image description here

Your concept may differ, of course, but your question is not detailed enough to determine that.


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