4 ms·
This line of thought is very reasonable for normal engines, but I wonder if it’s not quite right for the raptor. I’m not 100% on this, but I think the raptor a
by xcskier56 6y ago
This line of thought is very reasonable for normal engines, but I wonder if it’s not quite right for the raptor.
I’m not 100% on this, but I think the raptor actually runs really oxygen rich. According to Elon’s tweet and Wikipedia, it runs 3.5-1 O2-CH4. It runs so lean that the unburnt o2 cools things.
If it were running closer to 1-1 (low ch4) then it would run much hotter and burn things like we saw.
Edit: reading more I’m not positive they run O2 rich anymore
- kortex 6y agoMinor correction: 4.0 lox/methane is stoichiometric. 3.8 is rich. 3.55 is very rich. It runs fuel rich to keep cool and possibly increase specific impulse.
- tdy721 6y agoYou were probably thinking for the turbo pump? There is a lox rich condition somewhere to get full flow. Just not the overall ratio
- dotancohen 6y agoTo clarify this point. The Raptor uses two turbopumps. One turbopump hangs off the side and runs fuel rich, and this fuel-rich exhaust is the fuel input for the combustion chamber. The second turbopump, to which tdy721 is referring, sits right above the injectors and runs oxygen rich. This oxygen rich exhaust is the oxidizer input for the combustion chamber.