Revenge of the RP-1: RP-1 strikes back.
So as you know methane is the new hotness with its clean burning and cool FFSC. But RP-1 isn’t don’t yet!
I found this report on further optimization of kerolox engines.
Which basically states that kerolox engines can be further optimized by using the optimal combustion ratio and removal of film-cooling using lox cooling.
- The report basically says engines are using extra kerosene for regenerative cooling which means the O/F burn ratio is screwed. And then you have to pump kerosene at a certain speed so it doesn’t crack and soot up inside the cooling channels, so pumping energy loses.
- You can remove film cooling inside the engine, having a uniform mixture throughout to further increase isp. But this demands massive increase in regenerative cooling abilities. You can use oxygen for combustion chamber cooling and kerosene for nozzle skirt cooling.
So with those optimization in mind imagine a theoretical engine with rd-191m as a baseline:
Rd-191m
+ ideal mixture ratio
+ removal of film cooling
+ sub-chilled -9c RP-1 (no rocket with rd-191 use chilled RP-1) ( you can use -50c sub-chilled syntin to push even futher)
+sub-chilled lox (again no rocket with rd-191 uses sub-cooled lox)
+ potential oxygen expander cycle assist
= ideal rp-1 engine
In the report, it says using these optimization they can theoretically push engines like RD-0124 from 359 to 379 seconds isp! One one second off vacuum raptor 3!
So imagine a starship like configuration with RP-1 as propellant.
Its engine performance is only 1%-10% worse in all aspects but you basically cut the fuel tank size by half with reduced insulation.