One major advantage that SR2 has over stock SR and KSP is its costumizability, but that unfortunately gave in at the rocket engines. So I have the idea of...
ADVANCED CUSTUMIZABLE ROCKET ENGINES!
These engines will have the following costumizable attributes:
Fuel type: RP-1, Hydrogen (please add hydrogen), and Monopropellant. (Monopropellant engines have a size and thrust limit and only one engine cycle-pressure fed)
Size: ONLY affects the combustion chamber size, which determines the base thrust. Also determines base mass and cost.
Engine cycle: Determines the efficiency (changes thrust based on base thrust) and additional mass and cost of the engine. Available cycles are:
- Gas generator cycle (low effeciency, mass and cost)
- Staged combustion cycle (High effeciency, mass, cost)
- Combustion tap off cycle (Medium effeciency, mass, cost)
- Electric pump cycle (high effeciency, low mass and cost, requires a lot of power to run, limited to low thrust)
- Expander cycle (High effeciency, medium mass and low cost, limited to low thrust and hydrogen fuel)
- Pressure fed cycle (high effeciency, low mass and cost, limited to VERY low thrust, only engine cycle available for Monopropellant engines)
Expansion ratio: Affects nozzle size and thus engine effeciency in different parts of the atmosphere (probably will only have a high, medium, and low choice for simplicity). Also affects additional mass and cost