FIGURE 3.1 Highly simplified schematic of a closed-cycle, staged-combustion rocket engine. Because the preburner, turbine, and thrust chamber operate in series, the required pump pressure is higher compared to open-cycle engines. SOURCE: Air Force Research Laboratory.
There are several conventional options for vehicle thrust vector control; these would combine one or more thrust chambers with some type of non-toxic propellant reaction control subsystem, which will likely be required at a minimum to achieve roll control, but these will not be discussed here in detail.
Engine throttling, which is usually required together with control of the mixture ratio, is accomplished with a complex combination of flow bypass valves, throttle valves, and fixed bias and calibration orifices that are inserted during engine and hydraulics system build-up, calibration, and hot fire tests. All liquid RP-1 enters the thrust chamber cooling jacket prior to entering the MCC injectors and is mixed with the oxidizer-rich preburner exhaust gases to achieve the final main chamber combustion process. The liquid cooling jacket (heat exchanger), together with some film cooling of the MCC chamber wall, maintains the MCC at an acceptable operating temperature while allowing the necessary engine combustion efficiency and associated Isp.
In considering the hydrocarbon-fueled ORSC rocket engine that will serve at the MPS for the reusable booster, the committee identified 12 risk areas: