Liquid‐Fueled Rockets

Abstract Since the beginning of the space age, liquid‐fueled rockets have provided the basis of everything we have accomplished in space. Whether it has been the mighty F‐1, which powered Apollo to the Moon, or the workhorse RL‐10, or the high performance SSME, all of the major missions depend on liquid‐fueled propulsion. And as we move forward to the next generation systems, the success or failure of these systems will be intimately tied to the success of its liquid‐fuel propulsion system. The following discussion focuses on the design of liquid‐fueled rocket systems and examines the design choices that must be considered in integrating the propulsion system for a selected application. It is to be understood that liquid‐fueled systems refer to the oxidizer as well as the fuel and that both of these are carried aboard the vehicle. Today's liquid‐fueled rocket propulsion designs originate from the theories of a Russian, Konstain E. Tsiolkovsky, and from experiments performed by an American, Robert H. Goddard and a German, Herman Oberth. Goddard and Oberth made some of the first working liquid propellant rocket engines. A liquid‐fueled rocket propulsion system consists of a number of carefully integrated components that must be chosen and designed to function as part of the whole. The operation of an integrated system can best be viewed by identifying the required functions that must be satisfied and then considering the components that are chosen to fulfill these functions. The primary function of a rocket propulsion system is to produce thrust that accelerates the spacecraft to the final velocity required to achieve its goal. To produce a practical propulsion system, the integrated system must control the flow of propellants from the storage tanks, deliver them at the required pressures, and inject them into the combustor. Part of this article is structured around the subsystems of an engine. But it is important to keep in mind that these engines are highly coupled systems, from both the viewpoint of mechanical systems and fluid flow. An overview of some of the design issues are given to put things in perspective.