ROCKET PROPULSION — COOPER 



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LIQUID PROPELLANT ROCKETS 



In order to achieve higher exhaust velocities, it is necessary to use 

 propellants with combustion products of low molecular weight, and 

 these chemicals are generally liquid or gaseous at room temperatures. 

 The gases (such as oxygen) would require too much volume and 

 weight to be contained in that state, and thus are liquefied and kept 

 at low (cryogenic) temperatures, in contrast to so-called "storable" 

 propellants which are liquid at room temperatui-es. The first liquid 

 propellant rocket engine was made about 1900, and in the 1920's and 

 1930's work on them was carried out independently in Germany and 

 in the United States. Little was done in this country except the work 

 of Prof. Robert Goddard. 



A variety of applications and propellant combinations were evolved, 

 including an antiaircraft missile using aniline as the fuel and nitric 

 acid as the oxidizer, aircraft rocket engines utilizing alcohol and con- 

 centrated hydrogen peroxide, and finally the V-2, an alcohol and liquid 

 oxygen missile. Based on research of the 1930's, its design was begun 

 in 1938, and the first experimental flight was in 1942. Fortunately, 

 internal political squabbles prevented its completion until late in the 

 war. A 3,000-mile range, two-stage missile was being designed for 

 bombarding the American Continent. 



With the V-2, rocketry came of age. The Redstone missiles which 

 were used for the U.S. suborbital manned flights were basically scaled- 

 up versions of the V-2, as were early postwar Russian rockets. Long- 

 range rockets with high explosive warheads are poor, expensive, 

 inaccurate weapons, and probably would not have been developed 

 except for the appearance of nuclear weapons, which gave the final 

 impetus that led rapidly to space exploration capability. 



The variety of propellant combinations and types of liquid rocket 

 engmes rapidly multiplied, and so a brief discussion must select and 

 over-simplify. The propulsion system includes tankage, propellants, 

 pumps to bring propellants to the combustion chamber where they 



combustion chamber 

 cooling jacket injector 



tanks (reduced) 



Figure 2. — Simplified scliematic of a typical liquid propellant rocket. 



