09. What is the propellant? (A K2S Question)
From The Space Library
The propellant for the first stage of the Saturn V, and many other launch vehicles, was liquid oxygen (LOX) and RP1, a special grade of kerosene. Energy is measured in joules. One joule is equal to one Watt for one second. Imagine a one Watt light bulb being lit for one second. Kinetic energy is the energy of motion and is also measured in joules, equal to half the mass multiplied by the velocity squared. For example, one joule is the energy in a two kilogram mass moving at one meter per second. Imagine a two kilogram hammer swung at one meter per second. Mega-joule is a million joules. This LOX/RP1 mixture has a specific energy of 4.5 mega-joules per kilogram, which can achieve an exhaust velocity of about 6,700 miles per hour. The solid rocket motors on the Space Shuttle have a similar performance with a propellant composed of a rubber-like fuel, with some powdered aluminum in it, mixed with ammonium perchlorate as the oxidizer. The upper stages of the Saturn V and the Space Shuttle main engines utilize LOX and liquid hydrogen as propellant. This combination has a specific energy of about ten mega-joules per kilogram (2.2 pounds) and can achieve an exhaust velocity of about 14,764 feet per second.
Answer provided by John W. Cole
Question and Answer extracted from the book Kids to Space - by Lonnie Schorer
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