Space Power
RESEARCH I/II LARRY PECAN FINAL REPORT 9-27-98 INTRODUCTION The following is a research project on Space Vehicle Propulsion. It shall consist of four sections, each discussing specific topics. Section One lays out the basic ideas of rocketry. Section Two compares Rocket Propulsion Systems, and shows the basis for the comparison. It also shows how each specific Rocket System works and Section Three gives a description of how Space Propulsion has evolved and contains a conclusion. SECTION 1 The Basics Section One is a brief description of the basic properties of Rocket Systems. It defines the key terms and shows how a basic rocket works. It also shows the State if The Art. I have chosen to do my project on space vehicle propulsion. Basically, this means that my research shall be based primarily on rocketry. Rocketry is a way of propulsion that has developed in numerous ways since it was first used to propel fireworks in the 16th century. It has emerged into an extremely complicated science that few actually understand. Most space rocketry in America is used in NASA (National Aeronautics and Space Association) space projects. NASA, a government association that focuses on space exploration, is the main user
of rocket technology. It is used mostly to power their satellites and shuttles into space. Pushing an object that weighs as much as a space shuttle does directly vertical until escaping the Earth's atmosphere requires a tremendous amount of power. This is why NASA uses rockets. Rockets are essentially the most powerful forms of propulsion there is today. Space Vehicle Propulsion is based rocket engines. The basic principle of rocket engine is that when fuel is burned in the engine, the reaction mass is expelled at high speeds. As a result of Newton's law of action and reaction this pushes the vehicle in the opposite direction of the one in which the reaction mass is moving. Thrust is the force that the engine exerts on all space behind it in order to "push" the vehicle forward. Efficiency is the way that the quality of rocket engines is measured by. It is measured by the time it takes for one kilogram of propellant to create one kilogram of thrust. The goal of my research is to find out what makes these engines more efficient. In rocketry, the state of the art is extremely hard to define, since there are so many different forms of rocketry ranging from liquid propellant rockets to fireworks. The state of the art though is probably nuclear powered rockets. It is much more efficient because it does not use chemical combustion like most rockets do. Instead NFRRs (Nuclear Fission Reactor Rockets) heat hydrogen in a fission reactor which expels the propellant at blistering speeds. Much research is being done with NFRRs. They are still highly experimental because of the dangers that could be associated with them. The NERVA (Nuclear Engine for Rocket Vehicle Application) was one of the most extensive NFRR research projects, however it failed because of the inability figure out an approach to putting the research into a developmental stage. SECTION 2 Specific Rocket Propulsion Systems Section One has laid the foundation for further research in the are of rocketry. Section two shall discuss properties of efficiency in more depth, it shall lay out the types of rockets in existence now. It shall also show which type of rocket is the most efficient. After this section, the next one shall describe how the reasons for these specific rockets efficiency and depending on the outcome of that report, the topic of the fourth shall be decided. EFFICIENCY Efficiency is the most important part of my research as yet. Since the object of my research is to find out which type of rockets are the most efficient and why, the reader of this paper must have a basic understanding of efficiency. Once this is established, new definitions will come into play, all of these shall be crucial in the understanding of the paper. Terms Needed To Understand Efficiency G- a unit of acceleration [equal to 9.8 meters/second/second (accelerating at a pace of 9.8 meters per second every second)] Specific Impulse (Isp)- A measurement in seconds of efficiency. Properties of Efficiency Efficiency is the most accurate indicator of rockets performance. As stated in the aforementioned definitions, specific impulse is the basic unit of measurement of rocket efficiency. Isp is found by dividing the exhaust velocity by g (definition also mentioned above). Since velocity is measured in m/s (meters per second) and each g is equal to 9.8 m/s/s (meters per second every second), the terms cancel to leave just a unit in seconds. The resulting figure, is the duration of time for which one kilogram of propellant can produce one kilogram of thrust. Thus, a higher number represents a better, and more efficient rocket. To give the reader an idea of the average Isp of several type of rockets, I have listed some average figures for efficiency of certain types of rockets below. Average Efficiencies of Certain Rockets Next, I have listed the Isp values for some basic types of rockets. After
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Approximate Word count = 2595
Approximate Pages = 10 (250 words per page double spaced)
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