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lecture7_new - 16.522, Space Propulsion Prof. Manuel...

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16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 1 of 12 16.522, Space Propulsion Prof. Manuel Martinez-Sanchez Lecture 7: Bipropellant Chemical Thrusters and Chemical Propulsion Systems Considerations (Valving, tanks, etc) Characteristics of some monopropellants (Reprinted from H. Koelle, Handbook of Astronautical Engineering , McGraw-Hill, 1961.) Flame Chemical Density temp, F D C * ,fps I sp ,S Sensitivity Nitromethane 1.13 4002 5026 244 Yes Nitroglycerine 1.60 5496 4942 244 Yes Ethyl nitrate 1.10 3039 4659 224 Yes Hydrazine 1.01 2050 3952 230 No Tetronitromethane 1.65 3446 3702 180 Yes Hydrogen peroxide 1.45 1839 3418 165 No Ethylene oxide 0.87 1760 3980 189 No n-Propyl nitrate 1.06 2587 4265 201 Yes
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16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 2 of 12
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16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 3 of 12 Thruster Weight A least-square curve fit of the weight of nine different thruster/valve designs with thrust levels from 1 to 150 lb produces the following relation: 0.55235 = 0.34567 t WF The figure above shows the correlation; the correlation coefficient is 0.97. For low thrust levels, the thruster weight approaches the valve weight, an effect that Equation (4.5) will not predict. Use 0.4lb as a minimum thruster/valve weight for low thrust levels. Note that figure above is for a thruster with single valves.
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16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 4 of 12 1) Capillary devices , which use surface tension forces to keep gas and liquid separated. These are particularly useful for bipropellant systems like the space Shuttle and Viking Orbiter because they are compatible with strong oxidizers. 2) Diaphragms and bladders , which are physical separation devices made of elastomer or Teflon. These are used by Voyager, Mariner 71, and Magellan. Elastomer types are not compatible with oxidizers.
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lecture7_new - 16.522, Space Propulsion Prof. Manuel...

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