Thrust and Specific Impulse for Rockets

Thrust and Specific Impulse for Rockets

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Figure 14.1: Schematic of rocket nozzle and combustion chamber

The steady flow energy equation

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then with no heat transfer or shaft work,

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which can be written as

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and manipulated to obtain

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using

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Then considering the relationship we derived for thrust,

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and assuming clip_image012, then

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and

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Rearranging,

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Thus the specific impulse can be directly related to the exhaust velocity leaving the rocket,

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