Characteristic velocity, denoted c ∗ {\displaystyle c^{*}} (pronounced c-star), is a measure of the combustion performance of a rocket engine independent of nozzle performance, and is used to compare different propellants and propulsion systems. It is independent of the nozzle, making it a useful metric for evaluating propellant combustion alone. c* should not be confused with c, which is the effective exhaust velocity related to the specific impulse by: I s p = c g 0 {\displaystyle I_{sp}={\frac {c}{g_{0}}}} . Specific impulse and effective exhaust velocity are dependent on the nozzle design unlike the characteristic velocity, explaining why C-star is an important value when comparing different propulsion system efficiencies. c* can be useful when comparing actual combustion performance to theoretical performance in order to determine how completely chemical energy release occurred, or the combustion efficiency. This is known as c*-efficiency, or n v {\displaystyle n_{v}} , and is calculated by dividing c A c t u a l ∗ {\displaystyle c_{Actual}^{*}} with c T h e o r e t i c a l ∗ {\displaystyle c_{Theoretical}^{*}} . Standard values for n v {\displaystyle n_{v}} range from 0.85 to 1.03.
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This article is an automated import of the Wikipedia article "Characteristic velocity", available at https://en.wikipedia.org/wiki/Characteristic_velocity . Text is licensed under CC BY-SA 4.0.