Characteristic velocity

Characteristic velocity or $c^*$ 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.

Formula

$c^* = \frac{p_1 \times A_t}{\dot{m}}$

$c^*$ is the characteristic velocity (meters/second)
$p_1$ is the chamber pressure (pascals)
$A_t$ is the area of the throat (square meters)
$\dot{m}$ is the mass flow rate of the engine (kilograms per second)

References

Rocket Propulsion Elements, 7th Edition by George P. Sutton, Oscar Biblarz