# Characteristic Velocity

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Characteristic velocity, abbreviated as U, measure the effectiveness of the combustion of a rocket engine at high temperature and pressure, seperate from nozzle performance.  It is used to compare different propellant and propulsion systems.

## Characteristic velocity formula

 $$\large{ U = \frac { p_c \; A } { \dot m_f } }$$

### Where:

 Units English Metric $$\large{ U }$$ = characteristic velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$\large{ A }$$  (Greek symbol rho) = area of throat $$\large{ft^2}$$ $$\large{m^2}$$ $$\large{ \dot m_f }$$ = mass flow rate $$\large{\frac{lbm}{sec}}$$ $$\large{\frac{kg}{s}}$$ $$\large{ p_c }$$ =  pressure of chamber $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$

## Related Characteristic Velocity formulas

 $$\large{ U = \sqrt{ 2 \; Ec \; c \; \Delta T } }$$ (Eckert number) $$\large{ U = \sqrt{ \frac{\Delta p}{Eu \; \rho} } }$$ (Euler number)

### Where:

$$\large{ U }$$ = characteristic velocity

$$\large{ \rho }$$  (Greek symbol rho) = density

$$\large{ Ec }$$ = Eckert number

$$\large{ Eu }$$ = Euler number

$$\large{ c }$$ = specific heat

$$\large{ \Delta T }$$ = temperature change Tags: Velocity Equations