proptools.solid module

Solid rocket motor equations.

chamber_pressure(K, a, n, rho_solid, c_star) Chamber pressure due to solid propellant combustion.
burn_area_ratio(p_c, a, n, rho_solid, c_star) Get the burn area ratio, given chamber pressure and propellant properties.
burn_and_throat_area(F, p_c, p_e, a, n, …) Given thrust and chamber pressure, and propellant properties, find the burn area and throat area.
thrust_curve(A_b, x, A_t, A_e, p_a, a, n, …) Thrust vs time curve for a solid rocket motor.
proptools.solid.burn_and_throat_area(F, p_c, p_e, a, n, rho_solid, c_star, gamma)

Given thrust and chamber pressure, and propellant properties, find the burn area and throat area.

Assumes that the exit pressure is matched (\(p_e = p_a\)).

Parameters:
  • F (scalar) – Thrust force [units: newton].
  • p_c (scalar) – Chamber pressure [units: pascal].
  • p_e (scalar) – Nozzle exit pressure [units: pascal].
  • a (scalar) – Propellant burn rate coefficient [units: meter second**-1 pascal**-n].
  • n (scalar) – Propellant burn rate exponent [units: none].
  • rho_solid (scalar) – Solid propellant density [units: kilogram meter**-3].
  • c_star (scalar) – Propellant combustion characteristic velocity [units: meter second**-1].
  • gamma (scalar) – Exhaust gas ratio of specific heats [units: dimensionless].
Returns:

tuple containing:

A_b (scalar): Burn area [units: meter**2].

A_t (scalar): Throat area [units: meter**2].
Return type:

tuple
proptools.solid.burn_area_ratio(p_c, a, n, rho_solid, c_star)

Get the burn area ratio, given chamber pressure and propellant properties.

Reference: Equation 12-6 in Rocket Propulsion Elements, 8th edition.

Parameters:
  • p_c (scalar) – Chamber pressure [units: pascal].
  • a (scalar) – Propellant burn rate coefficient [units: meter second**-1 pascal**-n].
  • n (scalar) – Propellant burn rate exponent [units: none].
  • rho_solid (scalar) – Solid propellant density [units: kilogram meter**-3].
  • c_star (scalar) – Propellant combustion characteristic velocity [units: meter second**-1].
Returns:

Ratio of burning area to throat area, \(K = A_b/A_t\) [units: dimensionless].
Return type:

scalar
proptools.solid.chamber_pressure(K, a, n, rho_solid, c_star)

Chamber pressure due to solid propellant combustion.

Reference: Equation 12-6 in Rocket Propulsion Elements, 8th edition.

Parameters:
  • K (scalar) – Ratio of burning area to throat area, \(A_b/A_t\) [units: dimensionless].
  • a (scalar) – Propellant burn rate coefficient [units: meter second**-1 pascal**-n].
  • n (scalar) – Propellant burn rate exponent [units: dimensionless].
  • rho_solid (scalar) – Solid propellant density [units: kilogram meter**-3].
  • c_star (scalar) – Propellant combustion characteristic velocity [units: meter second**-1].
Returns:

Chamber pressure [units: pascal].
Return type:

scalar
proptools.solid.thrust_curve(A_b, x, A_t, A_e, p_a, a, n, rho_solid, c_star, gamma)

Thrust vs time curve for a solid rocket motor.

Given information about the evolution of the burning surface of the propellant grain, this function predicts the time-varying thrust of a solid rocket motor.

The evolution of the burning surface is described by two lists, A_b and x. Each element in the lists describes a step in the (discretized) evolution of the burning surface. x[i] is the distance which the flame front must progress (normal to the burning surface) to reach step i. A_b[i] is the burn area at step i.

Parameters:
  • A_b (list) – Burn area at each step [units: meter**-2].
  • x (list) – flame front progress distance at each step [units: meter].
  • A_t (scalar) – Nozzle throat area [units: meter**2].
  • A_e (scalar) – Nozzle exit area [units: meter**2].
  • p_a (scalar) – Ambient pressure during motor firing [units: pascal].
  • a (scalar) – Propellant burn rate coefficient [units: meter second**-1 pascal**-n].
  • n (scalar) – Propellant burn rate exponent [units: none].
  • rho_solid (scalar) – Solid propellant density [units: kilogram meter**-3].
  • c_star (scalar) – Propellant combustion characteristic velocity [units: meter second**-1].
  • gamma (scalar) – Exhaust gas ratio of specific heats [units: dimensionless].
Returns:

tuple containing:

t (list): time at each step [units: second].

p_c (list): Chamber pressure at each step [units: pascal].

F (list): Thrust at each step [units: newton].
Return type:

tuple