# SolidMotor Class#

Class to specify characteristics and useful operations for solid motors.

- Geometrical attributes

- Motor.nozzleRadius#
Radius of motor nozzle outlet in meters.

- Type:
float

- Motor.throatRadius#
Radius of motor nozzle throat in meters.

- Type:
float

- Motor.grainNumber#
Number of solid grains.

- Type:
int

- Motor.grainSeparation#
Distance between two grains in meters.

- Type:
float

- Motor.grainDensity#
Density of each grain in kg/meters cubed.

- Type:
float

- Motor.grainOuterRadius#
Outer radius of each grain in meters.

- Type:
float

- Motor.grainInitialInnerRadius#
Initial inner radius of each grain in meters.

- Type:
float

- Motor.grainInitialHeight#
Initial height of each grain in meters.

- Type:
float

- Motor.grainInitialVolume#
Initial volume of each grain in meters cubed.

- Type:
float

- Mass and moment of inertia attributes

- Motor.grainInitialMass#
Initial mass of each grain in kg.

- Type:
float

- Motor.propellantInitialMass#
Total propellant initial mass in kg.

- Type:
float

- Motor.massDot#
Time derivative of propellant total mass in kg/s as a function of time.

- Type:

- Motor.inertiaI#
Propellant moment of inertia in kg*meter^2 with respect to axis perpendicular to axis of cylindrical symmetry of each grain, given as a function of time.

- Type:

- Motor.inertiaIDot#
Time derivative of inertiaI given in kg*meter^2/s as a function of time.

- Type:

- Motor.inertiaZ#
Propellant moment of inertia in kg*meter^2 with respect to axis of cylindrical symmetry of each grain, given as a function of time.

- Type:

- Motor.inertiaDot#
Time derivative of inertiaZ given in kg*meter^2/s as a function of time.

- Type:

- Thrust and burn attributes

- Motor.totalImpulse#
Total impulse of the thrust curve in N*s.

- Type:
float

- Motor.maxThrust#
Maximum thrust value of the given thrust curve, in N.

- Type:
float

- Motor.maxThrustTime#
Time, in seconds, in which the maximum thrust value is achieved.

- Type:
float

- Motor.averageThrust#
Average thrust of the motor, given in N.

- Type:
float

- Motor.burnOutTime#
Total motor burn out time, in seconds. Must include delay time when the motor takes time to ignite. Also seen as time to end thrust curve.

- Type:
float

- Motor.exhaustVelocity#
Propulsion gases exhaust velocity, assumed constant, in m/s.

- Type:
float

- Motor.burnArea#
Total burn area considering all grains, made out of inner cylindrical burn area and grain top and bottom faces. Expressed in meters squared as a function of time.

- Type:

- Motor.Kn#
Motor Kn as a function of time. Defined as burnArea divided by nozzle throat cross sectional area. Has no units.

- Type:

- Motor.interpolate#
Method of interpolation used in case thrust curve is given by data set in .csv or .eng, or as an array. Options are ‘spline’ ‘akima’ and ‘linear’. Default is “linear”.

- Type:
string