ENH: Implementing 3-dof-simulation

rocketpy/motors/PointMassMotor.py

@@ -0,0 +1,74 @@
+from functools import cached_property
+import numpy as np
+from ..mathutils.function import Function, funcify_method
+from .motor import Motor
+
+class PointMassMotor(Motor):
+    """Class representing a motor modeled as a point mass.
+    Inherits from the Motor class and simplifies the model to a thrust-producing
+    object without detailed structural components."""
+
+    def __init__(
+        self,
+        thrust_source,
+        dry_mass,
+        thrust_curve=None,
+        propellant_initial_mass=None,
+        propellant_final_mass=None,
+        burn_time=None,
+        center_of_dry_mass_position=0,
+        interpolation_method="linear",
+    ):
+        """Initialize the PointMassMotor class.
+
+        Parameters
+        ----------
+        thrust_source : int, float, callable, string, array, Function
+            Thrust source similar to the Motor class.
+        dry_mass : float
+            Total dry mass of the motor in kg.
+        thrust_curve : Function, np.array, or str (csv file), optional
+            Required if thrust_source is a csv file, Function, or np.array.
+        propellant_initial_mass : float, optional
+            Required if thrust_source is a csv file, Function, or np.array.
+        propellant_final_mass : float, optional
+            Required if thrust_source is callable.
+        burn_time : float or tuple of float, optional
+            Required if thrust_source is callable or if a thrust value is given.
+        center_of_dry_mass_position : float, optional
+            Initial position of the motor, default is 0.
+        interpolation_method : string, optional
+            Interpolation method for thrust curve, default is 'linear'.
+        """
+        if isinstance(thrust_source, (Function, np.ndarray, str)):
+            if thrust_curve is None or propellant_initial_mass is None:
+                raise ValueError("thrust_curve and propellant_initial_mass are required for csv, Function, or np.array inputs.")
+        elif callable(thrust_source):
+            if any(param is None for param in [thrust_curve, propellant_initial_mass, burn_time, propellant_final_mass]):
+                raise ValueError("thrust_curve, propellant_initial_mass, burn_time, and propellant_final_mass are required for callable inputs.")
+        elif isinstance(thrust_source, (int, float)):
+            if any(param is None for param in [thrust_curve, propellant_initial_mass, burn_time]):
+                raise ValueError("thrust_curve, propellant_initial_mass, and burn_time are required when a thrust value is given.")
+
+        super().__init__(
+            thrust_source=thrust_source,
+            dry_mass=dry_mass,
+            center_of_dry_mass_position=center_of_dry_mass_position,
+            burn_time=burn_time,
+            interpolation_method=interpolation_method,
+        )
+
+    @funcify_method("Time (s)", "Thrust (N)")
+    def thrust(self):
+        """Returns the thrust of the motor as a function of time."""
+        return self.thrust_source
+
+    @cached_property
+    def total_mass(self):
+        """Returns the constant total mass of the point mass motor."""
+        return self.dry_mass
+
+    @funcify_method("Time (s)", "Acceleration (m/s^2)")
+    def acceleration(self):
+        """Computes the acceleration of the motor as thrust divided by mass."""
+        return self.thrust() / self.total_mass

rocketpy/rocket/rocket.py

@@ -24,7 +24,23 @@
 from rocketpy.rocket.parachute import Parachute
 from rocketpy.tools import parallel_axis_theorem_from_com
 
-
+class BaseRocket:
+    """Base class for a rocket model with minimal attributes and methods."""
+    def __init__(self, mass):
+        self.mass = mass
+        self.motor = None
+    def add_motor(self, motor):
+        self.motor = motor
+    def evaluate_total_mass(self):
+        if self.motor:
+            return self.mass + self.motor.total_mass
+        return self.mass
+
+class PointMassRocket(BaseRocket):
+    """Rocket modeled as a point mass for3-DOF simulations."""  
+    def __init__(self, mass, drag_coefficient=0):
+        super().__init__(mass)
+        self.drag_coefficient = drag_coefficient
 # pylint: disable=too-many-instance-attributes, too-many-public-methods, too-many-instance-attributes
 class Rocket:
     """Keeps rocket information.