Enh/parachute

rocketpy/__init__.py

@@ -41,3 +41,4 @@
 from .SolidMotor import SolidMotor
 from .Rocket import Rocket
 from .Flight import Flight
+from .utilities import *

rocketpy/utilities.py

@@ -0,0 +1,50 @@
+# -*- coding: utf-8 -*-
+
+__author__ = "Franz Masatoshi Yuri"
+__copyright__ = "Copyright 20XX, Projeto Jupiter"
+__license__ = "MIT"
+
+import re
+import math
+import bisect
+import warnings
+import time
+from datetime import datetime, timedelta
+from inspect import signature, getsourcelines
+from collections import namedtuple
+
+import numpy as np
+from scipy import integrate
+from scipy import linalg
+import matplotlib.pyplot as plt
+from mpl_toolkits.mplot3d import Axes3D
+from matplotlib import cm
+
+from rocketpy import Environment, Rocket, SolidMotor, Flight
+
+
+def compute_cds_from_drop_test(final_speed, final_air_density, rocket_mass, gravity):
+    """Returns the parachute's Cds calculated through its final speed, air
+    density in the landing point, the rocket's mass and the force of gravity
+    in the landing point.
+
+    Parameters
+    ----------
+    final_speed : float
+        Rocket's speed in m/s^2 when landing.
+    final_air_density : float
+        Air density, in kg/m^3, right before the rocket lands.
+    rocket_mass : float
+        Rocket's mass in kg.
+    gravity : float
+        force of gravity in the landing point in newtons.
+
+    Returns
+    -------
+    cds : float
+        Number equal to drag coefficient times reference area for parachute.
+
+    """
+
+    cds = 2 * rocket_mass * gravity / ((final_speed ** 2) * final_air_density)
+    return cds