ENH: changing parameter ka to added_mass_coefficient

Author: ArthurJWH

rocketpy/rocket/parachute.py

@@ -103,6 +103,9 @@ class Parachute:
         in [0, 1]. Affects only the added-mass scaling during descent; it does
         not change ``cd_s`` (drag). The default, 0.0432, yields an added-mass
         of 1.0 (“neutral” behavior).
+    Parachute.added_mass_coefficient : float
+        Coefficient used to calculate the added-mass due to dragged air. It is
+        calculated from the porosity of the parachute.
     """
 
     def __init__(
@@ -200,7 +203,7 @@ def __init__(
         self.radius = radius
         self.height = height or radius
         self.porosity = porosity
-        self.ka = 1.068 * (
+        self.added_mass_coefficient = 1.068 * (
             1
             - 1.465 * self.porosity
             - 0.25975 * self.porosity**2

rocketpy/simulation/flight.py

@@ -777,7 +777,7 @@ def __simulate(self, verbose):
                             lambda self, parachute_porosity=parachute.porosity: setattr(
                                 self, "parachute_porosity", parachute_porosity
                             ),
-                            lambda self, ka=parachute.ka: setattr(
+                            lambda self, ka=parachute.added_mass_coefficient: setattr(
                                 self, "parachute_ka", ka
                             ),
                         ]
@@ -1044,7 +1044,8 @@ def __simulate(self, verbose):
                                                 "parachute_porosity",
                                                 parachute_porosity,
                                             ),
-                                            lambda self, ka=parachute.ka: setattr(
+                                            lambda self,
+                                            ka=parachute.added_mass_coefficient: setattr(
                                                 self, "ka", ka
                                             ),
                                         ]
@@ -2012,7 +2013,7 @@ def u_dot_parachute(self, t, u, post_processing=False):
 
         # Calculate added mass
         ma = (
-            self.ka
+            self.added_mass_coefficient
             * rho
             * (2 / 3)
             * np.pi