From 481551231e624fc165d94f8b2485824cbce4b79e Mon Sep 17 00:00:00 2001
From: Gui-FernandesBR <guilherme_fernandes@usp.br>
Date: Fri, 8 Mar 2024 11:27:48 -0500
Subject: [PATCH] MNT: apply parallel_axis_theorem function to hybrid and
 liquid motors

---
 rocketpy/motors/hybrid_motor.py | 31 +++++++++++++++----------------
 rocketpy/motors/liquid_motor.py |  8 +++-----
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/rocketpy/motors/hybrid_motor.py b/rocketpy/motors/hybrid_motor.py
index 4b28a96d2..0320c9f3c 100644
--- a/rocketpy/motors/hybrid_motor.py
+++ b/rocketpy/motors/hybrid_motor.py
@@ -1,3 +1,5 @@
+from rocketpy.tools import parallel_axis_theorem
+
 from ..mathutils.function import Function, funcify_method, reset_funcified_methods
 from ..plots.hybrid_motor_plots import _HybridMotorPlots
 from ..prints.hybrid_motor_prints import _HybridMotorPrints
@@ -455,23 +457,20 @@ def propellant_I_11(self):
         ----------
         .. [1] https://en.wikipedia.org/wiki/Moment_of_inertia#Inertia_tensor
         """
-        solid_correction = (
-            self.solid.propellant_mass
-            * (self.solid.center_of_propellant_mass - self.center_of_propellant_mass)
-            ** 2
-        )
-        liquid_correction = (
-            self.liquid.propellant_mass
-            * (self.liquid.center_of_propellant_mass - self.center_of_propellant_mass)
-            ** 2
-        )
 
-        I_11 = (
-            self.solid.propellant_I_11
-            + solid_correction
-            + self.liquid.propellant_I_11
-            + liquid_correction
-        )
+        solid_mass = self.solid.propellant_mass
+        liquid_mass = self.liquid.propellant_mass
+
+        cm = self.center_of_propellant_mass
+        solid_cm_to_cm = self.solid.center_of_propellant_mass - cm
+        liquid_cm_to_cm = self.liquid.center_of_propellant_mass - cm
+
+        solid_prop_inertia = self.solid.propellant_I_11
+        liquid_prop_inertia = self.liquid.propellant_I_11
+
+        I_11 = parallel_axis_theorem(
+            solid_prop_inertia, solid_mass, solid_cm_to_cm
+        ) + parallel_axis_theorem(liquid_prop_inertia, liquid_mass, liquid_cm_to_cm)
 
         return I_11
 
diff --git a/rocketpy/motors/liquid_motor.py b/rocketpy/motors/liquid_motor.py
index ac525b379..62caa44e7 100644
--- a/rocketpy/motors/liquid_motor.py
+++ b/rocketpy/motors/liquid_motor.py
@@ -7,6 +7,7 @@
     funcify_method,
     reset_funcified_methods,
 )
+from rocketpy.tools import parallel_axis_theorem
 
 from ..plots.liquid_motor_plots import _LiquidMotorPlots
 from ..prints.liquid_motor_prints import _LiquidMotorPrints
@@ -388,11 +389,8 @@ def propellant_I_11(self):
         for positioned_tank in self.positioned_tanks:
             tank = positioned_tank.get("tank")
             tank_position = positioned_tank.get("position")
-            I_11 += (
-                tank.inertia
-                + tank.fluid_mass
-                * (tank_position + tank.center_of_mass - center_of_mass) ** 2
-            )
+            distance = tank_position + tank.center_of_mass - center_of_mass
+            I_11 += parallel_axis_theorem(tank.inertia, tank.fluid_mass, distance)
 
         return I_11