MNT: refactoring in flight.py and lint corrections to function.py and test_multidim_drag.py

-MNT:  removed unused velocity in body frame parameter requirement from all instances of get_drag_coefficient in flight.py

- MNT: corrected docstring for get_value_opt_grid in function.py

- MNT: shifted import of classes before the definition of functions in test_multidim_drag.py

Author: aZira371

rocketpy/mathutils/function.py

@@ -674,6 +674,8 @@ def __get_value_opt_nd(self, *args):
 
     def __get_value_opt_grid(self, *args):
         """Evaluate the Function using RegularGridInterpolator for structured grids.
+        
+        This method is dynamically assigned in from_grid() class method.
 
         Parameters
         ----------

rocketpy/simulation/flight.py

@@ -1379,9 +1379,7 @@ def lateral_surface_wind(self):
 
         return -wind_u * np.cos(heading_rad) + wind_v * np.sin(heading_rad)
 
-    def __get_drag_coefficient(
-        self, drag_function, mach, z, freestream_velocity_body
-    ):
+    def __get_drag_coefficient(self, drag_function, mach, z, freestream_velocity_body):
         """Calculate drag coefficient, handling both 1D and multi-dimensional functions.
 
         Parameters
@@ -1392,8 +1390,6 @@ def __get_drag_coefficient(
             Mach number
         z : float
             Altitude in meters
-        velocity_body : Vector or array-like
-            Rocket velocity in body frame [vx_b, vy_b, vz_b]
         freestream_velocity_body : Vector or array-like
             Freestream velocity in body frame [stream_vx_b, stream_vy_b, stream_vz_b]
 
@@ -1517,7 +1513,6 @@ def udot_rail1(self, t, u, post_processing=False):
             self.rocket.power_on_drag,
             free_stream_mach,
             z,
-            [vx_b, vy_b, vz_b],
             [stream_vx_b, stream_vy_b, stream_vz_b],
         )
 
@@ -1712,15 +1707,13 @@ def u_dot(self, t, u, post_processing=False):  # pylint: disable=too-many-locals
                 self.rocket.power_on_drag,
                 free_stream_mach,
                 z,
-                [vx_b, vy_b, vz_b],
                 [stream_vx_b, stream_vy_b, stream_vz_b],
             )
         else:
             drag_coeff = self.__get_drag_coefficient(
                 self.rocket.power_off_drag,
                 free_stream_mach,
                 z,
-                [vx_b, vy_b, vz_b],
                 [stream_vx_b, stream_vy_b, stream_vz_b],
             )
         rho = self.env.density.get_value_opt(z)
@@ -2125,7 +2118,6 @@ def u_dot_generalized(self, t, u, post_processing=False):  # pylint: disable=too
                 self.rocket.power_on_drag,
                 free_stream_mach,
                 z,
-                velocity_in_body_frame,
                 freestream_velocity_body,
             )
         else:
@@ -2134,7 +2126,6 @@ def u_dot_generalized(self, t, u, post_processing=False):  # pylint: disable=too
                 self.rocket.power_off_drag,
                 free_stream_mach,
                 z,
-                velocity_in_body_frame,
                 freestream_velocity_body,
             )
         R3 += -0.5 * rho * (free_stream_speed**2) * self.rocket.area * drag_coeff

tests/integration/test_multidim_drag.py

@@ -1,14 +1,12 @@
 """Integration tests for multi-dimensional drag coefficient support."""
 
 import numpy as np
-import pytest
 
-from rocketpy import Function
+from rocketpy import Environment, Flight, Function, Rocket, SolidMotor
 
 
 def test_flight_with_1d_drag(example_plain_env, calisto):
     """Test that flights with 1D drag curves still work (backward compatibility)."""
-    from rocketpy import Flight
 
     flight = Flight(
         rocket=calisto,
@@ -26,8 +24,6 @@ def test_flight_with_1d_drag(example_plain_env, calisto):
 
 def test_flight_with_3d_drag_basic():
     """Test that a simple 3D drag function works."""
-    from rocketpy import Environment, Flight, Rocket, SolidMotor
-
     # Create environment
     env = Environment(gravity=9.81)
     env.set_atmospheric_model(type="standard_atmosphere")