ENH: add prandtl-glauert rule to nose cone and tail

rocketpy/rocket/aero_surface.py

@@ -34,6 +34,30 @@ def __init__(self, name):
         self.name = name
         return None
 
+    # Defines beta parameter
+    def _beta(_, mach):
+        """Defines a parameter that is often used in aerodynamic
+        equations. It is commonly used in the Prandtl factor which
+        corrects subsonic force coefficients for compressible flow.
+
+        Parameters
+        ----------
+        mach : int, float
+            Number of mach.
+
+        Returns
+        -------
+        beta : int, float
+            Value that characterizes flow speed based on the mach number.
+        """
+
+        if mach < 0.8:
+            return np.sqrt(1 - mach**2)
+        elif mach < 1.1:
+            return np.sqrt(1 - 0.8**2)
+        else:
+            return np.sqrt(mach**2 - 1)
+
     @abstractmethod
     def evaluate_center_of_pressure(self):
         """Evaluates the center of pressure of the aerodynamic surface in local
@@ -465,7 +489,7 @@ def evaluate_lift_coefficient(self):
         # It must be set as a Function because it will be called and treated
         # as a function of mach in the simulation.
         self.clalpha = Function(
-            lambda mach: 2 * self.radius_ratio**2,
+            lambda mach: 2 / self._beta(mach) * self.radius_ratio**2,
             "Mach",
             f"Lift coefficient derivative for {self.name}",
         )
@@ -781,7 +805,7 @@ def evaluate_lift_coefficient(self):
                 clalpha2D_incompressible *= 180 / np.pi
 
         # Correcting for compressible flow (apply Prandtl-Glauert correction)
-        clalpha2D = Function(lambda mach: clalpha2D_incompressible / self.__beta(mach))
+        clalpha2D = Function(lambda mach: clalpha2D_incompressible / self._beta(mach))
 
         # Diederich's Planform Correlation Parameter
         FD = 2 * np.pi * self.AR / (clalpha2D * np.cos(self.gamma_c))
@@ -857,30 +881,6 @@ def evaluate_roll_parameters(self):
         self.roll_parameters = [clf_delta, cld_omega, self.cant_angle_rad]
         return self.roll_parameters
 
-    # Defines beta parameter
-    def __beta(_, mach):
-        """Defines a parameter that is often used in aerodynamic
-        equations. It is commonly used in the Prandtl factor which
-        corrects subsonic force coefficients for compressible flow.
-
-        Parameters
-        ----------
-        mach : int, float
-            Number of mach.
-
-        Returns
-        -------
-        beta : int, float
-            Value that characterizes flow speed based on the mach number.
-        """
-
-        if mach < 0.8:
-            return np.sqrt(1 - mach**2)
-        elif mach < 1.1:
-            return np.sqrt(1 - 0.8**2)
-        else:
-            return np.sqrt(mach**2 - 1)
-
     # Defines number of fins  factor
     def __fin_num_correction(_, n):
         """Calculates a correction factor for the lift coefficient of multiple
@@ -1748,6 +1748,7 @@ def evaluate_lift_coefficient(self):
         # as a function of mach in the simulation.
         self.clalpha = Function(
             lambda mach: 2
+            / self._beta(mach)
             * (
                 (self.bottom_radius / self.rocket_radius) ** 2
                 - (self.top_radius / self.rocket_radius) ** 2