ENH: adds new stability margin methods to flight

CHANGELOG.md

@@ -32,6 +32,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- ENH: Add new stability margin properties to Flight class [#572](https://github.com/RocketPy-Team/RocketPy/pull/572)
 - ENH: adds `Function.remove_outliers` method [#554](https://github.com/RocketPy-Team/RocketPy/pull/554)
 
 ### Changed

rocketpy/prints/flight_prints.py

@@ -33,42 +33,38 @@ def initial_conditions(self):
         -------
         None
         """
-
         print("\nInitial Conditions\n")
 
-        # Post-process results
-        if self.flight.post_processed is False:
-            self.flight.post_process()
+        t_init = self.flight.time[0]
+
+        print(f"Initial time: {t_init:.3f} s")
         print(
-            "Position - x: {:.2f} m | y: {:.2f} m | z: {:.2f} m".format(
-                self.flight.x(0), self.flight.y(0), self.flight.z(0)
-            )
+            f"Position - x: {self.flight.x(t_init):.2f} m | "
+            f"y: {self.flight.y(t_init):.2f} m | "
+            f"z: {self.flight.z(t_init):.2f} m"
         )
         print(
-            "Velocity - Vx: {:.2f} m/s | Vy: {:.2f} m/s | Vz: {:.2f} m/s".format(
-                self.flight.vx(0), self.flight.vy(0), self.flight.vz(0)
-            )
+            f"Velocity - Vx: {self.flight.vx(t_init):.2f} m/s | "
+            f"Vy: {self.flight.vy(t_init):.2f} m/s | "
+            f"Vz: {self.flight.vz(t_init):.2f} m/s"
         )
         print(
-            "Attitude - e0: {:.3f} | e1: {:.3f} | e2: {:.3f} | e3: {:.3f}".format(
-                self.flight.e0(0),
-                self.flight.e1(0),
-                self.flight.e2(0),
-                self.flight.e3(0),
-            )
+            f"Attitude (quaternions) - e0: {self.flight.e0(t_init):.3f} | "
+            f"e1: {self.flight.e1(t_init):.3f} | "
+            f"e2: {self.flight.e2(t_init):.3f} | "
+            f"e3: {self.flight.e3(t_init):.3f}"
         )
         print(
-            "Euler Angles - Spin φ : {:.2f}° | Nutation θ: {:.2f}° | Precession ψ: {:.2f}°".format(
-                self.flight.phi(0), self.flight.theta(0), self.flight.psi(0)
-            )
+            f"Euler Angles - Spin φ : {self.flight.phi(t_init):.2f}° | "
+            f"Nutation θ: {self.flight.theta(t_init):.2f}° | "
+            f"Precession ψ: {self.flight.psi(t_init):.2f}°"
         )
         print(
-            "Angular Velocity - ω1: {:.2f} rad/s | ω2: {:.2f} rad/s| ω3: {:.2f} rad/s".format(
-                self.flight.w1(0), self.flight.w2(0), self.flight.w3(0)
-            )
+            f"Angular Velocity - ω1: {self.flight.w1(t_init):.2f} rad/s | "
+            f"ω2: {self.flight.w2(t_init):.2f} rad/s | "
+            f"ω3: {self.flight.w3(t_init):.2f} rad/s"
         )
-
-        return None
+        print(f"Initial Stability Margin: {self.flight.initial_stability_margin:.3f} c")
 
     def numerical_integration_settings(self):
         """Prints out the Numerical Integration settings available about the
@@ -150,9 +146,8 @@ def out_of_rail_conditions(self):
         print("\nRail Departure State\n")
         print("Rail Departure Time: {:.3f} s".format(self.flight.out_of_rail_time))
         print(
-            "Rail Departure Velocity: {:.3f} m/s".format(
-                self.flight.out_of_rail_velocity
-            )
+            "Rail Departure Stability Margin: "
+            f"{self.flight.out_of_rail_stability_margin:.3f} c"
         )
         print(
             "Rail Departure Stability Margin: {:.3f} c".format(
@@ -408,9 +403,13 @@ def stability_margin(self):
         about the flight."""
         print("\nStability Margin\n")
         print(
-            "Maximum Stability Margin: {:.3f} c at {:.2f} s".format(
-                self.flight.max_stability_margin, self.flight.max_stability_margin_time
-            )
+            f"Initial Stability Margin: {self.flight.initial_stability_margin:.3f} c "
+            f"at {self.flight.time[0]:.2f} s"
+        )
+        print(
+            "Out of Rail Stability Margin: "
+            f"{self.flight.out_of_rail_stability_margin:.3f} c "
+            f"at {self.flight.out_of_rail_time:.2f} s"
         )
         print(
             "Minimum Stability Margin: {:.3f} c at {:.2f} s".format(

rocketpy/simulation/flight.py

@@ -426,6 +426,10 @@ class Flight:
         Rocket's static margin during flight in calibers.
     Flight.stability_margin : Function
             Rocket's stability margin during flight, in calibers.
+    Flight.initial_stability_margin : float
+        Rocket's initial stability margin in calibers.
+    Flight.out_of_rail_stability_margin : float
+        Rocket's stability margin in calibers when it leaves the rail.
     Flight.stream_velocity_x : Function
         Freestream velocity x (East) component, in m/s, as a function of
         time. Can be called or accessed as array.
@@ -2426,6 +2430,26 @@ def min_stability_margin(self):
         """Minimum stability margin."""
         return self.stability_margin(self.min_stability_margin_time)
 
+    @property
+    def initial_stability_margin(self):
+        """Stability margin at time 0.
+
+        Returns
+        -------
+        float
+        """
+        return self.stability_margin(self.time[0])
+
+    @property
+    def out_of_rail_stability_margin(self):
+        """Stability margin at the time the rocket leaves the rail.
+
+        Returns
+        -------
+        float
+        """
+        return self.stability_margin(self.out_of_rail_time)
+
     # Reynolds Number
     @funcify_method("Time (s)", "Reynolds Number", "spline", "zero")
     def reynolds_number(self):

tests/unit/test_flight.py

@@ -258,3 +258,31 @@ def test_get_controller_observed_variables(flight_calisto_air_brakes):
     obs_vars = flight_calisto_air_brakes.get_controller_observed_variables()
     assert isinstance(obs_vars, list)
     assert len(obs_vars) == 0
+
+
+def test_initial_stability_margin(flight_calisto_custom_wind):
+    """Test the initial_stability_margin method of the Flight class.
+
+    Parameters
+    ----------
+    flight_calisto_custom_wind : rocketpy.Flight
+    """
+    res = flight_calisto_custom_wind.initial_stability_margin
+    assert isinstance(res, float)
+    assert res == flight_calisto_custom_wind.stability_margin(0)
+    assert np.isclose(res, 2.05, atol=0.1)
+
+
+def test_out_of_rail_stability_margin(flight_calisto_custom_wind):
+    """Test the out_of_rail_stability_margin method of the Flight class.
+
+    Parameters
+    ----------
+    flight_calisto_custom_wind : rocketpy.Flight
+    """
+    res = flight_calisto_custom_wind.out_of_rail_stability_margin
+    assert isinstance(res, float)
+    assert res == flight_calisto_custom_wind.stability_margin(
+        flight_calisto_custom_wind.out_of_rail_time
+    )
+    assert np.isclose(res, 2.14, atol=0.1)