ENH: add controllers to TimeNodes and add airbrakes drag calculation

rocketpy/simulation/flight.py

@@ -580,6 +580,7 @@ def __init__(
         if self.rail_length <= 0:
             raise ValueError("Rail length must be a positive value.")
         self.parachutes = self.rocket.parachutes[:]
+        self.controllers = self.rocket.controllers[:]
         self.inclination = inclination
         self.heading = heading
         self.max_time = max_time
@@ -654,6 +655,9 @@ def __init__(
                 phase.TimeNodes.add_parachutes(
                     self.parachutes, phase.t, phase.time_bound
                 )
+                phase.TimeNodes.add_controllers(
+                    self.controllers, phase.t, phase.time_bound
+                )
             # Add lst time node to permanent list
             phase.TimeNodes.add_node(phase.time_bound, [], [])
             # Sort time nodes
@@ -685,6 +689,9 @@ def __init__(
                 for callback in node.callbacks:
                     callback(self)
 
+                for controller in node.controllers:
+                    controller(self.t, self.y_sol)
+
                 for parachute in node.parachutes:
                     # Calculate and save pressure signal
                     pressure = self.env.pressure.get_value_opt(self.y_sol[2])
@@ -1698,6 +1705,8 @@ def u_dot_generalized(self, t, u, post_processing=False):
             drag_coeff = self.rocket.power_on_drag.get_value_opt(free_stream_mach)
         else:
             drag_coeff = self.rocket.power_off_drag.get_value_opt(free_stream_mach)
+        for airbrakes in self.rocket.airbrakes:
+            drag_coeff += airbrakes.cd_s
         R3 += -0.5 * rho * (free_stream_speed**2) * self.rocket.area * (drag_coeff)
 
         ## Off center moment
@@ -3472,6 +3481,20 @@ def add_parachutes(self, parachutes, t_init, t_end):
                 ]
                 self.list += parachute_node_list
 
+        def add_controllers(self, controllers, t_init, t_end):
+            # Iterate over controllers
+            for controller in controllers:
+                # Calculate start of sampling time nodes
+                controller_time_step = 1 / controller.sampling_rate
+                controller_node_list = [
+                    self.TimeNode(i * controller_time_step, [], [controller])
+                    for i in range(
+                        math.ceil(t_init / controller_time_step),
+                        math.floor(t_end / controller_time_step) + 1,
+                    )
+                ]
+                self.list += controller_node_list
+
         def sort(self):
             self.list.sort(key=(lambda node: node.t))
 
@@ -3495,10 +3518,11 @@ def flush_after(self, index):
             del self.list[index + 1 :]
 
         class TimeNode:
-            def __init__(self, t, parachutes, callbacks):
+            def __init__(self, t, parachutes, controllers):
                 self.t = t
                 self.parachutes = parachutes
-                self.callbacks = callbacks
+                self.callbacks = []
+                self.controllers = controllers
 
             def __repr__(self):
                 return (