ENH: net thrust method extended to the rest of the motor classes

Author: kevin-alcaniz

rocketpy/motors/empty_motor.py

@@ -13,6 +13,7 @@ def __init__(self):
             dry_inertia=(0, 0, 0),
             nozzle_radius=0,
             center_of_dry_mass_position=0,
+            reference_pressure=0,
             dry_mass=0,
             nozzle_position=0,
             burn_time=1,

rocketpy/motors/hybrid_motor.py

@@ -29,6 +29,8 @@ class HybridMotor(Motor):
         "combustion_chamber_to_nozzle".
     HybridMotor.nozzle_radius : float
         Radius of motor nozzle outlet in meters.
+    HybridMotor.nozzle_area : float
+        Area of motor nozzle outlet in square meters.
     HybridMotor.nozzle_position : float
         Motor's nozzle outlet position in meters, specified in the motor's
         coordinate system. See
@@ -147,7 +149,11 @@ class HybridMotor(Motor):
         HybridMotor.propellant_I_22 and HybridMotor.propellant_I_33 for
         more information.
     HybridMotor.thrust : Function
-        Motor thrust force, in Newtons, as a function of time.
+        Motor thrust force obtained from thrust source, in Newtons, as a
+        function of time.
+    HybridMotor.vacuum_thrust : Function
+        Motor thrust force when the rocket is in a vacuum. In Newtons, as a
+        function of time.
     HybridMotor.total_impulse : float
         Total impulse of the thrust curve in N*s.
     HybridMotor.max_thrust : float
@@ -181,6 +187,9 @@ class HybridMotor(Motor):
         Method of interpolation used in case thrust curve is given
         by data set in .csv or .eng, or as an array. Options are 'spline'
         'akima' and 'linear'. Default is "linear".
+    HybridMotor.reference_pressure : int, float
+        Atmospheric pressure in Pa at which the thrust data was recorded.
+        It will allow to obtain the net thrust in the Flight class.
     """
 
     def __init__(  # pylint: disable=too-many-arguments
@@ -197,6 +206,7 @@ def __init__(  # pylint: disable=too-many-arguments
         grain_separation,
         grains_center_of_mass_position,
         center_of_dry_mass_position,
+        reference_pressure=None,
         nozzle_position=0,
         burn_time=None,
         throat_radius=0.01,
@@ -258,6 +268,8 @@ class Function. Thrust units are Newtons.
             The position, in meters, of the motor's center of mass with respect
             to the motor's coordinate system when it is devoid of propellant.
             See :doc:`Positions and Coordinate Systems </user/positions>`.
+        reference_pressure : int, float, optional
+            Atmospheric pressure in Pa at which the thrust data was recorded.
         nozzle_position : int, float, optional
             Motor's nozzle outlet position in meters, in the motor's coordinate
             system. See :doc:`Positions and Coordinate Systems </user/positions>`
@@ -308,6 +320,7 @@ class Function. Thrust units are Newtons.
             dry_inertia=dry_inertia,
             nozzle_radius=nozzle_radius,
             center_of_dry_mass_position=center_of_dry_mass_position,
+            reference_pressure=reference_pressure,
             dry_mass=dry_mass,
             nozzle_position=nozzle_position,
             burn_time=burn_time,
@@ -321,6 +334,7 @@ class Function. Thrust units are Newtons.
             dry_inertia,
             nozzle_radius,
             center_of_dry_mass_position,
+            reference_pressure,
             nozzle_position,
             burn_time,
             reshape_thrust_curve,
@@ -340,6 +354,7 @@ class Function. Thrust units are Newtons.
             grain_separation,
             grains_center_of_mass_position,
             center_of_dry_mass_position,
+            reference_pressure,
             nozzle_position,
             burn_time,
             throat_radius,
@@ -657,6 +672,7 @@ def from_dict(cls, data):
             nozzle_radius=data["nozzle_radius"],
             dry_mass=data["dry_mass"],
             center_of_dry_mass_position=data["center_of_dry_mass_position"],
+            reference_pressure=data["reference_pressure"],
             dry_inertia=(
                 data["dry_I_11"],
                 data["dry_I_22"],

rocketpy/motors/liquid_motor.py

@@ -29,6 +29,8 @@ class LiquidMotor(Motor):
         "combustion_chamber_to_nozzle".
     LiquidMotor.nozzle_radius : float
         Radius of motor nozzle outlet in meters.
+    LiquidMotor.nozzle_area : float
+        Area of motor nozzle outlet in square meters.
     LiquidMotor.nozzle_position : float
         Motor's nozzle outlet position in meters, specified in the motor's
         coordinate system. See
@@ -122,7 +124,11 @@ class LiquidMotor(Motor):
         LiquidMotor.propellant_I_22 and LiquidMotor.propellant_I_33 for
         more information.
     LiquidMotor.thrust : Function
-        Motor thrust force, in Newtons, as a function of time.
+        Motor thrust force obtained from thrust source, in Newtons, as a
+        function of time.
+    LiquidMotor.vacuum_thrust : Function
+        Motor thrust force when the rocket is in a vacuum. In Newtons, as a
+        function of time.
     LiquidMotor.total_impulse : float
         Total impulse of the thrust curve in N*s.
     LiquidMotor.max_thrust : float
@@ -143,6 +149,9 @@ class LiquidMotor(Motor):
         burn_out_time and the burn_start_time.
     LiquidMotor.exhaust_velocity : Function
         Propulsion gases exhaust velocity in m/s.
+    LiquidMotor.reference_pressure : int, float
+        Atmospheric pressure in Pa at which the thrust data was recorded.
+        It will allow to obtain the net thrust in the Flight class.
     """
 
     def __init__(
@@ -152,6 +161,7 @@ def __init__(
         dry_inertia,
         nozzle_radius,
         center_of_dry_mass_position,
+        reference_pressure=None,
         nozzle_position=0,
         burn_time=None,
         reshape_thrust_curve=False,
@@ -194,6 +204,8 @@ class Function. Thrust units are Newtons.
             The position, in meters, of the motor's center of mass with respect
             to the motor's coordinate system when it is devoid of propellant.
             See :doc:`Positions and Coordinate Systems </user/positions>`
+        reference_pressure : int, float, optional
+            Atmospheric pressure in Pa at which the thrust data was recorded.
         nozzle_position : float
             Motor's nozzle outlet position in meters, specified in the motor's
             coordinate system. See
@@ -236,6 +248,7 @@ class Function. Thrust units are Newtons.
             dry_inertia=dry_inertia,
             nozzle_radius=nozzle_radius,
             center_of_dry_mass_position=center_of_dry_mass_position,
+            reference_pressure=reference_pressure,
             dry_mass=dry_mass,
             nozzle_position=nozzle_position,
             burn_time=burn_time,
@@ -500,6 +513,7 @@ def from_dict(cls, data):
             nozzle_radius=data["nozzle_radius"],
             dry_mass=data["dry_mass"],
             center_of_dry_mass_position=data["center_of_dry_mass_position"],
+            reference_pressure=data["reference_pressure"],
             dry_inertia=(
                 data["dry_I_11"],
                 data["dry_I_22"],

rocketpy/motors/motor.py

@@ -1227,6 +1227,7 @@ class GenericMotor(Motor):
     therefore for more accurate results, use the ``SolidMotor``, ``HybridMotor``
     or ``LiquidMotor`` classes."""
 
+    # pylint: disable=too-many-arguments
     def __init__(
         self,
         thrust_source,
@@ -1236,6 +1237,7 @@ def __init__(
         chamber_position,
         propellant_initial_mass,
         nozzle_radius,
+        reference_pressure=None,
         dry_mass=0,
         center_of_dry_mass_position=None,
         dry_inertia=(0, 0, 0),
@@ -1282,6 +1284,8 @@ def __init__(
             to the motor's coordinate system when it is devoid of propellant.
             If not specified, automatically sourced as the chamber position.
             See :doc:`Positions and Coordinate Systems </user/positions>`
+        reference_pressure : int, float, optional
+            Atmospheric pressure in Pa at which the thrust data was recorded.
         dry_inertia : tuple, list
             Tuple or list containing the motor's dry mass inertia tensor
             components, in kg*m^2. This inertia is defined with respect to the
@@ -1338,6 +1342,7 @@ def __init__(
             dry_inertia=dry_inertia,
             nozzle_radius=nozzle_radius,
             center_of_dry_mass_position=center_of_dry_mass_position,
+            reference_pressure=reference_pressure,
             dry_mass=dry_mass,
             nozzle_position=nozzle_position,
             burn_time=burn_time,
@@ -1500,6 +1505,7 @@ def load_from_eng_file(
         dry_mass=None,
         burn_time=None,
         center_of_dry_mass_position=None,
+        reference_pressure=None,
         dry_inertia=(0, 0, 0),
         nozzle_position=0,
         reshape_thrust_curve=False,
@@ -1541,6 +1547,8 @@ def load_from_eng_file(
             The position, in meters, of the motor's center of mass with respect
             to the motor's coordinate system when it is devoid of propellant.
             If not specified, automatically sourced as the chamber position.
+        reference_pressure : int, float, optional
+            Atmospheric pressure in Pa at which the thrust data was recorded.
         dry_inertia : tuple, list
             Tuple or list containing the motor's dry mass inertia tensor
         nozzle_position : int, float, optional
@@ -1608,6 +1616,7 @@ def load_from_eng_file(
             chamber_position=chamber_position,
             propellant_initial_mass=propellant_initial_mass,
             nozzle_radius=nozzle_radius,
+            reference_pressure=reference_pressure,
             dry_mass=dry_mass,
             center_of_dry_mass_position=center_of_dry_mass_position,
             dry_inertia=dry_inertia,
@@ -1645,6 +1654,7 @@ def from_dict(cls, data):
             chamber_position=data["chamber_position"],
             propellant_initial_mass=data["propellant_initial_mass"],
             nozzle_radius=data["nozzle_radius"],
+            reference_pressure=data["reference_pressure"],
             dry_mass=data["dry_mass"],
             center_of_dry_mass_position=data["center_of_dry_mass_position"],
             dry_inertia=(

rocketpy/motors/solid_motor.py

@@ -808,6 +808,7 @@ def from_dict(cls, data):
             grain_separation=data["grain_separation"],
             grains_center_of_mass_position=data["grains_center_of_mass_position"],
             center_of_dry_mass_position=data["center_of_dry_mass_position"],
+            reference_pressure=data["reference_pressure"],
             nozzle_position=data["nozzle_position"],
             burn_time=data["burn_time"],
             throat_radius=data["throat_radius"],