Gravity v4

aviary/api.py

@@ -55,9 +55,7 @@
 )
 from aviary.utils.options import list_options
 from aviary.constants import (
-    GRAV_ENGLISH_GASP,
     GRAV_ENGLISH_LBM,
-    GRAV_METRIC_GASP,
     PSLS_PSF,
     TSLS_DEGR,
 )

aviary/constants.py

@@ -5,32 +5,40 @@
 GRAV_EARTH = (
     9.80665,
     'm/s**2',
-)  # NIST https://physics.nist.gov/cgi-bin/cuu/Value?gn|search_for=gravity
+)
+# NIST https://physics.nist.gov/cgi-bin/cuu/Value?gn|search_for=gravity
+
 GRAV_MARS = (
     3.712,
     'm/s**2',
-)  # Mars Global Reference Atmospheric Model (Mars-GRAM) 2024: User Guide, NASA/TM-20240012934
+)
+# Mars Global Reference Atmospheric Model (Mars-GRAM) 2024: User Guide, NASA/TM-20240012934
+
 GRAV_VENUS = (
     8.870,
     'm/s**2',
-)  # Venus Global Reference Atmospheric Model (Venus-GRAM): User Guide, NASA/TM-20210022168
+)
+# Venus Global Reference Atmospheric Model (Venus-GRAM): User Guide, NASA/TM-20210022168
 
-RADIUS_EARTH = (6371009, 'm')  # Source: GRS80, mean earth radius (rounded to nearest meter)
-# convert_geopotential_altitude() is a python utility function that require RADIUS_EARTH to be specified in meters!
+RADIUS_EARTH = (
+    6371009.0,
+    'm',
+)  # Source: GRS80, mean earth radius (rounded to nearest meter)
+# convert_geopotential_altitude() is a python utility function for engine decs that require RADIUS_EARTH to be specified in meters!
 
 RADIUS_MARS = (
-    3386200,
+    3386200.0,
     'm',
-)  # Mars Global Reference Atmospheric Model (Mars-GRAM) 2024: User Guide, NASA/TM-20240012934, avg of equatorial and polar radius
+)
+# Mars Global Reference Atmospheric Model (Mars-GRAM) 2024: User Guide, NASA/TM-20240012934, avg of equatorial and polar radius
+
 RADIUS_VENUS = (
-    6051800,
+    6051800.0,
     'm',
-)  # Venus Global Reference Atmospheric Model (Venus-GRAM): User Guide, NASA/TM-20210022168, avg of equatorial and polar radius
+)
+# Venus Global Reference Atmospheric Model (Venus-GRAM): User Guide, NASA/TM-20210022168, avg of equatorial and polar radius
 
-# GNS = 9.8236930  # grav_accel_at_surface_earth # TODO: Remove this from other parts of Aviary
-GRAV_METRIC_GASP = 9.81  # m/s^2
-GRAV_ENGLISH_GASP = 32.2  # ft/s^2
-GRAV_ENGLISH_LBM = 1.0  # lbf/lbm
+GRAV_ENGLISH_LBM = 1.0  # lbf/lbm, Only valid for earth sea level conversions!
 
 # sea level standard pressure in psf
 PSLS_PSF = 2116.22

aviary/mission/energy_state/ode/landing_eom.py

@@ -9,7 +9,6 @@
     FlightPathAngleRate,
     VelocityRate,
 )
-from aviary.utils.aviary_values import AviaryValues
 from aviary.variable_info.functions import add_aviary_input, add_aviary_option
 from aviary.variable_info.variables import Dynamic, Mission
 

aviary/mission/solved_two_dof/ode/groundroll_eom.py

@@ -1,8 +1,8 @@
 import numpy as np
 import openmdao.api as om
 
-from aviary.constants import GRAV_ENGLISH_GASP, GRAV_ENGLISH_LBM
-from aviary.variable_info.functions import add_aviary_input, add_aviary_output
+from aviary.constants import GRAV_ENGLISH_LBM
+from aviary.variable_info.functions import add_aviary_input, add_aviary_output, add_aviary_option
 from aviary.variable_info.variables import Aircraft, Dynamic, Mission
 
 
@@ -12,6 +12,8 @@ class GroundrollEOM(om.ExplicitComponent):
     def initialize(self):
         self.options.declare('num_nodes', types=int)
 
+        add_aviary_option(self, Mission.GRAVITY, units='ft/s**2')
+
     def setup(self):
         nn = self.options['num_nodes']
 
@@ -133,8 +135,9 @@ def setup_partials(self):
         self.declare_partials('angle_of_attack_rate', ['*'])
 
     def compute(self, inputs, outputs):
-        mu = inputs[Mission.Takeoff.ROLLING_FRICTION_COEFFICIENT]
+        grav_english = self.options[Mission.GRAVITY][0]
 
+        mu = inputs[Mission.Takeoff.ROLLING_FRICTION_COEFFICIENT]
         weight = inputs[Dynamic.Vehicle.MASS] * GRAV_ENGLISH_LBM
         thrust = inputs[Dynamic.Vehicle.Propulsion.THRUST_TOTAL]
         incremented_lift = inputs[Dynamic.Vehicle.LIFT]
@@ -158,7 +161,7 @@ def compute(self, inputs, outputs):
                 - weight * np.sin(gamma)
                 - mu * normal_force
             )
-            * GRAV_ENGLISH_GASP
+            * grav_english
             / weight
         )
         outputs[Dynamic.Mission.FLIGHT_PATH_ANGLE_RATE] = np.zeros(nn)
@@ -171,8 +174,9 @@ def compute(self, inputs, outputs):
         outputs['angle_of_attack_rate'] = np.zeros(nn)
 
     def compute_partials(self, inputs, J):
-        mu = inputs[Mission.Takeoff.ROLLING_FRICTION_COEFFICIENT]
+        grav_english = self.options[Mission.GRAVITY][0]
 
+        mu = inputs[Mission.Takeoff.ROLLING_FRICTION_COEFFICIENT]
         weight = inputs[Dynamic.Vehicle.MASS] * GRAV_ENGLISH_LBM
         thrust = inputs[Dynamic.Vehicle.Propulsion.THRUST_TOTAL]
         incremented_lift = inputs[Dynamic.Vehicle.LIFT]
@@ -214,17 +218,17 @@ def compute_partials(self, inputs, J):
         dNF_dIwing[normal_force1 < 0] = 0
 
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.Propulsion.THRUST_TOTAL] = (
-            (dTAlF_dThrust - mu * dNF_dThrust) * GRAV_ENGLISH_GASP / weight
+            (dTAlF_dThrust - mu * dNF_dThrust) * grav_english / weight
         )
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.ANGLE_OF_ATTACK] = (
-            (dTAlF_dAlpha - mu * dNF_dAlpha) * GRAV_ENGLISH_GASP / weight
+            (dTAlF_dAlpha - mu * dNF_dAlpha) * grav_english / weight
         )
         J[Dynamic.Mission.VELOCITY_RATE, Aircraft.Wing.INCIDENCE] = (
-            (dTAlF_dIwing - mu * dNF_dIwing) * GRAV_ENGLISH_GASP / weight
+            (dTAlF_dIwing - mu * dNF_dIwing) * grav_english / weight
         )
-        J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.DRAG] = -GRAV_ENGLISH_GASP / weight
+        J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.DRAG] = -grav_english / weight
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.MASS] = (
-            GRAV_ENGLISH_GASP
+            grav_english
             * GRAV_ENGLISH_LBM
             * (
                 weight * (-np.sin(gamma) - mu * dNF_dWeight)
@@ -238,13 +242,13 @@ def compute_partials(self, inputs, J):
             / weight**2
         )
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Mission.FLIGHT_PATH_ANGLE] = (
-            -np.cos(gamma) * GRAV_ENGLISH_GASP
+            -np.cos(gamma) * grav_english
         )
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.LIFT] = (
-            GRAV_ENGLISH_GASP * (-mu * dNF_dLift) / weight
+            grav_english * (-mu * dNF_dLift) / weight
         )
         J[Dynamic.Mission.VELOCITY_RATE, Mission.Takeoff.ROLLING_FRICTION_COEFFICIENT] = (
-            (-normal_force) * GRAV_ENGLISH_GASP / weight
+            (-normal_force) * grav_english / weight
         )
 
         J[Dynamic.Mission.ALTITUDE_RATE, Dynamic.Mission.VELOCITY] = np.sin(gamma)

aviary/mission/solved_two_dof/ode/test/test_groundroll_eom.py

@@ -13,7 +13,10 @@
 class GroundrollEOMTestCase(unittest.TestCase):
     def setUp(self):
         self.prob = om.Problem()
-        self.prob.model.add_subsystem('group', GroundrollEOM(num_nodes=2), promotes=['*'])
+        options = {Mission.GRAVITY: (32.2, 'ft/s**2')}
+        self.prob.model.add_subsystem(
+            'group', GroundrollEOM(num_nodes=2, **options), promotes=['*']
+        )
         self.prob.model.set_input_defaults(
             Dynamic.Vehicle.MASS, val=175400 * np.ones(2), units='lbm'
         )

aviary/mission/solved_two_dof/ode/test/test_groundroll_ode.py

@@ -11,7 +11,7 @@
 from aviary.utils.test_utils.IO_test_util import check_prob_outputs
 from aviary.variable_info.functions import setup_model_options
 from aviary.variable_info.options import get_option_defaults
-from aviary.variable_info.variables import Aircraft, Dynamic
+from aviary.variable_info.variables import Aircraft, Dynamic, Mission
 
 
 @use_tempdirs
@@ -23,6 +23,7 @@ def setUp(self):
 
         aviary_options = get_option_defaults()
         aviary_options.set_val(Aircraft.Engine.GLOBAL_THROTTLE, True)
+        aviary_options.set_val(Mission.GRAVITY, val=32.2, units='ft/s**2')
         default_mission_subsystems = get_default_mission_subsystems(
             'GASP', [build_engine_deck(aviary_options)]
         )

aviary/mission/solved_two_dof/ode/unsteady_solved_eom.py

@@ -2,8 +2,8 @@
 import openmdao.api as om
 from openmdao.utils.units import convert_units
 
-from aviary.constants import GRAV_ENGLISH_LBM, GRAV_METRIC_GASP
-from aviary.variable_info.functions import add_aviary_input
+from aviary.constants import GRAV_ENGLISH_LBM
+from aviary.variable_info.functions import add_aviary_input, add_aviary_option
 from aviary.variable_info.variables import Aircraft, Dynamic, Mission
 
 LBF_TO_N = convert_units(1.0, 'lbf', 'N')
@@ -31,6 +31,8 @@ def initialize(self):
             'the TAS rate equation.',
         )
 
+        add_aviary_option(self, Mission.GRAVITY, units='m/s**2')
+
     def setup(self):
         nn = self.options['num_nodes']
 
@@ -214,6 +216,8 @@ def setup_partials(self):
             self.declare_partials(of=['dgam_dt_approx', 'dgam_dt'], wrt=[Aircraft.Wing.INCIDENCE])
 
     def compute(self, inputs, outputs):
+        grav_metric = self.options[Mission.GRAVITY][0]
+
         tas = inputs[Dynamic.Mission.VELOCITY]
         thrust = inputs[Dynamic.Vehicle.Propulsion.THRUST_TOTAL]
         # convert to newtons  # TODO: change this to use the units conversion
@@ -224,7 +228,7 @@ def compute(self, inputs, outputs):
 
         i_wing = inputs[Aircraft.Wing.INCIDENCE]
 
-        g = GRAV_METRIC_GASP
+        g = grav_metric
         m = weight / g
 
         if self.options['ground_roll']:
@@ -269,6 +273,7 @@ def compute(self, inputs, outputs):
             outputs['dgam_dt_approx'] = dgam_dr * dr_dt
 
     def compute_partials(self, inputs, partials):
+        grav_metric = self.options[Mission.GRAVITY][0]
         ground_roll = self.options['ground_roll']
 
         thrust = inputs[Dynamic.Vehicle.Propulsion.THRUST_TOTAL]
@@ -291,7 +296,7 @@ def compute_partials(self, inputs, partials):
 
         alpha_i = alpha - i_wing
 
-        g = GRAV_METRIC_GASP
+        g = grav_metric
         m = weight / g
 
         mtas = m * tas

aviary/mission/two_dof/ode/accel_eom.py

@@ -1,9 +1,9 @@
 import numpy as np
 import openmdao.api as om
 
-from aviary.constants import GRAV_ENGLISH_GASP, GRAV_ENGLISH_LBM
-from aviary.variable_info.functions import add_aviary_input, add_aviary_output
-from aviary.variable_info.variables import Dynamic
+from aviary.constants import GRAV_ENGLISH_LBM
+from aviary.variable_info.functions import add_aviary_input, add_aviary_output, add_aviary_option
+from aviary.variable_info.variables import Dynamic, Mission
 
 
 class AccelerationRates(om.ExplicitComponent):
@@ -16,6 +16,8 @@ class AccelerationRates(om.ExplicitComponent):
     def initialize(self):
         self.options.declare('num_nodes', types=int)
 
+        add_aviary_option(self, Mission.GRAVITY, units='ft/s**2')
+
     def setup(self):
         nn = self.options['num_nodes']
 
@@ -79,23 +81,26 @@ def setup_partials(self):
         )
 
     def compute(self, inputs, outputs):
+        grav_english = self.options[Mission.GRAVITY][0]
+
         weight = inputs[Dynamic.Vehicle.MASS] * GRAV_ENGLISH_LBM
         drag = inputs[Dynamic.Vehicle.DRAG]
         thrust = inputs[Dynamic.Vehicle.Propulsion.THRUST_TOTAL]
         TAS = inputs[Dynamic.Mission.VELOCITY]
 
-        outputs[Dynamic.Mission.VELOCITY_RATE] = (GRAV_ENGLISH_GASP / weight) * (thrust - drag)
+        outputs[Dynamic.Mission.VELOCITY_RATE] = (grav_english / weight) * (thrust - drag)
         outputs[Dynamic.Mission.DISTANCE_RATE] = TAS
 
     def compute_partials(self, inputs, J):
+        grav_english = self.options[Mission.GRAVITY][0]
         weight = inputs[Dynamic.Vehicle.MASS] * GRAV_ENGLISH_LBM
         drag = inputs[Dynamic.Vehicle.DRAG]
         thrust = inputs[Dynamic.Vehicle.Propulsion.THRUST_TOTAL]
 
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.MASS] = (
-            -(GRAV_ENGLISH_GASP / weight**2) * (thrust - drag) * GRAV_ENGLISH_LBM
+            -(grav_english / weight**2) * (thrust - drag) * GRAV_ENGLISH_LBM
         )
-        J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.DRAG] = -(GRAV_ENGLISH_GASP / weight)
+        J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.DRAG] = -(grav_english / weight)
         J[Dynamic.Mission.VELOCITY_RATE, Dynamic.Vehicle.Propulsion.THRUST_TOTAL] = (
-            GRAV_ENGLISH_GASP / weight
+            grav_english / weight
         )