OpenMDAO · xjjiang · Jun 9, 2026 · Jun 9, 2026 · Jun 9, 2026 · Jun 11, 2026
diff --git a/aviary/interface/test/sizing_results_for_test.json b/aviary/interface/test/sizing_results_for_test.json
@@ -1118,6 +1118,12 @@
         "unitless",
         "<class 'int'>"
     ],
+    [
+        "aircraft:design:percent_excrescence_drag",
+        0.06,
+        "unitless",
+        "<class 'float'>"
+    ],
     [
         "mission:gross_mass",
         175400.0,

diff --git a/aviary/mission/test/test_mission_fuel_burn.py b/aviary/mission/test/test_mission_fuel_burn.py
@@ -87,3 +87,7 @@ def test_taxi_in_fuel_burned(self):
 
         assert_near_equal(fuel_burned, 13234.43186723, tol)
         assert_near_equal(block_fuel, 13334.43186723, tol)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/aviary/models/aircraft/blended_wing_body/generic_BWB_GASP.csv b/aviary/models/aircraft/blended_wing_body/generic_BWB_GASP.csv
@@ -153,6 +153,7 @@ aircraft:wing:zero_lift_angle,0,deg
 aircraft:design:cruise_altitude,41000,ft
 aircraft:design:gross_mass,150000,lbm
 aircraft:design:mach,0.8,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3500,NM
 mission:landing:airport_altitude,0,ft
 mission:landing:braking_delay,1,s

diff --git a/aviary/models/aircraft/large_single_aisle_1/large_single_aisle_1_GASP.csv b/aviary/models/aircraft/large_single_aisle_1/large_single_aisle_1_GASP.csv
@@ -140,6 +140,7 @@ aircraft:wing:zero_lift_angle,-1.2,deg
 aircraft:design:cruise_altitude,37500,ft
 aircraft:design:gross_mass,175400,lbm
 aircraft:design:mach,0.8,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3675,NM
 mission:landing:airport_altitude,0,ft
 mission:landing:braking_delay,1,s

diff --git a/aviary/models/aircraft/large_turboprop_freighter/large_turboprop_freighter_GASP.csv b/aviary/models/aircraft/large_turboprop_freighter/large_turboprop_freighter_GASP.csv
@@ -191,6 +191,7 @@ aircraft:furnishings:mass, 0, lbm
 aircraft:design:cruise_altitude, 21000, ft
 aircraft:design:gross_mass, 155000, lbm
 aircraft:design:mach, 0.475, unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range, 2020, NM
 
 # Takeoff and Landing

diff --git a/aviary/models/aircraft/small_single_aisle/small_single_aisle_GASP.csv b/aviary/models/aircraft/small_single_aisle/small_single_aisle_GASP.csv
@@ -139,6 +139,7 @@ aircraft:wing:zero_lift_angle,-1.2,deg
 aircraft:design:cruise_altitude,37000,ft
 aircraft:design:gross_mass,124780,lbm
 aircraft:design:mach,0.78,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3480,NM
 mission:landing:airport_altitude,0,ft
 mission:landing:braking_delay,1,s

diff --git a/aviary/subsystems/aerodynamics/aerodynamics_builder.py b/aviary/subsystems/aerodynamics/aerodynamics_builder.py
@@ -796,6 +796,7 @@ def report(self, prob, reports_folder, **kwargs):
     # Mission.GROSS_MASS,
     Aircraft.Design.LIFT_COEFFICIENT,
     Aircraft.Design.MACH,
+    Aircraft.Design.PERCENT_EXCRESCENCE_DRAG,
 ]
 
 COMPUTED_CORE_INPUTS_BWB = [
@@ -827,6 +828,7 @@ def report(self, prob, reports_folder, **kwargs):
     # Mission.GROSS_MASS,
     Aircraft.Design.LIFT_COEFFICIENT,
     Aircraft.Design.MACH,
+    Aircraft.Design.PERCENT_EXCRESCENCE_DRAG,
 ]
 
 HORIZONTAL_TAIL_INPUTS = [

diff --git a/aviary/subsystems/aerodynamics/flops_based/computed_aero_group.py b/aviary/subsystems/aerodynamics/flops_based/computed_aero_group.py
@@ -144,6 +144,7 @@ def setup(self):
                 'laminar_fractions_upper',
                 'laminar_fractions_lower',
                 Aircraft.Wing.AREA,
+                Aircraft.Design.PERCENT_EXCRESCENCE_DRAG,
             ],
         )
 

diff --git a/aviary/subsystems/aerodynamics/flops_based/skin_friction_drag.py b/aviary/subsystems/aerodynamics/flops_based/skin_friction_drag.py
@@ -39,13 +39,6 @@ def initialize(self):
         add_aviary_option(self, Aircraft.VerticalTail.NUM_TAILS)
         add_aviary_option(self, Aircraft.Wing.AIRFOIL_TECHNOLOGY)
 
-        # TODO: Bring this into the variable hierarchy.
-        self.options.declare(
-            'excrescences_drag',
-            default=0.06,
-            desc='Drag contribution of excrescences as a percentage.',
-        )
-
     def setup(self):
         nn = self.options['num_nodes']
 
@@ -85,6 +78,11 @@ def setup(self):
             units=get_units(Aircraft.Wing.LAMINAR_FLOW_LOWER),
             desc='Vector of component lower-surface laminar-flow fractions.',
         )
+        add_aviary_input(
+            self,
+            Aircraft.Design.PERCENT_EXCRESCENCE_DRAG,
+            desc='Drag contribution of excrescences as a percentage.',
+        )
 
         # Aircraft design inputs
         add_aviary_input(self, Aircraft.Wing.AREA, units='ft**2')
@@ -102,7 +100,10 @@ def setup_partials(self):
         nc = self.nc
         n = nn * nc
 
-        self.declare_partials(of='skin_friction_drag_coeff', wrt=[Aircraft.Wing.AREA])
+        self.declare_partials(
+            of='skin_friction_drag_coeff',
+            wrt=[Aircraft.Wing.AREA, Aircraft.Design.PERCENT_EXCRESCENCE_DRAG],
+        )
 
         rows = np.repeat(np.arange(nn), nc)
         cols = np.tile(np.arange(nc), nn)
@@ -177,14 +178,14 @@ def compute(self, inputs, outputs):
 
         # Add drag for excrescences.
 
-        # TODO - Per component not completely implemented in aviary 1.0
+        # See issue #1184 - Per component not completely implemented in aviary 1.0
         # Var mission_skin_friction_drag_corrections_count is a vector over components and is added
         # to the drag.
         # This may be "dead weight" from FLOPS - D.J.
 
-        # An additional six percent of the skin friction drag is added to for excrescences
+        # An additional percentage of the skin friction drag is added to for excrescences
         # (miscellaneous).
-        CDF *= 1.0 + self.options['excrescences_drag']
+        CDF *= 1.0 + inputs[Aircraft.Design.PERCENT_EXCRESCENCE_DRAG]
 
         outputs['skin_friction_drag_coeff'] = CDF
 
@@ -255,10 +256,10 @@ def compute_partials(self, inputs, partials):
         dform_dfine[idx_surf] = dFF1 * (2.0 - airfoil) + dFF2 * (airfoil - 1.0)
 
         den = 1.0 / mission_wing_area
-        CDF = np.einsum('j,ij,j->i', wetted_area, cf, form_factor) * den
+        CDF = CDF0 = np.einsum('j,ij,j->i', wetted_area, cf, form_factor) * den
 
-        excr = 1.0 + self.options['excrescences_drag']
-        CDF *= excr
+        excr = 1.0 + inputs[Aircraft.Design.PERCENT_EXCRESCENCE_DRAG]
+        CDF = CDF * excr
         DCDF_dwet = excr * np.einsum('ij,j->ij', cf, form_factor) * den
         DCDF_dcf = excr * wetted_area * form_factor * den
         DCDF_dform = excr * np.einsum('j,ij->ij', wetted_area, cf) * den
@@ -288,6 +289,10 @@ def compute_partials(self, inputs, partials):
 
         partials['skin_friction_drag_coeff', Aircraft.Wing.AREA] = DCDF_dmwa.ravel()
 
+        partials['skin_friction_drag_coeff', Aircraft.Design.PERCENT_EXCRESCENCE_DRAG] = (
+            CDF0.ravel()
+        )
+
 
 def _calc_laminar_flow(lam):
     return lam * (0.0064164 + lam * (0.48087e-4 - 0.12234e-6 * lam))

diff --git a/aviary/subsystems/aerodynamics/flops_based/test/test_computed_aero_group.py b/aviary/subsystems/aerodynamics/flops_based/test/test_computed_aero_group.py
@@ -504,4 +504,4 @@ def test_large_single_aisle_2_drag(self):
 if __name__ == '__main__':
     unittest.main()
     # test = MissionDragTest()
-    # test.test_large_single_aisle_2_drag()
+    # test.test_basic_large_single_aisle_1()
diff --git a/aviary/subsystems/aerodynamics/flops_based/test/test_skinfriction_drag.py b/aviary/subsystems/aerodynamics/flops_based/test/test_skinfriction_drag.py
@@ -11,7 +11,7 @@
 
 @use_tempdirs
 class SkinFrictionDragTest(unittest.TestCase):
-    def test_derivs(self):
+    def test_case(self):
         nn = 2
 
         fine = np.array([0.13, 0.125, 0.1195, 10.0392, 1.5491, 1.5491])
@@ -42,7 +42,7 @@ def test_derivs(self):
         model.add_subsystem(
             'CDf',
             SkinFrictionDrag(num_nodes=nn, **options),
-            promotes_inputs=[Aircraft.Wing.AREA],
+            promotes_inputs=[Aircraft.Wing.AREA, Aircraft.Design.PERCENT_EXCRESCENCE_DRAG],
             promotes_outputs=['skin_friction_drag_coeff'],
         )
 
@@ -55,6 +55,8 @@ def test_derivs(self):
         prob.set_val('CDf.laminar_fractions_upper', lam_up)
         prob.set_val('CDf.laminar_fractions_lower', lam_low)
         prob.set_val(Aircraft.Wing.AREA, 198.0)
+        # this must be hardcoded because the FLOPS EDET default is normally applied by the preprocessor
+        prob.set_val(Aircraft.Design.PERCENT_EXCRESCENCE_DRAG, 0.06)
 
         prob.run_model()
 
@@ -65,7 +67,7 @@ def test_derivs(self):
 
         assert_near_equal(prob.get_val('skin_friction_drag_coeff'), [14.91229, 15.01284], 1e-6)
 
-    def test_derivs_multiengine(self):
+    def test_case_multiengine(self):
         nn = 2
 
         fine = np.array([0.13, 0.125, 0.1195, 10.0392, 1.5491, 1.5491, 1.125, 1.125, 1.125, 1.125])
@@ -125,7 +127,7 @@ def test_derivs_multiengine(self):
         model.add_subsystem(
             'CDf',
             SkinFrictionDrag(num_nodes=nn, **options),
-            promotes_inputs=[Aircraft.Wing.AREA],
+            promotes_inputs=[Aircraft.Wing.AREA, Aircraft.Design.PERCENT_EXCRESCENCE_DRAG],
             promotes_outputs=['skin_friction_drag_coeff'],
         )
 
@@ -138,6 +140,8 @@ def test_derivs_multiengine(self):
         prob.set_val('CDf.laminar_fractions_upper', lam_up)
         prob.set_val('CDf.laminar_fractions_lower', lam_low)
         prob.set_val(Aircraft.Wing.AREA, 198.0)
+        # this must be hardcoded because the FLOPS EDET default is normally applied by the preprocessor
+        prob.set_val(Aircraft.Design.PERCENT_EXCRESCENCE_DRAG, 0.06)
 
         prob.run_model()
 

diff --git a/aviary/subsystems/mass/mass_builder.py b/aviary/subsystems/mass/mass_builder.py
@@ -163,7 +163,7 @@ def report(self, prob, reports_folder, **kwargs):
 
             # OTHER STRUCTURES (NOT IN GROUP) #
             val, units = find_variable_in_problem(Aircraft.Nacelle.MASS, prob, self.meta_data)
-            f.write(f'|Nacelles|{np.dot(val, num_engines)[0]}||\n')
+            f.write(f'|Nacelles|{np.dot(val, num_engines)}||\n')
             for i, engine in enumerate(engine_models):
                 if isinstance(val, (np.ndarray, list, tuple)):
                     val = val[i]

diff --git a/aviary/utils/legacy_code_data/gasp_defaults.py b/aviary/utils/legacy_code_data/gasp_defaults.py
@@ -137,6 +137,7 @@
         'INGASP.YWFOLD': (0.0, 'ft'),
         'INGASP.UM': (0.02, 'unitless'),
         'INGASP.MUB': (0.4, 'unitless'),
+        'INGASP.PCT_EXCR': (0.075, 'unitless'),
     }
 )
 

diff --git a/aviary/utils/preprocessors.py b/aviary/utils/preprocessors.py
@@ -47,6 +47,13 @@ def preprocess_options(
             verbosity = meta_data[Settings.VERBOSITY]['default_value']
             aviary_options.set_val(Settings.VERBOSITY, verbosity)
 
+    if Settings.AERODYNAMICS_METHOD in aviary_options:
+        aero_method = aviary_options.get_val(Settings.AERODYNAMICS_METHOD)
+    else:
+        raise UserWarning(
+            'AERODYNAMICS_METHOD not specified. Cannot preprocess fuel aerodynamic inputs.'
+        )
+
     preprocess_crewpayload(aviary_options, meta_data, verbosity)
     preprocess_fuel_capacities(aviary_options, verbosity)
 
@@ -82,6 +89,13 @@ def preprocess_options(
                         f'Aircraft.Wing.THICKNESS_TO_CHORD ({tc}).'
                     )
 
+    if Aircraft.Design.PERCENT_EXCRESCENCE_DRAG not in aviary_options:
+        # In FLOPS, excrescence drag percentage is not able to be set via the input file
+        # Therefore, it appears to have been hardcoded into the method
+        # Here we set the default value to that fixed value
+        if aviary_options.get_val(Settings.AERODYNAMICS_METHOD) is LegacyCode.FLOPS:
+            aviary_options.set_val(Aircraft.Design.PERCENT_EXCRESCENCE_DRAG, 0.06)
+
 
 def preprocess_crewpayload(aviary_options: AviaryValues, meta_data=CoreMetaData, verbosity=None):
     """

diff --git a/aviary/utils/test/data/converter_test_BWB_GASP.csv b/aviary/utils/test/data/converter_test_BWB_GASP.csv
@@ -38,6 +38,7 @@ aircraft:design:lift_dependent_drag_coeff_factor,0.85,unitless
 aircraft:design:mach,0.8,unitless
 aircraft:design:max_structural_speed,402.5,mi/h
 aircraft:design:part25_structural_category,3.0,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3500.0,NM
 aircraft:design:static_margin,0.05,unitless
 aircraft:design:structural_mass_increment,0.0,lbm

diff --git a/aviary/utils/test/data/converter_test_configuration_GASP.csv b/aviary/utils/test/data/converter_test_configuration_GASP.csv
@@ -31,6 +31,7 @@ aircraft:design:landing_to_takeoff_mass_ratio,0.9423,unitless
 aircraft:design:mach,0.8,unitless
 aircraft:design:max_structural_speed,440.0,mi/h
 aircraft:design:part25_structural_category,3.0,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3500.0,NM
 aircraft:design:static_margin,0.05,unitless
 aircraft:design:structural_mass_increment,0.0,lbm

diff --git a/aviary/utils/test/data/converter_test_large_single_aisle_1_GASP.csv b/aviary/utils/test/data/converter_test_large_single_aisle_1_GASP.csv
@@ -31,6 +31,7 @@ aircraft:design:landing_to_takeoff_mass_ratio,0.9423,unitless
 aircraft:design:mach,0.8,unitless
 aircraft:design:max_structural_speed,402.5,mi/h
 aircraft:design:part25_structural_category,3.0,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3675.0,NM
 aircraft:design:static_margin,0.03,unitless
 aircraft:design:structural_mass_increment,0.0,lbm

diff --git a/aviary/utils/test/data/converter_test_small_single_aisle_GASP.csv b/aviary/utils/test/data/converter_test_small_single_aisle_GASP.csv
@@ -31,6 +31,7 @@ aircraft:design:landing_to_takeoff_mass_ratio,0.9423,unitless
 aircraft:design:mach,0.78,unitless
 aircraft:design:max_structural_speed,402.5,mi/h
 aircraft:design:part25_structural_category,3.0,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3480.0,NM
 aircraft:design:static_margin,0.05,unitless
 aircraft:design:structural_mass_increment,0.0,lbm

diff --git a/aviary/validation_cases/validation_data/test_data/bwb_detailed_FLOPS_data.py b/aviary/validation_cases/validation_data/test_data/bwb_detailed_FLOPS_data.py
@@ -290,6 +290,7 @@
 # ---------------------------
 inputs.set_val(Settings.EQUATIONS_OF_MOTION, EquationsOfMotion.ENERGY_STATE)
 inputs.set_val(Settings.MASS_METHOD, LegacyCode.FLOPS)
+inputs.set_val(Settings.AERODYNAMICS_METHOD, LegacyCode.FLOPS)
 
 # ---------------------------
 #          OUTPUTS

diff --git a/aviary/validation_cases/validation_data/test_data/bwb_simple_FLOPS_data.py b/aviary/validation_cases/validation_data/test_data/bwb_simple_FLOPS_data.py
@@ -239,6 +239,7 @@
 # ---------------------------
 inputs.set_val(Settings.EQUATIONS_OF_MOTION, EquationsOfMotion.ENERGY_STATE)
 inputs.set_val(Settings.MASS_METHOD, LegacyCode.FLOPS)
+inputs.set_val(Settings.AERODYNAMICS_METHOD, LegacyCode.FLOPS)
 
 # ---------------------------
 #          OUTPUTS

diff --git a/aviary/validation_cases/validation_data/test_data/large_single_aisle_1_FLOPS_data.py b/aviary/validation_cases/validation_data/test_data/large_single_aisle_1_FLOPS_data.py
@@ -248,6 +248,7 @@
 # ---------------------------
 inputs.set_val(Settings.EQUATIONS_OF_MOTION, EquationsOfMotion.ENERGY_STATE)
 inputs.set_val(Settings.MASS_METHOD, LegacyCode.FLOPS)
+inputs.set_val(Settings.AERODYNAMICS_METHOD, LegacyCode.FLOPS)
 
 # ---------------------------
 #          OUTPUTS

diff --git a/aviary/validation_cases/validation_data/test_models/aircraft_for_bench_GwGm.csv b/aviary/validation_cases/validation_data/test_models/aircraft_for_bench_GwGm.csv
@@ -143,6 +143,7 @@ aircraft:wing:zero_lift_angle,-1.2,deg
 aircraft:design:cruise_altitude,37500,ft
 aircraft:design:gross_mass,175400,lbm
 aircraft:design:mach,0.8,unitless
+aircraft:design:percent_excrescence_drag,0.075,unitless
 aircraft:design:range,3675,NM
 mission:landing:airport_altitude,0,ft
 mission:landing:braking_delay,1,s