diff --git a/aviary/variable_info/variable_meta_data.py b/aviary/variable_info/variable_meta_data.py
index f61783840..af25ed5b6 100644
--- a/aviary/variable_info/variable_meta_data.py
+++ b/aviary/variable_info/variable_meta_data.py
@@ -418,7 +418,7 @@
     },
     units='unitless',
     desc='canard theoretical aspect ratio',
-    default_value=None,
+    default_value=0.0,  # changed from None
 )
 
 add_meta_data(
@@ -434,6 +434,7 @@
     },
     units='ft',
     desc='Reynolds characteristic length for the canard',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -449,6 +450,7 @@
     },
     units='unitless',
     desc='canard fineness ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -553,7 +555,7 @@
     },
     units='ft**2',
     desc='canard wetted area',
-    default_value=None,
+    default_value=0.0,  # changed from None
 )
 
 add_meta_data(
@@ -1253,7 +1255,7 @@
 
 add_meta_data(
     # Note users must enable this feature, or the associated calculation is
-    # discarded
+    # discarded. Default to 0.0
     Aircraft.Design.EMPTY_MASS_MARGIN_SCALER,
     meta_data=_MetaData,
     historical_name={
@@ -1263,7 +1265,7 @@
     },
     units='unitless',
     desc='empty mass margin scaler',
-    default_value=0.0,  # Note: not 1.0 here
+    default_value=0.0,
 )
 
 add_meta_data(
@@ -1716,6 +1718,7 @@
     historical_name={"GASP": 'INGASP.LCABLE', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='length of cable for hybrid electric augmented system',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -2160,7 +2163,7 @@
     historical_name={"GASP": 'INGASP.DIAM_REF', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='engine reference diameter',
-    default_value=0.0,
+    default_value=0.0,  # In geometry/gasp_based/engine.py, it was 5.8
 )
 
 # NOTE This unscaled turbine (engine) weight is an input provided by the user, and is not
@@ -2367,6 +2370,7 @@
     units='unitless',
     desc='Engine wing mount locations as fractions of semispan; (NUM_WING_ENGINES)/2 values '
     'are input',
+    # In mass/gasp_based/fixed.py and geometry/gasp_based/electric.py, default was [0.35]
     default_value=np.array([0.0]),
 )
 
@@ -2887,6 +2891,8 @@
     historical_name={"GASP": 'INGASP.SKWF', "FLOPS": None, "LEAPS1": None},
     units='unitless',
     desc='fraction of total theoretical wing volume used for wing fuel',
+    # added. In geometry/gasp_based/wing.py, it was 0.6. In /mass/gasp_based/equipment_and_useful_load.py, it was 0.5.
+    default_value=0.0,
 )
 
 add_meta_data(
@@ -2969,6 +2975,7 @@
     historical_name={"GASP": 'INGASP.FVOLW_GEOM', "FLOPS": None, "LEAPS1": None},
     units='ft**3',
     desc='wing tank fuel volume based on geometry',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3065,7 +3072,7 @@
     },
     units='ft',
     desc='average fuselage diameter',
-    default_value=0.0,  # added
+    default_value=0.0,  # added. In several components, it was set to 10 or 13.1.
 )
 
 add_meta_data(
@@ -3081,6 +3088,7 @@
     },
     units='ft',
     desc='Reynolds characteristic length for the fuselage',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3101,7 +3109,7 @@
     historical_name={"GASP": 'INGASP.HCK', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='mean fuselage cabin diameter minus mean fuselage nose diameter',
-    default_value=4.5,
+    default_value=0.0,  # In geometry/gasp_based/fuselage.py, it was 4.5.
 )
 
 add_meta_data(
@@ -3114,6 +3122,7 @@
     },
     units='unitless',
     desc='fuselage diameter to wing span ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3129,6 +3138,7 @@
     },
     units='unitless',
     desc='fuselage fineness ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3197,7 +3207,7 @@
     desc='Define the Fuselage total length. If total_length is not input for a '
     'passenger transport, LEAPS will calculate the fuselage length, width and '
     'depth and the length of the passenger compartment.',
-    default_value=0.0,
+    default_value=0.0,  # in several components, it was set to 129.4 or 200.
 )
 
 add_meta_data(
@@ -3210,6 +3220,7 @@
     },
     units='unitless',
     desc='fuselage length to diameter ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3381,6 +3392,7 @@
     historical_name={"GASP": 'INGASP.ELPC', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='length of the pilot compartment',
+    default_value=0.0,  # added. # In geometry/gasp_based/fuselage.py, it was 9.5
 )
 
 add_meta_data(
@@ -3502,7 +3514,7 @@
     },
     units='unitless',
     desc='horizontal tail theoretical aspect ratio',
-    default_value=None,
+    default_value=4.75,  # changed from None
 )
 
 add_meta_data(
@@ -3526,6 +3538,7 @@
     },
     units='ft',
     desc='Reynolds characteristic length for the horizontal tail',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3541,6 +3554,7 @@
     },
     units='unitless',
     desc='horizontal tail fineness ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3676,7 +3690,8 @@
     },
     units='unitless',
     desc='horizontal tail theoretical taper ratio',
-    default_value=None,
+    # In geometry/flops_based/prep_geom.py and mass/gasp_based/empennage.py, it was 0.352.
+    default_value=0.0,  # changed from None.
 )
 
 add_meta_data(
@@ -3706,7 +3721,7 @@
     'tail is mounted. Defaults: 0.0 == for body mounted (default for '
     'transport with all engines on wing); 1.0 == for T tail '
     '(default for transport with multiple engines on fuselage)',
-    default_value=None,
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -3821,7 +3836,7 @@
     },
     units='psi',
     desc='hydraulic system pressure',
-    default_value=0.0,
+    default_value=0.0,  # changed from 3000.0
 )
 
 #
@@ -4121,6 +4136,7 @@
     },
     units='ft',
     desc='Reynolds characteristic length for nacelle for each engine model',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4138,7 +4154,7 @@
     historical_name={"GASP": 'INGASP.DNQDE', "FLOPS": None, "LEAPS1": None},
     units="unitless",
     desc='ratio of nacelle diameter to engine core diameter',
-    default_value=1.25,
+    default_value=1.25,  # In geometry/gasp_based/engine.py, it was 1.25
 )
 
 add_meta_data(
@@ -4154,6 +4170,7 @@
     },
     units='unitless',
     desc='nacelle fineness ratio',
+    default_value=0.0,  # added. # In geometry/gasp_based/engine.py, it was 2.
 )
 
 add_meta_data(
@@ -4251,6 +4268,7 @@
     },
     units='ft**2',
     desc='total nacelles wetted area',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4266,6 +4284,7 @@
     },
     units='ft**2',
     desc='wetted area of a single nacelle for each engine model',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4528,6 +4547,7 @@
     historical_name={"GASP": 'INGASP.SSTQSW', "FLOPS": None, "LEAPS1": None},
     units='unitless',
     desc='ratio of strut area to wing area',
+    default_value=0.0,  # added. In geometry/gasp_based/strut.py, it was set to .2.
 )
 
 add_meta_data(
@@ -4540,6 +4560,7 @@
     },
     units='ft',
     desc='attachment location of strut the full attachment-to-attachment span',
+    default_value=0.0,  # added
 )
 
 # related to Aircraft.Strut.ATTACHMENT_LOCATION
@@ -4549,6 +4570,7 @@
     historical_name={"GASP": None, "FLOPS": None, "LEAPS1": None},
     units='unitless',
     desc='attachment location of strut as fraction of the half-span',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4557,6 +4579,7 @@
     historical_name={"GASP": 'INGASP.STRTCHD', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='chord of the strut',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4674,7 +4697,7 @@
     },
     units='unitless',
     desc='vertical tail theoretical aspect ratio',
-    default_value=None,
+    default_value=0.0,  # changed from None
 )
 
 add_meta_data(
@@ -4698,6 +4721,7 @@
     },
     units='ft',
     desc='Reynolds characteristic length for the vertical tail',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4713,6 +4737,7 @@
     },
     units='unitless',
     desc='vertical tail fineness ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -4906,7 +4931,7 @@
     },
     units='ft**2',
     desc='vertical tails wetted area',
-    default_value=None,
+    default_value=0.0,  # changed from None
 )
 
 add_meta_data(
@@ -4996,7 +5021,7 @@
     },
     units='ft**2',
     desc='reference wing area',
-    default_value=0.0,
+    default_value=0.0,  # In several components, it was set to 100, 150, 200, 1370.3 etc.
 )
 
 add_meta_data(
@@ -5022,7 +5047,7 @@
     },
     units='unitless',
     desc='ratio of the wing span to its mean chord',
-    default_value=0.0,
+    default_value=0.0,  # in several components, it was 1 or 10.13.
 )
 
 add_meta_data(
@@ -5044,6 +5069,7 @@
     historical_name={"GASP": 'INGASP.CBARW', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='mean aerodynamic chord of the wing',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -5055,7 +5081,8 @@
         "LEAPS1": 'aircraft.outputs.L0_wing.bending_material_factor',
     },
     units='unitless',
-    desc='Wing bending material factor with sweep adjustment. Used to compute',
+    desc='Wing bending material factor with sweep adjustment. Used to compute ',
+    'Aircraft.Wing.BENDING_MATERIAL_MASS',
     default_value=0.0,  # added
 )
 
@@ -5121,6 +5148,7 @@
     historical_name={"GASP": 'INGASP.CRCLW', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='wing chord at fuselage centerline',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -5145,6 +5173,7 @@
     },
     units='ft',
     desc='Reynolds characteristic length for the wing',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -5279,6 +5308,7 @@
     },
     units='unitless',
     desc='wing fineness ratio',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -5380,7 +5410,8 @@
     historical_name={"GASP": 'INGASP.YWFOLD', "FLOPS": None, "LEAPS1": None},
     units='ft',
     desc='folded wingspan',
-    default_value=118,
+    # In geometry/gasp_based/non_dimensional_conversion.py and geometry/gasp_based/wing.py, it was 25.
+    default_value=0,  # changed from 118
 )
 
 add_meta_data(
@@ -5539,6 +5570,7 @@
     historical_name={"GASP": 'INGASP.SWPLE', "FLOPS": None, "LEAPS1": None},
     units='rad',
     desc='sweep angle at leading edge of wing',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -5593,6 +5625,7 @@
     },
     units='lbf/ft**2',
     desc='wing loading',
+    default_value=0.0,  # added. In several components, it was 128.
 )
 
 add_meta_data(
@@ -5809,6 +5842,7 @@
     },
     units='ft',
     desc='wing chord length at wing root',
+    default_value=0.0,  # added
 )
 
 add_meta_data(
@@ -5884,6 +5918,7 @@
     },
     units='ft',
     desc='span of main wing',
+    # in several components, it was set to 128, or 117.8 but there are other values.
     default_value=0.0,
 )
 
@@ -5998,7 +6033,8 @@
     },
     units='deg',
     desc='quarter-chord sweep angle of the wing',
-    default_value=0.0,  # TODO required
+    # In several components, it was 0.436 (rad) or 25 (deg).
+    default_value=0.0,  # TODO required.
 )
 
 add_meta_data(
@@ -6023,7 +6059,7 @@
     },
     units='unitless',
     desc='taper ratio of the wing',
-    default_value=0.0,  # TODO required
+    default_value=0.0,  # TODO required. In several components, it was .33.
 )
 
 add_meta_data(
@@ -6084,6 +6120,7 @@
     historical_name={"GASP": 'INGASP.TCR', "FLOPS": None, "LEAPS1": None},
     units='unitless',
     desc='thickness-to-chord ratio at the root of the wing',
+    default_value=0.0,  # added. In several components, it was 0.11 or 0.15.
 )
 
 add_meta_data(
@@ -6092,6 +6129,7 @@
     historical_name={"GASP": 'INGASP.TCT', "FLOPS": None, "LEAPS1": None},
     units='unitless',
     desc='thickness-to-chord ratio at the tip of the wing',
+    default_value=0.0,  # added. In geometry/gasp_based/wing.py, it was 0.1
 )
 
 add_meta_data(
@@ -6100,6 +6138,7 @@
     historical_name={"GASP": 'INGASP.TC', "FLOPS": None, "LEAPS1": None},
     units='unitless',
     desc='wing thickness-chord ratio at the wing station of the mean aerodynamic chord',
+    default_value=0.0,  # added. In geometry/gasp_based/wing.py, it was 0.1.
 )
 
 add_meta_data(
@@ -6147,7 +6186,7 @@
     },
     units='ft**2',
     desc='wing wetted area',
-    default_value=None,
+    default_value=0.0,  # changed from None
 )
 
 add_meta_data(
@@ -6782,7 +6821,8 @@
     },
     units='lbm',
     desc='design gross mass of the aircraft',
-    default_value=0.0,  # changed from None
+    # changed form None. In several components, it was set to 20000, 152000 or 175400.
+    default_value=0.0,
 )
 
 add_meta_data(