"""Sum of form drags from aircraft components."""
# This file is part of FAST-OAD : A framework for rapid Overall Aircraft Design
# Copyright (C) 2021 ONERA & ISAE-SUPAERO
# FAST is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
import numpy as np
import openmdao.api as om
from fastoad.module_management.service_registry import RegisterSubmodel
from ..constants import SERVICE_CD0_SUM
[docs]@RegisterSubmodel(SERVICE_CD0_SUM, "fastoad.submodel.aerodynamics.CD0.sum.legacy")
class Cd0Total(om.ExplicitComponent):
"""Computes the sum of form drags from aircraft components."""
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
self.add_input("data:geometry:aircraft:wetted_area", val=np.nan, units="m**2")
if self.options["low_speed_aero"]:
self.add_input("data:aerodynamics:wing:low_speed:CD0", shape_by_conn=True, val=np.nan)
self.add_input(
"data:aerodynamics:fuselage:low_speed:CD0", shape_by_conn=True, val=np.nan
)
self.add_input("data:aerodynamics:horizontal_tail:low_speed:CD0", val=np.nan)
self.add_input("data:aerodynamics:vertical_tail:low_speed:CD0", val=np.nan)
self.add_input("data:aerodynamics:nacelles:low_speed:CD0", val=np.nan)
self.add_input("data:aerodynamics:pylons:low_speed:CD0", val=np.nan)
self.add_output(
"data:aerodynamics:aircraft:low_speed:CD0",
copy_shape="data:aerodynamics:wing:low_speed:CD0",
)
self.add_output(
"data:aerodynamics:aircraft:low_speed:CD0:clean",
copy_shape="data:aerodynamics:wing:low_speed:CD0",
)
self.add_output(
"data:aerodynamics:aircraft:low_speed:CD0:parasitic",
copy_shape="data:aerodynamics:wing:low_speed:CD0",
)
else:
self.add_input("data:aerodynamics:wing:cruise:CD0", shape_by_conn=True, val=np.nan)
self.add_input("data:aerodynamics:fuselage:cruise:CD0", shape_by_conn=True, val=np.nan)
self.add_input("data:aerodynamics:horizontal_tail:cruise:CD0", val=np.nan)
self.add_input("data:aerodynamics:vertical_tail:cruise:CD0", val=np.nan)
self.add_input("data:aerodynamics:nacelles:cruise:CD0", val=np.nan)
self.add_input("data:aerodynamics:pylons:cruise:CD0", val=np.nan)
self.add_output(
"data:aerodynamics:aircraft:cruise:CD0",
copy_shape="data:aerodynamics:wing:cruise:CD0",
)
self.add_output(
"data:aerodynamics:aircraft:cruise:CD0:clean",
copy_shape="data:aerodynamics:wing:cruise:CD0",
)
self.add_output(
"data:aerodynamics:aircraft:cruise:CD0:parasitic",
copy_shape="data:aerodynamics:wing:cruise:CD0",
)
[docs] def setup_partials(self):
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
wet_area_total = inputs["data:geometry:aircraft:wetted_area"]
if self.options["low_speed_aero"]:
cd0_wing = inputs["data:aerodynamics:wing:low_speed:CD0"]
cd0_fus = inputs["data:aerodynamics:fuselage:low_speed:CD0"]
cd0_ht = inputs["data:aerodynamics:horizontal_tail:low_speed:CD0"]
cd0_vt = inputs["data:aerodynamics:vertical_tail:low_speed:CD0"]
cd0_nac = inputs["data:aerodynamics:nacelles:low_speed:CD0"]
cd0_pylon = inputs["data:aerodynamics:pylons:low_speed:CD0"]
else:
cd0_wing = inputs["data:aerodynamics:wing:cruise:CD0"]
cd0_fus = inputs["data:aerodynamics:fuselage:cruise:CD0"]
cd0_ht = inputs["data:aerodynamics:horizontal_tail:cruise:CD0"]
cd0_vt = inputs["data:aerodynamics:vertical_tail:cruise:CD0"]
cd0_nac = inputs["data:aerodynamics:nacelles:cruise:CD0"]
cd0_pylon = inputs["data:aerodynamics:pylons:cruise:CD0"]
k_parasite = (
-2.39 * pow(10, -12) * wet_area_total ** 3
+ 2.58 * pow(10, -8) * wet_area_total ** 2
- 0.89 * pow(10, -4) * wet_area_total
+ 0.163
)
cd0_total_clean = cd0_wing + cd0_fus + cd0_ht + cd0_vt + cd0_nac + cd0_pylon
cd0_total = cd0_total_clean * (1.0 + k_parasite)
if self.options["low_speed_aero"]:
outputs["data:aerodynamics:aircraft:low_speed:CD0"] = cd0_total
outputs["data:aerodynamics:aircraft:low_speed:CD0:clean"] = cd0_total_clean
outputs["data:aerodynamics:aircraft:low_speed:CD0:parasitic"] = (
cd0_total - cd0_total_clean
)
else:
outputs["data:aerodynamics:aircraft:cruise:CD0"] = cd0_total
outputs["data:aerodynamics:aircraft:cruise:CD0:clean"] = cd0_total_clean
outputs["data:aerodynamics:aircraft:cruise:CD0:parasitic"] = cd0_total - cd0_total_clean