"""Estimation of the profile drag of miscellaneous items."""
# This file is part of FAST-OAD_CS23 : A framework for rapid Overall Aircraft Design
# Copyright (C) 2022 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 fastoad.api as oad
from openmdao.core.explicitcomponent import ExplicitComponent
from ..constants import SUBMODEL_CD0_OTHER
[docs]@oad.RegisterSubmodel(SUBMODEL_CD0_OTHER, "fastga.submodel.aerodynamics.other.cd0.legacy")
class Cd0Other(ExplicitComponent):
"""
Profile drag estimation for miscellaneous items such as cowling, cooling and various component
Based on : Gudmundsson, Snorri. General aviation aircraft design: Applied Methods and
Procedures. Butterworth-Heinemann, 2013.
"""
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
self.add_input("data:geometry:propulsion:engine:layout", val=np.nan)
self.add_input("data:geometry:wing:area", val=np.nan, units="m**2")
if self.options["low_speed_aero"]:
# Gudmundsson p715. Assuming cx_cooling*wing area/MTOW value of the book is typical
self.add_input("data:aerodynamics:cooling:low_speed:CD0", val=0.0005525)
self.add_output("data:aerodynamics:other:low_speed:CD0")
self.declare_partials(
of="data:aerodynamics:other:low_speed:CD0",
wrt=["data:geometry:wing:area", "data:aerodynamics:cooling:low_speed:CD0"],
method="exact",
)
else:
# Gudmundsson p715. Assuming cx_cooling*wing area/MTOW value of the book is typical
self.add_input("data:aerodynamics:cooling:cruise:CD0", val=0.0005525)
self.add_output("data:aerodynamics:other:cruise:CD0")
self.declare_partials(
of="data:aerodynamics:other:cruise:CD0",
wrt=["data:geometry:wing:area", "data:aerodynamics:cooling:cruise:CD0"],
method="exact",
)
self.declare_partials("*", "*", method="exact")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
prop_layout = inputs["data:geometry:propulsion:engine:layout"]
wing_area = inputs["data:geometry:wing:area"]
# COWLING (only if engine in fuselage): cx_cowl*wing_area assumed typical (Gudmundsson p739)
if prop_layout == 3.0:
cd0_cowling = 0.0267 / wing_area
else:
cd0_cowling = 0.0
# Cooling (piston engine only)
# Gudmundsson p739. Sum of other components (not calculated here), cx_other*wing_area
# assumed typical
cd0_components = 0.0253 / wing_area
if self.options["low_speed_aero"]:
# FIXME: should come from propulsion model...
cd0_cooling = inputs["data:aerodynamics:cooling:low_speed:CD0"]
outputs["data:aerodynamics:other:low_speed:CD0"] = (
cd0_cowling + cd0_cooling + cd0_components
)
else:
cd0_cooling = inputs["data:aerodynamics:cooling:cruise:CD0"]
outputs["data:aerodynamics:other:cruise:CD0"] = (
cd0_cowling + cd0_cooling + cd0_components
)
[docs] def compute_partials(self, inputs, partials, discrete_inputs=None):
prop_layout = inputs["data:geometry:propulsion:engine:layout"]
wing_area = inputs["data:geometry:wing:area"]
if prop_layout == 3.0:
d_cd0_cowl_d_wing_area = -0.0267 / wing_area**2.0
else:
d_cd0_cowl_d_wing_area = 0.0
if self.options["low_speed_aero"]:
partials[
"data:aerodynamics:other:low_speed:CD0", "data:aerodynamics:cooling:low_speed:CD0"
] = 1.0
partials["data:aerodynamics:other:low_speed:CD0", "data:geometry:wing:area"] = (
d_cd0_cowl_d_wing_area - 0.0253 / wing_area**2.0
)
else:
partials[
"data:aerodynamics:other:cruise:CD0", "data:aerodynamics:cooling:cruise:CD0"
] = 1.0
partials["data:aerodynamics:other:cruise:CD0", "data:geometry:wing:area"] = (
d_cd0_cowl_d_wing_area - 0.0253 / wing_area**2.0
)