# 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 openmdao.api as om
import fastoad.api as oad
from ..constants import (
SUBMODEL_CN_BETA,
SUBMODEL_CN_BETA_VT,
SUBMODEL_CN_BETA_FUSELAGE,
)
[docs]@oad.RegisterSubmodel(SUBMODEL_CN_BETA, "submodel.aerodynamics.aircraft.yawing_moment_beta.legacy")
class ComputeCnBetaAircraft(om.Group):
"""
Computation of the increase in yawing moment due to a sideslip angle. Assumes the coefficient
at aircraft level can be obtained by summing the contribution of the individual components (
fuselage and VT). Wing contribution is negligible up until high angles of attack. The
convention from :cite:`roskampart6:1985` are used, meaning that for lateral derivative,
the reference length is the wing span. Does not take into account the effect
of nacelles or propeller lateral forces.
Based on :cite:`roskampart6:1985` section 10.2.4.1
"""
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
if self.options["low_speed_aero"]:
self.add_subsystem(
"fuselage_contribution",
oad.RegisterSubmodel.get_submodel(SUBMODEL_CN_BETA_FUSELAGE),
promotes=["*"],
)
options = {
"low_speed_aero": self.options["low_speed_aero"],
}
self.add_subsystem(
"vt_contribution",
oad.RegisterSubmodel.get_submodel(SUBMODEL_CN_BETA_VT, options=options),
promotes=["*"],
)
self.add_subsystem(
"sum",
_SumCNBetaContributions(low_speed_aero=self.options["low_speed_aero"]),
promotes=["*"],
)
class _SumCNBetaContributions(om.ExplicitComponent):
"""
Sums the contribution of the various components to the increase in yawing moment due to a
sideslip angle.
"""
def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
def setup(self):
self.add_input("data:aerodynamics:fuselage:Cn_beta", val=np.nan, units="rad**-1")
if self.options["low_speed_aero"]:
self.add_input(
"data:aerodynamics:vertical_tail:low_speed:Cn_beta", val=np.nan, units="rad**-1"
)
self.add_output("data:aerodynamics:aircraft:low_speed:Cn_beta", units="rad**-1")
else:
self.add_input(
"data:aerodynamics:vertical_tail:cruise:Cn_beta", val=np.nan, units="rad**-1"
)
self.add_output("data:aerodynamics:aircraft:cruise:Cn_beta", units="rad**-1")
self.declare_partials(of="*", wrt="*", method="exact")
def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
cy_beta_fus = inputs["data:aerodynamics:fuselage:Cn_beta"]
if self.options["low_speed_aero"]:
outputs["data:aerodynamics:aircraft:low_speed:Cn_beta"] = (
+cy_beta_fus + inputs["data:aerodynamics:vertical_tail:low_speed:Cn_beta"]
)
else:
outputs["data:aerodynamics:aircraft:cruise:Cn_beta"] = (
+cy_beta_fus + inputs["data:aerodynamics:vertical_tail:cruise:Cn_beta"]
)
def compute_partials(self, inputs, partials, discrete_inputs=None):
if self.options["low_speed_aero"]:
partials[
"data:aerodynamics:aircraft:low_speed:Cn_beta",
"data:aerodynamics:fuselage:Cn_beta",
] = 1.0
partials[
"data:aerodynamics:aircraft:low_speed:Cn_beta",
"data:aerodynamics:vertical_tail:low_speed:Cn_beta",
] = 1.0
else:
partials[
"data:aerodynamics:aircraft:cruise:Cn_beta",
"data:aerodynamics:fuselage:Cn_beta",
] = 1.0
partials[
"data:aerodynamics:aircraft:cruise:Cn_beta",
"data:aerodynamics:vertical_tail:cruise:Cn_beta",
] = 1.0