# 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_CL_ALPHA_DOT
[docs]@oad.RegisterSubmodel(
SUBMODEL_CL_ALPHA_DOT, "fastga.submodel.aerodynamics.aircraft.cl_rate_of_aoa_change.legacy"
)
class ComputeCLAlphaDotAircraft(om.ExplicitComponent):
"""
Computation of the increase in lift due to a rate of change of AoA. Not destined for the
computation of the equilibrium since they are assumed quasi-steady but rather for future
interface with flight simulator.The convention from :cite:`roskampart6:1985` are used,
meaning that, for the derivative with respect to a rate of AOA, this rate is made
dimensionless by multiplying it by the MAC and dividing it by 2 times the airspeed.
Based on :cite:`roskampart6:1985` section 10.2.3
"""
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
self.add_input("data:geometry:wing:area", units="m**2", val=np.nan)
self.add_input("data:geometry:horizontal_tail:area", units="m**2", val=np.nan)
self.add_input("data:geometry:horizontal_tail:volume_coefficient", val=np.nan)
self.add_input("data:aerodynamics:horizontal_tail:efficiency", val=np.nan)
if self.options["low_speed_aero"]:
self.add_input(
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient", val=np.nan
)
self.add_input(
"data:aerodynamics:horizontal_tail:low_speed:CL_alpha", val=np.nan, units="rad**-1"
)
self.add_output("data:aerodynamics:aircraft:low_speed:CL_alpha_dot", units="rad**-1")
self.declare_partials(
of="data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
wrt=[
"data:geometry:wing:area",
"data:geometry:horizontal_tail:area",
"data:geometry:horizontal_tail:volume_coefficient",
"data:aerodynamics:horizontal_tail:low_speed:CL_alpha",
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient",
"data:aerodynamics:horizontal_tail:efficiency",
],
method="exact",
)
else:
self.add_input("data:aerodynamics:horizontal_tail:cruise:downwash_gradient", val=np.nan)
self.add_input(
"data:aerodynamics:horizontal_tail:cruise:CL_alpha", val=np.nan, units="rad**-1"
)
self.add_output("data:aerodynamics:aircraft:cruise:CL_alpha_dot", units="rad**-1")
self.declare_partials(
of="data:aerodynamics:aircraft:cruise:CL_alpha_dot",
wrt=[
"data:geometry:wing:area",
"data:geometry:horizontal_tail:area",
"data:geometry:horizontal_tail:volume_coefficient",
"data:aerodynamics:horizontal_tail:cruise:CL_alpha",
"data:aerodynamics:horizontal_tail:cruise:downwash_gradient",
"data:aerodynamics:horizontal_tail:efficiency",
],
method="exact",
)
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
eta_h = inputs["data:aerodynamics:horizontal_tail:efficiency"]
volume_coeff_ht = inputs["data:geometry:horizontal_tail:volume_coefficient"]
# From the instructions section 10.2.3, it seems to suggest that we need the lift curve
# coefficient with respect to the area of the horizontal tail hence the change in
# reference surface. This seems to be confirmed by the order of magnitude of the results
wing_area = inputs["data:geometry:wing:area"]
ht_area = inputs["data:geometry:horizontal_tail:area"]
if self.options["low_speed_aero"]:
cl_alpha_ht = inputs["data:aerodynamics:horizontal_tail:low_speed:CL_alpha"]
downwash_gradient = inputs[
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient"
]
outputs["data:aerodynamics:aircraft:low_speed:CL_alpha_dot"] = (
2.0
* cl_alpha_ht
* eta_h
* volume_coeff_ht
* downwash_gradient
* wing_area
/ ht_area
)
else:
cl_alpha_ht = inputs["data:aerodynamics:horizontal_tail:cruise:CL_alpha"]
downwash_gradient = inputs["data:aerodynamics:horizontal_tail:cruise:downwash_gradient"]
outputs["data:aerodynamics:aircraft:cruise:CL_alpha_dot"] = (
2.0
* cl_alpha_ht
* eta_h
* volume_coeff_ht
* downwash_gradient
* wing_area
/ ht_area
)
[docs] def compute_partials(self, inputs, partials, discrete_inputs=None):
eta_h = inputs["data:aerodynamics:horizontal_tail:efficiency"]
volume_coeff_ht = inputs["data:geometry:horizontal_tail:volume_coefficient"]
wing_area = inputs["data:geometry:wing:area"]
ht_area = inputs["data:geometry:horizontal_tail:area"]
if self.options["low_speed_aero"]:
cl_alpha_ht = inputs["data:aerodynamics:horizontal_tail:low_speed:CL_alpha"]
downwash_gradient = inputs[
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient"
]
partials[
"data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
"data:aerodynamics:horizontal_tail:efficiency",
] = 2.0 * cl_alpha_ht * volume_coeff_ht * downwash_gradient * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
"data:geometry:horizontal_tail:volume_coefficient",
] = 2.0 * cl_alpha_ht * eta_h * downwash_gradient * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
"data:aerodynamics:horizontal_tail:low_speed:CL_alpha",
] = 2.0 * volume_coeff_ht * eta_h * downwash_gradient * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
"data:aerodynamics:horizontal_tail:low_speed:downwash_gradient",
] = 2.0 * volume_coeff_ht * eta_h * cl_alpha_ht * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
"data:geometry:wing:area",
] = 2.0 * volume_coeff_ht * eta_h * cl_alpha_ht * downwash_gradient / ht_area
partials[
"data:aerodynamics:aircraft:low_speed:CL_alpha_dot",
"data:geometry:horizontal_tail:area",
] = (
-2.0
* volume_coeff_ht
* eta_h
* cl_alpha_ht
* downwash_gradient
* wing_area
/ ht_area**2.0
)
else:
cl_alpha_ht = inputs["data:aerodynamics:horizontal_tail:cruise:CL_alpha"]
downwash_gradient = inputs["data:aerodynamics:horizontal_tail:cruise:downwash_gradient"]
partials[
"data:aerodynamics:aircraft:cruise:CL_alpha_dot",
"data:aerodynamics:horizontal_tail:efficiency",
] = 2.0 * cl_alpha_ht * volume_coeff_ht * downwash_gradient * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:cruise:CL_alpha_dot",
"data:geometry:horizontal_tail:volume_coefficient",
] = 2.0 * cl_alpha_ht * eta_h * downwash_gradient * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:cruise:CL_alpha_dot",
"data:aerodynamics:horizontal_tail:cruise:CL_alpha",
] = 2.0 * volume_coeff_ht * eta_h * downwash_gradient * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:cruise:CL_alpha_dot",
"data:aerodynamics:horizontal_tail:cruise:downwash_gradient",
] = 2.0 * volume_coeff_ht * eta_h * cl_alpha_ht * wing_area / ht_area
partials[
"data:aerodynamics:aircraft:cruise:CL_alpha_dot",
"data:geometry:wing:area",
] = 2.0 * volume_coeff_ht * eta_h * cl_alpha_ht * downwash_gradient / ht_area
partials[
"data:aerodynamics:aircraft:cruise:CL_alpha_dot",
"data:geometry:horizontal_tail:area",
] = (
-2.0
* volume_coeff_ht
* eta_h
* cl_alpha_ht
* downwash_gradient
* wing_area
/ ht_area**2.0
)