"""Estimation of rolling moment du to the ailerons."""
# 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 .figure_digitization import FigureDigitization
from ..constants import SUBMODEL_CL_AILERON
[docs]@oad.RegisterSubmodel(
SUBMODEL_CL_AILERON, "fastga.submodel.aerodynamics.aileron.roll_moment.legacy"
)
class ComputeClDeltaAileron(FigureDigitization):
"""
Roll moment due to aileron deflection estimated based on the methodology presented in
Gudmundsson. This methodology is known to overestimate the coefficient so a correction factor
will be added. This coefficient assumes a symmetrical deflection. The convention from
:cite:`roskampart6:1985` are used, meaning that for lateral derivative, the reference length
is the wing span.
Based on the methodology presented in :cite:`gudmundsson:2013`.
"""
[docs] def initialize(self):
self.options.declare("low_speed_aero", default=False, types=bool)
[docs] def setup(self):
self.add_input("data:geometry:wing:aileron:chord_ratio", val=np.nan)
self.add_input("data:geometry:wing:aileron:span_ratio", val=np.nan)
self.add_input("data:geometry:wing:span", val=np.nan, units="m")
self.add_input("data:geometry:wing:area", val=np.nan, units="m**2")
self.add_input("data:geometry:wing:root:chord", val=np.nan, units="m")
self.add_input("data:geometry:wing:taper_ratio", val=np.nan)
self.add_input(
"settings:aerodynamics:aileron:tip_effect:k_factor",
val=0.9,
desc="Correction coefficient to take into account tip effect when "
"computing the roll authority of the ailerons",
)
if self.options["low_speed_aero"]:
self.add_input("data:aerodynamics:low_speed:mach", val=np.nan)
self.add_output("data:aerodynamics:aileron:low_speed:Cl_delta_a", units="rad**-1")
else:
self.add_input("data:aerodynamics:cruise:mach", val=np.nan)
self.add_output("data:aerodynamics:aileron:cruise:Cl_delta_a", units="rad**-1")
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
wing_span = inputs["data:geometry:wing:span"]
wing_area = inputs["data:geometry:wing:area"]
l2_wing = inputs["data:geometry:wing:root:chord"]
wing_taper_ratio = inputs["data:geometry:wing:taper_ratio"]
aileron_span_ratio = inputs["data:geometry:wing:aileron:span_ratio"]
tip_effect_factor = inputs["settings:aerodynamics:aileron:tip_effect:k_factor"]
if self.options["low_speed_aero"]:
mach = inputs["data:aerodynamics:low_speed:mach"]
else:
mach = inputs["data:aerodynamics:cruise:mach"]
aileron_chord_ratio = inputs["data:geometry:wing:aileron:chord_ratio"]
aileron_outer_span = wing_span / 2.0
aileron_inner_span = wing_span * (1.0 - aileron_span_ratio) / 2.0
# Aileron are most mostly going to be used around delta_a = 0 degree, which is the reason
# why the effectiveness is going to be computed around this deflection
alpha_aileron = self.k_prime_single_slotted(0.0, float(aileron_chord_ratio))
lift_increase_aileron = 2 * np.pi / np.sqrt(1 - mach**2) * alpha_aileron
cl_delta_a = (
lift_increase_aileron
* l2_wing
/ (wing_area * wing_span)
* (
(aileron_outer_span**2.0 - aileron_inner_span**2.0)
+ (4.0 * (wing_taper_ratio - 1.0))
/ (3.0 * wing_span)
* (aileron_outer_span**3.0 - aileron_inner_span**3.0)
)
) * tip_effect_factor
if self.options["low_speed_aero"]:
outputs["data:aerodynamics:aileron:low_speed:Cl_delta_a"] = cl_delta_a
else:
outputs["data:aerodynamics:aileron:cruise:Cl_delta_a"] = cl_delta_a