"""Estimation of fuselage pitching moment."""
# 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 fastga.models.aerodynamics.components.figure_digitization import FigureDigitization
from fastga.models.aerodynamics.constants import SUBMODEL_CM_ALPHA_FUSELAGE
[docs]@oad.RegisterSubmodel(
SUBMODEL_CM_ALPHA_FUSELAGE, "fastga.submodel.aerodynamics.fuselage.pitching_moment_alpha.legacy"
)
class ComputeCmAlphaFuselage(FigureDigitization):
"""
Estimation of the fuselage pitching moment using the methodology described in section 16.3.8
of Raymer
Based on : Raymer, Daniel P. "Aircraft design: a conceptual approach (AIAA Education
Series)." Reston, Virginia (2012).
"""
[docs] def setup(self):
self.add_input("data:geometry:wing:MAC:leading_edge:x:local", val=np.nan, units="m")
self.add_input("data:geometry:wing:MAC:length", val=np.nan, units="m")
self.add_input("data:geometry:wing:MAC:at25percent:x", val=np.nan, units="m")
self.add_input("data:geometry:wing:root:virtual_chord", val=np.nan, units="m")
self.add_input("data:geometry:wing:area", val=np.nan, units="m**2")
self.add_input("data:geometry:fuselage:length", val=np.nan, units="m")
self.add_input("data:geometry:fuselage:maximum_width", val=np.nan, units="m")
self.add_output("data:aerodynamics:fuselage:cm_alpha", units="rad**-1")
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
wing_area = inputs["data:geometry:wing:area"]
x_wing = inputs["data:geometry:wing:MAC:at25percent:x"]
x0_wing = inputs["data:geometry:wing:MAC:leading_edge:x:local"]
l0_wing = inputs["data:geometry:wing:MAC:length"]
l1_wing = inputs["data:geometry:wing:root:virtual_chord"]
fus_length = inputs["data:geometry:fuselage:length"]
width_max = inputs["data:geometry:fuselage:maximum_width"]
x0_25 = x_wing - 0.25 * l0_wing - x0_wing + 0.25 * l1_wing
ratio_x025 = x0_25 / fus_length
k_fus = self.k_fus(ratio_x025)
cm_alpha_fus = -k_fus * width_max**2 * fus_length / (l0_wing * wing_area) * 180.0 / np.pi
outputs["data:aerodynamics:fuselage:cm_alpha"] = cm_alpha_fus