"""
Python module for aircraft length calculation, part of the fuselage dimension.
"""
# This file is part of FAST-OAD_CS23 : A framework for rapid Overall Aircraft Design
# Copyright (C) 2025 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
[docs]class ComputeAircraftLength(om.ExplicitComponent):
"""
Computes aircraft length.
"""
# pylint: disable=missing-function-docstring
# Overriding OpenMDAO setup
[docs] def setup(self):
self.add_input("data:geometry:wing:MAC:at25percent:x", val=np.nan, units="m")
self.add_input(
"data:geometry:horizontal_tail:MAC:at25percent:x:from_wingMAC25", val=np.nan, units="m"
)
self.add_input(
"data:geometry:vertical_tail:MAC:at25percent:x:from_wingMAC25", val=np.nan, units="m"
)
self.add_input("data:geometry:horizontal_tail:MAC:length", val=np.nan, units="m")
self.add_input("data:geometry:vertical_tail:MAC:length", val=np.nan, units="m")
self.add_input("data:geometry:horizontal_tail:sweep_25", val=np.nan, units="rad")
self.add_input("data:geometry:horizontal_tail:span", val=np.nan, units="m")
self.add_input("data:geometry:vertical_tail:sweep_25", val=np.nan, units="rad")
self.add_input("data:geometry:vertical_tail:span", val=np.nan, units="m")
self.add_output("data:geometry:aircraft:length", units="m")
self.declare_partials(of="*", wrt="*", method="exact")
self.declare_partials("*", "data:geometry:wing:MAC:at25percent:x", val=1.0)
# pylint: disable=missing-function-docstring, unused-argument
# Overriding OpenMDAO compute, not all arguments are used
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
fa_length = inputs["data:geometry:wing:MAC:at25percent:x"]
ht_lp = inputs["data:geometry:horizontal_tail:MAC:at25percent:x:from_wingMAC25"]
vt_lp = inputs["data:geometry:vertical_tail:MAC:at25percent:x:from_wingMAC25"]
ht_length = inputs["data:geometry:horizontal_tail:MAC:length"]
vt_length = inputs["data:geometry:vertical_tail:MAC:length"]
sweep_25_vt = inputs["data:geometry:vertical_tail:sweep_25"]
b_v = inputs["data:geometry:vertical_tail:span"]
sweep_25_ht = inputs["data:geometry:horizontal_tail:sweep_25"]
b_h = inputs["data:geometry:horizontal_tail:span"]
aircraft_length = fa_length + max(
ht_lp + 0.75 * ht_length + b_h / 2.0 * np.tan(sweep_25_ht),
vt_lp + 0.75 * vt_length + b_v * np.tan(sweep_25_vt),
)
outputs["data:geometry:aircraft:length"] = aircraft_length
# pylint: disable=missing-function-docstring, unused-argument
# Overriding OpenMDAO compute_partials, not all arguments are used
[docs] def compute_partials(self, inputs, partials, discrete_inputs=None):
ht_lp = inputs["data:geometry:horizontal_tail:MAC:at25percent:x:from_wingMAC25"]
vt_lp = inputs["data:geometry:vertical_tail:MAC:at25percent:x:from_wingMAC25"]
ht_length = inputs["data:geometry:horizontal_tail:MAC:length"]
vt_length = inputs["data:geometry:vertical_tail:MAC:length"]
sweep_25_vt = inputs["data:geometry:vertical_tail:sweep_25"]
b_v = inputs["data:geometry:vertical_tail:span"]
sweep_25_ht = inputs["data:geometry:horizontal_tail:sweep_25"]
b_h = inputs["data:geometry:horizontal_tail:span"]
if (ht_lp + 0.75 * ht_length + b_h / 2.0 * np.tan(sweep_25_ht)) > (
vt_lp + 0.75 * vt_length + b_v * np.tan(sweep_25_vt)
):
partials[
"data:geometry:aircraft:length",
"data:geometry:horizontal_tail:MAC:at25percent:x:from_wingMAC25",
] = 1.0
partials[
"data:geometry:aircraft:length", "data:geometry:horizontal_tail:MAC:length"
] = 0.75
partials["data:geometry:aircraft:length", "data:geometry:horizontal_tail:sweep_25"] = (
b_h * (np.tan(sweep_25_ht) ** 2.0 + 1.0) / 2.0
)
partials["data:geometry:aircraft:length", "data:geometry:horizontal_tail:span"] = (
np.tan(sweep_25_ht) / 2.0
)
partials[
"data:geometry:aircraft:length",
"data:geometry:vertical_tail:MAC:at25percent:x:from_wingMAC25",
] = 0.0
partials["data:geometry:aircraft:length", "data:geometry:vertical_tail:MAC:length"] = (
0.0
)
partials["data:geometry:aircraft:length", "data:geometry:vertical_tail:sweep_25"] = 0.0
partials["data:geometry:aircraft:length", "data:geometry:vertical_tail:span"] = 0.0
else:
partials[
"data:geometry:aircraft:length",
"data:geometry:horizontal_tail:MAC:at25percent:x:from_wingMAC25",
] = 0.0
partials[
"data:geometry:aircraft:length", "data:geometry:horizontal_tail:MAC:length"
] = 0.0
partials["data:geometry:aircraft:length", "data:geometry:horizontal_tail:sweep_25"] = (
0.0
)
partials["data:geometry:aircraft:length", "data:geometry:horizontal_tail:span"] = 0.0
partials[
"data:geometry:aircraft:length",
"data:geometry:vertical_tail:MAC:at25percent:x:from_wingMAC25",
] = 1.0
partials["data:geometry:aircraft:length", "data:geometry:vertical_tail:MAC:length"] = (
0.75
)
partials["data:geometry:aircraft:length", "data:geometry:vertical_tail:sweep_25"] = (
b_v * (np.tan(sweep_25_vt) ** 2.0 + 1.0)
)
partials["data:geometry:aircraft:length", "data:geometry:vertical_tail:span"] = np.tan(
sweep_25_vt
)