"""
Python module for the computation of maneuver and gust sizing load case envelope.
"""
# This file is part of FAST-OAD : 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 fastoad.api as oad
import numpy as np
import openmdao.api as om
from scipy.constants import g
from ..constants import SERVICE_SIZING_LOADS_ENVELOPE
[docs]
@oad.RegisterSubmodel(SERVICE_SIZING_LOADS_ENVELOPE, "fastoad.submodel.loads.envelope.legacy")
class SizingLoadsEnvelope(om.ExplicitComponent):
"""
Computes CS25 sizing loads evaluated at two different load cases:
Load case 1: with wings with almost no fuel
Load case 2: at maximum take-off weight
Based on formulas in :cite:`supaero:2014`, ยง6.3.
"""
[docs]
def initialize(self):
self.options.declare(
"fuel_load_alleviation",
types=bool,
default=True,
desc="If False this simulates a dry wing,"
"i.e. the sizing load 2 does not take into account the fuel weight.",
)
[docs]
def setup(self):
self.add_input("data:weight:aircraft:MZFW", val=np.nan, units="kg")
self.add_input("data:weight:aircraft:MFW", val=np.nan, units="kg")
self.add_input("data:weight:aircraft:MTOW", val=np.nan, units="kg")
self.add_input("data:mission:sizing:cs25:gust:load_factor_1", units="unitless")
self.add_input("data:mission:sizing:cs25:gust:load_factor_2", units="unitless")
self.add_input("data:mission:sizing:cs25:maneuver:load_factor_1", units="unitless")
self.add_input("data:mission:sizing:cs25:maneuver:load_factor_2", units="unitless")
self.add_output("data:mission:sizing:cs25:envelope:max_load_factor_1", units="unitless")
self.add_output("data:mission:sizing:cs25:envelope:max_load_factor_2", units="unitless")
self.add_output("data:mission:sizing:cs25:envelope:max_sizing_load_1", units="N")
self.add_output("data:mission:sizing:cs25:envelope:max_sizing_load_2", units="N")
[docs]
def setup_partials(self):
# Load factor outputs
self.declare_partials(
"data:mission:sizing:cs25:envelope:max_load_factor_1",
[
"data:mission:sizing:cs25:gust:load_factor_1",
"data:mission:sizing:cs25:maneuver:load_factor_1",
],
method="fd",
)
self.declare_partials(
"data:mission:sizing:cs25:envelope:max_load_factor_2",
[
"data:mission:sizing:cs25:gust:load_factor_2",
"data:mission:sizing:cs25:maneuver:load_factor_2",
],
method="fd",
)
# Sizing load outputs
self.declare_partials(
"data:mission:sizing:cs25:envelope:max_sizing_load_1",
[
"data:mission:sizing:cs25:gust:load_factor_1",
"data:mission:sizing:cs25:maneuver:load_factor_1",
"data:weight:aircraft:MZFW",
],
method="fd",
)
self.declare_partials(
"data:mission:sizing:cs25:envelope:max_sizing_load_2",
[
"data:mission:sizing:cs25:gust:load_factor_2",
"data:mission:sizing:cs25:maneuver:load_factor_2",
"data:weight:aircraft:MFW",
"data:weight:aircraft:MTOW",
],
method="fd",
)
[docs]
def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
mzfw = inputs["data:weight:aircraft:MZFW"]
mfw = inputs["data:weight:aircraft:MFW"]
mtow = inputs["data:weight:aircraft:MTOW"]
n1_maneuver = inputs["data:mission:sizing:cs25:maneuver:load_factor_1"]
n2_maneuver = inputs["data:mission:sizing:cs25:maneuver:load_factor_2"]
n1_gust = inputs["data:mission:sizing:cs25:gust:load_factor_1"]
n2_gust = inputs["data:mission:sizing:cs25:gust:load_factor_2"]
# load case #1
m1 = 1.05 * mzfw
# load case #2
if not self.options["fuel_load_alleviation"]:
m2 = mtow
else:
mcv = min(0.8 * mfw, mtow - mzfw) # fuel mass in the overhanging part of wing
m2 = mtow - 0.55 * mcv
n1 = max(n1_gust, n1_maneuver)
n2 = max(n2_gust, n2_maneuver)
n1m1 = n1 * m1 * g
n2m2 = n2 * m2 * g
outputs["data:mission:sizing:cs25:envelope:max_load_factor_1"] = n1
outputs["data:mission:sizing:cs25:envelope:max_load_factor_2"] = n2
outputs["data:mission:sizing:cs25:envelope:max_sizing_load_1"] = n1m1
outputs["data:mission:sizing:cs25:envelope:max_sizing_load_2"] = n2m2