"""
Python module for the computation of maneuver sizing load cases.
"""
# This file is part of FAST-OAD_CS25
# Copyright (C) 2023 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 openmdao.api import convert_units
from ..constants import SERVICE_MANEUVER_LOADS
[docs]
@oad.RegisterSubmodel(SERVICE_MANEUVER_LOADS, "fastoad.submodel.loads.maneuver.legacy")
class ManeuverLoads(om.ExplicitComponent):
"""
Computes CS25 pull-up maneuver load factors 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 setup(self):
self.add_input("data:load_case:maneuver_load_factor", val=0.0, units="unitless")
self.add_input("data:mission:sizing:cs25:safety_factor", val=1.5, units="unitless")
self.add_input("data:weight:aircraft:MTOW", val=np.nan, units="kg")
self.add_output("data:mission:sizing:cs25:maneuver:load_factor_1", units="unitless")
self.add_output("data:mission:sizing:cs25:maneuver:load_factor_2", units="unitless")
[docs]
def setup_partials(self):
self.declare_partials(
"data:mission:sizing:cs25:maneuver:load_factor_1",
"*",
method="fd",
)
self.declare_partials(
"data:mission:sizing:cs25:maneuver:load_factor_2",
"*",
method="fd",
)
[docs]
def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
n_maneuver = inputs["data:load_case:maneuver_load_factor"]
safety_factor = inputs["data:mission:sizing:cs25:safety_factor"]
mtow = inputs["data:weight:aircraft:MTOW"]
if (
n_maneuver == 0.0
): # n_maneuver not provided by the user, so we evaluate it using CS 25.337
n_maneuver = self.__n_maneuver(mtow)
# load case #1
n1 = safety_factor * n_maneuver
# load case #2
n2 = safety_factor * n_maneuver
outputs["data:mission:sizing:cs25:maneuver:load_factor_1"] = n1
outputs["data:mission:sizing:cs25:maneuver:load_factor_2"] = n2
@staticmethod
def __n_maneuver(w_kg):
"""
See CS 25.337 Limit manoeuvring load factors.
Computes the maneuver load factor based on gross weight (in kg).
- Converts weight to pounds.
- Uses the formula: 2 * (1 + 24000 / (w + 10000))
- Clip the result between 2.5 and 3.8.
"""
w = convert_units(w_kg, "kg", "lb")
raw_n = 2 * (1 + 24000 / (w + 10000))
return np.clip(raw_n, 2.5, 3.8)