"""
Estimation of center of gravity for load case 4
"""
# This file is part of FAST-OAD : A framework for rapid Overall Aircraft Design
# Copyright (C) 2021 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
from openmdao.core.explicitcomponent import ExplicitComponent
[docs]class ComputeCGLoadCase4(ExplicitComponent):
# TODO: Document equations. Cite sources
""" Center of gravity estimation for load case 4 """
[docs] def setup(self):
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:weight:payload:PAX:CG:x", val=np.nan, units="m")
self.add_input("data:weight:payload:rear_fret:CG:x", val=np.nan, units="m")
self.add_input("data:weight:payload:front_fret:CG:x", val=np.nan, units="m")
self.add_input("data:TLAR:NPAX", val=np.nan)
self.add_input("data:weight:aircraft_empty:CG:x", val=np.nan, units="m")
self.add_input("data:weight:aircraft_empty:mass", val=np.nan, units="kg")
self.add_output("data:weight:aircraft:load_case_4:CG:MAC_position")
[docs] def setup_partials(self):
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
l0_wing = inputs["data:geometry:wing:MAC:length"]
fa_length = inputs["data:geometry:wing:MAC:at25percent:x"]
cg_pax = inputs["data:weight:payload:PAX:CG:x"]
cg_rear_fret = inputs["data:weight:payload:rear_fret:CG:x"]
cg_front_fret = inputs["data:weight:payload:front_fret:CG:x"]
npax = inputs["data:TLAR:NPAX"]
x_cg_plane_aft = inputs["data:weight:aircraft_empty:CG:x"]
x_cg_plane_down = inputs["data:weight:aircraft_empty:mass"]
x_cg_plane_up = x_cg_plane_aft * x_cg_plane_down
weight_pax = npax * 90.0
weight_rear_fret = npax * 30.0
weight_front_fret = npax * 10.0
weight_pl = weight_pax + weight_rear_fret + weight_front_fret
x_cg_pl_4 = (
weight_pax * cg_pax
+ weight_rear_fret * cg_rear_fret
+ weight_front_fret * cg_front_fret
) / weight_pl
x_cg_plane_pl_4 = (x_cg_plane_up + weight_pl * x_cg_pl_4) / (
x_cg_plane_down + weight_pl
) # forward
cg_ratio_pl_4 = (x_cg_plane_pl_4 - fa_length + 0.25 * l0_wing) / l0_wing
outputs["data:weight:aircraft:load_case_4:CG:MAC_position"] = cg_ratio_pl_4