"""
Estimation of maximum center of gravity ratio.
"""
# 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
from openmdao.core.explicitcomponent import ExplicitComponent
[docs]class ComputeMaxMinCGRatio(ExplicitComponent):
# TODO: Document equations. Cite sources
"""Extrema center of gravity ratio estimation"""
[docs] def setup(self):
self.add_input("data:weight:aircraft:CG:flight_condition:max:MAC_position", val=np.nan)
self.add_input("data:weight:aircraft:CG:flight_condition:min:MAC_position", val=np.nan)
self.add_input("data:weight:aircraft:CG:ground_condition:max:MAC_position", val=np.nan)
self.add_input("data:weight:aircraft:CG:ground_condition:min:MAC_position", val=np.nan)
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("settings:weight:aircraft:CG:range", val=np.nan)
self.add_input(
"settings:weight:aircraft:CG:aft:MAC_position:margin",
val=0.05,
desc="Added margin for getting most aft CG position, "
"as ratio of mean aerodynamic chord",
)
self.add_input(
"settings:weight:aircraft:CG:fwd:MAC_position:margin",
val=0.03,
desc="Added margin for getting most fwd CG position, "
"as ratio of mean aerodynamic chord",
)
self.add_output("data:weight:aircraft:CG:aft:MAC_position")
self.add_output("data:weight:aircraft:CG:fwd:MAC_position")
self.add_output("data:weight:aircraft:CG:aft:x", units="m")
self.add_output("data:weight:aircraft:CG:fwd:x", units="m")
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
ground_conditions_aft = inputs["data:weight:aircraft:CG:ground_condition:max:MAC_position"]
ground_conditions_fwd = inputs["data:weight:aircraft:CG:ground_condition:min:MAC_position"]
flight_conditions_aft = inputs["data:weight:aircraft:CG:flight_condition:max:MAC_position"]
flight_conditions_fwd = inputs["data:weight:aircraft:CG:flight_condition:min:MAC_position"]
cg_range = inputs["settings:weight:aircraft:CG:range"]
margin_aft = inputs["settings:weight:aircraft:CG:aft:MAC_position:margin"]
margin_fwd = inputs["settings:weight:aircraft:CG:fwd:MAC_position:margin"]
l0_wing = inputs["data:geometry:wing:MAC:length"]
mac_position = inputs["data:geometry:wing:MAC:at25percent:x"]
cg_max_aft_mac = max(ground_conditions_aft, flight_conditions_aft) + margin_aft
cg_min_fwd_mac = (
min(ground_conditions_fwd, flight_conditions_fwd, cg_max_aft_mac - cg_range)
- margin_fwd
)
outputs["data:weight:aircraft:CG:aft:MAC_position"] = cg_max_aft_mac
outputs["data:weight:aircraft:CG:fwd:MAC_position"] = cg_min_fwd_mac
outputs["data:weight:aircraft:CG:aft:x"] = (
mac_position - 0.25 * l0_wing + cg_max_aft_mac * l0_wing
)
# Comment this line if ComputeGlobalCG is used
outputs["data:weight:aircraft:CG:fwd:x"] = (
mac_position - 0.25 * l0_wing + cg_min_fwd_mac * l0_wing
)