"""
Estimation of pylons weight
"""
# 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
import openmdao.api as om
[docs]class PylonsWeight(om.ExplicitComponent):
"""
Weight estimation for pylons
Based on formula in :cite:`supaero:2014`, mass contribution A6
"""
[docs] def setup(self):
self.add_input("data:geometry:propulsion:pylon:wetted_area", val=np.nan, units="m**2")
self.add_input("data:geometry:propulsion:layout", val=np.nan)
self.add_input("data:weight:propulsion:engine:mass", val=np.nan, units="kg")
self.add_input("data:geometry:propulsion:engine:count", val=np.nan)
self.add_input("tuning:weight:airframe:pylon:mass:k", val=1.0)
self.add_input("tuning:weight:airframe:pylon:mass:offset", val=0.0, units="kg")
self.add_output("data:weight:airframe:pylon:mass", units="kg")
[docs] def setup_partials(self):
self.declare_partials("*", "*", method="fd")
[docs] def compute(self, inputs, outputs, discrete_inputs=None, discrete_outputs=None):
wet_area_pylon = inputs["data:geometry:propulsion:pylon:wetted_area"]
weight_engine = inputs["data:weight:propulsion:engine:mass"]
n_engines = inputs["data:geometry:propulsion:engine:count"]
k_a6 = inputs["tuning:weight:airframe:pylon:mass:k"]
offset_a6 = inputs["tuning:weight:airframe:pylon:mass:offset"]
propulsion_layout = np.round(inputs["data:geometry:propulsion:layout"])
if propulsion_layout == 1.0:
temp_a6 = (
1.2
* wet_area_pylon ** 0.5
* n_engines
* (23 + 0.588 * (weight_engine / n_engines) ** 0.708)
)
else:
temp_a6 = 0.08 * weight_engine
outputs["data:weight:airframe:pylon:mass"] = k_a6 * temp_a6 + offset_a6