"""
Estimation of horizontal tail lift coefficient
"""
# 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 math
import numpy as np
from openmdao.core.explicitcomponent import ExplicitComponent
# TODO: This belongs more to aerodynamics than geometry
[docs]class ComputeHTClalpha(ExplicitComponent):
# TODO: Document equations. Cite sources
""" Horizontal tail lift coefficient estimation """
[docs] def setup(self):
self.add_input("data:geometry:horizontal_tail:aspect_ratio", val=np.nan)
self.add_input("data:TLAR:cruise_mach", val=np.nan)
self.add_input("data:geometry:horizontal_tail:sweep_25", val=np.nan, units="deg")
self.add_output("data:aerodynamics:horizontal_tail:cruise:CL_alpha")
[docs] def setup_partials(self):
self.declare_partials("data:aerodynamics:horizontal_tail:cruise:CL_alpha", "*", method="fd")
[docs] def compute(self, inputs, outputs):
cruise_mach = inputs["data:TLAR:cruise_mach"]
lambda_ht = inputs["data:geometry:horizontal_tail:aspect_ratio"]
sweep_25_ht = inputs["data:geometry:horizontal_tail:sweep_25"]
beta = math.sqrt(1 - cruise_mach ** 2)
cl_alpha_ht = (
0.8
* 2
* math.pi
* lambda_ht
/ (
2
+ math.sqrt(
4
+ lambda_ht ** 2
* beta ** 2
/ 0.95 ** 2
* (1 + (math.tan(sweep_25_ht / 180.0 * math.pi)) ** 2 / beta ** 2)
)
)
)
outputs["data:aerodynamics:horizontal_tail:cruise:CL_alpha"] = cl_alpha_ht