Source code for RCAIDE.Library.Methods.Aerodynamics.Common.Drag.induced_drag
# RCAIDE/Library/Methods/Aerodynamics/Common/Drag/induced_drag.py
# (c) Copyright 2023 Aerospace Research Community LLC
#
# Created: Jun 2024, M. Clarke
# ----------------------------------------------------------------------------------------------------------------------
# IMPORT
# ----------------------------------------------------------------------------------------------------------------------
# RCAIDE imporst
from RCAIDE.Framework.Core import Data
# package imports
import numpy as np
# ----------------------------------------------------------------------
# Induced Drag Aircraft
# ----------------------------------------------------------------------
[docs]
def induced_drag(state,settings,geometry):
"""Determines induced drag for the full aircraft
Assumptions:
This function operates in one of three ways:
-An oswald efficiency is provided. All induced drag, inviscid and viscous, is use calculated using that factor
-A span efficiency is provided. The inviscid induced drag is calculated from that. Viscous induced drag is
calculated using the viscous_lift_dependent_drag_factor, K, and the parasite drag.
-The inviscid induced drag from the the lift calculation for each wing, usually a vortex lattice, is used. Viscous induced drag is
calculated using the viscous_lift_dependent_drag_factor, K, and the parasite drag.
The last two options do not explicitly provide for the case where the fuselage produces an induced drag directly.
Source:
adg.stanford.edu (Stanford AA241 A/B Course Notes)
http://aerodesign.stanford.edu/aircraftdesign/aircraftdesign.html
Inputs:
state.conditions.aerodynamics.
lift_coefficient [Unitless]
lift_breakdown.inviscid_wings[wings.*.tag] [Unitless]
drag_breakdown.induced.inviscid [Unitless]
drag_breakdown.induced.inviscid_wings[wings.*.tag] [Unitless]
drag_breakdown.parasite[wings.*.tag].parasite_drag_coefficient [Unitless]
drag_breakdown.parasite[wings.*.tag].reference_area [m^2]
settings.oswald_efficiency_factor [Unitless]
settings.viscous_lift_dependent_drag_factor [Unitless]
settings.span_efficiency [Unitless]
Outputs:
conditions.aerodynamics.coefficients.drag.induced.
total [Unitless]
viscous [Unitless]
oswald_efficiency_factor [Unitless]
viscous_wings_drag [Unitless]
total_induced_drag [Unitless]
Properties Used:
N/A
"""
# unpack inputs
wings = geometry.wings
K = settings.viscous_lift_dependent_drag_factor
e_osw = settings.oswald_efficiency_factor
aero = state.conditions.aerodynamics.coefficients
CL = aero.lift.total
CDi = aero.drag.induced.inviscid
wing_viscous_induced_drags = Data()
# If the oswald efficiency factor is not specified
if e_osw == None:
# Prime totals
area = 1E-12
AR = 1E-12
total_viscous_induced_drag = K*aero.drag.parasite.total*(CL**2)
# Go through each wing, and make calculations
for wing in wings:
AR_wing = wing.aspect_ratio
S_wing = aero.drag.parasite[wing.tag].reference_area
if S_wing > area:
area = S_wing
AR = AR_wing
# compute total induced drag
total_induced_drag = total_viscous_induced_drag + CDi
# Calculate the vehicle level oswald efficiency
e_osw = (CL**2)/(np.pi*AR*total_induced_drag)
# If the user specifies a vehicle level oswald efficiency factor
else:
# Find the largest wing, use that for AR
S = 1E-12
AR = 1E-12
for wing in wings:
if wing.areas.reference>S:
AR = wing.aspect_ratio
S = wing.areas.reference
# Calculate the induced drag
total_induced_drag = CL **2 / (np.pi*AR*e_osw)
total_viscous_induced_drag = total_induced_drag - CDi
aero.drag.induced.total = total_induced_drag
aero.drag.induced.viscous = total_viscous_induced_drag
aero.drag.induced.oswald_efficiency_factor = e_osw
aero.drag.induced.viscous_wings_drag = wing_viscous_induced_drags
return
