drag_jet_transport.py

@File : drag_jet_transport.py @Date : 2023/03/23 @Author : Eytan Adler @Description : Zero lift drag coefficient buildup for tube-and-wing jet transport aircraft

class openconcept.aerodynamics.drag_jet_transport.ParasiteDragCoefficient_JetTransport(**kwargs)

Bases: Group

Zero-lift drag coefficient buildup for jet transport aircraft based on a combination of methods from Roskam, Raymer, and the approach presented by OpenVSP (https://openvsp.org/wiki/doku.php?id=parasitedrag). See the individual component docstrings for a more detailed explanation.

Inputs:

fltcond|Utrue (float) – True airspeed (vector, m/s)
fltcond|rho (float) – Air density (vector, kg/m^3)
fltcond|T (float) – Air temperature (vector, K)
ac|geom|fuselage|length (float) – Fuselage length (scalar, m)
ac|geom|fuselage|height (float) – Fuselage height (scalar, m)
ac|geom|fuselage|S_wet (float) – Fuselage wetted area (scalar, sq m)
ac|geom|hstab|S_ref (float) – Horizontal stabilizer planform area (scalar, sq m)
ac|geom|hstab|AR (float) – Horizontal stabilizer aspect ratio (scalar, dimensionless)
ac|geom|hstab|taper (float) – Horizontal stabilizer taper ratio (scalar, dimensionless)
ac|geom|hstab|toverc (float) – Horizontal stabilizer thickness-to-chord ratio (scalar, dimensionless)
ac|geom|vstab|S_ref (float) – Vertical stabilizer planform area (scalar, sq m)
ac|geom|vstab|AR (float) – Vertical stabilizer aspect ratio (scalar, dimensionless)
ac|geom|vstab|taper (float) – Vertical stabilizer taper ratio (scalar, dimensionless)
ac|geom|vstab|toverc (float) – Vertical stabilizer thickness-to-chord ratio (scalar, dimensionless)
ac|geom|wing|S_ref (float) – Wing planform area (scalar, sq m)
ac|geom|wing|AR (float) – If include wing (otherwise not an input), wing aspect ratio (scalar, dimensionless)
ac|geom|wing|taper (float) – If include wing (otherwise not an input), wing taper ratio (scalar, dimensionless)
ac|geom|wing|toverc (float) – If include wing (otherwise not an input), wing thickness-to-chord ratio (scalar, dimensionless)
ac|geom|wing|c4sweep (float) – If configuration is “takeoff” (otherwise not an input), wing quarter chord sweep (scalar, rad)
ac|geom|nacelle|length (float) – Nacelle length (scalar, m)
ac|geom|nacelle|S_wet (float) – Nacelle wetted area (scalar, sq m)
ac|propulsion|num_engines (float) – Number of engines, multiplier on nacelle drag (scalar, dimensionless)
ac|aero|takeoff_flap_deg (float) – If configuration is “takeoff” (otherwise not an input), flap setting on takeoff (scalar, deg)

Outputs:

CD0 (float) – Zero-lift drag coefficient (vector, dimensionless)

Options:

num_nodes (int) – Number of analysis points per phase, by default 1
include_wing (bool) – Include an estimate of the drag of the wing in the output drag estimate, by default True.
configuration (str) – Aircraft configuration, either “takeoff” or “clean”. Takeoff includes drag from landing gear and extended flaps. Clean assumes gear and flaps are retracted.
FF_nacelle (float) – Nacelle form factor. By default 1.25 * 1.2, which is taken from the Jenkinson wing nacelle specified in the OpenVSP documentation (https://openvsp.org/wiki/doku.php?id=parasitedrag) multiplied by a rough estimate of the interference factor of 1.2, appx taken from Raymer. It was originally published in Civil Jet Aircraft by Jenkinson, Simpkin, and Rhodes (1999). Include any desired interference factor in the value provided to this option.
Q_fuselage (float) – Interference factor for fuselage to multiply the form factor estimate. By default 1.0 from Raymer.
Q_tail (float) – Interference factor for horizontal and vertical stabilizers to multiply the form factor estimate. By default 1.05 from Raymer for conventional tail configuration.
Q_wing (float) – Interference factor for wing to multiply the form factor estimate. By default 1.0.
flap_chord_frac (float) – Flap chord divided by wing chord, by default 0.2
Q_flap (float) – Interference drag of flap. By default 1.25, from Roskam Equation 4.75 for Fowler flaps.
wing_area_flapped_frac (float) – Flapped wing area divided by total wing area. Flapped wing area integrates the chord over any portions of the span that contain flaps (not just the area of the flap itself). By default 0.9.
drag_fudge_factor (float) – Multiplier on the resulting zero-lift drag coefficient estimate, by default 1.0
fuselage_laminar_frac (float) – Fraction of the total fuselage length that has a laminary boundary layer, by default 0.0
hstab_laminar_frac (float) – Fraction of the total horizontal stabilizer that has a laminary boundary layer, by default 0.15
vstab_laminar_frac (float) – Fraction of the total vertical stabilizer that has a laminary boundary layer, by default 0.15
wing_laminar_frac (float) – Fraction of the total wing that has a laminary boundary layer, by default 0.15
nacelle_laminar_frac (float) – Fraction of the total engine nacelle length that has a laminary boundary layer, by default 0.0

class openconcept.aerodynamics.drag_jet_transport.FuselageFormFactor_JetTransport(**kwargs)

Bases: ExplicitComponent

Form factor of fuselage based on slender body form factor equation from Torenbeek 1982 (Synthesis of Subsonic Aircraft Design), taken from OpenVSP documentation: https://openvsp.org/wiki/doku.php?id=parasitedrag (accessed March 23, 2023)

Inputs:

ac|geom|fuselage|length (float) – Fuselage structural length (scalar, m)
ac|geom|fuselage|height (float) – Fuselage height (scalar, m)

Outputs:

FF_fuselage (float) – Fuselage form factor (scalar, dimensionless)

Options:

Q_fuselage (float) – Interference factor for fuselage to multiply the form factor estimate. By default 1.0 from Raymer.

class openconcept.aerodynamics.drag_jet_transport.WingFormFactor_JetTransport(**kwargs)

Bases: ExplicitComponent

Form factor of wing times the optional interference factor based on wing form factor equation from Torenbeek 1982 (Synthesis of Subsonic Aircraft Design), but can be applied to other lifting surfaces. Taken from OpenVSP documentation: https://openvsp.org/wiki/doku.php?id=parasitedrag (accessed March 23, 2023)

Inputs:: toverc (float) – Thickness-to-chord ratio of the wing surface
Outputs:: FF_wing (float) – Wing form factor (scalar, dimensionless)
Options:: Q (float) – Interference factor for fuselage to multiply the form factor estimate, by default 1.0

class openconcept.aerodynamics.drag_jet_transport.FlapDrag_JetTransport(**kwargs)

Bases: ExplicitComponent

Estimates the additional drag from extending the flaps using Roskam 1989 Part VI Chapter 4 Equation 4.71 and 4.75. This assumes Fowler flaps.

Inputs:

flap_extension (float) – Flap extension amount (scalar, deg)
ac|geom|wing|c4sweep (float) – Wing sweep at 25% mean aerodynamic chord (scalar, radians)

Outputs:

CD_flap (float) – Increment to drag coefficient from flap profile drag (scalar, dimensionless)

Options:

flap_chord_frac (float) – Flap chord divided by wing chord, by default 0.2
Q_flap (float) – Interference drag of flap. By default 1.25, from Roskam Equation 4.75 for Fowler flaps.
wing_area_flapped_frac (float) – Flapped wing area divided by total wing area. Flapped wing area integrates the chord over any portions of the span that contain flaps (not just the area of the flap itself). By default 0.9.

class openconcept.aerodynamics.drag_jet_transport.SkinFrictionCoefficient_JetTransport(**kwargs)

Bases: ExplicitComponent

Compute the average coefficient of friction using the methodology described here: https://openvsp.org/wiki/doku.php?id=parasitedrag. It uses the Blasius and explicit fit of Spalding correlations.

Inputs:

L (float) – Characteristic length to use in the Reynolds number computation (scalar, m)
fltcond|Utrue (float) – True airspeed (vector, m/s)
fltcond|rho (float) – Air density (vector, kg/m^3)
fltcond|T (float) – Air temperature (vector, K)

Outputs:

Cf (float) – Skin friction coefficient (vector, dimensionless)

Options:

num_nodes (int) – Number of analysis points per phase, by default 1
laminar_frac (float) – Fraction of total length that has a laminar boundary layer, by default 0.0