drag_BWB.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_BWB.ParasiteDragCoefficient_BWB(**kwargs)

Bases: Group

Zero-lift drag coefficient buildup for BWB 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.

NOTE: This component does not include drag from the wing, because it assumes

it is computed by OpenAeroStruct. Add it in!

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|wing|S_ref (float) – Wing planform area (scalar, sq m)

  • 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

  • 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.

  • 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). Set this to zero to neglect drag from flaps, by default 0.

  • drag_fudge_factor (float) – Multiplier on the resulting zero-lift drag coefficient estimate, by default 1.0

  • nacelle_laminar_frac (float) – Fraction of the total engine nacelle length that has a laminary boundary layer, by default 0.0