aerosandbox.library.aerodynamics.components#

Module Contents#

Functions#

CDA_control_linkage(Re_l, linkage_length[, ...])

Computes the drag area (CDA) of a typical control usage as used on a well-manufactured RC airplane.

CDA_control_surface_gaps(local_chord, control_surface_span)

Computes the drag area (CDA) of the gaps associated with a typical wing control surface.

CDA_protruding_bolt_or_rivet(diameter[, kind])

Computes the drag area (CDA) of a protruding bolt or rivet.

CDA_perpendicular_sheet_metal_joint(joint_width, ...)

Computes the drag area (CDA) of a sheet metal joint that is perpendicular to the flow.
aerosandbox.library.aerodynamics.components.CDA_control_linkage(Re_l, linkage_length, is_covered=False, is_top=False)[source]#

Computes the drag area (CDA) of a typical control usage as used on a well-manufactured RC airplane.

The drag area (CDA) is defined as: CDA == D / q, where:

  • D is the drag force (dimensionalized, e.g., in Newtons)

  • q is the freestream dynamic pressure (dimensionalized, e.g., in Pascals)

See study with original data at AeroSandbox/studies/LinkageDrag.

Data from:

Parameters:

  • Re_l (Union[float, aerosandbox.numpy.ndarray]) – Reynolds number, with reference length as the length of the linkage.

  • linkage_length (Union[float, aerosandbox.numpy.ndarray]) – The length of the linkage. [m]

  • is_covered (Union[bool, aerosandbox.numpy.ndarray]) – A boolean of whether an aerodynamic fairing is placed around the linkage.

  • is_top (Union[bool, aerosandbox.numpy.ndarray]) – A boolean of whether the linkage is on the top surface of the wing (True) or the bottom surface ( False). Differences in local boundary layer and inviscid effects cause local velocity changes.

Return type:

Union[float, aerosandbox.numpy.ndarray]

Returns: The drag area [m^2] of the control linkage.

aerosandbox.library.aerodynamics.components.CDA_control_surface_gaps(local_chord, control_surface_span, local_thickness_over_chord=0.12, control_surface_hinge_x=0.75, n_side_gaps=2, side_gap_width=None, hinge_gap_width=None)[source]#

Computes the drag area (CDA) of the gaps associated with a typical wing control surface. (E.g., aileron, flap, elevator, rudder).

The drag area (CDA) is defined as: CDA == D / q, where:

  • D is the drag force (dimensionalized, e.g., in Newtons)

  • q is the freestream dynamic pressure (dimensionalized, e.g., in Pascals)

This drag area consists of two sources:

  1. Chordwise gaps at the side edges of the control surface (“side gaps”)

  2. Spanwise gaps at the hinge line of the control surface (“hinge gap”)

Parameters:

  • local_chord (float) – The local chord of the wing at the midpoint of the control surface. [meters]

  • control_surface_span (float) – The span of the control surface. [meters]

  • local_thickness_over_chord (float) – The local thickness-to-chord ratio of the wing at the midpoint of the control surface. [nondimensional] For example, this is 0.12 for a NACA0012 airfoil.

  • control_surface_hinge_x (float) – The x-location of the hinge line of the control surface, as a fraction of the local chord. [nondimensional] Defaults to x_hinge / c = 0.75, which is typical for an aileron.

  • n_side_gaps (int) –

    The number of “side gaps” to count on this control surface when computing drag. Defaults to 2 ( i.e., one inboard gap, one outboard gap), which is the simplest case of a wing with a single partial-span aileron. However, there may be cases where it is best to reduce this to 1 or 0. For example:

    • A wing with a single full-span aileron would have 1 side gap (at the wing root, but not at the tip).

    • A wing with a flap and aileron that share a chordwise gap would be best modeled by setting

      n_side_gaps = 1 ( so that no double-counting occurs).

  • side_gap_width (float) – The width of the chordwise gaps at the side edges of the control surface [meters]. If this is left as the default (None), then a typical value will be computed based on the local chord and control surface span.

  • hinge_gap_width (float) – The width of the spanwise gap at the hinge line of the control surface [meters]. If this is left as the default (None), then a typical value will be computed based on the local chord.

Return type:

float

Returns: The drag area [m^2] of the gaps associated with the control surface. This should be added to the “clean”

wing drag to get a more realistic drag estimate.

aerosandbox.library.aerodynamics.components.CDA_protruding_bolt_or_rivet(diameter, kind='flush_rivet')[source]#

Computes the drag area (CDA) of a protruding bolt or rivet.

The drag area (CDA) is defined as: CDA == D / q, where:

  • D is the drag force (dimensionalized, e.g., in Newtons)

  • q is the freestream dynamic pressure (dimensionalized, e.g., in Pascals)

Parameters:

  • diameter (float) – The diameter of the bolt or rivet. [meters]

  • kind (str) –

    The type of bolt or rivet. Valid options are:

    • ”flush_rivet”

    • ”round_rivet”

    • ”flat_head_bolt”

    • ”round_head_bolt”

    • ”cylindrical_bolt”

    • ”hex_bolt”

Returns: The drag area [m^2] of the bolt or rivet.

aerosandbox.library.aerodynamics.components.CDA_perpendicular_sheet_metal_joint(joint_width, sheet_metal_thickness, kind='butt_joint_with_inside_joiner')[source]#
Computes the drag area (CDA) of a sheet metal joint that is perpendicular to the flow.

(E.g., spanwise on the wing, or circumferential on the fuselage).

The drag area (CDA) is defined as: CDA == D / q, where:

  • D is the drag force (dimensionalized, e.g., in Newtons)

  • q is the freestream dynamic pressure (dimensionalized, e.g., in Pascals)

Parameters:

  • joint_width (float) – The width of the joint (perpendicular to the airflow, e.g., spanwise on a wing). [meters]

  • sheet_metal_thickness (float) – The thickness of the sheet metal. [meters]

  • kind (str) –

    The type of joint. Valid options are:

    • ”butt_joint_with_inside_joiner”

    • ”butt_joint_with_inside_weld”

    • ”butt_joint_with_outside_joiner”

    • ”butt_joint_with_outside_weld”

    • ”lap_joint_forward_facing_step”

    • ”lap_joint_backward_facing_step”

    • ”lap_joint_forward_facing_step_with_bevel”

    • ”lap_joint_backward_facing_step_with_bevel”

    • ”lap_joint_forward_facing_step_with_rounded_bevel”

    • ”lap_joint_backward_facing_step_with_rounded_bevel”

    • ”flush_lap_joint_forward_facing_step”

    • ”flush_lap_joint_backward_facing_step”

Returns: The drag area [m^2] of the sheet metal joint.