Wing Geometry

This section defines the parametric model for wings. The Wing model is versatile enough to represent main wings, horizontal stabilizers, and vertical stabilizers.

Structure: Station-based Profiles

In this standard, a wing is defined by a series of Stations (Profiles) at specific spanwise positions. Each station defines the airfoil shape, chord, and orientation at that location.

Station (Profile): Defines the 2D cross-section at a specific point along the span. It includes position, orientation, geometric properties (chord, airfoil), and rotations.

Stations are connected by lofting to create the 3D wing surface.

Coordinate Frame and Placement

Each wing's stations are defined in a wing-local coordinate system where:

Origin: Wing attachment point (leading edge of root)
X+: Aft (toward trailing edge direction)
Y+: Outboard (toward wing tip)
Z+: Up (perpendicular to wing reference plane)

The entire wing is then positioned in the airframe using Wing Attachment parameters (see Wing Attachment section).

Root Offset: Specified in Wing Attachment (position relative to fuselage nose)
Symmetry: Wings are mirrored using the mirror parameter in Wing Attachment.

Parameters

Identification and Mass

Parameter	Type	Description
tag	`str`	Unique identifier for the wing (e.g., "main_wing", "v_tail_left").
mass	`g`	Total wing mass for a single wing (optional). Note: if mirror is true in wing attachment, total mass will be 2 × mass.

Geometry

A wing geometry is defined by a list of stations (profiles). Each station fully specifies its position and orientation.

Station Properties

Parameter	Unit	Description
position	`object`	Station position (required).
position.x	`mm`	Longitudinal position in wing-local frame (typically 0 for leading edge with no sweep angle, positive = aft).
position.y	`mm`	Spanwise position from wing root (0 = root, increases toward tip).
position.z	`mm`	Vertical position from wing reference plane (0 = reference, positive = up).
chord	`mm`	Chord length at this station.
airfoil	`str\\|obj`	Airfoil definition. Supports simple string format (e.g., `"naca2412"`) or detailed object format. See Airfoil Definition section for details.
rotation	`object`	Station rotation (optional).
rotation.x	`deg`	Rotation around X-axis (roll, optional, default: 0).
rotation.y	`deg`	Rotation around Y-axis (pitch/incidence/twist angle at this station, optional, default: 0).
rotation.z	`deg`	Rotation around Z-axis (yaw, optional, default: 0).

Airfoil Definition

Airfoils can be defined in two formats:

1. Simple Format (String): For backward compatibility and simplicity, NACA airfoils can be specified directly as strings:

airfoil: "naca2412"

2. Detailed Format (Object): For greater flexibility and different source types, use the object format:

Parameter	Type	Description
type	`enum`	Airfoil type: `naca`, `file`, `coordinates`.
code	`str`	NACA code (required for `type: naca`). E.g., `"2412"`, `"0012"`.
path	`str`	DAT file path (required for `type: file`). Relative path from project root.
points	`array`	Coordinate array (required for `type: coordinates`). Normalized coordinates (0-1 range) in `[[x, y], ...]` format.

Examples:

# NACA airfoil
airfoil:
  type: "naca"
  code: "2412"

# DAT file
airfoil:
  type: "file"
  path: "profiles/custom_airfoil.dat"

# Coordinate table
airfoil:
  type: "coordinates"
  points: [[1.0, 0.0], [0.95, 0.012], [0.90, 0.018], ...]

Surface Generation Parameters

These parameters control how adjacent profiles are blended to create the wing surface.

Parameter	Type	Default	Description
ruled	`bool`	`false`	`false`: Smooth approximated surface. `true`: Ruled surface (straight lines between profiles).
max_degree	`int`	`3`	Maximum polynomial degree for B-spline approximation. Valid range: `1-8`. Higher values allow smoother curves.
continuity	`enum`	`G2`	Target surface smoothness: `G0` (positional continuity), `G1` (tangent continuity), `G2` (curvature continuity).

Control Surfaces

Control surfaces are movable surfaces mapped to specific spanwise regions of the wing geometry. Ailerons, Flaps, Elevators, and similar surfaces are defined this way.

Control Surface Parameters

Parameter	Unit	Description
tag	`str`	Unique identifier for the control surface (e.g., "left_aileron", "flap").
type	`enum`	Control surface type: `aileron`, `flap`, `elevator`, `rudder`.
span_start	`mm`	Spanwise position where the control surface starts (corresponds to position_y coordinate).
span_end	`mm`	Spanwise position where the control surface ends (corresponds to position_y coordinate).
chord	`mm`	Chord length of the control surface. Measured from trailing edge at each station.

Note: The hinge line is implicitly defined at the control surface start (at chord mm distance from the trailing edge).

Example Control Surface Definition

control_surfaces:
  - tag: "left_aileron"
    type: "aileron"
    span_start: 500    # Starts at 500mm from root
    span_end: 800      # Ends at 800mm from root
    chord: 60          # 60mm chord length

  - tag: "flap"
    type: "flap"
    span_start: 100
    span_end: 450
    chord: 75

Example Configuration

tag: "main_wing"
mass: 180  # optional
type: "wing"
geometry:
  blending:
    ruled: false
    max_degree: 3
    continuity: "G2"

  profiles:
    - position:            # Root profile at leading edge
        x: 0
        y: 0
        z: 0
      chord: 240
      rotation:
        y: 2.0
      airfoil: "naca2412"  # Simple format

    - position:            # Mid-span profile
        x: 0
        y: 400
        z: 0
      chord: 240
      rotation:
        y: 2.0
      airfoil:              # Detailed format
        type: "naca"
        code: "2412"

    - position:            # Tip profile (swept and dihedral)
        x: 35
        y: 800
        z: 35
      chord: 180
      rotation:
        y: -1.0  # Washout
      airfoil:
        type: "naca"
        code: "0012"

  control_surfaces:
    - tag: "left_aileron"
      type: "aileron"
      span_start: 500
      span_end: 800
      chord: 60

    - tag: "flap"
      type: "flap"
      span_start: 100
      span_end: 450
      chord: 75