Concepts

This section explains the main concepts and data structures used in OpenGlider.

Glider hierarchy

A Glider is the top-level 3D representation of a paraglider or kite. It consists of:

  • Cells — each cell is the volume between two ribs (and optional miniribs).

  • Ribs — define the wing profile at a given span position; each rib has an airfoil, twist (angle of attack), and position.

  • LineSet — lines and attachment points (nodes) that connect the canopy to the harness.

Structure:

Glider
├── Cells (list of Cell)
│   ├── rib1, rib2 (Rib)
│   ├── miniribs (optional)
│   ├── panels, diagonals, straps
│   └── ...
└── LineSet
    ├── lines (Line)
    └── attachment points (nodes)

To build a glider you typically create ribs first, then cells from adjacent ribs, then attach a LineSet.

Coordinate system

  • x — longitudinal (positive = forward / nose).

  • y — span (positive = right wing).

  • z — vertical (positive = up).

Airfoil / profile coordinates

Profiles follow the common .dat convention: a list of (x, y) points from trailing edge (upper) via nose to trailing edge (lower). For convenience, profile points can be queried by a normalised x in (-1, 1):

  • x < 0 — upper surface

  • x = 0 — nose

  • x > 0 — lower surface

Ballooning

Ballooning (excess fabric between ribs) is defined per rib in OpenGlider. It affects the 3D shape of the canopy between ribs.

Parametric vs 3D glider

  • ParametricGlider — 2D/parametric representation (shape, arc, profile distribution, spreadsheet-style). Used for design and import from ODS.

  • Glider — 3D geometry built from cells and ribs. Used for mesh export, lines, and visualisation.

You can convert from parametric to 3D with ParametricGlider.get_glider_3d().

Lines and LineSet

The LineSet holds all lines and their attachment points. Line geometry is solved as a linear system; sag can be added. Attachment points reference ribs or cells.

Mesh

A Mesh is a triangulated 3D surface (and optionally lines) generated from a Glider. It can be exported to OBJ (e.g. for CFD or FreeCAD) or other formats.

Plots and patterns

The plots subpackage provides functions to generate cutting patterns, DXF exports, and factory-ready drawings from a glider project.