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112 lines
3.7 KiB
ReStructuredText
112 lines
3.7 KiB
ReStructuredText
#############################################
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Tutorial: Spitfire Wing with Gordon Surface
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#############################################
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In this advanced tutorial we construct a Supermarine Spitfire wing as a
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:meth:`~topology.Face.make_gordon_surface`—a powerful technique for surfacing
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from intersecting *profiles* and *guides*. A Gordon surface blends a grid of
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curves into a smooth, coherent surface as long as the profiles and guides
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intersect consistently.
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.. note::
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Gordon surfaces work best when *each profile intersects each guide exactly
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once*, producing a well‑formed curve network.
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Overview
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========
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We will:
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1. Define overall wing dimensions and elliptic leading/trailing edge guide curves
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2. Sample the guides to size the root and tip airfoils (different NACA profiles)
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3. Build the Gordon surface from the airfoil *profiles* and wing‑edge *guides*
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4. Close the root with a planar face and build the final :class:`~topology.Solid`
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.. raw:: html
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<script type="module" src="https://unpkg.com/@google/model-viewer/dist/model-viewer.min.js"></script>
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<model-viewer poster="_images/spitfire_wing.png" src="_static/spitfire_wing.glb" alt="A tea cup modelled in build123d" auto-rotate camera-controls style="width: 100%; height: 50vh;"></model-viewer>
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Step 1 — Dimensions and guide curves
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====================================
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We model a single wing (half‑span), with an elliptic leading and trailing edge.
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These two edges act as the *guides* for the Gordon surface.
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.. literalinclude:: spitfire_wing_gordon.py
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:language: build123d
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:start-after: [Code]
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:end-before: [AirfoilSizes]
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Step 2 — Root and tip airfoil sizing
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====================================
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We intersect the guides with planes normal to the span to size the airfoil sections.
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The resulting chord lengths define uniform scales for each airfoil curve.
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.. literalinclude:: spitfire_wing_gordon.py
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:language: build123d
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:start-after: [AirfoilSizes]
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:end-before: [Airfoils]
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Step 3 — Build airfoil profiles (root and tip)
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==============================================
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We place two different NACA airfoils on :data:`Plane.YZ`—with the airfoil origins
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shifted so the leading edge fraction is aligned—then scale to the chord lengths
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from Step 2.
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.. literalinclude:: spitfire_wing_gordon.py
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:language: build123d
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:start-after: [Airfoils]
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:end-before: [Profiles]
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Step 4 — Gordon surface construction
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====================================
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A Gordon surface needs *profiles* and *guides*. Here the airfoil edges are the
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profiles; the elliptic edges are the guides. We also add the wing tip section
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so the profile grid closes at the tip.
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.. literalinclude:: spitfire_wing_gordon.py
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:language: build123d
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:start-after: [Profiles]
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:end-before: [Solid]
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.. image:: ./assets/surface_modeling/spitfire_wing_profiles_guides.svg
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:align: center
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:alt: Elliptic leading/trailing guides
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Step 5 — Cap the root and create the solid
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==========================================
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We extract the closed root edge loop, make a planar cap, and form a solid shell.
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.. literalinclude:: spitfire_wing_gordon.py
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:language: build123d
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:start-after: [Solid]
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:end-before: [End]
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.. image:: ./assets/surface_modeling/spitfire_wing.png
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:align: center
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:alt: Final wing solid
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Tips for robust Gordon surfaces
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-------------------------------
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- Ensure each profile intersects each guide once and only once
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- Keep the curve network coherent (no duplicated or missing intersections)
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- When possible, reuse the same :class:`~topology.Edge` objects across adjacent faces
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Complete listing
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================
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For convenience, here is the full script in one block:
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.. literalinclude:: spitfire_wing_gordon.py
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:language: build123d
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:start-after: [Code]
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:end-before: [End]
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