Designing wings & aerofoils

A workflow for cutting foam-core wings on cncfoam.com: choosing aerofoils, root-to-tip morph and taper, washout via twist, spar slots, and getting clean, accurate sections.

Wings are the classic hot-wire job, and a foam-core wing is one of the most satisfying things you can cut. Here is a practical workflow.

Pick your aerofoils

Decide the section for the root and the tip. They can be the same (a constant-section wing) or different (a thicker, higher-lift root blending to a thinner tip). The AI generator can produce NACA sections directly, or import your own from an aerofoil tool as SVG/DXF.

Set up the morph

Load a two-part morph with the root profile on the left (X/Y) and tip on the right (U/V), on a 4-axis machine. The cut length along the wire equals the wing span you set as the block Z size. The wire blends root-to-tip in a single ruled-surface pass. See Morphing two profiles.

Taper & washout

  • Taper — scale the tip profile smaller than the root (unlink the Object-bar scale) for a tapered planform.
  • Washout — add a small Rotate UV twist so the tip section sits at a lower angle than the root, which improves stall behaviour.

Watch the cut-speed mismatch

A big, fat root and a tiny tip have very different perimeters, so the root side of the wire travels much farther in the same time. If cncfoam.com warns of a mismatch over ~1.5×, raise the feedrate or keep the root and tip closer in size. See Cut quality.

Cores, sheeting & spars

Foam wings are usually sheeted (covered in thin balsa/ply or laminate) and carry a spar. Plan for these:

  • Cut the core slightly undersize by the sheeting thickness if the finished section must be exact (a kerf/offset trick — see kerf compensation).
  • Keep the off-cuts (the cradle/shucks) — they support the delicate core for sheeting and gluing.
  • Spar slots can be cut as a second pass or added by hand after coring.
Cut both wing panels from one block as a left/right pair so they are mirror-identical. Mark the cradle so the core goes back exactly where it came from.