How to Convert Airfoil Coordinates into CAD Sketches for Wing Design

The sketch is a scaled, placed copy

Analysis wants unit chord. CAD wants millimetres or metres in the airplane’s coordinate system. Start from the cleaned, normalized file so you are not also fairing the scan inside the CAD kernel. Scale by the local chord of that wing station. Place the sketch in a plane at that station. A common choice is a plane normal to the quarter-chord or to the leading edge; the loft will be wrong if each station uses a different convention. Put the leading edge and the trailing edge on named points so twist has a hinge.

Curve, not a cloud of lines

1. Import the scaled points in order, upper and lower still identified.
2. Fit a spline through the cosine-spaced set. Do not explode every digitizer point into its own line segment if a spline through a resampled subset matches the source within your thickness tolerance.
3. Close the trailing edge explicitly. A sharp edge is one point shared by both surfaces. A blunt edge is a short line whose height is the trailing-edge thickness you analysed. Leaving a gap “for the mesher” creates a gap in the wing skin.
4. Constrain the chord line horizontal in the sketch before you apply twist. Twist is a feature of the wing, not a crooked import.
5. Measure maximum thickness and leading-edge radius in CAD and compare them with the unit-chord file times the chord. A mismatch means the spline left the points or the scale was applied twice.

What routinely goes wrong

The sketch is done when a section cut through it reproduces the analysis geometry at the stated chord. The coordinate-format lesson is the file side of this page. The last lesson in the series is the loft that uses more than one of these sketches.

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Where this sits in the series

In simple words: what this page is for

A CAD sketch of an airfoil is the normalized section, scaled to the real chord, drawn in a plane normal to the leading edge or the spar, and closed on purpose.

This lesson exists because section decisions fail when geometry, method labels and selection reasons are scattered. How to Convert Airfoil Coordinates into CAD Sketches for Wing Design helps you keep a clean trail from shape to polar to choice.

Why the topic matters

Engineers lose time when a title sounds clear but the page only sketches the idea. This article expands How to Convert Airfoil Coordinates into CAD Sketches for Wing Design so you can answer three questions without jargon: what is the idea, when do you use it, and how do you check it in a HENDOI product.

Read the sections above for the core definitions. Use the steps below to move from reading into a real project trail you can share with a teammate.

How to apply this in HENDOI

In practice: create a HENDOI account or log in, open HENFOIL, bring a section in (create, import DAT, or digitize), pass the geometry gate, climb the analysis ladder only as far as the decision needs, then compare and archive. Every calculated number should keep its method label.

When the section choice is ready for the aircraft, continue in HENSYNTH for mission, compliance and trades. Same account. Same plans.

What this page will not claim: a teaching polar or geometry note is not a flight-Re certificate. HENFOIL labels methods so you know what you bought. Tunnel data and professional judgement still sit outside any single software run.

Checklist before you leave this page

• Can you state the idea of How to Convert Airfoil Coordinates into CAD Sketches for Wing Design in one sentence?
• Do you know which product owns the next action — HENFOIL or HENSYNTH?
• Will every number you keep carry a method label or a stored-run source?
• If you are new here, have you opened Register or Login?

Related reading on this site

• Active Flow Control on Airfoils: Suction, Blowing and Synthetic Jets
• What Is the Aerodynamic Center of an Airfoil? Location, Meaning and Applications
• How to Identify Numerical Convergence Problems in Airfoil Analysis
• How to Build an Airfoil Analysis Database with Consistent Simulation Conditions
• All HENDOI blog articles
• HENFOIL product page
• HENSYNTH product page
• Pricing — Student, Professional & Team
• FAQ
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• Previous: Build an airfoil database
• Next: Multi-condition airfoil performance maps
• Index: all HENFOIL airfoil lessons

These pages teach the ideas. They are not wind-tunnel data and not a certification analysis. When a number matters, compute it at a stated Reynolds number, Mach number and transition setting, and keep the method label on the result. In HENFOIL that production polar is a VIC polar — see the analysis ladder and the polar field guide.