How to Generate Airfoil Coordinates and Export DAT, CSV and CAD Profiles

The shape is the coordinate list

Once you leave a named generator, an airfoil is a polyline. Each point is an x along the chord and a y off it. Analysis codes, meshing tools and CAD kernels all consume that list, and they do not agree about order, units or whether the trailing edge is one point or two. Most “the import looks wrong” bugs are conventions, not aerodynamics.

Normalize before you scale

• Put the leading edge at x = 0 and the trailing edge at x = 1. Chord is 1 in these units. This is the file you archive and the file you analyse.
• Rotate so the chord is on the x-axis. A section imported from a photo at a random angle is not at angle of attack zero; it is just crooked.
• Decide the trailing edge. A single shared point is a sharp edge. Two points with a small gap are a blunt edge. Mixing them inside one file produces a spike that a panel code will treat as a third surface.
• Keep point order monotonous. Upper surface from trailing edge to leading edge, then lower surface from leading edge back to the trailing edge, is the Selig convention used across the UIUC airfoil library. Lednicer format states the two surfaces separately, each from leading edge to trailing edge, with counts on the first lines.
• Scale to millimetres or metres only when you enter CAD or a structural tool. Do the aerodynamics on the unit chord, and apply the real chord in the Reynolds number, not by editing the file twice.

Formats you will actually meet

Generating coordinates

A NACA 4-digit equation, a CST parameterization or a PARSEC set will write a clean list if you ask for enough points near the leading edge, where curvature is highest. Uniform spacing in x under-resolves the nose and over-resolves the flat mid-chord. Cosine spacing (clustered at the leading and trailing edges) is the usual fix. One hundred to two hundred points is plenty for a panel method; a CAD loft may want a fitted spline through fewer, well-placed points rather than a polyline of thousands of digitizer samples.

If the section came from a scanned drawing, expect camber and thickness errors on the order of the line width you traced. Fair the coordinates, then check thickness and camber against what you think you traced. HENFOIL’s digitize path and the DAT import guide are the product side of this page: get a clean unit-chord file, pass the geometry gate, and only then export a scaled profile or a loft for the people downstream.

A checklist before you send a file

1. Chord from 0 to 1, leading edge at the origin, chord on the x-axis.
2. No duplicated points except a deliberate trailing-edge pair.
3. Upper and lower surfaces labelled by order or by a column.
4. Units stated if the file is no longer unit-chord.
5. A one-line note of the generator, the spacing and the trailing-edge policy, so the next person does not “fix” a blunt edge into a spike.

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Where this sits in the series

In simple words: what this page is for

A section is a list of x and y. The file format, the order of the points, and the chord scaling decide whether the next tool sees the shape you designed.

This lesson exists because section decisions fail when geometry, method labels and selection reasons are scattered. How to Generate Airfoil Coordinates and Export DAT, CSV and CAD Profiles 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 Generate Airfoil Coordinates and Export DAT, CSV and CAD Profiles 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 Generate Airfoil Coordinates and Export DAT, CSV and CAD Profiles 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
• Login · Register now

• Previous: How to design an airfoil for long-endurance UAVs
• Next: How thickness and camber affect lift, drag and structure
• 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.