# Selig S3021 airfoil

> What is the exact shape of the Selig S3021 airfoil?

- Category: Airfoils › Other airfoils
- Kind: Standard part
- Basis: Coordinates from the UIUC Airfoil Coordinates Database; thickness, camber and section by Xem Studio
- Page: https://xemstudio.com/objects/s3021-airfoil/ · JSON: https://xemstudio.com/api/geometry?object=s3021-airfoil · Plain text: https://xemstudio.com/objects/s3021-airfoil/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 100.0 | 20.0 | 9.47 |

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- Selig S3021: Michael Selig (S series). Maximum thickness 9.47 % of chord at 30.0 % chord; maximum camber 2.96 % of chord at 39.2 % chord.
- Coordinates from the UIUC Airfoil Coordinates Database (M. Selig, UIUC Applied Aerodynamics Group), file s3021.dat, titled 'S3021-095-84'. Thickness and camber are computed by Xem Studio from those points (vertical distance at equal x, linear between points).
- The published trailing edge is sharp, so the section uses it as printed.
- The file is a 100 mm chord section, 20 mm deep: scale it uniformly to your chord, or import the STEP and sweep or loft it into a wing. Thickness scales with chord; the shape is the same at any size.

## Sizes

| parameter | value | source |
|---|---|---|
| Max thickness | 9.47 % chord at 30.0 % chord | computed from the UIUC coordinates |
| Max camber | 2.96 % chord at 39.2 % chord | computed from the UIUC coordinates |
| Published points | 61 (32 upper, 30 lower, shared leading edge) | UIUC coordinates |
| Trailing edge as published | sharp (closed) | UIUC coordinates |
| y at x = 1.25 % chord | upper +1.679 / lower -0.928 % chord | linear between the published points (UIUC coordinates) |
| y at x = 2.5 % chord | upper +2.548 / lower -1.263 % chord | linear between the published points (UIUC coordinates) |
| y at x = 5 % chord | upper +3.753 / lower -1.631 % chord | linear between the published points (UIUC coordinates) |
| y at x = 7.5 % chord | upper +4.643 / lower -1.845 % chord | linear between the published points (UIUC coordinates) |
| y at x = 10 % chord | upper +5.334 / lower -1.975 % chord | linear between the published points (UIUC coordinates) |
| y at x = 15 % chord | upper +6.341 / lower -2.073 % chord | linear between the published points (UIUC coordinates) |
| y at x = 20 % chord | upper +6.982 / lower -2.063 % chord | linear between the published points (UIUC coordinates) |
| y at x = 25 % chord | upper +7.386 / lower -1.988 % chord | linear between the published points (UIUC coordinates) |
| y at x = 30 % chord | upper +7.596 / lower -1.874 % chord | linear between the published points (UIUC coordinates) |
| y at x = 40 % chord | upper +7.498 / lower -1.599 % chord | linear between the published points (UIUC coordinates) |
| y at x = 50 % chord | upper +6.861 / lower -1.304 % chord | linear between the published points (UIUC coordinates) |
| y at x = 60 % chord | upper +5.805 / lower -1.015 % chord | linear between the published points (UIUC coordinates) |
| y at x = 70 % chord | upper +4.494 / lower -0.744 % chord | linear between the published points (UIUC coordinates) |
| y at x = 80 % chord | upper +3.063 / lower -0.493 % chord | linear between the published points (UIUC coordinates) |
| y at x = 90 % chord | upper +1.567 / lower -0.251 % chord | linear between the published points (UIUC coordinates) |
| y at x = 95 % chord | upper +0.768 / lower -0.103 % chord | linear between the published points (UIUC coordinates) |
| Coordinates source | UIUC Airfoil Coordinates Database: s3021.dat ('S3021-095-84') | UIUC Applied Aerodynamics Group (M. Selig) |

## Where the files are

- UIUC Applied Aerodynamics Group (M. Selig): [UIUC Airfoil Coordinates Database: s3021.dat ('S3021-095-84')](https://m-selig.ae.illinois.edu/ads/coord/s3021.dat) — web — UIUC Airfoil Coordinates Database, public research data; coordinates are facts, cited and linked, not rehosted
- UIUC Applied Aerodynamics Group (M. Selig): [UIUC Airfoil Coordinates Database (original: Michael Selig (S series))](https://m-selig.ae.illinois.edu/ads/coord_database.html) — web — UIUC Airfoil Coordinates Database, public research data; coordinates are facts, cited and linked, not rehosted

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/s3021-airfoil/index.json · license: https://xemstudio.com/files/hardware/s3021-airfoil/LICENSE.md

- s3021-airfoil-section-100mm-chord: [STEP](https://xemstudio.com/files/hardware/s3021-airfoil/s3021-airfoil-section-100mm-chord.step) · [STL](https://xemstudio.com/files/hardware/s3021-airfoil/s3021-airfoil-section-100mm-chord.stl) — Selig S3021 section, 100 mm chord × 20 mm span, 60 points from the published coordinates, single trailing-edge point (scale to your chord)

## Questions

**How thick is the Selig S3021?**

Maximum thickness 9.47 % of chord at 30.0 % chord: 9.47 mm on a 100 mm chord (computed from the UIUC coordinates).

**How much camber does the Selig S3021 have?**

Maximum camber 2.96 % of chord at 39.2 % chord (computed from the UIUC coordinates).

**How do I use it for my wing?**

Scale the 100 mm section to your chord (e.g. 180 mm chord = 180 % scale), then extrude or loft between root and tip sections. For a tapered wing, scale a root and a tip copy and loft between them.

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