# NACA 2421 airfoil

> What is the exact shape of the NACA 2421 airfoil, and what do the digits mean?

- Category: Airfoils › NACA 4-digit
- Kind: Standard part
- Basis: Computed from the NACA equations (Report 460 / Report 610, restated in NASA TM-4741)
- Page: https://xemstudio.com/objects/naca-2421-airfoil/ · JSON: https://xemstudio.com/api/geometry?object=naca-2421-airfoil · Plain text: https://xemstudio.com/objects/naca-2421-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 | 21.0 |

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

## Notes

- NACA 2421: 2 % camber at 40 % chord, 21 % thick.
- NACA 4-digit: first digit = maximum camber in % of chord, second = its position in tenths of chord, last two = maximum thickness in % of chord (NACA Report 460).
- Ordinates are in % of chord from the leading edge, computed from the published equations with the closed-trailing-edge thickness coefficient (−0.1036, as in NASA TM-4741). The original reports use an open trailing edge (−0.1015); the difference is under 0.03 % of chord near the trailing edge.
- 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

| x (% chord) | upper x | upper y | lower x | lower y |
|---|---|---|---|---|
| 0 | 0.000 | 0.000 | 0.000 | 0.000 |
| 1.25 | 0.930 | 3.422 | 1.570 | -3.176 |
| 2.5 | 2.073 | 4.798 | 2.927 | -4.314 |
| 5 | 4.458 | 6.666 | 5.542 | -5.728 |
| 7.5 | 6.905 | 8.005 | 8.095 | -6.646 |
| 10 | 9.387 | 9.047 | 10.613 | -7.297 |
| 15 | 14.417 | 10.554 | 15.583 | -8.117 |
| 20 | 19.499 | 11.528 | 20.501 | -8.528 |
| 25 | 24.610 | 12.108 | 25.390 | -8.670 |
| 30 | 29.738 | 12.373 | 30.262 | -8.623 |
| 40 | 40.000 | 12.150 | 40.000 | -8.150 |
| 50 | 50.103 | 11.195 | 49.897 | -7.306 |
| 60 | 60.177 | 9.733 | 59.823 | -6.178 |
| 70 | 70.212 | 7.855 | 69.788 | -4.855 |
| 80 | 80.200 | 5.607 | 79.800 | -3.385 |
| 90 | 90.133 | 2.996 | 89.867 | -1.774 |
| 95 | 95.075 | 1.549 | 94.925 | -0.910 |
| 100 | 100.000 | -0.000 | 100.000 | 0.000 |

## Where the files are

- NACA (NASA Technical Reports Server): [Report 460: The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel (Jacobs, Ward, Pinkerton, 1933)](https://ntrs.nasa.gov/citations/19930091108) — web — Publisher's page; dimensions are facts
- NASA: [TM-4741: Computer program to obtain ordinates for NACA airfoils (Ladson, Brooks, Hill, Sproles, 1996)](https://www.pdas.com/refs/tm4741.pdf) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/naca-2421-airfoil/index.json · license: https://xemstudio.com/files/hardware/naca-2421-airfoil/LICENSE.md

- naca-2421-airfoil-section-100mm-chord: [STEP](https://xemstudio.com/files/hardware/naca-2421-airfoil/naca-2421-airfoil-section-100mm-chord.step) · [STL](https://xemstudio.com/files/hardware/naca-2421-airfoil/naca-2421-airfoil-section-100mm-chord.stl) — NACA 2421 section, 100 mm chord × 20 mm span, closed trailing edge, 160 points from the equations (scale to your chord)

## Questions

**How thick is the NACA 2421?**

Maximum thickness 21.00 % of chord at 30.0 % chord: 21.00 mm on a 100 mm chord.

**Where is the NACA 2421's camber?**

Maximum camber 2.00 % of chord at 40.0 % chord.

**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.

## Fits with

- [NACA 2408 airfoil](https://xemstudio.com/objects/naca-2408-airfoil/)
- [NACA 2410 airfoil](https://xemstudio.com/objects/naca-2410-airfoil/)
- [NACA 2411 airfoil](https://xemstudio.com/objects/naca-2411-airfoil/)
- [NACA 2412 airfoil](https://xemstudio.com/objects/naca-2412-airfoil/)
- [NACA 2414 airfoil](https://xemstudio.com/objects/naca-2414-airfoil/)
- [NACA 2415 airfoil](https://xemstudio.com/objects/naca-2415-airfoil/)