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A NACA airfoil is a wing cross-section shape defined by the National Advisory Committee for Aeronautics (NACA), the U.S. research body that preceded NASA. The name is followed by a number, such as NACA 2412, and in the four-digit family that number encodes the shape directly: maximum camber, where that camber sits along the chord, and maximum thickness. This guide explains how to read the designations and which original NACA reports to cite for the underlying data.
What a NACA airfoil is
A NACA airfoil is a member of a numbered family of airfoil sections developed and tested by NACA. The U.S. Centennial of Flight Commission notes that in 1933 NACA issued its Technical Report No. 460, a monumental study presenting systematic wind-tunnel results for a large group of related sections. Later families (five-digit, then the 6-series laminar-flow sections) extended the approach.
Who published it and what the reports cover
The primary literature is held in the NASA Technical Reports Server (NTRS). Two reports anchor the topic:
- NACA Technical Report 460 (Jacobs, Ward and Pinkerton, 1933), The characteristics of 78 related airfoil sections from tests in the variable-density wind tunnel. It tested a large group of related airfoils at high Reynolds number and studied systematically the effect of thickness and the form of the mean line.
- NACA Technical Report 824 (Abbott, Von Doenhoff and Stivers, 1945), Summary of Airfoil Data. It reviews the historical development of NACA airfoils and gives pressure-distribution data for the older four-digit and five-digit sections, the derivation of the 6- and 7-series thickness forms, lift, drag, pitching-moment and critical-speed characteristics, high-lift devices, and the effect of surface condition.
When you need numbers rather than a shape description, cite the report and the test conditions, not just the designation. This is the same habit as using a persistent identifier: the NTRS record gives readers a stable place to look.
How to read a NACA designation
Four-digit sections
Per the Centennial of Flight account, the four digits define the overall shape: the first digit is the maximum camber, the second digit is the position of that maximum camber, and the last two digits are the maximum thickness.
Worked example: NACA 2412
The decoding below is arithmetic from that rule, offered as an illustration:
| Digits | Meaning | NACA 2412 |
|---|---|---|
| First | Maximum camber | 2, i.e. 2% of the chord |
| Second | Position of maximum camber | 4, i.e. 40% of the chord from the leading edge |
| Last two | Maximum thickness | 12, i.e. 12% of the chord |
A section with no camber has 00 as its first two digits (for example NACA 0012, 12% thick).
Five-digit sections
The five-digit series appeared in the late 1930s. According to the same source, its second digit counts in twentieths of a chord rather than tenths as in the four-digit series, and the middle digit is 0 for a straight mean camber line or 1 for a curved (reflex) one.
6-series sections
By the end of the 1930s attention had turned to laminar-flow airfoils. The NACA 6-series sections were shaped with maximum thickness far back from the leading edge. Their numbering is not a simple geometric readout, so use the thickness-form derivation in Technical Report 824 rather than guessing at the digits.
Strengths and limits
- Strength: traceable origin. The families come with published, systematic test reports (TR-460, TR-824) that you can cite.
- Strength: readable geometry. For the four-digit family the designation itself states camber, camber position and thickness.
- Limit: test conditions. Published characteristics belong to the tunnel, Reynolds number and surface condition used; TR-824 specifically covers how surface condition affects results.
- Limit: historical data. The reports date from 1933 and 1945. Treat them as the origin of the families and check current design practice before relying on them for a modern application.
- Limit: designation is not performance. A series number does not by itself give lift or drag; those come from the data in the reports.
Alternatives: the NACA families compared
| Family | Period | What the sources say |
|---|---|---|
| Four-digit | Reported 1933 (TR-460 era) | Digits give maximum camber, its position and maximum thickness |
| Five-digit | Late 1930s | Second digit in twentieths of chord; middle digit 0 = straight, 1 = reflex mean line |
| 6-series | End of 1930s onward | Laminar-flow sections with maximum thickness far back from the leading edge |
| 7-series | Covered in TR-824 (1945) | TR-824 covers the derivation of the 6- and 7-series thickness forms |
FAQ
What does NACA stand for?
National Advisory Committee for Aeronautics, the U.S. body that preceded NASA.
What does NACA 2412 mean?
Under the four-digit rule: 2% maximum camber, located at 40% of the chord, with 12% maximum thickness.
Where do I find the original data?
In the NASA Technical Reports Server: Technical Report 460 for the 78 related sections and Technical Report 824 for the summary of airfoil data (links below).
How should I document an airfoil choice in a paper?
Name the designation, cite the report, and state the conditions the data apply to so others can repeat the work. See methods reproducibility and reproducible research practices.
Sources
- Jacobs, E. N., Ward, K. E., Pinkerton, R. M. (1933). NACA TR-460. NASA NTRS record. Read 2026-11-07.
- Abbott, I. H., Von Doenhoff, A. E., Stivers, L. S. (1945). NACA TR-824, Summary of Airfoil Data. NASA NTRS record. Read 2026-11-07.
- U.S. Centennial of Flight Commission, airfoils essay. centennialofflight.net. Read 2026-11-07.
