= NACA 0012
{c}
<NACA 0012> is a <NACA four-digit airfoil> with zero specified <airfoil camber> and nominal maximum <airfoil thickness-to-chord ratio> $0.12$. Its upper and lower thickness envelopes are reflected across the <airfoil chord>, making it a <symmetric airfoil>. The designation describes section geometry; it is not a measured lift or drag specification.<Applied Computational Aerodynamics by W. H. Mason>[Appendix A.1, four-digit naming rule and equation (A-4)]{ref}
To construct it, set the <airfoil mean camber line> to zero directly and use the standard thickness envelope in <trailing edge> with $\eta=0.12$. No mean-line location parameter is needed. For the finite-edge convention, the normalized half-thickness at $x/c=0.5$ is $y_t/c\approx0.052940252$. An original section with $c=0.30\,\mathrm m$ therefore has surface heights $\pm15.8821\,\mathrm{mm}$ at that station and full local thickness $31.7642\,\mathrm{mm}$. The nominal maximum thickness is about $36\,\mathrm{mm}$; twelve percent is not the thickness at every station.
Its nose-radius formula is $r_{\rm LE}/c\simeq1.1019(0.12)^2$. The same $0.30\,\mathrm m$ chord gives $r_{\rm LE}\simeq4.7602\,\mathrm{mm}$. The finite-edge polynomial also leaves a small nonzero rear gap; closing that endpoint changes the coordinate specification. These are consequences of the stated construction, not independent manufacturing measurements.
A useful physical test records <pressure> and section <lift> while varying <angle of attack> at controlled <Reynolds number>. <Thin airfoil theory> predicts a zero <zero-lift angle of attack> for the symmetric ideal model, but it does not supply a universal <aerodynamic stall> angle. The original NACA experimental programme systematically compared related shapes in a <variable-density wind tunnel>, providing a reason to identify both the section and the flow conditions when citing results.<The Characteristics of 78 Related Airfoil Sections from Tests in the Variable-Density Wind Tunnel by Eastman N. Jacobs and others>[Summary and profile-family investigation]{ref}
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