NACA 5-Digit Airfoils Explained: Designation, Geometry and Aerodynamic Characteristics

How to read five digits

NACA 23012 is not a 4-digit code with an extra character. The digits are a different instruction:

NACA 23112 is the reflexed cousin of 23012: same design lift and thickness target, with the third digit asking for a camber line that reflexs near the trailing edge so the quarter-chord moment is nearly zero. That is a different mean line, not a small edit of 23012.

The standard mean line is not the 4-digit parabola

For the non-reflexed family the camber is strong over the front of the chord and the rear portion is a straight line to the trailing edge. The construction uses two tabulated constants, m and k1, which are not the same as the 4-digit m and p. For the common positions:

Ahead of x = m the camber line is a cubic. Behind x = m it is the straight line yc = (k1 m³ / 6) (1 − x). The constant m in this table is not the x of maximum camber. For 23012, m = 0.2025 while the crest is at 0.15. Using m as if it were p is the usual mistake.

What the aerodynamics are for

The series was drawn to reach a useful design lift with the camber forward, so the pitching moment about the quarter-chord stays milder than a 4-digit section asked to carry the same design lift. NACA 23012 became a common light-aircraft wing section for that reason. The cost is a pressure peak that can be sharper, and a stall that is not automatically gentle, especially once the leading edge is rough or the Reynolds number is low. Read it as a camber design, then compute it at your Reynolds number. The name already told you the design lift is 0.3. It did not tell you CLmax.

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Where this sits in the series

In simple words: what this page is for

A 5-digit NACA name puts the camber farther forward than a 4-digit section of similar design lift. NACA 23012 means a design lift coefficient of 0.3, maximum camber at 15% chord, and 12% thickness.

This lesson exists because section decisions fail when geometry, method labels and selection reasons are scattered. NACA 5-Digit Airfoils Explained: Designation, Geometry and Aerodynamic Characteristics 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 NACA 5-Digit Airfoils Explained: Designation, Geometry and Aerodynamic Characteristics 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 NACA 5-Digit Airfoils Explained: Designation, Geometry and Aerodynamic Characteristics 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

• Airfoil Parameterization Methods: NACA Equations, CST and Spline-Based Geometry
• How to Compare NACA 0012, NACA 2412 and NACA 4412 Airfoil Profiles
• NACA 0015 vs NACA 0018: Comparing Symmetric Airfoil Profiles
• NACA 23012 Airfoil: Design Features, Lift Characteristics and Applications
• All HENDOI blog articles
• HENFOIL product page
• HENSYNTH product page
• Pricing — Student, Professional & Team
• FAQ
• Login · Register now

• Previous: Calculate the NACA mean camber line
• Next: NACA 6-series airfoils
• 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.