NACA 6409 Airfoil

The NACA 6409 is a thin, highly cambered high-lift airfoil: only 9% thick but with a strong 6% camber at 40% of the chord. That heavy camber gives a lot of lift at low speeds, which is why it is popular for model aircraft, free-flight gliders, UAVs and propeller sections — wherever high lift at low Reynolds number matters more than low drag.

Cross-section (chord line dashed) · computed from the NACA 4-digit equations

Max thickness

9% c

Max camber

6% c

Camber position

40% c

Trailing edge

sharp

What the numbers mean

In the code 6409, the first digit 6 is the maximum camber as 6% of the chord, the second digit 4 is the position of that maximum camber at 40% of the chord back from the leading edge, and the last two digits 09 are the maximum thickness as 9% of the chord.

Aerodynamic characteristics

The 6% camber lifts the curve a long way up: the section makes strong positive lift at zero angle of attack and carries a large nose-down pitching moment. Being thin and highly cambered it reaches high lift early but stalls sooner and more sharply than a lower-camber section.

Property	Typical value
Zero-lift angle α₀	≈ -6.2°
Lift coefficient at 0°	≈ 0.69
Lift-curve slope	≈ 0.11 /deg
Max lift coefficient C_l,max	≈ 1.5–1.6
Stall angle	≈ 12–14°
Pitching moment C_m,c/4	≈ -0.16

Conditions: Reynolds number Re = 1×10⁶, low speed (Mach ≤ 0.15), smooth surface. Values are representative figures from thin-airfoil theory and published XFoil / wind-tunnel data, rounded for reference.

Want exact numbers for your conditions? These are typical reference values. Open NACA 6409 in the interactive explorer to compute its lift, drag, moment and polar curves live at any Reynolds number and angle of attack.

Where it's used

Model aircraft and free-flight gliders — high lift for slow, floaty flight.
UAVs and small unmanned aircraft — good lift at low Reynolds numbers.
Propeller and fan sections — high camber for loaded blade elements.
High-lift low-speed wings — where maximum lift leads the design.

Coordinates

Surface coordinates as fractions of the chord (x/c, y/c), generated from the standard NACA 4-digit equations with a closed trailing edge. For the full high-resolution coordinate file, use the DAT export inside the explorer.

x/c (upper)	y/c (upper)	x/c (lower)	y/c (lower)
0.000	+0.0000	0.000	+0.0000
0.019	+0.0258	0.030	-0.0116
0.088	+0.0589	0.103	-0.0084
0.219	+0.0920	0.230	+0.0049
0.388	+0.1038	0.389	+0.0162
0.547	+0.0938	0.543	+0.0192
0.720	+0.0691	0.714	+0.0174
0.848	+0.0421	0.843	+0.0118
0.931	+0.0206	0.928	+0.0061
0.982	+0.0055	0.982	+0.0016
1.000	-0.0000	1.000	+0.0000

Explore NACA 6409 in the interactive tool →

See the 3D wing, live Cl / Cd / L-D polar charts, and change the airfoil, angle of attack and Reynolds number in real time.

Open the explorer →

Frequently asked questions

What is the NACA 6409 airfoil?

NACA 6409 is a thin, highly cambered NACA 4-digit airfoil with 6% camber at 40% chord and 9% maximum thickness, used for high-lift low-speed applications like models, UAVs and propellers.

What do the digits in NACA 6409 mean?

The 6 is 6% maximum camber, the 4 is the camber position at 40% of the chord, and the 09 is 9% maximum thickness.

Why does NACA 6409 make so much lift?

Its large 6% camber shifts the lift curve well up, so it carries strong positive lift even at zero angle of attack — useful at the low speeds models and UAVs fly at.

What is the trade-off with NACA 6409?

The heavy camber brings a large nose-down pitching moment and, being thin, an earlier and sharper stall than lower-camber sections.

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