liminfoAirfoil Database
Free reference guide: Airfoil Database
About Airfoil Database
The Airfoil Database is a searchable reference covering the most important airfoil profiles used in aerospace engineering, from classic NACA 4-digit and 5-digit series to specialized high-lift, laminar-flow, and supercritical designs. It provides key aerodynamic parameters including maximum lift coefficient (Cl_max), minimum drag coefficient (Cd_min), design lift coefficient, camber percentages, thickness ratios, and optimal Reynolds number ranges for each profile.
This reference organizes airfoil data into six categories: NACA 4-Digit profiles (0012 symmetric, 2412 general-purpose, 4412 high-camber, 0006 thin high-speed, 6412 high-lift), NACA 5-Digit series (23012 and 23015 for general aviation), High-Lift designs (Clark Y flat-bottom, Eppler 387 low-Re, Selig S1223 high-Cl, multi-element slat+flap, Gurney flap), Supersonic airfoils (NASA SC(2)-0714 supercritical, NACA 0010-35 diamond), Aerodynamic Characteristics (Cl, Cd, Cm, L/D, Re, stall), and Design tools (XFOIL analysis, inverse design, Whitcomb area rule).
Each entry includes the airfoil designation, key performance numbers, and practical notes on applications. Whether you are selecting an airfoil for a UAV wing operating at Re=200,000, choosing a general-aviation profile with good stall characteristics, understanding the drag-divergence benefits of supercritical sections for transonic transport aircraft, or setting up an XFOIL session for pressure distribution analysis, this database provides the essential data for informed airfoil selection and preliminary aerodynamic design.
Key Features
- NACA 4-digit airfoil profiles including 0012 (symmetric baseline), 2412 (standard GA), 4412 (high camber), 0006 (thin high-speed), and 6412 (maximum lift) with thickness and camber data
- NACA 5-digit series (23012, 23015) with design lift coefficients and structural thickness advantages for light aircraft wing design
- High-lift airfoil collection including Clark Y (flat lower surface), Eppler 387 (low Reynolds number), Selig S1223 (Cl_max above 2.2), multi-element configurations, and Gurney flaps
- Supercritical and supersonic airfoil data for NASA SC(2)-0714 (transonic drag divergence delay) and NACA 0010-35 (diamond wedge for M > 1.5)
- Aerodynamic coefficient definitions for Cl (lift), Cd (drag breakdown into friction, pressure, induced), Cm (pitching moment at c/4), L/D ratio, and Reynolds number flow regime effects
- Design tool references for XFOIL panel-method analysis, inverse design from target pressure distributions, and Whitcomb area rule application for transonic drag reduction
- Stall behavior documentation including flow separation mechanisms, buffet onset indicators, and recovery techniques for each airfoil category
- Category filtering across NACA 4-Digit, NACA 5-Digit, High Lift, Supersonic, Characteristics, and Design sections for targeted airfoil comparison
Frequently Asked Questions
What do the four digits in a NACA 4-digit airfoil mean?
In NACA XYZZ, the first digit X is the maximum camber as a percentage of chord, the second digit Y is the location of maximum camber in tenths of chord, and the last two digits ZZ are the maximum thickness as a percentage of chord. For example, NACA 2412 has 2% camber at 40% chord with 12% thickness. NACA 0012 is symmetric (0% camber) with 12% thickness.
Which airfoil is best for a low-speed UAV or drone?
For low Reynolds number operation (Re 60,000-300,000 typical for small UAVs), the Eppler 387 offers an excellent Cl/Cd ratio. For maximum lift at low speed, the Selig S1223 achieves Cl_max above 2.2 at Re=200,000 with its high-camber design. The specific choice depends on your speed range, payload requirements, and whether you prioritize endurance (high L/D) or short takeoff (high Cl_max).
What is a supercritical airfoil and why is it used on transport aircraft?
A supercritical airfoil like the NASA SC(2)-0714 has a flattened upper surface that reduces the strength of shock waves at transonic speeds, delaying drag divergence to higher Mach numbers. The lower surface has increased camber to compensate for lift. This allows commercial aircraft to cruise at higher speeds (M 0.78-0.85) without the sharp drag rise that conventional airfoils experience, directly improving fuel efficiency.
What is the Reynolds number and why does it matter for airfoil selection?
The Reynolds number Re = rho*V*c/mu characterizes the flow regime around the airfoil, where rho is air density, V is velocity, c is chord length, and mu is dynamic viscosity. Low Re (below 500,000) flows have significant laminar-to-turbulent transition effects that dominate performance. An airfoil that performs well at Re=3 million (full-scale aircraft) may have poor characteristics at Re=100,000 (model aircraft). Always match airfoil data to your operating Re range.
How does the Clark Y airfoil compare to NACA profiles?
The Clark Y is a classic general-purpose airfoil with 11.7% thickness and 3.4% camber, notable for its flat lower surface which simplifies manufacturing and angle-of-incidence measurement during construction. It delivers good all-around performance comparable to NACA 2412 but is especially popular in experimental and homebuilt aircraft due to its ease of fabrication. Its stall characteristics are gentle and predictable.
What is XFOIL and how is it used for airfoil analysis?
XFOIL is a panel-method airfoil analysis program developed by Mark Drela at MIT. It can compute pressure distributions, boundary layer characteristics, lift/drag polars, and transition locations for subsonic airfoils. You load an airfoil (e.g., NACA 2412), enter OPER mode, set angle of attack with ALFA, and view results with CPV (pressure coefficient) or PPLO (polar plot). It handles viscous effects through an integral boundary layer formulation coupled to the inviscid panel solution.
What is a multi-element airfoil and how much extra lift can it generate?
A multi-element airfoil combines a leading-edge slat, main element, and trailing-edge flap to achieve very high Cl_max values of 3.5-4.0, roughly double that of a single-element airfoil. The slat delays leading-edge stall by re-energizing the boundary layer, while the flap increases effective camber and wing area. This is the technology used in commercial aircraft takeoff and landing configurations and is also analyzed for high-performance STOL designs.
What is a Gurney flap and when is it beneficial?
A Gurney flap is a small perpendicular tab (1-2% chord height) attached to the trailing edge lower surface. It increases Cl by 0.2-0.4 with only a modest drag penalty by modifying the Kutta condition and increasing effective camber. It is widely used in race cars, wind turbine blades, and as a retrofit lift enhancement device. The simplicity of installation makes it attractive when a full airfoil redesign is not practical.