Airfoil analysis library

Theodorsen's potential theory of arbitrary wing sections implemented in Python 3.7.

Generate or otherwise obtain an airfoil .dat file in Selig format*.

Import arbifoil.py

from arbifoil import *

Instantiate a foil object by passing it a .dat airfoil coordinates file.

clarky = foil('airfoils/clarky.txt')

After the mapping is determined, you have at your disposal the following methods for analysis:

• C_L(aoa) - returns the coefficient of lift at specified angle of attack in degrees,
• C_M_AC() - returns the moment coefficient about aerodynamic center,
• C_M_LE(aoa) - returns the moment coefficient about leading edge at specified angle of attack in degrees,
• C_M_1Q(aoa) - returns the moment coefficient about 1 quarter chord point at specified angle of attack in degrees,
• CoP(aoa) - returns nondimensional center of pressure measured from the leading edge,
• AC() - returns the nondimensional coordinates of the aerodynamic center.

Selig format

The points run from the trailing edge across the upper surface of the airfoil to the leading edge and back across the lower surface. For examples, check the arbifoil/airfoils/ folders.

Coordinate system positioning

The origin of the right handed system is at the leading edge.

The x axis points towards the trailing edge.

The upper surface points have positive y values, the lower surface points have negative y values.

[1] Theodorsen, T.: Theory of Wing Sections of Arbitrary Shape, NACA, 1931.

[2] Theodorsen, T., Garrick I.E.: General Potential Theory of Arbitrary Wing Sections, NACA TR-452, 1934.

[3] Karamcheti, K.: Principles of ideal-fluid aerodynamics, R. E. Krieger Publishing Company, 1980.