Of these, profiles NACA type are well known, and in some commonly used as practice for the validation of numerical methods. Note, for example, Joukowski, Eppler, Wortmann, NACA, RAE, Göttingen, NLR, NASA / LRC and SANDIA profiles. On the same figure shows the aerodynamic forces L (lift) and D (drag).ĭifferent types of airfoils are cataloged in the world.the arch is on the order of 6 to 8% and d / e max varies from 15 to 50%.

Conventional profiles has a relative thickness of 6 to 20% approximately located at C / 3 The expression e max / c = t is the maximum relative thickness.

the maximum value of the MN segment represents the maximum thickness of the profile, e max.

We denote by f the greatest ordinate of the mean camber line over AB.

The mid-perpendicular to the reference chord segments, such MN is called the profile or skeleton mean camber line.

APB = camber line profile compared to the speed of the flow, Vinfini.

d = the maximum position of the profile camber.

a = angle attack (or geometric incidence ).

D = drag force paralelle resistant to fluid displacement expressed in newtons.

L = lift force perpendicular to the displacement of the fluid expressed in newtons.

The shape of the profile is an essential feature of a wing and greatly affects the aerodynamic characteristics and performance of an aircraft.Īccording to the figure above, we define the following geometric quantities of an airfoil One defines an airfoil as the geometric shape that is obtained by the vertical section of an airplane wing.

between the tube and the sheet we have the airfoil. Make it fly a tube is fairly complicated (although this is possible by rotating it but we'll talk about later), and to collect the necessary thrust to propel a boat with a sheet of paper is quite complicated too. įrom the point of view of mechanical strength to the best performing weight / resistance is the tube. A slight bend for lift and our sheet s' flies away effortlessly. In the aerodynamic or hydrodynamic point of view, the higher the profile is fine unless it generates a resistance to the advancement. The compromise between performance and mechanical strength is at the heart of the problem of the definition and optimization of the geometry of the wing or blade. The profile shape of the wings or blades determine their aerodynamic or hydrodynamic performance but also their mechanical strength.

Airfoil blade