Using a panel method with distributed sources and vortices on the airfoil surfaces, aerodynamic characteristics are studied for different wing sections operating in ground effect at various angles of attack and ground clearances for steady conditions. The influence of the ground is handled by means of the mirror reflection method. Computational results of NACA 0012 and 4412 out of ground effect are obtained in order to compare with known experimental results. Also some results of this study are compared with the results of other published numerical methods on NACA4412 and 6409 in ground effect. NACA0012, 4412 and 6409 are studied in terms of their lift and moment coefficients and center of pressure variation in ground effect.
Two foci are defined for an airfoil in ground effect: aerodynamic centre in angle of attack, X? and aerodynamic centre in height, Xh. At different angles of attack, the aerodynamic centres are found and their variation with height is observed for NACA4412 and NACA6409. None of these NACA profiles obey to Irodov's stability criterion in any ground clearances. S-shaped airfoils, which are proposed to be used in WIG (Wing In Ground Effect) crafts to increase the longitudinal stability of the wings, are defined with two parameters in the thesis. They have an s-shaped camber line and a NACA standard thickness distribution. By changing these parameters some s-shaped airfoils are obtained to satisfy the Irodov's stability criterion in the flight heights less than half of the chord and to give fairly good lift coefficients.

Thesis Defence