A New Flap Pressure Distribution with the Center of Pressure Closer to the Main Wing

A new flap pressure distribution with the center of pressure closer to the main wing is presented for enhancement of the lift capability on an HLD configuration. The HLD has such an aerodynamic characteristics that the aft element may induce an additional flow velocity over the main wing due to its formation of a pressure distribution and thus of vorticity with some strength and the associated circulation. The influence of the aft flap on the main wing was quantified by the potential flow theory of conformal transformation and a 2D wind tunnel test was carried out for validation of the effect of the pressure distribution with the center of pressure closer to the main element on some practical aerofoils. As a result of the tests, more lift was obtained than the conventional one which used to be a type of maximum lift loading over the flap.