Effect of plain flap on the distribution over the symmetrical aerofoil NACA 66 015. Flap is a sub-control surface that enhances the lift of the aircraft. This paper includes placing of NACA 66-015 aerofoil with trailing edge flaps at a constant Reynolds number. Measurement of coefficient of pressure (Cp) over the aerofoil at different angle of attacks, different flap settings have been done. An investigation on performance of aerofoil with flap has been done to understand the pressure distribution over and below the wing. Laser illuminated smoke visualization have been used to identify flow separation point. It was observed that the stall angle increased and performance of the wing was more enhanced as the angle of attack increased. ANSYS FLUENT analysis to validate experimental results.