In the on-going search for improvements in high lift device performance, the field of flow separation control has seen explosive growth in recent years. This is due to a continuously improved understanding of fluid mechanics, the development in experimental and computational techniques and the variety of flow control mechanisms existing today. These multiple mechanisms can be differentiated into active and passive flow control techniques. In this research two passive flow separation control methods are tested on their ability to postpone flow separation on an airfoil with trailing edge flap model of the Extra EA-400. The two methods are the application of vortex generators on the airfoil and the positioning of vortex producing cylinders in the slot of the airfoil flap system.