This study concerns the design of a three components internal aerodynamic cell. It will be used to measure the lift, drag and pitching moment on static or oscillating airfoils enduring air loads. The end objective is to study the unsteady 3 dimensional (3D) air flows interaction with High Aspect Ratio Airfoils (HARAs). This interaction is often characterized by flow recirculation and massive flow separations that lead to reduction of both aerodynamic performance and structure fatigue.In this paper, the Computer-aided design (CAD) of the internal cell is presented. Finite element analysis (FEA), through Ansys software, is used to assess the design before its construction. The result obtained shows the good response of the cell to simulated air loads.