1 Ninth International Conference on Computational Fluid Dynamics (ICCFD9), Istanbul, Turkey, July 11-15, 2016 ICCFD9-xxxx Numerical Investigation of Winglets Used to Improve the Flying Performance of Unmanned Aerial Vehicle Prof. Ünver Kaynak 1 , Ahmet Buğra Çoban 2 1 Department of Mechanical Engineering, TOBB University of Economics and Technology, Ankara 06520, Turkey 2 Department of Mechanical Engineering, TOBB University of Economics and Technology, Ankara 06520, Turkey Corresponding author: abcoban@etu.edu.tr Abstract: In this study, the aerodynamic forces, velocity and pressure distributions are analyzed on SD7062 wing profile with CFD program FLUENT. Calculations are made for one clean wing and 3 different winglets named End-Plate, Blended and Scimitar which are added on this clean wing. Each model are analyzed for different angle of attack degrees between -5 and 17. After calculations were ended, it is seen that wings’ with winglets aerodynamic performances are increased. Additionally, stall was occurred around 15 aoa degrees. Keywords: Unmanned Aerial Vehicle, Winglet, Numerical Algorithms, Computational Fluid Dynamics, Turbulence Modeling. 1 Introduction Aviation industry is more costly compared to other transport sectors. Every step of the production and design of an aircraft requires a high budget. The flight of the aircraft also reveals high fuel costs. This is the reason that at the aviation industry, economy is one of the most important issues. In many universities and some big companies it is being studied to reduce these costs. When an aircraft is considered, research and development studies are carried out in many areas like power, control, structure and aerodynamics. The aim is primarily to improve the performance of the aircraft as well as saving fuel. Unmanned Aerial Vehicles are today used for many purposes. Because of using different areas, uav became more important. The flying performance like flight duration, distance became important as well. Because of this reason aerodynamic efficiency has become essential. Aerodynamic efficiency can be provided by increasing lift force and reducing drag force. To reduce the drag force it is important to have a smooth wing surface. To increase lift force it can be provided by the two methods. The first is to increase the pressure distribution around the airfoil, and the second is to reduce the thickness of the boundary layer around the wing profile. Various designs and methods have been developed to provide these features. Angle of attack and wing profile’s amount of camber are the factors that affect flight performance. Also with the new parts which are added to design like flaps, slats, slots and winglets, improving aerodynamic performance works are made [1]. Winglet at the wing tip is added nowadays is mostly preferred. First winglet idea was put forward by Hemk in the 1920s. Airfoil tip plate (End-Plate) was investigated by Hemk and how it affects the flight [2]. However, the addition of winglets to the wing tips and realization importance of winglets was