The Design Improvement of Airfoil for Flying Wing UAV PRASETYO EDI, NUKMAN YUSOFF and AZNIJAR AHMAD YAZID Department of Engineering Design & Manufacture, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, MALAYSIA p_edi@um.edu.my http://design-manufacturer.eng.um.edu.my/ Abstract: - This paper intends to presents the design improvement of airfoil for flying wing UAV (Unmanned Aerial Vehicle) when the Author works with Universiti Putra Malaysia. The design was performed using XFOIL code (an interactive program for the design and analysis of subsonic isolated airfoils) and the wind tunnel test results for verification. Eppler E334 (thickness to chord ratio, t/c = 11.93%) is used as a based airfoil. The final design was using Eppler E334 with t/c = 13.5%. It was shown from this work that the result from XFOIL is fairly accurate. Key-Words: - airfoil design, flying wing, UAV (Unmanned Aerial Vehicle), aerodynamic design 1 Introduction The importance of UAV in operations and the unprecedented variety deployed today is growing. The UAVs can be used both for military and non- military purposes including coastal surveillance and monitoring of open burning, illegal logging, piracy, the movement of illegal immigrants, agricultural and crop monitoring, search and rescue, weather observations and tracking cellular phones. Indications are that there is a growing market for this type of aircraft. Like most other next-generation aircraft, UAVs will require low-cost and efficient configurations. Many of existing UAV use conventional (i.e. : low/mid/high-wing, fuselage tail and tractor engine) and unconventional (i.e. : flying wing, three- surfaces, low/mid/high-wing, high aspect ratio wing, fuselage tail/canards/inverted V-tail and pusher engine) configurations. The design of low-cost and efficient configurations of UAV becomes increasingly more important for improving the performances, flight characteristics, handling qualities and UAV operations. Most of small UAV fly at low Reynolds number, this allow to uses fuselage-wing-tail with laminar flow technology, to improve its cruise performance. Therefore, the understanding of and ability to design and analyze those configuration and technology [1, 2 & 3] for UAV is a problem that must be solved in order to allow the UAV designer to develop a UAV which satisfy the prescribe design requirements and objectives. However, the presence of unconventional configuration and laminar flow technology seriously complicates design and analysis procedures because of important and often complex interaction between the individual elements of UAV often present very different and distinct challenges. Common people when asked what an airplane looks like and most will answer a tube with wing. But flying wing aircraft is different, flying wing body does not have a conventional aircraft tail, used to control pitch (up and down) and yaw (side to side) motions. Instead it uses a combination of control surface on the trailing edge of the wing to maneuver the airplane. It also does not have a conventional tube type fuselage for payload. All structure, engine and payload are fixed inside the wing. The wing is everything. Figure 1. Flying Wing Unmanned Aerial Vehicle. Flying wing have the advantage of having less air drag, hence increasing the lift over drag coefficient, making it more fuel efficient and environment friendly aircraft. For a same engine and fuel capacity, flying wing will have a better range and WSEAS TRANSACTIONS on APPLIED and THEORETICAL MECHANICS Prasetyo Edi, Nukman Yusoff, Aznijar Ahmad Yazid ISSN: 1991-8747 809 Issue 9, Volume 3, September 2008