AERODYNAMIC OPTIMISATION AND STABILITY ANALYSIS OF SOLAR- POWERED UNMANNED AERIAL VEHICLE Aun Haider Bhutta 1 1 Assistant Professor, Institute of Aeronautics and Avionics, Air University, Islamabad, Pakistan, Ph. +92(0)321 6906109, Email: aunbhutta@gmail.com. ABSTRACT 47 NED UNIVERSITY JOURNAL OF RESEARCH - APPLIED SCIENCES, VOL XX, NO. 4, 2023 https://doi.org/10.35453/NEDJR-ASCN-2023-0016 Manuscript received on 28th June 2023, revised on 26th October 2023 and accepted on 30th October 2023 as per publication policies of NED University Journal of Research. All rights are reserved in favour of NED University of Engineering and Technology, Karachi, Pakistan. Pertinent discussion including authors’ closure will be published in September 2024 issue of the Journal if the discussion is received by 30th April 2024. Solar-powered unmanned aerial vehicles (UAVs) with long endurance can be utilised for area surveillance as the regenerative nature of solar energy makes such UAVs a terrestrial satellite with 24/7 endurance. This paper presents an aerodynamic optimisation scheme for UAVs through the selection of airfoils and wing planform during the preliminary design phase. Sizing of the tail and control surface based on historical trends for similar aircraft is also substantiated. Finally, detailed aerodynamic and stability analyses of the optimised configuration validate adequate flying and handling qualities of UAVs. The optimisation effort increased the endurance factor by 19.75 percent. This increase will conserve the energy required to overcome in-flight drag and surplus power that can be utilised by onboard equipment. Keywords: solar-powered UAV, aerodynamic analysis, stability analysis, airfoil selection, taper ratio, taper location. 1. INTRODUCTION There has been a series of terrorist attacks on gas pipelines, railway tracks and transmission towers in areas of Baluchistan and Sindh in Pakistan [1]. To prevent such damage and safeguard human lives, the security of critical infrastructure in disrupted areas is required [2]. Solar-powered unmanned aerial vehicle (UAV) with onboard surveillance equipment can be used to monitor such venerable areas [3]. Although solar-powered long-endurance UAVs are a cost- effective solution [4], such mission objectives can only be achieved through extended flight time/endurance and payload capabilities (weight and power consumption) [5].