Joined-Wing UAV: From Design to Flight Marshal Deep Kafle 1 , Nikesh Bhattarai 1 *, Hyeon Beom Jo 1 , Kyoung Mu Min 1 , Han Yeong Baek 2 , Byoung Soo Kim 2 , Sung Hun Kim 1 Sacheon Aerospace Manufacturing Ind. Co., Ltd. 1 Gyeongsang National University 2 ABSTRACT Joined-wing UAV, known for its light weight, high stiffness and resistance to bending, better aerodynamic efficiency has been an air vehicle of interest for many researchers. In this paper, two types of configuration of Joined-Wing UAV are designed and the one better suiting the mission objective is further analyzed numerically. Its flight performance is further analyzed for varying weight and wingspan and the design fulfilling the mission requirements is examined. CFD analysis for the full scale model is also performed, followed by static structural analysis of composite structures. Its static and dynamic stability are also numerically studied. The analyses show satisfying results, based on which a half- scaled model is manufactured and flight test is performed to study and determine the control-law structure of the aircraft and to set the control-law design parameter for static performance. The results presented are a basis for the manufacture of full scale UAV. Keywords: Joined-Wing UAV, Flight Performance, CFD, Static Structural Analysis, Control-Law Structure 1. INTRODUCTION Joined-wing aircraft, first patented in the US by Julian Wolkovitch [1] has numerous advantages such as light weight, high stiffness, higher resistance to bending moment, higher aerodynamic efficiency, good stability and control, short take-off distance, etc. [2], [3]. Several studies [4], [5] have been performed, albeit conceptually to evaluate the structural and aerodynamic characteristics of joined-wing aircraft compared to the conventional cantilever wing configuration. Results from [5] show that joined-wing aircraft is as much as 5.07% lighter generating 1.3 times the lift and reducing 3.5% drag than its conventional-wing counterpart. In [6] and [7], the authors discuss the use of joined-wing aircraft to increase airport capacity by means of having reduced wing span and shorter take-off distance, thus producing higher throughput at runway and more space in taxiway. In this work, two different layouts of Joined wing type UAV is designed and studied. The one with a better result is then further analyzed considering CFD, structure and stability. To check control and stability of selected layout, a half scale model equipped with Pitot static tube, Flight Control Computer (FCC), Global Positioning System (GPS) antenna and modem antenna is fabricated and flown. The data collected during the test flight are then analyzed and interpreted. Further future works and improvements to be done are also included in the last section as the detail design and manufacture of final full scale model is still under progress. 2. DESIGN REQUIREMENTS & MISSION The mission specifications for the design under consideration are very critical. The total weight of the aircraft is estimated to be 20 kg and it is to be propelled by high efficient and low-weight brushless motor. Other general design requirements are shown in Table 1 and mission profile is illustrated in Fig. 1. Table 1. General Requirements Parameters Value Range 10 ~ 12 km Cruise Altitude 100 ~300 m Endurance 1.5 hour Max. Weight 20 kg Fig. 1: Mission Profile