Development of a Long Endurance Mini-UAV:ETERNITY

This study presents the effort given for the first prototype of a Long Endurance Mini UAV concept called Eternity. A multi-disciplinary conceptual aircraft design program called CDSGN is developed and used for the design of the Eternity. Unlike the traditional design methods that uses statistical data from the previous well-flown aircrafts, CDSGN analyses numerous aircraft candidates and simulates each candidate for the given mission definition and outputs the corresponding performance. The unique property of the presented design methodology comes from a computationally fast and physically accurate modelling of the aerodynamic characteristics of each candidate by using a modified version of a vortex lattice program called AVL from Mark Drela. Two types of configurations have been analysed for the Eternity design, conventional and flying-wing. Awide envelope of variable design parameters used for both configurations such as wing surface area, cruise speed, battery capacity, different airfoils, etc... Integration of solar cells, and the management of solar energy is also considered for every candidate. Only the wing span size has been limited to one meter. Additionally, the on-board avionics and payload weights and sizes are fixed for every candidate as they are independent of the design. Analyses by CDSGN concluded the dominance of the conventional configuration for the given long endurance mission performance both on solar and nonsolar conditions. Optimum wing surface area and the on-board battery energy found interactively by a post-filtering program developed in-house. A custom airfoil family, transitioning along the span, have been designed specifically for the corresponding local Reynolds number for specific spanwise locations. A wind-tunnel campaign is performed with a full-scale model and first flight tests have been performed in order to show the feasibility of long endurance flights.