• aerodynamic
• optimization
• PrandltPlane

The present Thesis deals with the application of optimization methods to the preliminary design of a large PrandtlPlane® freighter and with graphical tools to visualize the most interesting configurations. The conceptual design of the PrandtlPlane® freighter has been developed by the Department of Civil and Industrial Engineering – Aerospace Section of the University of Pisa and it is summarized in Chapter 1; the installation of a third lifting surface is described and its effects are foreseen for a large aircraft: improving the maneuverability and the stability is the main aim, without penalizing aerodynamic efficiency and weights. The preliminary study needs a graphical software package (ASD) and an aerodynamic optimizer (AEROSTATE): both of them have been performed using MATLAB® routines. Chapter 2 briefly describes ASD. Local and global optimization methods, together with their implementation in AEROSTATE, are shown in Chapter 3. The aerodynamic solver (AVL) is based on the Vortex lattice Method; despite of its simplicity, the reliability of the results on a PrandtlPlane® configuration has been proved in previous studies: thus, this method is the compromise between accuracy and computational simplicity. AEROSTATE provides results as MATLAB® structured variables and they are transferred to ASD by means INTERFACE, a MATLAB® environment that is developed in this thesis and it is presented in Chapter 4. In Chapter 5, analyses and results are shown: sensitivity studies have been made to the front wing loading, to the rear wing loading, to the bulks length, to the wingspan and to the fins height. The purpose of these studies is to understand how the designer can improve the aerodynamic efficiency in cruise and to obtain a feasible structure. Finally, Chapter 6 explains that many configurations, with different wings arrangements, satisfy low speed constraints, i.e. the landing is possible with low angles of attack, and the trim conditions on the longitudinal plane are met, when flaps and slats are deflected, by means suitable elevators. Conclusions and future developments are collected at the end of this paper.