Development of design tools and methods for box-wing airplanes and application of the PrandtlPlane concept to a short-medium range aircraft

This dissertation focuses on the study of the innovative PrandtlPlane aircraft. The PrandtlPlane is the application in aeronautical engineering of an unconventional aerodynamic concept based on the Best Wing System theory, postulated by Prandtl one century ago; the lifting system of this configuration is a box-wing properly designed to minimise induced drag. The study of this configuration aims to evaluate the impact of its utilisation in the air transport system of the future; in particular, the focus is on the main air transport challenges expected in the next years, such as the need to drastically reduce pollutant emissions, to satisfy a huge increase in air traffic demand, and to alleviate airport congestion problems at the same time. The thesis has been conducted in the framework of PARSIFAL project, funded by the European Community in the Horizon2020 program. The Thesis is mainly divided into two parts. In the first part, tools and methods for conceptual design of PrandtlPlane aircraft are described; the application of these design procedures has been useful to identify conceptual design guidelines. These design indications have been used to initialize a specific design process, described in the second part of the Thesis. The second part describes the application of the PrandtlPlane concept to short-medium range commercial transport aircraft. The aircraft design and the performance analysis have been carried out by means of increasing fidelity methods, in order to obtain results as reliable as possible; the performances of the PrandtlPlane have been compared with those of a conventional reference aircraft. The purpose of the comparison is to assess the benefits achievable from the adoption of PrandtlPlane, specially in terms of reduction of fuel consumption per passenger and related environmental impact. The results proposed in this Thesis highlight the potential advantages of introducing PrandtlPlane aircraft on short-medium routes; in particular, given the same size constraints, the PrandtlPlane is able to transport 66% more passengers than the conventional competitor, with a related reduction in fuel consumption per passenger of more than 20%. The results obtained in this work can be of interest for following detailed developments of the PrandtlPlane configuration. The performance data obtained in this phase represent a well established basis for initializing research and development activities of higher fidelity, as experimental aerodynamic analyses. A PrandtlPlane radio-controlled scaled model has already been manufactured; a flight test campaign is currently ongoing, with the aim to verify the aeromechanical characteristics of the configuration, which are presently predicted through theory and simulations.