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Digital archive of theses discussed at the University of Pisa


Thesis etd-11092022-150110

Thesis type
Tesi di dottorato di ricerca
Thesis title
Development of methodologies for the design and performance assessment of box-wing hybrid-electric aircraft for urban and regional transport applications
Academic discipline
Course of study
tutor Dott. Cipolla, Vittorio
relatore Prof. Di Rito, Gianpietro
  • Box-wing
  • Conceptual design
  • Hybrid-electric
  • Optimization
  • Tilt-Wing
  • Urban Air Mobility
Graduation session start date
The impact of aviation on climate is a concerning issue. The forecast for the aviation market shows that the number of passengers will double in the next 20 years, and the noxious emission in the aviation sector will dramatically increase. To reduce the impact of aviation, disruptive solutions are currently investigated; two research fronts can be identified: one related to the airframe; the second related to the powertrain. Disruptive solutions on the aircraft airframe (e.g. box-wing and blended wing body) are compulsory since tube-and-wing lift-to-drag ratio has reached its maximum potential; therefore, only radical change can allow to meet a step forward. Adoption of alternative sources of energy (e.g. drop-in fuel or battery) represents a disruptive solution to the powertrain which has the potential to reduce aircraft emissions by far. Nevertheless, the adoption of innovative solutions in the powertrain, such as battery, could be a hurdle because of their current low specific energy. To overcome this issue, coupling airframe disruptive solutions with innovative powertrain side could mitigate the electric propulsion drawbacks and reduce the impact of the aviation sector on climate change.
Together with climate change, a second relevant issue to be tackled is the enhancement of the quality of life of people in highly populated urban scenarios. Urban congestion will dramatically increase in the next years since the number of megacities is expected to raise. The introduction of urban air-taxi could be a compelling solution to mitigate the problem and enhance the quality of life of people.

This dissertation focuses on the development of conceptual design methodology for hybrid-electric and full-electric aircraft with box-wing airframe in regional and urban scenarios, respectively. Box-wing architecture is a viable solution in the electrification context thanks to its unique capabilities: minimization of the induced drag which enhances the lift-to-drag ratio, and the high lifting capability.
This thesis is divided into three parts. The first part describes the tools and methodology developed; specifically, the main changes with respect to aircraft design procedures for aircraft with thermal powertrain are highlighted.
The second part focuses on the application of the conceptual design methodology of hybrid-electric aircraft in the regional scenario. First, the design procedure has been used to identify the main correlation between the design variables and the selected figure of merit; then, an ad-hoc optimization tool has been developed to maximize aircraft performance considering block fuel consumption as figure of merit. Accordingly, a comparison between box-wing and tube-and-wing aircraft has been carried out to highlight pros and cons of each configuration. The results have shown that box-wing hybrid-electric aircraft can reduce fuel consumption up to 74% with respect to tube-and-wing hybrid-electric aircraft, and up to 88% with respect to a thermal tube-and-wing aircraft.
The third part focuses on the application of the conceptual design methodology of full-electric aircraft in the urban scenario. This section introduces an innovative solution based on box-wing configuration and aims to find the main potentiality and bottlenecks in this unexplored scenario.