Analysis of the mechanical transmission of the hybrid-electric propulsion system for an innovative regional transport aircraft

Today the emissions of CO2 and other pollutants have become a central theme for the development of solutions related to sustainable mobility. In this sense, in recent years, a lot of research has been conducted with the aim of promoting ever greater electrification of means of transport, in order to reduce the use of internal combustion engines, favoring the spread of hybrid or fully electric solutions. These innovations are noticeable in the field of the automotive industry; however, similar research is also being carried out in the aerospace field. This master's thesis arises from a collaboration between the Polytechnic of Turin and the Leonardo Labs, with the aim of studying the mechanical transmission system of a regional aircraft equipped with a hybrid propulsion system. The first chapter of the contribution analyzes the reasons that push toward the electrification of means of transport. Different types of architectures are then examined that could be used to design the gearbox in the studio. Finally, the calculation of the cruising operating point and the take-off operating point, necessary for the sizing of the gearbox, is carried out. The second chapter shows the chosen gearbox architecture and a first static dimensioning is performed. Subsequently, the third chapter illustrates the procedure for checking gearbox fatigue. After having explained how to define and verify the gearbox dimensions, the fourth chapter is dedicated to the optimization of the gearbox weight, according to some parameters that can be modified within appropriate ranges: a particular combination of these parameters allows to minimize the gearbox weight The fifth chapter of the article focuses on the dynamic analysis of the transmission: the equations used to model the gearbox, the propeller and the pitch controller are then illustrated. Once the dynamic model of the transmission was obtained, it was possible to observe the results to analyze the correct behavior of the model. Finally, the sixth chapter sets out the conclusions of the document and its possible future developments.