RAMS estimation of hybrid-electric aircraft propulsion architectures

It is a truth universally acknowledged that we are living in a very important period in the area of climate change. The effects of greenhouse gas emissions and pollutants are manifesting themselves with greater frequency and intensity than ever before, and as a result, the world is moving in a more environmentally sustainable direction. This implies that the aviation sector is also studying solutions to reduce greenhouse gases. The aim of this thesis is to show the reader the reliability aspect of new turbo-electric and turbo-hybrid architectures, as well as the current state of the art of such technologies that various companies and universities are studying and developing. In order to do this, designs were analysed that were both at an advanced stage of study and of relative importance in terms of possible application. The analysis was carried out by creating Reliability Block Diagrams of these architectures (based on available information), where each block represents a component/sub-system with its relative reliability value, which in turn was derived from their failure rates. Once the failure rate of the system under consideration has been derived, it is compared with the values of current commercial aircraft. In general, the comparison shows that many of these architectures are not yet mature and the failure rates differ from current aircraft by as much as 6/7 orders of magnitude. This is due to the fact that the architectures are generally more complex and also because they use technologies that are either in the development phase or, if they exist, have not yet realised the aeronautical version. The only exception is the STARC-ABL programme, which carries a more conservative architecture and is realised with all existing technologies.