Initial Sizing of Hybrid Electric VTOL Aircraft for Intercity Urban Air Mobility
Ugur Cakin, Zafer Kaçan, Zeynel Abidin Aydogan, Ipek Kuvvetli
Abstract
As the urban air mobility market has been growing, the emission of carbon dioxide caused by the conventional propulsion systems has been increased gradually and electrification in developing aviation technology has come into prominence. However, there is a drawback in the electric aviation development since the battery power and energy densities are not sufficient for all mission concepts of urban air mobility. Therefore, the hybrid electric configurations are outstanding concepts to reach future concepts of air mobility. In this paper, two hybrid electric concepts of urban air mobility, which are lift-cruise and multicopter, are designed conceptually for intercity mission (city-to-near city) with different range and hybrid power allocation settings. Top level requirements including mission profile, VTOL aircraft configuration and hybrid electric propulsion are defined according to technology assessment of Uber Elevate and Transformative Vertical Flight studies. Initial sizing of both configurations is performed with multidisciplinary optimization approach which includes component sizing, mission performance analysis and weight estimation. As a result of study, maximum takeoff weight, internal combustion engine weight and battery weight increase dramatically for both configurations as range and hybridization factor increase. It is seemed that more battery power dependent configurations are not feasible for intercity mission considering todays battery technology. For hybrid electric VTOL aircrafts, more ICE power dependent configurations should be preferred in intracity missions.