Evaluation of the Potential of Photovoltaics for Extended Flight Times of Small eVTOL UAVs

This paper analyses the possibility of using photovoltaics as additional energy provider for small to medium-sized eVTOL UAVs. A simplified model for eVTOL UAVs, which covers all relevant areas of aircraft design, including aerodynamics, structural mechanics, propulsion and systems modelling, is presented. Sensitivity studies covering various design parameters, such as airfoil, wing geometry and propulsion system selection are performed to show their influence on the configurations' performance. The first result of this paper is, that a photovoltaic powered configuration can outperform a battery electric and it can be worth the effort to implement the solar cells. To achieve this, the aircraft needs to be as aerodynamic efficient as possible. Also higher efficiency solar cells increase the possible performance. Additionally there is a big influence of the time of year and the latitude onto the performance. Secondly a multi mission study is performed. This uses a more detailed model, as the preliminary study. It is to find the best solar eVTOL for a set of missions. A summary of this study's results is presented. Finally the best aircraft configuration, following this study, is presented. The main take aways are, that solar cells can have a positive effect on the overall performance of eVTOL UAVS. However some possible drawbacks are also identified, as the resulting aircraft require rather low speeds and a more complicated mission planning, because solar irradiance needs to be taken into account and monitored during the whole mission.