A hybrid propulsion system for a high-endurance UAV: configuration selection, aerodynamic study, and gas turbine bench tests

In recent years, renewed interest in the development of unmanned aerial vehicles (UAVs) has led to a wide range of interesting applications in reconnaissance and surveillance. In these missions, the noise produced by propeller-driven UAVs is a major drawback, which can be partially solved by installing an electric motor to drive the propeller. While the evolution of high performance brushless motors makes electric propulsion particularly appealing, at least for small and medium UAVs, all electric propulsion systems developed to date are penalized by the limited range and endurance that can be provided by a reasonably sized battery pack. In this paper we propose a hybrid propulsion system based on a recently developed ultramicro gas–turbine (UMGT), which can be used to power an electric generator, providing a significant range and (or) mission time extension. The UMGT is undergoing operational testing in our laboratory, to identify the most suitable configuration and to improve performance: a new compact regenerative combustion chamber was developed and several tests are being carried out to reduce its weight and size so as to increase, all other things being equal, the vehicle payload. This paper aims to propose a high endurance UAV, by a preliminary configuration selection and aerodynamic study of its performance