Prospective alternative propulsion systems for unmanned aerial vehicles

The paper presents selected issues concerning alternative power sources and propulsion systems meant for unmanned aerial vehicles (UAVs). The implementation of new propulsions in aviation is a laborious and long-term process, mostly due to safety and economical restrictions and requirements. Broadly, exploited solutions known from automotive industry may serve as a basis for development in aerospace technology, but cannot be applied without considering specific technical aspects (related to aircraft technology and flying objects physics). These aspects are mentioned in the text and some issues concerning suitability of types of aircraft are described. The paper presented contains a review of research on non-conventional propulsion systems for UAVs, conducted in Rzeszow University of Technology. Selected results of the research the fuel cell and the solar-cell UAVs and the aerial hybrid-electric drive test stand are shown in adequate pictures. The small-unmanned flying objects seem to be an accurate basis for such research. They allow reducing costs and improving safety in comparison to full-scale manned aircraft. They are also much quicker in manufacturing and easier to maintain and repair. Moreover, due to their various applications they may comprise the target market for this kind of propulsions. In particular, the issues of parallel hybrid-electric propulsions, fuel cell and solar-cell-assisted systems with appropriate examples are mentioned in the paper..