A Comprehensive Review of Propeller Design and Propulsion Systems for High-Altitude Pseudo-Satellites

In both scientific and industrial fields, there has been a notable increase in attention toward High-Altitude Pseudo-Satellites (HAPS) in recent years. This surge is driven by their distinct advantages over traditional satellites and Remotely Piloted Aircraft Systems (RPAS). These benefits are particularly evident in critical areas such as intelligent transportation systems, surveillance, remote sensing, traffic and environmental monitoring, emergency communications, disaster relief efforts, and the facilitation of large-scale temporary events. This review provides an overview of key aspects related to the propellers and propulsion systems of HAPS. Firstly, an analysis of the propulsion systems proposed in literature or employed by HAPS is presented, focusing on both the technical challenges and advancements in this emerging field. Given that propellers remain the most efficient propulsor for such applications, the discussion then shifts to the fundamental principles of propeller theory, followed by an overview of innovative design methodologies proposed in literature for propellers intended for high-altitude operations and a discussion concerning methodologies for evaluating their performance. The unique atmospheric conditions at high altitudes result in distinct characteristics for the propellers of stratospheric airships compared to conventional ones.