A Variable-Pitch Propeller System for Dual-Medium UAVs: Design, Modeling, and Validation

Amphibious UAVs are attracting significant interest due to their potential applications in search and rescue, environmental monitoring, and military reconnaissance. However, designing a propulsion system that performs efficiently in both air and water remains a formidable challenge, given the divergent aerodynamic and hydrodynamic requirements. This paper investigates the feasibility of employing a variable-pitch propeller system in a quadcopter designed for amphibious operations. The study focuses on evaluating the system's performance across both media, with particular attention to the challenges inherent in a shared propeller design and its modeling. Experimental results indicate that while a higher collective pitch mode delivers sufficient thrust for aerial flight, the blade geometry optimized for air results in excessive drag during underwater operation. These findings highlight critical trade-offs between aerodynamic and hydrodynamic performance and underscore the need for further research into blade shape optimization, fluid-structure interactions, and advanced rotor designs. Our proposed tilting pitch rotor approach offers a promising avenue toward the development of efficient multi-medium propulsion systems for future amphibious UAVs.