A Study on Configuration of Propellers for Multirotor-like Hybrid Aerial-Aquatic Vehicles

This paper presents a study on the configuration of propulsion systems for multirotor-like hybrid vehicles that travel in both, aerial and aquatic medium, hereafter called Hybrid Unmanned Aerial Underwater Vehicles (HUAUVs). Following, we evaluate the impact of diameter and shape of propellers, and the medium in which the robot moves, on thrust generation and energy consumption. Sets of counter-rotating propellers (CRPs) and single propellers propulsion systems were experimentally evaluated in air and under the water. One of our conclusions is that aerial counter-rotating propellers, used in the state-of-the-art hybrid vehicles, are relatively inefficient in the air, and even more in the water, and this energy loss must be taken into account during the platform project. Furthermore, we also demonstrate that aquatic screwlike propellers are more efficient in the water than aerial ones, equally contradicting the current literature. Moreover, since aquatic propellers provide more thrust with smaller diameters, they improve our capacity to miniaturize hybrid vehicles.