Identification of an Electric UAV Propulsion System in Icing Conditions

In-flight atmospheric icing is a severe hazard for propeller-driven unmanned aerial vehicles (UAVs) that can lead to issues ranging from reduced flight performance to unacceptable loss of lift and control. To address this challenge, a physics-based first principles model of an electric UAV propulsion system is developed and identified in varying icing conditions. Specifically, a brushless direct current motor (BLDC) based propeller system, typical for UAVs with a wing span of 1-3 meters, is tested in an icing wind tunnel with three accreted ice shapes of increasing size. The results are analyzed to identify the dynamics of the electrical, mechanical, and aerodynamic subsystems of the propulsion system. Moreover, the parameters of the identified models are presented, making it possible to analyze their sensitivity to ice accretion on the propeller blades. The experiment data analysis shows that the propeller power efficiency is highly sensitive to icing, with a 40% reduction in thrust and a 16% increase in torque observed on average across the tested motor speeds and airspeeds. The resulting reduction in propeller efficiency can be as high as 70% in the worst-case scenario. These findings provide valuable insights into the impact of ice accretion on electric propeller systems and contribute to the development of effective ice protection systems for safer UAV operation in cold environments.