If an Unmanned Aerial Systems (UAS) encounters icing conditions during flight, those conditions might result in degraded aerodynamic performance of the overall UAS. If the UAS is not reacting appropriately, safety critical situations can quickly arise. Thereby, the rotors, respectively the propellers of the UAS are especially susceptible due to the increased airflow through their domain and the corresponding higher impingement rate of supercooled water droplets. In many cases, the UAS cannot be properly operated if the rotors are not fully functional, as they are a vital component. The FFG/BMK funded research and development project
“All-weather Drone” is investigating the icing phenomenon on UAS rotors for a 25 kg maximum take-off weight (MTOW) multirotor UAS and evaluating the feasibility of possible technical ice detection and anti-/de-icing solutions. This paper presents results from the investigation carried out at the Rail Tec Arsenal (RTA) icing wind tunnel (IWT) in Vienna, Austria, where UAS rotors were exposed to defined icing conditions based on EASA CS-25 Appendix C. The experimental tests featured various rotors which were exposed to icing conditions without any protective measures to better understand the influence of ice accretion on the aerodynamic performance. In addition, possible technical solutions in form of an electrothermal and chemical anti-/de-icing system, as well as an ice-repellent surface coating were investigated. During the tests, the performance (power, thrust, torque) of the UAS rotors was monitored. The final ice accretion was documented by 3D laser scanning and photographs. The objective of this work is to contribute to a better understanding of icing of UAS rotors, while also investigating solutions that might enable the safe operation of multirotor UAS in icing conditions in the future.