Experimental Investigation on the Effects of Icing on Multicopter UAS Operation

View Video Presentation: https://doi.org/10.2514/6.2021-2676.vid The implications of icing for the operation of multicopter unmanned aerial systems (UAS) have not been thoroughly investigated yet. Due to the geometry and flight envelope of multicopters, existing knowledge in the field of aircraft icing can only be applied in a limited manner. More research is required to better understand the influence of icing on the flight characteristics, on-board systems, and sensors of multicopters. Studies performed on single UAS propellers show that icing can lead to critical flight conditions in a very short period of less than 60 seconds. Icing of the propeller blades reduces the aerodynamic performance while increasing the required power input at constant rotational speed. This paper features a more top-level approach and investigates the effects of icing on the operation of a multicopter with 25 kg maximum take-off weight. Therefore, experimental icing tests were conducted at the Rail Tec Arsenal Climatic Wind Tunnel in Vienna, Austria. The multicopter was mounted on a testbed and operated in defined icing conditions according to Appendix C and Appendix O (freezing drizzle) conditions. The rotational speed of the propellers was maintained until a certain power limit, or the predefined icing time was reached. The final ice accretion was documented by means of 3D scanning and evaluated. Moreover, a surface roughness analysis of the propeller blade ice accretion was performed.