During countless hours of field experiments in a variety of different weather conditions, the Meteomatics Meteodrones have reliably collected valuable meteorological measurement data. The company, located in St. Gallen, has now carried out the worldwide first successful examinations on icing of Mini-UAVs and thereby taken a major step to the realization of flight operations in icing-favouring atmospheric conditions!

With the objective of getting deeper insights into these icing processes and consequently developing countermeasures or warning systems, Meteomatics, in cooperation with the Swiss Federal Office of Civil Aviation (FOCA), has launched the project SOPHIA (Study of Propeller Icing Hazard in Mini-UAV Aviation). According to the directives of the European Aviation Safety Agency (EASA), in the framework of this project, the icing of the rotor blades of the Meteodrones was examined for various different atmosphere alike conditions.

The measurements were conducted in the world's biggest Climate-Wind-Tunnel of Rail Tec Arsenal in Vienna, known for the precise simulations of atmospheric conditions leading to icing. Besides temperature and windspeed, the relevant parameters for icing are Liquid Water Content (LWC) and Mean Volume Diameter (MVD). The simulations included temperatures ranging between -2°C and -20°C in which both Stratus and Cumulus clouds with various particle diameters and liquid water contents could be realized. By measuring the rotary frequency, the power expenses and the thrust of the rotors, the influence of icing on the rotors of the Meteodrones was determined and in addition, the degree of icing of the Meteodrone sensors and parachute safety system captured optically.

For months, Meteomatics has developed a unique measurement system that withstands the rough Climate-Wind-Tunnel conditions and simultaneously allows reliable measurements. By combining optical and physical measurements, a classification of different icing degrees and characteristics were derived and thereby conclusions on the icing potential of different atmospheric conditions obtained. The photography of the rotor blade shows an impressive example of the icing effect which could complicate a controlled landing in the absence of countermeasures. The sensors as well as the parachute system however, could defy the icing and thus remained functional.

With the present findings, Meteomatics gained unknown insights into icing processes and reached a milestone in developing potential countermeasures which can help to realize drone flights in icing favouring atmospheric conditions. In future, further tests in conditions as freezing drizzle, rain and fog as well as snowfall will be carried out in order to complete the obtained findings.