Passive Ice Protection Systems for Unmanned Aerial Vehicles Applications: A Review.

Unmanned aerial vehicles (UAVs) are promising platforms for operations in alpine regions due to their compact size, advanced camera systems, and ability to take off and land in confined areas. In such conditions, one of the most significant challenges for UAVs is operating in icing environments, as ice accretion can compromise the aerodynamics of the propellers and can potentially lead fto a loss of control and vehicle failure. To date, active de-icing solutions, such as electrothermal systems, have been employed in the aeronautical sector; however, these systems are energy-intensive. This review addresses passive ice protection systems from a material science prospective, by focusing on coatings which mitigate ice formation without energy consumption. A comprehensive description of the strategies to design an icephobic surface is presented and the state-of-the-art icephobic coatings are analyzed, such as superhydrophobic surfaces, elastomers, liquid infused surfaces, gels, polyelectrolytes, sol gel coatings, metal-organic frameworks. A key focus is devoted to the characterizations for assessing ice mitigation of such coatings, i.e., contact angle and hysteresis measurements, and to the correlation between durability and number of icing and de-icing cycles. The most relevant solutions for aerial vehicles are described in the final part of this review.