UAV Icing: A Unified Icing Severity Index Derived from Performance Degradation

Abstract

A problem that unmanned aerial vehicles (UAV) operators face when dealing with in-flight icing conditions is a reliable way to assess icing severity risk. This paper aims to develop an icing severity index that looks at the combined effect of icing performance degradation on wings and propellers for a specific UAV. The index developed in this paper will provide UAV operators with an easier way to assess icing risk. Icing severity indices for the wings and propeller are computed separately to highlight the individual contributions of power increase. Combining them yields the unified icing severity index. To develop the unified icing severity index, a focus is put on the power consumption increase resulting from aerodynamics performance degradation that is due to ice. The wings and propeller will be subject to different icing conditions specified by median volume diameter (MVD), and temperature. Two propeller rotation rates are also tested for each of these icing conditions. The tests are performed through computer simulations using a pre-existing simulation framework. Each condition will yield the power consumption from these simulations, where the UAV will fly the same straight path. These parameters are compared against the baseline, clean condition, to yield an index. Results from a case-study show significant differences in power consumption between different icing conditions. The ice affects performance degradation on the wing and propeller differently depending on ice type. The propeller degradation is the least severe for glaze ice and the worst for the rime ice case. The wing degradation is the least severe for rime ice case and worst for the glaze ice case. Combining the wing and propeller degradation show 8 times increase in power consumption for rime ice compared to clean condition in the worst case.