Ice Accretion on Small Unmanned Aircraft

Abstract

Aircraft icing is an important and complex problem. Small unmanned aerial systems are becoming increasingly common in high quality operations. The hazards of icing on these smaller aircraft are significant and primarily unexplored. The need for greater understanding of accretion physics at low speeds and low altitudes is obvious when considering the ways in which icing models for manned aircraft are unsuited for small UAS. Cylinder models are incredibly useful in that the stagnation region has the highest amount of geometry change due to ice and has the highest rate of heat transfer. Current numerical tools are not verified under low velocities. The icing model developed is be suited for UAS using analytic methods suited for low velocities and empirically derived heat flux relations. Experimental heat transfer tests were done to support accretion model. Flight testing was used to gather atmospheric data in low altitude icing conditions, gain qualitative data on ice accretion, and to investigate heat flux at the low velocity range.