Recent aircraft accidents and incidents in Super-cooled, Large Droplet (SLD) conditions has led to the development of a technology roadmap designed to improve the capabilities of SLD engineering tools. Research is required to evaluate and enhance the capabilities of icing test facilities and analytical codes for SLD applications. In support of this effort, the objectives of this study were to identify and document key features of SLD ice accretions on unprotected surfaces and determine their aerodynamic effects. Icing experiments were carried out on a full-scale wing section from a commuter class aircraft. Three key features were determined from the resulting ice accretions: horns, nodules and clear ice. All of the documented ice accretions contained either two or three of these features. Follow-on aerodynamic testing was carried out on a sub-scale model having the same airfoil as the icing model. The ice features were scaled in size by the ratio of the model chord lengths and were simulated with simple geometric materials. Aerodynamic performance measurements were performed at Re = 1.8×10⁶ and Ma = 0.18 with various combinations of the ice feature simulations applied to the model. The largest performance degradations occurred for SLD accretions having horn features. The relative size of the clear ice region upstream of the horn played an important role in the resulting penalties, while the nodule features downstream of the horn did not. SLD accretion simulations without horns had less of an aerodynamic penalty. The nodule size, spacing and chordwise extent and clear ice thickness and chordwise extent were important factors in the resulting performance.