Aerodynamic assessment of icing effects on swept wings is an important component of a larger effort to improve three-dimensional icing simulation capabilities. An understanding of ice-shape geometric fidelity and Reynolds and Mach number effects on the iced-wing aerodynamics is needed to guide the development and validation of ice-accretion simulation tools. To this end, wind-tunnel testing was carried out for a 13.3%-scale semispan wing based upon the Common Research Model airplane configuration. The wind-tunnel testing was conducted at the ONERA F1 pressurized wind tunnel with Reynolds numbers of 1.6×10 6 to 11.9×10 6 and Mach numbers of 0.09 to 0.34. Five different configurations were investigated using fully 3D, high-fidelity artificial ice shapes that maintain nearly all of the 3D ice accretion features documented in prior icing-wind tunnel tests. These large, leadingedge ice shapes were nominally based upon airplane holding in icing conditions scenarios. For three of these configurations, lower-fidelity simulations were also built and tested. The results presented in this paper show that while Reynolds and Mach number effects are important for quantifying the clean-wing performance, there is very little to no effect for an iced-wing with 3D, high-fidelity artificial ice shapes or 3D smooth ice shapes with grit roughness. These conclusions are consistent with the large volume of past research on icedairfoils. However, some differences were also noted for the associated stalling angle of the iced swept wing and for various lower-fidelity versions of the leading-edge ice accretion. More research is planned to further investigate the key features of ice accretion geometry that must be simulated in lower-fidelity versions in order to capture the essential aerodynamics. Determine the level of ice-shape geometric fidelity required for accurate aerodynamic simulation of sweptwing icing effects. This paper, along with a series of companion papers, 5-7 provides initial results for these remaining objectives. Additional wind-tunnel testing and future publications are planned. The approach used to accomplish these objectives has been successfully carried out in previous icing aerodynamics studies of straight wings and airfoils.In past work, geometric representations of ice accretion have been attached to wings and models and tested in dry-air wind tunnels or in flight. These geometric representations are known as "artificial ice shapes" or "iceaccretion simulations." The various methods and geometric fidelities associated with developing artificial ice shapes have been investigated in a previous NASA-ONERA collaborative research effort called "SUNSET1." 8 Since that time, a new approach for producing high-fidelity artificial ice shapes have been developed using 3-D scanning and rapid-prototype manufacturing (RPM). 9 In past studies of icing performance effects on airfoils, systematic investigations of Reynolds and Mach number effects were conducted. [10][11][12][13][14][15][16] Over the course of many years, it was fo...