T study of turbulent boundary layers with surface mass addition has been of interest for many years. The injection of gases into the boundary layer (either by ablation or transpiration) reduces the skin friction and heat transfer to the surface. All of the previously published heat-transfer and skin-friction measurements have been made over ranges of Mach number and mass injection rate that are within the limits of conventional boundary-layer theory. Several experimenters have presented data for turbulent heat-transfer reduction with air injection for Mach numbers up to 4.35. These measurements were obtained for dimensionless injection rate parameters less than 3.5. Other experimenters have presented air injection data on turbulent skin friction for Mach numbers up to 4.3 and dimensionless injection rate parameters up to 4.5. Accumulation of these data has revealed a more significant dependency of skin-friction reduc-