Abstract: This invention relates to a new land based gas turbine in simple or combined cycle configuration, which permits a user to incorporate air or steam cooling of hot gas turbine parts with minimal change in components, and which also incorporates design changes enabling certain turbine components to be used without change in both 50 and 60 Hz turbines. The invention here specifically relates to parameter selection for the operating cycles of 50 and 60 Hz gas turbines with air or steam cooling, and in simple or combined cycle configuration. A method of operating a combined cycle, gas turbine broadly comprises the steps of compressing inlet air with a multi-stage compressor with a pressure ratio of about 23 to 1; directing substantially all of the air discharged from the compressor to a combustion system to produce gaseous products of combustion; directing the gaseous products of combustion through the turbine; and exhausting the gaseous products of combustion.