A method for minimizing sulfidation corrosion by indirectly heating the air for the high-temperature portion of a gas-turbine cycle is proposed and discussed. The exhaust air from the high pressure turbine passes through the combustion chamber and air heater and then through the low-pressure turbine. Calculations of thermal efficiency and weight are made for both simple and regenerated versions of this cycle. For comparison, similar weight and efficiency calculations are made for conventional simple and regenerated cycles. These calculations show that, in comparison with the conventional simple cycle marinized aircraft engine, weight of the proposed engine is about 100 percent greater thermal efficiency is about the same but on the favorable side, air flow per horsepower is less by about 40 percent. In comparison with a conventional regenerated engine, the thermal efficiency of a regenerated indirect air cycle engine is about the same, but the weight is about 50 percent less and the air flow is reduced by about 40 percent. With the proposed cycle, high compression-ratio engines are shown to provide high efficiency in the regenerated version, in contrast to conventional regenerated engines where low compression ratios must be used.