The idea of long-life turbomachinery that requires no oil or servicing is immediately attractive. The concept of air-lubricated bearings provides the basis for such a design. This paper describes the advantages and problems in the application of air bearings to closed-and open-cycle machinery. It discusses the design and performance characteristics of several prototype air bearing machines. The results of extensive ground tests and thousands of hours of field experience prove that practical air bearing turbomachines for open-cycle applications are a reality.