Abstract: A mixed compression supersonic inlet system is provided which includes an external cowl, and an axisymmetric centerbody which preferably translates fore and aft. The centerbody of the inlet system is further provided with indexing segments which circumferentially rotate to provide longitudinal grooves or channels located on the outer periphery of the centerbody and which increase the effective flow area of the inlet. As the indexing segments rotate circumferentially, the channel width varies. The centerbody may also be provided with indexing segments formed of a first and second portion having hinged joints which slide forward and aft in a groove. One end of the indexing segment is hinged to the non-translating section of a translating centerbody. The indexing segments are positioned over a longitudinal channel. As the translating centerbody is translated forward, the hinges of the indexing segment slide in their respective grooves to expose the channel.