An symmetric "penshape" exit was designed by the method of characteristics for a nozzle pressure of 15. This configuration was experimentally evaluated in quiescent-air tests over a range of pressure ratios from 4 to 16. In an attempt to achieve throat-area modulation, a scheme was also investigated wherein a teardrop-shape ramp moved out of the concave expansion surface to restrict the flow.

An axisymmetric variable-geometry cascade inlet has been proposed and demonstrated. By means of a translating spike, an annular double-passage cascade arrangement was formed at a Mach number of 1.9 and a single-passage configuration with an internal area discontinuity (vortex trap) was effected at a Mach number of 3.05.