The shock structure inside the inlet of an air-breathing hypersonic (or scramjet) engine is controlled largely by the inlet geometry. The ability to change that geometry in flight allows for the control of flow behavior and the enhancement of engine performance. Morphing structures based on cellular-core sandwich panels provide a useful platform for aerodynamic shape change without introducing seals or gaps into the structure. To test the concept of a variable geometry aerodynamic structure utilizing a cellular-core sandwich panel based design, a morphing supersonic nozzle was designed, built, and tested. The nozzle has the capability of changing its aerodynamic shape smoothly and continuously during operation, thus changing the Mach number in the test section of the nozzle.