An experimental investigation of highly underexpanded exhaust jets impinging in a direction normal to a curved surface was conducted in the NASA-Langley Research Center 55-foot vacuum cylinder. The investigation included measurements of impingement pressures and measurements of various normal shock characteristics. Variables of the investigation were the size of the jet, jet-exit Mach number, exhaust gas, distance of the jet from the impingement surface, curvature of the surface, and jet-exit to ambient pressure ratio. The experimental data are presented and compared with available theory. / Master of Science