Experimental studies supported by detailed numerical computations are being conducted to examine the effects of nonequilibrium air chemistry on the characteristics of shockhundary layer and shock/shock interaction regions over a series of spherically blunted double cone configurations and a hollow cylinder-flare model. Comparisons between the results from the experimental studies and the numerical predictions are being used to evaluate, select, and improve the models of chemistry employed in the codes for predicting vehicle performance in the Mach 6 to 15 high altitude flight regime. Flowfield and surface measurements will be made to characterize the flow through the contoured nozzles, and these measurements will be compared with numerical computations from the reservoir to the exit plane of the nozzle. Detailed measurements of the heat transfer and pressure distributions over the models, as well Schlieren and holographic interferometry images of the flowfield are being made for a range of freestream conditions. Measurements will be made in air and nitrogen flows for a range of velocities between 6,000 to 15,000 ft/sec (1.8 and 4.6 km/s) and a range of Reynolds numbers to obtain conditions for which there are laminar and transitional rexting flows in the contoured nozzle and over the models. The experimental and theoretical studies were closely coupled to provide direct guidance during the course of the experimental program. Initial simulations of the LENS I facility flow at its highest enthalpy operating condition show that there is a significant level of chemical reaction in the test-section. Lower reservoir pressures result in higher levels of chemical reaction in the test section, as expected. Simulations of double cone flllows show some dependence on the chemical state of the gas, but because of the highly reacted free-stream this dependence is relatively weak.