A computer-based, proportional-integral control system for supersonic blowdown wind tunnels was developed in a LabVIEW environment. The control algorithm is based on numerically integrating the differential equations used to model a supersonic blowdown wind tunnel in which the proportional and integral control terms were added and tuned in a simulation to determine their appropriate values. Values for these control terms can be obtained using a spreadsheet allowing for variation of the test section Mach number, test section area, stagnation pressure and plenum chamber volume as well as the pressure, temperature and volume of the storage tank. Accounting for the variation of many terms allows the control terms and resulting LabVIEW program to be easily integrated across different facilities. Experimental verification is provided along with a discussion of control valve calibration, optimization of control constants and additional capabilities of LabVIEW.