A simulation of the pressure and temperature responses of the 20 inch Supersonic Wind Tunnel (SWT) is developed. The simulation models the tunnel system as a set of lumped parameter volumes connected by flow regulating elements such as valves and nozzles. Simulated transient responses of temperature and pressure for the five boundary points of the 20 inch SWT operating map are produced from their respective initial conditions, tunnel operating conditions, heater input power, and valve positions. Upon reaching steady state, a linearized model for each operating point is determined. Both simulated and actual tunnel responses are presented for comparison. Motter, Mark A. Langley Research Center...