This application calculates the compressor power for a fixed geometry supersonic wind tunnel. The test section operates at Mach 2.5, simulates an altitude of 21 km, and has a circular cross section with a diameter of 25 cm. A supersonic fixed-area diffuser follows the test section. A cooler between the compressor and the nozzle ensures that the air at the compressor inlet and in the test section have the same stagnation temperature. The air entering the compressor and in the test section has the same stagnation temperature. The compressor is isentropic, and friction and boundary layer effects are not considered.