The diffuser section of the 16-foot supersonic wind tunnel at Tennessee’s Arnold Air Force Base. Whatever you do, don’t stand there when they turn it up to Mach 4. Photo by Lance Cheung.

There are three wind tunnels in this PWT facility. They use two closed-circuit wind tunnels (one to simulate transonic speeds and the other supersonic), with 16-foot-square test sections, are also used for conventional aerodynamic tests. Air that has been pushed through the section seen has passed through progressively narrowing tunnel sections and 90-degree turns that lead to the test section.

The facility is devoted to aerodynamic and propulsion integration testing of large-scale aircraft models. Some of the most powerful electric motors ever built are located in the PWT facility.