National Transonic Facility

The National Transonic Facility (NTF), also known internally as facility 1236, is a high-pressure, cryogenic, closed-circuit wind tunnel at the Langley Research Center in Hampton, Virginia. It uses nitrogen gas, at high pressure, to cool the air which allows flight aerodynamics to be duplicated in small scale.

Source: Wikipedia — National Transonic Facility (CC BY-SA 4.0)