When visiting NASA Langley I had Josh Blake kindly take my picture by the Variable Density Wind Tunnel. Pioneered by Max Munk, leading theoretician in aerodynamics in America in our early years of aviation.
National historical landmark: The test section and airflow passages built into the VDT pressure vessel formed a continuous flow of pressurized air around the circuit and past the model. The direction of airflow is shown by the arrows. Both complete airplanes in model form and wing section models were tested.