Photo courtesy of NASA

Variable Density Tunnel: arriving by rail on February 3, 1922 from the Newport News Shipbuilding and Dry Dock Company, and exterior of tunnel in 1929

The Variable Density Tunnel was deemed obsolete by the standards of the day in the 1940s and was gutted. It was then used as a pressure tank to support the operation of the Vertical Wind Tunnel and Low Turbulence Wind Tunnel. Although declared potentially unsafe for further operations in 1978, all modern Variable Density Tunnels are merely an extension of this idea first formulated and put into operation by Munk in 1921. The Variable Density Tunnel was a technological jump that rejuvenated American aerodynamic research which had fallen behind European countries prior to World War I and eventually led to the development of the best aircraft in the world. Source

Good one! That would be a Coanda Effect "flying saucer", but the Avro Aerocar wasn't built until the fifties, though disk designs would certainly be something to test in a wind tunnel But this thing was built by a German Scientist in 1921ish. Even Tesla didn't have his saucer patent yet. The National Monument page states...

So less than 20 years after flight was first achieved, we have the precursor to NASA (the NACA) having German scientist building experimental wind tunnels that were a "a technological jump"

I find that curious 

NACA Technical Note 364.pdf

The four principal HL-10 pilots are seen here with the lifting body aircraft. They are, left to right; Air Force Major Jerauld R. Gentry, Air Force test pilot Peter Hoag, and NASA pilots John A. Manke and Bill Dana. The HL-10 was one of five lifting body designs flown at NASA's Dryden Flight Research Center, Edwards, California, from July 1966 to November 1975 to study and validate the concept of safely maneuvering and landing a low lift-over-drag vehicle designed for reentry from space.

NASA Center:   Dryden Flight Research Center
Image # :  EC64-404
Date :  01/01/1964M2-F1 In Tow Flight
Full Description

The M2-F1 lifting body is seen here under tow at the Flight Research Center (later redesignated the Dryden Flight Research Center), Edwards, California. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a "flying bathtub," and was designated the M2-F1, the "M" referring to "manned" and "F" referring to "flight" version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. These initial tests produced enough flight data about the M2-F1 to proceed with flights behind a NASA C-47 tow plane at greater altitudes. The C-47 took the craft to an altitude of 12,000 feet where free flights back to Rogers Dry Lake began.

NASA Center:   Dryden Flight Research Center