Newly formed Langley Memorial Aeronautical Laboratory (LMAL) began operations in 1917 with almost no experience in wind tunnel design and operation. There was no cadre of experienced researchers nor a broad background of wind tunnel experience; NACA engineers were reduced to copying European technology. With relatively minor changes, the first Langley wind tunnel was patterned after one located at the British National Physical Laboratory. The first wind tunnel of NACA was therefore obsolete when it was built.
In fact, so inexperienced were the NACA personnel that they chose to build first a one-fifth-scale model of the English tunnel rather than an actual operating tunnel. The primary purpose of the so-called Model Tunnel was to get some fast first-hand operating experience and, hopefully, improve the NPL tunnel design.
Bolstered by experience with the model, they next built NACA Wind Tunnel No. 1-a low-speed tunnel with no return circuit for the air passing through the test section. A 200-horsepower electric motor generated airspeeds of 90 mph in the 5-foot-diameter circular test section. (The British National Physical Laboratory already had a tunnel with an area five times larger.)
Nevertheless, it was a beginning. Operation began on June 11, 1920. Honeycomb sections and screens ensured good airflow quality around the models, and the electric motor provided precise control of airspeed. The supersensitive NPL balance was adopted for measuring forces and torques. Scale models of the famous Curtiss Jenny-operating in the wake of a rotating propeller-were tested to evaluate propeller slipstream effects. But the data obtained from this and other tests were not realistic enough to be useful in aircraft design. Wind tunnel No. 1 was really a learning tool-something to get the United States back into...
....aeronautical research. From the standpoint of research results, tunnel No. 1 was relatively unproductive, but it must also be recorded that within 3 years a new tunnel had been built-one that leapfrogged all the tunnels then in operation in Europe. The new tunnel was called the Variable Density Tunnel (VDT).