Advances in the 1930s
Work on a much bigger, 24 ft diameter, wind tunnel began in 1932 to allow full scale testing of aircraft. The tunnel was to be housed in a steel and re-inforced concrete building some 230 ft in length, 140 ft wide and 50 ft high (Q121 Building). Electric motors of 2000 hp produced a maximum airspeed of 115 mph. The tunnel was officially opened on April 4th 1935 and the first aircraft to be tested was a Gloster Gauntlet fitted with a Bristol Mercury engine.
Also in 1935 plans were approved for a new atmospheric general purpose tunnel to replace the No2 7 ft tunnel. This new tunnel came into operation in 1938, with a test section of 11 ½ x 8 ½ ft and a maximum speed of 220 ft/sec.
High Speed Tunnel
By the late 1930s the increasing speeds of aircraft had shown the need for a high-speed tunnel and a new tunnel was built capable of a maximum wind-speed of 600 mph in pressures varying from 1/6 to four times atmospheric pressure. A standard temperature of 15 deg C was maintained in the working section by means of a large cooling plant. This tunnel was officially opened in 1942.