Construction of this facility began in 1950-1951 and continued until 1955. Because no one wind tunnel could meet all the demands for additional research facilities simulating the entire range of aircraft and missile flight, NACA chose to build the Ames tunnel with three separate test sections drawing power from a common centralized power plant. The transonic test section spanned 11 by 11 feet (3.3 x 3.3 m), while the two supersonic sections were smaller: nine by seven feet (2.7 x 2.1 m) and eight by seven feet (2.4 x 2.1 m). Giant valves 20 feet (6 m) in diameter supplied air from one supersonic leg to another.