Test flying became important during World War I, at the Royal Aircraft Establishment (RAE) in the United Kingdom. During the 1920s, more test flying was done by the RAE in the United Kingdom, and by the National Advisory Committee for Aeronautics (NACA) in the United States. In the 1950s, NACA changed into the National Aeronautics and Space Administration (NASA). Test flying became more scientific during these years.