The mid- 1940s were undoubtedly some of the happiest and most fruitful years of Tsien's life. He was in his early thirties and at the very height of his creative powers. After four years of working as a research assistant, Tsien was asked to stay on as an assistant professor of aeronautics at Caltech, a post he accepted in the fall of 1943. Even though Tsien had made an agreement with the Chinese government to stay just one more year in the United States, China was dependent on U.S. efforts to defeat Japan and did not press the issue. At Caltech, Tsien would divide his time between teaching and research in aerodynamics and jet propulsion. And, just as Theodore von Kármán had done as a young professor in Aachen, Tsien would learn to move smoothly during the war years among the triple spheres of academia, industry, and government.
During the 1940s, Pasadena was undergoing growth so phenomenal that merchants referred to that ten-year period as "the Miracle Decade." These were the boom years of the aircraft industry for Los Angeles, when more than 100,000 airplanes would be manufactured for the U.S. government.The statistics were simply astounding. In 1939 there were 13,300 aircraft workers in