Flight research takes up where the other instruments of aeronautical research-wind tunnels, fluid dynamics, and mathematical analyses-leave off. No matter how the equations suggest it ought to fly, only by studying actual flight, often demanding complicated and dangerous maneuvers, can researchers discover the limits of flight and the true characteristics of experimental flight vehicles. The National Advisory Committee for Aeronautics (1915) and its successor, The National Aeronautic and Space Act (1958) were created to find out. Expanding the Envelope is the first book to explore the full panorama of flight research history, from the earliest attempts by such nineteenth century practitioners as England's Sir George Cayley, who tested his kites and gliders by subjecting them to experimental flight, to the cutting-edge aeronautical research conducted by the NACA and NASA. NASA historian Michael H. Gorn explores the vital human aspect of the history of flight research, including such well-known figures as James H. Doolittle, Chuck Yeager, and A. Scott Crossfield, as well as the less heralded engineers, pilots, and scientists who also had the "Right Stuff." While the individuals in the cockpit often receive the lion's share of the public's attention, Expanding the Envelope shows flight research to be a collaborative engineering activity, one in which the pilot participates as just one of many team members. Here is more than a century of flight research, from well before the creation of NACA to its rapid transformation under NASA. Gorn gives a behind the scenes look at the development of groundbreaking vehicles such as the X-1, the D-558, and the X-15, which demonstrated manned flight at speeds up to Mach 6.7 and as high as the edge of space.