less Aircraft Research Division at Langley, until the early fifties headed by Robert R. Gilruth, conducted the NACA program of aerodynamic research with rocket-launched models.27
The most celebrated part of the postwar aeronautical research effort in the United States, however, was the NACA-military work with rocket-propelled aircraft. In 1943, Langley aerodynamicist John Stack and Robert J. Woods of the Bell Aircraft Corporation, realizing that propeller-driven aircraft had about reached their performance limits, suggested the development of a special airplane for research in the problems of transonic and supersonic flight. The next year, the Army Air Forces, the Navy, and NACA inaugurated a program for the construction and operation of such an airplane, to be propelled by a liquid-fueled rocket engine. Built by Bell and eventually known as the X–1, the plane was powered by a 6000-pound-thrust rocket burning liquid oxygen and a mixture of alcohol and distilled water. On October 14, 1947, above Edwards Air Force Base in southern California, the X—1 dropped from the underside of its B–29 carrier plane at 35,000 feet and began climbing. A few seconds later the pilot of the small, bullet-shaped craft, Air Force Captain Charles E. Yeager, became the first man officially to fly faster than the speed of sound in level or climbing flight.28
The X–1 was the first of a line of generally successful rocket research airplanes. In November 1953 the Navy’s D-558-II, built by the Douglas Aircraft Company and piloted by A. Scott Crossfield of NACA, broke mach 2, twice sonic speed; but this record stood only until the next month, when Yeager flew the new Bell X–1A to mach 2.5, or approximately 1612 miles per hour. The following summer Major Arthur Murray of the Air Force pushed the X–1A to a new altitude record of 90,000 feet above the Mojave Desert test complex consisting of Edwards Air Force Base and NACA’s High Speed Flight Station. These spectacular research flights, besides banishing the myth that aircraft could not fly past the “sonic barrier,” affected the design and performance of tactical military aircraft.29 In the early fifties, the Air Force and the aircraft industry, profiting from the mountain of NACA research data, were preparing to inaugurate the new “century series” of supersonic jet interceptors.30 And representatives of NACA, the Air Force, and the Navy Bureau of Aeronautics already were planning a new experimental rocket plane, the X–15, to employ the most powerful rocket aircraft motor ever developed and to fly to an altitude of 50 miles, the very edge of space.
Thus less than a decade after the end of the Second World War, airplanes—jet-powered and rocket-propelled—had virtually finished exploring the sensible atmosphere, the region below 80,000 or 90,000 feet. Much work remained for aeronautical scientists and engineers in such areas as airflow, turbulence, engines, and fuels, but researchers in NACA, the military, and the aircraft industry approached the thorniest problems in aeronautics with a confidence grounded in 50 years of progress. Man’s facility in atmospheric flight and his adjustment to the airplane seemed complete. Pilots had mastered some of the most complex moving machines ever contrived, and passengers sat comfortably and safely in
