Page:This New Ocean, a history of Project Mercury, Swenson, Grimwood, Alexander (NASA SP-4201).djvu/25

 increase in the firepower of aircraft, but well before the single B—29 dropped the single five-ton bomb on Hiroshima, long-range bomber fleets carrying conventional TNT explosives and incendiaries had radically altered the nature of war.

The frantic race in military technology developing in the postwar years between the United States and the Soviet Union produced a remarkable acceleration in the evolution of the airplane. Jet-propelled interceptors, increasingly rakish in appearance by comparison with their staid propeller-driven ancestors, flew ever faster, higher, and farther. Following the recommendations of a series of blue-ribbon scientific advisory groups, the Defense Department and the newly independent Air Force made the Strategic Air Command, with its thousands of huge manned bombers, the first line of American defense in the late forties and early fifties. To many people the intercontinental bomber, carrying fission and (after 1954) hydrogen-fusion weapons, capable of circumnavigating the globe nonstop with mid-air refueling, looked like the “ultimate weapon” men had sought since the beginning of human conflict.

Working under the incessant demands of the cold-war years, NACA continued to pioneer in applied aeronautical research. By 1946 the NACA staff had grown to about 6800, its annual budget was in the vicinity of $40 million, and its facilities were valued at more than $200 million. Although Chairman Hunsaker and others on the Main Committee felt that NACA's principal mission should be inquiry into the fundamentals of aeronautics, the military services and the aircraft industry continued to rely on NACA as a problem-solving agency. The pressure for "quick fixes" persisted as the Korean War intensified requirements for work on specific aircraft problems.

The outstanding general impediment to aeronautical progress, however, continued to be the so-called "sonic barrier," a region near the speed of sound (approximately 750 miles per hour at sea level, 660 miles per hour above 40,000 feet) wherein an aircraft encounters compressibility phenomena in fluid dynamics, or the "piling up" of air molecules. A serious technical obstacle to high-speed research in the postwar years was the choking effect experienced in wind tunnels during attempts to simulate flight conditions in the transonic range (600-800 miles per hour). A wind tunnel constructed at Langley employing the slotted-throat principle to overcome the choking phenomenon did not begin operation until 1951, and a series of NACA and Air Force supersonic tunnels, authorized by Congress under the Unitary Plan Act of 1949, was not completed until the mid-fifties. NACA investigators had to use other methods for extensive transonic research. One was a falling-body technique, in which airplane models equipped with radio-telemetry apparatus were dropped from bombers at high altitudes. Another was the firing of small solid-propellant rockets to gather data on various aerodynamic shapes accelerated past mach, the speed of sound. Many of these tests supported military missile studies. The rocket firings were carried out at the Pilotless Aircraft Research Station, a facility set up by the Langley laboratory on Wallops Island, off the Virginia coast, in the spring of 1945. The 10