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Research: NACA Wind Tunnels
Wind tunnels were the primary research tools of aeronautical engineers. The NACA built four innovative tunnels at their Langley Aeronautical Laboratory in Virginia from 1927 to 1939 that led to breakthroughs in aircraft design.
John K. "Jack" Northrop left Lockheed Aircraft in 1928 to start a company for producing metal aircraft. His first design was the Northrop Alpha, which blended a strong, lightweight, cantilevered stressed-skin wing with a metal monococque fuselage. The Alpha so impressed William Boeing that he bought Northrop's Company. Jack Northrop's fervent advocacy of all-metal monocoque aircraft had a lasting impact on U.S. aircraft designs.
Propeller research tunnel. With a throat 6 meters (20 feet) across, this tunnel enabled engineers to test full-size aircraft fuselages with their propellers attached. They discovered that fixed landing gear and exposed engine cylinders caused enormous amounts of drag, and that aircraft performed better when their engines were positioned directly in front of the wing.
Full-scale tunnel. The testing space within this huge wind tunnel was the size of a small two story house, allowing engineers to test full-size aircraft. They found that external struts, scoops, and antennas impaired performance. Nearly every high-performance U.S. aircraft used during World War II was tested in this tunnel.
High-speed wind tunnel. This tunnel could produce air speeds of 925 kilometers (575 miles) per hour. Although most aircraft flew only about a third of that speed, their propeller tips approached the speed of sound. The tunnel demonstrated that rivet heads and other surface irregularities produced significant drag. |