The 20-foot radius of the Propeller Research Tunnel enabled testing on a full-sized airplane, and NACA engineer Fred E. Weick and his staff, by November 1928, had produced a cowling that significantly reduced drag and, in directing rapid airflow around the engine’s hottest components, actually improved cooling. When Weick fitted his cowling around the engine of a Curtiss Hawk AT-5A biplane, the result was astonishing: The Hawk’s top speed increased from 118 to 137 miles per hour, a 16 percent increase.
The NACA cowling was a crowning achievement for the NACA and its Langley technicians, reducing overall drag by as much as 60 percent and saving the aircraft industry millions of dollars. In 1929, the cowling earned Weick and Langley the first Robert J. Collier Trophy, an honor bestowed annually by the National Aeronautics Association for the most significant contributions to aeronautics research. By 1932, virtually every radial-engine aircraft was equipped with a variant of the NACA cowling.
The NACA emerged from the 1920s a renowned and influential center of aeronautical research, and throughout the next decade the findings of its technicians continued to alter the look and feel of modern aircraft. Testing at Langley revealed, for example, that fixed landing gear accounted for nearly 40 percent of an aircraft’s total drag; that dual engines were best mounted as part of the wings’ overall structures; that positioning wings on the lower part of the fuselage improved lift and eliminated the need for heavy struts. Aircraft manufacturers adapted in accordance with these new findings, producing low-slung monoplanes with retractable landing gear and streamlined engine nacelles built into the wings.
Langley engineers also set out to examine the increasingly strenuous task of piloting transports and bombers that had grown larger and heavier – and therefore difficult to maneuver and slow to respond. The work of quantifying the “feel” and responsiveness of aircraft controls was a tall order, but carefully designed evaluations of several large aircraft, including the Douglas DC-3 transport plane and the experimental DC-4E, yielded design recommendations that led to important changes in specifications for the control and stability characteristics of military airplanes.
Another influential area of research was the laminar flow wing developed at Langley and used in the design of the North American P-51 Mustang fighter, perhaps the best fighter flown by the Army Air Forces during World War II.
As war overtook Europe, NACA representative John Jay Ide sent frequent dispatches describing research and development facilities in France, Italy, Russia, and especially Germany, being built to surpass NACA facilities. After touring the continent in 1936, George Lewis urged Congress to pass a supplemental appropriation for a new propeller research tunnel. He also requested the formation of a special committee on the Relation of the NACA to National Defense in Time of War.
This committee, chaired by Maj. Gen. Oscar Westover, chief of the Army Air Corps, recommended in its 1938 report that the NACA build a laboratory on the West Coast or in the interior, to reduce the vulnerability associated with keeping the government’s aeronautical expertise concentrated in one location. The laboratory that eventually resulted, located at a longtime naval airship station at Moffett Field on the shore of San Francisco Bay, was named in honor of Dr. Joseph Ames, the founding member of the NACA who had resigned as executive committee chair in 1936. The Ames Aeronautical Laboratory opened in 1940.
While Ames was being authorized by Congress, a group of advocates, bolstered by famed aviation pioneer Charles Lindbergh, took up the cause for a third NACA research center, one focused on engine research that would help American aircraft compete with the high-performance, liquid-cooled engine designs of German, French, and British military planes. In June 1940 – the month in which France capitulated to Germany – Congress appropriated funds for the construction of the NACA Aircraft Engine Research Laboratory in Cleveland, Ohio.
Cleveland’s Flight Research Building opened at the end of 1941. The laboratory’s first director, Edward Sharp, hastened to Ohio after Japan’s attack on Pearl Harbor – but with no administrative space yet available, Sharp and his technical assistants set themselves up at a nearby farmhouse and got down to work. The NACA had put the pieces in place – just in time, as it turned out – to lead a new generation of advances in aeronautical research.
This article first appeared in the NACA/NASA: Celebrating a Century of Innovation, Exploration, and Discovery in Flight and Space, 1915-2015 publication.