Created in 1915 to supervise and direct American aeronautical research, the National Advisory Committee for Aeronautics (NACA) helped solve some of flight's most difficult problems.
In the late 1950s, the need for astronautical research increased as the Space Race between the Soviet Union and the United States began to heat up. In response, National Aeronautics and Space Administration, or NASA was created and the NACA was absorbed into it. While many are familiar with NASA for its work in spaceflight, it also continues to carry out important aeronautical research just as the NACA did.
Early Aircraft Technology
Europeans led the world in aeronautics after World War I. Concerned the United States was rapidly falling behind Europe in aeronautical technology, Congress created the National Advisory Committee for Aeronautics, or NACA. By the end of the 1920s, the NACA’s efforts were bearing fruit.
Developing the Modern Airliner
The National Advisory Committee for Aeronautics was largely responsible for developing many technologies that led to the creation of modern airliners. A revolutionary new generation of airliners began appearing in the early 1930s. Fast and efficient, they featured all-metal, monocoque and stressed-skin construction, cantilevered wings, retractable landing gear, cowled air-cooled engines, and variable-pitch propellers-technologies developed by the NACA, the military, and private industry.
The first of these modern airliners was the Boeing 247. It revolutionized air transportation when it entered service with United Air Lines in 1933. It could carry 10 passengers, fly 50 percent faster than the Ford Tri-Motor, and could cross the country in less than 20 hours. Its innovative design launched a new generation of commercial airliners, notably the Douglas DC-2.
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.
With a throat 6 meters (20 feet) across, this tunnel enabled engineers to test full-size aircraft fuselages with their propellers attached. The NACA 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.
The testing space within this huge wind tunnel was the size of a small two story house, allowing engineers to test full-size aircraft. The NACA 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.
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.
Opened in 1939, this tunnel was the first to combine large size and high pressure in one facility. Engineers used it to develop a new generation of high-performance military aircraft.
Results: NACA's Contributions to the Modern Airliner
Based on the extensive research carried out by the National Advisory Committee for Aeronautics, several key developments were made in the production of a modern airliner. Learn about them below.
NACA engineers developed many new families of airfoils (wing cross sections), which were used to design most American and many foreign aircraft. Research on high-speed airfoils also reshaped the design of aircraft propellers.
The NACA's most important contribution to the modern airliner was the engine cowl. Enveloping the front of an engine, it increased aircraft speed by smoothing the airflow over the cylinders, while allowing for better engine cooling. For producing the first practical full-cowl design (shown here), the NACA received the prestigious Collier Trophy.
NACA research showed that locating engines directly in front of the wing, with the propellers far in front of the leading edge, reduced drag and enhanced lift and engine efficiency. The gains proved so great that aircraft designers could eliminate nose-mounted engines.
The NACA spread the results of its own and other research through publications. This information profoundly influenced American aviation technology and inspired many changes to civil and military aircraft, from flush rivets, tighter construction tolerances, and retractable landing gear to overall fuselage and wing designs.
In April 1942, a young undergraduate, Stefan Cavallo, graduated from New York University with a degree in aeronautical engineering. Before World War II, he learned to fly and earned a civilian pilot’s license with the Civilian Pilot Training Program and he was to enter the Army Air Corps as a pilot cadet after he graduated. Even though the military was in desperate need of pilots with the nation at war, Cavallo’s unique resume made him even more valuable to the National Advisory Committee for Aeronautics (NACA).
While propeller-driven airliners were enjoying their "golden age," the NACA was doing research that would help create a new generation of high-speed passenger planes.
As the Cold War took hold after World War II, the United States anxiously stepped up aeronautical research to enhance the nation's security in an uncertain world. The National Advisory Committee for Aeronautics (NACA) began to focus on the challenges of transonic and supersonic flight.
Although intended primarily for military purposes, the results of the NACA's research greatly benefited the future development of high-speed airliners. As proof of its pioneering work during this time, the NACA won the coveted Collier Trophy four times.
While today's jet airliners fly most efficiently at high subsonic speed, air flows over their wings at transonic and even supersonic speeds. To make high-subsonic flight safe and efficient, aircraft companies developing jetliners in the 1950s depended upon the NACA's pioneering transonic research.
On October 14, 1947, Capt. Charles E. "Chuck" Yeager piloted the rocket-powered Bell X-1 to Mach 1.06, destroying the myth of the "sound barrier." Working with the Air Force and Bell Aircraft, the NACA made critical contributions to the design of the wings, the fuselage, and the crucial adjustable stabilizer. The NACA used the X-1 to study the dangerous problem of air compressibility and powerful shock wave formation during transonic flight.
The NACA and the Navy designed and tested the Douglas D-558-1 Skystreak. They used it to study the difficulties of transonic flight, during which the airflow over the wings becomes unpredictable and unstable. Because it was jet powered, the Skystreak could collect data for much longer periods than the rocket-powered Bell X-1, which was faster but had a short range.
Gathering test data about transonic flight was difficult, because conventional wind tunnels would "choke" on shock waves bouncing along their walls. In 1950, John Stack and his associates at the NACA's Langley Memorial Aeronautical Laboratory built the first "slotted" wind tunnel, which resolved this problem.
The NACA and the Navy developed the Douglas D-558-2 Skyrocket to learn more about the characteristics of swept-wing aircraft. Flight testing revealed the problem of the nose pitching up at high speeds, which they solved, paving the way for swept-wing military and civilian aircraft. On November 20, 1953, NACA test pilot A. Scott Crossfield became the first to fly faster than twice the speed of sound in the Skyrocket.
The Cold War pushed the United States into expanding all its scientific research. One result was the NACA's entry into astronautical research. On October 1, 1958, almost one year after the Soviet Union orbited the first artificial satellite, Sputnik 1, the National Aeronautics and Space Administration (NASA) was formed, absorbing the NACA. Despite its focus on spaceflight, NASA continues to pioneer new discoveries in aeronautics.