Airline Expansion and Innovation (1927 - 1941)

The NACA and the Modern Airliner

Roscoe Turner Airplane

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, one of which hangs in the America by Air exhibition.


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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
Northrop Grumman Corporation

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
NASA

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
NASA

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 Tunnel
NASA

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.

Nineteen Foot Pressure Tunnel
NASA

High-pressure tunnel. 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.