Cockpit of the 1939 Douglas DC-3 Airplane, Photographed in 2003

The Douglas DC-3, first flown in 1935, made use of several advancements in aircraft design. Internal bracing for the wings allowed for streamlined surfaces. Engine cowlings and retractable landing gear reduced drag. Improved engines increased range. The result was a rugged, stable airplane easy for pilots to handle. By 1939, DC-3 planes carried 75 percent of U.S. air travelers.