The Boeing Model 247 was considered the first such aircraft to fully incorporate advances such as all-metal (anodized aluminium) semimonocoque construction, a fully cantilevered wing and retractable landing gear. Other advanced features included control surface trim tabs, an autopilot and de-icing boots for the wings and tailplane. "Ordered off the drawing board", the 247 first flew on February 8, 1933, and entered service later that year. Subsequent development in airliner design saw engines and airframes becoming larger and four-engined designs emerged, but no significant changes to this basic formula appeared until cabin pressurization and high altitude cruise were introduced in 1940, with the Boeing 307 Stratoliner. The 247 was the first twin-engined passenger transport able to fly on one engine. With controllable pitch propellers (standard equipment on the 247D), the 247 could maintain 11,500 feet (3,500 m) at maximum gross takeoff weight. Its combination of features set the standard for the Douglas DC-1 and other airliners before World War II. During the 1930s, aircraft designs were often proven in air races and other aerial contests. A modified 247D was entered in the MacRobertson Air Race from England to Australia, flown by Colonel Roscoe Turner and Clyde Pangborn. The 247, race number "57," was essentially a production model but all airliner furnishings were removed to accommodate eight additional fuselage fuel tanks. The MacRobertson Air Race attracted aircraft entries from all over the globe, including prototypes as well as established production types, with the gruelling course considered an excellent proving ground as well as an opportunity to gain worldwide attention. Turner and Pangborn came in second place in the transport section (and third overall), behind the Boeing 247's eventual rival, the new Douglas DC-2. A total of 75 were built over seven variants. The specifications below are for the 247D variant. For more information on hte development, design and operational history of the 247, click here.
