Boeing 247

…accepted until 1933, when the Boeing 247-D entered service. The twin-engine design of the latter established the foundation of modern air transport.

(see Boeing Company), produced its Model 247, an all-metal, twin-engine, low-wing monoplane first flown in 1933 and regarded as the first “modern” airliner. Although the aircraft was sought by most American carriers, Boeing restricted sales of 247s until the order for its sister company, United Airlines, had been filled. This…

…introduction of the Boeing Company Model 247 airliner, which cruised at about 180 miles (290 km) per hour and entered service with United Airlines, Inc., in 1933. With its all-metal stressed-skin construction (which used the metal skin covering itself to carry aerodynamic loads), retractable gear, two 550-horsepower Pratt & Whitney…