Boeing 247

The Boeing Model 247 was an early American airliner and one of the first to bring together an all-metal semi-monocoque structure, a fully cantilevered wing and retractable landing gear. It also carried control surface trim tabs, an autopilot and de-icing boots on the wings and tail. It was faster than the best American fighter of its day, the open-cockpit Boeing P-12, and could keep flying on one engine. The 247 first flew on 8 February 1933 and entered service later that year, and 75 were built before the Douglas DC-2 and DC-3 overtook it, even though many of its features became the norm for later airliners.