S-duct in the context of "Boeing 727"

The Boeing 727 is an American narrow-body airliner that was developed and produced by Boeing Commercial Airplanes.After the heavier 707 quad-jet was introduced in 1958, Boeing addressed the demand for shorter flight lengths from smaller airports.On December 5, 1960, the 727 was launched with 40 orders each from United Airlines and Eastern Air Lines.The first 727-100 rolled out on November 27, 1962, first flew on February 9, 1963, and entered service with Eastern on February 1, 1964.

The only trijet aircraft to be produced by Boeing, the 727 is powered by three Pratt & Whitney JT8D low-bypass turbofans below a T-tail, one on each side of the rear fuselage and a center one fed through an S-duct below the tail.It shares its six-abreast upper fuselage cross-section and cockpit with the 707 that was also later used on the 737.The 133-foot-long (41 m) 727-100 typically carries 106 passengers in two classes over 2,250 nautical miles [nmi] (4,170 km; 2,590 mi), or 129 in a single class.Launched in 1965, the stretched 727-200 flew in July 1967 and entered service with Northeast Airlines that December.The 20 ft (6.1 m) longer variant typically carries 134 passengers in two classes over 2,550 nmi (4,720 km; 2,930 mi), or 155 in a single class.A freighter and a "Quick Change" convertible version were also offered.