What is Boeing 720?
{|{{Infobox aircraft begin | name = Boeing 720 | image = File:Trans Polar Boeing 720 Söderström.jpg | caption = Trans Polar Boeing 720 landing at Stockholm-Arlanda Airport in June 1970 }}{{Infobox aircraft type | type = Narrow-body [[jet airliner]] | national origin = United States | manufacturer = [[Boeing Commercial Airplanes|Boeing Airplane Company]] | first flight = November 23, 1959 | introduced = July 5, 1960 with [[United Airlines]] | retired = | status = Retired | primary user = [[United Airlines]] | more users = Western Airlines <br>[[Eastern Air Lines]] <br>[[Northwest Airlines]] | produced = 1958–1967 | number built = 154<ref name=Angelucci_p346/> | unit cost = | developed from = [[Boeing 707]] | variants with their own articles = }} |} The '''Boeing 720''' is a [[Jet aircraft|jet airliner]]. It has two rows of seats, which means that it is a narrow-body airliner. It has four engines. The Boeing 720 was designed by [[Boeing Commercial Airplanes|Boeing]] in the 1950s. It was based on the [[Boeing 707]], but the 720 is shorter and cannot fly as far. The 720 first took off in November 1959. [[Airline]]s began to use it in July 1960. Two versions of the plane were made. The first one had Pratt & Whitney JT3C [[turbojet]] engines and was first used in 1960. The second one is called the 720B, and it has Pratt & Whitney JT3D [[turbofan]] engines. It was first used in 1961. Some 720s were changed to 720Bs. Only 154 Boeing 720s were built, but it still made Boeing a lot of money because it did not cost a lot to design. The Boeing 720 was replaced by the [[Boeing 727]]. ==Designing== ===Shorter range 707=== [[File:MEA Boeing 720 Marmet-2.jpg|thumb|left|A [[Middle East Airlines]] Boeing 720 in April 1982]] Boeing said it would make a new type of [[Boeing 707]] in July 1957.<ref name=Angelucci_p346>Angelucci, Enzo; Paolo Matricardi and Adriano Zannino. ''The Illustrated Encyclopedia of Civil Aircraft: From Leonardo da Vinci to the Present'', p. 346. Edison, New Jersey US: Chartwell Books, 2001. {{ISBN|0-78