The DC-9 was Douglas answer on Boeing's 737. Like no other aircraft it has been modified up to the present, the newest aircraft which bases on the DC-9 is the Boeing 717. The DC-9 was presented by Douglas in 1962 and the production was started without any orders. But the first one came soon from Delta Air Lines. The first flight of the DC-9 in Long Beach was on February 25th 1965, the first delivery to Delta was in November.
The DC-9 has the same engines as Boeings first 737 versions (Pratt&Whitney JT8D), however Douglas installed them at the tail. The T-shaped tail made possible that the DC-9 didn't need much runway length for take off. Compared with the 737 the fuselage of the DC-9 is a bit slimmer and a 2+3 seating is used. The fuselage was constructed for an easy stretching of the DC-9, what should make possible a better flexibility in the aircraft family. A characteristic feature was the two-men-flight deck of the DC-9. The DC-9 was very successful as a military aircraft, too.
The standard version was the DC-9-10, which can transport up to 90 passengers. There was version -20 with more powerful engines, too. In early 1965 Eastern Airlines ordered a stretched DC-9 which became DC-9-30. It was stretched about five metres compared with the standard version. This version is able to transport up to 115 passengers. In 1968 the DC-9-40 with more powerful engines and more seats was launched, after it had been demanded especially by SAS. In 1975 the last version of the DC-9 was presented: the DC-9-50 with new engines.It was stretched another time and is able to keep up to 139 passengers. Version -50 got a new modern cabin design, too.
In October 1972 the 976th and last DC-9 was delivered. It was succeeded by the DC-9 Super 80, which was later renamed into McDonnell Douglas MD-80.