The MD-80 series is a mid-size, medium-range airliner that was introduced in 1980. The design was the second generation of the DC-9 with two rear fuselage-mounted turbofan engines, small, highly efficient wings, and a T-tail. The aircraft has distinctive 5-abreast seating in coach class. It was a lengthened DC-9-50 with a higher maximum take-off weight (MTOW) and a higher fuel capacity. The aircraft series was designed for frequent, short-haul flights for 130 to 172 passengers depending on plane version and seating arrangement.

The development of MD-80 series began in the 1970s as a growth version of the DC-9 Series 50. Availability of new Pratt & Whitney JT8D higher bypass engines drove early studies including designs known as Series 55, Series 50 (Re-fanned Super Stretch), and Series 60. The design effort focused on the Series 55 in August 1977. With the projected entry into service in 1980, the design was marketed as the DC-9 Series 80. Swissair launched the Series 80 in October 1977 with an order for 15 plus an option for five.

The Series 80 featured a fuselage 14 ft 3 in (4.34 m) longer than the DC-9-50. The DC-9 wings were redesigned by adding sections at the wing root and tip for a 28% larger wing. The initial Series 80 first flew October 19, 1979.  It entered service in 1980.

Originally it was certified as a version of the DC-9, but was changed to MD-80 in July 1983, as a marketing move. New versions of the series were initially the MD-81/82/83 and the shortened MD-87, even though their formal certification was DC-9-81/82 etc. Only the MD-88 was given an "MD" certification, as was the later MD-90.

Specifications

	MD-81	MD-82 / MD-88	MD-83	MD-87
Cockpit crew	Two
Seating capacity, typical	172 (1-class) 155 (2 class)			139 (1-class) 130 (2 class)
Length	147 ft 8 in (45.01 m)			130 ft 4 in (39.73 m)
Wingspan	107 ft 8 in (32.82 m)
Wing area	1,209 sq ft (112.3 m2)
Tail height	29 ft 7 in (9.02 m)			30 ft 4 in (9.25 m)
Fuselage width	11 ft (3.35 m)
Cargo capacity	1,253 cu ft (35.5 m3)		1,103 cu ft (31.2 m3)	937 cu ft (26.5 m3)
Empty weight	77,900 lb (35,300 kg)	78,000 lb (35,400 kg)	79,700 lb (36,200 kg)	73,300 lb (33,200 kg)
Maximum take-off weight (MTOW)	140,000 lb (63,500 kg)	149,500 lb (67,800 kg)	160,000 lb (72,600 kg)	140,000 lb (63,500 kg)
Cruising speed	Mach 0.76 (504 mph, 811 km/h)
Maximum range, fully loaded	1,570 nmi (2,910 km; 1,810 mi)	2,050 nmi (3,800 km; 2,360 mi)	2,500 nmi (4,600 km; 2,900 mi)	2,370 nmi (4,390 km; 2,730 mi)
Runway length requirement	5,000 ft (1,500 m) dry, or 5,700 ft (1,700 m) for wet runway
Fuel capacity	5,850 US gal (22,100 L)	5,850 US gal (22,100 L)	7,000 US gal (26,000 L)	5,840 US gal (22,100 L)
Engines (×2)	Pratt & Whitney JT8D-200 series
Thrust (×2)	18,500–21,000 lbf (82–93 kN)

Source: Wikipedia