The Pratt & Whitney JT8D is a low-bypass (0.96 to 1) turbofan engine introduced by Pratt & Whitney in February 1963 with the inaugural flight of the Boeing 727. It was a modification of the Pratt & Whitney J52 turbojet engine which powered the US Navy A-6 Intruder and A-4 Skyhawk attack aircraft. Eight models comprise the JT8D standard engine family, covering the thrust range from 12,250 to 17,400 pounds-force (62 to 77 kN), and power 727, 737-100/200, and DC-9. The updated JT8D-200 family, covering the 18,900 to 21,000 pounds-force (84 to 93 kN), powers the MD-80 and re-engined Super 27 aircraft. The Volvo RM8 was license-built in Sweden for the Saab 37 Viggen fighter. Pratt & Whitney also sells static versions for powerplant and ship propulsion as the FT8.