US Air Force ATF requirement for 750 (now 442) McDonnell Douglas F-15 Eagle replacements incorporating low observables technology and supercruise (supersonic cruise without afterburning); parallel assessment of two new power plants; request for information issued 1981; concept definition studies awarded September 1983 to Boeing, General Dynamics, Grumman, McDonnell Douglas, Northrop and Rockwell; requests for proposals issued September 1985; submissions received by 28 July 1986; USAF selection announced 31 October 1986 of demonstration/validation phase contractors: Lockheed YF-22 and Northrop YF-23; each produced two prototypes and ground-based avionics testbed; first flights of all four prototypes 1990. Competing engine demonstration/validation programmes launched September 1983; ground testing began 1986-87; flightcapable Pratt & Whitney YF119s and General Electric YF120s ordered early 1988; all four aircraft/engine combinations flown.

Lockheed teamed with General Dynamics (Fort Worth) and Boeing Military Airplanes to produce two YF-22 prototypes, civil registrations N22YF (with GE YF120) and N22YX (P&W YF119); USAF serial numbers 87-0700 and 87-0701 assigned, but only 87-0701 applied during second phase of testing, from late 1991. N22YF rolled out at Pahndale 29 August 1990; first flight/ferry to Edwards AFB 29 September 1990; first air refuelling (1 lth sortie) 26 October 1990; thrust vectoring in flight 15 November 1990; anti-spin parachute for high angle of attack tests on 34th to 43rd sorties; flight testing temporarily suspended 28 December 1990; 43 sorties/52 hours 48 minutes. N22YX first flight PalmdaleEdwards 30 October 1990; AIM-9M Sidewinder (28 November 1990) and AIM-120A AMRAAM (20 December 1990) launch demonstrations; achieved Mach 1.8 on 26 December 1990; temporarily grounded after 31 sorties/38 hours 48 minutes, 28 December 1990. Flight test demonstrations included 100ø/s roll rate at 120 knots and supercruise flight in excess of Mach 1.58 without Second (F119-powered) YF-22 taken by road to Palmdale mid-1991; fitted with strain gauges; began further 100 hour test programme 30 October 1991; gathered data on aerodynamic loads, flight control aerodynamic effects, vibration/acoustic fatigue and maximum coefficient of lift; flown by 65 1 lth Test Squadron (F-22 Combined Test Force) of 65 10th Test Wing at Edwards AFB; non-fatal crash landing at Edwards 25 April 1992, following pilot-induced oscillations; total 100 hours 24 minutes in 70 flights since October 1990; non-flyable, but repaired for use as antenna testbed at Rome Air Development Center, Griffiss AFB, New York.

Fabrication of first component for first EMD aircraft (c/n 4001 ) began 8 December 1993 at Boeing's facility in Kent, Washington; assembly of forward fuselage launched at Marietta on 2 November 1995 with start of work on nose landing gear well; assembly work also begun at Fort Worth Summer 1995 with mating of three assemblies that comprise the mid-fuselage of first EMD aircraft taking place in Spring 1996, followed by road transfer of entire section to Marietta in August 1996 for start of final assembly process; first flight planned May 1997; low-rate production decision in August 1998; first production delivery August 2000; high-rate production decision due March 2002.

Low observables configuration and construction; stealth/agility trade-off decided by design team; target thrust/weight ratio 1.4 (achieved ratio 1.2 at T-O weight); greatly improved reliability and maintainability for high sortie-generation rates, including under 20 minute combat turnround time; enhanced survivability through 'first-look, first-shot, first-kill' capability; short T-O and landing distances; supersonic cruise and maneuvering (supercruise) in region of Mach 1.5 without afterburning; internal weapons storage and generous internal fuel; conformal sensors.