MARIETTA, Ga. AFPN (Jan. 20, 1999) -- F-22 Raptors 4000 & 4004 undergo final assembly at Lockheed Martin Aeronautical Systems here. Both aircraft will join the F-22 test program next year. Raptor 4000 will support ground test activities here, while Raptor 4004 will join the flight test fleet at Edwards Air Force Base, Calif., to test and validate the Raptor's integrated avionics software suite. The F-22 Raptor is being put through the most extensive and sophisticated testing of any combat aircraft ever developed. (Article Courtesy USAF Press Release)