Prior to its selection as winner of what was then known as the Advanced Tactical Fighter (ATF) competition, the F-22 team conducted a 54-month demonstration/ validation (dem/val) program.
The effort involved the design, construction and flight testing of two YF-22 prototype aircraft. Two prototype engines, the Pratt & Whitney YF119 and General Electric YF120, also were developed and tested during the program. The dem/val program was completed in December 1990.

Much of that work was performed at Boeing in Seattle, Lockheed (now known as Lockheed Martin) facilities in Burbank, Calif., and at General Dynamics' Fort Worth, Texas, facilities (now known as Lockheed Martin Tactical Aircraft Systems). The prototypes were assembled in Lockheed's Palmdale, Calif., facility and made their maiden flight from there. Since that time Lockheed's program management and aircraft assembly operations have moved to Marietta, Ga., for the EMD and production phases.

A $9.55 billion contract for Engineering and Manufacturing Development (EMD) of the F-22 was awarded to the industry team of Boeing and Lockheed Martin in August 1991. Contract
changes since then have elevated the contract value to approximately $11 billion. Under terms of the contract, the F-22 team will complete the design of the aircraft, produce production tooling for the program, and build and test nine flightworthy and
two ground-test aircraft.

In February 1995, the Air Force customer approved the final design of the F-22 air vehicle and confirmed that the program was ready to proceed to fabrication and assembly. The Air Force plans to produce 339 F-22s, and production is scheduled to run through 2013.