Программа ATF: Разработка истребителя нового поколения ВВС США.

USAF demonstration and validation program

The Advanced Tactical Fighter (ATF) was a program undertaken by the United States Air Force to develop a next generation air superiority fighter to counter emerging worldwide threats, including Soviet Sukhoi Su 27 and Mikoyan MiG 29 fighters under development in the 1980s, Beriev A 50 airborne warning and control system (AWACS), and increasingly sophisticated surface to air missile systems. Lockheed and Northrop were selected in 1986 to respectively develop the YF 22 and the YF 23 technology demonstrator aircraft for the program's demonstration and validation (Dem/Val) phase. These aircraft were evaluated in 1991 and the Lockheed design was selected for full scale development, or engineering and manufacturing development (EMD), and later developed into the F 22 Raptor for production and operational service.

In 1981, USAF began forming requirements for a new air superiority fighter intended to replace the capability of the F 15 Eagle. In May 1981 a request for information (RFI) for the Advanced Tactical Fighter (ATF) was published by the Air Force Aeronautical Systems Division (ASD), followed by another RFI for the ATF propulsion systems in June. Design concepts were provided by defense contractors. The common areas among the concepts were stealth, STOL and supercruise. It was envisioned that the ATF would incorporate emerging technologies including advanced alloys and composite material, advanced fly by wire flight control systems, higher power propulsion systems, and low observable, or stealth technology. In September 1983, study contracts were awarded to seven airframe manufacturers for further definition of their designs. By late 1984, ATF requirements had settled on a fighter with a maximum takeoff weight of , a mission radius of 800 mile (1287 km), supercruise speed of Mach 1.4–1.5 and the ability to use a 2000 feet (610 m) runway. A request for proposals (RFP) for the fighter's engine, called the Joint Advanced Fighter Engine (JAFE), was released in May 1983. Pratt & Whitney and General Electric received contracts for the development and production of prototype engines in September 1983.

A request for proposals (RFP) for the fighter was issued in September 1985. The RFP would see some changes after its first release; in December 1985, stealth requirements were drastically increased and in May 1986, the Air Force changed the RFP so that final selection would involve flying prototypes. Additionally, the U. S. Navy, under the Navalized Advanced Tactical Fighter (NATF) program, eventually announced that it would use an ATF derivative to replace its F 14 Tomcat. In July 1986, proposals were provided by Boeing, General Dynamics, Lockheed, Northrop, and McDonnell Douglas. During the demonstration/validation phase of development, the USAF focused on system engineering, technology development plans, and risk reduction over point aircraft designs. This was reflected in the prototyping goals, where both the YF 22 and YF 23 were to be "best effort" vehicles not meant to perform a competitive flyoff or represent a production aircraft that meets every requirement, but to demonstrate the viability of its concept and the ability of contractors to meet predicted performance. Both contractor teams conducted performance and cost trade studies and presented them in system requirement reviews (SRRs) with the USAF. This enabled the USAF to adjust ATF requirements and delete ones that were significant weight and cost drivers while having marginal operational value. Because of the added weight for thrust vectoring/reversing nozzles and related systems on the F 15 S/MTD research aircraft, the Air Force changed the runway length requirement to 3000 feet (914 m) and removed the thrust reversers on the ATF in late 1987. As avionics was a significant cost driver, side looking radars were deleted, and the dedicated infrared search and track (IRST) system was downgraded from requirement to goal. The ejection seat requirement was downgraded from a fresh design to the existing McDonnell Douglas ACES II. Despite efforts by the contractor teams to rein in weight, the takeoff gross weight estimate was increased from to , resulting in engine thrust requirement increasing from to class. Two examples of each prototype were built for the Demonstration Validation phase: one with General Electric YF120 engines, the other with Pratt & Whitney YF119 engines. The first YF 23 made its maiden flight on 27 August 1990 and the first YF 22 first flew on 29 September 1990. Flight testing began afterwards and added the second aircraft for each competitor in late October 1990. The YF 22 with GE engines achieved Mach 1.58 in supercruise. Flight testing continued until December 1990. Following flight testing, the contractor teams submitted proposals for ATF production.

Following a review of the flight test results and proposals, the Air Force announced the Lockheed YF 22 with Pratt & Whitney engines as the competition winner for full scale development, or engineering and manufacturing development (EMD), on 23 April 1991. While both designs met or exceeded all performance requirements, the YF 23 was stealthier and faster, but the YF 22 was more agile. The US Navy had begun considering a version of the ATF called Navy Advanced Tactical Fighter (NATF) in 1986. It has been speculated in the aviation press that the YF 22 was also seen as more adaptable to the NATF. The Navy abandoned NATF by 1992. The Lockheed team was awarded the EMD contract to develop and build the Advanced Tactical Fighter in August 1991. The YF 22 was modified into the production F 22 Raptor version, which first flew in September 1997 and entered service in December 2005. The Northrop YF 23 design was later considered by the company for modification as a bomber, but the proposals have not come to fruition.