The Advanced Tactical Fighter (ATF) was a program undertaken by the United States Air Force to develop a next-generation air superiority fighter to replace the F-15 Eagle. The proposed fighter was intended to counter emerging worldwide threats in the 1980s, including Soviet Sukhoi Su-27 and Mikoyan MiG-29 fighters under development, Beriev A-50 airborne warning and control systems (AWACS), and increasingly sophisticated surface-to-air missile systems. The program resulted in the F-22 Raptor.
The ATF would make a leap in performance and capability by taking advantage of emerging technologies, including advanced avionics and flight control systems, more powerful propulsion systems, and stealth technology. Lockheed and Northrop were selected in 1986 as finalists for the program's Demonstration and Validation (Dem/Val) phase. They would be the lead contractors to respectively develop the YF-22 and YF-23 technology demonstrator prototypes, the associated avionics prototypes, and the system specification; the prototype aircraft were flight tested in 1990.
After evaluations, the Lockheed team was selected in 1991 for ATF full-scale development, or Engineering and Manufacturing Development (EMD). The Lockheed team developed their design into the F-22 Raptor, which first flew in 1997, for production and operational service; a naval version of the ATF (called NATF) was considered as an F-14 Tomcat replacement but was later canceled due to costs.
Background
Although the term "Advanced Tactical Fighter" (ATF) appeared in U.S. Air Force (USAF) parlance as far back as 1971 to describe potential future tactical aircraft – initially an air-to-surface attack aircraft – the program that would eventually result in the F-22 began in 1981.Aronstein and Hirschberg 1998, p. 5. This was motivated by the shift in U.S. military doctrine in the late Cold War towards striking the enemy's rear echelons as eventually outlined in the AirLand Battle concept, as well as intelligence reports of multiple emerging worldwide threats emanating from the Soviet Union. Between 1977 and 1979, American satellite photographs of the "Ram-K" and "Ram-L" fighter prototypes at Ramenskoye air base in Zhukovsky—later identified as the Su-27 "Flanker" and the MiG-29 "Fulcrum" respectively—indicated that a new generation of Soviet fighter aircraft comparable to the recently introduced F-15 Eagle and F-16 Fighting Falcon would soon enter service.Aronstein and Hirschberg 1998, pp. 17–18.
Also concerning were Soviet reports of "look-down/shoot-down" capability being introduced on an advanced MiG-25 derivative, later revealed to be the MiG-31 "Foxhound", as well as the appearance of an Il-76-based airborne warning and control system (AWACS) aircraft called the A-50 "Mainstay". These systems, revealed in 1978, greatly reduced the effectiveness and survivability of low-altitude penetration. Furthermore, experience and data from the Vietnam War and the more recent 1973 Arab-Israeli war demonstrated the increasing lethality and sophistication of Soviet surface-to-air missile systems.Aronstein and Hirschberg 1998, p. 12.Metz 2017, pp. 8–10.Miller 2005, pp. 10–11.
Program history Concept development
In 1981, the USAF began forming requirements for the ATF, eventually codenamed "Senior Sky". In May, a request for information (RFI) to the aerospace industry was published by the USAF Aeronautical Systems Division (ASD), followed by another RFI for the ATF propulsion systems in June. In response, a number of aerospace defense contractors provided design concepts for analysis by the ASD, which released their final report in December 1982.Aronstein and Hirschberg 1998, pp. 30-33. During this time, the ASD also established an internal ATF Concept Development Team (CDT) in October 1982 to manage concept development studies. As the ATF was still early in its requirements definition, including whether the aircraft should be focused on air-to-air or air-to-surface, there was great variety in the RFI responses; the submitted designs generally fell into four concepts.Aronstein and Hirschberg 1998, p. 40.
Numbers Fighter (N): Lightweight, low-cost design trading lower individual capability for quantity. Supersonic Cruise and Maneuver (SCM): Approximately takeoff weight fighter with high maneuverability and specific excess power at transonic and supersonic speeds. Subsonic Low Observable (SLO): An internal ASD concept that sacrificed fighter-like performance and speed for low radar cross-section and infrared signature. High-Mach/High-Altitude (HI): Large and fast missileer aircraft over at takeoff intended to operate well above Mach 2 and .
Further analysis by ASD would indicate that the best air-to-surface concept was SLO, while the best air-to-air concept was SCM; neither N nor HI were rated highly, and responses from contractors also broadly agreed on avoiding either extremes of the quality-versus-quantity spectrum. Even with the variety of the submitted designs in the responses, the common areas among some or all the concepts were reduced observability, or stealth (though not to the extent of the final requirements), short takeoff and landing (STOL) and sustained supersonic cruise without afterburners, or supercruise.Sweetman 1991, pp. 12–13.Aronstein and Hirschberg 1998, pp. 42-45. It was envisioned that the ATF would incorporate emerging technologies to include advanced alloys and composite material, advanced avionics and fly-by-wire flight control systems, higher power propulsion systems, and low-observable, or stealth technology.Sweetman 1991, p. 10-11, 21.Hehs 1998, Part 1.
By October 1983, the ATF Concept Development Team had become the System Program Office (SPO) led by Colonel Albert C. Piccirillo at Wright-Patterson Air Force Base.Aronstein and Hirschberg 1998, pp. 56-57. After discussions with Tactical Air Command (TAC), the CDT/SPO determined that the ATF should focus on air-to-air missions. The air-to-surface missions would be handled by the upgraded F-111 variants, the upcoming Dual-Role Fighter (DRF), (formerly the Enhanced Tactical Fighter, which would result in the F-15E Strike Eagle) as well as the then-classified F-117 Nighthawk ("Senior Trend"), while the air-to-air threat from the new Soviet fighters and AWACS remained. Additionally, a multirole aircraft designed to effectively perform both air-to-air and air-to-surface missions was considered too costly; as with ASD and industry responses, TAC did not want the ATF to be at either extremes of the quality-versus-quantity spectrum. The ATF would thus be a new air superiority fighter in the vein of the SCM concept with outstanding aerodynamic performance, and intended to replace the capability of the F-15 Eagle by the 1990s. In the potential scenario of a Soviet and Warsaw Pact invasion in Central Europe, the ATF was envisaged to launch from bases in central England and support the air-land battle by performing offensive and defensive counter-air missions against the Soviet air-to-air threats. This would then allow the DRF and other strike aircraft to perform air interdiction against ground targets.Aronstein and Hirschberg 1998, pp. 45-54, 72.
With the ATF's mission now focused on air-to-air, another round of requests were sent to the industry for concept exploration and study contracts were awarded to seven airframe manufacturers for further definition of their designs. A request for proposals (RFP) for the fighter's engine, initially called the Joint Advanced Fighter Engine (JAFE) due to its potential joint application with the U.S. Navy's short-lived Advanced Carrier-Based Multirole Fighter (VFMX), was released in May 1983 to Allison, General Electric, and Pratt & Whitney. In September 1983, General Electric and Pratt & Whitney each received $202 million contracts (~$ in ) for the development and production of prototype engines; Allison chose to not submit a bid due to technical problems with their advanced development demonstrators.Sweetman 1991, p. 13.Aronstein and Hirschberg 1998, pp. 207-208. The SPO also expected that avionics would be a major component of the ATF in light of rapidly advancing semiconductor technology; requests for advanced avionics components such as the integrated electronic warfare system were sent out that November.Aronstein and Hirschberg 1998, p. 61.
During this time, the SPO took an increasing interest in stealth as results from classified special access or "black world" programs such as the Have Blue/F-117, Tacit Blue, and the Advanced Technology Bomber (ATB) program (which would result in the B-2 Spirit, or "Senior Ice") promised greatly reduced radar cross sections (RCS) that were orders of magnitude smaller than existing aircraft. The ATF requirements would place increasing emphasis on stealth to improve survivability over the course of concept exploration, while still demanding fighter-like speed and maneuverability; the combination of low observables with the SCM concept was expected to greatly reduce the lethal zone of hostile surface-to-air missiles. As a result of stealth technology, the design details became "black" even though the ATF was a publicly acknowledged program. By late 1984, the SPO had settled on the ATF requirements and released the Statement of Operational Need (SON). The SON called for a fighter with a takeoff gross weight of , a mission radius of mixed subsonic/supersonic or subsonic, supercruise speed of Mach 1.4–1.5, the ability to use a runway, and signature reduction, particularly in the frontal sector.Miller 2005, p. 13.Aronstein and Hirschberg, pp. 105-106, 209.
Request for proposals The request for proposals (RFP) for demonstration and validation (Dem/Val) was issued in September 1985, with proposals initially to be due that December.Sweetman 1991, p. 14. The top four proposals, later reduced to two to reduce program costs, would proceed with Dem/Val. The RFP not only had the ATF's demanding technical requirements, but also placed great importance on systems engineering, technology development plans, and risk mitigation; in fact, these areas were deemed more important than the aircraft design proposals themselves as contractors would later discover in their debriefs after Dem/Val selection.Mullin 2019, pp. 33-35. This was because the SPO anticipated that the ATF would need to employ emerging technologies beyond even the contemporary state-of-the-art and did not want an aircraft design frozen at then-current mature technology readiness levels; as such, the SPO needed to evaluate its confidence in a contractor's ability to effectively and affordably develop new technology. Initially, there was no requirement for flying prototype air vehicles.
At this time, the SPO had anticipated procuring 750 ATFs at a unit flyaway cost of $35 million in fiscal year (FY) 1985 dollars (~$ in ) with final design selection in 1989 and service entry in 1995 with a peak production rate of 72 aircraft per year; this was essentially a 1-for-1 replacement for the service's air superiority F-15A/B/C/D fleet. Total program cost was expected to be $44.3 billion in FY 1985 dollars (~$ in ), with $26.3 billion (~$ in ) in procurement at flyaway cost. However, even at this point, the peak rate was being questioned and the entry date was at risk of slipping further to the mid/late 1990s due to potential RFP adjustments and budget constraints.
Shortly afterwards, the Navy under Congressional pressure joined the ATF program initially as an observer to examine the possibility of using a navalized derivative of the ATF by adapting the design for carrier operations; named the Navy Advanced Tactical Fighter (NATF), it was to replace the F-14 Tomcat. The Navy would eventually announced in 1988 that they plan to procure 546 aircraft under the NATF program at a peak rate of 48 per year.Miller 2005, p. 14.Aronstein and Hirschberg 1998, pp. 235-239.