Advanced Tactical Fighter

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Advanced Tactical Fighter (ATF)
The YF-22 (foreground) and YF-23 (background)
General information
Project forAir superiority fighter
Issued byUnited States Air Force
Proposalsproposals from Boeing, General Dynamics, Lockheed, Northrop, and McDonnell Douglas[1]
PrototypesLockheed YF-22, Northrop YF-23
RequirementAdvanced Tactical Fighter Statement of Operational Need (November 1984)
History
InitiatedMay 1981 (1981-05) (RFI), September 1985 (1985-09) (RFP)
ConcludedAugust 1991 (1991-08)
OutcomeYF-22 team selected for full-scale development of the F-22 for production and service
VariationsJAFE, NATF, Have Dash II

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.[2] 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.

History[edit]

Concept development[edit]

In 1981, USAF began forming requirements for the ATF and in May, a request for information (RFI) 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 and analyzed by ASD which release their final report in December 1982. During this time, the ASD also established the ATF Concept Development Team in October 1982 to manage concept development studies. While there was a great variety in the responses due to the ATF still early in its requirements definition, including whether the aircraft would be focused on air-to-air or air-to-surface, the common areas among the concepts were stealth, STOL and supercruise.[3] 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.[4]

Diagram of several designs submitted for request for information (RFI).
ATF SPO Patch, 1990

By October 1983, the ATF Concept Development Team had become the System Program Office (SPO) at Wright-Patterson Air Force Base and determined that the ATF should focus on air-to-air; the air-to-surface missions would be handled by the Dual-Role Fighter program (which would result in the F-15E Strike Eagle) as well as the then-classified F-117 Nighthawk, while the air-to-air threat from the new Soviet fighters and AWACS remained. Thus, the ATF would be a new air superiority fighter with outstanding aerodynamic performance intended to replace the capability of the F-15 Eagle. Further 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, 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.[5]

During this time, the SPO took an increasing interest in stealth as results from 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) promised greatly reduced radar signatures that were orders of magnitude smaller than existing aircraft. The ATF requirements would place increasing emphasis on stealth over the course of concept exploration, while still demanding fighter-like speed and maneuverability. By late 1984, the SPO had settled on the ATF requirements and released the Statement of Operational Need (SON), which called for a fighter with a takeoff gross weight of 50,000 pounds (23,000 kg), a mission radius of 800 miles (1,300 km), supercruise speed of Mach 1.4–1.5, the ability to use a 2,000 feet (610 m) runway, and stealth particularly in the frontal sector.[6]

Request for proposals[edit]

A request for proposals (RFP) for demonstration and validation (Dem/Val) was issued in September 1985, with proposals initially to be due that December.[4][7] The top four proposals, later reduced to two, 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 point aircraft designs as contractors would discover in their debrief after selection. This was in part because the SPO was anticipating that the ATF would need to incorporate technologies well beyond even the contemporary state-of-the-art and needed confidence in the contractor's ability to affordably develop them. At this time, the SPO had anticipated procuring 750 ATFs at a unit cost of $35 million in fiscal year (FY) 1985 dollars. Shortly afterwards, the U.S. Navy under Congressional pressure joined the ATF program initially as an observer to examine the possibility using a navalised derivative, named the Navy Advanced Tactical Fighter (NATF), to replace the F-14 Tomcat; the Navy would eventually announced that they would procure 546 aircraft under the NATF program.[8]

The Dem/Val RFP would see some changes after its first release that pushed the due date to July 1986; in December 1985, following discussions with Lockheed and Northrop, the two contractor teams with prior stealth experience from the F-117 and B-2 respectively, stealth requirements were drastically increased. Furthermore, the Packard Commission had released its report in 1986, and one of its recommendations was a "fly-before-buy" competitive procurement strategy that encouraged prototyping. The ATF SPO was pressured to followed the recommendations of the Packard Commission, and in May 1986, the Air Force changed the RFP so that final selection would involve flying prototypes.[9]

In July 1986, proposals were provided by Boeing, General Dynamics, Grumman, Lockheed, Northrop, McDonnell Douglas, and Rockwell; Grumman and Rockwell would drop out shortly afterwards.[1] Because contractors were expected to make immense investments of their own, likely matching or exceeding the amounted awarded by the contracts themselves, in order to develop the necessary technology to meet the ambitious requirements, teaming was encouraged by the SPO. Following proposal submissions, Lockheed, Boeing, and General Dynamics formed a team to develop whichever of their proposed designs was selected, if any. Northrop and McDonnell Douglas formed a team with a similar agreement.[10]

Two contractors, Lockheed and Northrop, were selected on 31 October 1986 as first and second place and would proceed as the finalists. Noteworthy is the divergent approach of the two finalists' proposals. Northrop's proposal leveraged its considerable experience with stealth to produce a refined and well-understood aircraft design that was very similar to the eventual flying prototype. While Lockheed also had extensive prior stealth experience, their actual aircraft design was quite immature and only existed as a rough concept; instead, Lockheed primarily focused on systems engineering and trade studies in its proposal, which pull it ahead of Northrop's to take top rank. The two teams, Lockheed/Boeing/General Dynamics and Northrop/McDonnell Douglas, then undertook a 50-month Dem/Val phase, culminating in the flight test of two technology demonstrator prototypes, the YF-22 and the YF-23.[11]

Demonstration and validation[edit]

The Dem/Val phase was intended to develop and mature ATF technology for the fighter's eventual production and was focused on three main activities, system specification development, avionics ground prototypes and flying laboratories, and prototype air vehicles.[12]

Unlike many prior USAF programs, the ATF SPO had set the technical requirements without specifying the "how", thus giving the contractor teams the flexibility to develop the necessary technology and offer competing methods. Furthermore, the SPO was also open to adjusting those requirements if necessary. Both contractor teams conducted performance and cost trade studies and presented them in system requirement reviews (SRRs) with the SPO. This enabled the SPO to adjust ATF requirements and delete ones that were significant weight and cost drivers while having marginal operational value. For instance, the number of missiles (represented by the AIM-120A) carried was reduced from eight to six to reduce weight and cost. 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 3,000 feet (910 m) and removed the thrust reversers on the ATF in late 1987.[13][14] 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 50,000 lb (22,700 kg) to 60,000 lb (27,200 kg), resulting in engine thrust requirement increasing from 30,000 lbf (133 kN) to 35,000 lbf (156 kN) class.[15]

Aside from advances in air vehicle and propulsion technology, the ATF would make a leap in avionics performance with a fully integrated avionics suite that would fuse sensor information together into a common tactical picture, thus improving the pilot's situational awareness and reducing workload. As such, the Dem/Val phase for avionics development focused on the demonstration of the hardware and software with avionics ground prototypes (AGP) for performance and reliability. Although not required, both teams would employ flying avionics laboratories as well, with the Lockheed team using a modified Boeing 757 as a Flying Test Bed and the Northrop team using a modified BAC One-Eleven.[16] The avionics requirements were also the subject of SRRs and adjustments; 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. In 1989, a $9 million per aircraft cost cap on avionics in FY 1985 dollars was imposed by the SPO to contain requirements creep.

Lockheed team's YF-22 and Northrop team's YF-23 flying in formation

Finally, two examples of each prototype were built and flown for Dem/Val: one with General Electric YF120 engines, the other with Pratt & Whitney YF119 engines.[4][17] The first YF-23 made its maiden flight on 27 August 1990 and the first YF-22 first flew on 29 September 1990.[18] Flight testing began afterwards and added the second aircraft for each competitor in late October 1990.[19] The first YF-23 with P&W engines supercruised at Mach 1.43 on 18 September 1990 and the second YF-23 with GE engines reached Mach 1.72 on 29 November 1990.[19][20] The YF-22 with GE engines achieved Mach 1.58 in supercruise.[21] Flight testing continued until December 1990. Following flight testing, the contractor teams submitted proposals for ATF production.[19]

Selection and full-scale development[edit]

The production F-22 Raptor.

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.[22] Both designs met or exceeded all performance requirements; the YF-23 was stealthier and faster, but the YF-22 was more agile.[23] The US Navy had begun considering a version of the ATF called Navy Advanced Tactical Fighter (NATF) in 1986.[24] It has been speculated in the aviation press that the YF-22 was also seen as more adaptable to the NATF.[25] However, by late 1990 to early 1991, the Navy was beginning to back out of NATF due to escalating costs, and abandoned NATF completely by FY 1992.[26]

The Lockheed team was awarded the EMD contract to develop and build the Advanced Tactical Fighter in August 1991. The YF-22 design was evolved to become the EMD/production F-22 Raptor version, which first flew in September 1997.[27] The Northrop YF-23 design was later considered by the company for modification as a bomber,[22] but the proposals have not come to fruition.[28] Following flight and operational testing, the F-22 entered service in December 2005, but with the collapse of the Soviet Union and the Department of Defense focused on counterinsurgency at that time, F-22 production only reached 195 aircraft and ended in 2011.[29][30]

See also[edit]

Notes[edit]

References[edit]

Citations[edit]

  1. ^ a b Miller 2005, pp. 14, 19.
  2. ^ Sweetman 1991, p. 10-11, 21.
  3. ^ Sweetman 1991, pp. 12–13.
  4. ^ a b c YF-22 fact sheet Archived January 19, 2012, at the Wayback Machine. National Museum.
  5. ^ Sweetman 1991, p. 13.
  6. ^ Miller 2005, p. 13.
  7. ^ Sweetman 1991, p. 14.
  8. ^ Miller 2005, p. 14.
  9. ^ Aronstein and Hirschberg 1998, pp. 82-89
  10. ^ Goodall 1992, p. 94
  11. ^ Miller 2005, pp. 19–20.
  12. ^ Aronstein and Hirschberg 1998, p. 104
  13. ^ Sweetman 1991, p. 23.
  14. ^ Miller 2005, p. 23.
  15. ^ Aronstein and Hirschberg 1998, pp. 105–108.
  16. ^ Aronstein and Hirschberg 1998, pp. 113-115
  17. ^ YF-23 fact sheet Archived July 16, 2011, at the Wayback Machine. National Museum.
  18. ^ Goodall 1992, p. 99.
  19. ^ a b c Miller 2005, pp. 38–39.
  20. ^ Paul Metz, Jim Sandberg (27 August 2015). YF-23 DEM/VAL Presentation by Test Pilots Paul Metz and Jim Sandberg. Western Museum of Flight: Peninsula Seniors Production.
  21. ^ Goodall 1992, pp. 102–103.
  22. ^ a b Miller 2005, p. 38.
  23. ^ Goodall 1992, p. 110.
  24. ^ Pace 1999, pp. 19–22.
  25. ^ The Lockheed Martin F/A-22 Raptor Archived January 6, 2009, at the Wayback Machine. Vectorsite.net, 1 February 2007.
  26. ^ Miller 2005, p. 76.
  27. ^ Miller 2005, pp. 38, 42–46.
  28. ^ Hebert, Adam J. "The 2018 Bomber and Its Friends". Air Force magazine, October 2006.
  29. ^ "F-22A Raptor goes operational". U.S. Air Force. 15 December 2005. Archived from the original on 23 July 2012. Retrieved 24 June 2011.
  30. ^ Parsons, Gary. "Final F-22 Delivered" Archived 13 March 2016 at the Wayback Machine Combat Aircraft Monthly, 3 May 2012. Retrieved 10 April 2014.

Bibliography[edit]

  • Goodall, James C. "The Lockheed YF-22 and Northrop YF-23 Advanced Tactical Fighters". America's Stealth Fighters and Bombers, B-2, F-117, YF-22, and YF-23. St. Paul, Minnesota: MBI Publishing Company, 1992. ISBN 0-87938-609-6.
  • Hehs, Eric (16 October 1998). "Design Evolution of the F-22, Part 1 and 2". Code One. Lockheed Martin.
  • Jenkins, Dennis R. and Tony R. Landis. Experimental & Prototype U.S. Air Force Jet Fighters. North Branch, Minnesota: Specialty Press, 2008. ISBN 978-1-58007-111-6.
  • Metz, Alfred "Paul". Air Force Legends Number 220. Northrop YF-23 ATF. Forrest Lake, Minnesota: Specialty Press, 2017 ISBN 0989258378
  • Miller, Jay. Lockheed Martin F/A-22 Raptor, Stealth Fighter. Hinckley, UK: Midland Publishing, 2005. ISBN 1-85780-158-X.
  • Miller, Jay (1995). Lockheed Martin's Skunk Works: The Official History... Leicester, UK: Midland Publishing. ISBN 1-85780-037-0.
  • Mullin, Sherman N. (June 2012). "Winning the ATF" (PDF). Mitchell Institute for Airpower Studies.
  • Pace, Steve. F-22 Raptor. New York: McGraw-Hill, 1999. ISBN 0-07-134271-0.
  • Sweetman, Bill. YF-22 and YF-23 Advanced Tactical Fighters. St. Paul, Minnesota: Motorbooks International Publishing, 1991. ISBN 0-87938-505-7.
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