The Lockheed–Boeing–General Dynamics YF-22 is an American single-seat, twin-engine, stealth fighter prototype technology demonstrator designed for the United States Air Force (USAF). The design team, with Lockheed as the prime contractor, was a finalist in the USAF's Advanced Tactical Fighter (ATF) competition, and two prototypes were built for the demonstration and validation phase. The YF-22 team won the contest against the Northrop-led YF-23 team for full-scale development and the design was developed into the Lockheed Martin F-22.Lockheed merged with Martin Marietta in 1995 to form Lockheed Martin. The YF-22 has a similar aerodynamic layout and configuration as the F-22, but with notable differences in the overall shaping such as the position and design of the cockpit, tail fins and wings, and in internal structural layout.
In the 1980s, the USAF began looking for a replacement for its fighter aircraft to counter emerging threats such as the advanced Soviet Su-27 and MiG-29. A number of companies submitted their proposals, with the competition narrowing down to Lockheed and Northrop as the two finalists for demonstration/validation. Northrop teamed with McDonnell Douglas to develop the YF-23; Lockheed teamed with Boeing and General Dynamics to develop the YF-22, which, although marginally slower and having a larger radar cross-section, was more agile than the YF-23. The Lockheed team was picked by the Air Force as the winner of the ATF competition in April 1991. The U.S. Navy considered adopting a naval version of the ATF, but these plans were later canceled due to cost.
Following the selection, the first prototype was retired as an exhibit at the Air Force Flight Test Museum, while the second continued flight testing until an accident relegated it to the role of an antenna test vehicle and it was later stored.
Development
Concept definition In 1981, the U.S. Air Force (USAF) began exploring concepts and developing requirements for an Advanced Tactical Fighter (ATF) that would eventually become a new air superiority fighter to replace the F-15 Eagle and F-16 Fighting Falcon. This was made more crucial by the emerging worldwide threats in the late Cold War, including development and proliferation of Soviet MiG-29 "Fulcrum" and Su-27 "Flanker"-class fighter aircraft, A-50 "Mainstay" airborne warning and control system (AWACS), and more advanced surface-to-air missile systems. The ATF would take advantage of the new technologies in fighter design on the horizon including composite materials, lightweight alloys, advanced avionics and flight-control systems, more powerful propulsion systems and stealth technology.
The USAF sent out the ATF request for information (RFI) to the aerospace industry in May 1981 to explore what the future fighter aircraft could look like, and subsequently established a Concept Development Team (CDT) to analyze the results.Aronstein and Hirschberg 1998, p. 30. Eventually code-named "Senior Sky", the ATF at this time was still in the midst of requirements definition with both air-to-air and air-to-ground missions in consideration, and consequently there was substantial variety in the responses from the industry. Lockheed's initial concept was a particularly large aircraft called CL-2016, weighing over at takeoff and nicknamed "battlecruiser" for its size, that resembled its SR-71/YF-12 with large delta wings and engines mounted in nacelles spaced away from the fuselage and would have had similarly high operating speed and altitude as a missile platform (or "missileer" per Lockheed).Hehs 1998, Part 1.Aronstein and Hirschberg 1998, pp. 39–42.
In 1983, the ATF Concept Development Team became the System Program Office (SPO) at Wright-Patterson Air Force Base. After discussions with aerospace companies and Tactical Air Command (TAC), the CDT/SPO narrowed the requirements to an air superiority fighter with outstanding kinematic performance, i.e. excellent speed and maneuverability, to replace the F-15.Sweetman 1991, pp. 10–13. Additionally, the SPO began to increasingly emphasize stealth for survivability, while still requiring fighter-like speed and maneuverability, due to the Air Force's experience from "black world" projects such as the Have Blue/F-117 ("Senior Trend") and the Advanced Technology Bomber (ATB) program (which would result in the B-2, or "Senior Ice").Aronstein and Hirschberg 1998, pp. 45–58. With stealth becoming a core requirement, Lockheed's design team, led by Bart Osborne from its Skunk Works division at Burbank, California, migrated away from its initial SR-71-like "battlecruiser" concept and instead began drafting a design that resembled the company's F-117 stealth attack aircraft. However, the faceted shape, resulting from Lockheed using the same "Echo" computer program that it had used to design the F-117, gave the design very poor aerodynamic performance that would be unsuitable for a fighter. Lockheed would perform poorly throughout the concept exploration phase, placing among the bottom of the competing contractors.
Demonstration and validation
By November 1984, the SPO had further narrowed the requirements and released the Statement of Operational Need (SON), with requirements calling for a takeoff weight fighter that places strong emphasis on stealth, maneuverability, and supersonic cruise without afterburners, or supercruise; mission radius was expected to be mixed subsonic/supersonic or subsonic.Aronstein and Hirschberg 1998, pp. 70–78. In September 1985, the Air Force sent out technical request for proposals (RFP) to a number of aircraft manufacturing teams for demonstration and validation (Dem/Val). In addition to the ATF's demanding technical requirements, Dem/Val also placed a great deal of importance on systems engineering, technology development plans, and risk mitigation. The top four proposals, later reduced to two to reduce program costs, would proceed with Dem/Val as finalists; there was initially no requirement for prototype air vehicles. At the time, the Air Force anticipated procuring 750 ATFs at a unit flyaway cost (or the unit production cost for delivery) of $35 million in fiscal year (FY) 1985 dollars (~$ in ).Aronstein and Hirschberg 1998, pp. 87–88. Furthermore, under Congressional pressure to combine efforts with the Air Force to reduce costs, the U.S. Navy joined the ATF program initially as an observer and eventually announced in 1988 that it would use a variant/derivative of the winning design to replace its F-14 Tomcat as the Navy Advanced Tactical Fighter (NATF); the service called for the procurement of 546 aircraft.Williams 2002, p. 5.
With Lockheed performing poorly during ATF concept exploration with its faceted designs, while also losing the ATB to Northrop's curved surface design, the company abandoned faceting in 1984 and began incorporating curved shapes and surfaces. Although its analytical tools were initially not able to calculate for such shapes, good empirical results from radar range testing at its test range in Helendale, California gave Lockheed confidence in designing a stealthy aircraft with smooth, curved surfaces, thus greatly improving its aerodynamic characteristics. As Lockheed gradually became able to analyze curved shapes, the final design submitted for Dem/Val, designated Configuration 090P, would have an arrowhead-like forward fuselage shape, swept trapezoidal wings, four empennage tail surfaces, S-shaped inlet ducts obscuring the engine face, and an internal rotary missile launcher. In addition to the change in aircraft design, Lockheed also shifted much more engineering talent and manpower to its ATF effort, appointing Sherman Mullin as the program manager, and had its draft proposals aggressively red-teamed by a group led by retired Air Force general Alton D. Slay.Mullin 2012, p. 13. The resulting proposal improvements were substantial, particularly the volume for systems engineering.Mullin 2012, pp. 18–19.
The ATF RFP would see some alterations after its first release. The SPO drastically increased all-aspect stealth requirements in December 1985 after discussions with Lockheed and Northrop regarding their experiences with the Have Blue/F-117 and ATB/B-2. The requirement for flying technology demonstrator prototypes was added in May 1986 due to recommendations from the Packard Commission, a federal commission by President Ronald Reagan to study Department of Defense procurement practices.Aronstein and Hirschberg 1998, pp. 82–85.Mullin 2012, pp. 19–21. Seven companies submitted bids in July 1986. Owing to the immense investments companies were expected to make on their own, 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.Goodall 1992, p. 94.
On 31 October 1986, Lockheed and Northrop, the two industry leaders in stealth aircraft, were selected as the first and second place respectively; Sherman Mullin would credit the Lockheed's top rank to their proposal's system engineering volume, an area other contractors had not emphasized. The two teams, Lockheed/Boeing/General Dynamics and Northrop/McDonnell Douglas, were awarded $691 million contracts in FY 1985 dollars (~$ in ) and would undertake a 50-month demonstration and validation phase, culminating in the flight test of the two teams' prototypes. The SPO designated the YF-22 for Lockheed's aircraft and the YF-23 for Northrop's; Pratt & Whitney and General Electric had earlier been awarded contracts to develop the competing prototype propulsion systems with the designations YF119 and YF120 respectively.Miller 2005, pp. 19–20.Jenkins and Landis 2008, pp. 233–234.Williams 2002, pp. 5–6. Because the requirement for flying prototypes was a late addition due to political pressure, the prototypes were to be "best-effort" vehicles not meant to perform a competitive flyoff or represent a production aircraft, but to demonstrate the viability of its concept and to mitigate risk.
Design evolution
Work would be divided roughly equally across the team. Because Lockheed's submission was selected as one of the winners, the company assumed leadership of the program partners. It would be responsible for the forward fuselage, cockpit, and stealthy edge treatments at Burbank as well as final assembly at Palmdale, California. Meanwhile, the wings and aft fuselage would be built by Boeing at Seattle, Washington, and the center fuselage, weapons bays, tail and landing gear would be built by General Dynamics at Fort Worth, Texas. The team would also invest $675 million (~$ in ) combined into their ATF effort during Dem/Val in addition to the government contract awards.Aronstein and Hirschberg 1998, p. 164. The partners brought their design experience and proposals with them. Boeing's design was large and long with a chin-mounted inlet, trapezoid wings, V-tail empennage surfaces (deemed sufficient due to the high operating speed generating enough dynamic pressure to not require additional control surfaces), and internal weapons bay with ordnance palletized for faster loading. General Dynamics' design was smaller with fuselage and delta wings optimized for maneuver and supercruise, shoulder-mounted inlets, a large single vertical tail as the only empennage surface, and weapon bays in the center fuselage; the single vertical tail surface was an aerodynamic compromise that detracted from the design's all-aspect stealth. However, much of the team's scrutiny fell on Lockheed's Configuration 090P, which was problematic and highly immature as a result of Lockheed's greater focus on systems engineering (i.e. specifications development and trade studies) rather than a detailed point design. Nevertheless, 090P was the initial starting point that the team worked to refine.Hehs 1998, Part 2.