Editing Lockheed YF-22 (section)

===Demonstration and validation===
[[File:Lockheed Faceted ATF.jpg|thumb|left|Early Lockheed ATF concept with faceted shape for stealth]]
By November 1984, the SPO had further narrowed the requirements and released the Statement of Operational Need (SON), with requirements calling for a {{convert|50000|lb|kg|-2|abbr=on}} takeoff weight fighter that places strong emphasis on stealth, maneuver, and supersonic cruise without afterburners, or [[supercruise]]; [[radius of action|mission radius]] was expected to be {{convert|500|nmi|mi km|sigfig=2}} mixed subsonic/supersonic or {{convert|700|-|800|nmi|mi km|sigfig=3}} subsonic.<ref name="SON_RFP">Aronstein and Hirschberg 1998, pp. 70–78.</ref> In September 1985, the Air Force sent out technical [[request for proposal]]s (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 of $35&nbsp;million in [[fiscal year]] (FY) 1985 dollars (~${{Format price|{{Inflation|index=US-GDP|value=35000000|start_year=1985}}}} in {{Inflation/year|US-GDP}}).<ref name="Hehs1998P1"/><ref name="SON_RFP"/><ref>Aronstein and Hirschberg 1998, pp. 87–88.</ref> 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 [[Grumman F-14 Tomcat|F-14 Tomcat]] as the Navy Advanced Tactical Fighter (NATF); the service called for the procurement of 546 aircraft.<ref name=Williams_p5>Williams 2002, p. 5.</ref>

[[File:Lockheed Model 090P 300x172.jpg|thumb|Lockheed's submission for Dem/Val RFP, designated Configuration 090P]]
Having performed poorly during ATF concept exploration while also [[Lockheed Senior Peg|losing the ATB]] to [[Northrop Corporation|Northrop]] who had a curved surface design, Lockheed 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 [[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,{{refn|A stealthy curved radome was the last challenge Lockheed overcame in early 1985.<ref name="Hehs1998P1"/>|group=N}} the final design submitted for Dem/Val, designated Configuration 090P, would have an arrowhead-like forward fuselage shape, swept [[trapezoidal wing]]s, four [[empennage]] tail surfaces, [[S-duct|S-shaped]] inlet ducts obscuring the engine face, and an internal rotary missile launcher.<ref name="Hehs1998P1"/> 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 team|red-teamed]] by a group led by retired Air Force general [[Alton D. Slay]].<ref>Mullin 2012, p. 13.</ref> The resulting proposal improvements were substantial, particularly the systems engineering volume.<ref>Mullin 2012, pp. 18–19.</ref>

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, and 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.<ref>Aronstein and Hirschberg 1998, pp. 82–85.</ref><ref>Mullin 2012, pp. 19–21.</ref> Seven companies submitted bids in July&nbsp;1986.{{refn|The seven bidding companies were Lockheed, Boeing, General Dynamics, McDonnell Douglas, Northrop, [[Grumman]], and [[Rockwell International|North American Rockwell]].<ref>Miller 2005, pp. 14, 19.</ref>|group=N}} 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.<ref>Goodall 1992, p. 94.</ref>

On [[Halloween|31&nbsp;October&nbsp;]]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 $691&nbsp;million contracts in FY 1985 dollars (~${{Format price|{{Inflation|index=US-GDP|value=691000000|start_year=1985}}}} in {{Inflation/year|US-GDP}}) and would undertake a 50-month demonstration and validation phase, culminating in the flight test of the two teams' prototypes, the YF-22 and the [[Northrop YF-23|YF-23]]; [[Pratt & Whitney]] and [[General Electric]] had earlier been awarded contracts to develop the competing prototype propulsion systems with the designations [[Pratt & Whitney F119|YF119]] and [[General Electric YF120|YF120]] respectively.<ref name=Miller_p19-0>Miller 2005, pp.&nbsp;19–20.</ref><ref>Jenkins and Landis 2008, pp.&nbsp;233–234.</ref><ref name="Williams 2002, pp. 5–6">Williams 2002, pp.&nbsp;5–6.</ref> 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.{{refn|The contractor teams were to give the SPO "sealed envelope" flight performance predictions against which their prototypes would be evaluated, rather than against each other.<ref>Aronstein and Hirschberg 1998, p. 137.</ref>|group=N}}<ref>Aronstein and Hirschberg 1998, pp. 87–88.</ref>