Editing Lockheed Have Blue (section)

==Design and development==
=== Origins ===
The Lockheed ''Have Blue'' was born out of a requirement to evade radar detection. During the [[Vietnam War]], radar-guided SAMs and AAA posed a significant threat to US aircraft. For this reason, strike aircraft during the war often required support aircraft to perform combat air patrols and [[suppression of enemy air defenses]] (SEAD).<ref name=Crickmore_p9>Crickmore 2003, p.&nbsp;9.</ref> The 1973 [[Yom Kippur War]] again highlighted the vulnerability of aircraft to SAMs – the [[Israeli Air Force]] lost 109 aircraft in 18 days.<ref name=Crickmore_p9/> During the [[Cold War]], the [[Soviet Union]] developed an integrated defense network, central to which were medium- to long-range surveillance radars. SAMs and AAAs would be set up around key locations to defend them from incoming enemy aircraft.<ref name=Crickmore_p9/> If the loss ratio of Israel during the Yom Kippur War was experienced by NATO forces during a military confrontation with the [[Warsaw Pact]], NATO aircraft numbers would be depleted within two weeks.<ref name=Crickmore_p9/>

In 1974, DARPA secretly requested answers from five aircraft manufacturers regarding two considerations. The first was about the signature thresholds at which an aircraft is virtually undetectable. The second point was whether these companies had the capability to design and manufacture such an aircraft.<ref name=Crickmore_p9/> [[Fairchild Aircraft|Fairchild]] and [[Grumman]] declined to participate, while [[General Dynamics]] insisted on the use of [[electronic countermeasures]]. As a result, General Dynamics left the discussion. The remaining two companies, [[McDonnell Douglas]] and [[Northrop Corporation|Northrop]], were each awarded $100,000 for further research.<ref>Jenkins 1999, p.&nbsp;15.</ref>

=== Design effort and early testing ===
Lockheed, having been absent from the fighter aircraft industry for 10 years, was not approached by DARPA in 1974. Ed Martin, Lockheed California Companies director of science and engineering, became aware of the research into stealth during his work at [[the Pentagon]] and [[Wright-Patterson AFB]].<ref name=Crickmore_p10>Crickmore 2003, p.&nbsp;10.</ref> Martin and [[Ben Rich (engineer)|Ben Rich]], who at that time had recently become [[Skunk Works]]' president, briefed [[Kelly Johnson (engineer)|Clarence "Kelly" Johnson]] on the program. The [[Central Intelligence Agency]] (CIA) gave Skunk Works permission to discuss with DARPA the stealth characteristics of the [[Lockheed A-12|A-12, M-21 and D-21]].<ref name=Crickmore_p10 /> On behalf of the company, Rich and Martin formally requested permission from DARPA to participate in the program, but the agency initially refused because there were insufficient funds; after much debate, Lockheed was allowed entry, albeit without a government contract.<ref name=Crickmore_p10 />
[[File:ClarenceLeonardKellyJohnson.jpg|thumb|[[Kelly Johnson (engineer)|Kelly Johnson]], Lockheed's designer, was initially skeptical of the ''Have Blue'' project]]

Preliminary designer [[Richard C. Scherrer|Dick Scherrer]] requested possible shapes upon which he could base his low [[radar cross-section]] (RCS) design. He was introduced to Denys Overholser,<ref>{{cite web|author=Capi Lynn|date=16 April 2016 |title=Secret weapon for stealth tech is from Dallas |url=https://www.statesmanjournal.com/story/news/2016/04/16/secret-weapon-stealth-tech-dallas/82678480/|access-date=2016-04-19 |website=Statesman Journal}}</ref> who recommended an aircraft with flat surfaces. Overholser later recounted his discussion with Sherrer: "When Dick Scherrer asked me ... I said 'Well, it's simple, you just make it out of flat surfaces, and tilt those flat surfaces over, sweeping the edges away from the radar view angle, and that way you basically cause the energy to reflect away from the radar.'"<ref name=Crickmore_p11>Crickmore 2003, p.&nbsp;11.</ref> Scherrer subsequently drew a preliminary low-RCS aircraft with faceted surfaces.<ref name=Crickmore_p11 /> At the same time, Overholser hired mathematician Bill Schroeder, with whom he had a prior working relationship – in fact, it was Schroeder who trained Overholser on mathematics relating to stealth aircraft.<ref name=Crickmore_p11 /> Kenneth Watson was hired as the senior lead aircraft designer.<ref name=Crickmore_p11 />

During the next few weeks, the team created a computer program which could evaluate the RCS of possible designs. The RCS-prediction software was called "ECHO 1". As tests with the program proceeded, it became apparent that edge calculations by the program were incorrect due to [[diffraction]].<ref name=Crickmore_p11 /> To overcome this, Overholser incorporated elements of research by Soviet engineer [[Pyotr Ufimtsev]] into the software.<ref name=Crickmore_p11 /><ref>Jenkins 1999, p.&nbsp;16.</ref> (In 1962, Ufimtsev, as chief scientist of the Moscow Institute for Radio Engineering, published a seminal paper titled ''Method of Edge Waves in the Physical Theory of Diffraction''. The work had been translated by the US [[Air Force Systems Command]]'s Foreign Technology Division.<ref>Ufimtsev 1962.</ref>)
ECHO 1 allowed the team to quickly decide which of the 20 possible designs were optimal, finally settling on the faceted delta-wing design.<ref name=Crickmore_p12>Crickmore 2003, p.&nbsp;12.</ref> However, many within the division were skeptical of the shape, giving rise to the name "Hopeless Diamond"<ref name=Sweetman_p25>Sweetman 2005, p.&nbsp;25.</ref>&nbsp;– Kelly Johnson said to Rich, "Our old [[Lockheed D-21|D-21]] drone has a lower radar cross-section than that goddamn diamond".<ref name=Crickmore_p12 />

In May 1975, the Skunk Works produced an internal report titled, "Progress Report No. 2, High Stealth Conceptual Studies." Within it was a concept study called "Little Harvey," including Kelly Johnson's drawing of an aircraft with smoothly blended shapes. Johnson advocated for the use of blended shapes as the best way to achieve stealth, while Ben Rich advocated for faceted angles. Rich won the argument with Johnson, a rare occurrence.<ref>Slattery, Chad, "Secrets of the Skunk Works," ''Air & Space'', August 2014, p. 41</ref>

The design effort produced a number of wooden models. A 24-inch long model, made of [[balsa wood]], demonstrated placement of internal structure and access doors. An ''Air & Space'' article noted "The model shop found it nearly impossible to make all the flat surfaces come to a single point in one corner. Engineers later encountered the same difficulty fabricating the prototype on the factory floor."<ref>Slattery 2014, p. 43</ref> For early tests of the design, two ⅓-scale wooden mock-ups were constructed. One model, coated in metal foil, was used to verify ECHO 1's RCS calculations, while the other was earmarked for wind tunnel tests.<ref name=Crickmore_p12 /><ref name=HB_FTP>{{cite web|title=Have Blue Flight Test Program|website=GlobalSecurity.org |url=http://www.globalsecurity.org/military/systems/aircraft/have-blue-flight.htm|access-date=31 July 2011}}</ref> Afterwards, a model was moved to the [[Grey Butte Range]] radar-testing facility in the [[Mojave Desert]] near [[Palmdale]], which allowed more accurate tests of the aircraft's RCS. In the event, the aircraft's RCS level confirmed ECHO 1's predictions.<ref name=Crickmore_p12 /> This meant Ben Rich won a [[Quarter (United States coin)|quarter]] from Johnson, who previously insisted that the D-21 had less RCS than ''Have Blue''.<ref name=Crickmore_p12 />

=== Experimental Survivable Testbed ===
In the summer of 1975, DARPA informally invited Lockheed, Northrop and McDonnell Douglas to develop an aircraft under the name "Experimental Survivable Testbed" (XST).<ref name=Sweetman_p25/><ref name=Jenkins_p17>Jenkins 1999, p.&nbsp;17.</ref> McDonnell Douglas, having identified the thresholds at which aircraft were deemed undetectable, was unable to design and produce such an aircraft.<ref name=Crickmore_p13>Crickmore 2003, p.&nbsp;13.</ref> Phase 1 of XST would see both Lockheed and Northrop build full-scale models to test their RCS, construct flyable vehicles, and wind-tunnel test their designs. Following Phase 1, a sole contractor would be selected to continue with the construction and flight testing of two demonstrators as part of Phase 2.<ref name=Jenkins_p17/> Northrop's and Lockheed's designs were generally similar, though the former's submission featured more angular and flat surfaces. The company used "GENSCAT", software similar to ECHO 1, to calculate the RCS of its designs.<ref name=Crickmore_p13/><ref>Jenkins 1999, p.&nbsp;18.</ref>

On 1 November 1975, Lockheed and Northrop were each awarded $1.5-million contracts to proceed with Phase 1 of XST.<ref>Aronstein and Piccirillo 1997, p.&nbsp;29.</ref> During a four-month period, the two companies were each required to construct full-scale wooden mock-ups, which would then be evaluated at the USAF's [[National Radar Cross-section Facility|Radar Target Scatter]] (RATSCAT) test facility at [[White Sands, New Mexico]].<ref name=Crickmore_p13/> To test the design's radar returns, Lockheed erected a $187,000 specially built pole upon which the model would be perched. In March 1976, a Lockheed model was transferred to the range before being tested; the following month Lockheed was pronounced the winner<ref>Aronstein and Piccirillo 1997, pp.&nbsp;32–33.</ref> because the Northrop XST had a much higher side hemisphere RCS.{{clarify|lower or higher? lower-better ; higher-worse|date=December 2019}}<ref>Sweetman 1999, p.&nbsp;13.</ref> DARPA, having realized the progress accumulated throughout the study, urged the Northrop team to remain together. The agency would later initiate the [[Battlefield Surveillance Aircraft-Experimental]] (BSAX), which evolved into the [[Northrop Tacit Blue|Tacit Blue]] and, ultimately, the [[Northrop Grumman B-2 Spirit|B-2]] bomber.<ref name=A&P_p33>Aronstein and Piccirillo 1997, p.&nbsp;33.</ref>

=== Construction and further tests ===
[[File:Lockheed Have Blue art.jpg|thumb|right|Lockheed Have Blue concept art]]
Skunk Works now had to design, construct and flight test two crewed demonstrators as part of Phase 2, or ''Have Blue''. To build the demonstrators, Ben Rich had to raise $10.4&nbsp;million from the Lockheed management, which was secured by June. Phase 2 encompassed three main objectives, which were the validation of: reduced visibility in the [[Radar cross-section|radio wave]], [[Infrared signature|infrared]], and [[Aircraft camouflage|visual]] spectrums and reduced [[Acoustic signature|acoustical]] observability; acceptable flying qualities; and the "modeling capabilities that accurately predict low observable characteristics of an aircraft in flight".<ref name=A&P_p33/>

Construction of both ''Have Blue'' demonstrators used leftover tools from the [[Lockheed C-5 Galaxy|C-5]] program. Final assembly of HB1001 was originally scheduled to be completed in August 1977, before being ground tested until mid-October. The secret roll-out was envisaged to occur on 23 October, after which the aircraft would be dismantled and transported to the test area.<ref name=Crickmore_p16>Crickmore 2003, p.&nbsp;16.</ref> On 1 September, however, with HB1001 partially complete, Lockheed machinists went on a four-month strike. A group of managers took over the job of assembly, which was completed in six weeks, with ground tests beginning on 17 October.<ref name=Crickmore_p17>Crickmore 2003, p.&nbsp;17.</ref>

While superficially similar to the later F-117, the ''Have Blue'' prototypes were smaller aircraft, about one quarter the weight of the F-117, with a [[Swept wing|wing sweep]] of 72.5° and inward-canted vertical tails (inverse [[V-tail]]).<ref name=Eden_p243>Eden 2004, p.&nbsp;243.</ref><ref>Aronstein, Hirschberg and Piccirillo 1998, p.&nbsp;261.</ref> [[Radar-absorbent material]] (RAM), developed in a Lockheed laboratory, was applied to the aircraft's flat surfaces – for the windscreen, special coatings were applied to give them metallic characteristics.<ref>Donald 2003, p.&nbsp;67.</ref><ref name=Eden_p242>Eden 2004, p.&nbsp;242.</ref> The aircraft's gross weight of 9,200–12,500&nbsp;lb (4,173–5,669&nbsp;kg) enabled the aircraft to use the landing gear from the [[Northrop F-5]] fighter.<ref name=Eden_p242/> The aircraft's [[Aircraft engine|powerplant]]s were two {{Convert|2950|lbf|kN|adj=on}} [[General Electric J85]]-GE-4As from the [[T-2C Buckeye]].<ref name=AHP_p263/><ref>Sweetman 2005, p&nbsp;30.</ref> Because stealth took precedence above all else, the aircraft was inherently [[Relaxed static stability|unstable]]. As a result, a quadruple redundant [[fly-by-wire]] (FBW) flight control system was integrated into the aircraft to give it normal flying characteristics. The flight control system was borrowed from the [[General Dynamics F-16 Fighting Falcon|F-16]].<ref name=AHP_p263>Aronstein, Hirschberg and Piccirillo 1998, p.&nbsp;263.</ref> The overwing engine inlet was covered by a low-RCS grid; blow-in doors were constructed at the upper fuselage to admit additional airflow during takeoffs, when more air is needed.<ref>Crickmore 2003, pp.&nbsp;15–16.</ref>

Throughout the one and a half months after the start of ground tests, HB1001, the first of two demonstrators, underwent tests in preparations for the first flight. Flight instrumentation was checked first, followed by a thorough [[Shakedown (testing)|shakedown]] of the aircraft. In early November, two [[semi-trailer]]s were parked parallel to each other outside Building 82; a camouflage net was thrown over the top to cover the demonstrator during outdoor engine runs. During the engine tests, a local resident complained about the noise, but ''Have Blue'' retained its secrecy.<ref name=Crickmore_p17/> HB1001 received a layer of iron-coat paint; during the weekend of 12–13 November, the aircraft received a camouflage scheme devised by Alan Brown, ''Have Blue''{{'}}s chief technical engineer. The scheme, consisting of three colors, each with three tones, was used to deceive any casual onlooker from recognizing the design's characteristic [[faceting]].<ref name=Crickmore_p17/> The aircraft was disassembled, loaded onto a C-5, and on 16 November, the aircraft was flown from [[Bob Hope Airport|Burbank Airport]] (since renamed ''Bob Hope Airport'') to [[Area 51]] at [[Groom Lake]], [[Nevada]]. Upon touchdown, the aircraft was reassembled before undergoing another round of testing prior to the first flight.<ref>Crickmore 2003, pp.&nbsp;17–18.</ref> After four taxi tests, HB1001 was ready for test flights.<ref name=Crickmore_p19>Crickmore 2003, p.&nbsp;19.</ref>