Editing Lockheed Have Blue (section)

=== 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>