from Johnson, who previously insisted that the D-21 had less RCS than Have Blue. 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). McDonnell Douglas, having identified the thresholds at which aircraft were deemed undetectable, was unable to design and produce such an aircraft. 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. 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. On 1 November 1975, Lockheed and Northrop were each awarded $1.5-million contracts to proceed with Phase 1 of XST. 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 Radar Target Scatter (RATSCAT) test facility at White Sands, New Mexico. 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 because the Northrop XST had a much higher side hemisphere RCS. 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 Tacit Blue and, ultimately, the B-2 bomber. Construction and further tests Skunk Works now had to design, construct and flight test two manned demonstrators as part of Phase 2, or Have Blue. To build the demonstrators, Ben Rich had to raise $10.4 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 radio wave, infrared, and visual spectrums and reduced acoustical observability; acceptable flying qualities; and the "modeling capabilities that accurately predict low observable characteristics of an aircraft in flight". Construction of both Have Blue demonstrators used leftover tools from the C-5 program. Final assembly of HB1001 was originally scheduled to be completed in