c/n 17158 Built in 1954 as a private venture known simply as the Dash-80 and was intended to demonstrate the advantages of jet-powered airliners. She first flew on 15th July 1954, the 34th Anniversary of the founding of the Boeing company and at that time she had cost Boeing $16million but had no confirmed orders. She subsequently became the prototype for the Boeing 707, of course, and Boeing soon made good on their investment with over 1,815 airframes being sold by the time production finished in 1992. That total includes 1,012 of the mainly civilian Boeing 707 (including Boeing 720 and E-3 Sentry), as well 803 of the C-135 military variant, usually in airborne-refuelling configuration as the KC-135 Stratotanker. The Dash-80 flew as a demonstrator and famously carried out two barrel-rolls over Lake Washington on 6th August 1955, while being flown by Boeing test-pilot Alvin ‘Tex’ Johnson. He later claimed he was only ‘selling airplanes’ (which was his job, after all), but was told by Boeing President Bill Allen that it was not to be repeated! After the first production 707s appeared in 1957 the Dash-80 became a test and experimental aircraft, at one time carrying an air-refuelling ‘flying boom’ for the KC-135 programme and later having a tail-mounted fifth engine while testing systems for the Boeing 727. She was finally retired in 1969 after flying 2,350 hours during 1,691 flights. She was flown to Davis-Monthan AFB in Tucson, Arizona, for storage and was displayed as part of ‘celebrity row’ at MASDC / AMARC. In 1972 she was donated to the Smithsonian Institute, who had designated her as one of the 12 most significant aircraft of all time. She remained at Davis-Monthan until 1990, when she was returned to Boeing for restoration. She was flown to Dulles on 27th August 2003 and is seen on display at the Steven F. Udvar Hazy Center as part of the National Air and Space Museum. Washington Dulles International Airport, Chantilly, Virginia