he Boeing Model 367-80 prototype, N70700, was rolled out at the Boeing plant at Renton Field, south of Seattle, Washington. Boeing’s founder, William Edward Boeing (1881–1956) was present. The prototype made its first flight 15 July 1954 with Boeing test pilots Alvin M. “Tex” Johnston and Richard L. “Dix” Loesch. It is painted yellow and brown.
Originally planned as a turbojet-powered development of the Boeing KC-97 Stratotanker, the Model 367, the 367-80 was the 80th major design revision. It is called the “Dash 80.”
Boeing had risked $16,000,000 in a private venture to build the Dash 80 in order to demonstrate its capabilities to potential civilian and military customers, while rivals Douglas and Lockheed were marketing their own un-built jet airliners. Put into production as the U.S. Air Force KC-135A Stratotanker air refueling tanker and C-135 Stratolifter transport, a civil variant was also produced as the Boeing 707 Stratoliner, the first successful jet airliner. Though they look very similar, the 707 is structurally different than the KC-135 and has a wider fuselage.
The prototype Boeing Model 367-80 was operated by a pilot, co-pilot and flight engineer. The airplane’s wing was mounted low on the fuselage and the engine nacelles were mounted on pylons under the wing, as they were on Boeing’s B-47 Stratojet and B-52 Stratofortress. The wings and tail surfaces were swept to 35° at 25% chord, and had 7° dihedral. The Dash 80 was 127 feet 10 inches long with a wingspan of 129 feet, 8 inches and overall height of 38 feet The tail span is 39 feet, 8 inches, The empty weight of the 367-80 was 75,630 pounds, and the gross weight, 190,000 pounds.
N70700 was powered by four Pratt & Whitney Turbo Wasp JT3C engines. These gave the 367-80 a cruise speed of 550 miles per hour, and a maximum speed of 0.84 Mach at 25,000 feet.
Boeing continued to use the 367–80 for testing, finally retiring it 22 January 1970. At that time, its logbook showed 2,346 hours, 46 minutes of flight time . It was flown to Davis-Monthan Air Force Base, Tucson, Arizona, and placed in storage. In 1990, Boeing returned it to flyable condition and flew it back it to Renton where a total restoration was completed. Many of those who had worked on the Dash 80, including Tex Johnston, were aboard.
The pioneering airplane was presented to the Smithsonian Institution and is on display at the National Air and Space Museum, Steven V. Udvar-Hazy Center. The Boeing 367-80 was designated an International Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers.
820 of the C-135 series and 1,010 Model 707 aircraft were built from 1957–1979.