Although the Boeing 707 is known worldwide as the machine which took civil aviation from the piston engine era into that of the jet engine, what is very often not known is that its existence was only made possible by the success of its immediate predecessor, the KC - 135, a flying fuel tank used for refueling the strategic B - 52 bomber, also made by Boeing. Although these two models came from the same prototype, the Dash 80, which first flew in July 1954, they were in fact two radically different machines sharing only a limited number of common features. More than 800 KC - 135s were produced...