KC-135 Refueling B-52 Stratofortress
The Boeing KC-135 Stratotanker is an aerial refueling tanker used by USAF. It was the first jet powered aerial refueling tanker, replacing the propeller driven KC-97.
The KC-97 was a derivative of the B-29 Superfortress also built and designed by Boeing. The KC-135 went into service in 1957 and has been in service now 59 years and is estimated to be used until 2040
The KC-135 was born around the 1952-1953 time period. The military wanted an jet-powered tanker and Boeing had built a Boeing 367-80 prototype that eventually became the forerunner for the B-707 series.