<hi style=afpcap>The KC-135 and all other aircraft in the C-135 family were from the Boeing 717 series, which was slightly smaller than the commercial 707 model, with more than 800 being ordered between 1955 and 1964. The Air Force also obtained three Boeing 707 models for Presidential use with the designation VC-137A, being very similar to the civilian version, but with a full VIP suite installed. These were obtained in 1958 for President Eisenhower, and were later modified to VC-137B standard with the fitment of TF33 turbofan engines in place of the J57 turbojets. During presidential flights the aircraft used the call sign 'Air Force One' which subsequently became the nickname of the C-137s. In 1962 a new example designated the VC-137C was obtained for President Kennedy, with another being ordered in 1972. All five have changed designation with the deletion of the V prefix, and remain in service, although they no longer perform 'Air Force One' duties as this role is now conducted by a pair of Boeing VC-25As based on the 747 model. </hi>
