KB-50 Tankers
The Boeing KB-50 was a modified Boeing B-50 Superfortress for air refueling needs by the United States Air Force. Two primary tanker versions were developed and produced, the KB-50J and the KB-50K.
After the promising results from the KB-29 conversions the USAF recognized the need for a tanker with higher performance and more room for off-loading fuel. Soon after entering service as strategic bombers plans were made for converting 134 B-50s, made up of B-50As, RB-50s, and B-50Ds, into aerial refueling tankers when no longer needed by Strategic Air Command bomber forces. As tankers, KB-50s would feature extensively reinforced outer wing panels, as well as the necessary equipment to air refuel simultaneously three fighter-type aircraft by the probe and drogue method. The modifications, assigned to the Hayes Aircraft Corporation, also included deletion of the B-50 defensive armament and replacement of the aircraft's tail section. Although the completion date of the Hayes modification was tentatively set for December 1957, the project (ordered in the mid-1950s) proceeded so well that it was ended ahead of schedule.
The first KB-50 flew in December 1955 and was accepted by the Air Force in January 1956. The tankers steadily entered the operational inventory of Tactical Air Command (TAC) supplanting TACs KB-29s. By the end of 1957 all of the command's aerial refuling squadrons had their full complement of KB-50s. TAC had nothing but praise for the new tankers; the KB-50s presented no serious problems, and their reliability was such that the command considered asking for more of them. Extra KB-50s would come "cheap," TAC calculated, if additional numbers of B-50s were added to the Hayes modification line. Nevertheless, the recommendation remained in limbo, which was just as well since the modification line had already been closed and the superior KB-50J was on the way.
Read more about this topic: Boeing B-50 Superfortress