KB-50s were B-50 bombers modified as aerial tankers, generally after they had become surplus to Strategic Air Command requirements. These alterations involved the removal of armament and the installation of additional fuel tanks and probe-and-drogue equipment to permit the aerial refueling by hose of up to three fighter-type aircraft at one time. KB-50s went into service with the Tactical Air Command in 1957. As the performance of operational jet fighters increased, a J47 jet engine was installed under each wing on some KB-50s to boost speed while refueling and to increase altitude capability. Hayes Aircraft Corp. converted 136 tankers in this manner (KB-50Js and Ks). Deliveries of these improved tankers to TAC began in early 1958. They were replaced by jet KC-135 tankers in the mid-1960s, but a few were still available in 1965 for use in Southeast Asia for emergency refueling of fighters over hostile territory.
The KB-50Js were all converted B-50Ds and were originally designated KB-50. These aircraft had the refueling hose assemblies installed, but not the jet engines. When Hayes Aircraft Corp. fitted the J47 jet engines, the designation was changed to KB-50J for all ex-B-50Ds. The K models were modified TB-50Hs.
The National Museum of the United States Air Force had at one time a KB-50J (S/N 49-0389), but it was transferred to another museum in 1996.
In-flight refueling tanker
TECHNICAL NOTES: Armament: None Engines: Four Pratt & Whitney R-4360-35 Wasp Major turbosupercharged radials of 3,500 hp each and two General Electric J47 turbojets of 5,910 lbs. thrust each Maximum speed: 445 mph Cruising speed: 410 mph Range: 2,500 miles Service ceiling: 40,000 ft. Span: 141 ft. 2 in. Length: 105 ft. 1 in. Height: 32 ft. 7 in. Weight: 178,500 lbs. Crew: Eight