Boeing YB-47F Stratojet

Last revised June 21, 2000



From the inception of the B-47 program, it had been recognized that the development of efficient in-flight refuelling techniques would be absolutely essential for the full success of the relatively short-ranged Stratojet bomber. The first USAF in-flight refuelling tankers were converted B-29 and B-50 bombers, but by the mid-1950s the standard USAF tanker was the piston-engined Boeing KC-97. However, the use of the propeller-driven KC-97 as the tanker for the jet-powered B-47 had its drawbacks, since it could not climb to the B-47's best altitude, forcing the Stratojet to descend down to the tanker's level, wasting time and fuel. In addition, the KC-97 tanker was so slow that the B-47 tended to stall during the refuelling operation. In order to keep the B-47 from stalling, the slower KC-97 would often enter a shallow dive to pick up speed--a hair-raising operation for all concerned while the two planes were linked.

Clearly, aerial tankers with greater speeds would be required. In early 1953, two B-47Bs were allocated for tests with the British-developed probe-and-drogue aerial refuelling system. One was to be a tanker and the other a receiver. The converted aircraft were redesignated KB-47G and YB-47F respectively.

The YB-47F was a conversion of B-47B serial number 50-069. It was fitted with a probe in the nose for inflight refueling via the probe-and-drogue system. Unfortunately, the probe-and-drogue refuelling method did not prove to be effective for the B-47, and subsequent models were refuelled by the established flying-boom system. The speed problem was eventually solved by adding auxiliary jet engines to the piston-engined KB-50 and KC-97 tankers, which were used to provided additional bursts of speed during the refuelling operations.

Sources:


  1. American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.

  2. Post World War II Bombers, Marcelle Size Knaack, Office of Air Force History, 1988.

  3. The Boeing B-47, Peter Bowers, Aircraft in Profile, Doubleday, 1968.

  4. Boeing Aircraft Since 1916, Peter M. Bowers, Naval Institute Press, 1989.

  5. United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.