The Royal Air Force’s early test programs involved joining two aircraft together with trailing lead lines, after which a crewman on the receiving plane dragged the refueling hose to the fill receptacle using brute force. The British later perfected that technique. In fact, the first private enterprise dedicated to aerial refueling, Flight Refuelling Limited, was started in 1934 by re­nowned British aviator Sir Alan Cob­ham, whose company developed equipment that has long supplied tankers with hoses and “probe-and-drogue” receptacle systems.

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Part of FRL’s development work focused on commercial aviation, envisioning a future in which trans­atlantic and other long-distance routes became a matter of routine. But although experiments done toward that end, such as one performed in 1929 along a U.S. transcontinental mail route, were on the whole successful, they never attracted customers. Commercial pilots were not enthusiastic about IFR, and it was thought passengers would be even less so.

The Allies conducted successful air-to-air tests during WWII, in­cluding one in which a Consolidated B-24 refueled a Boeing B-17. But the Luftwaffe’s defeat in the Battle of Britain, coupled with Allied successes in North Africa and Italy, ensured that American aircraft would not be forced to fly grueling transatlantic missions. In the Pa­cific, the introduction of the long-range Boeing B-29 and North Ameri­can P-51 meant that bombers and their escorts could reach Japanese targets and return to base without the need for IFR.

Following WWII, the Communist threat that fostered the Cold War made IFR a growing American priority. The mission for Strategic Air Command, formed in 1946, became preparation and visibility, and refueling was an integral part of both. In 1948 the U.S. Air Force purchased two sets of Cobham’s IFR hardware, manufacturing rights to FRL’s system, a contract for 40 additional sets and a year of technical support. The first IFR squadrons were established at Davis-Monthan Air Force Base and Roswell Air Force Base in 1948, at a time when Lt. Gen. Curtis E. LeMay was launching operations to showcase the strength of America’s strategic bomber force.

This new emphasis on strategic bombing produced the first dedicated air tanker, the KB-29M, a modified B-29 Superfortress. When operations commenced with the KB-29 and KB-50 (a tanker developed from the B-50 design update of the B-29), they relied on the reel hose and drogue method developed by the U.S. subsidiary of FRL. The drogue was an aerodynamically de­signed basket that the probe of the receiver aircraft locked into during the refueling process. But the system had its problems: Hooking up with the tanker was tricky for pilots, the pumping process was slow and crewmen found it difficult to keep the fuel-laden hose stable during fueling. Despite these difficulties, the exigencies of the Cold War demanded IFR capability, and the probe-and-drogue method worked. Some KB-29 and KB-50 refuelers were equipped with wingtip hose reels in addition to the standard fuselage assembly, enabling simultaneous refueling of three fighters or other smaller aircraft.

By the late 1940s, however, SAC was looking for a way to transfer more fuel faster to accommodate its new fleet of gas-guzzling jets. After approaching Boeing, SAC vacillated on the project, but Boeing continued working on the problem. Its research department started looking into possible configurations for a “flying boom,” a telescoping aluminum tube extending from the tanker. The name is appropriate because the boom operator controls the flying boom’s azimuth and elevation with a dual-wing “ruddervator” on the boom shaft. One of the ideas called for the boom to telescope upward from a B-29 forward gunner’s position, with the tanker trailing the receiver aircraft. Ultimately aerodynamics, safety and efficiency prompted designers to have the boom extend from the lower rear fuselage of the tanker toward the nose of a receiver plane, flying behind and below.

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