Approved for Release: 2013/06/25
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Secret NOFORN
Chapter 5
199
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Refueling a U-2 in flight was a very delicate task. When fully loaded with fuel, KC-135 tankers found it difficult to reduce airspeed to 200 knots, the safest speed for refueling a U-2. As for the U-2s, they were in a very vulnerable position when approaching a tanker at 200 knots because their frail wings could not stand much stress. As a result, U-2 pilots had to approach the KC-135 tankers very carefully in order to avoid the vortexes from the wingtips of the tanker and the turbulence caused by the four large jet engines. During the first few years of refueling operations, two U-2s crashed after their wings broke off as they crossed into the turbulent area behind the tankers; one of the pilots was killed.⁶
The in-flight refueling capability was a useful modification to the U-2, but it could not dramatically extend mission length. The main limiting factor remained pilot fatigue, which prevented missions from lasting longer than approximately 10 hours.
U-2 Coverage During the Cuban Missile Crisis
Cuba remained a high-priority target even after the Bay of Pigs invasion failed in April 1961. Soon afterward, Detachment G U-2s began flying monthly missions over Cuba in a program known as Project
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⁶ Ibid., p. 11-12 (TS Codeword).
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Approved for Release: 2013/06/25