The Central Intelligence Agency and Overhead Reconnaissance; the U-2 and Oxcart Programs, 1954-1974

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Secret NOFORN
Chapter 2

LeVier made an additional 19 flights in article 341 before moving on to other Lockheed flight test programs in early September. This first phase of U-2 testing explored the craft's stall envelope, took the aircraft to its maximum stress limit (2.5 g's), and explored its speed potential. LeVier soon flew the aircraft at its maximum speed of Mach 0.85. Flight tests continued, with the U-2 ascending to altitudes never before attained in sustained flight. On 16 August LeVier took the aircraft up to 52,000 feet. In preparation for this flight, the 42-year-old test pilot completed the Air Force partial-pressure suit training program, becoming the oldest pilot to do so. Testing at even higher altitudes continued, and on 8 September the U-2 reached its initial design altitude of 65,600 feet. $ ^{45} $

On 22 September 1955, the U-2 experienced its first flameout at 64,000 feet—more than 12 miles up. After a brief restart, the J57/ P-37 engine again flamed out at 60,000 feet, and the aircraft descended to 35,000 feet before the engine could be relit. Engineers from Pratt & Whitney immediately set to work on this problem. The P-37 model engine had significantly poorer combustion characteristics than the preferred but unavailable P-31 version and therefore tended to flame out at high altitudes. Combustion problems usually became apparent as the U-2 began the final part of its climb from 57,000 to 65,000 feet, causing pilots to refer to this area as the "badlands" or the "chimney." Flameouts bedeviled the U-2 project until sufficient numbers of the more powerful P-31 engines became available in the spring of 1956. $ ^{46} $

Meanwhile, with the airworthiness of the U-2 airframe proven, Lockheed set up a production line in the Skunk Works, but delivery of even the second-choice J57/P-37 engines became a major problem. Pratt & Whitney's full production capacity for these engines for the next year was contracted to the Air Force for use in F-100 fighters and KC-135 tankers. Colonel Geary, with the help of a colleague in the Air Force Materiel Command, managed to arrange the diversion of a number of these engines from a shipment destined for Boeing's KC-135 production line, making it possible to continue building the U-2s. $ ^{47} $