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"The P-47 originated with a June 1940 proposal by Republic designer Alexander Kartveli to base a fighter on the new Pratt & Whitney R-2800 twin-row radial engine, turbo-supercharged for high-altitude performance. Harnessing the power of the huge engine posed problems, and the first prototype did not fly until June 1941. Production did not commence until March 1942, and even then difficulties were caused by shock waves that formed in high-altitude dives when the local airflow approached the speed of sound, causing the flight controls to "snatch" and in some cases lock. The controllability problems were eventually resolved, but it was mid-April 1943 before the P-47 entered combat over Europe."

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