A framed photograph of a North American F-86 Sabre being tested in a wind tunnel. In the autumn of 1944 the Army Air Forces ordered three prototypes of a modified North American FJ-1 Fury, a jet fighter being developed for the Navy. It was designated the XP-86. The design progressed through the mock-up stage, but by the summer of 1945 it was apparent that the fighter's top speed would be well below the 600 mph called for in the specification. Fortunately, a great deal of captured German aerodynamic data became available to the North American designers with the surrender of Germany in May 1945. These data indicated that a swept wing delayed the compressibility effects encountered at high subsonic speeds. Swept winged aircraft could be controlled at a considerably higher Mach number than a straight winged aircraft of the same general configuration. The swept wing, however, introduced low-speed stability problems. After scale model wind tunnel tests, the designers selected a wing that was swept back at an angle of 35 degrees, and added automatic leading edge slats to solve the stability problem. The first XP-86 flew on October 1, 1947, powered by an Allison J35-C-3 engine. In April 1948, the XP-86 exceeded Mach 1 in a shallow dive. On September 15, 1948, an F-86A set a world speed record of 671 mph.