In fighters, North American Aviation was in the midst of working on a straight-wing jet-powered naval fighter, then known as the FJ-1; it was later submitted to the United States Air Force as the XP-86.[64] Larry Green, who could read German, studied the Busemann reports and convinced management to allow a redesign starting in August 1945.[2][65][66] The performance of the F-86A allowed it set the first of several official world speed records, attaining 671 miles per hour (1,080 km/h) on 15 September 1948, flown by Major Richard L. Johnson.[67] With the appearance of the MiG-15, the F-86 was rushed into combat, while straight-wing jets like the Lockheed P-80 Shooting Star and Republic F-84 Thunderjet were quickly relegated to ground attack missions. Some, such as the F-84 and Grumman F-9 Cougar, were later redesigned with swept wings from straight-winged aircraft.[68][69] Later planes, such as the North American F-100 Super Sabre, would be designed with swept wings from the start, though additional innovations such as the afterburner, area-rule and new control surfaces would be necessary to master supersonic flight.[70][9]