When Shenyang rolled the FC-31 Gyrfalcon out of its hangar in 2012, nobody took it seriously. The aircraft had no customer, used Russian engines, and had lost the competition to the J-20. Fourteen years later, the same airframe has produced two operational variants — the carrier-based J-35B launching from China’s first EMALS aircraft carrier, and the land-based J-35A entering frontline PLA Air Force service. Pakistan looks set to take 40 planes.…