When did the plane that the Vought XF8U-3 Crusader II was designed to compete against enter service with the U.S. Navy?
Vought XF8U-3 Crusader III: The Vought XF8U-3 Crusader III was an aircraft developed by Chance Vought as a successor to the successful Vought F-8 Crusader program and as a competitor to the McDonnell Douglas F-4 Phantom II. McDonnell Douglas F-4 Phantom II:  It first entered service in 1960 with the U.S. Navy.
1960