Goodyear FG-1D Corsair
The Corsair was considered by many Japanese pilots to be the best American combat aircraft at any altitude. It was used both as a fighter and a fighter-bomber.
Although the Hellcat had a victory ratio of 19:1 and the Corsair had a ratio of 11:1, some would argue that the Corsair was the better fighter. Whatever the case may be, both planes acted as a one-two punch in the hands of Navy and Marine pilots to knock out the Japanese Navy and Army Air forces.
The Corsair turned out to be so good that it was called upon to do battle in French Indochina, Korea and various other sites of conflict after the end of World War II. It was one of the longest produced and used fighters in history. The last production F4U Corsair came off the assembly line in 1953 and the last combat planes were phased out of the French Flotilla in 1964.
After much research and debate, it appears that the F4U Corsair was the first U.S. single engine fighter to exceed 400 mph-and it did it in its maiden flights!