Designing the new plane went smoothly, leading to the first flight of the new XF4U-1 Corsair in May 1940. It was a giant plane when compared to the handy contemporaries, Me-109, I-16 and Zero. The fighter's 18-cylinder engine was the largest motor ever installed in a fighter plane. Utilizing a giant, 4m-diametered propeller, the Corsair received a unique W-shaped wing to guarantee the necessary space for the propellor to operate. Furthermore, the wings had to be large in a surface sense, to hold the stall speed slow.

    There was an odd form of armament contemplated for this new fighter, 20 anti-air bombs, loaded in the wings, plus two .30-caliber guns above the engine and two .50-caliber guns in the wings. With a test flight bringing the fighter to the phenomenal speed of 652 km/h on October 1st 1940, its future was secured and liquid-cooled engines were discarded from future development, as there arose the question what they could do what the R-2800 could not.

    Before the F4U could see service, however, a series of changes had to be made. The bombs were removed, and so were the .30-caliber guns, all replaced by a further four .50-caliber machine guns to supplement the two already in the wings. Without the option of installing fuel tanks in the wings, a large tank had to be put right behind the engine, forcing a backwards movement of the cockpit, and reducing seriously the visibility over the nose.

    With folding wings and a grappling hook, the first order for 584 Corsairs was made in June 1941.  
But, while the F6F Hellcat was very well accepted on the carriers, the Navy found several serious problems with the Corsair, for example it's tendency to bounce on landing and to spin when stalling, and overall those resulted in the assignment of the Corsair to Marine fighter squadrons flying from island bases. It's very good combat record, and it's apparent versatility, proven on Royal Navy carriers and with the Marine Corps, led to the decision to make the Corsair carrier-capable, and in 1944, the first US carrier squadrons were fitted with the plane, exceptionally capable in Kamikaze interception, strike, and night-fighter missions.
    So good was the plane that it remained in development after the war and saw extensive service in Korea, and with French forces in Indo-China. Some versions of later years (1944-onwards) carried four 20mm guns in place of the .50-caliber weapons.