The Curtiss P-40 Warhawk was an American single-engine, single-seat, all-metal fighter and ground attack aircraft that first flew in 1938. The P-40 design was a modification of the previous Curtiss P-36 Hawk which reduced development time and enabled a rapid entry into production and operational service. The Warhawk was used by the air forces of 28 nations, including those of most Allied powers during World War II, and remained in front line service until the end of the war. It was the third most-produced American fighter, after the P-51 and P-47; by November 1944, when production of the P-40 ceased, 13,738 had been built, all at Curtiss-Wright Corporation's main production facilities at Buffalo, New York.