The 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 which reduced development time and enabled a rapid entry into production and operational service. The Warhawk was used by 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 P51 and P47.