Curtiss-Wright Corporation which designed and produced P-40 Warhawk fighters designated P-40D and subsequent variants as Hawk 87 series. While the development of P-40D, the European War was broken out. Due to the poor high altitude performance of the Hawk 81 serving British Air Force, they were soon transferred to second-tier units or military aid to other countries.
P-40D with a more powerful V-1710-39 engine, and a new designed nose cowl enhanced cooling ability. Two nose-mounted machine guns on P-40B/C were eliminated and replaced 4 wing-mounted machine guns with 0.5 inch caliber instead of 0.3 inch. The fuselage armour was strengthened as well. On P-40E, wing-mounted 0.5in machine guns were increased to 6's and under wing pylons increased to 3' s. After upgrading of weapons & armour, the enhanced power of P-40E s engine was therefore offset. Flight performance was even much poor. Thus, it highly depended on high speed diving capacity and exploited "boom-and-zoom" tactics in combat.
However, it performed excellent power on ground attack missions.