The production P-40 (Model 81A) were nearly identical to the XP-40, but was built with a 1,040 hp (780 kW) V-1710-33s and one .30 M1919 Browning in each wing. The company designation was changed to Model 81 due to the extensive changes from the standard Model 75. France, who was a large operator of the P-36, was interested in this fighter and ordered 140 aircraft as Hawk 81A-1s. However, following the 1940 French Armistice the Royal Air Force acquired these aircraft as Tomahawk Mk.Is. This variant was not considered combat-ready, as they lacked heavy armament and armor, but as there was a shortage of decent fighter aircraft after the Battle of Britain, the RAF pressed these into service for use in North Africa anyway.

Though strongly built, the first P-40 variant was poorly protected and lacked armor and self sealing tanks. This was partly rectified with the P-40B, which had additional armor behind the cockpit, but fuel system and control line vulnerability remained a problem to some extent with all Tomahawk types. The P-40B also had an additional .30 MG in each wing.

Info: P-40B Tomahawk - 78th Pursuit Sqn (18th Pursuit Group), Bellows Field, Pearl Harbor, 7 Dec. 1941