Curtiss P-40, known to Americans as Warhawk, and to their allies of the British Commonwealth as Tomahawk and Kittyhawk, fought on nearly all fronts of the Second World War, serving with the American, British, Australian, New Zealand, South African, Canadian, Free French, Chinese, Dutch and Soviet air forces.
The American Warhawks were part of as many as nine US Army Air Forces stationed overseas: the 5th (Australia, New Guinea, Philippines); the 6th (Central America); the 7th (central Pacific); the 9th (Middle East, North Africa), the 10th (India, Burma), the 11th (Alaska, Aleutians), the 12th (North Africa, Italy); the 13th (the Solomons); and the 14th (China). During the first years of the war the P-40 helped the Allies stem the offensive of the Axis powers and fight them back at the last-ditch defensive positions, like Kunming in China, Port Moresby on New Guinea, Darwin in Australia or El Alamein in Egypt. Never a high-performance fighter, it nonetheless proved a potent weapon in capable hands. Often turned into a fighter-bomber in later years, it soldiered on until phased out in favor of more advanced designs.
The origin and development
The prototype, XP-40, was first flown in October 1938. Deliveries to the USAAC commenced in June 1940. The aircraft caught attention of several countries. The French ordered a batch of Hawk 81A fighters, which was the export version of the P-40, but France was overrun by the Germans shortly afterwards. The French order was taken over by the British, who gave the aircraft their own name – Tomahawk Mk I. Soon Curtiss came up with an improved version, more heavily armed and armored, with self-sealing coating for fuel tanks. The P-40B, first flown in March 1941, was named Tomahawk Mk IIA by the RAF. Two months later Curtiss made available P-40C (Tomahawk Mk IIB to the British) with provision for mounting a drop tank or a bomb on the centerline rack. The aircraft’s weight increased, and its performance suffered accordingly.
Most P-40Bs and -Cs received by the USAAC were shipped to units stationed in the Pacific. The British took great interest in the P-40C, eventually ordering close to 1,000 of them. The RAF used Tomahawk Mk IIBs mostly in North Africa. Many were delivered to air forces of Commonwealth countries (SAAF, RAAF and RCAF). After the Germans had invaded the Soviet Union, some 200 Tomahawk Mk IIBs were offered to Russians. Another 100 found their way to China, where they were flown by pilots of the American Volunteer Group, better known as the ‘Flying Tigers’.
Meanwhile Curtiss constructed P-40D with a more powerful engine. The new, bigger powerplant left no room for cowl guns, hence from then on machine guns were mounted only in wings. Whilst the USAAC soon shifted its interest to a yet newer version, the P-40D was practically bought up by the British, who called it Kittyhawk Mk I (overall, the RAF received 560 aircraft of this version, delivered between August and December 1941).
Concurrently with the P-40D, Curtiss designed P-40E – more powerfully armed (with six half-inch machine guns) and fitted with armor plate protecting the pilot’s head from behind, but substantially heavier (which adversely affected the aircraft’s ceiling, range and climb rate). Deliveries of the P-40E began in August 1941 and terminated in May 1942. Only three USAAC fighter squadrons, all of them stationed in the Philippines, were converted to the type before the war in the Pacific broke out. Again the British were eager to get as many as there were available, eventually receiving 1,500 (under Lend-Lease provisions). In the RAF the P-40E was known as Kittyhawk Mk IA. Many were handed over to other Allies – mostly to the Soviet Union (691) and Australia (163).
A major drawback of all the hitherto produced P-40s was poor performance above 15,000 feet, which resulted from the use of Allison engine with one-speed supercharger. When Packard company from Detroit started a licensed production of British Rolls-Royce Merlin engines with two-speed supercharger, the USAAC ordered Curtiss to design a P-40 powered by this engine. The effect was the P-40F. Its maximum speed was no different from the P-40E, but the P-40F could reach it at much higher altitude. Moreover, initial climb rate and tactical ceiling improved considerably. The most visible difference between the P-40F and the preceding versions was its rear fuselage, which was lengthened by 25.72 inches (starting with P-40F-5 variant) in order to improve lateral stability. Curtiss delivered over 1,300 P-40Fs between August 1942 and January 1943. The British, who received only 150 aircraft (of the early, short-tailed P-40F-1 variant), called it Kittyhawk Mk II.
Curtiss concurrently designed P-40K – another version powered by the ‘old’ Allison engine, only with a little more takeoff power. Beginning with P-40K-10 variant, the fuselage was lengthened in the same manner as in P-40F. Overall, 1,300 P-40Ks were delivered between May and November 1942. The British, who received 300, named it Kittyhawk Mk III.