The Curtiss P-40 Kittyhawk, Warhawk and Tomahawk versions, developed from the strengths of the P36. It was America's top in service fighter when WWII began. P-40s intercepted Japanese zeros and bombers during the attack on Pearl Harbour and during the invasion of the Philippines in December 1941. They were also flown in China early in 1942 by American Pilots in the Flying Tigers squadron and in North Africa in 1943 by the first all-black unit, the 99th Fighter squadron

More than 14,000 P-40 Kittyhawk were constructed for service in the air forces of 28 nations. 2,320 were of the "P-40 E" series. The Curtiss P-40 Kittyhawk served in many different combat areas like the Aleutian Islands, Italy, the Middle East, the Far East, the Southwest Pacific and some were sent to Russia. P-40 earned a reputation in battle for extreme ruggedness but it was often outclassed by its adversaries in speed, manoeuvrability and rate of climb.

The P-40 Kittyhawk's maximum speed was 362 mph and its cruising speed was 235 mph. It had a range of 850 miles with a service ceiling of 30,000 ft. Its armament consisted of six .50-cal. machine guns and could carry 700 lbs. of bombs externally. In 1941 the American Volunteer Group (A.V.G) nicknamed the Flying Tigers was formed by retired Air Corps major Claire L Chennault who had served as special advisor to the Chinese Air Force. It consisted of about 100 pilots with 200 groundcrew personnel. Most had been released from the U.S. Army, Navy, and Marines to volunteer for the A.V.G. It was a great way to get American Pilots combat training during peace time. The unit was equipped with then obsolescent Curtiss P-40B Kittyhawks.

Two of the three squadrons protected the Burma Road, the only ground route into China, from Kunming. Contrary to popular belief, the AVG did not fire their guns in anger until AFTER Pearl Harbor. On 20th December 1941, the Flying Tigers received their "baptism under fire". They inflicted heavy losses on a Japanese bomber squadron by destroying six out of ten attacking Japanese Ki 21 bombers. On 23rd December the Flying Tigers lost two pilots because the AVG underestimated the manoeuvrability of the Japanese army fighter, the Nakajima Ki 43 Hayabusa (code named Oscar).

The AVG P-40s never encountered the Japanese A6M Zero-sen in combat as they were being used in the Pacific. But at that stage of the war, virtually every Japanese single-seat fighter was called a "Zero". The best tactic was found to be a diving pass followed by a rapid exit from the scene, thus using the P-40's superior speed and diving ability to maximum advantage. The famous "shark's teeth" marking did not originate with the AVG Flying Tigers. They were copied from the markings used by the Curtiss P40 Tomahawks of the RAF's No. 112 Squadron in North Africa.

During the following months of combat missions the A.V.G. scored a very impressive record against the enemy, 286 Japanese planes shot down at a cost of 12 A.V.G. pilots killed. They were normally greatly outnumbered in the air. There were no replacement pilots and practically no spare parts for repairing aircraft. 30 P-40Es were issued to the AVG. Four Curtiss Kittyhawk machines were lost in combat. Some were lost in Japanese strafing attacks on airfields and many had to be cannibalised to keep others in the air. In May 1942, with America now in the war, pilots of the 23rd Fighter Group, replaced the Flying Tigers. The A.V.G. was dissolved on 4th July 1942 when the 23rd Group was officially activated.

On Jul. 19, 1941, the Army Air Force (AAF) began a program in Alabama to train black Americans as military pilots. The first group of black airmen were trained to be fighter pilots for the 99th Fighter Squadron, slated for combat duty in North Africa, kitted out with P-40s. Additional pilots were assigned to the 332d Fighter Group which flew combat along with the 99th Squadron from bases in Italy. By the end of the war, 992 men had graduated from pilot training at Tuskegee, Alabama, 450 were sent overseas for combat assignment. Approximately 150 lost their lives while in training or on combat flights.

The French government ordered 140 P-40s for their Armee de l"Air. The French Airforce called them Hawk 81-A1. They were identical to the US P-40 except that they had French instruments and equipment. Before any of the H81-A1s could be delivered, France surrendered. The British Government agreed to take over the French order. The RAF re-christened them Tomahawk I. In September of 1940, the first Tomahawk I's reached England. The two 0.5-inch machine guns in the nose were retained, but four wing-mounted 0.303-inch Browning machine guns were added to the wings The RAF quickly concluded that these planes were not suitable for combat over Europe as they lacked armour protection for the pilot, armour-glass windshields, and self-sealing fuel tanks but as a German invasion of Britain was feared to be imminent, they were issued to several operational squadrons.

The Battle of Britain change Hitler's mind about invading Britain so the Tomahawk Is were used only for training roles. The RAF Desert Air Force squadron was equipped with Tomahawks. They replaced Gloster Gladiators. No 112 Squadron became famous for adding its "shark's tooth" insignia on the engine cowling, and this paint scheme was later adopted by the American Volunteer Group The Flying tigers in China. In June 1941, one hundred and ninety-five Tomahawk IIBs were shipped to Russia after the German invasion. Some were shipped directly from America but others were sent from the RAF's invasion defence squadrons. As the German invasion never came they were surplus to requirements. In October 1941 Russian Tomahawks saw action over the Moscow and Leningrad fronts. They were the first American built planes to be flown by the Russians Airforce.

Much of the enemy opposition to the RAF Tomahawk IIs in the Middle East was provided by obsolescent fighter biplanes like the Fiat CR-42 and underpowered, lightly armed fighter monoplanes such as the Fiat G-50 of the Italian Air force. The Tomahawk P-40s had difficulty with the more advanced Macchi C-202 Folgore. At low altitudes, the Tomahawk II was superior to the ME 109, but this advantage rapidly disappeared when combat took place at altitudes above 15,000 feet. The weight of the aircraft's rugged structure handicapped the planes performance, but it meant that it could absorb a terrific amount of battle damage and still allow the airplane to return to base. Wing Commander Clive Caldwell of the RAAF scored more than twenty victories while flying a Tomahawk in the Middle East.

The original P-40s were fitted with an Allison engine. In 1941, P-40D was fitted with a 1300 hp British-built Rolls-Royce Merlin 28 engine. These more powerful British engines did much to overcome the performance limitations of the Allison engine, The P-40F and later versions were known by the name *Warhawk* in US service. One hundred and fifty P-40Fs were sent to the RAF under Lend-Lease. The RAF gave them the name Kittyhawk II. By the summer of 1943, the performance of the P-40 Warhawk was leaving much to be desired. The P-40N was known as Kittyhawk IV in RAF service. The last production Warhawk was a P-40N which left the assembly line on 30 November 1944, being the 13,739th P-40 built.

In the later part of the war these aircraft were used in the Pacific in fighter-bomber or escort roles, most of them flown by RAF, RAAF, and RNZAF pilots. The USAAF service, used them in training roles, as the P-51 Mustang or the P-47 Thunderbolt became increasingly available in quantity. Most of the RAF Kittyhawk IVs were phased out of service early in 1945, but one RAF squadron continued to operate the Kittyhawk IV until the end of hostilities. RAF squadrons equipped with the P-40N included Nos 112, 250, and 450.

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