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.
In the autumn of 1942 Curtiss attempted to reduce the P-40’s weight, hoping to boost its performance. Most importantly, one pair of machine guns was removed, as well as the front fuel tank in wings and some of the protective armor. The end result was P-40L, which was basically a lightened version of the P-40F. In the first months of 1943 Curtiss produced 700 aircraft of this version. The ‘slimming’ operation proved of little value, because the reduction of weight by some 200 kg had only a marginal effect on the aircraft’s performance. In the event, field workshops often put back the removed items. The British, who were offered 100 P-40Ls, gave them the same designation as to the earlier P-40Fs – Kittyhawk Mk II.
Despite the obvious shortcomings of the Allison-powered P-40s, Curtiss continued to develop and produce them. The main reason was the fact that priority in deliveries of Merlin/Packard engines was given to the production of P-51 Mustangs. Therefore, Curtiss had no qualms about designing P-40M, which was coupled to an engine of more durability but less takeoff power (as compared to the P-40K), which resulted in further deterioration of the aircraft’s performance, especially its maximum speed. Most of the 600 P-40Ms, which were produced at the turn of 1942/43, were handed over to America’s allies, mainly Australia and USSR. The British called them Kittyhawk Mk III (same name as for the earlier P-40K). Of the 264 aircraft they received, the British passed as many as 170 to Russians, who additionally took a delivery of 90 directly from Americans. In fact, few P-40Ms served in the USAAF or the RAF.
In early 1943 Curtiss designers undertook another attempt of improving their fighter’s performance. Again they tried to achieve it by reducing the aircraft’s weight, this time even more drastically. The P-40N, initially lightened by nearly 500 kilograms, indeed proved the fastest serial-produced version of the Warhawk. However, the trade-off was unacceptable and during the production run some of the removed items were put back in place (including battery and the third pair of guns). Although by that time American industry produced fighters of much better performance, eventually no fewer than 5,520 P-40Ns were built! Most of those received by the USAAF were shipped to Asia and the Pacific. The British used their share in Italy, under the name of Kittyhawk Mk IV. Over 1,100 were supplied to Russians.
All in all, from March 1940 until November 1944 nearly 14,000 P-40s of all versions and variants were constructed. Of those, only 2,011 were powered by Merlin/Packard engines.
P-40, due to its unsatisfactory performance at high altitude, wasn’t of much use over north-western Europe. However, it was there that it scored by all means a historic victory. Beginning with August 1941, the Americans provided Iceland with fighter cover, deploying 33rd PS for that purpose. The squadron, equipped with P-40Cs, performed defensive patrols over the island. During one of them, on 14th August 1942, 2/Lt. Joseph Shaffer intercepted a reconnaissance Focke-Wulf 200 Condor and teamed up with a P-38 pilot to shoot it down. It was the first victory by a US Air Force fighter over a Luftwaffe aircraft in WWII – at least partially scored by a P-40. The squadron remained at Iceland until the war’s end (as part of 342nd Composite Group), with time converting to P-47 Thunderbolts.
Of all the Second World War fronts, the P-40 is most readily associated with China, the operational area of the famed ‘Flying Tigers’ aka. AVG. During their relatively short combat career (December 1941 – July 1942) they made a lasting impression on friend and foe alike. Initially they were equipped with 100 early P-40s from a British order. The machines from this batch differed from one another, but most were of P-40B (Tomahawk Mk IIA) standard. First P-40Es didn’t arrive in China until March 1942. The AVG pilots took the idea of painting the distinctive ‘shark jaws’ on their P-40s from the British of No 112 Sqn RAF, at that time fighting in North Africa.
During the first weeks AVG fought in defense of Rangoon, the capital of Burma (then a British colony). Steadily pushed to the north, it retreated to its base at Kunming in China, where it continued to fight off Japanese air raids. In spring 1942 the three squadrons of the AVG intensified offensive operations, moving part of their force to eastern China to attack Japanese airbases and seaports on the coast of South China Sea, especially Canton and Hong Kong. In July 1942 the unit was disbanded and replaced by a regular USAAF fighter group – 23rd FG – which took over some veterans and equipment of the ‘Flying Tigers’. The AVG pilots were credited with 296 Japanese aircraft destroyed in the air and on the ground. As many as 18 ‘Flying Tigers’ became aces with five or more victories to their credit (the top-scorer was Robert Neal with 13). The 23rd FG continued to harass the Japanese in China. General Claire Chennault, the father of the ‘Flying Tigers’ and later the commander of the US 14th Army Air Force (constituted in March 1943), successively bolstered his forces with Warhawk squadrons of 51st FG brought from India.
Late 1943 saw combat debut of Chinese-American Composite Wing (CACW), partially equipped with Warhawks. At the same time first P-51 Mustangs began to arrive in China. However, they were so few that P-40s continued to serve with fighter squadrons of 14th AF for another year or so. In late June 1944 the strength of 23rd FG was bolstered by the arrival of 118th TRS, a tactical reconnaissance squadron equipped with P-40Ns, which had earlier served in India. Not all Warhawks of the US 10th Army Air Force went to China. The Tenth retained 80th FG, which arrived in India at the turn of 1943/44. This group mainly operated over the Japanese-occupied Burma (hence its nickname ‘Burma Banshees’).
P-40 saw as much combat in the vast expanses of the Pacific, from the Aleutians to Australia. In Pearl Harbor, on 7th December 1941, there were two Pursuit Groups (15th and 18th1) equipped with some 100 P-40B/Cs in all. Nearly all of them were either destroyed or damaged on the ground. Only a handful of pilots managed to get airborne. Two of them (both of 47th PS) made the name for themselves – 2/Lt. George Welch shot down four Japanese aircraft, and 2/Lt. Kenneth Taylor two. Also in the Philippines about 100 Warhawks (of 24th and 35th PGs), most of them the latest P-40Es, were stationed when the war in the Pacific broke out. Here the result of the first clash with the Japanese was very much the same as in Pearl Harbor. This first air battle for the Philippines also had its hero – on 12th December 1941 Lt. Boyd ‘Buzz’ Wagner of 24th PG shot down four Japanese fighters in a skirmish over Aparri airfield. Four days later he got another and became the first ace of the US Army Air Corps. In February 1942 Warhawk pilots, grouped in an improvised squadron called 17th PS (Provisional), fought a desperate battle for the island of Java, tallying 40 victories but losing 17 aircraft. The top-ranking pilot of the squadron was 2/Lt. William Hennon, who shot down five Japanese aircraft.
The veterans of the Philippines and Java joined 49th PG, which arrived in Australia from the USA in February 1942. In the following months the group countered Japanese air raids on Darwin. In September 1942, when RAAF units took over the air defense of Australia, the group (which by that time changed designation to 49th FG) moved to New Guinea, the main operational area of the US 5th Army Air Force.
The first P-40s fighting for New Guinea were Australian Kittyhawks of 75 and 76 Squadrons RAAF, from March and July 1942 respectively. A third squadron, 77 Sqn RAAF, joined them in February 1943. By the end of 1943 the Australians equipped five more fighter squadrons (78, 80, 82, 84 and 86) with Kittyhawks. The RAAF also fielded a Dutch squadron of Kittyhawks, 120 Sqn NEI. In May 1944 it set up shop at Merauke on New Guinea, and operated over the area of Netherlands East Indies until the end of the war, carrying out coast patrols and occasionally strafing isolated Japanese positions in the area of Vogelkop Peninsula.
Meanwhile the Americans were successively phasing out their P-40s in favor of the long-ranged P-38 Lightnings. In January 1943 one of the three component squadrons of 49th FG converted to P-38s. Since Warhawks were no longer in short supply, in June 35th FS of 8th FG exchanged the unpopular P-39 Airacobras for P-40s, and operated them until it too converted to Lightnings in February 1944. The 35th scored several spectacular successes on Warhawks (P-40Ns). On 16th January 1944 over Saidor on New Guinea, during the squadron’s last engagement before conversion, it tallied a record 19 victories. The two remaining squadrons of 49th FG still operating Warhawks didn’t convert to P-38s until late 1944. In November their combat-weary P-40s were issued to 110th TRS ‘Musketeers’, a tactical reconnaissance squadron. It was a pilot from this unit, 2/Lt. Robert Hammond, who scored the last P-40 victory in the Pacific – on 29th January 1945 he shot down a ‘Zeke’ over Philippines. The following month the squadron converted to F-6 Mustangs.
Concurrently with the prolonged battle for New Guinea, the Americans and their allies fought a campaign in the Solomons, which started with the invasion of Guadalcanal in August 1942. The fighter units of the US 13th Army Air Force stationed there fielded two Warhawk squadrons: 68th FS (of 347th FG) and 44th FS ‘Vampires’ (of 18th FG). The former operated Warhawks until mid-1943, and the latter until November. Also the New Zealanders were heavily involved in the battle for the Solomons, and later in the aerial assault against Rabaul, the Japanese stronghold on New Britain. They operated Kittyhawks until rearming with F4U Corsairs around mid-1944. Overall, nine Kittyhawk squadrons (14, 15, 16, 17, 18, 19, 20, 21 and 22 Sqns RNZAF) were engaged in the Pacific.
Of the US 7th Army Air Force fighter units stationed in central Pacific, Warhawks were operated by 15th FG, at the turn of 1943/44. Only one squadron – 45th FS – found an opportunity to mix it up with the Japanese before the group converted to Mustangs. On 26th January 1944 it clashed with some Zeros over Maloelap Atoll, scoring 10 victories for no losses of its own.