List of Curtiss P-40 Warhawk variants

The P-40 went through five significant transformations, comprising 10 official variants, in its international military service.

Hawk 81A-1 / P-40B / P-40C / Tomahawk I / Tomahawk IIA and Tomahawk IIB


Twin nose guns, smaller engine cowling, "long" nose
 * Distinguishing Features:

1941–43
 * Time in Service:


 * Major Operators:
 * RAF Army Cooperation Command 1941–43, with 10+ squadrons equipped by early spring 1942. All based in UK.
 * Desert Air Force (DAF) 1941–43: North Africa and Syria
 * Royal Canadian Air Force RCAF squadrons based in the U.K. included 400, 403, 414 and 430 in the Army Cooperation Role.
 * Republic of China Air Force (American Volunteer Group; AVG; “Flying Tigers”) 1941–42: China/Burma/India (CBI)
 * United States Army Air Forces (USAAF) 1941–42: Pearl Harbor, Philippines and Java
 * Военно-воздушные силы (Soviet Air Forces; VVS) 1942–43: Eastern Front (World War II)  and Continuation War

This was a very important type for the allies in the early part of the war. Many were destroyed on the ground at Pearl Harbor and in the Philippines in December 1941 but these aircraft did well in combat with the AVG in China and Burma, and the Tomahawk was an effective fighter available to the RAF in the early months of the Desert War. It was also a small but important part of the Soviet arsenal in 1942, being one of the few types available to them which could take on the Bf 109 on equal terms at the low altitudes where combat took place there.
 * Commentary:

The earliest version (P-40) had only four guns and lacked armor plate or self-sealing tanks, but the British pressed these into service into North Africa anyway as Tomahawk Is. The P-40B (Tomahawk IIa) had armor behind the pilot, an armored windscreen and partially protected fuel tanks, the P-40C (Tomahawk IIb) had a fully protected fuel system, provisions for a drop tank, and became heavier, reducing speed to under 350 mph. The Soviets reportedly stripped the wing guns from some of their Tomahawks to improve performance. Used extensively by the RAF's Army Cooperation Command from February 1941 in developing high speed, low level, tactical reconnaissance for the British Army. Replaced by the Mustang I in mid 1942.

Though the total weight of fire was much lighter than later model P-40's, and the nose armament had a lower ROF due to firing through the propeller arc, the two .50 caliber nose guns were very accurate, hard hitting and could be recharged from within the cockpit in the event of a stoppage. This was an advantage over the early Kittyhawk (P-40D and E) types which often had problems with jammed guns.

There were a variety of differences between the British Commonwealth and US variants, (starting with the guns, .303 instead of .30 caliber) so that there is not actually an exact correlation between specific US variants (P-40B etc.) and British Commonwealth export versions (i.e. 'Tomahawk')

Though strongly built, early P-40's were poorly protected and lacked armor and self sealing tanks. This was gradually rectified with the P-40B and C but fuel system and control line vulnerability remained a problem to some extent with Tomahawk types. Later 'Kittyhawk' and 'Warhawk' models were better protected and more robust. Engine management and trim management were both somewhat complex and taxing with P-40's especially with early versions, with strong rudder pressure required to offset engine torque and frequent trim adjustments needed during rapid speed changes.
 * Problems:

P-40's were more powerful, faster-flying aircraft than the primary and advanced trainers most early-War Allied pilots were familiar with, and transition training was often inadequate or neglected altogether in the early years of the war. The landing gear was also more narrow and not as strong as in fixed gear aircraft (like the Gladiator) or on some Commonwealth fighters such as the Hurricane. As a result novice pilots had a hard time adjusting to the new fighter and there were many accidents on landing and takeoff in the early years of the war, with both Tomahawk and Kittyhawk types. As training improved these problems subsided.

P-40D / P-40E / Kittyhawk Mk 1 / Kittyhawk Mk Ia


Deeper engine cowling, ('definitive' P-40 "Look") four/six wing guns, "short" nose
 * Distinguishing Features:

1941–43
 * Time in Service:


 * Major Operators:
 * USAAF (1941–43) Philippine Islands, Java (NEI), Australia, New Guinea, Guadalcanal, CBI
 * Royal Australian Air Force (RAAF) (1942–43) Kokoda Track, Battle of Milne Bay, Darwin
 * Royal Canadian Air Force (RCAF) (1941-44) Home War Establishment and Aleutian Campaign (1942)
 * Royal New Zealand Air Force (RNZAF) (1942–43) South Pacific
 * DAF (1942) Desert War, principle air superiority fighter for early 1942
 * VVS (mid 1942–43)
 * Chinese Air Force (1943–27 P-40E)

The was the first version armed with wing mounted .50 caliber machine guns. The main (really only) difference between variants is that the P-40D (mostly used by the RAF who got 560 of them as Kittyhawk I) had four guns and the P-40E (with 1,500 used by the RAF as the Kittyhawk Ia) had six guns. More powerful than the P-40B/C in terms of armor, armament and top speed, this was the type which fought as a fighter during the most crucial early period in both the Pacific and North African campaigns. The P-40E played a major role in the defense of Philippines, Java (NEI), Australia and New Guinea in 1942, and with the Desert Air Force (DAF) in intense fighting against the Luftwaffe and Regia Aeronautica also in 1942. The P-40E was also an important type for the Soviets, particularly in the Leningrad area but also in the siege of Moscow and at Stalingrad.
 * Commentary:

In the Desert War the arrival of the heavily armed, fast and maneuverable Kittyhawk led to the accelerated retirement of the Bf 109E and its replacement by the faster and more maneuverable Bf 109F. The top scoring DAF squadrons, including No. 3 Squadron RAAF and No. 112 Squadron RAF, transferred from the Tomahawk to the Kittyhawk, scoring many kills against Luftwaffe and Regia Aeronautica types, helping the DAF to hold on through this tough period. Many RAF and SAAF P-40 units also took heavy casualties - especially as Me 109F variants began to arrive in Theater in late 1941.

As with all P-40's, the main problem was the effective altitude ceiling of ~ 15,000 feet. Above that altitude the single-stage Allison V-1710 engine performed poorly. As a result, unless combat was taking place at low altitude, P-40 pilots often faced attack from above in the opening stages of an interception, a chronic problem which cost many lives and was difficult to adapt to. The P-40D and E variants, while much more heavily armed than the earlier Tomahawk types, were slightly overweight and had a poor rate of climb (a problem that could be partly dealt with by stripping extra equipment from the plane and / or overboosting the engine) and suffered from problems with their 0.50 caliber M2 machineguns. When maneuvering in high G turns the guns would often jam due to the way the ammunition was stored. This was eventually corrected in the P-40E (and all subsequent versions) toward the end of 1942 but it caused frequent gun stoppages in combat until it was.
 * Problems:

P-40K / P-40M / Kittyhawk Mk III


P-40K has expanded fin, later M models had extended tail
 * Distinguishing Features:

1942–43
 * Time in Service:


 * Major Operators:
 * USAAF (1942–43) New Guinea, Guadalcanal, CBI, Mediterranean and Italy
 * RAAF (1942–43) Kokoda Trail, Milne Bay, Darwin
 * Royal New Zealand Air Force (RNZAF) 1942–43 South Pacific
 * RAF (1942-1944) Mediterranean, Balkans and Italy
 * VVS (late 1942–44)

The P-40K was essentially a P-40E with a significantly higher rated Allison engine in it, the V-1710-73 rated at 1,325 hp (and also featuring automatic boost control). The K was initially supposed to be the last P-40 built in large numbers, but the failure of the P-60 program and ongoing problems with the P-39 and P-38 forced the production run to continue. These were the heaviest P-40 variants, but the extra horsepower on the P-40K gave it good performance particularly at low altitude (noticeably better than the P-40E). The more powerful engine caused problems with the torque especially during takeoff, which is why the distinctive tail fin was added to help correct the takeoff swing, later versions had the extended tail also seen on the F/L, M and N versions. In both cases though the P-40K was notably more stable and suffered less from takeoff swing than the P-40E. It also required less frequent trim changes than earlier types.
 * Commentary:

The P-40K was arguably the most important type used by the 10th Air Force in the post- AVG days to establish air superiority in the China/Burma/India theater, achieving dominance over Japanese Army types in that region. In general they performed well in the Pacific and CBI. The P-40M was also an important type for the RAF / Commonwealth forces (with at least 250 delivered as Kittyhawk III, used mainly in the Med and 50 specifically to Australian units) and for the Soviets, who used it primarily for PVO (air defense) and naval aviation units in the Baltic. Several Soviet aces scored many victories while flying the P-40K including M. V Kuznetzov.

Though used mainly as a fighter-bomber in the Med (with P-40 F/L and later lightened variants of the P-40N taking the lead for bomber escort and fighter sweeps), it nevertheless continued to score air to air victories there as well as in the CBI all the way through 1943 and into 1944.

The P-40M was a purely export variant of the K. Though the engine on the P-40M was rated at a much lower 1,200 hp, this was simply a throttle limitation which many pilots ignored if they needed to, i.e. at 57" of mercury the V-1710-39 could produce as much power as the V-1710-73, but with a slightly greater risk of engine failure. The difference between the V-1710-73 on the P-40K and the V-1710-81 on the P-40M boiled down to a strengthened crankshaft better able to take the higher boost pressures which was already being used for emergency power by P-40 pilots going back to the earliest versions. On the other hand the -81 had slightly better power at altitude, and a performance ceiling 1,000 feet higher. P-40M were, like the K designated as Kittyhawk III in Commonwealth service, with 264 delivered to the RAF, 168 to Australia, and 34 delivered to New Zealand. Most of the RAF aircraft were operated in the Med.

The P-40K series were significantly improved over the P-40E, with automatic boost control helping with the complex engine management and machine gun ammunition storage improved reducing gun stoppages. The main problems remaining were the effective performance ceiling of ~ 15,000 and the takeoff swing and torque issues due to the more powerful engine, which was partially addressed by the tail fin and more satisfactorily by the lengthened fuselage in later models. Due to the heavier weight, at least when fully loaded, initial climb rate suffered. This could be addressed via lightening the aircraft (reducing fuel etc.) or by overboosting the engine which was used in combat to get shots at enemy fighters which attacked and then climbed away.
 * Problems:

P-40F / P-40L / Kittyhawk Mk II and Kittyhawk Mk IIa


Packard-Merlin engine, no intake on top of engine, some (all later) models were lengthened by 29", some P-40F and all P-40L had two deleted wing guns. Sometimes referred to as 'Warhawks' in DAF contexts to distinguish them from earlier Kittyhawk variants. Luftwaffe units, making note of the increased performance and longer body shape, frequently misidentified these aircraft as 'P-46'.
 * Distinguishing Features:


 * Major Operators:
 * USAAF (1943) Operation Torch, Mediterranean Theater; South-West Pacific Theater
 * VVS (100 aircraft, active in early 1943)
 * RAF (260 squadron RAF - June 1942 - May 1943)
 * Australia (3 squadron RAAF - 1942 - 1943)
 * Free French Air Force (1943) Mediterranean Theater

This version fulfilled the long-standing wish of the British to fit the P-40 with a Merlin engine (which is what ultimately led to the development of the P-51), but it arrived in combat relatively late and ironically, few of this type made it to Commonwealth units. 1311 P-40F and 700 P-40L were produced, with most being taken over by the USAAF which was then just getting into combat in Tunisia, and a few being diverted to Russia. Ultimately only ~ 330 were assigned to the Commonwealth, divided evenly between the elite 260 RAF and 3 RAAF squadrons who used them to good effect in the Med / Italy region (as Kitthawk IIa and Kittyhawk II). Only a limited number of these higher performing aircraft and their Packard Merlin engines were available though and once these were worn out or used up 260 and 3 squadrons reverted to the lower altitude Allison-engined Kittyhawk III and Kittyhawk IV.
 * Commentary:

This was however the main variant with which the USAAF faced the Luftwaffe and Regia Aeronautica in the Med during their heaviest air-to-air fighting in 1942 and 1943. The Packard Merlin engine improved performance, but the single stage, two-speed supercharger still limited the effective ceiling to about 20,000 feet. Many P-40Fs were lightened in the field by US squadrons to make them 'hot' by removing some armor and wing guns. The modest performance improvement from the Merlin engine was enough to make a difference in the Mediterranean theater and 'Warhawks' were used mostly for air superiority (escort, CAP and fighter sweep) missions, often escorting bomb laden Hurricanes or the older Kitthawk I / P-40E still in use with the DAF. When flown with proper tactics by good pilots as they frequently were in this stage of the war, the P-40F/L seemed to perform surpringly well - and most of the confirmed victories with this type were against enemy fighters, usually Me 109F/G as well as MC 202 and MC 205.

The P-40L was an official lightened version with many of the field modifications built in, nicknamed "Gypsy Rose Lee" after the famous stripper. Some had four guns, some only had two. Top speed for this type was 368 mph, essentially the same as the P-40F, but climb and acceleration were noticeably better. The F and L variants could cope with the Bf 109F and G within their effective performance ceiling and modern documentation shows that they shot down many Luftwaffe fighters. The P-40 F/L were the variants most widely used by the successful 33rd Fighter Group, 324th Fighter Group, 325th Fighter Group and 57th Fighter Groups, and also by the Tuskegee Airmen's 99th Fighter Squadron in Italy for a short time.

P-40F/L variants were supplied to Free French squadrons flying in North Africa, many of these were previously flown (and somewhat worn out) by USAAF or RAF units.

After the first 200 or so aircraft were produced, all of the later run P-40F/L types were lengthened by 29" like the later P-40N, a measure to cope with the increased torque of more powerful engines.

Though the Merlin engine increased the performance ceiling to 20,000 feet, which helped in combat, it still meant that when in combat with enemy fighters P-40F/L pilots often faced the uncomfortable prospect of being attacked from above, especially by fast flying Me 109 and MC 202 / 205 fighters. Early versions of this aircraft were slightly overpowered for the airframe making takeoff's challenging and contributing to accidents, the lengthening of the tail helped a great deal. P-40F variants as delivered were still somewhat overweight in spite of the relatively powerful engine, but this could be dealt with by stripping weight (many were lightened by ~200 lbs) and / or by overboosting the engine, which was frequently run at 60" of mercury during air combat. Greatly improved reliability of the guns meant that one pair was often removed from the plane as part of lightening efforts, sometimes two, with the result that these planes sometimes had reduced firepower.
 * Problems:

P-40N / Kittyhawk Mk IV / Warhawk


Modified rear cockpit with expanded view, lengthened fuselage, some models had two deleted wing guns
 * Distinguishing Features:


 * Major Operators:
 * USAAF: (1943–44) CBI and Pacific
 * DAF: (1943–44) Mediterranean Theater
 * RAAF: (1943–44) South West Pacific
 * RNZAF: (1943–44) South West Pacific
 * VVS: (1943 -45)
 * RCAF: (1944-45) Home War Establishment (Operational Training)

This version (Model 87V, 87W) was the most produced of all P-40s, with 5,220 examples built. It remained in use as an air superiority fighter in the CBI, and was still used in the Med as an air superiority fighter in some missions by RAF units, but it its main niche was increasingly as a fighter/bomber. The P-40N featured a lengthened fuselage and a more powerful 1300 hp Allison engine but the use of a single speed, single stage supercharger gave the model only a marginally better effective altitude than a P-40E. As with the F/L, there were both 'light' and 'heavy' versions, the lightest 'hot' fighter-configuration-with-four-guns P-40Ns achieved a top speed of up to 378 mph. The first sub-model, P-40N-1-CU, weighed only 2,700 kg (max 4,015) and it was (theoretically) meant to be a high-altitude interceptor. Climb was 6.7 minutes to 4,570 m, and it had a ceiling of 38,000 ft. Only 400 were built. Later run P-40Ns were made with a lower-power engine, specifically for training or fighter-bomber missions and had a top speed of only 345 Mph. The production led to many blocks, up to P-40N-40-CU with 1,360 hp and metal-covered ailerons. One of the most important sub-model, the P-40N-15-CU, weighed 6,200 pounds empty, 8,350 loaded, 11,400 max. Its performance dropped to 208 mph/5,000 feet, 325 mph/10,000 feet (thus almost 100 km/h slower), 343 mph/15,000 feet, at 20,000 feet in 8.8 min, service ceiling was 31,000 feet.
 * Commentary:

Initial climb rate and acceleration were dramatically improved in the lightened version of the P-40N, the only significant issue remaining was the performance ceiling, which was a little better at ~17,000 feet but still far too low. It meant that in air combat P-40N pilots (including those flying the "high altitude interceptor" subvariant), could still expect to be attacked from above. The lack of a two stage supercharger or turbo-supercharger also meant that the P-40N was limited in speed since the engine didn't perform at the higher altitudes where 400+ mph were usually achieved. At low to medium altitude it was a reasonably fast plane even by late war standards, but by the time the P-40N was introduced into combat air-to-air combat in Europe was being relegated more to high altitude bomber escort. The P-40N remained competitive in the Pacific and CBI Theaters where it mainly faced Japanese army types such as the Ki-43 'Oscar' and Ki-61 'Tony', and the IJNs old standby A6M 'Zero'.
 * Problems:

The heavier and lower-powered fighter-bomber variants of the P-40N were overweight and underpowered when fully loaded, and could be considered only 'adequate' for close air support, though they still dropped a lot of bombs in Italy through 1944 and were still used by some RAF Commonwealth squadrons in 1945. Many were used in non combat roles as trainers and so on in the US.

Specifications
Listing of specifications for early to mid-war P-40 variants.

Specifications
Listing of specifications for later P-40 variants.