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The Curtiss P-40 went through five significant transformations, comprising 10 mass-produced combat variants, in its international military service.

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

 
P-40B/C of the AVG Kunming China, piloted by Charles Older 1942
 
Soviet P-40C / Tomahawk 1942
 
Curtiss Tomahawks Mark IIBs of No. 112 Squadron RAF at LG 102 in the Sidi Heneish area, Egypt. In the foreground is AN218 'B' "Menace", flown by Flying Officer N Bowker who had shot down a Savoia Marchetti SM79 in it on 14 September 1941. The second aircraft is AK461 'A', which was destroyed in combat over Sidi Rezegh on 25 November 1941. This photograph constituted the first public appearance of 112 Squadron's famous 'Sharkmouth' insignia, when published in October 1941.
Distinguishing Features

Twin nose guns, smaller engine cowling, "long" nose

Time in Service

1941–43

Major Operators
Development

This was the original "long nose" P-40, a direct development of the moderately successful P-36 Hawk series of fighters, changed by the addition of a liquid cooled Allison V-1710 V-12 inline engine. The change conferred a 50 mph speed advantage over the already popular Hawk, and export orders from England and France came in quickly, with the United States Army Air Force also putting in domestic orders.

Operations

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 [5]. The Soviets reportedly stripped the wing guns from some of their Tomahawks to improve performance[5]..

In the Mediterranean Theater, the first Tomahawks arrived to join the Desert War with 250 Sqn RAF in June 1941. After initial teething problems were worked out, the relatively heavily armed, fast and maneuverable Tomahawk immediately started taking a heavy toll on Axis bombers, and Italian Fiat G.50 and German Bf 110 fighters. It proved sufficiently challenging of an opponent to the Bf 109E in combat that Luftwaffe pilots were soon demanding the replacement of the 'Emil' by the faster and more maneuverable 'Franz' Bf 109F[6].

On November 22, 1941 there was a significant engagement in which the Tomahawk was put to a hard test by the Bf 109F. At 1540 nine Tomahawks of No. 112 Squadron RAF were joined by thirteen Tomahawks of No. 3 Squadron RAAF for an offensive sweep over the Tobruk-El Adem area[7]. At roughly 1600 hours they were intercepted near Bir Hacheim by 20 Bf 109Fs attacking from 3,000 feet above [8]. During the subsequent hour long engagement, which took place near two German airfields, JG 27 fighters landed and refueled to rejoin the fight. In the melee DAF fighters claimed three Bf 109s shot down and four "probables", while JG 27 claimed 11 P-40s [9]. The actual losses were 6 Bf 109F-4s and 7 Tomahawk IIbs shot down and 1 badly damaged (the aircraft of future RAAF Ace Bobby Gibbes) [10]. In the aftermath of the bloody fight both sides were shaken. The Germans believed they had come out ahead but felt the losses were unacceptable , and therefore made the decision not to dogfight the Tomahawk with the Bf 109F in the future [11], and instead to rely on 'boom and zoom' tactics[12], which while effective, imposed certain Tactical limitations.

Tomahawks were used by the RAF's Army Cooperation Command from February 1941 in developing high speed, low level, tactical reconnaissance for the British Army. They were replaced in this role by the Mustang I in mid 1942.

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.

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. In a 1993 interview for the Australian War Memorial [13], Australian Ace Bobby Gibbes described the issue and the contrast between the two types:

"Some of our pilots preferred the Tomahawk, but I, mainly because those two .5s fired straight out ahead. The Kittyhawk guns came in from each side to a point, an aiming point about 150 to 200 yards ahead, and I felt the Tomahawk guns, the .5 through the prop were a better proposition."

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')

Problems

Though strongly built, the very first P-40's were poorly protected and lacked armor and self sealing tanks. This was partly 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 early 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.

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 edit

 
Restored P-40E Warbird in Aleutian "Tiger" markings.
 
A P-40E-1 piloted by the ace Keith "Bluey" Truscott, September 1942.
 
P-40E Warhawk Assigned to 1stLt. A.T. House,Jr. from the 7th Fighter Squadron, 49th Fighter Group. He was an ace with a total of 5 victories. Photo was taken right while preparing to take-off after getting an alert for enemy aircraft at Dobodura, New Guinea in May 1943.
Distinguishing Features

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

Time in Service

1941–43

Major Operators
Development

This 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 [15]) had six guns.

Operations

More powerful than the P-40B/C in terms of armor, armament and top speed, the P-40E had an Allison V-1710-39 rated at 1,150 hp for takeoff, and 1,470 hp for War Emergency Power at Sea Level (for 5 minutes)[16]. The P-40E or Kittyhawk II 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 and Java (NEI) where they were for the most part wiped out - often caught on the ground and generally outnumbered- by the formidable Japanese War Machine; and in Australia (Darwin) and New Guinea in 1942, where they were more successful (notably at Darwin and Milne Bay). Kittyhawks formed the backbone of the Desert Air Force (DAF) in intense fighting against the Luftwaffe and Regia Aeronautica also in 1942, and 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 [5]. In 1942 P-40Es began to replace older Tomahawk type (P-40 B or C) fighters in China with the AVG, equipped the 23rd Fighter Group which took over in the CBI. In this Theater they did well against JAAF aircraft such as the Ki-43 and Ki-27 fighter, and Ki-21 bomber.

The top scoring DAF squadrons, including No. 3 Squadron RAAF and No. 112 Squadron RAF, transferred from the Tomahawk to the Kittyhawk starting in Dec 1941, scoring many kills against Luftwaffe and Regia Aeronautica types, helping the DAF to hold on through this tough period. Many DAF P-40 units also took heavy casualties - especially as more Me 109F variants began to arrive in Theater in late 1941.

In a 1993 interview for the Australian War Memorial [13] Australian Ace Bobby Gibbes noted that DAF pilots were initially unimpressed with the Kittyhawk compared to the earlier Tomahawk, but noted that once they had 'improved the engine performance', the Kittyhawk was clearly superior:

"Well it was basically the same aeroplane. We were a little disappointed when we first got the Kitty, we thought it'd be way ahead of the Tomahawk. In actual fact, it was a little bit better. One thing I personally didn't like about it was the Tomahawk had fairly high sides and you'd be sitting behind a thin sheet of metal but you felt safer. The Kittyhawk had perspex coming way down and you felt as if you were sitting up, very vulnerable, because you could see out so much. That was one feature I do remember. However, later when we got our Kittyhawks running properly - were getting better performance - they were a better aeroplane."

Gibbes, who flew a captured Bf 109F and a 109G, also noted that while the Bf 109 had superior climb, ceiling and top speed, the P-40 was more maneuverable and had a better dive speed [13]:

"...its [109s] performance was quite terrific. Kittyhawk could out turn it quite comfortably and if the Messerschmitt boys came in and tried to dog fight, they were gone. We could dive away from them. If we started with same speed and they dived away, we could catch them in the dive. But with climb, they could out-climb us to blazes. Our best fighting ceiling was twelve to fifteen thousand feet, above that the Kittyhawk went off badly. The 109 was good up to thirty-odd thousand feet and so always we had them sitting up above us. Almost never would we find them on our level."

Flying with No. 75 Squadron RAAF and No. 76. Squadron RAAF, Kittyhawk Mk 1 and 1a fighters shot down raiding Japanese aircraft, sank invasion barges, and played what was called by a local ground commander "the decisive factor" [17] in the critical Battle of Milne Bay in New Guinea in 1942. Early Mark Kittyhawks also played a key role in the defense of Darwin, Australia in 1942 (where the Australian Kittyhawks were supported by American P-40s of the 49th Fighter Group), and in the battles along the Kokoda Trail. Australian units later received Kittyhawk III /P-40K and some Kittyhawk II / P-40F/L fighters which were used mostly in late 1942 and 1943, after which they were replaced by Kittyhawk IVs / P-40N. But the most critical fighting in 1942 was done by Kittyhawk Mk I and Ia.

Problems

As with all P-40's, the main problem was the effective altitude ceiling of for the D and E model, about ~ 12,000 feet. Above that altitude the single-stage Allison V-1710 engine started to perform 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. This was particularly a problem with the Australian and New Guinea Campaigns, where Japanese bombing raids were attacking from altitudes up to 27,000 feet, in part due to Australian AAA. The P-40s, with their very limited performance at that height (including climb rate which meant it took a lot longer to reach that altitude), were forced to adopt special tactics, attacking in flights of 4 planes at a time to force the A6M 'Zero' escorts to remain close to the bombers[18]. The tactics were fairly successful in spite of the challenges, with Japanese records indicating the loss of 19 Japanese aircraft destroyed for the loss of 19 P-40s [19]. In the CBI, and the North African and Russian Theaters of War, the combat altitudes were much lower, and though early model Kittyhawks were still routinely attacked from above, their performance was not hindered, to the contrary. If they could avoid or survive being bounced, they could pose a real threat, and they destroyed a large number of enemy aircraft as a result.

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 [20] and / or overboosting the engine) and suffered from problems with their 0.50 inch caliber M2 machineguns. When maneuvering in high G turns the guns would often jam due to the way the ammunition was stored [21].. 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. In his 1993 interview for the Australian War Memorial [13], Australian P-40 Ace Bobby Gibbes described the problem:

"The Kittyhawk guns you couldn't reload them. Theoretically you could, but never happened. We used to have a terrific amount of gun trouble. The armourers did a wonderful job but again sand used to get into the mechanism and there were times when you'd end without any guns shooting - firing - and in the middle of combat that wasn't much fun. Also, it was very frustrating if you had an opportunity of shooting some gent down and your guns would pack up one after the other until you had nothing to shoot with at him."

Like all early P-40 variants, P-40D and E models had some issues with takeoff swing and lateral stability requiring frequent trim setting changes when changing speed, as noted by Canadian P-40 Ace James Francis Edwards[22].

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

 
Restored P-40K Warbird in AVG markings with prominent tail fin visible
 
P-40K / Kittyhawk III with 250 RAF, operating out of LG 91 Egypt during the Battle of El Alamein, 1942
 
Three RAF P-40M / Kittyhawk III with 112 RAF operating out of Tunisia in early 1943. The extended tails of these aircraft are clearly visible.
Distinguishing Features

P-40K has expanded fin, later M models had extended tail

Time in Service

1942–44

Major Operators
  • USAAF (1942–43) New Guinea, Guadalcanal, CBI, Mediterranean and Italy (P-40K only)
  • RAAF (1942–43) Kokoda Trail, Milne Bay, Darwin (250 P-40K and 264 P-40M)
  • Royal New Zealand Air Force (RNZAF) 1942–43 South Pacific (50 P-40K and 36 P-40M)
  • RAF (1942-1944) Mediterranean, Balkans and Italy
  • Soviets - VVS (late 1942–44) PVO (1943-1945)
Development

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 for takeoff [23] and 1,550 hp for War Emergency Power (for 5 minutes) at Sea Level [24]. 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, which largely alleviated takeoff swing and required less frequent trim changes such as when performing a loop. The P-40K also featured improved machine gun ammunition storage reducing gun stoppages.

Operations

The P-40K was arguably the most important type used by the 10th Air Force and 23rd Fighter Group in the post- AVG days to establish air superiority in the China/Burma/India theater, achieving dominance over Japanese Army types in that region which was retained by P-40 squadrons until the end of the war [25]. 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 [26] who ended the war with 36 individual (22 with the P-40) and 12 shared victory claims, Leonovich Ivan Semyonovich (28 victories, most in P-40), and Denisov Konstantin Dmitrievich who scored all of his 13 individual and 6 shared victories while flying the P-40K specifically [27]. Soviet pilots such as N.G. Golodnikov noted that in 1943 the P-40 was still competitive with the Bf 109 [28]

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), P-40K pilots flying for both RAF / Commonwealth units and USAAF units such as the 57th Fighter Group nevertheless continued to score air to air victories there as well as in the CBI all the way through 1943 and into 1944. Though the preferred variant for US P-40 units in the Med was the P-40F/L, the supply of these aircraft and replacement engines for them was limited and they began to be replaced and augmented by P-40Ks starting in 1943. The same thing happened with the two Commonwealth units flying the P-40F, 260 RAF and 3 RAAF, though the former returned to the use of P-40F for several months after experiencing increased losses flying the P-40K.

Overboosting

One method used in the field to increase performance of all combat variants of the P-40 was to "over-boost" the engines to a higher manifold pressure and in some cases run them at increased RPM. Post war rumors circulated about this practice and veteran fighter pilots mentioned it in informal interviews. A Dec 12, 1942 confidential memo from Allison engine company [29] shed light on this practice and provides evidence of the routine practice of overboosting P-40s. Allison acknowledged that they had agreed to the rating of 60" Hg manifold pressure as a standard WEP setting on Allison V-1710-39 and V-1710-73, the engines in the P-40 D/E and P-40K respectively. This later became the standard WEP setting for the P-40K. Allison technicians returning from the field reported that pilots in an unnamed squadron in Australia 'admit operating for prolonged periods at around 70" Hg of boost' which they estimated would produce 1780 hp near Sea Level [29]. Another squadron in the Middle East was resetting boost controls to 66" Hg, estimated to produce 1770 hp at 2,000 feet [29] at 3200 R.P.M. Allison advised the War Department that such practices could cause engine failure in the later generation (V-1710 - 83,-85 and 81) engines with a higher 9.6:1 supercharger gear ratio. The memo also noted that overboosting was safer with higher quality "Amendment 5 fuel"[29]

Australian Ace Bobby Gibbes described an incident[13] in which he was able to take advantage of extra power from a Kittyhawk III to shoot down a Bf 109 out of a formation of three planes which were passing over his squadron. Gibbes noted that this Kittyhawk III was faster than the Merlin powered Kittyhawk IIs he was flying with:

"Well I was a poor shot. Air to ground I think I was a very good shot. I could group my bullets and make sure they didn't run through. I could hold them on target while I went in and strafed. But air to air I certainly missed an awful lot of aeroplanes I fired at. I think the classic example was one day when I had a Kitty Mark III - I had acquired it illegally, I might say - and I had to give it back to the RAF later - but I had a little bit more horsepower than the rest of the squadron and when three 109s passed overhead or ahead of us, if I had waited to take the squadron with me, which normally I would have done, they would have got away.
But seeing them and knowing I had that bit more power I opened the taps and went after them. I had a look at the three of them and I thought, if I pull a lead on the number one, number three could probably get a deflection shot at me, so I thought, well, I'll get number two first. So I fired at number two. I must have misjudged their speed completely because the one behind, probably fifty yards behind, flicked over and went down smoking like hell. I looked round to see who else had shot at it but I was the only one in the sky. I then decided, well, I'll go after the number one and number two but, of course, they didn't wait for me. The one, incidentally, number three, did go in.
Yes, it was a successful mission. We had a big celebration that night in the squadron and a few of the 'Yanks' came over and they thought the shooting was quite brilliant and I had only fired very few rounds. However, during the night I managed to get quite a few grogs on board and I decided that I'd confess that I hadn't even aimed at that one, I'd aimed at the one ahead of it. And, of course, when I did tell them of course no one believed me, but it was true."
P-40M

The P-40M was supposed to be a purely export variant of the K though some ended up in USAAF units. Though the V-1710-81 engine on the P-40M was rated much lower (1,360 hp for WEP, 1,200 hp for takeoff [30]) than the V-1710-73 on the P-40K the -81 had slightly better power at altitude (1,125 at 15,500 ft for the M vs the same power at 12,000 ft for the K). P-40M were, like the K designated as Kittyhawk III in Commonwealth service, which can make them hard to distinguish from the P-40K (especially late model P-40K with the extended tail). 264 were delivered to the RAF, 168 to Australia, and 34 to New Zealand. Most of the RAF aircraft were operated in the Med.

Problems

The main problems remaining were the effective performance ceiling of 12 - 15,500 ft. Secondary issues included the takeoff swing and torque caused by 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.

Canadian Ace James "Stocky" Edwards noted that most of the stability and engine management problems he experienced with the earlier Marks of Kittyhawk were resolved in the Kittyhawk MK II and III:

"The Kittyhawk Mk II (P-40F) with Packard-Merlin engine - the Americans called it the Warhawk, but in 260 Squadron we called it the 'Gosh-Hawk'- was a definite improvement in lateral stability over the Mk. I. 260 Squadron flew Kittyhawk IIs from September 1942 to December 1942, and we received Kittyhawk IIIs with many modifications and improvements added by the end of the Tunisian campaign. Eventually with the Mk III, the Kittyhawk became a good stable fighting aircraft, though it never did have enough power or climbing ability compared to a 109 or a Spitfire."[31]

Edwards also noted that the P-40 could turn inside the Bf 109, though not as easily as the Spitfire, and that the Mk III was fast, with a cruising speed comparable to a Spitfire Mk IX, while the Mk II had a cruising speed comparable to a Spitfire Mk V. [32].

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

 
Restored P-40F Warhawk "Lee's Hope" Warbird in 79th FG colors with lengthened fuselage and clean upper cowling clearly visible
 
P-40L in Tunisia 99th FS (Tuskegee) 1943
 
P-40F or L over Texas 1943
 
P-40Fs of the 44th Fighter Squadron USAAF, Guadalcanal


Distinguishing Features

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'.

Time in Service

1942–44

Major Operators
Development;

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. The Packard Merlin engine improved performance, but the single stage, two-speed supercharger still limited the effective ceiling to about 20,000 feet. The engine used was not the famous Merlin 60 series used in the P-51 and Spitfire MK IX with a two stage blower, but rather it was a variant of the earlier Merlin XX used by the Hawker Hurricane II and Spitfire MK V. The decision to use the single-stage supercharger version, (the Packard V-1650-1, known to the British as the Merlin 28) which had much less power and altitude capability than the Merlin 60, was part of what triggered P-40 designer Don R. Berlin to leave Curtiss aircraft company [34]. As a result, while performance at altitude was improved it was only increased by 5,000 feet. Many P-40Fs were lightened in the field by US squadrons to make them 'hot' by removing some armor and wing guns, and the P-40L was built with less armor and some fuel tanks removed, but even the F variant of the P-40 suffered from limited altitude capability, which was a source of immense frustration to the War Department and pilots and commanders in the field.

Operations

Ultimately only ~ 250 merlin engined were assigned to the Commonwealth (150 P-40F and 100 P-40L [35]), divided evenly between the elite 260 RAF and 3 RAAF [36] squadrons. The RAF who jokingly referred to this variant as the "gosh-hawk", used them to good effect in the Med / Italy region (as Kitthawk IIa and Kittyhawk II) with 6500 sorties flown and 60 enemy aircraft claimed between June 1942 and March 1944 [37]. 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.

This was however the main variant with which the five USAAF fighter groups in the Theater faced the Luftwaffe and Regia Aeronautica during the heaviest air-to-air fighting in 1942 and 1943.

The modest performance improvement from the Merlin engine, most significantly the increased performance ceiling of 20,000 feet, was enough to make a difference in the Mediterranean theater and merlin-engined 'Warhawks' were used mostly for air superiority (escort, CAP and fighter sweep) missions, often escorting bomb laden Hurricanes or the older Kittyhawk 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 surprisingly well. For example while using the Kittyhawk II and IIa 260 Squadron RAF claimed 32 confirmed victories - including 20 Bf 109 and 6 MC 202- for 19 operational losses to all causes. [38]. Lt Richard T Conly of the 315th FS / 324th FG emphasized his appreciation of the strengths of the P-40F when he described an April 29 1943 encounter over Tunisia in which he scored his first confirmed victory:

'When I pulled back up, I had just climbed to about 7000 ft when another '202 jumped me at nine o'clock high. I turned into him, and he started turning to get on my tail. At this point I really swore by a P-40, because I could dogfight and out turn him with ease. He saw I was going to get a shot and headed for the deck, strait down. I never got farther than 100 yards behind him, and he stayed right in my sights. I watched my tracers pound into him all the way. Those good old six "fifties" raked him from the tail up. He hit the deck about 50 ft just offshore and went strait in. I almost got wet in the splash." [39]

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, and the RAF considered the type to be more stable than the F [40], (possibly because all of the P-40L were lengthened whereas only about half of the F model were). 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. For example while flying P-40F/L, between May and September of 1943 pilots of the 325th Fighter group claimed 102 victories in 37 missions, for the loss of just 16 aircraft [41]. Four pilots from the group made Ace during this period, mostly while flying missions over Sardania [42]. The P-40 F/L were the variants most widely used by the successful 33rd Fighter Group, 324th Fighter Group[43], 325th Fighter Group, 79th Fighter Group [44], [45] and 57th Fighter Group[46], 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.

Problems

Though the Merlin engine increased the performance ceiling to 20,000 feet, which helped in combat, P-40F/L pilots still sometimes faced the uncomfortable prospect of being attacked from above by high flying Me 109 and MC 202 / 205 fighters. Early versions of the P-40F were slightly overpowered for the airframe making takeoff's challenging and contributing to accidents; the lengthening of the tail helped a great deal [47]. 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 (+15 lbs by RAF measure) during air combat. Greatly improved reliability of the guns meant that one pair could be removed from the plane as part of lightening efforts, sometimes two, with the result that some planes sometimes had reduced firepower.

Though lightened P-40L had slightly better performance than the P-40F, the removal of two of the wing fuel tanks caused a reduction in effective range which affected flight operations notably in the invasion of Sicily and during the campaign over the Anzio beachhead. As Axis fighters became rarer on the Mediterranean battlefields, wing guns were added back in so that by 1944, most surviving P-40L were flying with 6 guns. The extra firepower was useful for strafing. Similarly in the Pacific Theater almost all P-40F&L used by US and Australian squadrons had 6 guns.

P-40N / Kittyhawk Mk IV / Warhawk edit

 
Warbird in 1944 Pacific Theater markings.
 
Restored Curtiss P-40N-5-CU Warbird.
 
Wartime P-40N with external fuel tank, in a nearly identical shot.
 
The Curtiss P-40P-40N Kittyhawk, "Black Magic", flown by Warrant Officer Len Waters, the first Australian Aboriginal military pilot, with No. 78 Squadron RAAF, in the Dutch East Indies, 1944-45.
Distinguishing Features

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

Major Operators
  • USAAF: (1943–45) CBI and Pacific
  • DAF: (1943–45) Mediterranean Theater (mostly Italy)
  • RAAF: (1943–44) South West Pacific
  • RNZAF: (1943–44) South West Pacific
  • Soviets, VVS: (1943), PVO (1943-1945)
  • RCAF: (1944-45) Home War Establishment (Operational Training)
Development

This version (Model 87V, 87W) was the most produced of all P-40s, with 5,220 examples built [48]). 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.

Some later block 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.

Operations

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 than older variants 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 available 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 starter was removed from the original lightened P-40N-1 version requiring an external starter for takeoff. Some pilots observed that this in effect meant that squadrons took much longer to take off since the starter had to be moved from plane to plane [49]. The battery and internal starter was soon replaced in subsequent blocks [50].

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: Early P-40 Models edit

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

P-40B P-40E-1 P-40K-15
General characteristics
Crew One One One
Length 31 ft 8 in (9.66 m) 31 ft 8 in (9.66 m) 31 feet 2 in
Wingspan 37 ft 4 in (11.38 m) 37 ft 4 in (11.38 m) 37 ft 4 in (11.38 m)
Height 12 ft 4 in (3.76 m) 12 ft 4 in (3.76 m) 12 ft 4 in (3.76 m)
Wing area 235.94 ft² (21.92 m²) 235.94 ft² (21.92 m²) 235.94 ft² (21.92 m²)
Empty weight 5,590 lb (2,535 kg) 6,350 lb (2,880 kg) 6,350 lb (2,880 kg)
Loaded weight 7,326 lb (3,323 kg) 8,280 lb (3,760 kg) 8,280 lb (3,760 kg)
Maximum gross takeoff weight 7,600 lb (3,447 kg) 9,200 lb 10,810 lb (4,535.9 kg)
Powerplant 1x Allison V-1710-33 1x Allison V-1710-39 1x Allison V-1710-73
Power rating - WEP 1,040 hp 1,470 hp 56" Hg @ SL (5 Min) [51] 1,550 hp 60" Hg @ SL (5 Min)[52]
Power rating - Takeoff 1,040 hp 1,150 hp 45.5" Hg at Sea Level (5 Min) 1,325 hp 51" Hg at SL (5 Min) [53]
Power rating - Military 1,040 hp @ 14,300 ft [54] 1,150 hp 42" Hg @ 12,000 ft (5 Min) [55]</ref> 1,150 with 42" Hg at 12,000 ft (15 Min) [56]
Performance
Maximum speed 352 mph (566 km/h) 360 mph (580 km/h) 362 mph at 15,000 ft
Cruise speed n.a. 258 mph (435 km/h) 290 mph [57]
Range 730-1230 mi (1,173-1,977 km) 650 mi (1,050 km) 700 mi (1,050 km)[58]
Service ceiling 32,400 ft (9,875 m) 29,000 ft (8,840 m) 32,500 ft
Climb rate 2,860 ft/min (14.5 m/s) 2,580 ft/min (10.7 m/s)[59] 2,210 ft/min  ft/min (16.38 m/s)
Wing loading 31 lb/ft² 152.3 kg/m² 35.1 lb/ft² (171.5 kg/m²) 35.6 lb/ft² (176 kg/m²)[60]
Power/mass 0.16 hp/lb 0.14 hp/lb (230 W/kg) - 0.17 at WEP 0.16 hp/lb (260 W/kg) - 0.18 at WEP
Armament
  • 2x .50 cal (12.7 mm) and 4x .30 cal Browning
  • 6x .50 cal (12.7 mm) Browning M2 machine guns, 281 rounds/gun
  • Up to 1,500 lb (680 kg) of bombs on three hardpoints.
  • 6x .50 cal (12.7 mm) Browning M2 machine guns, 281 rounds/gun
  • Up to 1,500 lb (680 kg) of bombs on three hardpoints.

Specifications: Later P40 Models edit

 
P-40Fs being handed over to Free French Squadron GC II-5 on 9 Jan, 1943.

Listing of specifications for later P-40 variants.

P-40F-5-CU P-40L-10 P-40N-1 (Interceptor version)
General characteristics
Crew One One One
Length 33 feet 4 in (11,38 m) 33 ft 4 in (10.16 m) 33 ft 4 in (10.16 m)
Wingspan 37 ft 4 in (11.38 m) 37 ft 4 in (11.38 m) 37 ft 4 in (11.38 m)
Height 12 ft 4 in (3.76 m) 12 ft 4 in (3.76 m) 12 ft 4 in (3.76 m)
Wing area 235.94 ft² (21.92 m²) 235.94 ft² (21.92 m²) 235.94 ft² (21.92 m²)
Empty weight 6,590 lb (2,989 kg) [61] 6,340 lb (2,875 kg)[62] 6,000 lb (2,905 kg)[63]
Loaded weight 8,480 lb (3,846.4 kg) 8,020 lb (3,505 kg) 7,730 lb (3,505 kg)
Maximum gross takeoff weight 9,350 lb (4,238 kg) 8,950 lb (4,238 kg) 8,860 lb (4,020 kg)
Powerplant Packard-Merlin V-1650-1 (Merlin 28) Packard-Merlin V-1650-1 (Merlin 28) Allison V-1710-115
Power rating - WEP 1,435 hp (5 min) 1,435 hp (5 min) 1,360 hp (5 min) 57" Hg @ SL [64]
Power rating - Takeoff 1,300 hp 54" Hg [65] 1,300 hp [65] 1,200 hp 51" Hg at SL [66]
Power rating - Military 1,240 hp @ 11,800 ft [67] or 1,120 hp at 18,500 ft 1,240 hp at 11,800 ft [68] or 1,120 hp at 18,500 ft 1,125 with 44.5" Hg at 15,500 ft (15 Min) [69]
Performance
Maximum speed 364 mph at 19,900 ft (585 km/h) [70] 370 mph at 20,400  (595 kph) [71][72] 378 mph (608 km/h) at 5,000 m (16,400 ft)
Cruise speed 302 mph (482 kph)[73] 295 mph [74] 288 mph (455 km/h)[75]
Range 700-1500 mi with drop tank (1k125-2,400 km) 653 miles [76] 745 mi (1,200 km)
Service ceiling 34,400 ft (10,500 m) 34,400 ft (10,500 m) [77] 38,000 ft [78]
Climb rate 2,000 ft/min @ military power or 3,220 ft/min @ WEP 3,300  ft/min [79] @ WEP 2,300 ft/min @ Military power 3,520 ft/min @ WEP
Wing loading 35.2 lb / ft ² 33.9 lb/ft² 31.36 lb/ft² (159.9 kg/m²) [80]
Power/mass 0.15 hp/lb (245 W/kg) - 0.16 at WEP 0.16 hp/lb - 0.18 at WEP 0.16 hp/lb (260 W/kg) - 0.17 at WEP
Armament
  • 4 or 6x .50 cal (12.7 mm) M2 machine guns, 240-312 rounds/gun
  • 2x 227 kg bomb
  • 4x .50 cal (12.7 mm) M2 machine guns, 201 rounds/gun
  • 2x 227 kg bomb
  • 4x .50 cal (12.7 mm) Browning M2 machine guns
  • Up to 1,500 lb (680 kg) of bombs on three hardpoints.

References edit

Notes
  1. ^ Rossi, J. R. "History." AVG: American Volunteer Group, The Flying Tigers, 1998. Retrieved: 5 July 2011.
  2. ^ Jordan, Corey C. (1998–2000). "The Amazing George Welch: Part One - The Tiger of Pearl Harbor". Planes and Pilots Of World War Two. Archived from the original on 15 October 2015.
  3. ^ L, Klemen (1999–2000). "Chronology of the Dutch East Indies, 7 December 1941 – 11 December 1941". Forgotten Campaign: The Dutch East Indies Campaign 1941–1942. Archived from the original on 15 October 2015.
  4. ^ L, Klemen (1999–2000). "The conquest of Java Island, March 1942". Forgotten Campaign: The Dutch East Indies Campaign 1941–1942. Archived from the original on 26 July 2011.
  5. ^ a b c Romanenko, Valeriy and James F. Gebhardt. "The P-40 in Soviet Aviation." Lend-lease on airforce.ru. Retrieved: 7 March 2006.
  6. ^ Shores, 2012, P.216
  7. ^ Shores 2012, P.331
  8. ^ Shores 2012, P.331
  9. ^ Shores 2012, P.329
  10. ^ Shores 2012, P.331
  11. ^ Shores 2012, P.329
  12. ^ Shores 2012, P.329
  13. ^ a b c d e Interview with Bobby Gibbes. "Interview with Bobby Gibbes." 3 Squadron RESEARCH. Retrieved: 11 June 2018.
  14. ^ Demin, Anatolii (2000). "Changing from "Donkeys" to "Mustangs" Chinese Aviation In The War With Japan, 1940–1945". Planes and Pilots Of World War Two.
  15. ^ Baugher, Joe. "Curtiss P-40 Warhawk, Tomahawk, Kittyhawk." American Military Aircraft.
  16. ^ Shamburger, 1972, p. 231
  17. ^ Gillison (1962), p. 617
  18. ^ Weston, Brian. "The USAAF 49th Fighter Group over Darwin: a forgotten campaign" Australian Strategic Polity Institute.
  19. ^ Weston, Brian. "The USAAF 49th Fighter Group over Darwin: a forgotten campaign" Australian Strategic Polity Institute.
  20. ^ Baugher, Joe. "Curtiss P-40 Warhawk, Tomahawk, Kittyhawk." American Military Aircraft.
  21. ^ Shores 2014, p. 22.
  22. ^ Shores 2014, pp. 21, 22.
  23. ^ Molesworth 2013, p. 26.
  24. ^ Shamburger, 1972, P. 231
  25. ^ Molesworth 2000, p. 6
  26. ^ Mellinger 2006, pp. 37,52, .
  27. ^ List of Soviet Fighter Aces. "Soviet Fighter Aces." War is Over. Retrieved: 14 May 2014.
  28. ^ Drabkin 2007, p. 130.
  29. ^ a b c d Allison 1710-39 abuse.pdf. "Allison Engine Memo." WWII Aircraft Performance.org. Retrieved: June 15 2018.
  30. ^ Shamburger 1973, P.231)
  31. ^ Shores 2014, pp. 21, 22.
  32. ^ Shores 2014, p. 22.
  33. ^ "Curtiss P-40E, K, M, N Warhawk/Kittyhawk." Archived 6 January 2011 at the Wayback Machine Air Force Museum of New Zealand. Retrieved: 5 July 2011.
  34. ^ Christy, Joe. "Hawkman: An Exclusive Interview with Dr. Donovan Reese Berlin." Wings, Volume 3, No. 1, February 1973, page 21.
  35. ^ Listemann 2017, p. 3.
  36. ^ Listemann 2017, p. 4.
  37. ^ Listemann 2017, pp. 4-5.
  38. ^ Listemann 2017, pp. 28-29.
  39. ^ Molesworth, 2002, P.65
  40. ^ Listemann 2017, p. 4.
  41. ^ Molesworth 2103, p 58
  42. ^ Molesworth 2103, p 58
  43. ^ Shores 2016, p. 422.
  44. ^ Worpel 2001, p. 57.
  45. ^ Shores 2016, p. 423.
  46. ^ Shores 2016, p. 422.
  47. ^ Molesworth 2013, p. 15.
  48. ^ Molesworth 2013, p. 16.
  49. ^ Molesworth 2013, p. 16.
  50. ^ Molesworth 2013, p. 16.
  51. ^ Shamburger 1972, P.231
  52. ^ Shamburger 1972, p. 231
  53. ^ Shamburger 1972, p. 231
  54. ^ Shamburger 1972, P.231
  55. ^ Shamburger 1972, P. 231
  56. ^ Shamburger 1972, p .231
  57. ^ Molesworth 2013, p. 22.
  58. ^ Molesworth 2013, p. 25.
  59. ^ Molesworth 2013, p. 22.
  60. ^ Molesworth 2013, p. 25.
  61. ^ El Beid 2008, p.34
  62. ^ Shamburger 1972, p.234
  63. ^ Molesworth 2013, p. 31.
  64. ^ Shamburger 1972, p .231
  65. ^ a b "Packard V-1650-1" WWII Aircraft Performance Retrieved: 12 June 2018
  66. ^ Shamburger 1972, p .231
  67. ^ Molesworth, 2013, P.23
  68. ^ Molesworth, 2013, P.23
  69. ^ Shamburger 1972, p .231
  70. ^ Shamburger 1972, page 234
  71. ^ "Performance figures for Kitthyawk II, British Air Commission 9.9.42." Retrieved: 20 February 2018.
  72. ^ El Beid 2008, p.51
  73. ^ El Beid 2008, p.34
  74. ^ Shamburger, 1972
  75. ^ Molesworth 2013, p. 34.
  76. ^ El Beid 2008, p.51
  77. ^ Molesworth 2013, p.27
  78. ^ Molesworth 2013, p. 16.
  79. ^ Shamburger 1972, p.234
  80. ^ Molesworth 2013, p. 32.
Bibliography
  • Baugher, Joe. "Curtiss P-40 Warhawk, Tomahawk, Kittyhawk." American Military Aircraft.
  • War Planes of the Second World War, Fighters, Volume Four, William Green, Doubleday, 1964.
  • The American Fighter, Enzo Angelucci and Peter Bowers, Orion Books, 1987.
  • United States Military Aircraft since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian Institution Press, 1989.
  • Curtiss Aircraft, 1907-1947, Peter M. Bowers, Naval Institute Press, 1979.
  • The Curtiss P-40 Tomahawk, Ray Wagner, Aircraft in Profile, Volume 2, Doubleday, 1965.
  • Shores, Christopher et al, A History of the Mediterranean Air War, Volume 2, Grub Street, 2014.
  • Shores, Christopher et al, A History of the Mediterranean Air War, Volume 3, Grub Street, 2016.
  • Shores, Christopher et al, A History of the Mediterranean Air War, Volume 1, Casemate, 2012.
  • Worpel, Don, The 79th Fighter Group over Tunisia, Sicily and Italy in World War II, Schiffer Military History, 2001
  • Shores, Christopher, Bloody Shambles, Vol2, 2008.
  • Bf 109 Aces of North Africa and the Medtierranean, Osprey, 1997.
  • Brown, Russel, Desert Warriors, Banner Books, 2007.
  • Molesworth, Carl. P-40 Warhawk Aces of the MTO (Osprey Aircraft of the Aces No. 43). London: Osprey Publishing, 2002. ISBN 1-84176-288-1.
  • Molesworth, Carl. P-40 Warhawk Aces of the Pacific (Aircraft of the Aces). London: Osprey Publishing, 2003. ISBN 1-84176-536-8.
  • Molesworth, Carl. P-40 Warhawk Aces of the CBI(Osprey Aircraft of the Aces No. 35). Oxford, UK: Osprey Publishing, 2000. ISBN 1-84176-079-X.
  • Molesworth, Carl. P-40 Warhawk vs Ki-43 Oscar: China 1944–45. Oxford, UK: Osprey Publishing, 2008. ISBN 1-84603-295-4.
  • Molesworth, Carl. Curtiss P-40, snub nosed Kittyhawks and Warhawks (Osprey Air Vanguard 11). Oxford, UK: Osprey Publishing 2013. ISBN 978-1780969121.
  • Mellinger, George. P-40 Soviet Lend-Lease Fighter Aces of World War 2 (Aircraft of the Aces No. 74). Oxford, UL: Osprey Publishing, 2006. ISBN 1-84603-041-2.
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  • P-40 Warhawk in Action, Signal, 2007
  • Listemann, Phil, The Curtiss Kittyhawk Mk II Squadrons! No. 18, Philedition, 2017. ISBN 979-1096490042.
  • Drabkin, Artem. The Red Air Force at War: Barbarossa and the Retreat to Moscow – Recollections of Fighter Pilots on the Eastern Front. Barnsley, South Yorkshire, UK: Pen & Sword Military, 2007. ISBN 1-84415-563-3.
  • Gillison, Douglas (1962). Royal Australian Air Force 1939–1942. Australia in the War of 1939–1945. Series 3 – Air. Vol. Volume 1. Canberra: Australian War Memorial. OCLC 2000369. {{cite book}}: |volume= has extra text (help)
  • El Beid, Anis & Laurelut, Daniel. Curtiss P-40 from 1939 to 1945 (Planes and Pilots 3), Histoire and Collections, 2008. ISBN 2-913903-47-9.
  • Shamburger, Page & Christy, Joe. The Curtiss Hawks. Wolverine Press, 1972. Library of Congress No. 79-173429
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