The Curtiss P-40 Warhawk was derived from the radial-engine P-36 Hawk, modified to incorporate the inline Allison V-1710 engine.
First flown in 1938, it entered service in 1939.
Despite its limitations at high altitude, the P-40 was rugged, reliable, and easy to maintain.
A total of 13,738 units were produced between 1939 and 1944, making it one of the most widely built American fighters of the war.
Naming Conventions
Warhawk
Official USAAF designation for all variants post-1941.
Tomahawk
British Commonwealth name for early variants (P-40B/C).
Kittyhawk
Used for later variants (P-40D and beyond).
Combat Deployment by Theater
North Africa and the Middle East
First combat use by RAF No. 112 Squadron in mid-1941.
Known for the distinctive shark-mouth nose art.
Provided air cover, bomber escort, and ground attack in desert conditions.
Operated by USAAF, RAF, RAAF, and South African Air Force units.
China-Burma-India (CBI) Theater
Famously flown by the American Volunteer Group (AVG), the Flying Tigers.
Excelled in low-altitude ambush tactics against Japanese fighters.
Continued service under the USAAF after AVG disbanded in 1942.
South-west Pacific
Used by USAAF and RAAF in New Guinea, the Philippines, and the Dutch East Indies.
Provided close air support, bomber escort, and airfield defence.
Effective against Japanese aircraft at low-to-medium altitudes.
Soviet Eastern Front
Supplied under Lend-Lease; used primarily in ground attack and air defense roles.
Operated in secondary sectors due to performance limitations.
Italian Campaign and Mediterranean
Used by USAAF and Allied forces for tactical support and convoy protection.
Gradually replaced by more advanced types by late 1944.
Alaska and Aleutians
Deployed for air defence and patrol missions in harsh Arctic conditions.
Operated by USAAF units during Japanese incursions into the Aleutians.
Strengths and Limitations
Strengths
Durable construction, good firepower, effective at low altitude, widely available.
Limitations
Poor high-altitude performance, limited climb rate, and outclassed by newer fighters by 1943.
Legacy
The P-40 was not a technological marvel, but it was available when needed most.
It served as a frontline fighter during the critical early years of the war and remained in service in secondary roles until 1945.
Its iconic shark-mouth livery and association with the Flying Tigers cemented its place in aviation history.
The Variants
Curtiss XP-40 – Prototype
The Allison-Powered Model 75
The XP-40 was developed by modifying the tenth P-36A airframe, replacing its radial engine with the liquid-cooled Allison V-1710-19 V-12.
This streamlined the nose and improved aerodynamics.
First flown on 14 October 1938, it reached 342 mph at 12,200 ft—respectable for its time.
Though not revolutionary, the XP-40 offered a fast path to production.
Its evolutionary design allowed Curtiss to quickly deliver a capable fighter, leading directly to the mass-produced P-40 series used widely in WWII.
P-40 (Model 81A) – Early Production Overview
The initial production P-40 (Model 81A) closely followed the XP-40 prototype but featured a 1,040 hp V-1710-33 engine and one. 30 cal M1919 Browning in each wing.
Curtiss redesignated it as Model 81 due to significant changes from the earlier Model 75.
France ordered 140 units as Hawk 81A-1s, but after the 1940 armistice, these were diverted to the RAF and redesignated Tomahawk Mk. I.
Lacking armour and heavy armament, they were not combat-ready but were deployed in North Africa due to aircraft shortages post-Battle of Britain.
Sub-Variants
P-40
P-40A
P-40G
Hawk 81A-1
(Tomahawk Mk.I)
P-40
524 ordered; 200 built.
P-40A
Single unit modified for photo reconnaissance.
P-40G
44 aircraft were retrofitted with four-gun P-40B/C wings; the first unit was informally called the XP-40G.
Hawk 81A-1
Export version for France, delivered to the RAF as the Tomahawk Mk. I.
P-40B
Of the 324 aircraft from the initial order, 131 were constructed as P-40Bs.
While robustly designed, the initial variant of the P-40 suffered from inadequate protection, lacking both armour and self-sealing fuel tanks.
This issue was somewhat addressed in the P-40B, which featured extra armour behind the cockpit; however, vulnerabilities in the fuel system and control lines persisted across all Tomahawk variants.
Additionally, the P-40B was equipped with an extra .30-calibre machine gun in each wing.
Hawk 81A-2
This export variant saw the production of 110 aircraft for the RAF, designated as Tomahawk Mk.IIs and Mk.IIAs, with the latter fitted with .303 Browning machine guns.
P-40C
The final 193 aircraft from the original P-40 order were completed as P-40Cs.
To improve survivability, they featured self-sealing fuel tanks and replaced the outdated SCR-283 radio with the SCR-274N.
A 52-gallon drop tank was added, significantly extending combat range—a feature adopted in all later P-40 variants.
Hawk 81A-3 Export model
930 was built for the RAF as the Tomahawk Mk. IIB, many reallocated.
Hawk 81A-2/3
100 diverted to China for the AVG; lacked drop tank fittings.
Curtiss P-40D
Warhawk (U.S.), Kittyhawk Mk I (RAF)
Key Features
First major redesign of the P-40 series, transitioning from the P-40B/C (Model 81) to the more powerful Model 87.
Equipped with the Allison V-1710-39 inline engine (1,150 hp), improving speed and climb rate.
The armament was upgraded to four .50 calibre wing-mounted machine guns, eliminating nose guns.
Shortened nose profile and deeper radiator scoop for better aerodynamics and cooling.
Operational Notes
Only 22 P-40Ds were built before production shifted to the D-1 variant.
Served primarily in training and early deployment roles; few saw combat.
The RAF received these under Lend-Lease as Kittyhawk Mk I, though some were retained by the USAAF.
Curtiss P-40D-1
Warhawk (U.S.), Kittyhawk Mk IA (RAF)
Key Features
Nearly identical to the P-40D but included provisions for belly-mounted external fuel tanks or bombs.
Slight structural reinforcements to accommodate ordnance loads.
Continued use of the Allison V-1710-39 engine and four wing-mounted .50 cal guns.
Operational Notes
Approximately 560 units produced.
Widely exported to Commonwealth forces, especially the RAF and RAAF.
Designated Kittyhawk Mk IA in British service, it was often used in North Africa and the Pacific.
Hawk 87A-1 (company export name), Kittyhawk Mk I (RAF)
Key Features
Essentially identical to the P-40D, but built for foreign customers under Curtiss’s internal export designation.
Featured British instrumentation and radios, tailored to RAF specifications.
Retained the same engine and armament as the P-40D.
Operational Notes
Delivered to the RAF under the Kittyhawk Mk I designation.
Used by squadrons in the Middle East, North Africa, and Australia.
Often confused with the P-40D due to shared airframe and performance characteristics.
Prototype P-40E
Designation
Developmental precursor to the P-40E; not a formal variant but a transitional configuration.
Origin
Evolved from the P-40D, incorporating a more powerful Allison V-1710-39 engine.
Armament
Introduced six .50 cal wing-mounted machine guns (three per wing), replacing the four-gun layout of the P-40D.
Purpose
Served as the testbed for refining the P-40E’s combat configuration, especially for air-to-air roles.
Notes
This prototype helped solidify the P-40E’s role as the backbone of early 1942 Allied fighter operations.
P-40E (Model 87A-1 / Kittyhawk Mk IA)
Production
One of the most widely produced P-40 variants.
Engine
Allison V-1710-39, liquid-cooled V-12.
Armament
Six .50 cal Browning M2 machine guns; underwing bomb shackles added on some units.
Operational Use
USAAF
Replaced AVG (Flying Tigers) P-40B/C aircraft in China.
RAAF & RNZAF
Used extensively in the Pacific, notably at Milne Bay and Guadalcanal.
RAF/Commonwealth
Designated Kittyhawk Mk IA; saw action in North Africa.
Significance
Represented the peak of P-40 air combat capability before high-altitude performance upgrades.
P-40ES
Designation
Experimental or special modification of the P-40E; not a widely documented production variant.
Purpose
Involved in trials at NACA related to two seat conversions.
Status
No production; Served as a Testbed only.
Notes
Often confused with field-modified P-40Es or misidentified in postwar documentation
P-40EF
During World War II, the Soviet Air Force (VVS) received over 2,000 Curtiss P-40 fighters—including E and K variants—through Lend-Lease agreements.
While primarily used in frontline fighter roles, a small number of these aircraft were locally modified for tactical photo reconnaissance duties.
At the 1st Aircraft Repair Base of the Leningrad Front, Soviet technicians converted a limited batch of P-40Ks (and likely some P-40Es) into two-seat reconnaissance platforms.
The designation “P-40EF” was unofficial and locally applied by Soviet personnel.
The “F” stood for “Foto”—the Russian word for photo—indicating its reconnaissance role.
These aircraft were used primarily for tactical battlefield photography, especially in support of operations around Leningrad and other northern sectors.
Hawk 87A-2
Company Designation
Curtiss Model 87A-2.
Export Role
Supplied to Allied nations under Lend-Lease; often designated as Kittyhawk Mk IA or Mk II depending on configuration.
Configuration
Based on the P-40E airframe, with minor equipment or instrumentation changes for export.
Operators
RAF, RAAF, RNZAF, and other Commonwealth air forces.
Significance
Played a crucial role in desert air combat and Pacific defence; often confused with domestic P-40E due to similar structure.
XP-40F
Role
Prototype conversion of the P-40D.
Engine
British-built Rolls-Royce Merlin 28, 1,300 hp.
Purpose
Tested to improve high-altitude performance over the Allison-powered P-40E.
First flight
25 November 1941.
Outcome
Led directly to the production of the P-40F series with Packard-built Merlin’s.
P-40F / P-40F-1
Production
First major batch—699 aircraft.
Engine
Packard V-1650-1 (licensed Merlin), 1,300 hp.
Design
Initially retained the short fuselage of the P-40E.
Issues
Directional instability due to torque from the Merlin engine.
Fix
Later blocks (starting with P-40F-5) received extended fuselages
P-40F-5
Quantity
123 built.
Modification
Fuselage lengthened by ~1 meter (to 33 ft 4 in).
Reason
Counteract torque and improve directional stability.
Visual cue
Rudder moved aft of the tailplane—distinctive silhouette change
P-40F-10
Quantity
177 built.
Change
Replaced electric cowl flap actuators with manual systems.
Rationale
Improve reliability in field conditions and reduce electrical load.
P-40F-15
Quantity
200 built.
Feature
Winterization package.
Details
Included cold-weather lubricants, cockpit insulation, and engine pre-heaters for operations in northern Europe and Russia.
P-40F-20
Quantity
112 built.
Upgrade
Revised oxygen delivery system.
Purpose
Enhance pilot endurance and safety at high altitudes.
YP-40F
Role
Third production P-40F used for aerodynamic testing.
Focus
Streamlining and performance optimization.
Status
Experimental—did not enter mass production.
P-40R-1
Conversion
At least 70 P-40Fs retrofitted with Allison V-1710-81 engines.
Reason
Shortage of Merlin engines.
Performance
Slightly reduced high-altitude capability compared to Merlin-powered versions.
Designation
“R” for “Re engined.”
Hawk 87B-2 (Kittyhawk Mk.II)
Export
150 aircraft built for the RAF under Lend-Lease.
Designation
Known as Kittyhawk Mk.II in British service.
Engine
Packard Merlin V-1650-1.
Deployment
Used in North Africa and the Mediterranean.
Operators
RAF, RAAF, SAAF—though not all reached their intended recipients due to convoy losses
P-40K-1
Originally part of a 600-aircraft order intended for China, the P-40K-1 subvariant was redirected following the Japanese attack on Pearl Harbor.
These aircraft were instead absorbed by the USAAF and the RAF, reflecting the urgent reallocation of resources in early 1942.
The K-1 retained the short tail configuration and was powered by the Allison V-1710-73 engine.
P-40K-5
This block of 200 aircraft introduced a rotary valve cooling system, a notable deviation from earlier models.
The modification aimed to improve engine temperature regulation under tropical and desert conditions, though its effectiveness was mixed.
These aircraft retained the short tail and were primarily used in training and second-line roles as newer variants entered service.
P-40K-10
A total of 335 aircraft in this block were fitted with the extended tail assembly first seen on the P-40F-5.
This change significantly improved directional stability, especially during takeoff and high-speed maneuvers.
The K-10 retained the Allison V-1710-73 engine and was widely deployed in combat theaters, including North Africa and the China-Burma-India front.
P-40K-15
This final production block of 165 aircraft was equipped with winterization features, including engine and cockpit heating systems, improved insulation, and cold-weather lubricants.
These modifications made the K-15 suitable for operations in northern climates, particularly in Alaska and the Aleutian Islands.
TP-40K
A single P-40K airframe was converted into a two-seat trainer configuration, designated TP-40K.
This aircraft featured a second cockpit for instructional use and was employed in pilot transition training.
It remained a one-off modification and did not enter serial production.
XP-40K
An experimental conversion of a P-40K-10, this aircraft was fitted with the Allison V-1710-43 engine and wing root radiators for aerodynamic testing.
The XP-40K served as a testbed for cooling system innovations and radiator placement, contributing data to later P-40 developments and other Allison-powered designs.
Kittyhawk Mk.III (1st Batch)
Under the British Commonwealth naming system, 351 P-40Ks were delivered to the RAF as Kittyhawk Mk.III fighters via Lend-Lease.
These aircraft were equipped with the long tail and saw extensive service in North Africa, the Mediterranean, and Southeast Asia.
Approximately half were reallocated to other Allied air forces, including the Royal Australian Air Force (RAAF) and the Soviet Air Force.
P-40L-1
50 aircraft built.
These were essentially P-40F-5 airframes with non-essential equipment removed to reduce weight.
Intended to improve climb rate and agility, this block marked the beginning of Curtiss’s effort to lighten the Warhawk without altering its core structure.
P-40L-5
220 aircraft produced.
This variant omitted two of the six wing-mounted .50 calibre machine guns and reduced internal fuel capacity.
The changes aimed to enhance performance at medium altitudes, though they slightly compromised range and firepower.
P-40L-10
148 aircraft built.
Introduced electric aileron trim tabs for improved lateral control and revised engine control systems for smoother throttle response.
These refinements were particularly beneficial in combat manoeuvring and formation flying.
P-40L-15
112 aircraft built.
Featured improved carburettor air filters to enhance engine reliability in dusty or tropical environments.
Signal lighting was also revised to improve visibility and coordination during multi-aircraft operations.
P-40L-20
170 aircraft built.
Incorporated upgraded radio and electrical systems for better communication and reliability.
Notably, this block included provisions for an incendiary grenade release mechanism, likely intended for emergency destruction or ground attack missions.
P-40R-2
At least 53 aircraft converted.
These were P-40F or L airframes re-engined with the Allison V-1710-81 inline engine following shortages of the Packard-built Merlin V-1650.
Although performance was slightly reduced, the conversions allowed continued use of existing airframes.
Hawk 87B-3 Export variant.
100 aircraft delivered to the Royal Air Force as Kittyhawk Mk. II, and a further 160 as Kittyhawk Mk.III.
Most retained the three-gun wings of the P-40F, offering enhanced firepower.
These aircraft served primarily in North Africa and the Mediterranean, often in tactical ground support and convoy escort roles.
P-40M-1
The first 60 aircraft of the production run.
These retained the basic configuration of the late P-40K series but incorporated the new V-1710-81 engine and cooling modifications.
Most were delivered to Commonwealth forces, though some were diverted to USAAF units for training and rear-area defense.
P-40M-5
260 aircraft built.
This block introduced improved carburetor air filters to enhance engine reliability in dusty or humid environments.
Aileron control surfaces were refined to reduce stick forces and improve roll response, particularly beneficial in low-altitude combat and formation flying.
P-40M-10
280 aircraft built.
Featured changes to the fuel system, including revised plumbing and venting to reduce vapor lock and improve fuel delivery under high-G conditions.
The undercarriage warning system was updated to provide more reliable gear position alerts, addressing previous issues with false indications during landing approaches.
TP-40M
A small number of P-40Ms were converted into two-seat trainers, designated TP-40M.
These retained full flight controls in both cockpits and were used primarily for advanced fighter transition training.
Modifications included a lengthened canopy and reconfigured fuel system to accommodate the second seat.
Kittyhawk Mk.III (2nd Batch)
466 P-40M aircraft were delivered to the Royal Air Force, Royal Australian Air Force, and Royal New Zealand Air Force under the designation Kittyhawk Mk.III.
This designation was also used for P-40Ks, leading to postwar confusion in unit records and restoration efforts.
Commonwealth aircraft often featured British radios, harnesses, and tropical filters.
Many were later diverted to other Allied nations, including South Africa and the Soviet Union, where they were used in both combat and training roles.
P-40N-1
First 400 aircraft.
Featured a lighter airframe with structural simplifications, deletion of two wing-mounted machine guns (leaving four), smaller diameter undercarriage tires for weight savings, aluminium radiators and oil coolers, and head armour for pilot protection.
These changes improved climb rate and extended range, though at the cost of reduced firepower.
P-40N-5
1,100 aircraft built.
Reintroduced the full six .50 calibre wing-mounted machine guns and added wing racks for bombs or drop tanks, restoring ground attack capability.
A revised cockpit canopy with a deeper rear section improved rearward visibility, addressing a long-standing pilot complaint.
P-40N-10
100 aircraft built.
Winterized for cold-weather operations, primarily in Alaska and the Aleutians.
Modifications included engine and cockpit insulation, de-icing provisions, and retention of the four-gun wing configuration to reduce weight.
P-40N-15
377 aircraft built.
Returned to the six-gun wing layout and introduced a relocated battery for better weight distribution.
Wing fuel tanks were enlarged to increase range, making this block suitable for long-range escort and patrol missions.
P-40N-20
1,523 aircraft built.
Powered by the improved Allison V-1710-99 engine, offering better high-altitude performance and reliability.
This block became the backbone of late-war P-40 operations in the Pacific and China-Burma-India theatres.
P-40N-25
500 aircraft built.
Featured a revised instrument panel layout for improved ergonomics and visibility.
Non-metallic fuel tanks were introduced to reduce weight and simplify production, though they were more vulnerable to damage.
P-40N-26
Reconnaissance variant of the P-40N-25.
Designated RP-40N-26 in some records.
These aircraft retained the revised cockpit and fuel system but were equipped with camera gear for tactical reconnaissance.
P-40N-30
500 aircraft built.
Incorporated valve timing changes and electrical system refinements to improve engine efficiency and reduce maintenance demands.
These aircraft were often used in training and rear-area defence roles.
P-40N-35
500 aircraft built.
Introduced further system upgrades and a new radio set compatible with updated Allied communication protocols.
These aircraft were among the most reliable of the series and saw extensive use in mixed-role squadrons.
P-40N-40
220 aircraft built.
Powered by the 1,360 hp Allison V-1710-115 engine.
Featured metal-covered ailerons for improved control response, redesigned fuel tanks for better safety and capacity, a new oxygen system for high-altitude operations, and flame-dampening exhaust stacks to reduce visibility during night missions.
An additional order for 780 aircraft was placed but later cancelled due to the war’s end and the arrival of more advanced fighters.
TP-40N
Approximately 30 aircraft modified or factory-built with a second seat for training purposes.
These retained full flight controls in both cockpits and were used for advanced fighter transition and instructor familiarization.
Some were designated RP-40N-26 (TP-40N-25) and P-40N-31 (TP-40N-30), reflecting their block origins.
Hawk 87V and 87W
Export designations for P-40N aircraft delivered under Lend-Lease.
A total of 586 were built for the Royal Air Force as Kittyhawk Mk.IV.
These aircraft were also supplied to the Royal Australian Air Force, Royal New Zealand Air Force, and other Allied nations.
Commonwealth modifications included British radios, harnesses, and tropical filters.
Many were used in ground attack and convoy escort roles in Southeast Asia and the Pacific.
XP-40N
An unofficial designation applied to a single P-40N modified with a bubble canopy.
Sources differ on its origin:
one account claims it was converted from a P-40N-25 and subsequently became the third XP-40Q.
Another suggests it originated from a P-40K-1 and was later redesignated as the second XP-40Q.
However, this latter theory is considered unlikely, as photographic evidence confirms the aircraft featured the extended tail introduced with the P-40K-10 variant.
XP-40Q-1 (Model 87X)
The Curtiss XP-40Q-1 was the first of three experimental prototypes developed in 1943 as part of Curtiss’s final effort to modernize the aging P-40 Warhawk series.
Based on a modified P-40K airframe, the XP-40Q-1 featured a more powerful Allison V-1710-121 engine rated at 1,425 hp, equipped with water injection and driving a four-bladed propeller.
Its most distinctive upgrades included a streamlined nose, relocated wing-mounted cooling intakes, and a redesigned canopy with bulletproof glass.
Despite these enhancements, the aircraft retained many legacy design elements, limiting its competitiveness against newer fighters like the P-51 Mustang.
Though it achieved a top speed exceeding 420 mph, the XP-40Q-1 remained a prototype and was ultimately sidelined as the Warhawk series was phased out.
XP-40Q-2
The Curtiss XP-40Q-2, retaining serial number 42-9987, is shown following its conversion to a bubble canopy configuration.
The oil cooler and engine air intake were repositioned to a unified scoop beneath the engine, while the coolant radiators were relocated outward, beyond the main landing gear.
Although the aircraft initially retained the standard P-40 wing design, the tips were subsequently shortened by approximately one foot.
XP-40Q-2A
The XP-40Q-2A (serial 42-45722) closely resembled the earlier XP-40Q-2, distinguished primarily by its clipped wings.
Throughout its service life, the aircraft underwent minimal modifications.
XP-40Q-3
The Curtiss XP-40Q-3 was the final iteration in the XP-40Q experimental series, representing Curtiss’s last attempt to modernize the P-40 Warhawk platform.
Built from a P-40N airframe, the XP-40Q-3 incorporated all major refinements seen in earlier prototypes, including a bubble canopy, clipped wings, and a streamlined fuselage.
It was powered by the Allison V-1710-121 engine with water injection, driving a four-bladed propeller.
These upgrades enabled the aircraft to reach a top speed of approximately 422 mph, making it the fastest Warhawk ever built.
Despite its improved performance, the XP-40Q-3 was outclassed by contemporary fighters like the P-51 Mustang and P-47 Thunderbolt, and the project was ultimately discontinued without entering production.
P-40 Twin
The Twin P-40 was an experimental modification of the standard P-40 Warhawk, featuring:
One standard P-40 fuselage, retaining its original canopy and cockpit layout
Two wing-mounted engines, one in each wing, replacing the single nose-mounted Allison engine
Reinforced wing structure, likely adapted to support the added weight and thrust
Standard tail configuration, with no twin-boom or twin-fuselage elements.
The Twin P-40 was conceived during Curtiss’s final efforts to extend the Warhawk’s relevance in the face of more advanced designs like the P-51 Mustang.
While innovative, the concept never progressed beyond prototype form.
