While the P-39 had originally been introduced as an interceptor, later in its development it was decided to reduce the cost and complexity of the engine by removing the turbocharger and replacing it with a simpler mechanical supercharger. High-altitude performance suffered dramatically as a result, and Bell proposed an experimental series to test out a variety of solutions. The resulting XP-39E featured two primary changes from the earlier P-39D from which it was developed. One change was the addition of a new laminar flow wing section, which had recently been revealed to the industry through a National Advisory Committee for Aeronautics (NACA) research project. The other was a switch to the Continental I-1430 engine, which featured an improved overall design developed from the hyper engine efforts, as well as an improved supercharger. Three prototypes were ordered in April 1941 with serials 41-19501, 41-19502 and 42-7164. The V-1430 was having continued development problems and could not be delivered in time, so it was replaced by the newer -47 version of the Allison V-1710 that powered the basic P-39. Each of the prototypes tested different wing and tail configurations: 41-19501 had a rounded vertical tail, but the tailplane had squared-off tips, 41-19502 had a squared-off fin and rudder and large wing fillets while 42-7164 had all its flight surfaces squared off. The XP-39E proved to be faster than the standard Airacobra; a maximum speed of 386 mph (621 km/h) being attained at 21,680 ft (6,610 m) during tests. However, the XP-39E was considered to be inferior to the stock P-39 Airacobra in all other respects, so it was not ordered into production.
XP-63
Bell plant assembly line near Niagara Falls, New York
Although the XP-39E proved to be disappointing, the USAAF was nevertheless interested in an even larger aircraft based on the same basic layout. Even before its first flight, the USAAF placed an order on 27 June 1941 for two prototypes of an enlarged version powered by the same V-1710-47 engine. The new design was given the designation XP-63 and serials were 41-19511 and 41-19512. A third prototype was also ordered, 42-78015, this one featuring the Packard V-1650, the U.S.-built version of the Rolls-Royce Merlin engine. The XP-87897 was larger in all dimensions than the Airacobra. The laminar flow wings increased the overall span by 4.33 ft (1.32 m) to 38.33 ft (11.68 m). The engine was fitted with a second supercharger supplementing the normal single-stage supercharger. At higher altitudes when additional boost was required, a hydraulic clutch would engage the second supercharger, adding 10,000 ft (3,000 m) to the service ceiling. A larger four-bladed propeller was also standardized. A persistent complaint against the Airacobra was that its nose armament was not easily accessible for ground maintenance, and in order to cure this problem, the XP-63 airframe was fitted with larger cowling panels. In September 1942, even before the prototype flew, the USAAF ordered it into production as the P-63A (Model 33). The P-63A's armament was to be the same as that of the then-current P-39Q, a single 37 mm (1.46 in) M4 cannon firing through the propeller hub, two .50 in (12.7 mm) machine guns in the upper nose firing through the prop, and two .50 in (12.7 mm) machine guns in underwing gondolas. The trajectory of the .50 in guns was far flatter than that of the cannon. The first prototype, 41-19511, flew for the first time on 7 December 1942. It was destroyed on 28 January 1943 when its landing gear failed to extend. The second prototype, 41-19512, followed on 5 February 1943. It too was destroyed, this time due to an engine failure. The Merlin-engined 42-78015 was later delivered with another Allison instead, as the Merlins were primarily needed for the P-51 Mustang. Nevertheless the new -93 version of the Allison had a war emergency rating of 1,500 hp (1,100 kW) at sea level, making this prototype one of the fastest Kingcobras built, attaining 421 mph (678 km/h) at 24,100 ft (7,300 m). Deliveries of production P-63As began in October 1943. The USAAF concluded the Kingcobra was inferior to the Mustang, and declined to order larger quantities. American allies, particularly the Soviet Union, had a great need for fighter aircraft, however, and the Soviets were already the largest users of the Airacobra. Therefore, the Kingcobra was ordered into production to be delivered under Lend-Lease. In February 1944, the Soviet government sent a highly experienced test pilot, Andrey G. Kochetkov, and an aviation engineer, Fyodor P. Suprun, to the Bell factories to participate in the development of the first production variant, the P-63A. Initially ignored by Bell engineers, Kochetkov's expert testing of the machine's spin characteristics (which led to airframe buckling) eventually led to a significant Soviet role in the development. After flat spin recovery proved impossible, and upon Kochetkov's making a final recommendation that pilots should bail out upon entering such a spin, he received a commendation from the Irving Parachute Company. The Kingcobra’s maximum aft CG was moved forward to facilitate recovery from spins.[3] P-63A-8, SN 269261, was extensively tested at TsAGI in what was then the world's largest wind tunnel. Soviet input was significant. With the Soviet Union being the largest buyer of the aircraft, Bell was quick to implement their suggestions. The vast majority of the changes in the A sub-variants were a direct result of Soviet input, e.g. increased pilot armor and fuselage hardpoint on the A-5, underwing hardpoints and extra fuel tanks on the A-6, etc. The Soviet Union even experimented with ski landing gear for the P-63A-6, but this never reached production. Most significantly, Soviet input resulted in moving the main cannon forward, favorably changing the center of gravity, and increasing its ammo load from 30 to 58 rounds for the A-9 variant. The P-63 had an impressive roll rate, besting the P-47, P-40, N1K2 and P-51 with a rate of 110° per second at 275 mph (443 km/h).[4]
Swept-wing L-39
L-39 with swept wings, extended rear fuselage, ventral tail fin and P-39 prop
Two war surplus P-63Cs were modified by Bell under Navy contract for flight testing of low-speed and stall characteristics of high-speed wing designs. The aircraft received new wings with adjustable leading edge slats, trailing edge flaps and a pronounced sweep of 35 degrees. The wings had no wheel wells; only the nose gear was retractable.[5] L-39-1 first flew 23 April 1946, demonstrating a need for extra tail surface and rear fuselage length to balance the aircraft in flight - the wing repositioning reduced empennage effectiveness and moved the center of lift aft. A lighter three-bladed propeller from a P-39Q-10 was mounted and the necessary changes to the empennage were made. L-39-2 incorporated these adjustments from the start. L-39-1 later went to NACA at Langley for wind tunnel testing, where much valuable data were gathered.[6] L-39-2 also served as a testbed for the Bell X-2 40-degree wing design.[unreliable source?][7]
Operational service
USAAF P-63A USAF photo
The first version to be supplied in quantity to the USSR was the P-63A-7 with a higher horizontal tail, and reinforced wings and fuselage. The fuselage proved to require strengthening, consequently in October 1944, a reinforcement kit for operational P-63s was developed.[8]) Air Transport Command ferry pilots, including U.S. women pilots of the WASP program, picked up the planes at the Bell factory at Niagara Falls, New York, and flew them to Great Falls, Montana and then onward via the Alaska-Siberia Route (ALSIB), through Canada, over Alaska where Russian ferry pilots, many of them women, would take delivery of the aircraft at Nome[9] and fly them to the Soviet Union over the Bering Strait. A total of 2,397 (2,672, according to other sources [10]) such aircraft were delivered to USSR, out of the overall 3,303 production aircraft (72.6%).[11] By a 1943 agreement, P-63s were disallowed for Soviet use against Germany and were supposed to be concentrated in the Soviet Far East for an eventual attack on Japan.[citation needed] However, there are many unconfirmed reports from both the Soviet and German side that P-63s did indeed see service against the Luftwaffe. Most notably, one of Pokryshkin's pilots reports in his memoirs published in the 1990s that the entire 4th GvIAP was secretly converted to P-63s in 1944, while officially still flying P-39s. One account states they were in action at Königsberg, in Poland and in the final assault on Berlin. There are German reports of P-63s shot down by both fighters and flak. Nevertheless, all Soviet records show nothing but P-39s used against Germany. In general, official Soviet histories played down the role of Lend-Lease supplied aircraft in favor of local designs, but it is known that the P-63 was a successful ground attack aircraft in Soviet service. The Soviets developed successful group aerial fighting tactics for the Bell fighters and P-39s scored a surprising number of aerial victories over German aircraft, mostly Junkers Ju-87Stukas and bombers but including many advanced fighters as well. Low ceilings, short missions, good radios, a sealed and warm cockpit and ruggedness contributed to their effectiveness. To pilots who had once flown the tricky Polikarpov I-16, the aerodynamic quirks of the mid-engined aircraft were unimportant. In the Far East, P-63 and P-39 aircraft were used in the Soviet invasion of Manchukoku and northern Korea. In the Pacific theatre, the Kingcobras flew escort, close air support and ground attack missions. The Soviet P-63s achieved their first air victory on 15 August 1945, when Lejtenant I. F. Miroshnichenko from 17th IAP/190 IAD, shot down a Nakajima Ki-43 Hayabusa Army fighter, off the coast of North Korea.[10] Sufficient aircraft continued in use after the war for them to be given the NATO reporting name of Fred. By 9 May 1945, operational units had still 1,148 Kingcobras on strength.[10] On 8 October 1950, two USAF F-80Cs from 49 FG breached the USSR's border and attacked Sukhaya Rechka airfield, making two strafing runs before returning to their home base. Although Soviet sources claim the attack was intentional, the pilots claimed it was a result of a navigational error.[12] The airfield belonged to the VVS TOF, but it was occupied by the 821 IAP / 190 IAD. Mostly aircraft of the 1st Squadron of 821 IAP were hit with 12 P-63s damaged, one P-63 burned to the ground while the other damaged aircraft were able to be repaired. No human losses were suffered.[13] In 1945, 114 later models were delivered to the French Armée de l'Air, but they arrived too late to see service in World War II. They however saw service during the First Indochina War before being replaced in 1951.
"Pinball" operations
Its main use in American service was the unusual one of a manned flying target for gunnery practice.[citation needed] The aircraft was generally painted bright orange to increase its visibility. All armament and the regular armor was removed from these RP-63 aircraft, and over a ton of armored sheet metal was applied to the aircraft. This was fitted with sensors that would detect hits, and these hits were signaled by illuminating a light in the propeller hub where the cannon would have been. This earned the aircraft the unofficial nickname of Pinball. Special frangible rounds made of a lead/bakelite combination were developed that would disintegrate upon impact. These were known as the "Cartridge, Caliber .30, Frangible, Ball, M22." Ivan L. Hickman, a veteran Pinball pilot, eventually authored Operation Pinball, the most authoritative[citation needed] book on the series, published in 1990 by Motorbooks.
Postwar air racers
Numerous surplus P-63s ended up on the air racing circuit in the immediate postwar era. Charles Tucker purchased two P-63s from the disposal facility at Kingman, Arizona just after the war. He entered one of them, the Tucker Special as Race 28 with the name Flying Red Horse emblazoned on the nose (civilian register N62995) in the 1946 Thompson Trophy race. He had clipped the wing 12 ft, 9 inches in an attempt to improve its speed, reducing the span to 25 ft, 9 inches. The second one (44-4126 (XN63231 Race 30) was intended for the 1946 Bendix cross country race. It was initially fitted with two wingtip drop tanks. In 1947, the drop tanks were removed and the wings were clipped to 28 ft 6 in (8.69 m) Two other significant racers were flown later. Tipsy Miss, John Sandberg's clipped-wingtip P-63 unlimited racer, was identified as "Race 28," and painted in bright orange, white and black race numbers with a chrome spinner. Later sold to a European pilot, this P-63 was destroyed in an accident in 1990[14]Crazy Horse Campgrounds was the most radically modified P-63 Kingcobra ever. Larry Haven's "Race 90" clipped-wing unlimited racer had a tiny bubble canopy installed; it appeared in all silver (unpolished aluminum) finish with a white rudder and black trim. The aircraft later crashed into the ocean on a test flight in 1972.[15]
Variants
P-63 with underwing gun pods
XP-63 Prototypes (two) (company designation was Model 24); USAAF serials (41-19511 and 41-19512).
XP-63A Following the loss of the first two prototypes, an additional test aircraft was procured, USAAF serial 42-78015, originally ordered as a testbed for the proposed Rolls-Royce Merlin-poweredP-63B.
P-63A The production model Bell Model 33; 1725 P-63As produced in various sub-marks.
P-63B Proposed Rolls-Royce Merlin-poweredP-63B series was cancelled due to lack of availability of Merlin engines.
P-63C Second production series differed from the P-63A by being powered by the uprated Allison V-1710-117 engine with a war emergency rating of 1,500 hp (1,100 kW) at sea level and 1,800 hp (1,300 kW) with water injection. The wingspan was reduced by 10 inches. A total production run of 1,777 was completed.[unreliable source?][16]
P-63D One aircraft (43-11718) powered by an Allison V-1710-109 (E22) 1,425 hp featured 0.83 ft (0.25 m) wingspan increase (to 39.17 ft/ m), gross area being increased to 255 sq ft (23.7 m2) and, most noticeably, a rearward-sliding bubble canopy. The series was cancelled in 1945.[unreliable source?][16]
P-63E Essentially similar to the P-63D with the exception of a ventral fin extension and the use of a standard "cab"-style cockpit; only 13 built.
P-63F Bell Model 43 variant featured an enlarged vertical tail and Allison V-1710-135; only two (43-11719 and 43-11722) built.
RP-63A/C "Pinball" Target aircraft with five modified from P-63As and 95 modified on production lines; in 1948, surviving RP-63A aircraft were redesignated QF-63A. A further 200 production RP-63C aircraft were modified on the production line. Similarly, the surviving RP-63Cs were redesignated RP-63Cs. Many of the "target" aircraft were actually used as target tugs.
L-39-2 with swept wings and four-bladed prop.
RP-63G "Pinball" "Dedicated" flying targets which included two prototypes (43-11723 and 11724) and 30 production aircraft that incorporated a flush dorsal inlet but, more significantly, lights that would come on when the target was struck with frangible munitions. In 1948, the remaining RP-63Gs were redesignated QF-63Gs.[unreliable source?][16]
L-39 Two war surplus P-63Cs modified by Bell under Navy contract for flight testing of low-speed and stall characteristics of high-speed wing designs.
The Bell P-59 Airacomet was the first American jetfighter aircraft, designed and built during World War II. The United States Army Air Forces was not impressed by its performance and cancelled the contract when fewer than half of the aircraft ordered had been produced. Although no P-59s went into combat, it paved the way for another design generation of U.S. turbojet-powered aircraft and was the first turbojet fighter to have its turbojet engine and inlet nacelles integrated within the main fuselage.
Contents
1Design and development
2Operational service
3Variants
4Operators
5Survivors
6Specifications (P-59B)
Design and development
Major General Henry H. Arnold became aware of the United Kingdom's jet program when he attended a demonstration of the Gloster E.28/39 in April 1941. The subject had been mentioned, but not in depth, as part of the Tizard Mission the previous year. He requested, and was given, the plans for the aircraft's powerplant, the Power Jets W.1, which he took back to the U.S. On 4 September, he offered the U.S. company General Electric a contract to produce an American version of the engine. On the following day, he approached Lawrence Dale Bell, head of Bell Aircraft Corporation, to build a fighter to utilize it. Bell agreed and set to work on producing three prototypes. As a disinformation tactic, the USAAF gave the project the designation P-59A, to suggest it was a development of a completely unrelated Bell XP-59 fighter project that had been canceled. The design was finalized on 9 January 1942, and construction began. In March, long before the prototypes were completed, an order for 13 YP-59A pre-production machines was added to the contract.
Bell XP-59 wind tunnel model. Original pusher-propeller design.
On 12 September 1942, the first XP-59A was sent to Muroc Army Air Field (today, Edwards Air Force Base) in California by train for testing, taking seven days to reach Muroc.[1] While being handled on the ground, the aircraft was fitted with a dummy propeller to disguise its true nature.[2] The aircraft first became airborne during high-speed taxiing tests on 1 October with Bell test pilot Robert Stanley at the controls, although the first official flight was made by Col Laurence Craigie the next day.[1] Over the following months, tests on the three XP-59As revealed a multitude of problems including poor engine response and reliability (common shortcomings of all early turbojets), insufficient lateral stability, i.e., in the roll axis,[3] and performance that was far below expectations. Chuck Yeager flew the aircraft and was dissatisfied with the speed, but was amazed at the smooth flying. Nevertheless, even before delivery of the YP-59As in June 1943, the USAAF ordered 80 production machines, designated P-59A Airacomet.
Operational service
P-59A (S/N 44-22609, first production -A model) and P-63 (S/N 42-69417) in flight.
The 13 service test YP-59As had a more powerful engine than its predecessor, but the improvement in performance was negligible with only a five mph increase in top speed. One of these aircraft, the third YP-59A (S/n: 42-22611) was supplied to the RAF, becoming RG362/G, in exchange for the first production Gloster Meteor I, EE210/G.[4] British pilots found that the aircraft compared very unfavorably with the jets that they were already flying. (The YP-59A also compared unfavorably to the propeller-driven P-51 Mustang.) Two YP-59A Airacomets (42-108778 and 42-100779) were also delivered to the U.S. Navy where they were evaluated as the YF2L-1 but quickly found completely unsuitable for carrier operations. Faced with their own ongoing difficulties, eventually, Bell completed 50 production Airacomets, 20 P-59As and 30 P-59Bs. Each was armed with one 37 mm M4 cannon and 44 rounds of ammunition and three .50 cal. machine guns with 200 rounds per gun. The P-59Bs were assigned to the 412th Fighter Group to familiarize AAF pilots with the handling and performance characteristics of jet aircraft.[5] While the P-59 was not a great success, the type did give the USAAF experience with the operation of jet aircraft in preparation for the more advanced types that would shortly become available.[6]
Variants
P-59A Airacomet with the short-lived red outlined National markings (June 1943 to September 1943).
XP-59
Unrelated piston engine powered pusher propeller design developed from the Bell XP-52. Not built.
XP-59A
Prototype of the jet engine powered version, 3 built, serial numbers 42-108784/108786.
YP-59A
Series of test aircraft, 13 built, serial numbers 42-108771/108783.
YF2L-1
Two YP-59A (42-108778/108779) delivered to the US Navy for carrier evaluation as Bu63960/63961.
P-59A
First production version, 20 built, serial numbers 44-22609/22628.
P-59B
Improved P-59A. 80 aircraft ordered but only 30 built, serial numbers 44-22629/22658, further 50 (44-2659/22708) canceled.
Operators
Bell P-59B Airacomet 3/4 front view of Reluctant Robot.
Bell YP-59A in flight. X and Y aircraft had rounded vertical stabilizers and wingtips while the production A and B models had squared surfaces. The YP-59A can be distinguished from the XP-59A because Ys had nose armament.
The Bell P-39 Airacobra was one of the principal American fighter aircraft in service at the start of World War II. It was the first fighter in history with a tricycle undercarriage and the first to have the engine installed in the center fuselage, behind the pilot.[2] Although its mid-engine placement was innovative, the P-39 design was handicapped by the lack of an efficient turbo-supercharger, limiting it to low-altitude work. The P-39 was used with great success by the Soviet Air Force, who scored the highest number of individual kills attributed to any U.S. fighter type.[N 1] Other important users were the Free French and co-belligerent Italian air forces.[3] Together with the derivative P-63 Kingcobra, these aircraft became the most successful mass-produced fixed-wing aircraft manufactured by Bell.[4]
Contents
1Design and development
1.1Technical details
2Operational history
2.1United Kingdom
2.2U.S.
2.3USSR
2.4Australia
2.5France
2.6Italy
2.7Portugal
3Postwar
4Racing Airacobras
5Variants
5.1XP-39
5.2YP-39
5.3XP-39B
5.4P-39C
5.5Airacobra I
5.6P-39D
5.7XP-39E
5.8P-39F
5.9P-39G
5.10P-39H
5.11P-39J
5.12P-39K
5.13P-39L
5.14P-39M
5.15P-39N
5.16P-39P
5.17P-39Q
5.18Other
6Operators
7Survivors
8Specifications (P-39Q)
9Notable appearances in media
Design and development
In February 1937, Lieutenant Benjamin S. Kelsey, Project Officer for Fighters at the United States Army Air Corps (USAAC), issued a specification for a new fighter via Circular Proposal X-609.[5] It was a request for a single-engine high-altitude "interceptor" having "the tactical mission of interception and attack of hostile aircraft at high altitude".[6] Despite being called an interceptor, the proposed aircraft's role was simply an extension of the traditional pursuit (fighter) role, using a heavier and more powerful aircraft at higher altitude. Specifications called for at least 1,000 lb of heavy armament including a cannon, a liquid-cooled Allison engine with a General Electricturbo-supercharger, tricycle landing gear, a level airspeed of at least 360 mph (580 km/h) at altitude, and a climb to 20,000 ft (6,100 m) within 6 minutes;[7] the toughest set of specifications USAAC had presented to that date.[N 2] Although Bell's limited fighter design work had previously resulted in the unusual Bell YFM-1 Airacuda, the Model 12[9] proposal adopted an equally original configuration with an Allison V-12 engine mounted in the middle of the fuselage, just behind the cockpit, and a propeller driven by a shaft passing beneath the pilot's feet under the cockpit floor.[9] The main purpose of this configuration was to free up space for the heavy main armament, a 37 mm (1.46 in) OldsmobileT9cannon firing through the center of the propeller hub for optimum accuracy and stability when firing.[N 3] This happened because H.M. Poyer, designer for project leader Robert Woods, was impressed by the power of this weapon and he pressed for its incorporation though the original concept had been a 20–25 mm (.79–98 in) cannon mounted conventionally in the nose. This was unusual, because fighters had previously been designed around an engine, not a weapon system. Although devastating when it worked, the T9 had very limited ammunition, a low rate of fire, and was prone to jamming.[10] A secondary benefit of the mid-engine arrangement was to create a smooth and streamlined nose profile. Entry to the cockpit was through side doors (mounted on both sides of the cockpit) rather than a sliding canopy. Its unusual engine location and the long driveshaft caused some concern to pilots at first, but experience showed this was no more of a hazard in a crash landing than with an engine located forward of the cockpit. There were no problems with propshaft failure. As originally designed, the XP-39 had a turbocharger with a scoop on the left side of the fuselage;[11] both were deleted for production.[12] The production P-39 retained a single-stage, single-speed supercharger with a critical altitude (above which performance declined) of about 12,000 feet (3,660 m) (3,658 m).[13]
Bell P-39 Airacobra center fuselage detail with maintenance panels open.
The XP-39 made its maiden flight on 6 April 1938[14] at Wright Field, Ohio, achieving 390 mph (630 km/h) at 20,000 ft (6,100 m), reaching this altitude in only five minutes.[15] The Army ordered twelve YP-39s (with only a single-stage, single-speed supercharger) for service evaluation[14] and one YP-39A. After these trials were complete, which resulted in detail changes including deletion of the external radiator,[14][16] and on advice from NACA,[14] the prototype was modified as the XP-39B; after demonstrating a performance improvement,[14] the 13 YP-39s were completed to this standard, adding two .30 in (7.62 mm) machine guns to the two existing .50 in (12.7 mm) guns.[14] Lacking armor or self-sealing fuel tanks, the prototype was one ton (900 kg) lighter than the production fighters.[17] After completing service trials, and originally designated P-45, a first order for 80 aircraft was placed 10 August 1939; the designation reverted before deliveries began.[14]
Technical details
The P-39 was an all-metal, low-wing, single-engine fighter, with a tricycle undercarriage and an Allison V-1710 liquid-cooled V-12 engine mounted in the central fuselage, directly behind the cockpit. The Airacobra was one of the first production fighters to be conceived as a "weapons system"; in this case the aircraft (known originally as the Bell Model 4) was designed around the 37mm T9 cannon.[18] This weapon, which was designed in 1934 by the American Armament Corporation, a division of Oldsmobile, fired a 1.3 lb (610 g) projectile capable of piercing .8 in (2 cm) of armor at 500 yd (450 m) with armor piercing rounds. The 200 lb, 90 inch long weapon had to be rigidly mounted and fire parallel to and close to the centerline of the new fighter. It would be impossible to mount the weapon in the fuselage, firing through the propeller shaft as could be done with smaller 20mm cannon. Weight, balance and visibility problems meant that the cockpit could not be placed farther back in the fuselage, behind the engine and cannon.[18] The solution adopted was to mount the cannon in the forward fuselage and the engine in the center fuselage, directly behind the pilot's seat. The tractor propeller was driven via a 10-foot-long (3.0 m) drive shaft which was made in two sections, incorporating a self-aligning bearing to accommodate fuselage deflection during violent maneuvers. This shaft ran through a tunnel in the cockpit floor and was connected to a gearbox in the nose of the fuselage which, in turn, drove the three or (later) four bladed propeller via a short central shaft. The gearbox was provided with its own lubrication system, separate from the engine; in later versions of the Airacobra the gearbox was provided with some armor protection.[18] The glycol-cooled radiator was fitted in the wing center section, immediately beneath the engine; this was flanked on either side by a single drum shaped oil cooler. Air for the radiator and oil coolers was drawn in through intakes in both wing-root leading edges and was directed via four ducts to the radiator faces. The air was then exhausted through three controllable hinged flaps near the trailing edge of the center section. Air for the carburetor was drawn in via a raised oval intake immediately aft of the rear canopy.[19][20] The fuselage structure was unusual and innovative, being based on a strong central keel which incorporated the armament, cockpit and engine. Two strong fuselage beams to port and starboard formed the basis of the structure. These angled upwards fore and aft to create mounting points for the T9 cannon and propeller reduction gearbox and for the engine and accessories respectively. A strong arched bulkhead provided the main structural point to which the main spar of the wing was attached. This arch incorporated a fireproof panel and an armor plate separating the engine from the cockpit. It also incorporated a turnover pylon and a pane of bullet-resistant glass behind the pilot's head. The arch also formed the basis of the cockpit housing; the pilot's seat was attached to the forward face as was the cockpit floor. Forward of the cockpit the fuselage nose was formed from large removable covers. A long nose wheel well was incorporated in the lower nose section. The engine and accessories were attached to the rear of the arch and the main structural beams; these too were covered using large removable panels. A conventional semi-monocoque rear fuselage was attached aft of the main structure.[19][21][22][N 4][23] Because the pilot was above the extension shaft, he was placed higher in the fuselage than in most contemporary fighters, which, in turn gave the pilot a good field of view.[18] Access to the cockpit was via sideways opening "car doors", one on either side. Both had wind-down windows; because only the right hand door had a handle both inside and outside this was used as the normal means of access. The left hand door could only be opened from the outside and was for emergency use, although both doors could be jettisoned. In service the cockpit was difficult to escape from in an emergency because the roof was fixed.[24] The complete armament fit consisted of the T9 with a pair of Browning M2 .50 caliber (12.7 mm) machine guns mounted in the nose. This would change to two .50 in (12.7 mm) and two .30 in (7.62 mm) guns in the XP-39B (P-39C, Model 13, the first 20 delivered) and two 0.50 in/12.7 mm and four 0.30 in/7.62 mm (all four in the wings) in the P-39D (Model 15), which also introduced self-sealing tanks and shackles (and piping) for a 500 lb (227 kg) bomb or drop tank.[14] Because of the unconventional layout, there was no space in the fuselage to place a fuel tank. Although drop tanks were implemented to extend its range, the standard fuel load was carried in the wings, with the result that the P-39 was limited to short range tactical strikes.[25] In September 1940, Britain ordered 386 P-39Ds (Model 14), with a 20 mm (.79 in) Hispano-Suiza HS.404 and six .303 in (7.7 mm), instead of a 37 mm (1.46 in) cannon and six 0.30 in (7.62 in) guns. The RAF eventually ordered a total of 675 P-39s. However, after the first Airacobras arrived at 601 SquadronRAF in September 1941, they were promptly recognized as having an inadequate rate of climb and performance at altitude for Western European conditions. Only 80 were adopted, all of them with 601 Squadron. Britain transferred about 200 P-39s to the Soviet Union. Another 200 examples intended for the RAF were taken up by the USAAF after the attack on Pearl Harbor as the P-400, and were sent to the Fifth Air Force in Australia, for service in the South West Pacific Theatre.[26] A heavy structure, and around 265 lb (120 kg) of armor were characteristic of this aircraft as well. The production P-39's heavier weight combined with the Allison engine having only a single-stage, single-speed supercharger, limited the high-altitude capabilities of the fighter. The P-39's altitude performance was markedly inferior to the contemporary European fighters and, as a result, the first USAAF fighter units in the European Theater were equipped with the Spitfire V. However, the P-39D's roll rate was 75°/s at 235 mph (378 km/h)– better than the A6M2, F4F, F6F, or P-38 up to 265 mph (426 km/h). (see NACA chart).[27] Above the supercharger's critical altitude of about 12,000 ft (3,658 m), an early P-39's performance dropped off rapidly. This limited its usefulness in traditional fighter missions in Europe as well as in the Pacific, where it was not uncommon for Japanese bombers to attack at altitudes above the P-39's operational ceiling (which in the tropical hot air was lower than in moderate climates). The late production N and Q models, making up 75% of all Airacobras, could maintain a top speed of approximately 375 mph (604 km/h) up to 20,000 ft (6,100 m). The weight distribution of the P-39 was supposedly the reason for its tendency to enter a dangerous flat spin, a characteristic Soviet test pilots were able to demonstrate to the skeptical manufacturer who had been unable to reproduce the effect. After extensive tests, it was determined the spin could only be induced if the aircraft was improperly loaded, with no ammunition in the front compartment. The flight manual noted a need to ballast the front ammunition compartment with the appropriate weight of shell casings to achieve a reasonable center of gravity. High speed controls were light, consequently, high speed turns and pull-outs were possible. The P-39 had to be held in a dive since it tended to level out, reminiscent of the Spitfire. Recommended dive speed limit (Vne) was 475 mph (764 km/h) for the P-39.[28] The rear-mounted engine made the aircraft ideal for ground attack since fire would be coming from the front-bottom quarter and was less likely to hit the engine and its cooling systems. The arrangement proved to be very vulnerable to attacks from above and behind and nearly any hit on the fuselage from an attacking enemy fighter was virtually guaranteed to disable the cooling system and lead to the prompt demise of the engine and thus the airplane. With its lack of high-altitude performance, the Airacobra was extremely vulnerable to any enemy fighter with decent high altitude performance.[29] By the time of the Pearl Harbor attack, nearly 600 had been built. When P-39 production ended in August 1944, Bell had built 9,558[14][16] Airacobras, of which 4,773 (mostly -39N and -39Q[14]) were sent to the Soviet Union through the Lend-Lease program. There were numerous minor variations in engine, propeller, and armament, but no major structural changes in production types, excepting a few two-seat TP-39F and RP-39Q trainers.[30][N 5] In addition, seven went to the U.S. Navy as radio-controlled drones. Trials of a laminar flow wing (in the XP-39E) and Continental IV-1430 engine (the P-76) were unsuccessful.[14] The mid-engine, gun-through-hub concept was developed further in the Bell P-63 Kingcobra. A naval version with tail-dragger landing gear, the XFL-1 Airabonita, was ordered as a competitor to the F4U Corsair and XF5F Skyrocket. It first flew 13 May 1940,[14] but after a troublesome and protracted development and testing period, it was rejected.
Operational history
The Airacobra saw combat throughout the world, particularly in the Southwest Pacific, Mediterranean and Russian theaters. Because its engine was only equipped with a single-stage, single-speed supercharger, the P-39 performed best below 17,000 feet (5,200 m) altitude. In both western Europe and the Pacific, the Airacobra found itself outclassed as an interceptor, its earliest proposed role, and the type was gradually relegated to other duties.[2] It often was used at lower altitudes for such missions as ground strafing.
United Kingdom
Airacobra I AH589L of 601 Squadron. The long-barrelled 20mm Hispano is clearly shown, as are the .303 wing guns.
In 1940, the British Direct Purchase Commission in the US was looking for combat aircraft; they ordered 675 of the export version Bell Model 14 as the "Caribou" on the strength of the company's representations on 13 April 1940. The performance of the Bell P-39 prototype and 13 test aircraft which were able to achieve a speed of 390 mph (630 km/h) at altitude was due to the installation of turbo-supercharging. The British armament was two nose mounted 0.50 in (12.7 mm) machine guns, and four 0.303 in (7.7 mm) Browning machine guns in the wings; the 37 mm gun was replaced by a 20 mm (.79 in) Hispano-Suiza. The British export models were renamed "Airacobra" in 1941. A further 150 were specified for delivery under Lend-lease in 1941 but these were not supplied. The Royal Air Force (RAF) took delivery in mid 1941 and found that performance of the non-turbo-supercharged production aircraft differed markedly from what they were expecting.[31] In some areas, the Airacobra was inferior to existing aircraft such as the Hawker Hurricane and Supermarine Spitfire and its performance at altitude suffered drastically. Tests by the R.A.E at Boscombe Down showed the Airacobra reached 355 mph (571 km/h) at 13,000 ft (3,962 m).[32] The cockpit layout was criticized, and it was noted that the pilot would have difficulty in baling out in an emergency because the cockpit roof could not be jettisoned. The lack of a clear vision panel on the windscreen assembly meant that in the event of heavy rain the pilot's forward view would be completely obliterated; the pilot's notes advised that in this case the door windows would have to be lowered and the speed reduced to 150 mph (241 km/h) [33] On the other hand it was considered effective for low level fighter and ground attack work. Problems with gun and exhaust flash suppression and the compass could be fixed. No. 601 Squadron RAF was the only British unit to use the Airacobra operationally, receiving their first two examples on 6 August 1941. On 9 October, four Airacobras attacked enemy barges near Dunkirk, in the type's only operational action with the RAF. The squadron continued to train with the Airacobra during the winter, but a combination of poor serviceability and deep distrust of this unfamiliar fighter resulted in the RAF rejecting the type after one combat mission.[3] In March 1942, the unit re-equipped with Spitfires. The Airacobras already in the UK, along with the remainder of the first batch being built in the US, were sent to the Soviet Air force, the sole exception being AH574, which was passed to the Royal Navy and used for experimental work, including the first carrier landing by a tricycle undercarriage aircraft on 4 April 1945 on HMS Pretoria Castle,[34] until it was scrapped on the recommendation of a visiting Bell test pilot in March 1946.[35]
U.S.
Bell P-39 Airacobra firing all weapons at night.
The United States requisitioned 200 of the next part of the order as the P-400. The P-400 designation came from advertised top speed of 400 mph (644 km/h). After Pearl Harbor, the P-400 was deployed to training units, but some saw combat in the Southwest Pacific including with the Cactus Air Force in the Battle of Guadalcanal.[36] Though outclassed by Japanese fighter planes, it performed well in strafing and bombing runs, often proving deadly in ground attacks on Japanese forces trying to retake Henderson Field. Guns salvaged from P-39s were sometimes fitted to Navy PT boats to increase firepower.[N 6] From September to November 1942 pilots of the 57th Fighter Squadron flew P-39s and P-38s from an airfield built on land bulldozed into Kuluk Bay on the barren island of Adak in Alaska's Aleutian Islands. They attacked the Japanese forces which had invaded Attu and Kiska islands in the Aleutians in June 1942. The factor that claimed the most lives was not the Japanese but the weather. The low clouds, heavy mist and fog, driving rain, snow and high winds made flying dangerous and lives miserable. The 57th remained in Alaska until November 1942 and then returned to the United States. In North Africa, the Tuskegee Airmen were assigned P-39s in February 1944. They successfully transitioned and carried out their duties including supporting Operation Shingle over Anzio as well as missions over the Gulf of Naples in the Airacobra but achieved few aerial victories.[37] By June they had transitioned to P-47 Thunderbolts and then P-51 Mustangs in July 1944. While only one U.S. pilot, Lt. Bill Fiedler, became an ace in a P-39, many U.S. aces scored one or two of their victories in the aircraft.[38]
USSR
P-39Q-15BE 44-2664 Aviation Museum of Central Finland
The most successful use of the P-39 was in the hands of the Soviet Air Force (VVS). They received the considerably improved N and Q versions of the Airacobra. The tactical environment of the Eastern Front did not demand the extreme high-altitude operations that the RAF and United States Army Air Forces (USAAF) employed with their big bombers. The low-speed, low-altitude turning nature of most air combat on the Russian Front suited the P-39's strengths: sturdy construction, reliable radio gear, and adequate firepower. Russian pilots appreciated the cannon-armed P-39 primarily for its air-to-air attack capability. The usual nickname for the well-loved Airacobra in the VVS was Kobrushka, "little cobra", or Kobrastochka, a portmanteau of Kobra and Lastochka (swallow), "dear little cobra".[39][40] Soviet pilot Nikolai G. Golodnikov, in an interview with Andrei Sukhrukov, recalled:
"I liked the Cobra, especially the Q-5 version. It was the lightest version of all Cobras and was the best fighter I ever flew. The cockpit was very comfortable, and visibility was outstanding. The instrument panel was very ergonomic, with the entire complement of instruments right up to an artificial horizon and radio compass. It even had a relief tube in the shape of a funnel. The armored glass was very strong, extremely thick. The armor on the back was also thick. The oxygen equipment was reliable, although the mask was quite small, only covering the nose and mouth. We wore that mask only at high altitude. The HF radio set was powerful, reliable and clear." [41]
The first Soviet Cobras had a 20 mm Hispano-Suiza cannon and two heavy Browning machine guns, synchronized and mounted in the nose. Later, Cobras arrived with the M-4 37 mm cannon and four machine guns, two synchronized and two wing-mounted. "We immediately removed the wing machine guns, leaving one cannon and two machine guns," Golodnikov recalled later.[41] That modification improved roll rate by reducing rotational inertia. Soviet airmen appreciated the M-4 cannon with its powerful rounds and the reliable action but complained about the low rate of fire (three rounds per second) and inadequate ammunition storage (only 30 rounds).[41] The Soviets used the Airacobra primarily for air-to-air combat[42] against a variety of German aircraft, including Messerschmitt Bf 109s, Focke-Wulf Fw 190s, Junkers Ju 87s, and Ju 88s. During the battle of Kuban River, the Soviet air force relied on P-39s much more than Spitfires and P-40s. Aleksandr Pokryshkin, from 16.Gv.IAP, claimed 20 air victories in that campaign.[43] Pokryshkin, the third-highest scoring Allied ace (with a score of 53 air victories plus six shared)[44] flew the P-39 from late 1942 until the end of the war (though rumors exist that he changed in late 1944 to a P-63 Kingcobra). Grigoriy Rechkalov, second Soviet top-scoring ace (56 individual air victories plus 5 shared), occasionally his wingman while both in 16.Gv.IAP,[45] scored 44 victories flying Airacobras. The majority of his kills were achieved on P-39N-0 number 42-8747 and P-39Q-15 number 44-2547. During the Great Patriotic War, he was awarded the Order of Lenin, the Order of the Red Banner (four times), the Order of Alexandr Nievskii, the Order of Patriotic War 1st Class and the Order of the Red Star (twice).[46] This is the highest score ever attained by any pilot with any American-made aircraft. The United States did not supply M80 armor-piercing rounds for the autocannons of Soviet P-39s—instead, approximately 1,200,000 M54 high-explosive rounds were supplied, which the Soviets used for air-to-air combat and against soft ground targets. The VVS did not use the P-39 for tank-busting duties.[47][page needed] A total of 4,719 P-39s were sent to the Soviet Union, accounting for more than one-third of all U.S. and UK-supplied fighter aircraft in the VVS, and nearly half of all P-39 production.[48]
Airacobra Soviet losses in 1941-45 were of 1,030 aircraft (49 in 1942, 305 in 1943, 486 in 1944 and 190 in 1945).[50]
Australia
In early 1942, the Royal Australian Air Force (RAAF), experiencing Japanese air raids on towns in northern Australia, found itself unable to obtain British-designed interceptors or sufficient numbers of P-40s. US Fifth Air Force squadrons in Australia were already receiving the brand new P-39D-1.[51] Consequently, in July 1942, older USAAF P-39s, which had been repaired at Australian workshops, were adopted by the RAAF as a stop-gap interceptor. Seven P-39Ds were sent to No. 23 Squadron RAAF at Lowood, Queensland. Later, seven P-39Fs were operated by No. 24 Squadron RAAF at Townsville. In the absence of adequate supplies of P-39s, both squadrons also operated Wirraway armed trainers. However, neither squadron received a full complement of Airacobras, or saw combat with them. The home air defence role was filled first by P-40s, followed by Spitfires. Plans to equip two more squadrons with P-39s were also abandoned. 23 and 24 Squadrons converted to the Vultee Vengeance in 1943.
France
In 1940, France ordered P-39s from Bell, but because of the armistice with Germany they were not delivered. After Operation Torch, French forces in North Africa sided with the Allies, and were re-equipped with Allied equipment including P-39Ns. From mid-1943 on, three fighter squadrons, the GC 3/6 Roussillon, GC 1/4 Navarre and GC 1/5 Champagne, flew these P-39s in combat over the Mediterranean, Italy and Southern France. A batch of P-39Qs was delivered later, but Airacobras, which were never popular with French pilots, had been replaced by Republic P-47 Thunderbolts in front line units by late 1944.
Italy
In June 1944, the Italian Co-Belligerent Air Force (ICAF) received 170 P-39s, most of them -Qs, and a few -Ns (15th USAAF surplus aircraft stored in Napoli-Capodichino airfield) and also at least one -L and five -Ms. The P-39 N (without the underwing fairing for 12.7 machine guns) had engines with about 200 hours; a little newer than the P-39Q engines with 30–150 hours. A total of 149 P-39s would be used: the P-39N for training, while more modern Qs were used in the front line. In June–July 1944, Gruppi 12°, 9° and 10° of 4° Stormo, moved to Campo Vesuvio airstrip to re-equip with the P-39s. The site was not suitable and, in three months of training, 11 accidents occurred, due to engine failures and poor maintenance of the base. Three pilots died and two were seriously injured. One of the victims, on 25 August 1944, was the "ace of aces", Sergente Maggiore Teresio Martinoli.[52] The three groups of 4° Stormo were first sent to Leverano (Lecce) airstrip, then in mid-October, to Galatina airfield. At the end of the training, eight more accidents occurred. Almost 70 aircraft were operational, and on 18 September 1944, 12° Group's P-39s flew their first mission over Albania. Concentrating on ground attack, the Italian P-39s proved to be suitable in this role, losing 10 aircraft to German flak in over 3,000 hours of combat.[53] By 8 May 1945, at the end of the war, 89 P-39s were still at the Canne airport and 13 at the Scuola Addestramento Bombardamento e Caccia (Training School for Bombers and Fighters), on Frosinone airfield. In 10 months of operational service, the 4° Stormo had been awarded with three Medaglia d'Oro al Valore Militare "alla memoria".[54]
Portugal
Between December 1942 and February 1943, the Aeronáutica Militar (Army Military Aviation) obtained aircraft operated by the 81st and the 350th Fighter Groups originally dispatched to North Africa as part of Operation Torch. Due to several problems en route, some of the aircraft were forced to land in Portugal and Spain. Of the 19 fighter aircraft that landed in Portugal, all were interned and entered service that year with the Portuguese Army Military Aviation.[55] Though unnecessary, the Portuguese Government paid the United States US$20,000 for each of these interned aircraft as well as for one interned Lockheed P-38 Lightning.[56] The US accepted the payment, and gave as a gift four additional crates of aircraft, two of which were not badly damaged, without supplying spares, flight manuals or service manuals.[56] Without proper training, incorporation of the aircraft into service was plagued with problems, and the last six Portuguese Airacobras that remained in 1950 were sold for scrap.
Postwar
In 1945, Italy purchased the 46 surviving P-39s at 1% of their cost but in summer 1946 many accidents occurred, including fatal ones. By 1947, 4 Stormo re-equipped with P-38s, with P-39s sent to training units until the type's retirement in 1951. Only a T9 cannon survives today at Vigna di Valle Museum.[53]
Racing Airacobras
The Airacobra was raced at the National Air Races in the United States after World War II. Famous versions used for racing included the twin aircraft known as "Cobra I" and "Cobra II," owned jointly between three Bell Aircraft test pilots, Chalmers "Slick" Goodlin, Alvin M. "Tex" Johnston, and Jack Woolams. These craft were extensively modified to use the more powerful P-63 Kingcobra engine and had prototype propeller blades from the Bell factory. "Cobra I" with its pilot, Jack Woolams, was lost in 1946, over the Great Lakes while he was flying from the National Air Races in Cleveland, Ohio back to the factory to get a fresh engine. The "Cobra II" (Race #84) flown by famed test pilot "Tex" Johnston, beat out P-51 Mustangs and other P-39 racers, which were the favorites, to win the 1946 Thompson Trophy race. Cobra II raced again in the 1947 Thompson Trophy race, finishing 3rd. It raced yet again in the 1948 Thompson trophy race, but was unable to finish due to engine difficulties. Cobra II did not race again and was destroyed on 10 August 1968 during a test flight prior to a run on the world piston-engine speed record, when owner-pilot Mike Carroll lost control and crashed. Carroll died and the highly-modified P-39 was destroyed. Mira Slovak's "Mr. Mennen" (Race #21) P-39Q Airacobra was a very fast unlimited racer; a late arrival in 1972 kept this little 2,000 hp (1,491 kW) racer out of the Reno races, and it was never entered again. Its color scheme was all white with "Mennen" green and bronze trim. It is now owned and displayed by the Kalamazoo Air Zoo. The P-39Q (former USAAC serial no. 44-3908/NX40A), is painted as a P-400, "Whistlin' Britches."
Variants
XP-39
XP-39-BE
Bell Model 11, one prototype 38-326 first flown 6 April 1939 . Powered by an Allison V-1710-17 (E2) engine (1,150 hp/858 kW) fitted with a B-5 two-stage turbosupercharger. Provision was made for two .50 in (12.7 mm) machine guns in the forward fuselage and one 25 mm (.98 in) cannon but aircraft remained unarmed. Later converted to XP-39B.
YP-39
YP-39
Bell Model 12, service test version, V-1710-37 (E5) engine (1,090 hp/813 kW). First two aircraft delivered with armament, the remained with a M4 37 mm (1.46 in) autocannon with 15 rounds, 2 × .50 in (12.7 mm) machine guns with 200 rpg, and 2 × .30 in (7.62 in) machine guns with 500 rpg in the nose. wider vertical tail than XP-39B. 12 completed with the first flying 13 September 1940.
YP-39A
One intended to have a high-altitude V-1710-31 engine (1,150 hp/858 kW), but was delivered as a regular YP-39.
XP-39B
XP-39B
One conversion first flown 25 November 1939. Streamlined XP-39 based on NACAwind tunnel testing resulting in revised canopy and wheel door shape, oil and radiator intakes moved from right fuselage to wing roots, fuselage increased length (by 1 ft 1 in, to 29 ft 9 in) and decreased wingspan (by 1 ft 10 in, to 34 ft). Turbosupercharger replaced with single-stage geared supercharger, Allison V-1710-37 (E5) engine (1,090 hp/813 kW), carburetor air intake moved to fuselage behind canopy.
P-39C
P-39C-BE assigned to the 40th PS / 31st PG at Selfridge Field
P-39C
Bell Model 13, first flown in January 1941 it was the first production version, identical to YP-39 except for V-1710-35 engine (1,150 hp/858 kW). Armed with 1 × 37 mm (1.46 in) cannon, 2 × .50 in (12.7 mm) & 2 × .30 in (7.62 mm) machine guns in the nose. Aircraft lacked armor and self-sealing fuel tanks. Twenty produced out of an order of 80 the remainder were redesignated P-39D
Airacobra I
Airacobra I
Bell Model 13, Royal Air Force designation for three P-39Cs sent to United Kingdom England for testing.
Airacobra IA
Bell Model 14. Briefly named Caribou. V-1710-E4 (1,150 hp/858 kW) engine, 1 × 20 mm (.79 in) cannon with 60 rounds & 2 × 0.50 in (12.7 mm) machine guns were mounted nose and four 0.303 in (7.7 mm) machine guns were mounted in the wings. IFF set removed from behind pilot. note: the designation IA indicates direct purchase aircraft; 675 built. The USAAF operated 128 former RAF aircraft with the designation P-400.
P-39D
P-39D-BE
Bell Model 13, production variant based on the P-39C with 245 lb (111 kg) of additional armor, self-sealing fuel tanks. Armament increased to 1 × 37 mm/1.46 mm cannon (30 rounds), 2 × .50 in/12.7 mm (200 rpg) and 4 × wing mounted .30 in/7.62 mm (1,000 rpg) machine guns; 60 Produced.
P-39D-1
Bell Model 14A, production variant fitted with a M1 20 mm (.79 in) M1 cannon. Specifically ordered for delivery under Lend-Lease; 336 produced
P-39D-2
Bell Model 14A-1, production variant with a V-1710-63 (E6) engine (1,325 hp/988 kW) restored the 37 mm (1.46 in) cannon, provisions for a single 145 gal (549 l) drop tank or maximum 500 lb (227 kg) bomb under the fuselage; 158 produced.
P-39D-3
26 conversions from P-39D-1 to Photo Reconnaissance Configuration; K-24 and K-25 camera in rear fuselage, extra armor for oil coolers
P-39D-4
11 conversions from P-39D-2 to Photo Reconnaissance Configuration. Same modifications as D-3 aircraft.
XP-39E
XP-39E
Bell Model 23. three P-39Ds modified for ground and flight testing first flown 21 February 1942.[57] Intended for Continental I-1430-1 engine with (2,100 hp/1,566 kW) actually flown with Allison V-1710-47 (1,325 hp/988 kW) engine. Airframes were used to test various wing and different vertical tail surfaces. Fuselage was lengthened by 1 ft 9 in (53 cm). Used in the development of the P-63. The production variants, with the Continental engines were to be redesignated as P-76; there was no Bell XP-76 as such.[57]
P-39F
P-39F-1
Bell Model 15B, production variant with three-bladed Aeroproducts constant speed propeller, 12 exhaust stacks; 229 built.
TP-39F-1
One P-39F converted as a two-seat training version with additional cockpit added in nose— no armament.
P-39F-2
27 conversions from P-39F-1 with additional belly armor and cameras in rear fuselage.
P-39G
P-39G
Bell Model 26, 1800 order and intended to be a P-39D-2 with an Aeroproducts propeller. Due to modifications during production no P-39G were actually delivered. Instead, these aircraft were designated P-39K, L, M and N.
P-39H
Designation not used
P-39J
P-39J
Bell Model 15B, a P-39F with V-1710-59 (1,100 hp/820 kW) engine with automatic boost control,; 25 built.
P-39K
P-39K-1
Bell Model 26A, a P-39D-2 with Aeroproducts propeller and V-1710-63 (E6) (1,325 hp/988 kW) engine. Vents added to nose; 210 built.
P-39K-2
Six conversion from P-39K-1 with additional belly armor and cameras in rear fuselage.
P-39K-5
One conversion with a V-1710-85 (E19) engine to serve as a P-39N prototype
P-39L
P-39L-1BE 44-4673 Lend-Lease to USSR
P-39L-1
Bell Model 26C, a P-39K with Curtiss Electric propeller, revised nose gear for reduced drag, provision for underwing rockets; 250 built.
P-39L-2
Eleven conversion from P-39L-1 with additional belly armor and cameras in rear fuselage.
P-39M
P-39M-1
Bell Model 26D, variant with a 11 ft 1 in Aeroproducts propeller, V-1710-67 (E8) (1,200 hp/895 kW) engine with improved high-altitude performance at the expense of low-altitude performance, 10 mph (16 km/h) faster than P-39L at 15,000 ft (4,600 m). Note: some P-39M-1BE were delivered with the V-1710-83 (E18) engine; 240 built.
P-39N
P-39N
Bell Model 26N, originally part of the P-39G order. V-1710-85 (E19) (1,200 hp/895 kW) engine. Aeroproducts propeller (10 ft 4 in diameter) & different propeller reduction gear ratio. Starting with the 167th aircraft, propeller increased to 11 ft 7 in & internal fuel reduced from 120 gal (454 l) to 87 gal (329 l); 500 built.
P-39N-1
Variant with internal changes to adjust center of gravity when nose guns were fired; 900 built.
P-39N-2
128 P-39N-1 converted with additional belly armor and cameras in rear fuselage.
P-39N-3B
35 P-39N converted with additional belly armor and cameras in rear fuselage.
P-39N-5
Variant with armor reduced from 231 lb (105 kg) to 193 lb (88 kg), Armor plate replaced the bulletproof glass behind the pilot, SCR-695 radio was fitted, and a new oxygen system was installed; 695 built.
P-39N-6
84 P-39N-5 converted with additional belly armor and cameras in rear fuselage.
P-39P
Not used
P-39Q
The final production variant last one built in August 1944.
P-39Q-1
Bell Model 26Q, variant with wing-mounted 0.30 in (7.62 mm) machine guns replaced with a single 0.50 in (12.7 mm) with 300 rounds of ammunition in a pod under each wing. Armor increased to the original 231 lb (105 kg) of armor of the P-39N-1BE; 150 built.
P-39Q-2
Five P-39Q-1s modified to carry cameras for photographic reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
Production variant with reduced armor (193 lb/88 kg), fuel capacity increased (110 gal/l). Type A-1 bombsight adapters added; 950 built.
TP-39Q-5
One conversions to a two-seat training variant with additional cockpit added in nose - no armament. Enlarged tail fillet and a shallow ventral fin added.
P-39Q-6
148 P-39Q-5s modified to carry cameras for photographic reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-10
Variant with increased armor (228 lb/103 kg), fuel capacity increased (120 gal/454 l). Automatic Boost controls added and Throttle & RPM controls were coordinated. Winterization of oil systems and rubber mounts added to the engines; 705 built.
P-39Q-11
Eight P-39Q-10s modified to carry cameras for photographic reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-15
Production variant with reinforced inclined deck to prevent .50 in (12.7 mm) machine gun tripod mounting cracking, bulkhead reinforcements to prevent rudder pedal wall cracking, a reinforced reduction gearbox bulkhead to prevent cowling former cracking, and repositioning of the battery solenoid. Oxygen system reduced from four bottle to only two; 1,000 built.
P-39Q-20
Production variant with minor equipment changes. The underwing 0.50 in (12.7 mm) machine gun pods were sometimes omitted in this version; 1,000 built.
P-39Q-21
109 P-39Q-20 fitted with a four-bladed Aeroproducts propeller.
RP-39Q-22
12 P-39Q-20s converted to two-seat trainers .
P-39Q-25
Production variant similar to the P-39Q-21 but with a reinforced aft-fuselage and horizontal stabilizer structure; 700 built.
P-39Q-30
Production variant that reverted back to the three-bladed propellor; 400 built.
XTDL-1
United States Navy designation for two P-39Qs used as target drones. Assigned to NAS Cape May for test work. Later redesignated F2L-1K.
Other
P-45
The P-45 was the initial designation of the P-39C or Model 13.
2 x .50 cal (12.7 mm) machine guns. 200 rounds per nose-gun
4 x .30 cal machine guns, wing mounted. 300 per wing-pod
Bombs: Up to 500 lb (230 kg) of bombs externally
Notable appearances in media
The P-39 Airacobra is featured in the Russian movie Peregon (Transit) (2006) dealing with Lend Lease aircraft in transit to Russia.[76]
The P-39 is also featured in numerous shots in the wartime American movie "Air Force" (124 Min.), an Oscar-winning, propaganda-oriented movie directed by Howard Hawks, released by Warner Brothers in 1943.
Unknown
United Kingdom
United States
