P-39 Airacobra Totally Explained

Everything about P-39 Airacobra totally explained

The Bell P-39 Airacobra was one of the principal American fighter aircraft in service at the start of World War II. 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, although the type was used with great success by the Soviet Air Force. In the P-39, Soviet pilots scored the highest number of individual kills attributed to any U.S. fighter type. Together with the derivative P-63 Kingcobra, these aircraft would be the most successful mass-produced, fixed-wing aircraft manufactured by Bell.

Design and development

In 1937, the United States Army Air Corps issued a specification for a new fighter via Circular Proposal X-608. It was a request for a high-altitude interceptor aircraft having "the tactical mission of interception and attack of hostile aircraft at high altitude". Specifications called for a maximum airspeed of at least 360 miles per hour (580 km/h) at altitude, and a climb to 20,000 feet (6100m) within 6 minutes; the toughest set of specifications USAAC had presented to that date. Other competing designs included the Curtiss P-40, an outgrowth of a previous design, and the Lockheed P-38, which utilized a complex twin-engine twin boom configuration. Although Bell's limited fighter design work had previously resulted in the unusual Bell YFM-1 Airacuda, the Model 12 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. 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 cannon mounted in a conventional manner 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.
   A secondary benefit of the mid-engine arrangement was to create a smooth and streamlined nose profile. The weight distribution necessitated a tricycle undercarriage, a first among American fighters, concurrent with the Lockheed XP-38. 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 pilot concern 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; both were deleted for production. The production P-39 retained a single-stage, single-speed supercharger with a critical altitude (above which performance declined) of about 12,000 ft.
   The XP-39 made her maiden flight on 6 April 1938 at Wright Field, Ohio, achieving 390 mph at 20,000 ft. (630 km/h at 6,100 m), reaching this altitude in only five minutes. The Army ordered twelve YP-39s (with only a single-stage, single-speed supercharger) for service evaluation and on advice from NACA,
   After completing service trials, and originally designated P-45, a first order for 80 aircraft was placed 10 August 1939; the designation would revert before deliveries began. A long transmission tunnel passed through the fuselage, under the cockpit, and was linked to the three bladed propeller. The radiator was located in the fuselage.
   In September 1940, Britain ordered 386 P-39Ds (as the Model 14), of 675 in all, differing in the 37 mm being replaced by a 20 mm Hispano and the 6x0.3 by .303 (7.7 mm). These began equipping 601 Squadron in September 1941, and were promptly recognized as having inadequate rate of climb and performance at altitude; only 80 joined the RAF (only 601 Squadron being outfitted), over 250 being transferred to the Soviets, about 200 repossessed by the Army after Pearl Harbor, and some 200 sent to Eighth Air Force in 1942 (the Army models being designated P-400). 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. 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. On the other hand it was considered effective for low level fighter and ground attack work. Problems with gun and exhaust flash suppression and compass were fixable. 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 in March 1942, it 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 testing, until it was scrapped on the recommendation of a visiting Bell test pilot in March] 1946.

U.S.

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 . 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. It often proved 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.
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 number one foe that claimed the most lives, however, wasn't 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. By June they were scoring with P-47 Thunderbolts and then in P-51 Mustangs in July 1944.
Only one U.S. pilot, Lt. Bill Fiedler, became an ace in a P-39; however, many U.S. aces scored one or two of their kills using the P-39.

USSR

The most successful use of the P-39 was in the hands of the Soviet Air Force (VVS). The tactical environment of the Eastern Front didn't demand the extreme high-altitude operations that the RAF and 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. It was common for the Soviet pilots to remove the wing guns and rely only on the cannon and nose machine guns as armament. The P-39 was well liked by VVS pilots. Contrary to popular misconception that the P-39 wasn't suitable for air-to-air combat and was instead, because of its large cannon, relegated to ground attack or "tank busting," the P-39 was used extensively by the Soviets for air-to-air combat against a variety of German aircraft, including Bf 109s, FW 190s, Ju 87s, and Ju 88s. The second-highest scoring Allied ace, Aleksandr Pokryshkin, flew the P-39 from late 1942 until the end of the war (though rumours exist that he changed late 1944 to a P-63 Kingcobra); his unofficial score in the Airacobra stands at nearly 60 Luftwaffe aircraft. His wingman, Grigori Rechkalov, scored 57 victories with the P-39. This is the highest score ever gained by any pilot with any U.S.-made aircraft. The usual nickname for the Airacobra in the VVS was Kobrushka, "little cobra", or Kobrastochka, "dear little cobra". A total of 4719 P-39s were sent to the Soviet Union, accounting for more than one-third of all U.S. and U.K.-supplied fighter aircraft in the VVS, and nearly half of all P-39 production.

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. 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 numerous P-39s to Bell, but because of the armistice with Germany they were not delivered. However, 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 P-47 Thunderbolts in front line units by late 1944.

Italy

In June 1944, the Italian Co-Belligerent Air Force (ICAF) 223° Group received approximately 150 P-39s, almost all -Ns and -Qs, but also at least one -L and five -Ms. The training of 4° Stormo pilots began on P-39Ns (with over 200 hours on them), while more modern Qs were used in the front line. The three groups of 4° Stormo trained at a small and poorly-maintained airfield near Vesuvio, then were sent to Galatina airfield in fall 1944. At least 19 training accidents occurred; among the victims on 25 August 1944 was Teresio Martinoli, a 22-victory ace with four years of combat experience.
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 and accumulating over 3,000 hours of combat, losing ten aircraft to German flak, the Italian P-39s proved to be suitable in this role.

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 — the first examples to enter service were five P-39s from the 81st Fighter Group, which landed on 27 December 1942 at Lisbon Airport. |+ P-39 interned by Portugal (1942—1943) |- ! ignore="text-align: center; background: #aacccc;"|Date ! ignore="text-align: center; background: #aacccc;" title="Quantity"|Quantity ! ignore="text-align: center; background: #aacccc;"|Fighter Group |- | 27 December 1942 || 5 || 81st |- | 15 January 1943 || 2 || 81st |- | 15 January 1943 || 9 || 350th |- | 8 February 1943 || 1 || 350th |- |}
   Although the obtainment of this aircraft was due to their landing in Portugal, the Portuguese Government requested the purchase of the aircraft that had until 1943 been interned. On 26 April 1943, the United States authorized the sale for $20,000 each of the 16 Airacobras and one P-38 Lightning which were intact, and to give as a gift four crates of aircraft, two of which were not badly damaged. However, the United States declined to supply spares. The fact that these aircraft were interned during flight missions, and that no flight or maintenance manuals were bought or available, never allowed a correct transition for the pilots coming from another aircraft. A check-list was recovered from one of the aircraft, but that was incomplete and not totally correct, so provided some help but still severe difficulties were felt in the adaptation of pilots to the aircraft. The arrival of American mechanics at the Lajes Air Base eased the maintenance problems, but still any type of documents and technical manuals were never handed over to Portuguese crews.
   Because of the previous stated reasons, the start of these aircraft activity was marked with accidents, dut mainly to deficient engine handling. |+Portuguese P-39 accidents log book |- ! ignore="text-align: center; background: #aacccc;"|Aircraft ! ignore="text-align: center; background: #aacccc;"|Date ! ignore="text-align: center; background: #aacccc;"|Notes |- | Airacobra 301 || 15 August 1943 || |- | Airacobra 304 || 16 August 1943 || Near Ota, causing the death of the pilot, 1st Sergeant Augusto Alves Ferreira |- | Airacobra 309 || 26 August 1943 || |- | Airacobra 312 || 8 February 1944 || During a training flight |- | Airacobra 317 || 25 April 1946 || |- |} Other accidents are known in which many of the aircraft were not repairable, as one case in which the pilot lost control when rolling too fast and crashed against two other aircraft; and two other aircraft that had to make emergency landings due to engine failure (one at Póvoa de Varzim, and the other at Costa da Caparica). In 1944, the Portuguese P-39 saw a peak of activity when 14 Airacobras, divided in two flights of seven aircraft each, participated in various combined armed forces exercises at Ota. Due to the recurring problem of contamination of the cockpit with carbon monoxide when the machine guns were fired, with the fact that the weapons had a difficult access for maintenance, and had many malfunctions, led to the low or non-existent use of them.
   The service life of the P-39 in Portugal wasn't a very long one, and the last six Airacobras that remained until the aircraft retirement 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, even fatal ones. By 1947, 4 Stormo re-equipped with P-38s, and P-39s were sent to training units until retirement in 1951. Only a T9 cannon survives today at Vigna di Valle Museum.
   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 owing to engine difficulties. Cobra II didn't race again and was destroyed on August 10, 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 perished and the highly-modified P-39 was wrecked.
   Mira Slovak's "Mr. Mennen" (Race #21) P-39Q Airacobra was a very fast unlimited racer - a late arrival in 1972 kept this little 2000+ hp 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."
   In 1942, an P-39 Airacobra crashed in Fiji, but wasn't found until a local pig farmer discovered the wreck in 2004. The pilot's body was also found and sent to Hawaii for identification. Personal items were recovered at the site.
   A number of P-39s are still in existence of which three are still flying. The Commemorative Air Force flies a Bell P-39 Airacobra painted in the markings and colors of the 350th Fighter Group, which consisted of the 345th, 346th and 347th Fighter Squadrons operating P-39s in North Africa and Italy. At one time, the Airacobra was painted in Russian colors and markings. Bell P-39Q-6-BE USAAF, serial no. 42-19993, "Brooklyn Bum– 2nd" is now at the Fighter Collection in Duxford, UK. The Smithsonian's National Air and Space Museum has P-39Q-15BE, serial no. 44-2433 on display. Keski-Suomen Ilmailumuseo at Tikkakoski, Finland, has one restored P-39Q Airacobra, "White 26", on static display. The aircraft is originally a Soviet lend-lease plane, shot down and captured by Finnish troops in World War Two. It has been restored in the original wartime camouflage and markings.

Popular culture

Introduction to the P-39 (1942) (External Link) Bell wartime training film (38 min) intended for military pilots examining flight techniques, cockpit layout and armament.
Flying the P-39 (1943) (External Link) Bell Training Film No. A.F. - 110 (23 min) demonstrating techniques for piloting the P-39 including aerobatics and strafing.
The P-39 Airacobra is featured in the Russian movie Peregon (Transit) (2006) dealing with Lend Lease aircraft in transit to Russia.

Variants

XP-39: first prototype, unarmed ;YP-39: service test version, V-1710-37 (E5) 1,090 hp engine, 12 built

YP-39A: intended to have a high-altitude V-1710-31 engine (1,150 hp) but delivered as a regular YP-39, one built. ;XP-39B: streamlined XP-39 based on NACA wind tunnel testing resulting in revised canopy and wheel door shape, oil and radiator intakes moved from right fuselage to wing roots, 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 rated to .

P-39C: first production version, identical to YP-39 except for V-1710-35 1,150 hp engine. Armed with 1x 37 mm cannon, 2x .50 cal and 2x .30 cal machine guns. First aircraft lacked armor and self-sealing fuel tanks. ;P-39D: 245 lb of additional armor, self-sealing fuel tanks. Armament increased to 1x 37 mm cannon (30 rounds), 2x .50 cal (200 rounds/gun) and 4x .30 cal (1,000 rounds/gun) machine guns. Provisions for a single 250-lb, 325-lb, or 500-lb bomb under the fuselage.

P-39D-1: Lend-Lease version, Hispano 20 mm cannon instead of the 37 mm cannon ;P-39D-2: Lend-Lease version, upgraded V-1710-63 (E6) engine with 1,325 hp; restored the 37 mm cannon; provisions for a single 145 US gallon drop tank under the fuselage.

Bell Model 14: export version, ordered by France but not delivered. ;P-400 Airacobra I: P-39D for Royal Air Force, briefly called :Caribou:; Hispano 20 mm cannon (60 rounds) instead of the 37 mm cannon. A total of 200 were requisitioned by USAAF after Pearl Harbor; most were used for training, but some saw service in the Southwest Pacific.

XP-39E: intended for Continental I-1430-1 engine with 2,100 hp; see Bell XP-76 ;P-39F-1: Aeroproducts constant speed propeller

P-39F-2: field conversion of P-39F-1 with additional belly armor and cameras in rear fuselage ;TP-39F: Two-seat training version, built in small numbers.

P-39G: 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-39J: P-39F with V-1710-59 1,100 hp engine with automatic boost control

P-39K: P-39D-2 with Aeroproducts propeller and V-1710-63 (E6) 1,325 hp engine; one aircraft designated P-39K-5 and fitted with a V-1710-85 (E19) engine to serve as a P-39N prototype ;P-39L: P-39K with Curtiss Electric propeller, revised nose gear for reduced drag, provision for underwing rockets.

P-39M: 11 ft 1 in Aeroproducts propeller, V-1710-67 (E8) 1,200 hp engine with improved high-altitude performance at the expense of low-altitude performance, ten mph faster than P-39L at . ;P-39N: V-1710-85 (E19) 1,200 hp engine; Aeroproducts propeller enlarged from 10 ft 4 in to 11 ft 7 in starting with 167th aircraft. The P-39N-5 had reduced armor.

P-39Q: wing-mounted 0.30 cal machine guns replaced with a single 0.50 cal with 300 rounds of ammunition in a pod under each wing. These wing guns were often removed on Soviet aircraft. P-39Q-21 had a four-bladed Aeroproducts propeller. The P-39Q-30 reverted to a three-bladed propeller because the four-bladed unit worsened directional stability. ;RP-39Q: Two-seat training version, built in small numbers.

P-45: The P-45 was the initial designation of the P-39C or Model 13. ;F2L: Seven P-39s were supplied to the U.S. Navy to be used as target drones.

XFL-1 Airabonita: One prototype for the U.S. Navy. ;A-7: Proposed radio-controlled target drone, never built.

TDL: Radio-controlled target drone for the U.S. Navy

Operators

: RAAF ;:

: ;: (two aircraft only)

: Esquadrilha Airacobra (Airacobra Squadron), later renamed Esquadrilha 4 (Squadron No. 4) — Aeronáutica Militar (Army Military Aviation) ;Further Information

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