The P-39 Airacobra was a single-seat fighter flown by the United States Army Air Corps in World War II. The Airacobra was an innovative design, but suffered from poor performance at high altitudes. Many were exported to foreign countries, including the Soviet Union.
The P-39, Bell Aircraft’s most successful fighter, sported a number of new design features for the time, including tricycle landing gear and an engine mounted behind the cockpit. Its most well-known aspect was a 37 mm cannon mounted in the nose and fired through the propeller hub. In fact, the beginning of the fighter can be traced to a demonstration of the T-9 37 mm gun by the American Armament Corporation in early 1935. Bell executives present were so impressed by what they saw that they instigated the design of an aircraft that could fire the gun through the propeller hub. The position of the big gun meant that the engine had to be moved to the middle rear of the plane, and this left room for a nose wheel.
The new plane first flew in April 1938, and went into mass production in August 1939.
The P-39 was powered by an Allison, 1325 hp, liquid-cooled engine. However, the turbosupercharger was removed in the production models, hampering their performance at high altitude. Top speed was 380 mph, and range was 1475 miles (with a centerline drop tank). In addition to the cannon, armament consisted of two heavy machine guns in the nose and two or four machine guns in the wings. 
The P-400 was a variant built for the RAF, with a 20 mm gun in the propeller hub. However, after a short period of operation, the RAF discovered that the fighter was not suitable for their purposes. The USAAF took them back in late 1942, sending them to North Africa and the Pacific. Most of the Airacobras had never even been taken out of their crates before being returned. Several P-400s were also sent to the Soviet Union.
American P-39s were most prominent in the first year of the Pacific war, partly because Airacobras and P-40s were the only planes available in the first months. They were used mainly in the ground attack role, although they could hold their own in air combat at low altitude. The nose cannon was slow-firing and often jammed, but when it hit, it was devastating to the lightly armored Japanese planes.
When the war began and the Japanese forces swept south towards Australia, P-39s were rushed into action. In April of 1942, Airacobras of the 8th Pursuit Group were deployed on the front line in New Guinea, and their first combat mission was on April 30. 13 P-39s, led by ace and veteran of the Philippines campaign Boyd “Buzz” Wagner, performed an offensive sweep of the Japanese airfields at Lae and Salamaua. The Americans had surprise on their side, and strafing runs took out a fuel dump, radio station, and three seaplanes at anchor. Defending Zeroes responded, and four P-39s and four Zekes were shot down in the melee. Three of the American pilots bailed out safely and eventually made their way back to base. Three of the Zeros were downed by Wagner himself.
In May, P-39s were involved in the defense of Port Moresby, downing almost twenty of the enemy while suffering heavy losses. P-39s saw heavy action through the rest of 1942, mainly used to provide air support to Allied forces.
By 1943, the Allies were on the offensive in New Guinea. At the end of January, the USAAF had moved the 40th and 41st P-39 squadrons to an airfield Wau, just a few miles away from the Japanese base at Lae, and the Japanese did everything they could to bomb Wau out of existence. Airacobra pilots had more experience by then, and were able to fight the enemy under circumstances more favorable to them, resulting in several victories. On the morning of February 6, Japanese bombers arrived over the American airstrip, and in a fifteen minute battle, defending Airacobras downed one Ki-21 bomber and eleven Ki-43 Oscar fighters for no loss. Four more Japanese fighters were downed for no loss in further fighting that afternoon. Commander of the Fifth Air Force General George Kenney was elated with the results, but downplayed them in press releases out of fear of being accused of overclaiming.
By the beginning of 1944, the only Airacobras left in the theater were specialized models used for photo-reconnaissance. All other units had been re-equipped with P-38 Lightnings or P-47 Thunderbolts.
In 2004, the wreckage of an American P-39 was discovered deep in the jungle in Fiji. It had crashed, killing the pilot, while on a mission in late April of 1942. The pilot’s remains were returned to the US Air Force.
A squadron of P-400s was the AAF’s first contribution to the Battle of Guadalcanal. The sleek fighters arrived on August 22, 1942. They first saw combat a bare 48 hours later when a group of Val dive bombers attacked Henderson Field. The Airacobras downed one of the escorting Zeros with no losses. Their next combat, on August 30, did not work out as well. The squadron CO downed two Zekes, but four P-400s and their pilots were lost. Because of the Airacobra’s deficiencies at high altitude, the F4F Wildcat fighters flown by Navy and Marine pilots bore the brunt of the air-to-air duties. The P-400s (and later P-39s) did manage to score a few aerial victories, but as in New Guinea, were more often assigned to ground support. After Guadalcanal was secured in early February, P-39s took part in defensive patrols and strikes on neighboring Japanese-held islands. The only American to score five kills in the P-39 and become an Airacobra ace, Lt. William Fiedler, was based on Guadalcanal in this period. He downed two Zeros while on escort missions in early February, and followed this up in June with a Zero and two Vals before he was killed in an accident during a take-off. By mid-1943, all P-39s on Guadalcanal had been replaced, mostly by P-38 Lightnings.
The European Theater
Airacobras were involved in the fighting against the Germans as well. An Iceland-based P-39 assisted in scoring the very first American aerial victory in the European Theater on August 15, 1942. The Airacobra attacked a Focke-Wulf FW-200 maritime bomber, setting it aflame before a P-38 Lightning made a pass and exploded the German plane. The same P-39 pilot shot down a Ju-88 bomber over the Atlantic a month later.
P-39s also served in the North African campaign, mainly performing ground attack missions or patrolling over convoys. They saw little aerial combat, but scored around 20 aerial victories over Africa and the Mediterranean. The P-39 had the same disadvantages as in the Pacific campaign, but in the hands of a good pilot, it could hold its own against the Me-109. Over one hundred Airacobras were lost in the Mediterranean Theater to all causes, mostly groundfire.
Out of a total of over 9500 Airacobras produced, almost 5000 were supplied to the Soviet Union via Lend Lease, and it was in Soviet hands that the plane scored its greatest successes. Air combat on the Eastern Front tended to be at lower altitudes, which minimized the P-39’s disadvantages, and in the right hands, the fighter proved deadly. Over a hundred Russian pilots, including three of the five top scorers, became Airacobra aces, and the highest scoring P-39 pilot ever was Hero of the Soviet Union Gregori Rechkalov, with an even 50 victories with the American plane, including several Bf-109s.
With its 37 mm cannon, the P-39 was highly effective against ground targets as well, although, contrary to popular belief, it was not a tank-buster.
- The World’s Great Fighters: From 1914 to the Present Day, by Robert Jackson, Amber Books, 2001
- The Illustrated Encyclopedia of Combat Aircraft of World War II, by Bill Gunston, Salamander Military Press, 1990
- P-39 Airacobra Aces of World War 2, by George Mellinger and John Stanaway, Osprey Publishing, 2001
- Fiji hands over lost pilot’s remains
- Some sources claim it was a P-40 Warhawk instead.
- Soviet P-39 Aces
- Airacobra or Iron Dog?, The Obscure Career of Bell’s P-39 in the Soviet Union