On April 6th 1938 the prototype Bell P-39 Airacobra lifted off from Wright Field in Ohio for the first time. The P-39 may well be the most under-appreciated American fighter aircraft ever built. This is in large part due to the fact that as World War II unfolded, other more advanced and suitable (read better) fighters made their way to American pilots tasked with defeating Axis machines in the air. That was not the case for allies like Russia, who received thousands of P-39s through the Lend/Lease program and used them to rack up an impressive number of victories over their German opponents. As a ground attack platform and a low-level fighter the P-39 had few equals.
The unusual design of the P-39 placed the liquid-cooled twelve cylinder inline Allison V1710 engine in mid-fuselage behind the pilot, driving the three-bladed propeller via a ten foot long drive shaft. As a result, “car” doors with roll down windows were used to access the cockpit from either side of the aircraft rather than the sliding canopy found on so many of the P-39’s contemporaries. One of the primary performance handicaps of the P-39 was the lack of a turbo-supercharger, which was a liability when operating above 12,000 foot altitudes. A prototype mounted a turbo-supercharger but the associated large intake and exhaust with ducting induced drag and weight penalties on the Airacobra. The production aircraft would be equipped instead with a single-speed, single-stage supercharger after Bell elected to retain the aerodynamic efficiency of the design. It was said that the Bell designers regretted the decision to equip the aircraft with only the supercharger. The Airacobra was also one of the first American fighter aircraft to mount tricycle landing gear.
One reason the P-39 mounted the engine in mid-fuselage was to utilize space in the nose of the fighter for its primary weapon, that 200 pound 90 inch long Oldsmobile T9 37 millimeter cannon which fired through the center of the propeller hub. This allowed for the best possible stability and accuracy when firing the cannon. But like all repeating guns mounted in aircraft, the T9 cannon was limited by minimal space for its meager 30 rounds of ammunition and was prone to jamming when fired as the aircraft maneuvered. Bell designers actually designed the P-39 around the cannon, which was a departure from previous design practice. Two .50 caliber machine guns were mounted in the nose and synchronized to fire through the propeller blades. Wing-mounted .30 and .50 caliber machine guns as well as the ability to carry bombs and drop tanks were also incorporated into the design as it evolved.
The Airacobra was actually designated P-45 during trials. On August 10th 1939 an order for 80 aircraft was placed with Bell but the designation was changed to P-39 before the first deliveries. Experience in European air combat conditions revealed that self-sealing fuel tanks and protective armor (which the original P-39s lacked) were requirements and the P-39 would have to have them. Therefore the first score of P-39C aircraft were deemed unsuitable for combat. The first P-39s to enter service with the United States Army Air Corps (USAAC) were the other 60 P-39Ds equipped with protective armor and self-sealing fuel tanks that equipped the 39th Pursuit Squadron Flying Cobras, part of the 31st Pursuit Group at Selfridge Field in Michigan.
When the USAAC fighter units arrived in the European Theater of Operations (ETO) they were equipped with Supermarine Spitfire Mark Vs instead of P-39s. The reason was simple, and predictable, enough. The P-39’s performance at altitude was simply inferior to the contemporary European fighters. But the P-39 was maneuverable enough, actually capable of out-rolling the Mitsubishi A6M2 Zero, the Grumman F4F Wildcat and F6F Hellcat, and the Lockheed P-38 Lightning at up to 265 miles per hour. Nothing, however, could be done to improve the high altitude performance of the P-39. There just wasn’t any room in the fuselage to incorporate the turbo-supercharger required to make the Airacobra a better high-altitude performer without severe drag penalties.
Britain, starved for additional aircraft after the drain of the Battle of Britain, ordered 386 P-39Ds in September of 1940. The Brit Airacobras had a 20 millimeter cannon mounted in place of the 37 millimeter but in most other respects the P-39s were standard D models. Even though they eventually ordered 675 P-39s (all variants) the British quickly realized that the plane just wouldn’t do what they needed it to do in European air combat against the German Luftwaffe. Used in a single attack against barges in occupied France, the P-39 had a remarkably short run with the Brits. They transferred 202 of the P-39Ds to Russia. The USAAC, also starved for fighter aircraft after the war started, held 200 of the British aircraft back and re-designated them P-400. The British did not protest. Some of these, along with many of the P-39s manufactured by that point, were sent to the Southwest Pacific for service with the 5th Air Force against the Japanese.
The P-39s and P-400s performed their best below 12,000 feet. That was no secret. But the Airacobras were able to hold their own against the vaunted Japanese Zeroes by using the same successful tactics used by the other Allied fighters of the day. Especially effective in the ground attack role, the aircraft served with the Cactus Air Force on Guadalcanal and throughout the Solomons as well as New Guinea. One unintended benefit to the Navy was that derelict P-39s donated their 37 millimeter cannons to quite a few of the P.T. boats operating in the area. But due to the same range and altitude limitations experienced elsewhere, the P-39s were hamstrung in the theater. P-39s saw their first combat on April 30th 1942. Even though it has been said that the Zero was far superior to the P-39, combat records indicate that during the frequent combat between the types that took place during 1942, the P-39 was not strictly outclassed in its element- below 12,000 feet.
Combat involving American P-39s also took place in the Aleutian Islands and the Mediterranean, albeit briefly. The famous 99th Fighter Squadron “Tuskegee Airmen” flew the P-39 for a few weeks in 1944. P-39s were used for maritime patrol of the Mediterranean from North Africa and later Italy. P-39s were also utilized in Hawaii for quite some time as interceptors. Roughly halfway through the war America had relegated the majority of the P-39s to training and coastal reconnaissance roles. P-39 production continued though…because there was still at least one allied nation that wanted every last P-39 they could get their hands on.
The Red Air Force (The Russian words boil down to VVS) received 4,719 P-39s- nearly half of all P-39s produced and a third of the total number of all Allied fighter aircraft supplied to the Russians. The majority of the P-39s used by the Russians were the improved N and Q variants, but that just meant the limitations of the aircraft were offset a bit more by improved systems and armament. The first thing the Russians did to their new P-39s (after dubbing them “Little Cobras”) was remove the wing-mounted machine guns to lighten the airframe and improve its maneuverability. The air war in Russia was tactically different than elsewhere. It was fought primarily below 12,000 feet. The Russians used their P-39s where they performed their best, and they got results. But a common myth holds that the Russians busted tanks with the P-39. Two factors made that a practical impossibility. The first was that they were not supplied with enough of the armor-piercing ammunition for the 37 millimeter cannon to make a living busting tanks. The other reality is that the armor-piercing round itself was not effective against the German tanks of the day. The Russians had plenty of high explosive rounds for their Little Cobras, and they used them with devastating effectiveness against ground targets and German troops. And they shot a few of them at German aircraft too.
Russian VVS pilots operated the P-39 from August of 1942 through to the end of the war. Not commonly known is that the Lockheed P-38 Lightning and the Grumman F6F Hellcat were not the American-built fighters flown by the highest scoring aces of World War II. That distinction belongs to the Bell P-39 Airacobra in the capable hands of several of the top Russian aces. The leading overall Russian ace, Aleksander I Pokryshkin scored 59 total victories. 48 of them were scored in P-39s. The Russian ace with the most kills in P-39s was Gregoriy Rechkalov, who scored 50 of his total 56 kills in P-39s. Five of the top ten Russian aces flew P-39s. Russia produced 28 aces with at least 15 victories and eight of them scored at least 30 victories- an impressive tally no matter what aircraft the pilots were flying. Contrast this with the one and only American P-39 ace (William Fiedler). The last plane shot down by the Luftwaffe was a Russian P-39, and the last Russian aerial victory of the war was scored by a P-39. 1,030 Russian P-39s were lost (to all causes) during World War II. P-39s served with the VVS through 1949. Operators of the P-39 Airacobra include Australia, Free France, Italy, Poland, Portugal, Russia, the United Kingdom, and the USAAC.
When Pearl Harbor was attacked, there were roughly 600 P-39s in service. When Bell stopped building P-39s during August of 1944 in order to more completely focus their attention on their first jet fighter design (The P-59 Airacomet), 9,558 P-39s (all variants) had been produced. There were a passel of variants with changes to engines, propellers, armaments, protective armor configurations, and even cameras to allow the P-39s to perform aerial photo reconnaissance. Just about the only things they didn’t try changing on a P-39 were changes to the rugged construction of the airplane and its single-speed, single stage supercharger. But they did produce a larger cousin, the Bell P-63 King Cobra…but that’s another story.