Airacobra or Iron Dog?

The Obscure Career of Bell's P-39 in the Soviet Union

By Patrick Masell


P-39Q
Official USAF photograph

The P-39 Airacobra made by Bell Aircraft Corporation was produced from 1939 until 1944. It might be called the most controversial U.S. fighter of the Second World War. Embraced by the Soviet Union, shunned by the Western Allies and hounded by myths and falsehoods that distort history's judgement.

There's no doubt that the XP-39 evoked gasps and ahs when it was unveiled at Wright Field on April 6, 1939. The clean, exotic lines of the Airacobra prototype gave it a futuristic look. Just by looking at it one could see the innovations and peculiarities incorporated into Bell's new plane.

The P-39 was one of the first planes to use a tri-cycle landing gear configuration, which eventually would be standard on all fighters. Another feature that didn't catch on was the car-like door to exit the cockpit instead of a sliding canopy. Most notable was the mid-fuselage placement of the engine. This made way for the Colt M4 37mm cannon protruding out of the nose. The powerplant was the Allison V-1710, essentially the same engine as that which powered the XP-38 and XP-40 prototypes. It was equipped with the B-5 turbo-supercharger and rated at 1,150hp. The unarmed and unarmored prototype could reach a stunning speed of over 390mph and could climb to 20,000 feet in five minutes.

Overall, the Airacobra had a high-altitude capability that matched the XP-38. Despite the XP-39's admirable performance the Wright Field engineers felt it had too much drag. To streamline the design the canopy was lowered, the wingspan cut by two feet, and fuselage lengthened by a foot. Most importantly, the turbo-supercharger inlet was reduced in size and moved from the side of the fuselage to a position directly behind the canopy. This meant that the turbo-supercharger had to be replaced by a single stage supercharger. Because of this modification the high-altitude performance dropped dramatically. This, however, wasn't a large concern of the Army Air Corps, whose doctrine of "the bomber always gets through" foresaw no need for high altitude escorts.

The first mass-produced model was the P-39D of 1941. All P-39 models from the D forward were really quite similar. The D-1 temporarily replaced the 37mm cannon with a 20mm cannon. The D-2 model introduced a more powerful 1,325 hp. Allison V-1710-63 engine.

Basic specifications for the P-39D were as follows (taken from The Fighter Aircraft Pocketbook by Roy Cross): Max speed 360 mph at 15,000 ft; Best climb 2,040 ft/min. at 10,300 ft.; Climb to 20,000 ft. 11.7 min.; Range 600 miles at economical cruise; Armament 1-37mm nose cannon, 2-.50 nose m.g., 4-.30 wing m.g.; Span 34 ft. 2 in.; Length 30 ft. 2 in.; Height 11 ft. 10 in.; Wing area 213 sq. ft.; Empty weight 6,300 lbs.; Max weight 9,200 lbs.

The F model of 1942 differed from the D only in detail. A proposed carrier based version of the P-39, the XFL-1, failed its carrier qualification trials and development was abandoned in 1942.

The K and L models of 1943 had V-1710-63 engines and a new propeller. The L also had an improved nose wheel. The M and N models, introduced later in 1943, had V-1710 engines rated at 1,200 hp.

The final, and most numerous, production version was the Q, which replaced the 4-.30 wing guns with two under wing .50 machine guns. The Q-21 and Q-25 variants had a four-bladed propeller. 4,905 P-39Qs were built

Before long orders started coming in for Bell's new plane. France needed fighters to help fend off the Lutwaffe, but like many orders for American equipment, not a single plane was delivered before the France fell to the Germans. Britain accepted the French order, but soon regretted doing so. RAF pilots hated the P-39. Their main gripes were the drop in performance above 20,000 feet, a tendency to spin, and the difficulty to recover from a spin. Also on the list was the short range of 430 miles on internal reserves and 690 miles with drop tanks. They also reported that fumes would fill the cockpit after firing the guns. These flaws were often exaggerated to the point that it seemed impossible for the P-39 to effectively serve as a fighter. However, they did concede that it was the equal of the vaunted Bf-109 below 20,000 feet. Still, the British needed a high-altitude fighter and dumped their P-39s on the USAAC; the rest of the order was cancelled.

The Americans faired even worse with their Airacobras. When the United States was plunged into war with Japan, its primary land-based fighters were the P-40 and P-39. P-39 pilots experienced the same difficulties as the British and also complained that the M4 cannon often jammed.

The air battles of the Pacific were fought at intermediate altitudes, optimal conditions for Bell's fighter. But the American pilots were not facing Bf-109s, but ultra-light and super-agile A6M Zeros and Ki-43 Oscars. The P-39, like every other Allied fighter (including the vaunted Spitfire), could not turn as tight or maneuver as quickly as these nimble Japanese fighters.

Also, the 37mm cannon was not an effective air-to-air weapon. Though it might only take one hit to bring down the fragile Zero, the slow rate of fire and drooping trajectory made that one hit improbable. And not all P-39s had the 37mm cannon; the Airacobras the British handed over to the USAAC had a 20mm cannon in its place. This type was called the P-400. It soon became the joke of the Pacific that a P-400 was a P-39 with a Zero on its tail. But, 37mm or not, the two .50 and four .30 caliber machine guns could still make short work of a Zeke. Perhaps the biggest reasons for the P-39's bad showing in the Pacific were the lack of knowledge about Japanese aircraft, numerical inferiority, and veteran enemy pilots. U.S. pilots found the Airacobra's flaws unforgivable and requested transfers to P-38 units before these problems could be resolved. In the hands of the USAAC the P-39 proved a dismal failure and seemed a perfect candidate for the title "Worst fighter of World War II."

Of the 9,585 examples of the P-39 built before the end of the war, 4,500 (almost half) were given to the USSR. This seems appropriate since Russia was the only country that achieved widespread success with the plane.

Soviet pilots were introduced to the Airacobra beginning early in 1943. They too reported handling problems, primarily spinning. Also, they had trouble using the radio; for many this was the first aircraft they had flown equipped with a radio! These complaints were relatively minor, and overall the Russians were very satisfied with their new acquisition. They praised its low altitude speed and maneuverability, excellent structural integrity, and heavy armament. It should be noted that difficulties with the 37mm and fume infiltration reported by Western flyers were not experienced by their Russian counterparts. From 1943 'til the end of the war the so-called "Iron Dog" enjoyed much success in the hands of its Russian masters.

In the years since World War II, a number of myths have emerged that now are accepted as historical fact. Today it is believed that the P-39 could not have been a competitive fighter. However, Soviet pilots regularly mixed it up with and prevailed against German fighters.

Aerial warfare over the Eastern Front was particularly suited to the Airacobra. There was no long-range, high-level, strategic bombing, only tactical bombing at intermediate and low altitudes. On this battlefield the P-39 matched, and in some areas surpassed, early and mid-war Bf-109s. And it had no trouble dispatching Ju-87 Stukas or twin-engine bombers. Five out of the ten highest scoring Soviets aces logged the majority of their kills in P-39s. In fact, P-39 jockeys filled the number two, three, and four spots: Aleksandr Pokryshkin (59), Aleksandr Gulaev (57), and Grigoriy Rechkalov (56).

However, later in the war updated variants of the Bf-109 and the deadly FW-190 arrived on the Eastern Front. Bell failed to adequately improve its plane's performance to match these threats, probably because newer fighters (including the P-39's successor, the P-63 Kingcobra) made it unnecessary. Though not a match for these new breeds, with a skilled pilot the Airacobra was still capable of holding its own. Also, with American and British bombers constantly attacking German cities and industrial targets, the Luftwaffe was forced to withdraw most of their experienced flyers from the Eastern Front and press them into the defense of the Fatherland. This left the capable German fighters in the incapable hands of relatively unskilled pilots.

Most Western writers claim that the Russians utilized the P-39 primarily in the ground attack role. Though it was competent in this role, that was not the primary mission of Soviet Airacobra pilots. The priorities of the P-39 flyers (and Soviet fighters in general) were:

  1. Protect ground units from enemy aircraft
  2. Escort bombers
  3. Suppress AAA in the area of bombers
  4. Reconnaissance
  5. Free hunt
  6. Attack soft targets (i.e. troops, convoys, supply dumps, railroads, airfields, barges or other small naval craft)
  7. Protect high-value friendly targets (i.e. bridges, amphibious landing forces, reserves, command and control, major cities, etc).

The last major misconception about the P-39 is that it was an effective tank buster. In early August of 1944, while flying over a tank battle in Poland, Alexsandr Pokryshkin told the T-34 unit commander, "Our cannons will not penetrate tank armor." The Colt M4 had a muzzle velocity of only 600 meters per second and a low rating of 1.41 kilograms 'steel on target' per second. Theoretically, it could penetrate the armor of early panzer tanks, but only the top of the hull and turret. By comparison, the NS-37 37mm cannon had a muzzle velocity of 900 m/s and a steel on target rating of 3.06kg, enough to get through all but the Tiger's side or front armor. Also, instead of the M80 AP rounds that were required, the U.S. shipped the Soviets M54 high explosive shells, which were ineffective against tanks. Therefore, the P-39 was not used as a tank destroyer on the Eastern Front.

Bell's P-39 Airacobra was a plane of contradictions. Loathed by the Western Allies, but loved by the Russians, it found a home in the skies above the Soviet Union. Outside of that home however, historians generally accept false information about its performance. This is probably due to the language barrier, Soviet secrecy, and perhaps because it is hard to imagine that the Russians could use the fighter successfully and we could not.




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