It was in many respects unique — it carried its engine rear of the cockpit and had a powerful 37mm autocannon poking out of its propeller hub.

When the United States entered World War II, the American-built P-39 Aircobra was America’s primary fighter airplane. On paper at least, the P-39 was a very uniquely arranged aircraft with a great amount of potential.

Unlike most airplanes that were designed around their engines, the Aircobra was instead designed around its main armament, a powerful 37mm autocannon integrated inside the fuselage along the airframe’s center line, which saw the powerful gun’s barrel poking out through the propeller hub. Though certainly a powerful air-to-air weapon, a small 30-round capacity, as well as the weapon’s slow three-round per second rate of fire, limited the autocannon’s usefulness.

Another interesting feature, necessitated by the forward-mounted cannon, was the P-39’s engine, which was located near the center of the airplane’s fuselage behind the cockpit. This contrasted sharply with most of the other fighters of the era, which mounted engines forward in the pane’s nose.

Mounting the engine in the fuselage body rather than the nose had several advantages: the pilot was better protected from rear and the engine was better protected from ground fire. This arrangement also gave the P-39 a much smoother, more streamlined profile than many other fighters.

The drawbacks to the design were several. Due to engine deficiencies, the P-39 was quite sluggish at higher altitudes. The engine was also more vulnerable to fire from a chasing airplane, and in addition, the 37mm autocannon—though powerful—was somewhat unreliable.

Despite the Aircobra’s rather lackluster performance at high altitude, the unique fighter excelled on one of World War II’s bloodiest battlefields: the Eastern Front.

While the Royal Air Force and the United States Army Air Forces depended on high-performance especially at high altitudes to face off against German bombers and escort fighters, a large part of the Eastern Front’s fighting took place at lower altitudes and at somewhat slower speeds. In this environment, the Aircobra excelled—with Soviet pilots aboard.

One Soviet Aircobra pilot sung the airplane’s praises, highlighting both pilot comfort as well as the plane’s ergonomics, stating:

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 seemed a bit small after the P-40, but it 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. If you wanted to piss, pull the tube out from under the seat and go for it! It even had orders for pens and pencils.

The armored glass was very strong, extremely thick. The armor on the back of the seat 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.

At altitudes below around 12,000 feet, the Aircobra excelled, able to take on Germany’s Stuka dive-bombers and Messerschmitt Bf 109s with some success.

Though not the most successful American fighter, in Soviet hands, the P-39 Aircobra was a resounding success.

Caleb Larson is a Defense Writer with The National Interest. He holds a Master of Public Policy and covers U.S. and Russian security, European defense issues, and German politics and culture.

Image: Wikimedia Commons.