The Ilyushin Il-2 (Russian: Илью́шин Ил-2) is a ground-attack plane that was produced by the Soviet Union in large numbers during the Second World War. The word shturmovík (Cyrillic: штурмовик), the generic Russian term for a ground-attack aircraft, became a synecdoche for the Il-2 in English sources, where it is commonly rendered Shturmovik, Stormovik and Sturmovik.
To Il-2 pilots, the aircraft was known by the diminutive "Ilyusha". To the soldiers on the ground, it was called the "Hunchback", the "Flying Tank" or the "Flying Infantryman". Its postwar NATO reporting name was Bark.
During the war, 36,183 units of the Il-2 were produced, and in combination with its successor, the Ilyushin Il-10, a total of 42,330 were built, making it the single most produced military aircraft design in aviation history, as well as one of the most produced piloted aircraft in history along with the American postwar civilian Cessna 172 and the German contemporary Messerschmitt Bf 109.
The Il-2 played a crucial role on the Eastern Front. When factories fell behind on deliveries, Joseph Stalin told the factory managers that the Il-2s were "as essential to the Red Army as air and bread."
Design and development
Origins
thumb|Il-2M at [[MAKS (air show)|MAKS air show]]
The idea for a Soviet armored ground-attack aircraft dates to the early 1930s, when Dmitry Pavlovich Grigorovich designed TSh-1 and TSh-2 armored biplanes. However, Soviet engines at the time lacked the power needed to provide the heavy aircraft with good performance. The Il-2 was designed by Sergey Ilyushin and his team at the Central Design Bureau in 1938. TsKB-55 was a two-seat aircraft with an armoured shell weighing , protecting crew, engine, radiators, and the fuel tank. Standing loaded, the Ilyushin weighed more than , making the armoured shell about 15% of the aircraft's gross weight. Uniquely for a World War II attack aircraft, and similarly to the forward fuselage design of the World War I-era Imperial German Junkers J.I armored, all-metal biplane, the Il-2's armor was designed as a load-bearing part of the Ilyushin's monocoque structure, thus saving considerable weight. The prototype TsKB-55, which first flew on 2 October 1939, The prototypes – TsKB-55 and TskB-57 – were built at Moscow plant #39, at that time the Ilyushin design bureau's base.
The BSh-2 was overweight and underpowered, with the original Mikulin AM-35 engine designed to give its greatest power outputs at high altitude. Because of this, it was redesigned as the TsKB-57, a lighter single-seat design with the more powerful Mikulin AM-38 engine, a development of the AM-35 optimised for low-level operation. The TsKB-57 first flew on 12 October 1940. Deliveries to operational units commenced in May 1941.
The armament of Il-2 was subject to a competition. One of the first 1940 photographs of the Il-2 show it equipped with two MP-6 23 mm autocannons developed by Yakov Taubin (Яков Таубин) at OKB-16. The MP-6 gun weighed and developed an initial muzzle velocity of . It operated on the short recoil principle and had a rate of fire of about 600 rpm. (The development of the MP-6 gun can be traced back to 1937. The initial version was tested in the spring of 1940 on a Messerschmitt Bf 110 bought from Germany, because there was no suitable Soviet aircraft on which to mount it. In the summer of 1940 it was tested on the Pashinin I-21.) Factory trials of the MP-6 gun on the Il-2 were conducted in August 1940. In the early Il-2 prototypes, these guns were fed by 81-round clips. In flight, these clips sometimes became dislodged because of their large surface, which caused them to experience significant aerodynamic pressure. Competitive tests were conducted in the spring of 1941 between the MP-6 gun modified to belt-fed and the newly developed, gas-operated Volkov-Yartsev VYa-23, which had otherwise rather similar characteristics. The VYa-23 was declared the winner at this trial. Subsequently, in May 1941, development of the MP-6 gun was terminated. Taubin was arrested and summarily executed in October that year for plotting to continue production of his failed weapon.
Technical description
The Il-2 is a single-engine, propeller-driven, low-wing monoplane of mixed construction with a crew of two (one in early versions), specially designed for assault operations. Its most notable feature was the inclusion of armor in an airframe load-bearing scheme. Armor plates replaced the frame and paneling throughout the nacelle and middle part of the fuselage, and an armored hull made of riveted homogeneous armor steel AB-1 (AB-2) secured the aircraft's engine, cockpit, water and oil radiators, and fuel tanks.
The extreme survivability of the Il-2 Sturmovik—frequently termed the "Flying Tank"—was made possible by a revolutionary approach to armored protection engineered by VIAM metallurgists Sergey T. Kishkin and Nikolai M. Sklyarov. Rather than simply bolting heavy armor plates onto an existing airframe, Kishkin and Sklyarov designed a load-bearing, highly complex armored shell made of heterogeneous and homogeneous steel plates that functioned simultaneously as the aircraft's forward structural fuselage and fuel tank protection. This armor could deflect high-explosive and armor-piercing rounds from German autocannons without shattering.
Production
In early 1941, the Il-2 was ordered into production at four factories, and was eventually produced in greater numbers than any other military aircraft in aviation history, but by the time Nazi Germany invaded the Soviet Union on 22 June 1941, only State Aviation Factory No. 18 at Voronezh and Factory No. 381 at Leningrad had commenced production, with 249 having been built by the time of the German attack.
Production early in the war was slow because after the German invasion the aircraft factories near Moscow and other major cities in western Russia had to be moved east of the Ural Mountains. Ilyushin and his engineers had time to reconsider production methods, and two months after the move Il-2s were again being produced. The tempo was not to Premier Stalin's liking, however, and he issued the following telegram to Shenkman and Tretyakov: