Aviation of World War II
Long-range Heavy Bomber
By the middle of the 1930s, two directions for the proposed development of heavy bombers were determined in the Soviet Union. One of them implied a further and, at the same time, a significant increase in carrying capacity. This required aircraft of truly enormous size. And they were built. In 1933, two experimental superheavy aircraft were tested: the six-engine TB-4 (ANT-1b) by A.N. Tupolev and the seven-engine K-7 by K.A. Kalinin. Work was also carried out on the giant bomber TB-6 (ANT-26), capable of delivering 24.6 tons of bombs to the target. However, this direction did not receive further development, since the strengthening of ground and air defense systems made huge slow-moving vehicles very vulnerable. Priority was given to work on aircraft with a carrying capacity close to the TB-Z, but with a significant superiority in flight characteristics. A heavy bomber of this type has been developed since 1934 in the Design Bureau of A.N. Tupolev by the brigade of V.M. Petlyakov.
Like the TB-1 and TB-Z, the new TB-7 (ANT-42) represented a landmark achievement in Soviet aircraft construction. It was the aircraft in which for the first time the new trend in the development of heavy bombers, which became dominant in the next three decades, was to achieve the highest possible speed at high altitudes.
The layout of the four-engine TB-7 was made at the most advanced level for those times. The aircraft had a well-streamlined shape, retractable landing gear, smooth skin, and a relatively thin wing profile. All these qualities provided a significant reduction in aerodynamic drag compared to TB-Z.
The most powerful Soviet M-34FRN engines at that time were installed on the TB-7. But the altitude of these engines, as, indeed, of others, was clearly insufficient. To ensure the required performance, the designers found an original solution: an additional motor was placed in the bomber's fuselage, which, using a special fan, pumped air into the cylinders of the main engines through laid pipelines. Thanks to this unusual solution, the necessary power was obtained at high altitudes. In the future, it was supposed to use a more efficient, individual for each engine injection system, consisting of turbochargers.
Flight tests of the TB-7, which began in December 1936 with the flight of M.M. Gromov, demonstrated the excellent performance of the bomber. The speed of 430 km / h at an altitude of 8600 m made the TB-7 at high altitudes practically inaccessible to serial fighters of those years. For the first time in the history of aviation, a heavy bomber surpassed fighters in speed.
After the completion of state tests in 1938, military experts demanded the urgent organization of the serial production of a new aircraft. However, despite all the advantages and obvious prospects of the TB-7, its mass production has not been established. In the USSR, in the pre-war and war years, the main attention was paid to expanding the production of front-line aircraft, including by reducing the production of heavy bombers. For this reason, during the Great Patriotic War, the Soviet Union lost its primacy in the field of heavy aircraft construction and no longer had, as in the 1930s, a powerful fleet of heavy bomber aircraft. By that time, TB-Zs were clearly outdated, and new TB-7s were produced in small quantities.
TB-7 were built at an aircraft factory in Kazan. The first aircraft were equipped with the already mentioned system of central pressurization of engines. Then they began to install AM-35A high-altitude engines (turbochargers were never put into operation), and for the most part diesel M-30 or M-40, which had the same design. In July 1941, the first combat formation was formed from such aircraft under the command of the famous polar pilot M.V. Vodopyanov, and already in August 1941 this formation raided Berlin. When performing this long-range flight, TB-7s carried three tons of bombs. those. several times more. than twin-engine long-range bombers.
Due to the revealed unreliability of diesel engines, AM-35A began to be installed on TB-7. It was on such an aircraft that the crew of the pilot E.K. Pusep in 1942 delivered to the USA. and then back to Moscow the Soviet diplomatic mission headed by V.M. Molotov.
After the death in 1942 of V.M. Petlyakov. one of the main leaders of the project "42" (TB-7), the TB-7 aircraft was renamed Pe-8.
After the production of AM-35A engines was discontinued, Pe-8 bombers began to be equipped with M-82 air-cooled engines. This version of the Pe-8 was also used after the end of the war, in particular, for research purposes, as well as in polar aviation.
A total of 93 TB-7 (Pe-8) aircraft were built.