The Yu-7.62 (Ю-7.62) was an aircraft machine gun of Russian origin that boasts an extremely high rate of fire.
At the turn of the 3rd and 4th decades of the 20th century, one of the most exotic projects of aviation small arms, designed by Yuri Fedorovich Yurchenko, was born at the Kovrov machine-gun factory. The machine gun, which had a crank mechanism on the basis of automatic weapons.
Studying the tasks of increasing the rate of fire of weapons, Yurchenko noted that the main problem that significantly affects the rate of fire is that in the classical schemes of operation, the velocity is lost at the extreme points of the shutter stroke. In addition, the increase in the rate of fire with such schemes leads to a significant decrease in the resource of weapons.
Yuriy Yurchenko noticed that in fact this problem was solved already before him, it remains only to realize what was done for the new tasks. Thus, Yurchenko drew attention to the fact that the world's first machine gun Hayram Maximus already carries elements of rapid-fire weapons. Shutter Maxim machine gun crankshaft-type and therefore the speed of its motion varies sinusoidally. With this kind of motion of the shutter, even with an increase in the speed of its movement, its velocity at the beginning and end of the movement is relatively small, and therefore it is possible to rely on smaller inertial force loads on the cartridge, which makes it impossible to destroy or decay it.
Unlike Maxim's machine gun, whose crank parts rotate by an angle of less than 180 degrees, Yurchenko arranged a crank turning as they write on an angle of as much as 350 degrees. This eliminated the impact of moving parts in the extreme rear position. Those. The automation cycle was practically unstressed. At each turn of the crank, a full cycle of automation was performed. The cartridge was accelerated smoothly and the inertial loads on the bullet did not exceed the forces of its pressing into the sleeve and, therefore, there was no decay. Like the machine-gun SHKAS cartridge in the machine gun Yurchenko was not removed from the tape back before being sent to the chamber, but was sent directly forward.
In 1938, Yurchenko presented for testing the version of his machine gun U-7.62 for the cartridge 7.62h54R, in which, in addition to a very simple design, achieved a tremendous rate of fire. The cyclic rate of the Yurchenko machine gun was 5000 rds / min.
True, during the tests at the Noginsk Research Rocket of the Aircraft Armament of the RKKA Air Force, the Yu-7.62 machine gun did not survive such intensive shooting and was returned for revision, it was finalized, tested and put in the plan for 1941 to manufacture the first experimental batch.
But with the onset of the war and the reorientation of the plant to the production of anti-tank rifles, the topic was postponed, and after the war, it no longer rose.
The large-caliber version of the Yurchenko-U-12.7 machine gun was presented for testing in 1939, the cyclic rate was 2000 rds / min, weight 24 kg (for comparison, the serial aircraft machine gun with gas engine UB-12.7 weighed 21 kg at a rate of 1000 rounds per minute). But this option was not adopted because of the transverse dimensions. The profile of the machine gun resembled a guitar (the bar is the barrel, the first bulge is the receiver of cartridges, the second is the crank).
Unfortunately, despite all the advantages of the Yurchenko machine gun, he suffered one drawback, which completely "buried" the development of the design two meters into the ground. The fact is, that at that time, there was still no technology for making barrels that could withstand such a high rate of fire.
Nowadays, the only surviving instance of the U-7.62 machine gun is in the Central Museum of the Armed Forces of the Russian Federation.