072-015 KALININ K-7

Airplane constructor Konstantin Kalinin was born in Warsaw in 1887. His greatest success was the K5 passenger plane, which was produced in what was then Soviet Russia in 260 copies. Thanks to this, Kalinin was able to start work on an even larger, but unusual K-7 passenger plane. This design was intended for passenger or transport flights on much longer, transcontinental routes. The originality of the structure was that it was the so-called the flying wing, i.e. the main passenger or transport space, was placed in the wings. Weighing up to 42 tons, the plane had a length of 28 meters and a wingspan of 53 meters, dimensions sky-high for those times. The transport and passenger space in each wing was 6 meters wide, over 10 meters long and almost 2.5 meters high! The plane in the passenger version was to take 120 passengers. Interestingly, Kalinin's office was not the only author of unusual, innovative, unusual structures. In the 1930s, many such machines were created in the world. This was due to the fact that despite the rapid development of aviation during the First World War, the concept of using aviation and creating universal solutions was in its infancy. In the case of the K-7, the cooperation of the Soviet and German military industry is interesting, the installation of BMW engines was considered. Ultimately, however, it was decided to use the native AM-34 design with 750 hp. The design required as many as six such engines. It was absolutely unique that the technicians could access the engines during the flight - it was possible thanks to the thick airfoil and the existence of technical corridors. The cruising speed of the machine was a little 180 km / h, the range was 1600 km. The thick airfoil, with the pilot's cabin, passenger cabin as well as sky-high gondolas housing the entrance hatches, created a very original shape of this plane. Completed in 1931, it made its first flight on August 21 after two years of work. Unfortunately, that same year, after the end of factory tests, the plane crashed. Despite the fact that the work was ordered to continue, it was soon ordered in 1938 to discontinue it due to a change in the priorities of the military and aviation industry in Soviet Russia. Constructor Konstantin Kalinin, who was arrested and executed during the purges, also fell out of favor.