Helicopter V-12: specifications and photos

The history of helicopter building in our country has deep roots, dating back to the beginning of the last century. Unfortunately, initially in the USSR special development and construction of helicopters were not given much importance, which caused a significant lag behind the United States. Everything changed after the Korean War. Then it turned out that the Americans with high efficiency used helicopters for reconnaissance and sabotage. Therefore, the country's leadership ordered the immediate acceleration of the development of domestic rotorcraft.

By the middle of the 50s of the last century the legendary Mi-6 was created, it is also the "Cow". Until now, this helicopter is considered a record among helicopters in terms of its size and tonnage of the cargo being transported. But very few people know that in the USSR was also created a helicopter V-12 (also known as Mi-12), the carrying capacity of which should exceed that for the legendary "Cow"!

Brief information about the creation of the machine

After the creation of the truly giant Mi-6 helicopter, all the leading engineers and designers of the Design Bureau, headed by ML Mil, continued to believe that the possibilities for increasing the size and weight of rotorcraft were far from exhausted. In addition, the army and the national economy, like air, needed new aircraft. The direction of their take-off should have been vertical, and the ability to transport cargo - 20 tons or more. By decree from the top of the OKB Mil was given "carte blanche" for the development of a new helicopter, the creation of which started in 1959.

In 1961, the official technical task was published. It presupposed the creation of a helicopter capable of lifting loads of at least 20 or 25 tons. But even a V-12 helicopter is far from the limit of the demands of the Soviet military and agrarians. So, at the same time, the OKB worked out a variant of a machine capable of lifting 40 tons of cargo (V-16 / Mi-16). It should be noted that similar projects were also worked out by the Americans, but they did not go further than the sketches. But the work of the MKB OKB finally convinced the Central Committee of the CPSU in the reality of creating such a helicopter.

In 1962, the technical assignment was once again finalized. Engineers were instructed to focus on the creation of a helicopter with a cargo cabin, similar in characteristics to those of Antonov OKB planes. It was assumed that the new machine would be used, among other things, for transporting various combat equipment for long distances, including ballistic intercontinental missiles of the 8K67, 8K75 and 8K82 models. That's what the Mi-12 was for, a helicopter of predominantly military purpose.

First Layout Options

Almost all domestic and western luminaries of helicopter subjects believed that a well-studied and well-proven longitudinal scheme would best suit the creation of such a helicopter. In order to study its capabilities, the Yak-24 was taken from the army. And in the USA specially for this purpose the Boeing-Vertol V-44 was purchased. It was on their example that engineers in real conditions investigated the problems of mutual influence of the rotors. Specialists were required to find out how the two motors behave in different conditions of flight and operation, how all advantages of the longitudinal scheme can be used most advantageously, while avoiding its main shortcomings. Feature of the V-12 steel synchronized screws. Since during the tests the real danger of overlapping of bearing elements was revealed, they had to be placed with minimal overlap. For this, even had to sacrifice some of the aerodynamic qualities of the new machine.

As a result, the fuselage completely ceased to meet the requirements of the technical assignment, as it became unnecessarily large and cumbersome. But not even this circumstance was the main drawback of this design. The main and fatal mistake engineers made was that the air intakes of one group of engines were almost close to the exhaust openings of the other. Already on tests it was found out that engines in such conditions are inclined to development of surging. And this in real flight conditions is fraught with stalling and instant loss of controllability. Thus, the Mi-12 is a helicopter, in the development of which designers faced many difficulties.

In addition, further analysis of the longitudinal scheme led to disappointing conclusions: it does not allow to achieve the maximum possible flight ceiling. The speed and weight of the lifted cargo also did not turn out to be at a high altitude. It was also found out that if two of the four engines fail, the machine falls into a free fall. And it was proved that when the flying ceiling is reached and when flying in conditions of low temperatures, the power of the engines is sharply reduced. This is why the designers unanimously decided to abandon the longitudinal scheme.

Continuation of research

ML Mill himself suggested that we should start looking closely at the prospects for other schemes for the construction of the fuselage. First, experts suggested using a well-studied single-screw layout. But in the subsequent tests it was found out that the circuit with the reactive drive of the main rotor would have to be abandoned (due to excessively large dimensions). But the mechanical drive was a trick. In the process of testing, it turned out that the design of the reducer is too complicated. First, they tried to cope with the problem by taking two conventional devices from the Mi-6 and placing them on a single carrier shaft.

For the purposes of unification, engineers even used standard Mi-6 blades for the design of the screw. At the same time, only the feather tips were used. So the B-12 (helicopter) tried to unify as much as possible with other samples of equipment, in order to reduce the cost of its creation and maintenance. Alas, but in a timely manner to create something similar was almost impossible. It was then that it was decided to start manufacturing a free-standing turbine with a vertically directed shaft. It was placed directly under the main reducer. The gas generator was connected to it by means of a special gas pipeline.

In this case, the very essence of the turbine was simplified considerably, since it no longer required bevel gears. The problem was that the manufacture of a slow-speed reducer with a diameter of just over four meters is also a very difficult task. After all, the latter had a propensity for self-destruction. Perhaps, by the way, that the helicopter crash in Syria (April 12, 16.) Occurred precisely because of the breakdown of the motor reducer.

Arrival to the transverse housing design

Faced with all these specific difficulties, in 1962, the specialists of the MIL OKB finally decided to abandon the idea of "single-engine experiments." They again returned to the scheme with two engines. True, this time it was decided to work out a variant with a transverse arrangement of motors. This is exactly what the helicopter "12" became, the photo of which is in our article.

Of course, this was not without difficult problems. All this was aggravated by the fact that no one had ever built helicopters of this size in the world. Accordingly, the Soviet engineers had to take on the hard work of the pioneers. However, scientists in Western countries have repeatedly tried to create rotorcraft in this particular way. But they were repeatedly failures.

Even a number of domestic specialists from TsAGI believed that it was not worthwhile to bother with the transverse arrangement of motors. The very Mile and his colleagues did not at all frighten it. Competent specialists confidently created the first project and substantiated its viability before the government commission. After that, the biggest helicopter in the world, the Mi-12, received a "trip to life."

Combating Vibration

Again, the collective fully took into account the invaluable experience accumulated by the employees of the OKB Bratukhin. The most difficult was the design of fairly light and sturdy consoles of propeller-driven groups. The version with the classic airplane rectangular wing immediately had to be discarded, since with the required dimensions of the helicopter this part of the design turned out to be unnecessarily heavy and cumbersome. It was required to create such a console that would be completely free from the problem of spontaneous arising vagrant vibrations, as well as other instabilities. But the most dangerous was the possibility of developing a dynamic air resonance, to which the screws on the elastic base were particularly exposed. Because of this, the B-12 helicopter, the characteristics of which we describe, had every chance to fall apart in the air.

When the work with the first prototype was completed, the initial tests were decided to be carried out directly in the shop, so that any gross defects, if any, should be corrected immediately, without wasting time. To achieve the flight effect, special dynamic cords and vibrators were used, simulating resonant sensations that arise when the screws rotate. It should be noted that for this invention alone, all employees could be bravely rewarded, since nothing like this has been done before in the world aircraft industry. Soon the test results confirmed the correctness of all calculations. And by 1967 the helicopter was recognized as fully prepared for real flight tests.

Basic characteristics of the helicopter

So, the V-12 helicopter was a four-motor vehicle built on a revolutionary cross-sectional scheme. The propeller-driven groups were borrowed from the Mi-6. They were attached to the long ends of the consoles. Unfortunately, such a solution turned out to be not entirely correct, since the Mi-6 screw, which was also not particularly small, was clearly inadequate. I had to boost engines. More precisely, OKB Soloviev created a separate version of the engine D-25F, the power of which was increased immediately to 6500 liters. from. I had to tinker with the wings, which, in order to ensure the best aerodynamic performance, were given a V-shaped cross-section.

Directly in the center wing was installed a reducer of revolutionary design, used for the fracture of the transmission shaft. Its uniqueness was not even in the excellent synchronization of the work of all the screws, but in the excellent performance of the skew machine and the ability to distribute the voltage evenly enough that a flight was permitted even with two failed engines on the one hand! The fuel was pumped in both winged and separate hinged tanks. The effectiveness of this decision was proved when the world's largest helicopter Mi-12 made a one-time flight from Moscow to Akhtubinsk.

Characteristics of the fuselage

The fuselage was manufactured according to the conceptual scheme of semi-monocoque. As one foreign specialist aptly put it, who was allowed to inspect the helicopter, he looked like a "giant gothic cathedral" inside. The whole front part was occupied by the crew cabin, which was two-storied and provided unprecedented comfort for the pilots at that time. In all, the crew had six men. And four of them were located on the first floor, the rest - on the second. The tail part had a descending power ladder and closing flaps.

This design allowed (with the help of powerful electric winch) to lift on board even light tanks, without exerting much effort. After all, the V-12 helicopter, whose mission was purely military, was obliged to have such an opportunity. In the huge central compartment could accommodate about 200 soldiers in full computation or 158 wounded (provided that not less than ¾ were on a stretcher). Under the fuselage was a tail unit, made as an aircraft, equipped with elevator controls. Particularly important was the rudder, which makes it possible to significantly improve the accuracy of controlling the rotorcraft in flight. It worked through the synchronizer simultaneously with the mechanism controlling the pitch of the screws.

In general, the control scheme of the V-12 has since been retained as a model for all helicopters with a transverse design. So, the lifting force was regulated precisely by changing the pitch of the rotors. Also it allowed to control the skew of the helicopter. The machines were responsible for the indicators of longitudinal balancing, a cyclic step (a change in its performance) could be corrected the direction of the helicopter.

Reliability - above all!

The entire control and wiring system of the helicopter was designed taking into account possible deformations and high friction indexes. That is, the emphasis was immediately on resistance to wear. It was designed in two cascades. So, there were main and additional hydraulic amplifiers, as well as many automatic synchronizers, greatly simplifying the management of the helicopter with four engines. The main hydraulic system was located in the same compartment as the main reducer. The most important amplifiers, in addition, were fed from backup systems located in the right and left nacelles. In total, there were three hydraulic systems. Each of them was not only completely autonomous, but also duplicated separately. In a word, the world's largest helicopter, the Mi-12, was also the most reliable.

The chassis of the machine from the time of the first sketches was proposed to be tri-axial. Under the left and right farms, respectively, there were their stands. Under the crew cabin was the main one. For the first time in the domestic aircraft construction, shock absorbers of the "hybrid" type were used: in hydraulics and pneumatics. In addition, there were auxiliary tail supports, which were involved in the loading of heavy equipment. For the new helicopter, principally new navigation systems have been developed, which allow to lay the course in the most unfavorable weather conditions. In addition, there was an autopilot and a system that automatically corrects the rotational speed of the screws. So the B-12 helicopter, the design of which we described, can be safely ranked among the most advanced examples of technology.

The first flights and the beginning of tests

At the end of June 1967, the car first flew into the air. It should be noted that already in the first flight it was found out that there is another, special system of oscillations, when the vibration was transmitted directly to the controls. This was due to the miscalculations of the designers who, through direct kinetic coupling, connected the control and drives of the engines. Because of this, only the giant that had just risen into the air was forced to make an emergency landing. All the shortcomings were quickly analyzed and eliminated by increasing the overall rigidity of the structure. So, the V-12 helicopter, whose advantage consisted of a colossal carrying capacity, was completely rehabilitated.

It should be noted that the advanced four-motor transverse scheme fully justified itself in the course of further tests. In total, the helicopter flew 122 times. Another 77 times for a long time hanging in the air. The reliability of the systems and the high pilot quality, originally laid out in the calculations, were fully confirmed. The pilots were delighted with the simplicity of running a huge machine. And the military was surprised at the low gluttony of the engines.

There are reports that tests were carried out on two engines, which the car also successfully passed. But the main triumph of the designers was that with weight dimensions close to the Mi-6, the helicopter possessed the carrying capacity, increased by 7.2 times! Thus, the V-12 helicopter (the manufacturer - MIL OKB) had every chance of a successful "career" in the USSR Air Force. In 1970, he flew from Moscow to Akhtubinsk and back, after which the state trials were recognized as successful. At the end of the year, a special commission recommended the launching of a helicopter in a series. So why is there no B-12 in the sky of modern Russia? Unfortunately, the helicopter was unclaimed.

End of story

In the process of verification, some design flaws were revealed, which made its debugging time-consuming. In addition, the second copy of the helicopter from 1972 to 1973 stood in the hangar, as the suppliers were delayed with the manufacture of motors. He differed from his colleague by a much more rigid design and strengthened controls. Unfortunately, for a number of reasons, in 1974 the program for creating and finalizing a unique helicopter was completely canceled.

Despite its unique characteristics, the V-12 helicopter never entered mass production and operation. Firstly, initially created to transport heavy ballistic missiles, it lost its "target niche." Heavy self-propelled complexes were developed. Secondly, the very concept of the basing of missiles due to a sharp increase in their capacity has also undergone drastic changes. It was not necessary to bring them closer to the territories of the potential enemy.

Thirdly, some of the ICBMs developed simultaneously with the B-12 and specially "under it" were frankly unsuccessful and were not accepted for service. In other cases, it was much cheaper to send military cargoes on land. Fourthly, the plant in Saratov, the only one where it was possible in the shortest time to deploy a rig for the production of helicopters, since 1972 "on the head" has been loaded with other government orders. Production capacities there simply did not remain.

The result

Thus, the B-12 - a helicopter, largely ahead of its time, but was "in the wrong place." If such a machine were created in the early 60's, then most likely, the work would be for her exactly. In the 1970s, priorities changed, and the unique design was unclaimed. But the V-12 helicopter, whose history we described, gave the pilots invaluable experience.