V-12 helicopter: specifications and photos

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The history of helicopter industry in our country has deep roots dating back to the beginning of the last century. Unfortunately, initially in the USSR they did not attach much importance to the development and construction of helicopters, which led to a significant lag behind the United States. Everything changed after the Korean War. Then it turned out that the Americans used helicopters with high efficiency for reconnaissance and sabotage activities. Therefore, the country's leadership gave the order to immediately speed up the development of domestic rotorcraft.

Already by the mid-50s of the last century, the legendary Mi-6, also known as the "Cow", was created. Until now, this helicopter is considered the champion among helicopters in terms of its size and tonnage of the transported cargo. But few people know that the V-12 helicopter (also known as the Mi-12) was also created in the USSR, the carrying capacity of which was supposed to exceed that of the legendary "Cow"!

Brief information about the creation of the machine

After the creation of a truly gigantic Mi-6 helicopter, all leadingengineers and designers of the OKB, headed by M. L. Mil, continued to believe that the possibilities of increasing the size and mass of rotorcraft were far from being exhausted. In addition, the army and the national economy, like air, needed new aircraft. The direction of their takeoff was to be vertical, and the ability to carry cargo - 20 tons or more. By decree from above, the Mil Design Bureau was given "carte blanche" to develop a new helicopter, the creation of which started in 1959.

In 1961, the official terms of reference were issued. It involved the creation of a helicopter capable of lifting loads weighing at least 20 or 25 tons. But even the B-12 helicopter is far from the limit of the demands of the Soviet military and farmers. So, at the same time, the design bureau was working on a version of a machine capable of lifting 40 tons of cargo (V-16 / Mi-16). Note that similar projects were also worked out by the Americans, but they did not go further than sketches. But the work of the Mil Design Bureau finally convinced the Central Committee of the CPSU of the reality of creating such a helicopter.

In 1962, the terms of reference were 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 Design Bureau aircraft. It was assumed that the new vehicle would be used, among other things, for long-distance transportation of various military equipment, including ballistic intercontinental missiles of models 8K67, 8K75 and 8K82. That's what the Mi-12 was created for, a helicopter primarily for military purposes.

First layout options

Practically all domestic and Western luminaries of the helicopter theme believed that a well-studied and well-proven longitudinal scheme would be best suited to create such a helicopter. In order to study its capabilities, the Yak-24 was taken from the army. And in the United States, a Boeing Vertol V-44 was purchased specifically for this. It was on their example that engineers in real conditions investigated the problems of the mutual influence of rotors on each other. The specialists needed to figure out how two motors would behave at once in various flight and operating conditions, how to most profitably use all the advantages of the longitudinal scheme, while avoiding its main disadvantages. A feature of the B-12 was synchronized propellers. Since during the tests a real danger of overlapping of the load-bearing elements was revealed, they had to be placed with minimal overlap. For this, we 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 specifications, as it became unnecessarily large and cumbersome. But even this circumstance was not the main drawback of this design. The main and fatal miscalculation of the engineers was that the air intakes of one group of engines were almost close to the exhaust ports of another. Already during the tests, it was found that the engines in such conditions are prone to the development of surge. And this, in real flight conditions, is fraught with stalling and an instant loss of controllability. Thus, the Mi-12 is a helicopter, during the development of which the designers facedwith many complexities.

In addition, further analysis of the longitudinal scheme led to disappointing conclusions: it does not allow reaching the maximum possible flight ceiling. The speed and weight of the load being lifted were also not up to par. It was also found that if two of the four engines fail, the car falls into free fall. And it was proved that when the flight ceiling is reached and when flying at low temperatures, the power of the motors decreases sharply. That is why the designers unanimously decided to abandon the longitudinal scheme.

Research continues

M. L. Mil himself proposed to come to grips with the consideration of the prospects for other fuselage design schemes. At first, experts suggested using a well-studied single-screw layout. But during subsequent tests, it was found that the scheme with a jet drive of the main rotor would have to be abandoned (due to excessively large dimensions). But the mechanical drive turned out to be a catch. During the tests, it turned out that the design of the gearbox is unnecessarily complex. At first, they tried to cope with the problem by taking two conventional devices from the Mi-6 and placing them on one bearing shaft.

In order to unify, the engineers even used standard Mi-6 blades for the propeller design. In this case, only longer butt tips were used. So they tried to unify the B-12 (helicopter) as much as possible with the rest of the models of equipment in order to reduce the cost of its creation and maintenance. Alas, but in a timely manner to create somethingthis was almost impossible. It was then that a decision was made to start manufacturing a free-standing turbine with a vertically directed shaft. At the same time, it was placed directly under the main gearbox. The gas generator was connected to it through a special gas pipeline.

In this version, the very constructive essence of the turbine was greatly simplified, since it no longer required bevel gears. The problem was that the manufacture of a low-speed gearbox with a diameter of just over four meters is also an extremely difficult task. After all, the latter had a tendency to self-destruction. It is possible, by the way, that the helicopter crash in Syria (12.04.16.) occurred precisely because of the breakdown of the motor gearbox.

Coming to the transverse hull design

Faced with all these specific difficulties, in 1962 the Mil Design Bureau 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, there were some difficult problems in this case too. All this was aggravated by the fact that no one had ever built helicopters of this size in the world. Accordingly, Soviet engineers had to take on the hard work of pioneers. However, scientists in Western countries have repeatedly tried to create rotorcraft according to this scheme. But them time after timebad luck pursued.

Even a number of domestic specialists from TsAGI believed that it was not worth messing with the transverse arrangement of motors at all. This did not frighten Mil himself and his colleagues at all. Competent specialists confidently created the first draft and substantiated its viability before the government commission. After that, the largest helicopter in the world, the Mi-12, received a “start in life.”

Fight against vibration

Again, the team fully took into account the invaluable experience gained by the employees of the Design Bureau of IP Bratukhin. The most difficult thing was the design of sufficiently light and strong consoles for propeller groups. The option with the classic aircraft rectangular wing had to be immediately discarded, since with the required dimensions of the helicopter, this part of the structure turned out to be unnecessarily heavy and cumbersome. It was necessary to create such a console that would be completely free from the problem of spontaneous wandering vibrations, as well as other instabilities. But the most dangerous was the possibility of developing dynamic air resonance, to which propellers on an elastic base were especially susceptible. Because of this, the B-12 helicopter, the characteristics of which we describe, had every chance of falling apart in the air.

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

Helicopter basic characteristics

So, the B-12 helicopter was a four-engine transport vehicle built according to a revolutionary transverse scheme. The propeller groups were borrowed from the Mi-6. They were attached to the long ends of the consoles. Unfortunately, this decision turned out to be not entirely correct, since the Mi-6 propeller, which also did not differ in particularly small sizes, was clearly insufficient. I had to force the engines. More precisely, the Solovyov Design Bureau created a separate version of the D-25F engine, the power of which was immediately increased to 6500 hp. With. I also had to tinker with the wings, which were given a V-section to ensure better aerodynamic performance.

A revolutionary gearbox was installed directly in the center section, which was used to break the transmission shaft. Its uniqueness was not even in the excellent synchronization of the operation of all propellers, but in the excellent operation of the swashplate and the ability to distribute voltage so evenly that flight was allowed even with two failed engines on one side! Fuel was pumped into both wing and separatehanging tanks. The effectiveness of this solution was proven when the largest Mi-12 helicopter in the world made a one-time flight from Moscow to Akhtubinsk.

Fuselage characteristics

The fuselage was manufactured according to the semi-monocoque conceptual scheme. As one of the foreign specialists who was allowed to inspect the helicopter aptly put it, inside it looked like a "giant Gothic cathedral." The entire front part was occupied by the cockpit, which was two-story and provided unprecedented comfort for the pilots at that time. In total, there were six people in the crew. Moreover, four of them were located on the first floor, the rest - on the second. The tail section had a descent power ladder and closing flaps.

This design made it possible (with the help of powerful electric winches) to lift even light tanks on board without much effort. After all, the B-12 helicopter, whose purpose was purely military, was obliged to have such an opportunity. The huge central compartment could accommodate about 200 fully equipped soldiers or 158 wounded (provided that at least ¾ were on stretchers). Under the fuselage there was a tail, made according to the type of an aircraft, equipped with elevators. The rudder was especially important, which makes it possible to significantly improve the accuracy of controlling the rotorcraft in flight. It worked through a synchronizer at the same time as the mechanism that controlled the pitch of the propellers.

In general, the B-12 control scheme has since remained typical for all helicopters with a transversedesign. So, the lifting force was regulated precisely by changing the pitch of the rotors. It also made it possible to control the skew of the helicopter. The automata were responsible for the indicators of longitudinal balancing, by cyclic step (by changing its indicators) it was possible to correct the direction of movement of the helicopter.

Reliability comes first

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

The chassis of the machine from the moment of the first sketches was offered as tricycle. Under the left and right farms, respectively, there were racks. Under the cockpit was the main one. For the first time in the domestic aircraft industry, shock absorbers of a "hybrid" type were used: on hydraulics and pneumatics. In addition, there were auxiliary tail props, which were used when loading heavy equipment. For the newhelicopter, fundamentally new navigation systems have been developed that allow plotting a course in the most adverse weather conditions. In addition, there was an autopilot and a system that automatically corrects the rotational speed of the propellers. So the B-12 helicopter, the design of which we are describing, can be safely ranked among the most advanced examples of technology.

First flights and start of testing

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

It should be noted that the advanced four-engine transverse layout fully justified itself during further tests. In total, the helicopter flew 122 times. Another 77 times hung in the air for a long time. The reliability of the systems and high pilot qualities, which were originally included in the calculations, were fully confirmed. The pilots were delighted with the ease of control of a huge machine. And the military was surprised at the low voracity of the engines.

There is evidence thatflight tests were carried out on two motors, which the machine also successfully passed. But the main triumph of the designers was that, with weight dimensions close to the Mi-6, the helicopter had a carrying capacity increased by 7.2 times! Thus, the B-12 helicopter (manufacturer - OKB Mil) 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 tests were recognized as successful. At the end of the year, a special commission recommended the launch of the helicopter in a series. So why is there no B-12 in the skies of modern Russia? The helicopter, unfortunately, turned out to be unclaimed.

End of story

During the verification process, some design flaws were revealed, due to which its fine-tuning was greatly delayed. In addition, the second copy of the helicopter from 1972 to 1973 stood in the hangar, as suppliers delayed the manufacture of motors. It differed from its counterpart in a much more rigid structure and reinforced controls. Unfortunately, for a number of reasons, in 1974 the program for the creation and development of a unique helicopter was completely curtailed.

Despite its unique characteristics, the B-12 never went into mass production and operation. Firstly, originally created to transport heavy ballistic missiles, it has lost its "target niche". Heavy self-propelled complexes were developed. Secondly, the very concept of basing missiles has also undergone drastic changes due to a sharp increase in their power. Notit was necessary to bring them closer to the territories of a potential enemy.

Thirdly, some of the ICBMs being developed simultaneously with the B-12 and specifically "for it" turned out to be frankly unsuccessful and were never put into service. In other cases, it was much cheaper to send military supplies by land. Fourthly, the plant in Saratov, the only one where it was possible to deploy equipment for the production of helicopters in the shortest possible time, since 1972, “head to head” was loaded with other state orders. There was simply no production capacity left.

Result

Thus, the B-12 is a helicopter that was in many ways ahead of its time, but turned out to be "in the wrong place." If such a machine had been created in the early 60s, then most likely there would have been a job for it. In the 1970s, priorities changed, and the unique design turned out to be unclaimed. But the B-12 helicopter, whose history we described, gave the aviators invaluable experience.