Vertical hinge of the Mi 8 helicopter. Russian Aviation. Air command posts

- a medium multi-purpose helicopter that is used for passenger and cargo transportation. It performs a wide range of tasks in any region of the planet.

The development of the V-8 (Mi-8) helicopter began at the Design Bureau named after. M.L. Mil (now JSC Moscow Helicopter Plant named after M.L. Mil, part of the Russian Helicopters holding company) in May 1960 to replace the Mi-4 multi-purpose piston helicopter, which had proven itself in operation. The Mi-8 was created as a deep modernization of the Mi-4 helicopter with a gas turbine engine. The helicopter was developed simultaneously in two versions: the passenger Mi-8P and the transport Mi-8T.
The first prototype of the new helicopter (with one engine and a four-blade rotor) took off in July 1961, the second (with two engines and a five-blade rotor) - in September 1962, the first flight of the prototype helicopter took place in 1962.

Serial production of the Mi-8 began in 1965 at OJSC Kazan Helicopter Plant and OJSC Ulan-Ude Helicopter Plant.

Seven world records were set on Mi-8 helicopters in 1964-1969 (mostly by female helicopter pilots).

The Mi-8 exceeds the Mi-4 helicopter in maximum load capacity by 2.5 times and in speed by 1.4 times. The transmission of the Mi-8 helicopter is similar to the Mi-4 helicopter.

The helicopter is made according to a single-rotor design with a tail rotor, two gas turbine engines and a tricycle landing gear.
The main rotor blades are all-metal. They consist of a hollow spar pressed from an aluminum alloy. All main rotor blades are equipped with a pneumatic spar damage alarm. The control system uses powerful hydraulic boosters. Mi-8 is equipped with an anti-icing system that operates in both automatic and manual modes. The helicopter's external suspension system allows it to transport cargo weighing up to 3000 kilograms.
If one of the engines fails in flight, the other engine automatically switches to increased power, while horizontal flight is performed without reducing altitude. The Mi-8 is equipped with an autopilot that provides stabilization of roll, pitch and yaw, as well as constant flight altitude. Navigation and flight instruments and radio equipment that the helicopter is equipped with allow it to fly at any time of the day and in difficult weather conditions.

The helicopter is mainly used in transport and passenger versions. In the passenger version, the helicopter (Mi-8P) is equipped to transport 28 passengers. By special order, in Kazan, a version with a luxury cabin can be manufactured, designed for seven passengers. Such orders were carried out for Boris Yeltsin, Nursultan Nazarbayev, Mikhail Gorbachev.

Military option Mi-8T has pylons for hanging weapons (unguided missiles, bombs). The next military modification of the Mi-8TV has reinforced pylons for hanging a large number of weapons, as well as a machine gun mount in the bow of the cabin.
Mi-8MT— modification of the helicopter, which was the logical conclusion of the transition from a transport to a transport-combat helicopter. More modern TVZ-117 MT engines with an additional AI-9V gas turbine unit and a dust protection device at the entrance to the air intakes are installed. To combat surface-to-air missiles, there are systems for dispersing hot engine gases, shooting false thermal targets and generating pulsed IR signals. In 1979-1988, the Mi-8MT helicopter took part in the military conflict in Afghanistan.

The Mi-8 can be used for a variety of tasks: for fire support, suppression of fire points, delivery of troops, transportation of ammunition, weapons, cargo, food, medicine, evacuation of the wounded and dead.
The helicopter is unpretentious and trouble-free. The Mi-8 abroad, and here too, is called a “workhorse”, a “soldier’s machine”.
Mi-8 helicopters are the most common transport helicopters in the world.
In the history of the world helicopter industry, in terms of the total number of machines produced - over 12 thousand (about 8,000 in Kazan and over 4,000 in Ulan-Ude) - the Mi-8 helicopter has no analogues among devices of its class.
In terms of the number of modifications, the Mi-8 is a world record holder. There are more than a hundred of them. Modifications were created at the Moscow Helicopter Plant named after. M. L. Mil, at the Kazan and Ulan-Ude factories, repair enterprises, directly in military units and Aeroflot detachments, as well as abroad during operation.

Among the measures contributing to this, the comprehensive development of transport, including civil aviation, was named. At the same time, defense spending was reduced, and the freed-up funds were planned to be used again to improve the people's well-being. A “thaw” began within the country, and detente began in the world as a whole.

The main Soviet army helicopter of the 50s was the piston Mi-4. It was to be replaced by the gas turbine Mi-8
Photo: Moscow Helicopter Plant named after. M.L. mile

During this period, the creation of the first generation of aircraft with jet and turboprop engines, as well as the Mi-6 heavy helicopter, was successfully completed. Its creator M.L. Mil also proposed a project for a new medium helicopter B-8.

It was originally created as a version of the Mi-6 reduced to the size of the Mi-4 with two gas turbine engines. The project was supported by the Central Committee of the CPSU, but the State Planning Committee could not understand that the increase in the cost of development, production and operation of a helicopter compared to an aircraft of the same carrying capacity by 1.5...2 times is an objective reality, and not mismanagement on the ground, and this In the department, the helicopter industry turned out to have staunch opponents. Aeroflot became interested in the new helicopter, and on February 20, 1958, a resolution of the Council of Ministers determined an order for the B-8. But to please the “guys from Gosplan,” the OKB agreed to make it not as a new machine, but as a modification of the Mi-4 under one AI-24V gas turbine engine, a modification of the “aircraft” engine designed by Ivchenko. M.L. himself continued to play the main role in the engineering development of the machine. Mil, but for the B-8 other responsible managers were appointed in the OKB structure: Chief Designer V.A. Kuznetsov and presenter - G.V. Remezov.

Already during the pre-design study, in agreement with the Customer (and since 1959, there were already two departments for the B-8 - Aeroflot and the Air Force), it was decided to increase the size of the helicopter while maintaining a payload capacity of 2 tons, as well as to simultaneously design a number of modifications of the B-8. A passenger version, civil and military transport, army armed and naval anti-submarine helicopters were created. Today we will focus on options for army aviation.

The V-8 moved further and further from its “prototype” Mi-4 both in its layout and in “little details”: it used “blown” transparent glazing panels, adhesive-welded joints, and large-sized stampings. In the control system, the hydraulic boosters were interlocked with other hydraulic units into a compact “hydraulic combine” and hung directly on the main gearbox. Hydraulic dampers were installed in the vertical hinges of the main rotor instead of friction dampers, and trimmers were installed on the blades. Instead of two front supports, they made one, etc.

That same year, production of five prototype B-8s began. The OKB's own production base, exhausted by relocations, was still weak (the Milevians had been at plant No. 329 for more than five years, but had not yet had time to acquire everything they needed). The main units were made by Plant No. 23, where OKB-329 had a representative office and the Mi-6 was mass-produced. The first prototype was assembled by Plant 329. It was delivered in a passenger version with an 18-seat luxury cabin and in a modest but beautiful coloring, however, without a civil registration number and the “Aeroflot” inscription. The first flight on it was made by a factory crew under the command of B.V. Zemskova June 24, 1961.

The installation of two engines instead of one opened the way to improved flight performance and increased reliability of the Mi-8
Photo: O. Yakubovsky

The G8 not only quickly and successfully passed the factory testing stage, but also immediately caught the fancy of the top party leadership. Mil attached paramount importance to demonstrations of the vehicle, and after a couple of weeks the B-8 took part in the Tushino air parade, and then was exhibited with great success at VDNKh, where it was immediately noticed by the foreign press.

At the end of 1961, the V-8 was transferred to State tests, but Mil already knew that the single-engine vehicle would not go further.

The first decision is the most correct one

Taking advantage of Khrushchev's interest in helicopters, Mil convinced both customers and the State Planning Committee of the need for two engines. This was no longer a modification of the Mi-4, but a completely new product, expensive but effective. Khrushchev, having visited the USA, saw “their” government helicopters and was inspired by the idea of such a machine, and one engine did not provide sufficient reliability - and on May 30, 1960, a decree was issued on the B-8A helicopter with two light and economical gas turbine engines of 1250 hp each. . development of the Leningrad KB-117 S.P. Izotov. At first, a competitive development was planned, but, oddly enough, there were no more people willing to take on this order. The same team also made the new gearbox. During the design, while maintaining the specified weight of 300 kg and length of 3 m, it was possible to increase the power to 1500 hp. on takeoff. This guaranteed landing at a remote site at any flight weight on one engine.

The B-8A helicopter with two gas turbine engines entered testing in a passenger version. The first hover on it was carried out on August 2, 1962. In March 1963, the vehicle was transferred to State tests, in which both civilian pilots and military personnel from the Air Force Research Institute took part.

Serial army transport helicopter Mi-8T of the first series without weapons
Photo: O. Yakubovsky

Despite the overall success of the tests, various modifications, sometimes quite serious, were constantly made to the helicopter design.

Firstly, a “quiet” five-blade main rotor with a reduced vibration level appeared. We resolved the issue of synchronizing the rotation of motor shafts and stabilizing the NV frequency within specified limits. An emergency mode was introduced to briefly increase the power of one engine when the second one failed. The AP-34 autopilot was unified with the Mi-4 and Mi-6. The vibration of the helicopter at the moment of takeoff and touch (“ground resonance”) was eliminated by installing two-chamber liquid-gas landing gear shock struts instead of primitive single-chamber ones. The wheels of the main supports are enclosed in fairings. True, the “bast shoes” were not in demand in the series. Soon the B-8A was transferred for endurance testing, and then again for flight testing, but in 1966 the car died in a crash due to the destruction of the tail rotor hub.

In the summer of 1963, the third vehicle, the V-8AT, entered testing. This was the first helicopter for the Air Force. Behind the large rectangular windows of the passenger version there was a cabin for 20...24 paratroopers, and in the bow there was a nest for an A-12.7 machine gun, which was empty for now. “Car” doors were replaced with sliding ones, which was later adopted for the civilian version. The rest of the car was similar to the B-8A. After short factory tests, the V-8AT passed into the hands of the military.

The experimental B-8AP No. 4 was supplied with a government cabin, which contained chairs for the “main passenger” and assistant assistant, separated by a mahogany table from the “guest” chair, as well as armchairs and a side sofa for accompanying persons. The car had new communication and household equipment. It was on the V-8AP that stage “B” of the State Tests began in September: confirmation of the declared characteristics by the Customer’s testers. A month later, the same process began on the third machine. In the spring of 1965, the V-8AP was once again radically redesigned. A regular passenger cabin with 28 seats was installed on it. This arrangement later became the basis for the serial version for the MGA.

The fifth experimental helicopter became the standard for the series. In 1965, a positive conclusion based on the results of State tests was issued for the passenger, and then for the transport and landing versions.

The ubiquitous Mi-8

Initially, it was planned to produce the new Mi-8 helicopter at plant No. 23 in Fili, where the Mi-6 was mass-produced. But this enterprise was given over to the experimental base of the Chelomey missile design bureau and is still working “for space”, and the production of the Mi-8 was transferred to Tataria, far from Moscow, to plant No. 387 in Kazan. He had already built Mi-1 and Mi-4 helicopters, and in the early 60s he began to receive documentation in versions for Aeroflot (Mi-8P) and the Air Force (Mi-8T). In 1965, when the B-8 was still being tested, the first production vehicles were accepted by the Customer.

The development of the Mi-8 made it possible for the plant to move from producing aircraft for auxiliary purposes to products that were at the forefront of government plans. The plant has grown both in area and in quality. On its basis, a representative office of the Mil Design Bureau was formed, then it received the status of a branch, and now an independent design bureau is successfully operating there, which is involved in the process of improving the Mi-8 and Mi-17.

In the early 70s, an aircraft plant in Ulan-Ude, Buryatia, joined the production of the Mi-8. Before that, this company built Ka-25 helicopters, but the order for them was small. “The plan was made” by a large series of An-24, but the management wanted to “narrow” the scope of activity and “knocked out” an order for the Mi-8 helicopter, but still could not get away from the aircraft theme. In parallel with the Mi-8, the company first built the MiG-27, and then the famous “rook” - the Su-25 attack aircraft.

The serial production of the “eight” quickly gained momentum and became an indicator of which of the two customers, represented by the Ministries of Civil Aviation and Defense, has the “right of first night” in relation to the order for helicopters, which until recently had not aroused any particular interest among anyone. MGA received its “rotor-wing airliners”, but later most of them were delivered in the Mi-8T variant and mainly to the Air Force. Production continued for more than 30 years and stopped in Kazan in 1996, but soon the market still demanded it to be restored. About 4,000 Mi-8s were made there.

In Ulan-Ud, the last Mi-8T was delivered in 1994; this plant gave the country about 3,700 Mi-8s with the power plant of the first version. Interestingly, the helicopter turned out to be in such demand that even the Yeltsin-Gaidar bacchanalia of the early 90s could not completely stop its production.

The undoubted advantage of the Mi-8 over similar American and European vehicles is its large payload capacity and convenient loading ramp.
Photo: archive of D. Proskurnin

The Eight was larger and more complex than the Mi-4, nevertheless its production in the shortest possible time became widespread. This was largely due to a well-thought-out design that combined technologically justified innovations and time-tested traditional solutions. Already the first series included 40 cars. Almost immediately with the start of production, modifications began to be made based on the results of production and operation. Here are just a few.

The requirements for the accuracy of cargo placement in the cabin turned out to be somewhat excessive and difficult to implement. Therefore, already on the 17th car of the 1st series (“short” serial number 1701), the permissible range of the position of the center of mass of the cargo was somewhat expanded, which was externally reflected in the markings of the cargo compartment.

On the 22nd helicopter of the 1st series Mi-8T (machine 2201), main external tanks of increased capacity were introduced. The same tanks on civilian Mi-8Ps were introduced a little later - from vehicle No. 1015.

By the end of the 60s, more reliable TV2-117A engines with an increased service life were introduced. Around the same time, instead of the old RP-7422 icing alarms, new radioisotope RIO-3 ones were installed, which ensured the simultaneous automatic activation of the POS of both engines and the helicopter. In this regard, the POS switching system for APS-2 engines was removed. True, there were still complaints about the new sensors, in particular, they did not work well at near-zero temperatures, where the danger of icing was greatest. The Mi-8 POS has been refined for a long time by the OKB, LII MAP, ERAT Research Institute and other organizations, but even now it is “more likely solved than not.”

In the 80s a Doppler speed and drift meter appeared on the Mi-8T; unlike the previously installed DIV device, it worked in any mode. DISS-15 was installed in a “bath” under the tail boom. Then newer models of Doppler equipment appeared, both domestic and imported.

Mi-8TV helicopter with a nose mounted A-12.7 machine gun of the Afanasyev system
Photo: A. Artyukha

Not all useful innovations were brought to series, for which there were both objective and “incomprehensible” reasons. An example of this was the improvement of the main rotor. We tried dozens of options, some were very successful, but none of them reached the consumer. The struggle for the life of the tail rotor did not end in anything. After a difficult search for its optimal design, a semi-rigid five-bladed propeller was created, which was recommended for production, but production never mastered it. Meanwhile, the total service life of the machine was increased to 20,000 flight hours, and reducing the range of units replaced during this period according to its own resource is a commercially important task.

They tried to “smooth out” the aerodynamics of the helicopter - the external tanks were removed into the fuselage, fairings were installed on the HB hub and engine exhaust pipes, new cargo flaps were installed, and the sealing of the fuselage was improved. But it was not possible to “cross a horse and a tremulous doe” - the performance characteristics of the vehicles did not improve dramatically, and this set of improvements was not implemented on the Mi-8T.

At one time, a program was also proposed for the gradual modernization of the TV2-117 engine while maintaining a lower cost compared to the new TV3-117. However, this new gas turbine engine “eclipsed” it with its high characteristics.

For quite a long time, the Mi-8 suited the military in the “naked” form in which it was born. Now it’s simply strange to see the army “eight” without the usual pylons for weapons. Foreign magazines of those years were full of photographs of “Iroquois”, “Sinites”, “Choctaws” and so on and so forth, hung with machine-gun turrets and missiles. Finally, our Customer began to move, and the OKB was paid for the work of installing weapons on the Mi-8. True, they approached the choice of weapons in a strange way.

The Mi-8TV attack helicopter provided for the use of an A-12.7 machine gun in the bow mobile unit, unguided aircraft missiles (4 blocks of 16 S-5 shells each) and 4 bombs of caliber from 50 to 500 kg. But, having calculated the mass of weapons, the designers realized that they had to get rid of one thing, and decided to sacrifice the machine gun. As a result, the Mi-8 could become similar to the fighter-bomber of those years, but the Mi-8 is a truck, and it is still difficult for it to dive dashingly at a target with bombs and missiles. It would have been much more useful to leave a machine gun on board, and it wouldn’t have hurt to think about means of increasing survivability even then.

The Mi-8TV was officially put into service only in 1969, when it had been serving in the army for four years. Finally, the state deservedly noted the work of the OKB. Prominent employees of the “company” A. Braverman, S. Kolupaev, V. Kuznetsov, G. Remezov and E. Yablonsky became laureates of the USSR State Prize for 1968 for the creation of the Mi-8. And the armed Mi-8 itself went into production for the Air Force, but it retained the same name and was delivered as the Mi-8T. During serial production, the suspension was simplified without reducing its capabilities and flight characteristics. In particular, the DB mounting truss pipes of a streamlined oval cross-section used on the experimental vehicle were replaced with simple and cheap round ones.

The transport-combat Mi-8TV could carry the Phalanx or Malyutka ATGM, blocks of S-5 unguided missiles or bombs, and an A-12.7 machine gun was installed in the bow
Photo: Moscow Helicopter Plant named after. M.L. mile

The shortcomings of the first weapon version were obvious, and in 1974 the second version of the Mi-8TV was released. The NUV-1-2M machine gun mount with the Afanasyev heavy machine gun was installed in the lower segment of the cockpit glazing. This firing point, together with the K-10 sight, has already been well developed in production for the Mi-4, Mi-6 and Mi-24A helicopters. All other weapons were also significantly strengthened.

Instead of four beam holders of the 3rd group, that is, allowing the suspension of ammunition weighing up to 500 kg, they made six. They were also equipped with UB-32 blocks, with which the helicopter’s missile salvo reached an impressive size - 192 S-5 projectiles. And above the four external databases they installed beam launchers for Phalanx anti-tank guided missiles. But tests showed that such a “flying dreadnought” loses its flight qualities, and few production Mi-8TVs were built. This modification was exported under the designation Mi-8TB. They differed from their Soviet counterparts in the installation of old 9M14M “Malyutka” ATGMs (for the GDR) or their complete absence (for Nicaragua).

The Moscow Helicopter Plant made several special modifications of the basic Mi-8T helicopter with weapons, but they remained experimental. Perhaps the most successful of them was the development of the Mi-8AV (Mi8VSM) aerial minelayer for ground forces. The VMR-1 minelayer, developed for the Mi-4, was installed in its fuselage; the rest of the weapons remained the same as the Mi-8TV model of the 68th year. At first, the Mi-8AV could lay 64 mines, then their number was increased to 200. To lay small-sized non-retrievable anti-personnel mines, the Mi-8AD version was made. A small number of minzags were supplied to the USSR Air Force units.

The helicopter group of the USSR Air Force was growing. Separate transport and combat regiments were formed, armed with transport Mi-8s and combat Mi-24s. It was believed that in case of war they should have increased mobility, in other words, work in isolation from stationary bases. In order to prevent a drop in the combat readiness of units under these conditions, the Mi-8TECH-24 flying technical and operational unit was designed. On board it was installed the most necessary plumbing, electrical, testing and other equipment, most often used in the daily operation of helicopters and for repairing damaged machines. A prototype of this modification was submitted for testing in 1977 and subsequently the TECH helicopter was built in a small series.

In the same 1977, another modification of the helicopter appeared - the Mi-8TZ tanker and fuel transporter. It joined the fleet of Mi-4 and Mi-6 for similar purposes in both the Air Force and Aeroflot.

Greater success accompanied the consistent improvement of previously built machines. The possibility of installing additional weapons gradually became available on conventional combat “armed transport vehicles.” First of all, a bow rifle mount was mounted on some of the helicopters and they provided suspension for B-8V blocks intended for the new S-8 80 mm caliber NARs, much more powerful than the 57 mm S-5. Later, armor was installed on some of the helicopters - flat sheets behind the glass of the pilots' doors and faceted ones on the outside along the sides of their cabin. But for some reason they did not protect the crew from below.

Much work on bringing the Mi-8T up to wartime requirements was carried out during the provision of “international assistance” to Afghanistan. Through the efforts of combat units and industry, additional machine guns or even an AGS-17 mounted grenade launcher in doors and hatches, and PKT machine guns on the weapons farm, began to be installed on combat vehicles. On the databases themselves they began to “hang” UPK23-250 cannon nacelles, disposable bomb clusters and containers with small mines and KMG-U bombs. They were replaced with a more powerful PKT tank machine gun and a standard A-12.7 in the bow mount. We installed an automatic jamming system for portable heat-seeking anti-aircraft missile systems. Methods for reducing thermal radiation from engines were also being worked on for the Mi-8T - screen-exhaust devices, or EDUs. But they went into production only on the Mi-8MT and in a greatly modified form.

Two technicians can stand on the inside of the open hood of the engine compartment of the Mi-8, performing work on the engine
Photo: N. Okolelova

The conditions in Afghanistan also prompted action to improve the performance characteristics of the vehicle. Engine starting in hot weather and at high altitude has been improved. What is typical is that there was no need to invent anything - since 1973, an export version of the helicopter for Syria, the Mi-8TS (for dry climates), was produced, which provided for such modes.

The Mi-8 helicopter was intended for operations over land, but for a country with such a long coastline, the need to use its main helicopter over the sea could not but arise. The first naval versions did not differ much from the base model. They were intended to operate only from shore bases in the coastal zone. Their tasks have also changed little - delivery of goods and people to remote “points”, medical service, aerial surveillance - depending on the requirements of the operator. Subsequently, a special marine helicopter, the Mi-14, was designed on the basis of the Mi-8, but here we will not dwell on this machine, which deserves a separate publication.

One of the first specialized naval variants of the Mi-8 appeared not to solve internal problems, but to meet the requirements of the international situation. After the Arab-Israeli War of 1973, the waters of the Mediterranean and Red Seas, as well as the strategic Suez Canal, ceased to be safe - both sides of the conflict thoroughly littered them with mines, including bottom mines with remote fuses. In order to clear the most important routes for the entire world and our own shipping, several minesweeper helicopters were designed in the USSR. In 1974, the Mi-8BT trawl tug was created. A whole series of trawls were created - heavy, bulky and rather complex units designed for cutting the anchor cables of floating mines and detonating bottom mines with acoustic, magnetic and combined fuses. The trawl was picked up while hanging from the side of a special vessel, delivered to the desired area on a sling, lowered into the water - and work began. The Mi-8BT did not go into mass production, since the specialized Mi-14 marine vehicles turned out to be more suitable towing vehicles.

Installing a bracket for a machine gun in the open cargo door of the Mi-8
Photo: S. Sergeeva

The Mi-8MB, one of the first “flying hospitals” in the USSR, was built in small series. For the first time, equipment was installed on an ambulance evacuation vehicle that made it possible to immediately provide emergency assistance to seriously wounded people, and not just take them out of the battlefield. But the size of the Mi-8 helicopter would not allow it to be used for work in the zone of enemy fire; the all-powerful Customer in the seventies did not show due interest in such machines, and the Mi-8MB also did not receive decent distribution. Subsequently, this work continued on the Mi-8MT.

Greater success accompanied the creation of special sea rescue modifications of the G8, although not immediately. For a long time, Mi-8s (and almost all other types of helicopters) were used to perform search and rescue missions at sea and on land, which were not subject to any modifications. The special sea rescue Mi-8SP appeared in 1976. He could already operate in bad weather, which was the main point of the technical specifications. On its basis, a special Mi-8SPA helicopter was created to lift astronauts in the event of their splashdown, but at that time there was already a more suitable modification of the Mi-14 rotary-wing flying boat.

The Mi-8 cockpit provided good visibility until the armor was installed. But without her, dear, it’s very “uncomfortable” in battle.
Photo: S. Sergeeva

In 1973, the Tupolev Design Bureau created a new tactical reconnaissance complex VR-3 "Flight" with an unmanned aircraft "143". The new technology was appreciated by the troops, but for all its positive qualities it also gave rise to problems. According to the technical specifications, it was necessary to ensure the re-flight of the UAV no more than 4 hours after landing, and the “bird” did not always “return to its nest”, and it had to be found and delivered to the position or to the rear base as soon as possible. This was supposed to be done using the TZM-143 transport-loading vehicle on a car chassis, which was part of the complex, and it was difficult to fulfill this point of the Requirements. It was proposed to introduce an aerial search for the device, and it would be accelerated by a radio beacon that would give signals to the MRP-56 marker receiver and the helicopter’s radio compass. For this purpose, the Mi-8T turned out to be the most convenient. A lifting device LPG-150M and a hinge-pendulum mechanism were installed on it.

After the UAV is detected, the helicopter lands nearby. A special team is preparing the Flight for transportation. The Mi-8 hovers over it, picks up cars on a cable no more than 15 meters long and takes them home at speeds of up to 140 km/h, and with a short 5-meter cable - up to 200 km/h. It was recommended to attach a small parachute to the tail section for stabilization.

After the successful experience with the “Flight” (and the Mi-8 also provided operational operation of the VR-3), it was repeatedly used to test unmanned aircraft and missiles of various tonnage - from very small to quite serious machines weighing a ton or two. They also carried the vehicles after a normal landing, and simply collected the debris, often scattered over many kilometers of the Caspian steppes. Consignments were also landed from the Mi-8 to degas land contaminated with toxic components of rocket fuel. Heptyl, for example, was burned with “barrel” napalm. Difficult, monotonous and sad work...

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A number of original technical solutions were used in the design of the helicopter: large-sized duralumin stampings, adhesive-welded joints, and an automatic engine control system. Compared to the Mi-4, the new helicopter had higher flight characteristics and twice the payload capacity. The first experimental V-8 with one AI-24V engine and a four-bladed propeller from the Mi-4 first took to the air on June 24, 1961 (test pilot B.V. Zemskov). On August 2, 1962, test pilot N.V. Lyoshin lifted off the ground the B-8A prototype with two TV2-117 and a five-blade propeller, and on September 17 its first free flight took place.

In May 1964, assembly of the new passenger V-8AP in the government cabin version was completed. It was almost no different from the V-8AT and served as the basis for testing the modernized AP-34B autopilot and main rotor speed synchronizer. The V-8AP was shown to party and government leaders. In September of the same year, the second stage (“B”) of the joint state testing program began with flights on the V-8AP. Having successfully completed the state testing program, the V-8AP was converted in the spring of 1965 at the pilot production of plant No. 329 into a comfortable version for transporting 28 passengers. By this time, the experimental V-8AP helicopter had been practically brought to perfection, the service life of most of its units reached 500 hours. In June, it was presented at the Paris Aviation Show, where it was highly praised by foreign experts for its excellent flight performance and comfort, and was recognized as one of the most successful middle-class helicopters. The helicopter was demonstrated just as successfully a few months later at an industrial exhibition in Copenhagen. Subsequently, Mi-8 helicopters took part almost every year in all major international air shows and exhibitions, worthily representing the domestic aviation industry in different parts of the globe.

Serial production of the Mi-8 began in March 1965 at aircraft plant No. 387 in Kazan. At the end of the year, the first production samples left the assembly shop. By 1969, the Mi-8 had completely replaced the Mi-4 on the assembly line. In 1970, the Ulan-Uden plant also began producing it.

The Mi-8 helicopter has a single-rotor design with a five-blade, three-hinge main rotor and a three-blade tail rotor. The landing gear is tricycle, non-retractable, with a self-orienting front strut that is fixed in flight. To protect the tail rotor there is a tail support. The Mi-8P helicopter differs from the transport Mi-8T by rectangular windows and the absence of a Doppler antenna for the DIV-1 ground speed and drift angle meter on the tail boom. The cabin of the main version of the Mi-8P has 28 soft passenger seats. The twenty-eight-seat passenger cabin layout became the main one on the production Mi-8P. Only in 1968 it underwent minor modifications. The rear fuselage compartment was changed - a luggage compartment was located in it. The passenger cabin has lengthened by more than a meter. The rear doors were made smaller and a rear entrance door with a ladder was installed in them. The Mi-8P could also be used as an ambulance or transport helicopter for transporting small-sized cargo inside the cabin and large-sized cargo on an external sling. A few years later, based on the Mi-8P and its later modifications, versions with a passenger cabin with 20, 24 and 26 seats were created. The Mi-8P can be used as an ambulance and transport (small-sized cargo inside the cabin, large-sized cargo on an external sling).

In 1968, the fuselage design at the rear was modified. The luggage compartment was located there. The passenger compartment has lengthened by more than a meter. The rear doors became smaller and a rear entrance door with a ladder was installed in them.

In 1962-1991, two factories produced about 5,200 Mi-8 helicopters (3,700 in Ulan-Ude). Of these, about 2,800 were exported to 40 countries. Half of the helicopters produced are still in operation. In 1964-1967, the Mi-8 set 7 international records (mostly by female crews).

Modifications:

V-8A is the second prototype. It featured two engines and a five-bladed propeller.
V-8AP is the fourth prototype. Manufactured in 1964 in the government salon version. In 1965, converted into a passenger version.
Mi-8APS, Mi-8AP-2, Mi-8AP-4 - enhanced comfort options (“salons”). They differ in the engine. TV2-117AG. Produced in Ulan-Ude.
Mi-8M - modernized for 40 passenger seats (project). It was distinguished by an extended fuselage and TV3-117 engines. Developed in 1964-1971.
Mi-8PA - with uprated TV2-117F engines (1700 hp). Certified in Japan in 1980.
Mi-8PS - salon" for 7, 9 or 11 passengers (Mi-8PS-7, Mi-8PS-9, Mi-8PS-11, respectively).
Mi-8S - (the second with this designation) - “salon” based on the Mi-8T. Developed in 1969.

Modification: Mi-8P
Main propeller diameter, m: 21.29
Tail rotor diameter, m: 3.91
Length, m: 18.17
Height, m: 5.65
Weight, kg
-empty: 6800
-normal takeoff: 11100
-maximum take-off: 12000
Engine type: 2 x GTE TV2-117A
-power, kW: 2 x 1257
Maximum speed, km/h: 250
Cruising speed, km/h: 225
Practical range, km: 480
Practical ceiling, m: 4500
Static ceiling, m: 1900
Crew, people: 2-3
Payload: up to 28 passengers or 12 stretchers with attendants or 4000 kg of cargo in the cabin or 3000 kg on the sling.

The prototype B-8A helicopter is the second prototype.

The third B-8A prototype in flight.

The experimental V-8AP helicopter is the fourth prototype. 1964

Experienced helicopter V-8AP.

Mi-8P of the first series in flight.

Mi-8P helicopter. In the background is a Mi-8T.

Mi-8P lands on the site near the Peter and Paul Fortress. Saint Petersburg.

Mi-8P helicopter on the site near the Peter and Paul Fortress.

Mi-8P of Altai Airlines.

Mi-8P of the U Tair company in the parking lot.

Mi-8P comes in for landing.

Government Mi-8PS.

Mi-8P cockpit.

The first version of the Mi-8 helicopter with a four-blade main rotor was tested in 1962. In October 1963, testing began on the second version with a five-blade main rotor, which was put into mass production at the end of 1965.

The Mi-8 is equipped with an anti-icing system that operates in both automatic and manual modes. The helicopter's external suspension system allows it to transport cargo weighing up to 3000 kg. If one of the engines fails in flight, the other engine automatically switches to increased power, while horizontal flight is performed without reducing altitude. The Mi-8 is equipped with an autopilot that provides stabilization of roll, pitch and yaw, as well as a constant flight altitude. Navigation and flight instruments and radio equipment that the helicopter is equipped with allow it to fly at any time of the day and in difficult weather conditions.

The helicopter is mainly used in transport (Mi-8T) and passenger versions. In the passenger version, the Mi-8P is equipped to carry 28 passengers. By special order, in Kazan, a version with a luxury cabin can be manufactured, designed for seven passengers. Orders were completed for B. Yeltsin, N. Nazarbayev, M. Gorbachev and others. The military version of the Mi-8T has pylons for mounting weapons (nursing missiles, bombs). The next military modification of the Mi-8TV has reinforced pylons for hanging a large number of weapons, as well as a machine gun mount in the bow of the cabin. By moving the RV to the left side, its effectiveness was increased.

The Mi-8MT is the latest modification of the helicopter, which was the logical conclusion of the transition from a transport to a transport-combat helicopter. More modern TVZ-117 MT engines with an additional AI-9V gas turbine unit and a dust protection device at the entrance to the air intakes are installed. To combat surface-to-air missiles, there are systems for dispersing hot engine gases, shooting false thermal targets and generating pulsed IR signals. In 1979-1988. The Mi-8MT helicopter took part in the military conflict in Afghanistan.

Helicopter modifications:

Mi-8T (Hip-C)- the main military transport modification.
Mi-8TV- modernized version with enhanced weapons.
Mi-8TVK- export version of the Mi-8TV with 6 Malyutka ATGMs.
Mi-9- a flying command helicopter based on the Mi-8T.
Mi-8SMV- electronic warfare and electronic warfare helicopter.
Mi-8PPA- a modernized version of the Mi-8SMV in the role of a communications helicopter and an electronic warfare helicopter.
Mi-8MT- transport and combat helicopter based on the Mi-8TV (1991).

Performance characteristics of the Mi-8 helicopter:

Year of adoption - 1966.
The diameter of the main propeller is 21.29 m.
The diameter of the tail rotor is 3.91 m.
Length - 18.22 m.
Height - 5.65 m.
Weight, kg
- empty - 7260,
- normal takeoff - 11100,
- maximum take-off - 12200.
Internal fuel - 1450 + 1420 kg.
Engine type - 2 GTD Klimov TV2-117A (TV3-117MT).
Power - 2 x 1710 hp. (2 x 3065 hp)
Maximum speed - 260 km/h.
Cruising speed - 225 km/h.
Practical range - 1200 km.
Range - 465 km.
Practical ceiling - 4500 m.
Static ceiling - 1900 m.
Crew - 2-3 people.

28 passengers or 32 soldiers or 12 stretchers with accompanying persons or 4000 kg of cargo in the cabin or 3000 kg on the sling.

Based on site materials

GENERAL CHARACTERISTICS OF THE MI-8T HELICOPTER

1. GENERAL INFORMATION ABOUT THE HELICOPTER

The Mi-8 helicopter is designed to transport various cargoes inside the cargo compartment and on an external sling, mail, passengers, as well as for carrying out construction, installation and other work in hard-to-reach areas.

Rice. 1.1. Mi-8 helicopter (general view)

The helicopter (Fig. 1.1) is designed using a single-rotor design with a five-blade main rotor and a three-blade tail rotor. The helicopter is equipped with two TV2-117A turboprop engines with a take-off power of 1,500 hp. each, which ensures high flight safety, since flight is possible even if one of the engines fails.

The helicopter is operated in two main versions: the passenger Mi-8P and the transport Mi-8T. The passenger version of the helicopter is designed for interregional and local transportation of passengers, luggage, mail and small-sized cargo. It is designed to carry 28 passengers. The transport option provides for the transportation of cargo weighing up to 4000 kg or passengers in the amount of 24 people. At the request of the customer, the passenger cabin of the helicopter can be converted into a cabin with increased comfort for 11 passengers.

The passenger and transport versions of the helicopter can be converted into an ambulance version and into a version for operation with an external sling.

The ambulance version of the helicopter allows you to transport 12 bedridden patients and an accompanying medical worker. In the version for working with external sling, large cargo weighing up to 3000 kg is transported outside the fuselage.

For long-range helicopter flights, it is possible to install one or two additional fuel tanks in the cargo compartment.

Existing versions of the helicopter are equipped with an electric winch, which allows, using an onboard boom, to lift (lower) loads weighing up to 150 kg on board the helicopter, and also, if there is a pulley system, to pull wheeled loads weighing up to 3000 kg into the cargo compartment.

The helicopter crew consists of two pilots and a flight mechanic.

When creating the helicopter, special attention was paid to high reliability, efficiency, ease of maintenance and operation.

Safety of flights on the Mi-8 helicopter is ensured by:

The installation of two TV2-117A(AG) engines on the helicopter, the reliability of the operation of these engines and the VR-8A main gearbox;

The ability to fly in the event of failure of one of the engines, as well as switch to autorotation mode (self-rotation of the main rotor) in the event of failure of both engines;

The presence of compartments that isolate the engines and the main gearbox using fire partitions;

Installation of a reliable fire protection system that ensures extinguishing a fire in the event of its occurrence, both simultaneously in all compartments and in each compartment separately;

Installation of backup units in the main systems and equipment of the helicopter;

Reliable and effective anti-icing devices for main and tail rotor blades, engine air intakes and cockpit windshields, which allows flight in icing conditions;

Installation of equipment that ensures simple and reliable piloting and landing of a helicopter in various meteorological conditions;

Drive of the main units of the systems from the main gearbox, ensuring the operability of the systems in the event of engine failure:

The ability to quickly leave the helicopter after landing by passengers and crew in emergency situations.

2. BASIC HELICOPTER DATA

Flight data

(transport and passenger options)

Take-off weight (normal), kg.................. 11100

Maximum flight speed (instrument), km/h, 250

Static ceiling, m........................ 700

Instrument cruise speed at altitude
500 m, km/h ……………………………………………220

Economic flight speed (instrument), km/h. 120

fuel 1450 kg, km................................ 365

option with fuel refueling 2160 kg, km. . .620

Flight range (at an altitude of 500 m) in ferry
option with fuel filling 2870 kg, km... 850

Flight range (at an altitude of 500 m) with refueling
fuel 2025 kg (outboard tanks of increased
capacity), km................................................... .. 575

Flight range (at an altitude of 500 m) in ferry
version with fuel filling 2735 kg (outboard tanks

increased capacity), km.... 805

Flight range (at an altitude of 500 m) in ferry
version with fuel refueling 3445 kg (outboard tanks

increased capacity), km.... 1035

Note. Flight range is calculated taking into account 30 minutes of fuel remaining after landing

Geometric data

Helicopter length, m:

without main and tail rotors................... 18.3

with rotating main and tail rotors ...25,244

Helicopter height, m:

without tail rotor................................... 4.73

with rotating tail rotor................ 5.654

Distance from the tip of the main rotor blade to
tail boom when parked, m.................. 0.45

Distance from ground to bottom of fuselage

(clearance), m................................................... ...... 0.445

Horizontal tail area, m 2 ..... 2

Helicopter parking angle................. 3°42"

Fuselage

Cargo compartment length, m:

without cargo doors........................ 5.34

with cargo doors at 1 m from the floor 7.82

Cargo compartment width, m:

on the floor................................................ ... 2.06

for heating ducts........................ 2.14

maximum........................................ 2.25

Cargo compartment height, m.................. 1.8

Distance between power floor beams, m ... 1.52

Escape hatch size, m…………………… 0.7 X1

Loading ramp track, m.................. 1.5±0.2

Passenger cabin length, m............ 6.36

Passenger cabin width (floor), m... 2.05

Passenger cabin height, m 1.8

Seat pitch, m................................................... .... 0.74

Passage width between seats, m... 0.3

Wardrobe dimensions (width, height, depth), m 0.9 X1.8 X 0.7
» sliding door (width, height), m. 0.8 X1.4
» opening, along the rear entrance door in the passenger

option (width, height), m.......... 0.8 X1>3

Size of emergency hatches in passenger compartment

option, m........................................ 0, 46 X0.7

Crew cabin size, m................... 2.15 X2.05 X1.7

Adjustment data

Angle of installation of the main rotor blades (according to the rotor pitch indicator):

minimum................................................. 1°

maximum........................................ 14°±30"

Deflection angle of the trimmer plates of the propeller blades -2 ±3°

» installation of tail rotor blades (at r=0.7) *:

minimum (left pedal all the way) ................... 7"30"±30"

maximum (right pedal all the way)………….. +21°±25"

* r- relative radius

Weight and centering data

Take-off weight, kg:

maximum for transport option…….. 11100

» with a load on an external sling …………… 11100

transport option........................... 4000

on external sling......................... 3000

passenger version (person).......... 28

Empty helicopter weight, kg:

passenger version........................... 7370

transport »................................ 6835

Weight of service load, including:

crew weight, kg................................... 270

» oil, kg................................................... ............. 70

weight of products, kg................................................... 10

» fuel, kg................................................... .......... 1450 - 3445

» commercial load, kg........................ 0 - 4000

Empty helicopter alignment, mm:

transport option........................................... +133

passenger » ..................................... +20

Acceptable alignments for a loaded helicopter, mm:

front................................................... ............. +370

rear................................................... .................... -95

3. AERODYNAMIC AND GEOMETRIC CHARACTERISTICS OF THE HELICOPTER

According to the aerodynamic design, the Mi-8 helicopter is a fuselage with a five-bladed main rotor, three-bladed tail rotor and fixed landing gear.

The main rotor blades are rectangular in plan with a chord equal to 0.52 m. The rectangular plan is considered aerodynamically worse than others, but it is easy to manufacture. The presence of trimmer plates on the blades allows you to change their torque characteristics.

The blade profile is the most important geometric characteristic of the rotor. The helicopter has different profiles along the length of the blade, which significantly improves not only the aerodynamic characteristics of the main rotor, but also the flight properties of the helicopter. From the 1st to the 3rd section, the NACA-230-12 profile is used, and from the 4th to the 22nd - the NACA-230-12M profile (modified) *. The NACA-230-12M airfoil has Mkr = 0.72 at an angle of attack of zero lift. As the angle of attack a° increases (Fig. 1.2), Mcr also decreases at the most favorable angle of attack, at which the lift coefficient C y = 0.6, Mcr = 0.64. In this case, the critical speed in the standard atmosphere above sea level will be:

V KP == a Mkr = 341 0.64 = 218 m/s, where a is the speed of sound.

Consequently, at the ends of the blades it is possible to create a speed of less than 218 m/s, at which shock waves and wave resistance will not appear. At the optimal rotor speed of 192 rpm, the peripheral speed of the blade tips will be:

U = wr = 2 prn / 60 = 213.26 m/s, where w is the angular velocity;

r is the radius of the circle described by the tip of the blade.

Rice. 1.2. Change in the lift coefficient C y from the angles of attack a° and the M number of the NACA-230-12M profile

This shows that the peripheral speed is close to the critical speed, but does not exceed it. The helicopter main rotor blades have a negative geometric twist, varying according to a linear law from 5° at the 4th section to 0° at the 22nd section. In the area between the 1st and 4th sections there is no twist and the installation angle of the blade sections in this area is 5°. Twisting the blade by such a large amount significantly improved its aerodynamic properties and the flight characteristics of the helicopter, and therefore the lift force is more evenly distributed along the length of the blade.

* The compartment from the 3rd to the 4th section is transitional. Main rotor blade profile - see fig. 7.5.

The propeller blades have variable both absolute and relative profile thickness. The relative thickness of the profile c is 13% in the butt, in the area from r = 0.23 to 7 = 0.268 - 12%, and in the area from r = 0.305 to the end of the blade - 11.38%. Reducing the thickness of the blade towards its end improves the aerodynamic properties of the propeller as a whole by increasing the critical speed and Mkr of the end parts of the blade. Reducing the thickness of the blade towards the tip leads to a decrease in drag and a decrease in the required torque.

The main rotor of a helicopter has a relatively large fill factor - 0.0777. This coefficient makes it possible to create greater thrust with a moderate propeller diameter and thereby keep the blades in flight at small installation angles, at which the angles of attack are closer to the most advantageous ones in all flight modes. This made it possible to increase the efficiency of the propeller and delay stalling at higher speeds.

Rice. 1.3. Helicopter rotor polarity in hovering mode: 1 - without ground influence; 2 - with the influence of the earth.

The aerodynamic characteristics of a helicopter main rotor are presented in the form of its polar (Fig. 1.3), which shows the dependence of the thrust coefficient Cp and the torque coefficient tcr on the total pitch of the main rotor<р. По поляре видно, что чем больше общий шаг несущего винта, тем больше коэффициент крутящего момента, а следовательно, больше коэффициент тяги. При наличии «воздушной подушки» тяга несущего винта будет больше, чем без нее при том же шаге винта и коэффициенте крутящего момента.

The tail rotor blades are rectangular in plan with the NACA-230M profile and do not have geometric twist. The presence of a combined horizontal joint of the “cardan” type and a flapping compensator at the tail rotor hub allows for a more even redistribution of the lift force over the surface swept by the propeller in flight.

The helicopter fuselage is aerodynamically asymmetrical. This can be seen from the curves of changes in the coefficients of fuselage lift C 9f and drag coefficient C depending on the angles of attack a f (Fig. 1.4). The lift coefficient of the fuselage is zero at an angle of attack slightly greater than 1, therefore the lift force will be positive at angles of attack greater than G, and negative at angles of attack less than 1. The minimum value of the fuselage drag coefficient C will be at an angle of attack equal to zero. Due to the fact that at angles of attack greater or less than zero the coefficient C f increases, it is advantageous to fly at angles of attack of the fuselage close to zero. For this purpose, a forward tilt angle of 4.5° is provided for the main rotor shaft.

A fuselage without a stabilizer is statically unstable, since an increase in the angle of attack of the fuselage leads to an increase in the coefficient of longitudinal moment, and, consequently, the longitudinal moment acting on pitching up and tending to further increase the angle of attack of the fuselage. The presence of a stabilizer on the tail boom of the fuselage provides longitudinal stability to the latter only at small installation angles from +5 to -5° and in the range of small angles of attack of the fuselage from -15 to + 10°. At large angles of installation of the stabilizer and large angles of attack of the fuselage, which corresponds to flight in autorotation mode, the fuselage is statically unstable. This is explained by the disruption of flow from the stabilizer. Due to the helicopter having good controllability and sufficient control margins in all flight modes, it uses a stabilizer that is not controllable in flight with an installation angle of 6°.

Rice. 1.4. Dependence of the lift coefficient Suf and drag coefficient Схф of the fuselage on the angle of attack a° of the fuselage

In the transverse direction, the fuselage is stable only at large negative angles of attack -20° in the range of gliding angles from -2 to + 6°. This is due to the fact that an increase in the sliding angles leads to an increase in the roll moment coefficient, and consequently, the lateral moment, which tends to further increase the sliding angle.

In terms of direction, the fuselage is unstable at almost all angles of attack at small sliding angles from -10 to +10°; at angles greater than these, the stability characteristics improve. At sliding angles of 10°< b < - 10° фюзеляж нейтрален, а при скольжении больше 20° он приобретает путевую устойчивость.

If we consider the helicopter as a whole, although it has sufficient dynamic stability, it does not cause any great difficulties when piloting even without an autopilot. The Mi-8 helicopter is generally rated with satisfactory stability characteristics, and with the automatic stabilization systems turned on, these characteristics have improved significantly, the helicopter is given dynamic stability in all axes and therefore piloting is significantly easier.

4. HELICOPTER LAYOUT

The Mi-8 helicopter (Fig. 1.5) consists of the following main parts and systems: fuselage, takeoff and landing devices, power plant, transmission, main and tail rotors, helicopter control, hydraulic system, avionics and electronic equipment, cabin heating and ventilation systems , air conditioning systems, air and anti-icing systems, devices for external load suspension, rigging, mooring and household equipment. The helicopter fuselage includes a nose 2 and central 23 parts, a tail 10 and end 12 beams. In the bow, which is the cockpit, there are pilot seats, instrument panels, electric consoles, an AP-34B autopilot, and command control levers. The glazed cockpit provides good visibility; the right 3 and left 24 blisters are equipped with emergency release mechanisms.

In the forward part of the fuselage there are niches for installing containers with batteries, airfield power plug connectors, air pressure receiver tubes, two taxi and landing lights and a hatch with a cover 4 for access to the power plant. The forward part of the fuselage is separated from the central part by connecting frame No. 5N, in the wall of which there is a doorway. A folding flight mechanic's seat is installed in the door opening. At the front, on the wall of frame No. 5N, there are shelves for radio and electrical equipment, at the rear there are containers for two batteries, a box and an electric winch control panel.

In the central part of the fuselage there is a cargo compartment, to enter which there is a sliding door 22 on the left, equipped with an emergency release mechanism. A side boom is attached to the outside of the upper front corner of the sliding door opening. The cargo compartment has folding seats along the right and left sides. On the floor of the cargo compartment there are mooring units and an electric winch. Above the cargo compartment there are engines, a fan, a main gearbox with a swashplate and a main rotor, a hydraulic panel and a consumable fuel tank.

Shock absorbers and struts of the main 6, 20 and front landing gear, and outboard fuel tanks 7, 21 are attached to the fuselage components from the outside. A kerosene heater is located in front of the right outboard fuel tank.

The cargo compartment ends in a rear compartment with cargo doors. In the upper part of the rear compartment there is a radio compartment in which panels for radio and electrical equipment are installed. There is a hatch to enter the radio compartment and tail boom from the cargo compartment. Cargo doors cover the opening in the cargo compartment, designed for rolling in and out of wheeled vehicles, loading and unloading large cargo.

In the passenger version, 28 passenger seats are attached to special profiles located along the floor of the central part of the fuselage. On the starboard side in the rear of the cabin there is a wardrobe. The right side panel has six rectangular windows, the left - five. The rear side windows are built into the emergency hatch covers. The cargo doors in the passenger version are shortened, the luggage compartment is located on the inside of the left door, and the boxes for containers with batteries are located in the right door. There is an opening in the cargo doors for the rear entrance door, consisting of a door and a ladder.

Rice. 1.5 Layout diagram of the helicopter.

1-front chassis leg; 2-nose fuselage; 3, 24-sliding blisters; 4-engine exit hatch cover; 5, 21 main landing gear legs; 6-hood heater KO-50; 7, 12-outboard fuel tanks; 8-hoods; 9-gear frame; 10-central part of the fuselage; 11-hatch cover in the right cargo door; 12, 19-load doors; 13-tail boom; 14-stabilizer; 15-end beam; 16-fairing; 17-tail support; 18-ladders; 20-sash flap; 23-sliding door; 25-emergency hatch-window.

The tail boom is attached to the central part of the fuselage, to the nodes of which the tail support and the uncontrolled stabilizer are attached. The tail shaft of the transmission runs inside the tail boom in its upper part. An end beam is attached to the tail boom, inside of which an intermediate gearbox is installed and the end part of the transmission tail shaft passes through. A tail gearbox is attached to the end beam on top, on the shaft of which a tail rotor is mounted.

The helicopter has a non-retractable tricycle landing gear. Each landing gear is equipped with liquid-gas shock absorbers. The wheels of the front strut are self-orienting, the wheels of the main struts are equipped with shoe brakes, for the control of which the helicopter is equipped with an air system.

The power plant includes two TV2-117A engines and systems that ensure their operation.

To transmit power from the engines to the main and tail rotors, as well as to drive a number of units, a transmission is used, consisting of main, intermediate and tail gearboxes, a tail shaft, a fan drive shaft and a main rotor brake. Each engine and main gearbox has its own autonomous oil system, made according to a direct single-circuit closed circuit with forced oil circulation. To cool the engine oil coolers and main gearbox, starter generators, alternators, air compressor and hydraulic pumps, the helicopter is equipped with a cooling system consisting of a high-pressure fan and air ducts.

The engines, main gearbox, fan and panel with hydraulic units are covered by the hood. When the hood covers are open, free access to the units of the power plant, transmission and hydraulic system is provided, while the open hood covers of the engines and main gearbox are working platforms for performing maintenance of helicopter systems.

The helicopter is equipped with means of passive and active fire protection. Longitudinal and transverse fire partitions divide the engine compartment into three compartments: the left engine, the right engine, and the main gearbox. The active fire-fighting system supplies extinguishing agent from four cylinders to the burning compartment.

The main rotor of a helicopter consists of a hub and five blades. The bushing has horizontal, vertical and axial hinges and is equipped with hydraulic dampers and centrifugal blade overhang limiters. The all-metal blades have a visual spar damage alarm system and an electrothermal anti-icing device.

The tail rotor is a pusher, pitch variable in flight. It consists of a cardan-type hub and three all-metal blades equipped with an electrothermal anti-icing device.

The helicopter's dual control consists of longitudinal-transverse control, directional control, combined "Pitch-throttle" control and main rotor brake control. In addition, there is separate control of engine power and engine shutdown. Changing the overall pitch of the main rotor and longitudinal-transverse control of the helicopter are carried out using a swashplate.

To ensure control of the helicopter, the system of longitudinal, transverse, directional control and collective pitch control includes irreversible hydraulic boosters, for powering which the helicopter has a main and backup hydraulic systems.

The four-channel AP-34B autopilot installed on the Mi-8 helicopter ensures stabilization of the helicopter in flight in roll, heading, pitch and altitude.

To maintain normal temperature conditions and clean air in the cabins, the helicopter is equipped with a heating and ventilation system that supplies heated or cold air to the crew and passenger cabins. When operating a helicopter in areas with a hot climate, instead of a kerosene heater, two on-board freon air conditioners can be installed.

The helicopter's anti-icing system protects the main and tail rotor blades, the two front windows of the cockpit and the engine air intakes from icing.

The anti-icing device for the propeller blades and cockpit windows is electrothermal, and the engine air intakes are air-thermal.

The aviation and radio-electronic equipment installed on the helicopter ensures flights day and night in simple and difficult weather conditions.

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