Today, an office chair is a high-tech product with a large number of different adjustments. Functionality, practicality, wear resistance, comfort, ergonomics and aesthetics are the properties that a high-quality office chair has. Developers, doctors and designers are involved in the development and improvement of office chairs.

A modern office chair consists of a frame - back and seat, armrests, upholstery and filling, gas lift, crosspiece, rollers and mechanism.

Frame

The frame is one of the main structural elements of an office chair. There are two types: monolithic and non-monolithic.

Monolithic - the back and seat form a single frame, which makes the structure of the chair more durable, and such a chair can be used without armrests in cases where the armrests are removable.

Non-monolithic - the back and seat are connected by armrests, a metal plate or other element.

Back

The back of the chair serves as a back support; it can be low or high, the shape of the back is rectangular or rounded.

The angle between the seat and the back of the office chair should be slightly more than 90 degrees, which allows you to relax the lumbar spine when leaning back in the chair.

The cushion on the back of the chair in the area of ​​the lumbar spine helps to evenly distribute the load on the spine and gives an anatomical shape to the backrest, increasing the ergonomic properties of the chair. Sometimes chairs are equipped with a lumbar bolster adjustment system, which creates additional comfort when using them.

The design of some chairs includes a headrest, which allows you to relax the cervical spine.

Adjustment of the back of the chair (the angle of the backrest, fixing the backrest in a certain position, etc.) is carried out using various adjustment mechanisms.

Seat

The seat of an office chair can be hard, semi-soft or soft.

The hard seat is made of elastic flooring materials, such as straw, wood or metal.

The semi-soft seat has a medium thickness of the flooring.

The soft seat has a thick flooring and is equipped with springs.

The downward front edge of the seat should be rounded to prevent disruption of the blood supply to the legs.

The most preferred seat width is 400-480 mm, depth is 420 mm. Seat depth can be adjusted in two ways: by moving the seat or moving the back of the chair.

The ideal chair seat position is with your feet fully on the floor and your knees bent at an angle of 90 degrees. At the same time, the depth of the office chair should ensure such a position of the legs in which the hips fit snugly to the seat and the popliteal fossae do not touch the seat of the chair.

Armrests

The armrests serve as support for the elbows, thereby relieving the load from the shoulders, neck and spine, and reducing arm fatigue. The upholstery on the armrests creates additional comfort when working. The greatest need for armrests is experienced by people who often work a lot at a computer, typing text from a keyboard. The absence of armrests can lead to feeling unwell, fatigue, decreased performance.

Some chairs are equipped with armrests that are adjustable in height, width and angle. If the armrests are not equipped with an adjustment mechanism, they must ensure a position of the arms in which the arms are bent at the elbows at an angle of 90 degrees.

Armrests are attached to the chair frame in different ways:

– The armrests are attached to the seat of the chair. If necessary, they can be removed without compromising the integrity of the chair structure.

– The armrests are attached to the back and to the seat of the chair, connecting them.

– The armrests are attached to the back and to the seat of the chair, connecting them. In this case, the back and seat are fastened to each other with a metal plate or other element. In most cases, the armrests can be removed if necessary without compromising the integrity of the structure.

Upholstery

High-quality wear-resistant materials are used as upholstery for office chairs: synthetic fabrics of various structures and compositions, natural or artificial leather.

Synthetic fabric is a very durable material, quite easy to care for and antistatic. Has good hygroscopicity and breathability, has an aesthetic appearance and a wide variety of textures and colors.

Genuine leather is a wear-resistant, elastic, easy-to-care material. It has good breathability, thanks to this, when using office chairs upholstered in genuine leather, the processes of natural heat exchange between the human body and environment are not violated. Genuine leather differs in the method of dressing, dyeing technology and quality of raw materials.

Faux leather is a practical and durable material that is resistant to ultraviolet rays.

Acrylic mesh is a durable, fairly rigid material that is used to upholster the backs of ergonomic chairs.

Filler

Polyurethane foam or foam rubber are used as filler in office chairs - materials that are very similar to each other. Polyurethane foam is more wear-resistant and durable than foam rubber. Polyurethane padding is made molded (i.e., of the required thickness, shape, with an anatomical profile), and foam rubber is supplied in blocks of different thicknesses, from which the required shapes are cut. Molded polyurethane foam is excellent for the manufacture of backs and seats of chairs, while eliminating the possibility of deterioration in the quality of the product due to the manufacturer's savings on material (thickness or density of padding). In the case of using foam rubber, the quality of the product mainly depends on the integrity of the manufacturer.

Gas lift

A gas lift (gas cartridge) is a steel cylinder filled with inert gas. The gas lift is designed to adjust the height of the chair and acts as a shock absorber.

Gas lifts are short, medium or high. As a rule, short gas lifts are installed on executive chairs, short or medium gas lifts on office chairs, and medium or high gas lifts on children's chairs. All gas lifts have standard mounting dimensions and are interchangeable.

Gas lift can be chrome or black. The black gas lift (the most common) is equipped with a decorative black plastic cover. The chrome-plated gas lift is not supplied with a decorative cover and serves as a continuation of the chrome-plated crosspiece.

Cross.

The crosspiece is the lower part of the chair, which bears the main load. The most stable are crosspieces with a large diameter and a five-beam base equipped with rollers. This design provides maximum mobility in all directions and comfort of movement in the chair.

The reliability of the crosspiece primarily depends on the quality of the material from which it is cast. Crosspieces are made of plastic and metal.

Plastic is an inexpensive but high-quality material with properties close to metal.

Metal, in most cases, chrome-plated, is stronger than plastic and has a more representative appearance. The only drawback of a metal cross is its greater weight compared to a plastic one.

As a rule, the crosspiece and armrests are made in the same material and color, therefore, in the production of crosspieces, inexpensive painted wood is also used to make wooden overlays for the metal frame of the crosspiece.

Rollers.

Casters for office chairs are made from polypropylene, polyamide (nylon) or polyurethane (elastic plastic). Hard and durable rollers made of polypropylene or polyamide are intended for standard floor coverings, and soft rollers made of polyurethane are intended for parquet or laminate. Each manufacturer has different quality standards for rollers, but the sizes of the rollers are usually the same.

Office chair mechanisms

For comfortable use of an office chair, the presence of conveniently located, easy-to-operate adjustment mechanisms is of great importance. Today there is a large number of various mechanisms, which can be divided into several types: simple, complex and swing mechanisms.

Simple mechanisms adjust chairs only in height, for example, the Piastre mechanism. Simple mechanisms are installed on staff chairs.

Rocking mechanisms fix the chair only in the working position, for example, the Top Gun mechanism.

Complex mechanisms make it possible to adjust and fix the chair so as to create the most comfortable conditions for a person during work, maintaining health and ensuring high performance. An example of such a mechanism is the Synchromechanism.

Helicopter fuselage - body aircraft. The helicopter fuselage is designed to accommodate the crew, equipment and payload. The fuselage can house fuel, landing gear, and engines.

In the process of developing the volumetric and weight layout of the helicopter, the configuration of the fuselage and its geometric parameters, coordinates, magnitude and nature of the loads that must be absorbed by the power elements are determined. Selecting the fuselage SSC is the initial stage of design. A power circuit is being developed that most fully fulfills the customer's requirements.

Basic requirements for the fuselage CSS:

reliability of the design during helicopter operation;

ensuring a given level of comfort in the crew and passenger cabins;

high operational efficiency;

ensuring a safe volume inside the fuselage for the crew and passengers and the possibility of leaving it during an emergency landing of the helicopter.

Operational requirements, layout and purpose of the helicopter also significantly influence the choice of fuselage SCS. These requirements are as follows:

• - maximum use of the internal volumes of the fuselage;
• - ensuring the visibility required for the helicopter crew;
• - providing access for inspection and maintenance of all units located in the fuselage;
• - convenient placement of equipment and cargo;
• - ease of loading, unloading, securing cargo in the cabin;
• - ease of repair;
• - sound insulation, ventilation and heating of the premises for passengers and crew;
• - the ability to replace cabin glass under operating conditions;
• - the possibility of re-equipping passenger cabins by changing the layout of the room, the type of seats and the step of their installation.

For emergency exit of the helicopter by passengers and crew, emergency exits are provided on the helicopter. Doors for passengers and crew, as well as service hatches are included

included in the number of emergency exits, if their dimensions and location meet the relevant requirements. Emergency exits in the flight deck are located one on each side of the fuselage, or instead there is one overhead hatch and one emergency exit on either side. Their size and location should ensure that the crew can quickly leave the helicopter. Such exits may not be provided if the helicopter crew can use emergency exits for passengers located near the flight deck. Emergency exits for passengers must be rectangular in shape with a corner radius of no more than 0.1 m.

The dimensions of emergency exits for the crew must be no less than:

480 x 510 mm - for side exits;

500 x 510 mm - for a rectangular top hatch or with a diameter of G40 mm - for a round hatch.

Each main and emergency exit must meet the following requirements:

Have a movable door or a removable hatch providing free exit for passengers and crew;

Easy to open from both inside and outside with no more than two handles;

Have means for locking from the outside and inside, as well as a safety device that prevents the door or hatch from opening in flight as a result of accidental actions. Locking devices are self-locking, without removable handles or keys. On the outside of the helicopter, places are designated for cutting out the skin in the event of jamming of doors and hatches during an emergency landing of the helicopter.

The volumes required to accommodate passengers and transported cargo are decisive in the design of passenger and cargo compartment fuselage.

The appearance of the fuselage and its CBS depend on the purpose of the helicopter and its layout:

An amphibious helicopter must have a special shape of the lower part of the fuselage that meets the requirements of hydrodynamics (minimum loads on the helicopter when landing on water; minimum required thrust of 11B during takeoff; absence of splash formation in the pilot's viewing area and engine air intakes; compliance with stability and buoyancy requirements );

The fuselage of a helicopter crane is a power beam to which the crew cabin is attached, and the cargo is transported on an external sling or in containers connected to the joints of the lower central part of the fuselage;

In the most common single-rotor helicopter design, it is necessary to have a power cantilever beam for attaching the rotor.

The choice of a rational fuselage SCS is carried out primarily on the basis of weight statistics, parametric dependencies and generalized information about the power circuits of previous structures.

According to the results decisions made proposals are formed on the basis of which the final selection of the fuselage CSS is made. In most cases, based on the requirements and operating conditions, it is already known in advance which type of design is applicable in a particular case, so the task can be reduced to searching best option within a given design type.

In frame structures, CSSs that have already been proven by long-term practice are used - these are structures such as reinforced shells (beam scheme), truss structures and their combinations.

The most common beam fuselage design. The main reason for the development of beam fuselages is the desire of the designer to create a strong and rigid structure in which the material, optimally distributed along a given cross-sectional perimeter, is rationally used under various loads. The beam structure makes maximum use of the internal volume of the fuselage, meeting all the requirements of aerodynamics and technology. Cutouts in the skin require local force, which increases the weight of the fuselage.

Beam fuselages are divided into two types - spar and monoblock.

The fuselage layout changes significantly if there are cutouts in the design, especially along their significant length. As the sections approach the end part of the cutout, the stresses in the skin and stringers are significantly reduced, the transmission of torque becomes more complicated, and additional stresses appear in the longitudinal set. To maintain the strength of the panel, the stringers along the cutout boundary are reinforced, turning into spars. The sheathing and stringers are fully engaged only in a section located from the ends of the cutout at a distance approximately equal to the width of the cutout. In such a case, it is advisable to adopt a spar structure for the fuselage SCS.

In spar structures, the bending moment is perceived mainly by longitudinal elements - spars, and the skin perceives local loads, shear force and torque.

In a monoblock structure, the casing, together with the frame elements, also absorbs normal forces from bending moments.

A combination of the specified power circuits are stringer fuselages with partially working skin, which is made in the form of a thin-walled shell, reinforced with stringers and frames. A type of monoblock KSS is.

Monocoque made of homogeneous material. Provides for the presence of only two elements - sheathing and frames. All forces and moments are absorbed by the casing. This scheme is most often used for tail booms of small diameters - D< 400 мм (обшивка, согнутая по цилиндру с малым радиусом, имеет высокую устойчивость при сжатии).

Multilayer monocoque. The use of three-layer panels with thin load-bearing layers makes it possible to increase both local and overall rigidity of fuselage parts with a regular (without cutouts) zone. The structural design of three-layer (laminated) panels is very diverse and depends on the materials of the outer and inner layers, the type of filler, the method of connecting the skins to the filler, etc.

The fuselage surface, used to move technical personnel during ground maintenance of the corresponding units, is made of panels of a layered structure (increased rigidity) with a thickened outer load-bearing layer with a friction coating. These panels must be included and the power circuit of the fuselage.

It is advisable to absorb the load from soft fuel tanks with panels of a layered structure. These panels, having great bending rigidity, simultaneously serve as a tank container, and then there is no need to create an additional load-bearing surface supported by the stringer set of the lower part of the fuselage.

KM has been successfully introduced into the design of helicopter airframes and has already been used on several generations of helicopters.

Modern fiberglass plastics compete with traditional aluminum alloys in terms of specific strength, but are significantly, at least 30% inferior to them in specific rigidity. This circumstance was a brake on the expansion of the use of fiberglass plastics and structural elements.

Organoplastics are lighter materials than fiberglass materials; their specific rigidity is not inferior to aluminum alloys, and their specific strength is 3-4 times greater. The widespread development of organoplastics has made it possible to set a fundamentally new task - to move from creating individual parts from CM to metal structures to the creation of the structure itself from CM, to their expanded use, and in some cases - to the creation of a structure with the predominant use of CM.

CM are used both in the skins of three-layer panels of the tail, wing, fuselage, and in frame parts.

The use of organite instead of fiberglass makes it possible to reduce the weight of the airframe. In heavily loaded units, organoplastics can be used most effectively in combination with other more rigid materials, for example, carbon fiber reinforced plastics.

Structural and technological diagram of the fuselage of the experimental Boeing 360 helicopter, all power elements of which are made of panels of a layered structure using a composite material.

The use of thin skins, well reinforced with honeycomb core (having a low density), makes layered structures a reserve for reducing the weight of the fuselage. High specific strength and resistance to vibration and acoustic loads determine the growing use of such structures as power elements of the fuselage.

The potential advantages of three-layer structures can only be realized if production is organized at a high technical level. The issues of design, strength and technology of these structures are so closely interconnected that the designer cannot help but pay great attention to technological issues.

Long-term strength of glued joints and tightness of honeycomb units (from moisture ingress) are the main things that must be ensured by structural and technological development.

Technological challenges include:

• - choosing a brand of glue that provides the necessary strength with an acceptable weight gain;
• - the ability to control technological conditions at all stages of manufacturing units;
• - ensuring a given degree of coincidence of the contours of the mating parts (mainly the honeycomb block and the frame);
• - application of reliable control methods with gluing strength measurements;
• - choice of additional sealing method;
• - introduction of honeycombs without perforation.

Truss fuselage. In a truss fuselage, the load-bearing elements are spars (truss chords), struts and braces in the vertical and horizontal planes. The skin absorbs external aerodynamic loads and transfers them to the truss. The truss absorbs all types of loads: bending and torsional moments and shearing forces. Due to the fact that the skin is not included in the fuselage load-bearing structure, the cutouts in it do not require significant reinforcements. The presence of rods in the truss structure makes it difficult to use the internal volume of the fuselage, placement of units and equipment, and their installation and dismantling.

Eliminating resonant vibrations of numerous rods is a difficult task. The truss design makes it difficult to meet the aerodynamic requirements for the shape of the fuselage and the rigidity of the skin. In this design it is difficult to apply advanced technology for welding components with complex configurations weld. Heat treating large trusses after welding poses certain challenges. The listed main disadvantages of the truss structure are the reason for their limited use.

The CSS of the cabin floor is determined by the purpose of the helicopter. In a transport helicopter for transporting wheeled vehicles, the cargo floor must be reinforced with longitudinal beams placed in such a way that the loads from the wheels are absorbed directly by these load-bearing elements. To secure wheeled vehicles, units are installed in the floor for fastening bracing cables at the intersection of the longitudinal (stringer) and transverse (frame) frame elements. Monorails mounted on the cabin ceiling are used for loading and unloading containers. The load on cables is attached to a cart attached to the monorail and moves along it to a specified location in the cabin. It is advisable to include monorails in the power structure of the fuselage. Mooring units are also installed in the cargo compartment at the required intervals for the corresponding loads.

For the convenience of loading and unloading large cargo, the cargo ladder (ramp) should be mechanized so that it can stop and lock in any position, and also to ensure the possibility of transporting cargo on an open rear ladder.

The power elements of the fuselage are mainly made of aluminum alloys. Titanium and stainless steel are used in areas exposed to heat. Fairings power plant and the tail transmission (located on top of the tail boom) are rationally made of fiberglass reinforced with reinforced ribs.

When forming the CSS of a frame unit, the following basic provisions must be taken into account:

The distance between the power transverse elements and their placement on the unit is determined by the location of application of concentrated forces normal to the axis of the unit;

All concentrated forces applied to the frame elements must be transferred and distributed to the skin, through which they are usually balanced by other forces;

Concentrated forces must be perceived by frame elements directed parallel to the force - through stringers and spars, and forces acting across these units - by frames or ribs, respectively;

Concentrated forces directed at an angle to the axis of the unit must be transmitted to the casing through longitudinal and transverse force elements. The force vector must pass through the intersection point of the rigidity axes of these elements;

The cutouts in the frame unit must have expansion joints along their perimeter in the form of reinforced belts of longitudinal and transverse elements.

The presence of cutouts in the fuselage load-bearing structure, sharp transitions from one configuration to another, and zones of application of large concentrated forces (i.e., “irregular zones”) have a significant impact on the distribution and nature of the force flow of stresses, which is similar to the fluid velocity field in the region of local resistance.

The stress concentration in the fuselage structural elements, the amplitude and frequency of alternating stresses are the determining parameters in solving the very important problem of creating a high-resource fuselage.

The problem associated with the design of the fuselage can be solved in the following ways:

Develop the CSS taking into account the analysis of the nature and location of the application of external forces and operational requirements that determine all kinds of cutouts (their sizes, locations on the fuselage);

Use thin (moment-free) sheathing, which can lose stability under short-term heavy loads without residual deformation;

Based on sufficient production and operation experience, widely introduce elements made of CM into the practice of constructing frame units.

The final formation of the FCS of the fuselage of minimum mass with a given resource is carried out on the basis of an analysis of the results of experimental studies of the full-scale frame for calculated cases of loading of power elements with a complete simulation of the forces and moments applied to the fuselage.

HELICOPTER AIRframe AND CABIN EQUIPMENT

1. GENERAL INFORMATION

The fuselage is an all-metal semi-monocoque of variable cross-section, consisting of a frame and skin. The fuselage is the base to which all components of the helicopter are attached; it houses the equipment, crew and payload.

The design of the fuselage ensures its operational dissection, which simplifies the repair and transportation of the helicopter. It has two structural connectors (see Fig. 2.16) and includes a nose and central part, a tail boom and an end boom with a fairing.

The main materials of construction are: sheet clad duralumin D16AT made of sheets 0.8 mm thick for the outer cladding, reinforced duralumin B95 and magnesium alloys.

The design of many components uses stampings from aluminum alloys, castings from steel and non-ferrous alloys, as well as extruded profiles. Individual components and parts are made of alloy steel.

Synthetic materials are used for sound insulation and finishing of cabins.

2. FORSE FUSELAGE

Bow The fuselage (Fig. 2.1), which is the cockpit, is a 2.15 m long compartment that houses pilot seats, helicopter and engine controls, instrumentation and other equipment. Its front part forms a canopy that provides visibility to the crew. The crew cabin is separated from the cargo cabin by frame No. 5N with a door.

Sliding blisters 2 are located on the right and left. In the cabin ceiling there is a hatch for access to the power plant, which is closed with a lid that opens upward. The helicopter control levers and pilot seats are located on the floor of the cockpit, and a flight engineer's seat is installed in the opening of the entrance door to the cockpit. Behind the seats, between frames No. 4H and 5H, there are battery compartments and shelves for radio and electrical equipment.

The frame of the bow consists of five frames No. 1N - 5N, longitudinal beams, stringers, stamped stiffeners and a canopy frame. Technologically, the bow is divided into the floor, side panels, ceiling, canopy, sliding blisters and frame No. 5N.

The crew cabin floor (Fig. 2.2) of a riveted structure consists of a set of lower parts of frames, longitudinal beams and stringers. The load-bearing frame is fastened with angle profiles and reinforced with profiles and diaphragms in the places of cutouts and fastening of units.

The flooring and outer cladding made of duralumin sheets are attached to the frame. On top of the flooring along the axis of symmetry, between stringers No. 3, two sheets of corrugated duralumin are installed.

There are hatches in the floor and outer floor cladding for the installation of units, access to the nodes and joints of the helicopter control system rods, to the fastening points of the front landing gear, the connecting bolts of frame No. 5N and the pipes of the heating and ventilation system.

In the outer skin between frames No. 2N and ZN, hatches 10 are made for the installation of landing and taxiing lights MPRF-1A. On Mi-8P helicopters, a second MSL-3 flashing light is installed under the floor of the cockpit between frames No. 4N and 5N.

Rice. 2.2. Cabin floor of the forward fuselage:

1, 5, 6, 11 - holes for helicopter controls; 2 - hole for electrical wiring of the instrument panel; 3 - pads; 4 - hole for the heating system pipe; 7 - hatch for access to the shock absorber of the front landing gear; 8 - installation and inspection hatches; 9 - hatch for a flashing beacon; 10 - hatches for headlights.

To protect the flooring from wear, four pads 3 made of delta wood are installed under the track control pedals. Brackets for attaching seats, helicopter control units, instrument panels and the autopilot console are mounted on the floor.

The side panels are made of stamped stiffeners, profiles and duralumin cladding. Stamped stiffeners together with cast magnesium profiles form the frames of the openings for the right and left sliding blisters.

Rubber profiles are installed along the leading and trailing edges of the openings to seal the cockpit. Outside, on top of the openings and in front of them, there are gutters for water drainage. In the upper part of the frame sealing of the openings, mechanisms for emergency release of blisters are mounted from the inside.

On the right and left sides between frames No. 4Н and 5Н there are compartments for accommodating batteries (two on each side). The compartments are closed from the outside with lids that are locked with screw locks. The covers are hinged and, for ease of use, held in a horizontal position by two steel rods. The compartments have guides along which containers with batteries move. The internal surfaces of the battery compartments are covered with heat-insulating material. BANO-45 aeronautical lights are installed under the blisters between frames No. 1N and 2N. On the left side in front of the battery compartments there are cutouts for airfield power plug connectors 4 (see Fig. 2.1).

The ceiling of the cockpit is made of stamped rigidities, a longitudinal and transverse set of diaphragms, profiles and duralumin lining. The skin is riveted to the frame with special rivets with spike-shaped heads to prevent feet from slipping when servicing the power plant.

There is a hatch in the ceiling for access to the power plant. The design of the hatch and cover provides protection against water entering the cockpit.

The hatch cover of a riveted design is attached to two hinges 1 (Fig. 2.3). A spring lock is built into the first hinge, which automatically locks the lid in the open position. When opening the lid, the profiled rib 10 with its beveled section presses the axis of the latch 13 until the axis, under the action of the spring 12, moves to the straight section of the rib, after which the hatch cover is locked.

Rice. 2.3. Exit hatch to the power plant:

1 - hatch hinges; 2 - stops; 3 - lock button; 4 - fork; 5 - adjusting coupling; 6 - shaft, 7 - latch; 8 - hook; 9 - handle; 10 - profiled rib; 11 - locking pin; 12 - spring; 13 – clamp.

When closing the hatch cover, you must first press on the protruding end of the latch and move the axle beyond the profiled edge of the hinge. In the closed position, the hatch cover is secured with a lock. The lock mechanism consists of a handle 9 with a locking device, a fork 4, an adjusting clutch 5 and a shaft with two claws 6. When opening the hatch cover, you need to press the lock button 13, remove the latter from engagement with hook 5, after which the handle is turned down. In this case, the shaft will rotate clockwise, and the paws will release the cover. For visual monitoring in flight of the condition of the engine air intake tunnels, there are two inspection windows in the hatch cover. Sealing of the hatch in the closed position is ensured by rubber gaskets, which are pressed with a special profile attached along the perimeter to the hatch. If the seal of the hatch is broken, elimination is carried out by adjusting clutch 5 of the lock control rod.

Frame No. 5N. The forward part of the fuselage ends with a docking frame No. 5N (Fig. 2.4). The frame is a duralumin wall edged around the perimeter with a pressed corner profile, the end beam of which forms a flange for joining with the central part of the fuselage. The wall is reinforced with a longitudinal and transverse set of corner profiles. Along the axis of symmetry, an opening was made in the frame wall for the entrance door to the cockpit. The opening is edged with a pressed duralumin corner, to which a rubber profile is secured with screws.

Shelves for installing equipment are attached to the front wall of the frame on both sides of the doorway. On the left side of the wall at the top and bottom there are holes for the passage of rods and helicopter control cables. Special plates are installed on the right and left sides of the wall of frame No. 5N from the side of the cargo compartment to ensure flight safety. A casing with removable covers is attached to the rear left side of the wall of frame No. 5H, enclosing the helicopter control rod and rocker system and electrical harnesses. A folding seat is attached to the casing. In the transport version, on the right side of the doorway on the side of the cargo compartment, a box is riveted to the wall in which containers with batteries 3 are placed (see Fig. 2.1). The box is equipped with guides and is closed with lids with screw locks.

The cockpit door is made in the form of a duralumin plate. It is suspended on hinges and equipped with a lock with two handles, and on the side of the cockpit there are two locks - latches. An optical micro-eye is installed at the top of the door. In the doorway between frames No. 4N and 5N there is a folding seat for an on-board technician with seat belts.

The cockpit canopy consists of a frame and glazing. The frame of the lantern is assembled from duralumin profiles, stiffeners and facing frames, fastened together with screws and rivets.

Rice. 2.4. Frame No. 5N

The canopy is glazed with oriented organic glass, with the exception of two front windshields 1 (see Fig. 2.1) (left and right), made of silicate glass, which are electrically heated and equipped with windshield wipers. The glass is edged along the perimeter with rubber profiles, inserted into magnesium cast frames and pressed through the duralumin lining with screws and special nuts. After installation, to ensure tightness, the edges of the frames inside and outside are coated with VITEF-1 sealant.

The blister (Fig. 2.5) is a frame cast from magnesium alloy into which convex organic glass 14 is inserted. The glass is secured to the frame with screws through a duralumin lining 11 and a rubber sealing gasket. The blisters are equipped with handles 12 with locking pins 7, connected to levers 13 by cables 8. The left and right blisters can only be opened from the cockpit.

The blisters are moved back along the upper and lower guides made of special profiles.

The upper internal guide profiles 5 are mounted on balls that are located in steel cages. The outer U-shaped guide profile 6 has brackets with eyes for the locking pins of the emergency blister release mechanism and drilling in 100 mm increments for pin 7 of the lock for fixing the blister in extreme and intermediate positions. At the bottom of the blister frame there are grooves in which lower guide profiles 9 fastened with screws to the opening frame slide along felt pads.

Each blister can be emergency reset using a handle located above the blister inside the flight deck. To do this, the handle must be pulled down, then under the action of springs 1, the locking pins 2 will come out of the eyes of the brackets 3, after which the blister must be pushed out. The lower profiles of the opening frames have slots for supplying hot air to the blisters. A visual icing sensor is installed at the bottom of the left blister.

Rice. 2.5. Sliding blister:

1 - spring; 2 - locking pin; 3 - bracket; 4 - emergency release handle for blisters; 5 - internal guide profiles; 6 - external guide profile; 7 - pin; 8 - cable; 9 - lower guide profiles; 10 - felt pad; 11 - facing; 12 - handle; 13 - lever; 14 - glass; 15 - outer handle of the blister.

3. CENTRAL PART OF THE FUSELAGE

General information. The central part of the fuselage (Fig. 2.6) is a compartment located between frames No. 1 and 23. It consists of a frame, working duralumin skin and power units. The frame consists of a transverse and longitudinal set: the transverse set includes 23 frames, including frames No. 1 and 23 - docking frames, frames No. 3a, 7, 10 and 13 - power, and all other frames of lightweight construction (normal). The longitudinal set includes stringers and beams.

The frames provide the specified shape of the fuselage in cross section and perceive loads from aerodynamic forces, and the power frames, in addition to the above loads, perceive concentrated loads from the helicopter units attached to them (chassis, main gearbox power unit).

Technologically, the central part is assembled from separate panels: cargo floor 15, side panels 3.5 and ceiling panel 4, rear compartment 7.

Rice. 2.6. Central part of the fuselage:

1 - front landing gear shock absorber mounting unit; 2 - sliding door; 3 - left side panel; 4 - ceiling panel; 5 - right side panel; 6 - main landing gear shock absorber mounting unit; 7 - rear compartment; 8 - cargo hatch doors; 9 - attachment point for the main landing gear strut; 10 - attachment point for the axle shaft of the main landing gear leg; 11, 12, 13, 14 - attachment points for the outboard fuel tank; 15 - cargo compartment floor panel; 16 - attachment point for the strut of the front chassis leg.

a - hole for the air intake pipe from the cargo compartment; b - hole for the thermal air pipeline; c - hole for the heating and ventilation system box; g - spare units; d - attachment points for tie-down straps of outboard fuel tanks; e - attachment point for the mooring device.

In the central part, between frames No. 1 and 13, there is a cargo compartment ending at the rear with a cargo hatch, and between frames No. 13 and 21 there is a rear compartment with cargo doors 5. Behind frame No. 10 there is a superstructure that smoothly turns into a tail boom. In the passenger version, the compartment between frames No. 1 and 16 is occupied by the passenger compartment, behind which there is a luggage room. The engines are located above the cargo compartment between frames No. 1 and y, and the main gearbox is located between frames No. 7 and 10. The superstructure between frames No. 10 and 13 houses a consumable fuel tank, and between frames No. 16 and 21 there is a radio compartment.

Rice. 2.7. Frames of the central part of the fuselage:

a - power frame No. 7; b - power frame No. 10; c - power frame No. 13; g - normal frame; 1 - upper beam; 2 - side part; 3 - fitting; 4 - lower part; 5 - arched part; 6 - mooring ring.

All other frames, except for the connecting frames, are made of composite frames, including an upper part, two side parts and a lower part. These parts of the frames, as well as the stringers, are included in the design of the panels and during assembly, the parts of the frames are joined together, forming the load-bearing frame of the central part of the fuselage.

The most loaded elements of the central part of the fuselage are frames No. 7, 10 and 13, as well as the floor panel. Power frames No. 7 and 10 (Fig. 2.7) are made of large stampings of AK-6 alloy, pressed and sheet parts, which form a closed profile, including an upper beam 1, two sidewalls 2 and a lower part 4.

The upper beam consists of two parts connected by steel bolts in a plane of symmetry. At the corners of the beams there are holes for bolts for fastening the main gearbox frame.

The joining of the upper beam of frame No. 7 with the sidewalls is made using milled combs and two horizontally located bolts, and the joining of the sidewalls of frame No. 10 with the upper beam is made using a flange and vertically located bolts. The lower parts of frames No. 7 and 10 consist of walls and 4 corners riveted to it, forming an I-beam profile in cross-section. At the ends of the beams, connecting fittings 3 stamped from AK-6 alloy are installed, with which the lower beams of the frames are joined to the sidewalls with steel bolts.

On the outer part of frame No. 7, steel mounting points for outboard fuel tanks are installed on both sides. On frame No. 10, combined units are installed for simultaneous fastening of the shock-absorbing struts of the main landing gear and the mooring device. In addition, rear mounting points for outboard fuel tanks are installed in the lower part of the frame on both sides.

Frame No. 13 of riveted construction is made of sheet duralumin and pressed angle profiles. The lower part of the frame is made of three stampings of AK-6 alloy, bolted together. With the sides of the frame, the lower part is riveted using fittings, which have holes for installing mooring rings 6. An inclined frame is attached to the lower part of frame No. 13, closing the cargo compartment and being the power edging of the cargo hatch. It has two units installed on each side for attaching cargo doors.

In the upper part of frame No. 13 there is an arched part 5, which is included in the fuselage superstructure; it is stamped from sheet duralumin and has grooves for the passage of stringers.

Lightweight (normal) frames (see Fig. 2.7) are similar in design and have a Z-shaped cross-section. The upper and side parts of the frames are stamped from sheet duralumin and connected end-to-end with overlays. Along the internal contour, the frames are reinforced with an angle profile, and along the external contour, grooves are made for the stringers.

The lower parts of normal frames have upper and lower chords made of angle and T-sections, to which a wall made of sheet duralumin is riveted. At the ends of the lower parts of the frames, fittings stamped from AK-6 alloy are riveted, with the help of which they are riveted to the sidewalls of the frames.

Outside, on the starboard side on frame No. 8, on the left side between frames No. 8 and 9, as well as on frame No. 11, and on both sides there are units installed for attaching straps of outboard fuel tanks. At the bottom of the lower parts of the frames, overhead units made of ZOKHGSA steel are installed for attaching the chassis. On frame No. 1 along the longitudinal axis of the helicopter there is a fastening unit for the front shock absorber strut, and on the sides of the frame and the longitudinal beams of the floor there are riveted units with spherical sockets for the jack supports. On frame No. 2 there are attachment points for the struts of the front landing gear. On frame No. 11 there are fastening points for the axle shafts, and on frame No. 13 there are fastening points for the struts of the main landing gear.

In the ceiling panel between frames No. 7 and 13, as well as in the side panels, stringers made of special D16T duralumin corner profiles with chamfers are installed to improve gluing with the skin. The remaining stringers are installed from angle profiles.

The cargo floor (Fig. 2.8) of a riveted structure consists of the lower parts of the frames, longitudinal beams 11, stringers, flooring made of corrugated sheet 338 AN-1 and outer duralumin cladding. The middle longitudinal part of the flooring, located between frames No. 3 and 13, is reinforced with transverse rigid elements and fastened with screws and anchor nuts to special longitudinal profiles. On top of the flooring along the sides of the floor, corner profiles made of D16AT and L2.5 duralumin sheets are riveted, with the help of which the side panels are connected to the floor of the cargo compartment. Floor load zones from transported wheeled vehicles are reinforced with two longitudinal trough-shaped profiles. To secure the transported cargo on the floor along the sides, 27 mooring units 5 are installed.

Frames and beams in places where mooring units are installed have stamped brackets and fittings made of AK6 alloy. On frame No. 1 along the axis of symmetry of the cargo floor there is a node 1 for attaching the rollers of the LPG-2 electric winch when pulling cargo into the cabin. At the installation site of the LPG-2 electric winch on the wall of the longitudinal beam

a stamped fitting made of AK6 alloy is reinforced, in the shelf of which there are two threaded holes for bolts for fastening plate 2 under the base of the LPG-2 electric winch. A casing is installed on the floor between frames No. 1 and 2 to protect the rollers and cables of the LPG-2 electric winch, and in the opening of the sliding door there are two holes for fixing the removable entrance ladder.

In the walls of the longitudinal beams of the cargo floor at frame No. 5, as well as in the wall of frame No. 1 at the starboard side, there are holes for pipelines 12 of the cabin heating and ventilation system. The walls around the holes are reinforced with stamped edgings made of AK-6 alloy. Cradles for additional fuel tanks are installed on the left and right sides of the floor between frames No. 5 and 10.

Rice. 2.8. Cargo compartment floor panel:

1 - mounting unit for electric winch rollers; 2 - plate for the base of the electric winch; 3 - mooring points; 4 - hatch for the ARK-9 antenna; 5, 8 - hatches to shut-off valves of the fuel system; 6 - installation hatch; 7 - hatch to the latch of the cable for retracting the external suspension; 9, 17, 23 - technological hatches; 10 - hatch for the ARK-UD antenna; 11 - floor frame beams; 12 - heating system pipeline; 13 - attachment points for the shock absorber struts of the front landing gear; 14 - niche for the ARK-9 antenna frame; 15 - cutouts for pipelines of additional fuel tanks; 17 - external suspension attachment points; 18 - supports for hydraulic lifts; 19 - attachment points for the struts of the main landing gear; 20 - hatch for monitoring connections of fuel system pipelines; 21 - attachment points for the axle shafts of the main landing gear; 22 - front landing gear shock absorber mounting unit.

In the cargo floor between frames No. 5 and 6 there are attachment points for the ARK-9 frame antenna, and between frames No. 8 and 9 there are attachment points for the antenna amplifier and the ARK-UD antenna unit.

The flooring has installation and technological hatches, closed with covers on screws with anchor nuts. Along the axis of symmetry in the removable part of the flooring there are hatches 4 for inspection and access to the ARK-9 frame antenna, fuel valves 5 and 8, the antenna unit and the ARK-UD antenna amplifier and the handle for fixing the external suspension in the retracted position.

On Mi-8T helicopters of the latest series, a hatch is made in the cargo floor between frames No. 8 and 9 for the passage of external cable slings with a lifting capacity of 3000 kg.

When working with an external suspension, the hatch has a guard. The cable external suspension units are located inside the cargo compartment on the upper beams of frames No. 7 and 10. In the stowed position, the suspension rises to the ceiling of the cargo compartment and is attached with a DG-64M lock and a cable to a special bracket installed between frames No. 10 and 11. The cargo slings are laid in cargo door box. The guard folds up and is secured with rubber shock absorbers behind the back of the landing seat in the left cargo door. The hatch in the floor of the cargo compartment is closed by paired (inner and outer) covers from the cargo compartment.

The side panels (see Fig. 2.6) are riveted from the side parts of (normal) frames, stringers from angle profiles and duralumin sheathing. The rear parts of the panels end with an inclined frame. On the right and left panels there are five round windows with convex organic glass, except for the first left window, glazed with flat organic glass. The glass is secured to cast magnesium frames with screws and special nuts and sealed along the contour with rubber gaskets, and the edges of the frames are coated with sealant after installing the glass inside and out.

On the left side of the panel between frames No. 1 and 3 there is an opening for sliding door 2, edged with a frame made of duralumin profiles. At the top of the doorway on the cargo compartment side, knots for a rope ladder are installed, and a water drainage gutter is attached to the outside above the doorway.

The door (Fig. 2.9) of a riveted structure is made of a frame and outer and inner skins riveted to it, installed on the lower and upper guides, along which it slides back on balls and rollers. The upper guide 11 is a U-shaped profile into which a slide 14 and two rows of balls 12 are installed. Brackets 15 are riveted to the slide, which are connected to the door with locking pins 13 installed on the door. In the open position, the door is held by a spring clamp mounted on the outside of the fuselage.

Rice. 2.9. Sliding door:

1 - latch; 2 - pin spring; 3, 4 - handles for emergency door release; 5 - cable; 6 - glass; 7 - internal door handle; 8 - springs; 9 - latch; 10 - outer door handle; 11 - upper guide; 12 - ball bearings; 13 - locking pin; 14 - skid; 15 - bracket; 16 – roller.

The door has a round window with flat organic glass and is equipped with two locks. On the front edge of the middle part of the door there is a key lock with two handles 10 and 7 (external and internal).

A pin lock is mounted in the upper part of the door, for emergency release of the door, with internal and external handles 3 and 4. The upper lock is connected to the middle lock by cable wiring, and when the upper lock is opened, the middle lock also opens at the same time. In case of emergency release of the door, you need to turn the outer or inner handle back in the direction of the arrow, while the locking pins 13 of the upper lock come out of the holes of the brackets, and the latch 9 of the middle lock is disengaged by cable 5, after which the door should be pushed out.

To prevent spontaneous opening of the door during flight, a device is installed on it that fixes the door in the closed position.

The ceiling panel (Fig. 2.10) consists of the upper parts of the frames, stringers and sheathing, riveted together. In lightweight (normal) frames, notches are made for the passage of stringers, and on frames No. 3, 3a, 7, 10, the stringers are cut and joined through toothed strips of duralumin sheet. The covering of the ceiling panel between frames No. 1 and 10 is made of titanium sheet, and between frames No. 10 and 13 is made of duralumin sheet. In the covering of the ceiling panel between frames No. 9 and 10 there are holes for the angles of the fire hydrants of the fuel system, and between frames No. 11 and 12 there is hatch 6 for the fuel pumps of the supply tank. Gutters made of pressed profiles are installed on the casing and holes are made for drainage pipelines for water drainage.

On top of the frames of the ceiling panel there are nodes installed: on frame No. 3 - four nodes 1 for mounting engines, on frames No. 5 and 6 - nodes 2 and 3 for fastening the engine fixing device with the gearbox removed, on frames No. 6 and 7 - nodes 5 for fastening frame No. 1 hood, assembly 4 for fastening the hood struts and the fan.

The rear compartment 7 (see Fig. 2.6) is a continuation of the central part of the fuselage and, together with the cargo doors, forms the rear contours of the fuselage. The rear compartment of the riveted structure consists of the upper arched parts of the frames, stringers and outer skin.

Technologically, the compartment is assembled from separate panels and is a superstructure located on top of the cargo compartment, smoothly turning into the tail boom. The superstructure ends with docking frame No. 23.

At the top between frames No. 10 and 13 there is a container for a consumable fuel tank. Between frames No. 16 and 21 there is a radio compartment; in its lower part, between frames No. 16 and 18, there is a hatch for entry from the cargo compartment into the radio compartment and into the tail boom.

On frames No. 12, 16 and 20, fittings are installed at the top for the transmission tail shaft supports. The rear compartment is joined to the ceiling and side panels using corner profiles and external linings.

The skin of the central part of the fuselage (Fig. 2.11) is made of D16AT duralumin sheets with a thickness of 0.8 mm, 1.0 mm and 1.2 mm. The most loaded is the covering of the ceiling panel between frames No. 7 and 13, where the thickness of the covering is 1.2 mm. The covering of the left panel of the superstructure in the area between frames No. 19 and 23 is made of 1 mm thick sheet.

The cargo doors (Fig. 2.12) are located between frames No. 13 and 21 of the central part of the fuselage, suspended on two hinges each to an inclined frame.

Cargo doors close the rear opening in the cargo compartment and create additional cabin volume. The doors are of riveted construction, each consisting of stamped rigidity and outer duralumin cladding. For the convenience of loading wheeled vehicles, the doors have flaps 13 that fold up, which are hinged to the lower parts of the doors. In the folded position, the flaps are held in place by rubber shock absorbers.

The cargo doors are opened and closed manually; in the open position they are held by struts, and in the closed position they are fixed with pins at frame No. 13 and locked with longitudinal and transverse locks 10 and 11. The locks allow the doors to be opened from inside the cargo compartment.

Rice. 2.10. Ceiling panel:

1 - engine mounts; 2,3 - attachment points of the engine fixation device; 4 - attachment point for struts of frame No. 1, hood and fan; 5 - attachment points for frame No. 1 of the hood; 6 - hatch to the booster pumps of the supply tank; a - holes for the main gearbox frame mounting bolts.

On the end surfaces of the doors along the entire perimeter, rubber profiles are reinforced, ensuring sealing of the connecting surfaces of the doors with the fuselage and among themselves in the closed position. To prevent the cargo doors from opening when the helicopter is parked, a locking device for the inner door lock handle is installed outside; Before departure, you need to unlock the handle.

Tool boxes 12 are installed in the lower part of the doors. Both doors have hatches for removing exhaust gases from the running engine of the transported equipment in the cargo compartment. On the left wing there is a portable fire extinguisher 16 and brackets for fastening the supports under the racks 17 of the sanitary stretcher. In the outer skin there are hatches cut out for the blinds with the exhaust ventilation damper 1 and for the flare launchers 2. On the right flap there is a hatch closed with a lid for supplying the ground heater hose 6.

The right wing is equipped with a hatch for leaving the helicopter in an emergency. The hatch is closed with a cover 8, which consists of outer skin and rigidity riveted together. At the bottom, the hatch cover is held by latches, and at the top - by locking pins of the emergency release mechanism mounted on the cover.

The emergency release mechanism is similar in design to the sliding blister mechanism of the cockpit. To reset the cover, you need to sharply pull handle 7 down, then the locking pins will come out of the bracket eyes and release the cover, and the spring pushers located in the upper corners of the hatch will push the cover out.

The helicopter is equipped with 15 ladders designed for loading and unloading wheeled vehicles and other cargo. In the working position, the ladders are fixed with steel units in steel sockets on the lower beam of frame No. 13, in the stowed position they are laid and secured on the floor on both sides of the cargo compartment. Depending on the load of the helicopter, if it is impossible to place cargo ladders on the cabin floor, the ladders are placed on the left wing of the cargo hatch, where attachment points for the ladders are provided in the stowed position.

Rice. 2.12. Cargo doors:

1 - exhaust ventilation damper; 2 - rocket launcher; 3 - folding seat; 4 - crew cab door; 5 - electric winch; 6 - hatch for supplying the ground heater hose; 7 - release handle of the emergency hatch cover; 8 - emergency hatch covers; 9 - handle; 10 - pin lock; 11- turnbuckle; 12 - tool box; 13 - shield; 14 - seat; 15 - ladders; 16 - portable fire extinguisher; 17 - bracket for fastening sanitary racks.

The ladder frame consists of a longitudinal and transverse strength set. The longitudinal load-bearing set consists of two beams riveted from angle profiles and a D16T L1, 2 duralumin wall. The upper chords of the beams are made of a D16T duralumin T-profile, the shelf of which protrudes above the ladder skin and prevents wheeled vehicles from rolling off the ladders when loading and unloading. The transverse set consists of T-profiles and stamped diaphragms made of duralumin sheet riveted to them.

The front and rear edges of the ladders have steel edges. To prevent wheel slipping of self-propelled vehicles when loading them under their own power, corrugated linings are riveted to the edges of the ladders at the rear ends.

Rice. 2.11. Plating of the central part of the fuselage

4. TAIL BOOM

The tail boom ensures the creation of the shoulder necessary for the tail rotor thrust to compensate for the reaction moment of the main rotor.

The tail boom (Fig. 2.14) is of riveted construction, beam-stringer type, has the shape of a truncated cone, consists of a frame and a smooth working duralumin skin.

The frame includes longitudinal and transverse strength sets. The transverse force set consists of seventeen frames of a Z-shaped section. Frames No. 1 and 17 are connecting frames; they are made of extruded D16AT duralumin profile and reinforced with toothed strips. Frames No. 2, 6, 10 and 14 are reinforced in the upper part for supports 3 of the transmission tail shaft. Brackets 2 are also attached to them for installing textolite guide blocks for the tail rotor pitch control cables.

The longitudinal set consists of 26 stringers No. 1 to 14, starting from the top on either side of the vertical axis. The stringers are made of extruded angle profiles.

The casing of the tail boom is made of clad sheet duralumin D16AT. The joints of the sheathing sheets are made along the stringers and frames with an overlap and undercut. In the skin between frames No. 13 and 14, on both sides of the tail boom, cutouts are made for the passage of the stabilizer spar.

Rice. 2.14. Tail boom:

1 - connecting flange; 2 - bracket for fastening the tail rotor control cable blocks; 3 - transmission tail shaft support; 4 - adjustment bracket assembly; 5 - overlay; 6 - stabilizer linkage bracket; 7 - attachment point for the tail support shock absorber; 8 - attachment points for the tail strut strut.

Reinforcing duralumin linings 5 ​​are riveted along the contour of the cutouts. On top of the casing there are hatches with covers for inspecting and lubricating the splined couplings of the transmission tail shaft. Between frames No. 3 and 4 there is a cutout for the MSL-3 flashing beacon, between frames No. 7 and 8, 15 and 16 there are cutouts for combat lights, between frames No. 11 and 12 there is a cutout for the directional system sensor.

The antenna fairing of the DIV-1 device is installed at the bottom of the tail boom between frames No. 1 and 6. The upper part of the fairing is riveted from duralumin profiles and sheathing, and is attached to the beam with screws. The lower part is made of radio-transparent material, fixed to the upper part on a ramrod rod and locked with two folding locks and three plates with screws. Two antennas (receiving and transmitting) of the RV-3 radio altimeter are installed on the lower part of the beam. On frame No. 13 of both sides of the beam, units 4 are installed for the bolts of the stabilizer adjustment brackets, and on frame No. 14 there are brackets 6 for attaching the stabilizer. On frame No. 15, on both sides of the tail boom, there are riveted nodes 8 for attaching the tail strut struts, and on frame No. 17 from below there is a node 7 for attaching the tail strut shock absorber.

5. END BEAM

The end beam (Fig. 2.15) is designed to move the axis of rotation of the tail rotor into the plane of rotation of the main rotor in order to ensure equilibrium of moments of forces relative to the longitudinal axis of the helicopter.

Rice. 2.15. End beam:

1 - frame No. 3; 2 - frame No. 9; 3 - fixed part of the fairing; 4 - spar wall; 5 - tail light; 6 - inclined antenna; 7 - removable part of the fairing; 8 - cover; 9 - keel beam.

The end beam of the riveted structure consists of a keel beam 9 and a fairing. In frame No. 2, the axis of the beam has a bend at an angle of 43° 10" relative to the axis of the tail boom.

The keel beam frame consists of a transverse and longitudinal set. The transverse set includes nine frames. Frames No. 2, 3 and 9 are reinforced, and frame No. 1 is a connecting frame.

The longitudinal set consists of spar 4 and stringers made from corner profiles. The riveted spar is made of D16T duralumin corner profiles, the walls are made of duralumin sheet. At the bottom of the spar wall there is a hatch for access to the intermediate gearbox. The frame of the keel beam is sheathed with smooth working cladding made of D16AT duralumin, 1 mm thick on the right side, 1.2 mm thick on the left side. Between frames No. 1 and 3, a reinforced 3 mm thick D16AT duralumin skin is installed, on the inside of which there are longitudinal millings made using a chemical method to make it easier. A similar 2 mm thick skin is riveted between frames No. 8 and 9.

Docking frame No. 1 is stamped from aluminum alloy D16T; to increase the reliability of the joint, the thickness of the joining planes is increased to 7.5 mm with their subsequent mechanical processing.

Reinforced frame No. 3 (item 1) bracket, stamped from aluminum alloy AK6, the intermediate gearbox is attached to it with four bolts, and the tail gearbox is attached to the flange of frame No. 9. At the top of the bend of the beam there are two hatches - upper and lower. The upper hatch is intended for filling oil into the intermediate gearbox, and the lower hatch is for inspecting the spline joint. The hatches are closed with covers in which there are gill slits for air intake for cooling the intermediate gearbox. During operation, both hatches are used to install the device when measuring the fracture angle between the tail and end shafts of the transmission.

The fairing forms the rear contour of the keel beam and is a fixed rudder that improves the directional stability of the helicopter. The fairing is made of two parts - the lower 7 is removable and the upper 3 is non-removable. The fairing frame consists of six stamped stringers made of D16AT duralumin, six ribs and connecting strips riveted along the contour of the fairing.

The frame is covered with smooth duralumin sheathing. At the bottom of the fairing there is a hatch, in the cover 8 of which there are gill slits for the exit of air cooling the intermediate gearbox. In addition, inclined antennas 6 are mounted on both sides, and whip antennas are mounted along the axis of symmetry of the fairing. A tail light is installed at the rear along the axis of symmetry of the fairing. The removable part of the fairing is attached to the keel beam spar belts with screws and self-locking nuts, and the non-removable part is secured with rivets using butt tapes.

Fig.2.16. Scheme of fuselage joining with standard

connection of docking frames (below)

The joining of fuselage parts is of the same type and is carried out along the joining frames in accordance with the diagram (Fig. 2.16). All docking frames are made of extruded D16AT duralumin profile, the end flange of which forms a flange with holes for docking bolts.

To reduce the stress concentration in the skin, duralumin toothed strips are laid along the contour of the connecting frames, which are riveted together with the skin to the outer flange of the frame.

6. STABILIZER

The stabilizer is designed to improve the longitudinal stability and controllability of the helicopter. The stabilizer (Fig. 2.17) is installed on the tail boom between frames No. 13 and 14; its installation angle can only be changed when the helicopter is parked on the ground.

The stabilizer has a symmetrical profile NACA-0012 and consists of two halves - right and left, symmetrically located relative to the tail boom and interconnected inside the beam.

Both halves of the stabilizer are similar in design. Each half of the riveted stabilizer consists of a spar 2, seven ribs 5, a tail stringer 12, a diaphragm, a front duralumin skin 6, a removable end fairing 9 and a fabric skin 11.

The ribs and diaphragms are stamped from sheet duralumin. The ribs have bow and tail sections, which are riveted to the spar belts. On the flanges of the tail parts of the ribs there are ridges with holes for sewing on the fabric covering.

The tail stringer, made of sheet duralumin, covers the tails of the ribs from below and above and forms a rigid trailing edge of the stabilizer. The tails of the ribs with the tail stringer are blind-riveted.

Rice. 2.17. Stabilizer:

1 - stabilizer mounting axis; 2 - spar; 3 - adjusting bracket; 4 - connecting flange; 5 - rib; 6 - duralumin sheathing; 7 - beam antenna mounting unit; 8 - balancing weight; 9 - end fairing; 10 - drainage hole; 11 - linen covering; 12 - tail stringer.

On the toe of rib No. 1 of each half of the stabilizer there is riveted bracket 3 with an earring, with which you can change the installation angle of the stabilizer on the ground.

A balancing weight 8 weighing 0.2 kg is riveted to the front part of rib No. 7, covered by a removable end fairing 9 made of fiberglass. At the toe of rib No. 7 of the right and left halves of the stabilizer, a unit 7 is installed for attaching the cord of the beam antenna.

The spar of the beam-type stabilizer of riveted structure consists of upper and lower chords and a wall with flanged holes for rigidity. The upper and lower chords of the spar are made of duralumin corner profiles. In the root part, the spar is reinforced with a plate riveted to the chords and the spar wall on the rear side, and in the front part between ribs No. 1 and 2, the spar is reinforced with a plate riveted to its chords. A connecting flange 4, stamped from aluminum alloy, is riveted to the cover plate.

On the spar near rib No. 1 there are fittings with axles 1 for attaching the halves of the stabilizer to the tail boom. The stabilizer linkage units are protected from dust by covers, which are secured to the spar and rib No. 1 with a cord and a clamp using a foam boss.

The nose part of the stabilizer is sheathed with duralumin sheets made of D16AT, riveted along the flanges of the nose parts of the ribs and the spar belts. The tail section is covered with AM-100-OP fabric, the seams along the ribs are sealed with serrated tapes.

The joining of the right and left halves of the stabilizer is done with bolts along the mating flanges and connecting plates.

The chairs are designed to be placed in and performed functional responsibilities pilot, accommodation of passengers, ensuring a comfortable flight, as well as tolerance of overloads by the pilot and passengers of the helicopter in the event of an emergency landing.

Our seats are so compact that they fit in almost all cabins.

The chairs not only meet safety requirements, but also have improved ergonomic characteristics.

When creating the chair, the following goals were achieved:

• weight loss
• cost reduction
• compactness
• maximum ergonomics and comfort
• original design

The chair has an exclusive, modern design. During development, new original engineering solutions were introduced. The production process involves the use of advanced, innovative materials.

The chair is a serial product and has interchangeable components and parts. The seat equipment is easily installed on board the helicopter and is located both along the flight and against the flight. Each chair is reliable in operation and, under normal operating conditions, requires minimal operating costs.

The design of the chair can withstand high impact loads, with less weight, compared to competitor chairs.

Lightweight chairs provide energy savings, and along with safety, economical operation and high ergonomic characteristics.

The multi-stage safety system of our helicopter seat reduces the possibility of injury to the passenger and helps preserve his life. Energy absorption technology has a high level of reliability and effectively absorbs impact energy in the event of a severe accident or emergency landing.

Energy-absorbing helicopter seat, designed for overload up to 30g.

Single-use energy absorption element.

One of the seat modifications provides the ability to install and adjust the degree of impact energy absorption, depending on the weight characteristics of the passenger (optional).

The retention and fixation system consists of: two waist belts, two shoulder belts with inertial reels, a belt fixation lock, a belt length adjustment system and seat belt attachment points.

The chair cushions are designed with minimal displacement (sinking) and dynamic feedback from the seated person. The pillows are made of self-extinguishing material in accordance with AP27.853.

The design of the chair provides for the installation of armrests (optional).

The introduction of a high degree of safety of the chair did not affect the main parameters, such as low weight, comfort, accessibility and maintainability.

SPECIFICATION

THE CHAIR CONSISTS OF:

• Chair frame
• Soft pillows
• Shock absorption systems with attachment points
• Shock absorption adjustment system depending on the passenger's weight (optional)
• Armrests (optional)
• Headrest
• Harness system
• Power supply (optional)
• Literary pocket
• Case (textile/leather) with pre-selected color scheme

SERVICE

Quickly detachable elements:

• Softness
• Cases

Nodes using adjustment:

• Armrest