The fuselage of the helicopter
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The fuselage of the helicopter

The fuselage of the helicopter

The fuselage of the helicopter - the airframe. The fuselage of the helicopter is designed to accommodate the crew, equipment and payload. The fuselage can be placed fuel, chassis, engines.

During the development of the volume and weight are determined by the layout configuration of the fuselage of the helicopter and its geometrical parameters, location, size and nature of the loads which have to be perceived strength members. Selecting KCC fuselage is the initial stage of construction. It worked out such a power scheme that best serves to your requirements.

the fuselage of the helicopter

Basic requirements for the CMP of the fuselage:

  • structural reliability during operation of the helicopter;

  • to ensure a predetermined level of comfort in the cockpit and the passengers;

  • high operating efficiency;

  • Security for the crew and passengers of volume within the fuselage and the possibility of evacuation in an emergency landing of the helicopter.

Performance requirements, scheme and purpose of the helicopter also significantly influence the choice of KSS fuselage. These requirements are as follows:

  • - The maximum use of internal volumes of the fuselage;
  • - providing the review required for the helicopter crew;
  • - providing access for inspection and maintenance of all units located in the fuselage;
  • - convenient placement of equipment and goods;
  • - ease of loading, unloading, fixation of cargo in the cabin;
  • - ease of repair;
  • - sound insulation, ventilation and space heating for passengers and crew;
  • - the possibility of replacing cab glass in the field;
  • - the possibility of re-equipment of passenger cabins by changing the layout of the room, the type of seats and the step of their installation.

The fuselage of the helicopter H-21-metal

The fuselage of the helicopter H-21-metal

For emergency evacuation of the helicopter passengers and crew in a helicopter provided emergency exits. Doors for passengers and crew, as well as maintenance hatches included

In the number of emergency exits, if their size and location meet the relevant requirements. Emergency exit in the cockpit is located one on each side of the fuselage, or instead there is one upper hatch and one emergency exit on either side of the fuselage. Their size and location should ensure the rapid escape of the helicopter by the crew. Such exits can be omitted if the crew of the helicopter can take emergency exit for passengers located near the cockpit. Emergency exit for passengers must be of rectangular shape with a radius of curvature of corners no more than 0,1 m.

The size of emergency exits for the crew must be at least:

  • - 480 x 510 mm - for side exits;

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

the fuselage of the helicopter 1

Each main and emergency exits must meet the following requirements:

  • - Having movable or removable door hatch, which provides free access of passengers and crew;

  • - easy to open both from the inside and outside with no more than two handles;

  • - have means for locking outside and inside, as well as a safety device, excluding the opening of a door or hatch in flight as a result of accidental actions. Locking devices make self-locking, without removable handles and keys. On the outside of the helicopter, there are designated places for cutting the skin in case of jamming of the doors and hatches during an emergency landing of the helicopter.

The volume required to accommodate passengers' cargo transported, are critical in the design of the passenger and the cargo compartment of the fuselage.

Appearance fuselage and CBS depends on the destination of the helicopter and its circuit:

  • - Amphibious helicopter must have a special form of the lower part of the fuselage that meets the requirements of hydrodynamics (minimum loads on the helicopter when landing on water; the minimum required thrust 11B during take-off; no splash formation in the field of view of the pilot and engine air intakes; compliance with the requirements of stability and buoyancy);

  • - the fuselage of the 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 butt nodes of the lower central part of the fuselage;

  • - in the most common single-rotor scheme of a helicopter it is necessary to have a power cantilever beam for fastening the RV.

the fuselage of the helicopter 12

Choice of rational KCC fuselage made primarily on the basis of the weight of statistics, parametric dependencies and summarizes the main circuit prior structures.

As a result of decisions taken form the proposals on the basis of which there is a final selection of the KCC fuselage. In most cases, based on the requirements and the operating conditions are already known in advance what type of design apply in either case, so the problem can be reduced to finding the best option within the specified construction type.

The framework structures are used already tested by long practice KSS - a type design of reinforced shells (beam design), trusses, and combinations thereof.

The most common beam design of the fuselage. The main reason for the development of fuselages beam - the desire to create a sound designer and a rigid structure, in which the material is optimally distributed over the perimeter of a given section, is used efficiently at different loads. The beam structure as much as possible use of the internal volume of the fuselage, provided all the requirements of technology and aerodynamics. Cutouts in the skin require local effort, which increases the weight of the fuselage.

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

The fuselage scheme significantly modifies when there are cutouts in the design, especially at their considerable length. As the cross sections approach the end part of the voltage cutout in the skin and stringers, the torque transmission becomes more complicated, additional stresses and longitudinal set-up appear. To maintain the strength of the panel, stringers along the cutout edge become stronger, turning into spars. The lining and stringers are fully included in the work only of the section located from the ends of the cutout at a distance equal to the width of the cutout. The KSS of the fuselage in this case is expedient to take the spar.

the fuselage of the helicopter 1 233

The spar structures bending moment is perceived predominantly longitudinal members - spars and cladding perceives local load, shear force and torque.

The monobloc paneling together with the elements of the framework also takes a normal effort of bending moments.

The combination of these power schemes are part of a fuselage stringer stressed skin, which is performed in a thin-walled shell, reinforced by stringers and frames. KCC is a kind of one-piece.

The monocoque of a homogeneous material. It provides for the presence of only two elements - plating and frames. All the forces and moments perceives paneling. This scheme is most commonly used for the tail beam of small diameter - D <400 mm (lining, bent on a small radius of the cylinder, has a high compressive resistance).

The monocoque layered. The use of sandwich panels is, thin bearing layers improves both local and overall rigidity of the fuselage with a regular (without cuts) area. Constructive execution trehsloyiyh (sloychatyh) panels is very flexible, and depends on the materials of the outer and inner layer, type of aggregate, the connection method skins with a filler, etc.

The surface of the fuselage, used to move the technical staff at the respective ground handling units are made of panels sloychatoy design (high rigidity) with a thick outer layer of bearing friction coating. These panels are to be included, and a power circuit fuselage.

the fuselage of the helicopter 1321

The load on the soft fuel tanks it is advisable to take the panels sloychatoy design. These panels, having high rigidity pas bending simultaneously acts as a container tank, and then did not want to create an additional bearing surface rests on the stringer set lower fuselage.

The helicopter airframe CM successfully implemented and operated for several generations of helicopters.

Modern glass-competitive with conventional aluminum alloys in terms of specific strength, but significantly, at least in 30% inferior to them in specific stiffness. This circumstance was a brake on the expansion of the volume of the PA application of fiberglass and structural elements.

Organoplastic - lighter than fiberglass materials with specific stiffness are not inferior to aluminum alloys, and in specific strength in 3-4 times their superior. The widespread development of organic plastics allowed to deliver fundamentally new task - to go from the creation of the individual parts of the CM for the metal structures to the creation of the design of the Cabinet, to their extended use, and in some cases - to create a design with a predominant use of KM.

KM used as the skins in the sandwich panels of feathers, wings, fuselage, and the frame member.

Application organita instead of fiberglass to reduce weight of the glider. In heavily loaded organoplastics units can be used most effectively in combination with other longer rigid materials, for example, • CFRP.

Structurally-technological scheme of the fuselage of the helicopter pilot Boeing-360, all security elements are made of panels sloychatoy design using composite materials.

the fuselage of the helicopter 1333

The use of thin skins, well supported with honeycomb core (having a low density), makes sloychatye design reserve weight reduction of the fuselage. High specific strength and resistance to vibration and acoustic loads determine the growth of the application of such structures as load-bearing elements of the fuselage.

Potential advantages of sandwich structures can be implemented only if the production is organized on a high technical level. Questions of design, technology and strength of these structures are so closely interrelated that the designer can not pay more attention to technological issues.

Long-term strength of glued joints and sealing the cell aggregates (from moisture) - the main thing that should be provided constructive and technological development.

For technological tasks include:

  • - the choice of the brand of glue, providing the necessary strength with an acceptable weight gain;
  • - the ability to control technological regimes 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);
  • - the use of reliable control methods with measuring the strength of gluing;
  • - the choice of the method of additional sealing;
  • - introduction of honeycombs without perforation.

The fuselage of the helicopter 111

Truss fuselage. In the fuselage truss scheme power elements are the spars (farm belts), racks and braces in the vertical and horizontal planes. Sheathing perceives external aerodynamic loads and transfers them to the farm. The farm accepts all kinds of loads: bending and torques and shear forces. Due to the fact that the skin is not included in the fuselage power circuit, the cutouts in it do not require significant reinforcement. The presence of rods in the truss structure makes it difficult to use the internal volume of the fuselage, the placement of units and equipment, their installation, dismantling.

the fuselage of the helicopter Mi-1

Eliminating resonant oscillations numerous rods - a difficult task. Truss structure hinders the aerodynamic requirements for the form and the rigidity of the fuselage skin. In this structure, it is difficult to apply the advanced technology nodes welding with a complex configuration of the weld. Heat large farm after welding is connected with certain problems. These truss main shortcomings are the cause of their limitations.

The CCA of the cabin floor is determined by the purpose of the helicopter. In a transport helicopter for the carriage of wheeled vehicles, the cargo floor must be supported with longitudinal beams arranged so that the loads from the wheels are perceived directly by these power elements. To fix the wheeled vehicles in the floor, the nodes are installed to fix the rope cables at the intersection of the longitudinal (stringer) and transverse (frame) frame members. For loading and unloading containers used monorails installed on the ceiling of the cabin. The cargo on the cables is attached to the trolley, which is fixed to the monorail, and moves along it to the specified place in the cabin. Monorails should be included in the power scheme of the fuselage. In the cargo cabin, also mooring units are installed with the required interval for the corresponding loads.

For easy loading and unloading of bulky cargo must mechanize the loading bridge (ramp) so that he could stop and lock in any position, as well as to allow the transport of cargo on the open rear ramp.

Load-bearing elements of the fuselage are mainly made of aluminum alloy. In places exposed to heat, is used titanium and stainless steel. Fairings powerplant and tail transmission (located on top of the tail boom) efficiently perform fiberglass reinforced reinforced ribs.

In the formation of CIL frame unit should consider the following main points:

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

  • - all concentrated forces applied to the frame elements should be transferred and distributed to the casing, through which they are usually balanced by other forces;

  • - concentrated forces should be perceived by the frame elements, directed parallel to the force, - through stringers and spars, and the forces acting across these aggregates - respectively by frames or ribs;

  • - 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 stiffness axes of these elements;

  • - cuts in the frame unit should have compensators in their perimeter in the form of reinforced belts of longitudinal and transverse elements.

The fuselage of the helicopter 222

The presence of cutouts of the fuselage power structure, abrupt transitions from one configuration to another and areas of application of large concentrated forces (ie, “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 area of ​​local resistance.

Stress concentration in the elements of the fuselage structure, the amplitude and frequency of the alternating voltage are decisive parameters for solving a very important problem of creating vysokoresursnyh fuselage.

Solve the problems associated with the design of the fuselage, in the following ways:

  • - to develop KCC taking into account the analysis of the nature and location of external forces and operational requirements that determine all kinds of cuts (their sizes, locations on the fuselage);

  • - apply thin (without moment) lining, which can lose stability under short-term high loads without permanent deformation;

  • - on the basis of sufficient production and operation experience, widely introduce elements made of CM into the practice of designing frame assemblies.

The final formation of CIL minimum mass of the fuselage with a given resource is carried pa based on experimental results of full-scale framework for settlement cases of the loading force elements with full imitation attached to the fuselage of forces and moments.

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