Wing helicopter. Helicopter with wings.
Depending on the application requirements of the wing are formed, which the constructor must perform the development of the CMP airfoil. On the basis of selected parameters of the structure.
Wing can be fitted on the screw VTOL to perform the following tasks:
- Unloading NV in order to increase the speed of horizontal helicopter flight (at the same time can serve as a wing mast for the suspension of special installation, fixing landing gear and placement of fuel tanks);
- HB mount helicopter transverse scheme and its unloading and level flight, fixed landing gear and placement of fuel tanks;
- HB mount on the converted transverse VTOL schemes of tilt-rotor and the creation of the lift in horizontal flight.
Depending on the purpose of the wing changes the magnitude and nature of the load on the power components and the requirements for its construction.
With increasing speed, the screw flight VTOL increased demands of aerodynamics, stability, controllability and aeroelasticity, which affect the aerodynamic configuration of the wing, its degree of mechanization and rigidity.
Aerodynamic requirements include minimum interference and HB wing hover and maximum aerodynamic efficiency at cruising mode.
The rigidity of the wing torsion and bending should be such as to prevent harmful effects of static and dynamic aeroelasticity.
FORMATION KCC WINGS
Selecting CIL wing helicopter essentially depends on its functional purpose and nature of the load.
For helicopters transverse schemes and similar types of convertible YES tilt-rotor wing choice of parameters it depends on the phenomenon of "air" resonance. If the wing is mounted on a helicopter unloading NV, the main requirement is to ensure the strength and resources of its consoles loaded with distributed variable wind load. For a stable flight in autorotation unloading HB wing at cruising speed should not exceed 15-20%.
The aerodynamic load on wing are dynamic. Under the terms of balancing the helicopter and layout considerations, the wing is set by HB. As a result, in the vertical plane of the wing are pulsating loads. Their size and frequency determined by the specific load on HB W), HB speed with the number of blades z, HB excess relative to the wing H-wing plan (scope / restriction, wing area S). The variable part of the aerodynamic forces creates a fatigue stress in the elements of the wing structure, defining its resource.
Helicopters are used for unloading HB cantilever monoplane wings without mechanization.
Placing the wing relative to the fuselage by the requirements of aerodynamics, the volume layout of the fuselage at the junction of the wing, the QRS main landing gear, operational considerations and the security of the crew during the emergency landing of the helicopter.
Selecting CIL wing is determined by a number of conditions:
- - The nature of the load concentrated forces and the time and location of their applications;
The speed and range of the helicopter, respectively). Therefore designer selects parameters wing other considerations (in particular, wing and interference HB).
Selecting KCC cantilever wing
Wing is a beam loaded with distributed and lumped forces. The frame of the wing is made up of longitudinal and lateral recruiting and skin. Are set to the longitudinal spars, stringers and longitudinal walls. The cross consists of a set of ribs. The bending moment M produces axial forces (normal voltage) set in the longitudinal and in the skin. Torque M and transverse force Q causes shear stresses in the casing and the walls of the side members.
Of the three forces acting in cross-sections of the wing, acting as a bearing surface, the core is bending moment. Mass force elements which receive this point, about half the total weight of the wing.
Depending on what elements of the power is mainly perceived by the bending moment, the power circuits are divided into wing spars and packaged.
Wing spar. The power scheme called the wing spar, if the bending moment generally accepted zones spars. The wing has a powerful belts spars, stringers comparatively weak and subtle trim.
Sometimes (for example, the suspension container with rockets) can be calculated case load on the wing of the jet thrust rocket jammed, creating a torque relative to its center of stiffness. There will be a defining torsional stiffness of the wing.
Depending on the number of spars distinguish single, double and mnogolonzheronnye wings.
In single-spar wing Structures are spar, the rear wall (sometimes referred to as an auxiliary spar), lining, ribs, and stringers. The spar is located, usually at the maximum height of the profile, as In this case, for a given bending moment required the smallest area zones. The wall of these wings is to create a closed circuit section.
From an operational point of view, the best are single-spar and two wing spars. They are more convenient to explore the design, they are relatively easy cuts are made in the skin.
The power circuit of the root portion of the spar of the wing depends largely on the conditions of the layout of the fuselage (stowage, cabin, landing gear and others. The side walls must pass through the fuselage, closing the load on the wing panels.
The presence of power components inside the fuselage wing creates difficulties in implementing the desired cabin layout.
The most widely used designs, which spars, stringers and paneling continues in the area occupied by the fuselage. In some instances, the structure where all the longitudinal members, except spar, are cut off at the side of the fuselage. Structures of the first type are superior because Lined with reinforcing elements of the fuselage near the full works at a bend. The main disadvantage of the design of the second type - defective work on the bending of the stringers and skin near the fuselage. The normal stresses in the skin and the supporting elements are practically no longitudinal cross section of a rib-board because of its low rigidity. As the distance from the fuselage normal stresses increase. At a distance approximately equal to the distance between the spars, stringers and trim bending wing fully perceive.
The normal force of the wing box skin and stringers perceived only in part of the circuit, such as toe or, as usual, the middle portion. The rest of the circuit with a thinner skin and less supported by stringers in the bending part is much smaller. In these schemes, spars with strong belts are absent, and for sensing the wall shear forces are connected with plating weak zones. In all the elements of the wing box panels operate uniformly compressed zone.
For the same weight of the wing of the scheme will have greater torsional rigidity than single-spar wing. At light loads on the wing caisson scheme is inferior in quality single-spar weight.
The monoblock wing normal forces in bending perceived skin and the supporting stringers around the contour of its cross-section.
When monobloc scheme wing through the fuselage center section extends nearly the entire round of concentration (except for the tail section). When decompression circuit passes through the fuselage of a caisson.
Monoblock and decompression scheme used on the wings of a large specific surface load. The main advantages of one-piece wing: high rigidity, vitality and a more rational use of elements of their design. However, the gain in weight in these structures compared to the spar is obtained only in the absence of large cuts. The presence of cut-outs dramatically reduces the wing. In the area of panel cut off from work. To preserve the strength of the wing cut-out has to okantovyvat reinforced profile, ie, essentially put spar.
Comparison of the spar and wing caisson power schemes shows that each has its advantages and disadvantages. So sometimes some parts of the wing structure (for example, end portion) performed by decompression scheme, and in the area of the recesses - on the spar.
Reinforced ribs transmit local concentrated forces on the belt of the spar units arranged in a wing or on the external sling. Reinforced ribs mounted in the plane of the connector on the center wing and consoles.
Sheathing, supported by stringers, takes air load is transmitted primarily in the ribs. These in turn transmit it to the wall member. For example, the action of the vertical components of the local air load rib tends to move upwards. This is prevented by the wall of the spar, resulting in them having distributed shear force. In general, in the walls of their resultant spar does not coincide with the resultant of the external air loads. As a result, the rib tends to rotate, balancing the flow of tangential forces from the skin. Tangential forces the walls of the fuselage longerons balanced pas.
Of great importance in the design of a set of longitudinal wing has a selection of design-process-type panel in tension and compression zones of the wing. For bottom panels defining a resource.
An investigation of the choice of the permissible stresses for the individual elements of the power structure depends not only on the material characteristics and design solutions, organizational rules of operation. It should also take into account the way of routine inspections of potentially vulnerable areas of design, their frequency, etc.
To assess the survivability of the bottom panel are important characteristics of crack propagation velocity in dependence on the type of design data on the effectiveness of various limiters cracks etc. Survivability design requirements lead to the need to study the residual strength of the structure in the destruction of one of the panels along the chord.
For the upper surface of the wing that type of reinforcements must provide maximum critical stress at a minimum weight of the material of construction.
The box and the wing spars with stringer set the distance between the ribs should be chosen so that the stringer and paneling in the compressed zone had a value at which both came to the local and overall buckling.
KCC WINGS CONNECTORS
To meet the operational and technological requirements of the wings are made removable. Connectors are used to separate the wings from the fuselage of the helicopter for transport, storage in a warehouse, assembly equipment, repair and other. The wing typically has two connections by which the center section and is divided into two arms. Split wings, regardless of how the connection parts heavier than non-detachable.
Connector design depends on the power circuit of the wing, they are very diverse, but in principle can be reduced to two types:
- Point connector, wherein only the longitudinal spars and wing walls are interconnected;
- Loop connector, in which all power elements of the wing are connected to each other.
In spot power socket connection between the parts of the wing through the nodes, only the junction belts spars. Sheathing, stringers and longerons wall directly with each other is not connected. Therefore, they are fully included in the perception of the bending moment is only at some distance from the terminal.
The smallest amount of butt nodes is three. The bending moment in this case perceived slice bolts connecting respective main belt member. Lower ear usually performed massive because it works on a break.
The auxiliary spar (rear panel) joined with the structure or the fuselage center section by a hinge, perceiving only the shear force, normal force of bending in the plane of the wing chord from the action and reaction torque. As the distance from the connector due to changes in the skin, he gradually included in the bend and at a distance from the connector works almost full. The axis of the bolt connection must coincide with the axis of the stiffness of the wing section.
Torque wing is balanced concentrated in butt joints forces constituting a pair, so the rib on the connector to be reinforced.
The loop connector is most typical for the wing box, with a relatively thick, backed by a well casing. When loop connection connector commonly performed power connection to the upper and lower zones of the caisson. With this power components in the connector and close it completely involved in the perception of bending and twisting moments and shear force.
The design of the loop connector resembles a flange connection. The most widespread construction of the loop connector when the power connection plating and stringers made using connecting profiles, tightening bolts, located in special pits. Connecting surface profiles for a snug fit to each other mechanically treated so that the bending moment in the compressed zone of the wing is transmitted uniformly emphasis butt profiles. In the given design solution junction with bolts running on the slice. The use of cone bolts and split sleeves with inner taper provides interchangeability consoles and fixed joints.
PERFORMANCE cutout in the wing panel
To approach to sets of equipment for mounting and dismounting the fuel tanks and other purposes in various wings are made cutouts. They break the continuity of the power elements and thereby affect its operation. The degree of influence depends on the size of the cut, the type of power influence, constructive design etc cutout. Small cut-outs with little compensation virtually no effect na deformation and stress state of the structure. Compensation small cuts achieved by edging their respective profiles and plates forming the flat frame. Such cuts are closed easily removable covers that are designed to maintain the shape and density of the adjoining performed quite tough.
Large cut-outs are of two types - compensated and uncompensated.
Full payment of large cuts made by setting the removable power panels of equal strength with the cut portions of the wing. Compound removable panels with the broken wing restored power connection and provide a full transfer of bending and torsion. Removable panels heavier construction wing. Their assembly and disassembly require the installation of the wing to the relaxed position.
If the wing skin is relatively thin and poorly supported by, the simplified design of removable panels. In this case, they are attached with screws on a path ensuring a transfer of tangential forces. Lost due to notch bending stiffness ua restored appropriately strengthening belts spars.
Large uncompensated cutouts in the wing have to do in places that require frequent access. They significantly impair the design, besides large areas of skin with supporting elements near the edges of the cut-out is defective involved in the bending. Therefore, the payment of such cuts is associated with radical changes in the power circuit of the wing (production of additional ribs, etc.). The panels covering the uncompensated cuts are carried out not by force, but they should have sufficient strength and rigidity to the perception of the local air loads.
When designing the wing should seek to have the lowest possible number of cuts, especially on the lower surface. Cutouts useful to have a single line along the wing span and as far as possible from places transverse joints. With this their placement easier to provide the necessary increase in places cuts and a smooth flow of power flow.
The choice of material
The main requirement in determining the choice of material for the stretched surface of the power set of wings, is to provide a resource. For these surfaces use force wing set-proven aluminum alloy D16T. The alloy has good endurance and vitality, not very sensitive to the hubs and the internal stresses generated during assembly. The introduction of high purity alloy D16CHT improves the properties listed above.
The choice of alloy for the upper wing of the power set to be decided depending on the scheme and operating conditions, determine the magnitude and repeatability of the loading of the upper panels tensile and compressive loads. The power can be set is made of high-strength aluminum alloys and zinc-based (native V95T alloy). The use of this alloy enables the calculation of the static strength of a significant weight savings.
For nodes, which receive concentrated loads, high-strength materials are used.
Types of connections and fasteners
Select the type of joints and fasteners for the wing it depends on the requirements of the necessary resources. The resource is mainly determined by regular endurance zone. Endurance regular zone depends on the longitudinal seam (fastening the panels to the spars, fastening of panels or sheets of skin together, fastening the stringers to the skin). Without special measures, which reduce the stress concentration around the holes, the desired resource can only be achieved by reducing stress, and this causes an increase in weight of the wing structure.
Selection of a particular constructive solutions (form fastener tension value, etc.) depends on the required resource. This decision should take into account:
- - The possibility of stress corrosion caused by interference and boarding (choice of material and heat treatment of parts of the power set is determined by these considerations);
- - The risk of fretting corrosion;
- - The economic factor: the use of certain compounds, are very effective in terms of improving the structure of endurance, is a rise in the cost structure (cost of manufacturing of fasteners and installation), that the expediency of their application must be confirmed by a special economic calculations.
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