Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C3/00—Wings
  • B64C3/24—Moulded or cast structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C31/00—Aircraft intended to be sustained without power plant; Powered hang-glider-type aircraft; Microlight-type aircraft
  • B64C31/028—Hang-glider-type aircraft; Microlight-type aircraft

Definitions

• the present invention relates to an ultralight aircraft having a low weight, commonly termed "ultralight”, made of composite material, and to a method for manufacturing said aircraft.
• Ultralight aircraft commonly termed "ultralight”
• Low-weight aircraft particularly those having a gross weight of less than 450 kg, can be conventionally used outside the scope of current statutory provisions which regulate the use of ordinary aircrafts.
• ultralights are structurally derived from motorized hang-gliders and are therefore usually formed by a frame-like structure of tubes connected to each other for example by welding, with aerodynamic surfaces made of thermoplastic fabric, for example dacron.
• Ultralight aircrafts of this type are generally used by enthusiasts in their spare time; their performance is very limited both in terms of payload and of speed and their safety conditions are unstable.
• ultralight aircrafts manufactured by using conventional aircraft construction methods, for example by assembly performed by riveting or welding metal plates made of light alloy.
• a principal aim of the present invention is therefore to provide a monocoque ultralight aircraft made of advanced composite material.
• an object of the present invention is to provide a monocoque ultralight aircraft that is unusually strong and safe.
• Another object of the present invention is to provide a monocoque ultralight aircraft having simplified maintenance.
• Another object of the present invention is to provide a method for manufacturing the monocoque ultralight aircraft according to the invention.
• Another object of the present invention is to provide a device that is highly reliable and relatively easy to manufacture at competitive costs.
• an ultralight aircraft characterized in that it comprises a monolithic outer shell that constitutes the fuselage of said aircraft and a monolithic inner shell that constitutes the interiors of said fuselage, said inner shell being assembled to said outer shell to form a single monolithic structure, monolithic wings and tail planes being assembled to said outer shell.
• figure 1 is a perspective view of a multipart mold for producing the fuselage of the monocoque ultralight aircraft according to the invention
• figure 2 is a front transverse sectional view of the fuselage executed by closing the multipart mold shown in figure 1
• figure 3 is a sectional view of a detail of figure 2, illustrating in detail the various layers that compose the fuselage of the monocoque ultralight aircraft according to the invention
• figure 4 is a sectional view of a detail of the fuselage, in which a metal insert embedded in the various layers that constitute said fuselage is provided
• figure 5 is a perspective view of a multipart mold for producing the ultralight aircraft according to the invention
• figure 6 is a longitudinal sectional view of the wings, which are formed by closing the multipart mold
• figure 6a is a detail view of the sectional view of figure 6
• figure 7 is a sectional
• FIG. 1 illustrates a multipart mold for forming an outer shell that constitutes the self-supporting monolithic fuselage 100 of the aircraft.
• the mold comprises a left half-mold 1 and a right half-mold 2.
• the left half-mold 1 is used to form the left half of the fuselage 100 of the ultralight aircraft according to the invention, whereas the right half-mold is used to form the right half of the fuselage 100.
• the two half-molds 1 and 2 are closed together and kept in position by means of adapted clamps 3, thus forming a cavity that corresponds to the fuselage of the ultralight aircraft.
• Figure 2 is a sectional view of the two half-molds 1 and 2, closed together and kept in position by the two clamps 3. The further details of figure 2 and of figures 3 and 4 will be described later.
• Figure 5 is a view of a multipart mold for forming the wings of the aircraft; the mold is formed by an upper half- mold 21 and by a lower half-mold 20 that are closed to each other and kept together, as shown in the sectional view of figure 6, by appropriate clamps 3, like the two half-molds 1 and 2 used to form the fuselage 100.
• Figures 6 and 7 are, respectively, a sectional view of the mold for forming the wings and a sectional view of a constructive detail of a wing; they will be described hereinafter together with the explanation of the method for manufacturing the ultralight aircraft according to the invention.
• Figure 10 is a view of the components constituting the interiors of the aircraft according to the invention. More particularly, the components are executed with a single mold, in successive steps, forming an inner shell, and are then assembled to the fuselage 100 formed by means of the two half-molds 1 and 2.
• the reference numeral 210 designates the component that constitutes the bottom, to be arranged in a downward region inside the fuselage 100; 220 and 230 designate respectively the right and left lateral internal frames; 240 designates the support for the seats 250; 260 designates the instrument panel; 270 designates the control tunnel; and the reference numeral 280 designates the component that constitutes the upper portion of the interiors of the ultralight aircraft according to the invention.
• the method for manufacturing the aircraft according to the invention is as follows.
• portions of structural fiber 4 such as for example glass, carbon, kevlar, boron or others impregnated with polymerizable resin and appropriately shaped, are placed inside the two half-molds 1 and 2; sheets of cellular material of the honeycomb type 5, and another layer of structural fiber 6, also impregnated with polymerizable resin, are arranged on these portions of fiber 4; a layer of structural adhesive film 10, advantageously formed by resins, usually epoxy resins, is interposed between the layer 4 and the sheets 5 and between the sheets 5 and the layer 6 respectively.
• structural adhesive film 10 advantageously formed by resins, usually epoxy resins
• a plastic layer 7 is applied on the plurality of layers described above and acts as a vacuum bag; said layer is sealed and subjected to suction in order to compact the layer 4, the sheets 5, and the layer 6 together.
• the polymerizable resin with which the structural fiber fabric 4 is impregnated is preferably constituted by a thermosetting resin chosen in the group comprising phenolic resins, urea-formaldehyde, melamine-formaldehyde, and amine resins in general, alkyl resins, and polyester, epoxy resins, and polyurethanes.
• thermoplastic resins provided that they have a softening point that is higher than the operating temperature of the composite component to be produced.
• the sheets 5 may be omitted and the layers 4 and 6 thus coincide, forming a monolithic structure made only of resin reinforced with structural fibers.
• the layers 5 can be constituted by a hexagonal cellular structure of the honeycomb type or by a resin, for example a polyester or polyurethane resin, optionally treated to make it fireproof or self-extinguishing.
• a resin for example a polyester or polyurethane resin, optionally treated to make it fireproof or self-extinguishing.
• the mold is opened and the monolithic fuselage 100 is removed from the shell, finished, and sent to the assembly operations.
• inserts 8 made of metal, plastics or other material are also embedded in the various layers in the desired positions, so as to rigidly couple them to the structure formed in the mold. These inserts 8 allow to obtain a fuselage 100 that is provided with all the devices for the passage of the cables for actuating the ailerons, the rudders, and all the other devices required to steer the ultralight aircraft, without requiring assembly by riveting or any other conventionally used method. This leads to a considerable saving in time and therefore to a containment of production costs.
• the inserts are placed at the points for coupling to the other parts of the aircraft
• Inserts 8 made of metal, plastics, or other adapted material, or reinforcements obtained with additional layers of material impregnated with polymerizable resin, are arranged in the section of the fuselage 100 at the cabin compartment, so as to obtain a non-deformable rigid structure that surrounds the housing of the seats 250 and is capable of cushioning any impacts that might occur in case of emergency conditions.
• the rigidity of the region corresponding to the cabin compartment is provided by the assembly of the components that constitute the monolithically formed interiors of the aircraft to the fuselage 100.
• the assembly is advantageously provided for example by gluing or mechanical fixing.
• the structure obtained from the assembly of the fuselage and of the monolithically-executed interiors gives the structure of the aircraft a particular rigidity, forming a so-called "safety c ige" at the cabin.
• the wings 101 and 102 and the rudders can be formed monolithically by using the same production method used for the fuselage 100 and for the interiors of the aircraft.
• layers of fabric made of structural fiber 22, impregnated with polymerizable resin and shaped appropriately, are arranged in an upper half-mold 20 and in a lower half-mold 21 that are shaped appropriately.
• a sheet of cellular material 23 is applied on said layers 22, and a further layer of impregnated fabric 24 is placed on the sheet.
• the plurality of layers described above is enclosed in a vacuum bag 25.
• the half-molds 20 and 21 are kept closed together by appropriate retention devices 3 and are held at an appropriate temperature and under pressure, for example in an autoclave, for the time required for polymerization. More particularly, the sheet of cellular material 23 may be omitted and therefore the layers 23 and 24 may coincide.
• figure 7 illustrates the embedding of an insert 30, for assembling the wings to the fuselage, inside the cavity formed by the two half-molds 20 and 21 in contact with the layer of cellular material 23.
• the inserts are appropriately coated with polymerizable structural adhesives to ensure perfect airworthiness.
• Two reinforcement elements for example two spars 50 and 60 having a double-T cross-section, are then inserted in each wing 101 and 102 to provide rigidity to the entire structure .
• the execution of the rudder 103, of the ailerons 108- 109 and of the tail planes 104-105 follows the same production method as the wings 101-102.
• the operations for assembling the entire ultralight aircraft are thus reduced to connecting a fuselage 100 to the two wings 101 and 102, the tail planes 104 and 105, the rudder 103, the trim tabs 106 and 107, the ailerons 108, 109, and an undercarriage 110.
• the wings can be designed so as to rotate along the fuselage to allow easier transport of the aircraft, for example by means of a trailer.
• the ultralight aircraft according to the invention fully achieves the intended aim and objects, since it is constructed monolithically without riveting operations. Said structure is particularly strong and easily assembled.
• the assembly of two shells, an outer shell constituting the fuselage 100 and an inner shell constituting the interiors of the fuselage allows to obtain a rigid structure that ensures a high safety standard particularly at the crew compartment.
• the ultralight aircraft according to the invention is made of advanced composite materials capable of giving the structure high rigidity and nondeformability as well as a high rigidity /weight ratio.
• the monocoque ultralight aircraft thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.
• the wings 101 and 102 of the ultralight aircraft according to the invention can be built so that the spar 50 having a double-T transverse cross- section, shown in figure 9 and provided in each wing at the portion having the greatest camber, has such a length as to protrude from the end of each wing that is directed towards the fuselage 100, so as to allow the connection, for example by bolting, of the ends of the two spars inside said fuselage, thus allowing the connection of the wings 101 and 102 to each other as well as to the fuselage 100.
• This type of connection ensures high rigidity of the wing assembly, so that it is possible to eliminate the external tie rods 200 that are provided on the left and right sides of the aircraft and connect the lower portion of the fuselage 100 to the wings 101 and 102 respectively.
• the polymerization of the layers impregnated with resin can be performed not only when the molds are assembled but also when they are disassembled. More particularly, polymerization can be performed in subsequent steps, and different parts of the fuselage 100 can be made to polymerize at different times and with different methods.
• the materials employed may be any according to the requirements and the state of the art.

Landscapes

• Engineering & Computer Science (AREA)
• Aviation & Aerospace Engineering (AREA)
• Mechanical Engineering (AREA)
• Moulding By Coating Moulds (AREA)
• Automatic Assembly (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11373155

Family Applications (1)

Country Status (3)

Citations (4)

• 1996
  • 1996-02-06 IT IT96MI000213A patent/IT1282005B1/it active IP Right Grant
• 1997
  • 1997-01-31 WO PCT/EP1997/000425 patent/WO1997029013A1/en active Application Filing
  • 1997-01-31 AU AU15981/97A patent/AU1598197A/en not_active Abandoned

Patent Citations (4)

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