Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C21/00—Influencing air flow over aircraft surfaces by affecting boundary layer flow
  • B64C21/02—Influencing air flow over aircraft surfaces by affecting boundary layer flow by use of slot, ducts, porous areas or the like
  • B64C21/025—Influencing air flow over aircraft surfaces by affecting boundary layer flow by use of slot, ducts, porous areas or the like for simultaneous blowing and sucking
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C2230/00—Boundary layer controls
  • B64C2230/04—Boundary layer controls by actively generating fluid flow
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C2230/00—Boundary layer controls
  • B64C2230/22—Boundary layer controls by using a surface having multiple apertures of relatively small openings other than slots
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D33/00—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
  • B64D33/02—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes
  • B64D2033/0226—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes comprising boundary layer control means
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/10—Drag reduction

Definitions

• the present invention relates to boundary layer control and is particularly although not exclusively concerned with the control of the laminar flow of air in a boundary layer adjacent a face of a component of an aircraft exposed to high speed air flow during flight.
• boundary layer control It has hitherto been proposed for boundary layer control to drill a multitude of small holes in the skin of the component and to provide a ducting system connecting the skin to a vacuum or low pressure source.
• a plenum chamber is provided beneath the skin to provide a uniform distribution of low pressure to the holes provided in the skin.
• a low drag component responsive to movement relative to a surrounding gaseous medium to produce at a front face of the component laminar flow in a boundary layer adjacent the front face, the component including a cellular face region which includes the front face and which has an open- celled structure which permits gaseous fluid flow through the front face and between the front face and a rear face of the face region, and gaseous fluid conveying means at the rear of the face region to permit or cause gaseous fluid flow from or to the boundary layer to control laminar flow in the boundary layer.
• open-celled structure is meant a cellular structure having a multiplicity of intercommunicating cells obtained by aggregation of particulate material or by the displacement of material by a dispersion or like technique from a body of material in liquid phase followed by a solidifying step.
• the face region is made from a porous permeable thermoplastics material.
• the face region is produced by powder sintering the thermoplastics material.
• the face region is made from a porous permeable composite material formed from a thermoplastics matrix material reinforced with one or more non- thermoplastic reinforcing materials.
• the face region is produced by powder sintering the composite material.
• the face region is in the form of a facing component part
• the component further comprises a base component part having a front face adjoining the rear face of the facing component part
• the gaseous fluid conveying means comprises channel means at the interface of the facing component part and the base component part.
• the channel means provides for gaseous fluid flow through the rear face of the facing component part at predetermined locations over a selected area of the facing component part.
• the locations may be discrete locations over the selected area.
• the facing component part may then be so manufactured that the density of the open-celled structure varies over the selected area, producing a maximum resistance to gaseous fluid flow at each of the discrete locations and a minimum resistance to gaseous fluid flow between the locations to provide for a uniform or substantially uniform flow rate through the face of the facing component part over the selected area.
• the variation in the open-celled structure is preferably obtained during powder sintering of the thermoplastics or composite material.
• thermoplastics or composite material is presented as a sheet for powder sintering with the thickness of the sheet being increased in zones to be aligned with the discrete locations over the selected area whereby powder sintering of the sheet produces a more densely packed open-celled structure in these zones, offering higher flow resistance than between the zones.
• the thickness in the zones may be increased by the superposition of a succession of additional layers of material of successively reducing size.
• the channel means take the form of a plurality of channels which are formed in the rear face of the facing component part and which serve as passageways for the gaseous fluid.
• Each channel has impermeable walls except at the discrete locations at which the wall is permeable to permit flow of gaseous fluid into or from the channel.
• the channel means take the form of a plurality of channels which are formed in the front face of the base component part and which serve as passageways for the gaseous fluid.
• the channels provided in the rear face of the facing component part or in the front face of the base component part may be arranged in spaced parallel relation across the width or along the length of the component and may be so dimensioned as additionally to serve as plenum chambers .
• the component further comprises one or more manifold elements which extend across a rear face of the base component part in a direction transverse to the parallel channels and openings are provided in the base of each channel for flow communication between the channel and the manifold.
• the manifold or each manifold may take the form of a top hat stiffening element which is bonded to the rear face of the base component part to impart structural rigidity to the component as well as serving as a manifold.
• the base component part is formed with a recess
• the channels are formed in the base of the recess and the facing component part fits within the recess between shoulders of the base component part formed by the recess.
• the face region is in the form of a facing component part
• the component further comprises a base component part having a front face adjoining the rear face of the facing component part
• the gaseous fluid conveying means includes a plenum chamber in the front face of the base component part and the chamber so extends over the rear face of the facing component part as to provide a uniform fluid flow inducing pressure over a selected area of the facing component part.
• the facing component part may then have a cellular structure which is of uniform density over the selected area so as to provide for uniform gaseous fluid flow through the front face of the facing component part.
• the base component part has a cellular structure formed by wall portions which extend across the base component part from the front face to the rear face and which provide bounding surfaces for an array of juxtaposed cells which terminate in open ends at the front face.
• the gaseous fluid conveying means takes the form of openings in the wall portions to provide flow communication between adjacent cells and manifold means are provided in flow communication with the cells of the base component part.
• the front face of the facing component part may advantageously be ribbed to improve laminar flow in the boundary layer.
• an aircraft including a low drag component according to the first aspect of the invention.
• a boundary layer control arrangement comprising a low drag component according to the first aspect of the invention and suction means communicating with the conveying means to cause gaseous flow from the boundary layer through the front face, through the face region of the component from the front face to the rear face and through the conveying means.
• an aircraft including a boundary layer control system according to the third aspect of the invention.
• a method of controlling laminar flow in a boundary layer adjacent the front face of a component according to the first aspect of the invention comprising the step of applying suction to the fluid conveying means to cause gaseous fluid to be withdrawn from the boundary layer through the front face of the component and through the face region of the component between the front face and a rear face of the component and the conveying means.
• Fig 1A is a schematic isometric view of a part of an aircraft wing showing the location of a component according to the invention
• Fig IB is a view corresponding to that shown in Fig 1A of part of an aircraft wing showing a component according to the invention in a form different from that shown in Fig
• Fig 2A is a schematic isometric view from below of a facing component part of a component according to an embodiment of the invention, in which air flow channels are formed in the rear face of the component part
• Fig 2B is a schematic section, taken on the line II-II in Fig 2A, of a part of the facing component part shown in Fig 2A with a base component part for supporting it
• Fig 3A is a schematic representation of a processing step in the formation of a facing component part of a component according to the invention, in which material in sheet form and of variable thickness is powder sintered to produce a constant thickness component part of variable density
• Fig 3B is an enlarged schematic view of a portion of the sheet to be sintered and as shown in Fig 3A
• Fig 3C is a schematic cross-section of the built up sheet shown in Fig 3B, prior to powder sintering
• Fig 3D is a schematic cross-section of the sheet shown in Fig 3A after powder sintering
• Fig 3E is a graph of the vacuum experienced at the face of a component according to the invention where the sheet forming the facing component part is of uniform density
• Fig 3F is a graph of the flow rate of air through a facing component part according to the invention where the component is made from a powder sintered sheet in the manner illustrated in Figs 3A to 3D
• Fig 4A is a schematic isometric view from below of a facing component part of a component according to a further embodiment of the invention, in which air flow channels are formed in the rear face of the facing component part in a configuration different from that shown in Fig 2A
• Fig 4B is a schematic section of the facing component part shown in Fig 4A, taken on the line IV-IV in Fig 4A, together with a base component part by which the facing component part is supported
• Fig 5A is a schematic isometric part view of a component according to a still further embodiment of the invention, in which air flow channels are formed in the front face a base component part of a component according to the invention
• Fig 5B is a schematic section of the component shown in Fig 5A taken on the line V-V in Fig 5A
• Fig 5C is a schematic perspective view of an aircraft wing, illustrating a location for the component shown in Figs 5A and 5B
• Fig 6 is a schematic isometric view of a part of a base component part of a component according to another embodiment of the invention, formed with channels extending transverse .to the channels in the base component part shown in Figs 5A and 5B
• Fig 7A is a schematic isometric view partly cut away and viewed from above of a component according to a yet another embodiment of the invention
• Fig 7B is a sectional scrap view of the component shown in Fig 7A, taken on the line VII-VII in Fig 7A
• Fig 7C is a schematic perspective view of an aircraft wing, illustrating a location for the component shown in Figs 7A and 7B
• Fig 8A is a schematic isometric view partly cut away of a component according to a further embodiment of the invention
• Fig 8B is a schematic section of the component shown in Fig 8A taken on the line VIII-VIII in Fig 8A
• Fig 9A is a schematic isometric view of a component according to yet another embodiment of the invention.
• Fig 9B is a schematic part sectional end view of the component illustrated in Fig 9A
• an aircraft wing section 11 which includes at its upper leading edge a component 12 made in accordance with the invention.
• the component 12 is connected to a suction source (not shown) via conveying means hereinafter to be described for applying suction to the component 12 to withdraw air from the boundary layer adjacent the upper surface of the wing at the leading edge to control flow in the boundary layer, with the aim either of maintaining laminar flow throughout the chordwise extent of the upper surface of the wing section 11 or of shifting the boundary layer transition point on the upper surface downstream as far as possible.
• the component 12 takes the form of a sheet of uniform thickness which extends spanwise and fits into a recessed part of the wing structure.
• the wing section 11 embodies a component 12 1 which extends completely over the upper leading edge of the wing section 11.
• the component 12 1 is feathered at its leading and trailing edges and would normally be used for boundary layer control only and not serve as an effective structural part of the wing section.
• a low drag component 12 according to the invention comprises a facing component ⁇ art 13 and a base c ⁇ ⁇ onent oart 14.
• the facing component part 13 is produced as hereinafter to be described with reference to Figs 3A to 3F by powder sintering of a thermoplastics material in particulate form optionally reinforced with one or more non- thermoplastics reinforcing materials to produce a porous permeable thermoplastics sheet of uniform thickness.
• the facing component part 13 has a front face 15 and a rear face 16 and is produced as shown with channels 17 formed in the rear face 16.
• each channel 17 is of semi ⁇ circular cross section with bounding walls 18 which are impermeable except at discrete openings 19 where localised areas of the upper wall are permeable.
• the formation of the channels 17 is preferably made during the production of the part 13 in the powder sintering process, although if desired they may be formed subsequently.
• the facing component part 13 is bonded at its rear face 16 by an adhesive 20 to the base component part 14 , which is of a non-porous impermeable material and which serves to provide structural strength for the component 12 and to close off the channels 17.
• the channels 17 terminate at closed ends 21 and are connected at their open ends to a suction source not shown.
• suction is applied to the channels 17 to produce a low pressure at the discrete openings 19 where the channel walls are permeable with the result that air is drawn through the front face 15 of the facing component part 13 and through the component part 13 between the front face 15 and rear face 16 into the channels 17 for discharge at a discharge point at the suction source.
• the component 12 as described with reference to Figs 2A and 2B is mounted as shown in Fig 1A in the upper leading edge of the wing section 11 and the withdrawal of air through the front face 15 serves to maintain laminar flow in the boundary layer during flight of the aircraft as hereinbefore described.
• the density of the facing component part 13 can be varied so as to offer increased resistance to flow at each discrete opening 19, reducing to a minimum resistance to flow in the region between the opening 19.
• a layer 22 of a thermoplastics material in particulate form is shown supported by a conveyor 23 which is arranged to be advanced through the nip of a pair of heated rollers 24 and 25.
• the rollers 24 and 25 are preset to provide a gap 26 which will cause the layer 22 when advanced on the conveyor 23 through the rollers 24 and 25 to be compacted to the required particulate packing density to produce a powder sintered sheer at the outlet side of the rollers 24 and 25.
• the layer 22 of particulate material has superposed on it at spaced locations 30 circular localised further layers 27, 28 and 29 of thermoplastics material of circular form with progressively reducing diameters, thereby to provide at these spaced locations 30 a build up of particulate material with a maximum thickness at the centre of each location 30.
• the layer 22 is advanced through the rollers 24 and 25 which cause the material to be sintered with the regions at the locations 30 being compressed to a higher packing density than the regions between them ro produce as illustrated in Fig 3D a constant thickness porous permeable thermoplastics sheet 31 having a variable particulate packing density with maximum density at the locations 30.
• Fig 3E is plotted a curve which illustrates the surface vacuum variation resulting from connection of the localised openings 19 to a vacuum source, while Fig 3F illustrates the uniform flow rate through the face 34 of the sheet 31 by virtue of the increased packing density at the locations 30.
• the facing component part 13 described with reference to Figs 2A and 2B is preferably produced in a single processing step to provide in addition to the channels 17 and openings 19, increased density at locations 30 aligned with the openings 19 in the channels 17 so as to achieve a uniform or substantially uniform flow rate over the face 15 of the facing component part 13.
• the facing component part 13 takes the same form as that described with reference to Figs 2A and 2B and is produced in the same manner as that described with reference to Figs 3A to 3F, except insofar that the channels 17 are replaced by an arterial channel 34 extending for the full length of the part 13 with branch channels 35 leading to radial channels 36 which terminate in closed enlarged ends 37.
• the channels 34, 35 and 36 have impermeable walls and the enlarged ends 37 are left in part permeable to provide openings 19 corresponding to the openings 19 in the channels 17 of the facing component part 13 described with reference to Figs 2A and 2B.
• the packing density of the facing component part 13 is varied over the area of the facing component part 13 in the same manner as that described with reference to Figs 3A to 3F with the maximum packing density and therefore maximum resistance to flow being provided over the openings 19 and the minimum packing density and lower resistance to flow being provided in the regions between the openings 19.
• the facing component part 13 is bonded to the base component part 14 to close off the channels 34 to 36 and the enlarged ends 37.
• the arterial channel 34 is open at its ends for connection to a suction source (not shown) via appropriate manifolds.
• the component 12 is formed from a facing component part 13 and a base component part 14.
• the facing component part 13 is of uniform thickness and is produced by powder sintering particulate thermoplastics material to a packing density which is uniform throughout.
• the base component part 14 which is of non- porous impermeable material is formed with a recess 38, the base of which is formed with a plurality of channels
• the facing component part 13 fits, as shown, into the recess 38 so as to be flush with the surfaces 43 and 44 of the shoulders 45 and 46 which flank the recess 38.
• the channels 39 are of substantial depth so as to serve as plenum chambers to provide for a uniform distribution of low pressure throughout each channel.
• the component 12 illustrated in Figs 5A and 5B may with advantage be used for boundary layer control in the upper surface of a wing section as illustrated in Fig 5C.
• suction is applied by the suction source to the manifold 41 and via the openings 40 to the channels 39 causing air to be withdrawn from the boundary layer adjacent the upper surface of the wing section 11, through the face 15 and the body of the facing component part 13 to effect boundary layer control as hereinbefore discussed.
• the component 12 comprises a facing component part 13 of the same form and produced in the same manner as the facing component part 13 in Figs 5A and 5B and a base component part 141 of non-porous impermeable material formed with a recess 38 corresponding to that shown in Fig 5A, the base of which is however formed with an array of channels 39 1 which extend in spaced parallel relation in a direction at right angles to that of the channels 39 in the embodiment described with reference to Figs 5A and 5B.
• a manifold 41 is in like manner bonded to the rear face of the base component part 14 and communicates with the channels 39 1 via openings 40 formed in the base of the channels.
• the component 12 which has been formed using the facing component part 13 as described with reference to Fig 5A and the base component part 14 1 as described with reference to Fig 6 may alternatively be used for boundary layer control at the upper surface of the wing section 11 as in the position illustrated in Fig 5C.
• the component 12, shown inverted in Fig 7A comprises a facing component part 13 provided with channels 17 1 formed in the rear face 16 in the same manner as the channels 17 of the component part
• the base component part 14 is of uniform thickness and made from a non-porous impermeable material and is bonded to the rear face 16 of the facing component part 13. To the rear face 42 of the base component part
• the channels 17 1 are closed at each end and formed in the rear face of facing component part 13 in such a way as to leave them with permeable walls throughout.
• the component 12 as illustrated in Figs 7A and 7B is suitable for embodying within the surface of a wing section 11 in the manner illustrated in Fig 1A or at other positions in an aerodynamic surface of the aircraft, such as for example at the lower leading edge surface of the wing section 11 as illustrated in Fig 7C.
• channel 17 1 in the embodiment of the invention described with reference to Figs 7A and 7B may be formed with impermeable walls except at discrete locations where they are permeable and form openings 19 and the packing density of the material forming the facing component part 13 may then be arranged to vary over the area of the face 15 to provide for a uniform flow of air through the face 15 as in the embodiment of the invention described with reference to Figs 2A and 2B and 3A to 3F.
• the component 12 comprises a facing component part 13 of uniform thickness secured to a base component part 14 of non-porous impermeable material and has a recess 48 within bounding walls 49.
• the recess 48 extends substantially throughout the surface area of the component 12 and it is formed with an opening 49 for connection to a suction source.
• the facing component part 13 is secured to the walls 49 of the base component part 14 by headed screws 50 which pass through countersunk holes in the facing component part 13 and are screwed into threaded holes provided in the walls 49.
• the recess 48 serves as a plenum chamber to provide an even distribution of low pressure throughout the effective area of the facing component part 13.
• the facing component part 13 is unsupported over the recess 48 and is reinforced preferably with a non-thermoplastic reinforcing material combined with the thermoplastic material or by providing an external perforated open weave carbon fibre fabric sheet bonded to it.
• the base component part 14 is formed as a solid structure reinforced in some embodiments by manifolds.
• the base component part 14 In order to provide a lightweight structure of sufficient strength for use as a component in an aircraft surface structure it may be appropriate to make the base component part 14 of a cellular structure and with this in mind there is shown in Figs 9A and 9B a component 12 having a base portion 14 of this form.
• the facing component part 13 is in the form of a sheet of uniform thickness. It is produced by the sintering process described with reference to Figs 3A to 3F but simplified to have a uniform packing density throughout.
• the base component part 14 on the other hand comprises a cellular core 141 having wall portions 142 which provide bounding surfaces for an array of cells 143 which in the embodiment illustrated are of hexagonal cross section and form what is termed a "honeycomb core".
• Each of the cells 143 of the cellular core 141 are in communication with each other through openings 144 formed in the walls of the cells and the component is completed by enclosing the cellular core within an enclosing cover 145 which is provided with an outlet duct 51 for connection to a suction source.
• the component 12 of the embodiment illustrated in Figs 9A and 9B may be mounted in an appropriate position in an aircraft surface structure to provide boundary layer control over the surface in the same manner as that proposed for the embodiments of the invention hereinbefore described, with suction being applied to the suction duct 51 to withdraw air from the boundary layer through the front face 15 of the facing component part 13 through the cells 143 and the openings 144 to the duct 51 and through the duct 51 to a discharge point at the suction source.
• the face 15 of the facing component part 13 may be ribbed to improve laminar flow across it.
• Such ribbed configuration may be formed at the time the facing component part 13 is produced in the powder sintering process or the face 15 machined after production of the part 13.
• the facing component point 13 is preferably made by powder sintering a thermoplastic material in particulate form.
• suitable thermoplastics material for the facing component part 13 include polyether ketone, polyether ether ketone, polyaromatic ketone, polyphenylene sulphide, polyamide-imide and thermoplastic polyimide, polyether-imide, polyurethane and polyethylene.
• the base component part 14 requires to be non-porous and impermeable and may be made of any of the following material:-
• thermoplastic is polyether ether ketone
• the cellular core 141 is preferably made from a non- porous impermeable sheet of any of the following materials:-
• thermoplastic such as polyether ether ketone.
• NOMEX being a registered trade mark for an aramid fibre paper impregnated with various resins to produce a structural material.
• aramid is meant an aromatic polyamide polymer.
• the cellular core 141 of the base component part 14 of the embodiment described with reference to Figs 8A and 8B may, if desired, be in the form of an open-celled plastics foam which may be manufactured from any suitable thermoplastics material.
• suitable thermoplastics materials include polyether ketone, polyether ether ketone, polyaromatic ketone, polyphenylene sulphide, polyamide-imide, thermoplastic polyimide, polyether-imide, polyurethane and polyethylene. It may for example be formed from the same thermoplastics material as that from which the facing component part 13 is formed.
• the facing component part 13 in all the embodiments of the invention hereinbefore to be described is made from a porous and permeable thermoplastics material. It may however be combined with a non-thermoplastics material to form a composite material which is then subjected to sintering.
• the reinforcing material combined with the thermoplastic material may be in any of the following forms:-
• the reinforcing material may be added in various quantities to impart (i) strength, (ii) stiffness (iii) to reduce the net coefficient of thermal expansion or (iv) to vary the flow resistance properties of the material.
• Boundary layer control using a component according to the invention possesses the following material/structural characteristics: -
• porous permeable thermoplastic facing component part 13 is readily produced by a sintering process.
• the porosity of the material forming the facing component part 13 may be varied over a given area by control over the sintering process, when required.
• the material of the facing component part 13 may be made impermeable by over compacting (ie particles completely fused together) , when required.
• the material forming the facing component part 13 may be shaped during the sintering process.
• thermoplastics material may be combined with high performance fibres (carbon, kevlar, glass, boron etc) to produce a lightweight structural component.
• the fibres may be continuous, chopped or woven.
• a range of fillers may also be incorporated at the sintering stage to improve stiffness and vary flow characteristics
• Figs 1A and IB illustrate possible locations of the component on a typical aerofoil section.
• the size and location of component 12 may readily be determined by experimentation and from the function of the underlying structure. Many conventional applications (ie wing surface, control surfaces, nacelles and the like) would however require redesigning.
• porous permeable thermoplastic facing component part 13 may be configured with more conventional composite and metallic materials in order to increase load bearing capabilities.
• the design of the stiffening elements may be so configured that they act in a secondary role as air duct systems, hence reducing the complexity of the sintering process (ie a relatively flat porous component part 13 with uniform flow capacity may suffice) .
• Figs 5A and 5B illustrate a variation in that a plenum chamber is incorporated, allowing a thermoplastic outer facing component part 13 with uniform density to be utilized, significantly simplifying the sintering process.
• the basic differences between this arrangement and that of the prior proposal is the use of a porous permeable thermoplastics material in place of drilled holes.
• the plenum chamber may be machined or fabricated from alloy or alternatively moulded in conventional reinforced thermoset or thermoplastic materials.
• the manifolds in the form of tophat stiffening elements may be bonded to the plenum bottom surface to impart structural rigidity as well as serving as a manifold, directing air to the vacuum source.
• Figure 6 illustrates a further structure, again incorporating plenum type chambers.
• the direction of these chambers and the underlying manifolds have been interchanged. This may be necessary in order to align with the surrounding structures load paths.
• plenum chamber effect has been incorporated into the porous thermoplastic facing component part 13 by the use of channels 17 1 .
• These channels or chambers may be machined after sintering or formed during sintering by dedicated tooling.
• the sintered skin is bonded to a carbon fibre composite or light alloy base component part 14 predrilled to permit air transfer to co-cured or bonded tophat manifolds 43 and 44.
• These manifolds serve as stiffeners as well as being an integral part of the vacuum source network.
• thermoplastic facing component part 13 mechanically fastened to an underlying base component part 14 shaped to produce a plenum chamber when assembled.
• the most significant aspect of the design is the structural nature of the thermoplastic facing component part 13, replacing the role of the tophat manifold stiffeners.
• the reinforcement may be incorporated at the sintering stage (ie continuous fibre, discontinuous long fibre, chopped fibre or filler powders) .
• the part 13 may be stiffened by secondary bonding with for example, perforated mesh, open weave carbon fibre or drilled laminates, to form a sandwich arrangement.
• porous thermoplastic facing component part 13 is combined with a honeycomb core 141 and backing skin 145 of light alloy or advanced composite to form a sandwich structure capable of flowing air whilst resisting structural loads.
• the backing skin 145 must be sealed to the porous facing component part 13 at the periphery in order to maintain vacuum integrity.
• the individual honeycomb cells 143 are interconnected by openings 144 to allow lateral airflow.
• the porous permeable thermoplastic facing component part 13 may be combined with high performance fibres (carbon, kevlar, glass, boron etc) . Integrated designs can reduce the requirement for ducting and additional stiffening of the underlying structure and it is anticipated that little additional weight would be incurred by implementing such designs.
• thermoplastics material may be coloured during the sintering process producing a material which requires no touch up work after drilling, cutting or the like.

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• Engineering & Computer Science (AREA)
• Aviation & Aerospace Engineering (AREA)
• Liquid Crystal (AREA)
• Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
• Farming Of Fish And Shellfish (AREA)

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• 1991
  • 1991-05-30 GB GB919111620A patent/GB9111620D0/en active Pending
• 1992
  • 1992-05-27 EP EP92910640A patent/EP0585305A1/en not_active Withdrawn
  • 1992-05-27 CA CA002106850A patent/CA2106850A1/en not_active Abandoned
  • 1992-05-27 GB GB9211225A patent/GB2256253B/en not_active Expired - Fee Related
  • 1992-05-27 AU AU17672/92A patent/AU1767292A/en not_active Abandoned
  • 1992-05-27 WO PCT/GB1992/000956 patent/WO1992021560A1/en not_active Application Discontinuation
  • 1992-05-29 IL IL102048A patent/IL102048A0/xx unknown

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