WO1988004479A1 - Process and device for camouflaging power unit inlets - Google Patents

Process and device for camouflaging power unit inlets Download PDF

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Publication number
WO1988004479A1
WO1988004479A1 PCT/EP1987/000745 EP8700745W WO8804479A1 WO 1988004479 A1 WO1988004479 A1 WO 1988004479A1 EP 8700745 W EP8700745 W EP 8700745W WO 8804479 A1 WO8804479 A1 WO 8804479A1
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WO
WIPO (PCT)
Prior art keywords
waveguide
radar
channels
aircraft
section
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Application number
PCT/EP1987/000745
Other languages
German (de)
French (fr)
Inventor
Alois Knopf
Reinhard Popp
George Wilhelm Stroke
Original Assignee
Messerschmitt-Bölkow-Blohm Gesellschaft Mit Beschr
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Application filed by Messerschmitt-Bölkow-Blohm Gesellschaft Mit Beschr filed Critical Messerschmitt-Bölkow-Blohm Gesellschaft Mit Beschr
Publication of WO1988004479A1 publication Critical patent/WO1988004479A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS 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
    • B64D2033/0253—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of aircraft
    • B64D2033/026—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of aircraft for supersonic or hypersonic aircraft
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS 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
    • B64D2033/0266—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of power plants
    • B64D2033/0286—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of power plants for turbofan engines

Definitions

  • the invention relates to a method for radar camouflaging engine inlets in aircraft, such as those represented by aircraft and missiles, and devices for carrying them out.
  • Engine inlets are particularly critical in this regard because the electromagnetic waves can penetrate into the interior of the engine inlet, where they are reflected several times and scattered widely. As a result, they appear as eye-catching reflectors from every angle.
  • this is achieved in that, in order to reduce the global radar cross-section of the entire aircraft, the openings of the engine inlets are divided into several cells or channels with smaller openings by radar-reflecting, air-permeable structures, which, on the one hand, do not dimension the incident electromagnetic waves due to their dimensioning allow the inside of the engine inlet to penetrate, but instead reflect as if at a conductive level and, on the other hand, provide the lowest possible frictional resistance to the air flow.
  • FIG. 1 shows a longitudinal section of an engine inlet pipe with a radar-reflecting but air-permeable lattice structure at the inlet opening
  • FIG. 6 shows a waveguide structure with a hexagonal honeycomb cross-section
  • FIG. 7 shows a longitudinal section of an engine inlet pipe with a waveguide structure of different length of the elements
  • FIG. 8 shows a longitudinal section of an engine inlet pipe with a waveguide structure with funnels at both ends of the elements
  • 9 shows a variant of the object of FIG. 8 with baffles in the funnel opening of the elements
  • FIG. 10 shows a longitudinal section through an element of the waveguide structure according to FIG. 9 with guide plates in the funnel opening
  • FIGS. 10 and 11 shows a cross section through the opening of the funnel according to FIGS. 10 and
  • Fig. 12 is a longitudinal section of an oblique engine inlet pipe with a corresponding waveguide structure.
  • FIG. 1 shows a longitudinal section of an engine inlet pipe with a radar-reflecting but air-permeable lattice structure at the inlet opening;
  • Figure 2 shows the cross section through the subject of Figure 1 and
  • Fig. 3 schematically shows a square mesh structure.
  • the radar of the engine inlet 1 To camouflage the radar of the engine inlet 1, according to the invention, its opening is divided into many cells or channels with a smaller opening by a specifically radar-reflecting, air-permeable structure 2, which on the one hand, due to their dimensioning, do not allow the incident electromagnetic waves to penetrate into the interior of the engine inlet, but rather how Reflect specifically on a conductive plane and on the other hand oppose the lowest possible frictional resistance to the air flow.
  • the structure 2 consists of a mesh grating 3 which, due to the appropriate dimensioning of the mesh size d (d ⁇ MIN / 2 with ⁇ MIN as the smallest wavelength to be reflected) acts as a high pass for the incident electromagnetic waves and therefore reflects waves below its cutoff frequency.
  • this structure can be further improved in that it is built up from a plurality of mesh gratings 4 which follow one another at a certain distance and which form a high-pass filter of a corresponding higher order for the electromagnetic wave and therefore have better reflective properties than a simple mesh.
  • the structure consists of square waveguide channels with a hollow! pus width d ⁇ MIN / 2 and a waveguide length 1> ⁇ MIN .
  • An improvement in aerodynamic properties can be achieved in that the structure according to FIG. 6 consists of waveguide channels with the cross section of a regular honeycomb hexagon with the waveguide width d ⁇ MIN / 2 and the hollow conductor length 1> ⁇ MIN .
  • the reflection can be controlled in certain directions, for example away from the location of the detectors, in that, according to FIG. 7, the lengths of the individual waveguide channels are different for the purpose of controlling the reflection in certain directions.
  • the waveguide channel can have a funnel opening at the front and / or rear as in the case of a horn antenna.
  • FIG. 10 shows a longitudinal section through an element of the waveguide structure with baffles in the funnel opening and
  • FIG. 11 shows a cross section through the opening of the funnel according to FIG. 10.
  • the structure according to the invention can also be used with inclined inlet connections.
  • the edges of the structure are expediently razor-sharp.
  • the described method and the devices shown appear more effective than absorption measures within the engine inlet and are also easier to implement in practice, provided the change in aerodynamic properties is taken into account in the engine design.

Abstract

A process (2) for camouflaging the inlets (1) of power units of aircraft and the like against detection by radar is disclosed. To reduce the global radar cross-section of the aircraft as a whole, the openings of the power unit inlets (1) are subdivided by appropriate radar-reflecting, air-permeable structures into several cells (3) or channels with smaller openings, which on the one hand owing to their dimensions do not allow the incident electromagnetic waves to penetrate into the power unit inlet (1) but reflect them as on a conductive plane, and which on the other hand oppose a minimum friction drag to the air stream.

Description

Verfahren und Vorrichtung zur Radartarnung von Triebwerkseinläufen Method and device for radar camouflage of engine inlets
Die Erfindung betrifft ein Verfahren zur Radartarnung von Triebwerkseinläufen bei Fluggeräten, wie sie Flugzeuge und Flugkörper darstellen, und Vorrichtungen zu dessen Durchführung.The invention relates to a method for radar camouflaging engine inlets in aircraft, such as those represented by aircraft and missiles, and devices for carrying them out.
Moderne Fluggerätekonfigurationen bestehen - von den Triebwerkseinläufen einmal abgesehen - im Hinblick auf eine bessere Radartarnung aus einer Vielzahl nahezu ebener Oberflächenelemente mit gleichsam spiegelnden Eigenschaften. Ein großer Teil der Energie der einfallenden elektromagnetischen Wellen wird an diesen Oberflächen gezielt in bestimmte Richtungen reflektiert. Abgesehen von diesen Richtungen bleibt der Radarquerschnitt solcher Konfigurationen in einem großen Aspektwinkelbereich relativ niedrig. Sie sind daher für ein Radar immer nur kurzzeitig sichtbar und daher schwer detektierbar.Apart from the engine inlets, modern aircraft configurations consist of a large number of almost flat surface elements with, as it were, reflective properties with a view to better radar camouflage. A large part of the energy of the incident electromagnetic waves is specifically reflected on these surfaces in certain directions. Apart from these directions, the radar cross section of such configurations remains relatively low over a wide range of aspect angles. They are therefore only visible for a short time to a radar and are therefore difficult to detect.
Leider wird aufgrund von komplexen Aufbauten am Fluggerät, wie sie Triebwerkseinläufe darstellen, der Effekt der gezielten Reflexion wieder zunichte gemacht. Triebwerkseinläufe sind in dieser Hinsicht besonders kritisch, da die elektromagnetischen Wellen in das Innere des Triebwerksei nlaufs eindringen können, dort mehrfach reflektiert und breit gestreut werden. Dadurch wirken sie aus jedem Blickwinkel als besonders auffällige Reflektoren.Unfortunately, due to complex structures on the aircraft, such as engine inlets, the effect of targeted reflection is nullified. Engine inlets are particularly critical in this regard because the electromagnetic waves can penetrate into the interior of the engine inlet, where they are reflected several times and scattered widely. As a result, they appear as eye-catching reflectors from every angle.
Es ist das Ziel der Erfindung, ein Verfahren zur Radartarnung von Triebwerkseinläufen bei Fluggeräten anzugeben und Vorrichtungen zu dessen Durchführung zu schaffen, die den globalen Radarquerschnitt des gesamten Fluggerätes reduzieren und eine Verminderung der Entdeckbarkeit durch Radar in einem großen Aspektwinkelbereich ermöglichen, ohne die aerodynamischen Eigenschaften wesentlich zu beeinträchtigen. Gemäß der Erfindung wird dies dadurch erreicht, daß zur Reduzierung des globalen Radarquerschnitts des gesamten Fluggeräts die Öffnungen der Triebwerkseinläufe durch gezielt radarreflektierende, luftdurchlässige Strukturen in mehrere Zellen bzw. Kanäle mit kleineren Öffnungen unterteilt werden, welche einerseits aufgrund ihrer Dimensionierung die einfallenden elektromagnetischen Wellen nicht in das Innere des Triebwerkseinlaufs eindringen lassen, sondern wie an einer leitenden Ebene gezielt reflektieren und andererseits dem Luftstrom einen möglichst geringen Reibungswiderstand entgegensetzen.It is the object of the invention to provide a method for radar camouflaging engine inlets in aircraft and to provide devices for carrying them out which reduce the global radar cross section of the entire aircraft and enable a reduction in the detectability by radar in a wide aspect angle range, without the aerodynamic properties being essential to affect. According to the invention, this is achieved in that, in order to reduce the global radar cross-section of the entire aircraft, the openings of the engine inlets are divided into several cells or channels with smaller openings by radar-reflecting, air-permeable structures, which, on the one hand, do not dimension the incident electromagnetic waves due to their dimensioning allow the inside of the engine inlet to penetrate, but instead reflect as if at a conductive level and, on the other hand, provide the lowest possible frictional resistance to the air flow.
Einzelheiten der Erfindung ergeben sich aus den Unteransprüchen und der Beschreibung, in der anhand der Zeichnung mehrere Ausführungsbeispiele erörtert werden. Es zeigenDetails of the invention emerge from the subclaims and the description, in which several exemplary embodiments are discussed with reference to the drawing. Show it
Fig. 1 einen Längsschnitt eines Triebwerkseinlaufrohres mit einer radarreflektierenden, aber luftdurchlässigen Gitterstruktur an der Eingangsöffnung,1 shows a longitudinal section of an engine inlet pipe with a radar-reflecting but air-permeable lattice structure at the inlet opening,
Fig. 2 einen Querschnitt durch den Gegenstand von Fig. 1,2 shows a cross section through the object of FIG. 1,
Fig. 3 schematisch eine quadratische Maschengitterstruktur,3 schematically shows a square mesh structure,
Fig. 4 schematisch mehrere hintereinanderliegende Maschengitterstrukturen,4 schematically shows a plurality of mesh structures lying one behind the other,
Fig. 5 eine Hohlleiterstruktur mit quadratischem Gitterquerschnitt,5 shows a waveguide structure with a square lattice cross section,
Fig. 6 eine Hohlleiterstruktur mit sechseckigem wabenförmigern Gitterquerschnitt,6 shows a waveguide structure with a hexagonal honeycomb cross-section,
Fig. 7 einen Längsschnitt eines Tri ebwerkseinlaufrohrs mit einer Hohlleiterstruktur unterschiedlicher Länge der Elemente,7 shows a longitudinal section of an engine inlet pipe with a waveguide structure of different length of the elements,
Fig. 8 einen Längsschnitt eines Triebwerkseinlaufrohrs mit einer Hohlleiterstruktur mit Trichtern an beiden Enden der Elemente, Fig. 9 eine Variante des Gegenstandes von Fig. 8 mit Leitblechen in der Trichteröffnung der Elemente,8 shows a longitudinal section of an engine inlet pipe with a waveguide structure with funnels at both ends of the elements, 9 shows a variant of the object of FIG. 8 with baffles in the funnel opening of the elements,
Fig. 10 einen Längsschnitt durch ein Element der Hohlleiterstruktur nach Fig. 9 mit Leitblechen in der Trichteröffnung,10 shows a longitudinal section through an element of the waveguide structure according to FIG. 9 with guide plates in the funnel opening,
Fig. 11 einen Querschnitt durch die Öffnung des Trichters nach Fig. 10 und11 shows a cross section through the opening of the funnel according to FIGS. 10 and
Fig. 12 einen Längsschnitt eines schrägen Triebwerkseinlaufrohrs mit entsprechender Hohlleiterstruktur.Fig. 12 is a longitudinal section of an oblique engine inlet pipe with a corresponding waveguide structure.
Figur 1 zeigt einen Längsschnitt eines Triebwerkseinlaufrohrs mit einer radarreflektierenden, aber luftdurchlässigen Gitterstruktur an der Eingangsöffnung; Figur 2 den Querschnitt durch den Gegenstand von Figur 1 und Fig. 3 schematisch eine quadratische Maschengitterstruktur.FIG. 1 shows a longitudinal section of an engine inlet pipe with a radar-reflecting but air-permeable lattice structure at the inlet opening; Figure 2 shows the cross section through the subject of Figure 1 and Fig. 3 schematically shows a square mesh structure.
Zur Radartarnung des Triebwerkseinlaufs 1 ist gemäß der Erfindung dessen Öffnung durch eine gezielt radarreflektierende, luftdurchlässige Struktur 2 in viele Zellen bzw. Kanäle mit kleinerer Öffnung unterteilt, welche einerseits aufgrund ihrer Dimensionierung die einfallenden elektromagnetischen Wellen nicht in das Innere des Triebwerkseinlaufs eindringen lassen, sondern wie an einer leitenden Ebene gezielt reflektieren und andererseits dem Luftstrom einen möglichst geringen Reibungswiderstand entgegensetzen.To camouflage the radar of the engine inlet 1, according to the invention, its opening is divided into many cells or channels with a smaller opening by a specifically radar-reflecting, air-permeable structure 2, which on the one hand, due to their dimensioning, do not allow the incident electromagnetic waves to penetrate into the interior of the engine inlet, but rather how Reflect specifically on a conductive plane and on the other hand oppose the lowest possible frictional resistance to the air flow.
Die einfachste Vorrichtung zur Durchführung dieses Verfahrens ist gemäß den Figuren 1 bis 3 dadurch realisiert, daß die Struktur 2 aus einem Maschengitter 3 besteht, das aufgrund entsprechender Dimensionierung der Maschenweite d ( d <λMIN/2 mit λMIN als kleinster zu reflektierende Wellenlänge) für die einfallenden elektromagnetischen Wellen als Hochpaß wirkt und daher Wellen unterhalb seiner Grenzfrequenz reflektiert. Gemäß Figur 4 kann diese Struktur noch dadurch verbessert werden, daß sie aus mehreren, in bestimmtem Abstand aufeinanderfolgenden Maschengittern 4 aufgebaut wird, die für die elektromagnetische Welle einen Hochpaß entsprechend höherer Ordnung bilden und daher bessere Reflexionseigenschaften als ein einfaches Gitter besitzen.The simplest device for carrying out this method is implemented according to FIGS. 1 to 3 in that the structure 2 consists of a mesh grating 3 which, due to the appropriate dimensioning of the mesh size d (d <λ MIN / 2 with λ MIN as the smallest wavelength to be reflected) acts as a high pass for the incident electromagnetic waves and therefore reflects waves below its cutoff frequency. According to FIG. 4, this structure can be further improved in that it is built up from a plurality of mesh gratings 4 which follow one another at a certain distance and which form a high-pass filter of a corresponding higher order for the electromagnetic wave and therefore have better reflective properties than a simple mesh.
Eine weitere Verbesserung ergibt sich, wenn gemäß Figur 5 die Struktur aus quadratischen Hohlleiterkanalen mit einer Hohl! eiterbreite d < λMIN/2 und einer Hohlleiterlänge 1 > λMIN besteht. Eine Verbesserung aerodynamischer Eigenschaften kann dadurch erreicht werden, daß die Struktur gemäß Fig. 6 aus Hohlleiterkanalen mit dem Querschnitt eines regelmäßigen wabenartigen Sechsecks mit der Hohlleiterbreite d < λMIN/2 und der Höhlleiterlänge 1 > λMIN besteht.A further improvement is obtained if, according to FIG. 5, the structure consists of square waveguide channels with a hollow! pus width d <λ MIN / 2 and a waveguide length 1> λ MIN . An improvement in aerodynamic properties can be achieved in that the structure according to FIG. 6 consists of waveguide channels with the cross section of a regular honeycomb hexagon with the waveguide width d <λ MIN / 2 and the hollow conductor length 1> λ MIN .
Eine Steuerung der Reflexion in bestimmte, beispielsweise dem Standort der Detektoren abgewandte Richtungen kann dadurch erfolgen, daß gemäß Figur 7 die Längen der einzelnen Hohlleiterkanäle zum Zweck der Steuerung der Reflexion in bestimmte Richtungen unterschiedlich sind.The reflection can be controlled in certain directions, for example away from the location of the detectors, in that, according to FIG. 7, the lengths of the individual waveguide channels are different for the purpose of controlling the reflection in certain directions.
Zur weiteren Verbesserung aerodynamischer Eigenschaften kann der Hohlleiterkanal, wie in Figur 8 dargestellt, wie bei einer Hornantenne vorn und/oder hinten eine Trichteröffnung aufweisen.To further improve aerodynamic properties, the waveguide channel, as shown in FIG. 8, can have a funnel opening at the front and / or rear as in the case of a horn antenna.
Zur Verminderung von Phasenunterschieden an der Trichteröffnung kann die Struktur im Trichter gemäß Figur 9 Leitbleche aufweisen. Dadurch wird eine kürzere Bauweise bei äquivalenten elektromagnetischen Reflexionseigenschaften erzielt und die Aerodynamik weiter verbessert. Figur 10 zeigt einen Längsschnitt durch ein Element der Hohlleiterstruktur mit Leitblechen in der Trichteröffnung und Figur 11 einen Querschnitt durch die Öffnung des Trichters nach Fig. 10.In order to reduce phase differences at the funnel opening, the structure in the funnel according to FIG. 9 can have guide plates. This results in a shorter design with equivalent electromagnetic reflection properties and further improves the aerodynamics. FIG. 10 shows a longitudinal section through an element of the waveguide structure with baffles in the funnel opening and FIG. 11 shows a cross section through the opening of the funnel according to FIG. 10.
Gemäß Figur 12 kann die erfindungsgemäße Struktur auch bei schrägen Einlaufstutzen verwendet werden. Um die aerodynamischen Eigenschaften noch weiter zu verbessern, sind zweckmäßig die Kanten der Struktur messerscharf ausgebildet.According to FIG. 12, the structure according to the invention can also be used with inclined inlet connections. In order to further improve the aerodynamic properties, the edges of the structure are expediently razor-sharp.
Das beschriebene Verfahren und die gezeigten Vorrichtungen erscheinen effektiver als Absorptionsmaßnahmen innerhalb des Triebwerkseinlaufs und sind in der Praxis auch leichter realisierbar, sofern die Veränderung der aerodynamischen Eigenschaften bei der Triebwerkskonzeption berücksichtigt wird. The described method and the devices shown appear more effective than absorption measures within the engine inlet and are also easier to implement in practice, provided the change in aerodynamic properties is taken into account in the engine design.

Claims

Patentansprüche Claims
1. Verfahren zur Radartarnung von Triebwerkseinläufen bei Fluggeräten, dadurch g e ke n n z e i c h n e t , daß zur Reduzierung des globalen Radarquerschnitts des gesamten Fluggeräts die Öffnungen der Triebwerkseinläufe durch gezielt radarreflektierende, luftdurchlässige Strukturen in mehrere Zellen bzw. Kanäle mit kleineren Öffnungen unterteilt werden, welche einerseits aufgrund ihrer Dimensionierung die einfallenden elektromagnetischen Wellen nicht in das Innere des Triebwerksei nl aufs eindringen lassen, sondern wie an einer leitenden Ebene gezielt reflektieren und andererseits dem Luftstrom einen möglichst geringen Reibungswiderstand entgegensetzen.1. A method for radar camouflaging engine inlets in aircraft, characterized by the fact that, in order to reduce the global radar cross section of the entire aircraft, the openings of the engine inlets are divided into several cells or channels with smaller openings by radar-reflecting, air-permeable structures, which, on the one hand, due to their Dimensioning does not allow the incident electromagnetic waves to penetrate into the interior of the engine cable, but instead reflects them as if on a conductive plane and, on the other hand, opposes the air flow with the lowest possible frictional resistance.
2. Vorrichtung zur Durchführung des Verfahrens nach Anspruch 1, dadurch g e ke n n z e i c h n e t , daß die Struktur aus einem Maschengitter besteht, das aufgrund entsprechender Dimensionierung der Maschenweite d ( d < λMIN/2 mit λMIN als kleinster zu reflektierende Wellenlänge) für die elektromagnetischen Wellen als Hochpaß wirkt und daher Wellen unterhalb seiner Grenzfrequenz reflektiert.2. Apparatus for carrying out the method according to claim 1, characterized in that the structure consists of a mesh which, due to the appropriate dimensioning of the mesh size d (d <λ MIN / 2 with λ MIN as the smallest wavelength to be reflected) for the electromagnetic Waves act as a high pass and therefore reflect waves below its cutoff frequency.
3. Vorrichtung nach Anspruch 1, dadurch g e k e n n z e i e b n e t , daß die Struktur aus mehreren, in bestimmtem Abstand aufeinanderfolgenden Mascheggittern besteht, die für die elektromagnetische Welle einen Hochpaß entsprechend höherer Ordnung bilden.3. Device according to claim 1, characterized in that the structure consists of a plurality of mesh grids which follow one another at a certain distance and form a high-pass filter corresponding to the higher order for the electromagnetic wave.
4. Vorrichtung nach Anspruch 1, dadurch g e ke n n z e i e b n e t , daß die Struktur aus quadratischen Hohlleiterkanalen mit einer Hohlleiterbreite d < λMIN/2 und einer Hohll eiterlänge 1 > λMIN besteht. 4. The device according to claim 1, characterized ge ke nnzeiebnet that the structure consists of square waveguide channels with a waveguide width d <λ MIN / 2 and a hollow conductor length 1> λ MIN .
5. Vorrichtung nach Anspruch 4, dadurch g e ke n n z e i c h n e t , daß die Struktur aus Hohlleiterkanälen mit dem Querschnitt eines regelmäßigen wabenartigen Sechsecks mit einer Hohlleiterbreite d < λMIN/2 und einer Hohlleiterlänge 1 > λMIN besteht.5. The device according to claim 4, characterized in that the structure consists of waveguide channels with the cross section of a regular honeycomb hexagon with a waveguide width d <λ MIN / 2 and a waveguide length 1> λ MIN .
6. Vorrichtung nach Anspruch 4 oder 5, dadurch geke n nz e i c h n e t , daß die Längen der einzelnen Hohlleiterkanäle zum Zweck der Steuerung der Reflexion in bestimmte Richtungen unterschiedlich sind.6. The device according to claim 4 or 5, characterized in that the lengths of the individual waveguide channels are different in certain directions for the purpose of controlling the reflection.
7. Vorrichtung nach Anspruch 4, dadurch g eke n nz e i c hn e t , daß die Struktur vor und/oder hinter dem Hohlleiterkanal eine Trichteröffnung aufweist.7. The device according to claim 4, characterized in that the structure has a funnel opening in front of and / or behind the waveguide channel.
8. Vorrichtung nach Anspruch 7, dadurch geken nz e i e bn e t , daß die Struktur im Trichter zur Verminderung von Phasenunterschieden an der Trichteröffnung Leitbleche aufweist.8. The device according to claim 7, characterized in that the structure in the funnel has baffles for reducing phase differences at the funnel opening.
9. Vorrichtung nach einem der vorhergehenden Ansprüche, dadurch g ekenn ze i c h n et , daß der Einlaufstutzen schräg ist.9. Device according to one of the preceding claims, characterized in that the inlet connection is inclined.
10. Vorrichtung nach einem der vorhergehenden Ansprüche, dadurch g eken nze i c h n et , daß die Kanten der Struktur zur Verbesserung der aerodynamischen Eigenschaften scharf ausgebildet sind. 10. Device according to one of the preceding claims, characterized in that the edges of the structure are sharp to improve the aerodynamic properties.
PCT/EP1987/000745 1986-12-03 1987-12-01 Process and device for camouflaging power unit inlets WO1988004479A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863641289 DE3641289A1 (en) 1986-12-03 1986-12-03 METHOD AND DEVICE FOR WHEEL ARMING OF ENGINE INLETS
DEP3641289.9 1986-12-03

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WO1988004479A1 true WO1988004479A1 (en) 1988-06-16

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EP (1) EP0291523A1 (en)
DE (1) DE3641289A1 (en)
WO (1) WO1988004479A1 (en)

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RU2650701C1 (en) * 2016-10-25 2018-04-17 Федеральное государственное казенное военное образовательное учреждение высшего образования "Военный учебно-научный центр Военно-воздушных сил "Военно-воздушная академия имени профессора Н.Е. Жуковского и Ю.А. Гагарина" (г. Воронеж) Министерства обороны Российской Федерации Method of reducing radar visibility of the airplane scoop of airplane generator and the device its realizing

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US3487410A (en) * 1968-01-08 1969-12-30 North American Rockwell Screening for engines

Cited By (6)

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Publication number Priority date Publication date Assignee Title
WO1995008473A1 (en) * 1993-09-20 1995-03-30 United Technologies Corporation A duct cover for directing a fluid therethrough and a method for making the same
US5558919A (en) * 1993-09-20 1996-09-24 United Technologies Corporation Duct cover for directing a fluid therethrough
AU679116B2 (en) * 1993-09-20 1997-06-19 United Technologies Corporation A duct cover for directing a fluid therethrough and a method for making the same
US7198954B1 (en) * 1999-02-03 2007-04-03 The Trustees Of Columbia University In The City Of New York Methods for predicting pregnancy outcome in a subject by hCG assay
US9284046B2 (en) 2011-02-14 2016-03-15 Alenia Aermacchi Spa Aircraft with improved aerodynamic performance
RU2597739C1 (en) * 2015-04-22 2016-09-20 Николай Евгеньевич Староверов Method of masking air intake (versions)

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EP0291523A1 (en) 1988-11-23
DE3641289A1 (en) 1988-06-16

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