Stealth Aircraft-History, Technology and Outlook

Sweetman, Bill

doi:10.1115/90-gt-172

Cited by 5 publications

(3 citation statements)

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“…A low RCS can be achieved by combining both the scattering and absorption methods in the project of the aircraft. Good examples of this traditional combination are the Lockheed SR-71 Blackbird [ 43 ] and the Lockheed-Martin F-117 Nighthawk [ 44 ] aircraft.…”

Section: Methodsmentioning

confidence: 99%

Metasurfaces and Blinking Jamming: Convergent Study, Comparative Analysis, and Challenges

Mello

2023

Micromachines

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Blinking jamming is an active self-screening technique performed by at least two aircraft to tackle monopulse radars and all complexity related thereto. Nowadays, the technique can be performed with digital radiofrequency memories (DRFMs), which are cumbersome, complex, expensive, need a dedicated compartment and antenna, and introduce spurs in the signals. In this paper, we propose an alternative to the implementation of blinking jamming with DRFMs, namely with reconfigurable metasurfaces. By covering the aircraft parts that most contribute to the radar cross-section (RCS), reconfigurable metasurfaces can interchangeably absorb or amplify impinging waves, making the aircraft ‘blink’ from the radar perspective. To validate the feasibility, simulations accounting for realistic phenomena are conducted. It is seen that, if the aircraft RCS can be varied in a ratio of 10:1, either with absorptive or power-amplifying metasurfaces, a performance similar to that of the DRFM is achieved. Furthermore, a ratio of 2:1 is sufficient to make the radar antenna system movements exceed the angular range of the formation. We also anticipate our work to be a starting point for completely new ways of countering radars, e.g., with countless small drones performing passive or active stand-off blinking jamming.

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Section: Methodsmentioning

confidence: 99%

Metasurfaces and Blinking Jamming: Convergent Study, Comparative Analysis, and Challenges

Mello

2023

Micromachines

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“…Illustration of A-12's absorbent structure: acute wedge shape traps any incident radar beam, causing it to reflect from one side of the wedge to the other, as its energy is gradually absorbed into the RAM[48].The most suitable inlet location, from the low observable point of view (for a ground-based radar), is on top of the aircraft, i.e. top-mounted or dorsal inlets.A classical example is the F-107A.…”

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confidence: 99%

System Design Aspects of Propulsion Education in Aerospace Engineering Curricula

Farokhi¹

1991

International Journal of Turbo and Jet Engines

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In the present paper, the inadequacies of the traditional approach to undergraduate propulsion education are discussed. Propulsion as a system endeavor, in contrast to a single discipline, demands a system design education provided in a capstone engine design course in the senior year of aerospace engineering curricula. A suitable course content is proposed, and two examples of recent experiences at the University of Kansas with the AIAA National Airbreathing Engine Design competition are briefly presented. *Associate Professor; Member AIAA Brought to you by | University of Arizona Authenticated Download Date | 7/17/15 3:02 PM R Gas constant = R/MW SFC Specific fuel consumption TR Thrust reversing TV Thrust vectoring T ref Reference temperature = 520°R W Weight W K2 Corrected mass flow rate at compressor face Ξ M 2 /9 2 /6 2 X Semi-major axis of a bisuper ellipse (defined in Fig. 6) Y Semi-minor axis of a bisuper ellipse (defined in Fig. 6) Y M Ξ °MAX ~ d HL α Angle of attack ß Angle of spoiled sector for circumferential distortion π ά Inlet total pressure recovery •Θ--< Ratio of specific heats for a gas Average subsonic diffuser wall angle Brought to you by | University of Arizona Authenticated Download Date | 7/17/15 3:02 PMConventional Approach: Teaching Fundamentals Aerothermodynamic analysis of airbreathing engines constitutes the heart and soul of traditional undergraduate propulsion education. For this purpose, a brief review of thermodynamic principles applied to both a system and control volume is given in the first week of a propulsion course. Steady, one-dimensional flow of a perfect gas is then reviewed with applications to Rayleigh, Fanno, and shock flow. Cycle analysis and derivation of engine performance parameters mark the official beginning of a propulsion course. Here, cycle thermal and propulsive efficiencies and their respective limitations are discussed; and various airbreathing engine types, from turboprops to high-bypass-ratio turbofan engines, and from turbojets with reheat to conventional ramjets, find their suitable flight operating range. At this point, the students may be introduced to the performance gains obtained through concepts such as variable-cycle engines, counter-rotating advanced turboprops, and multimode hybrid propulsion. Cycle parametric investigation for the purpose of obtaining optimum solutions, both analytically and numerically, is advocated by Oates 11 ' 5 . It serves a very good purpose in that it provides deeper understanding and appreciation in students for widely differing requirements of low-and high-speed flight. Aircraft engine components analysis-i.e. inlets and nozzles, combustors and afterburners, and turbomachinery-then constitute the bulk of the propulsion course. The material continues into component matching and off-design analysis of airbreathing engines. At this point, the operational attractiveness and difficulties of implementation of a variable-area turbine (VAT) compared to conventional fixed-area turbine (FAT) could be appreciated by students Stre...

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“…The stealth technology since the second world war has been one of the most studied topics because this type of technology allows reducing the observability of radiant structures through the reduction of the radar cross-section (RCS), which has been integrated into aircraft, submarines, missiles. The first applications in fighter aircrafts beyond the angle of the fuselage used a special type of paint as absorbent, causing electromagnetic waves that reached the object not to be reflected [173]. Subsequently, structures with corrugated surfaces were used, generating a deviation from the electromagnetic waves impinging on the surface of the object [174].…”

Section: Metasurface Antenna Absorbermentioning

confidence: 99%

Design of Multi-feed UWB Antennas using the Theory of Characteristic Modes

Peñafiel-Ojeda¹,

Ramiro²

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Stealth Aircraft-History, Technology and Outlook

Cited by 5 publications

References 0 publications

Metasurfaces and Blinking Jamming: Convergent Study, Comparative Analysis, and Challenges

Metasurfaces and Blinking Jamming: Convergent Study, Comparative Analysis, and Challenges

System Design Aspects of Propulsion Education in Aerospace Engineering Curricula

Design of Multi-feed UWB Antennas using the Theory of Characteristic Modes

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