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Stealth Stealth TechnologyTechnology

By Deepak JacobS7 LRoll No: 16MACE

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IntroductioIntroductionnMeans :- low

observable.Basic idea :- to

blend with the surroundings.

Quest :- began more than 60 years ago during World War II.

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Goal of Stealth Goal of Stealth TechnologyTechnology

To make aircraft invisible to RADAR

To reduce RADAR, IR, acoustic, visual and avionics signature

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Aircraft detection Aircraft detection methodsmethods

RADARHeat detectionTurbulence detectionVisual detectionAcoustic Detection

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How to get Stealthy…How to get Stealthy…

By reducing the imprint on radar

system

By turning down the heat of IR picture

By reducing the turbulence

By reducing the sound

By camouflaging the vehicle

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How Radar works…How Radar works…

Principle of Echo and Doppler effect

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◦ The amount of power reflected back to the radar depends largely on a quantity called the radar cross section (RCS)

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Received power Vs RangeReceived power Vs Range

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Defeating RADARDefeating RADARDiffraction – Scattering of RADAR energyAbsorption – Absorb RADAR energy and

transform and re-emit as heat energy

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RCS Reduction techniquesRCS Reduction techniques

Purpose shapingPurpose shaping◦ The shape of the target’s reflecting surfaces

is designed such that they reflect energy away from the source

Radar absorbent materialRadar absorbent material◦ As an addition to highly reflective surfaces

Active CancellationActive Cancellation◦ Target generates a radar signal equal in

intensity but opposite in phase to the predicted reflection of an incident radar signal

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Usual Aero planes Stealth aircrafts

Reduction by Radio wave Reduction by Radio wave scatteringscattering

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Angled Surfaces

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Internal Radar Absorbent Internal Radar Absorbent ConstructionConstruction

Special Radar Absorbent structure – re-entrant triangles

First used on SR-71 Blackbird

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Re entrant trianglesRe entrant triangles

RADAR beam

Traps radar energy and bounces it off internal faces dissipating the energy

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Principle behind Principle behind RAMRAM Coating contains

carbonyl iron ferrite.When a radar wave

encounters this coating, it creates a magnetic field within the metallic elements of the coating.

The field has alternating polarity and dissipates the energy of a radar signal. 16

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Three types of RAM◦Resonant◦Non-resonant magnetic ◦Non-resonant large volume

• Materials• carbon fiber composites

• magnetic ferrite-based substance RAM reduces the RCS by making the object

appearsmaller

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Plasma stealthPlasma stealth

Is a proposed process that uses ionized gas (plasma) to reduce the radar cross section (RCS) of an aircraft.

While it is theoretically possible to wrap the airframe in plasma, it is practically difficult.

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Plasma around a stealth Plasma around a stealth aircraftaircraft

Attained by electrostatic or RF discharges or by laser-produced plasmas

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Anti stealth / Counter Anti stealth / Counter stealthstealthBy triangulating its location with

a network of radar systems.With the help of microwaves

similar to the ones emitted by the cell phone towers.

By using over the horizon radar, ultra wide band (impulse) radar, bistatic radar, imaging radar and IR imaging seekers.

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Disadvantages of stealth Disadvantages of stealth technology technology

It cannot fly as fast or is not maneuverable like conventional aircraft.

The reduced amount of payload it can carry.

The cost. Stealth aircraft literally costs its weight in gold. B-2 ($2 billion), F-117 ($70 million) and the F-22 ($100 million) are the costliest planes in the world.

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ReferencesReferencesJournal of aerospace sciences &

technologies vol.59, no.3‘Introduction to radar systems’

Merrill I Skolnikwww.wikipedia.comwww.aerospaceweb.orgwww.ausairpower.netwww.centennialofflight.gov

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Thank YouThank You

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Questions???Questions???