STEALTH TECHNOLOGY AND IT’S APPLICATIONS IN

AIRCRAFTS

What Is Stealth Technology? Scientifically known as

low observatory

Used in Military aviation

Reduces detection range of an aircraft

Similar to camouflage tactics used by soldiers

Partial invisibility to radar and other detection

RADAR SIGNATURE ? A radar signature is how big the airplane on radar appears

from a specific angle and distance.

Radar cross section (RCS): the cross

sectional area of a perfectly reflecting

sphere that would produce the same

signal reflection as would the object.

Depends on many parameters, like:

Relative size (size vs. wavelength).

Target material /painting.

Shape / orientation.

The size of a target's image on radar is measured by RCS (σ )

Uses the principle of reflection and absorption as well as redirection.

Minimizes heat and other emissions from engine and other spots.

Reduces RCS by surface designs of stealth aircrafts by RAS or RAM

How It Reduces RCS ?The job is performed by using mainly

two techniques:

1.Designing of surface

2.Radar absorbing materials(RAM)

But now a days one more technologyknown as “Plasma Stealth Technology” isalso employed

1. Surface Design The goal of stealth technology is to

make an airplane almost invisible

to radar.

Most conventional aircraft have

a rounded shape which means

that no matter where the radar

signal hits the plane, some of the

signal gets reflected back

The shape of an stealth airplane

is designed in such a way that it

reflects the signals away from the

radar. As shown in the fig. here:

Precautions In Designing: Sharp Edges

Design of nose

Acute angles

No right angle

The air craft must

bury the engines

within the wings

E.g. Lockheed

F-117 Nighthawk

Northrop Grumman B-2 Spirit Has a completely different design: It has one big

wing, like a boomerang.

This flying wing design is much more efficient than a conventional plane. As shown:

B-2 continued..It eliminates the tail and fuselage & also reduces drag i.e. the

total force of air resistance acting on the plane.

Greater efficiency helps the B-2 travel long distances in a short period of time.

It is high subsonic, means its top speed is just around the speed of sound (around 305 m/s ) but it can go 6,900 miles (11,000 km) without refueling and 11,500 miles (18,500 km)

with one in-flight refueling.

The stealth bomber's peculiar shape deflects radio beams in both ways.

Differences Between Normal Aircraft & Stealth Aircraft

1. Tail Angle Effect:

A corner reflector is retro reflector

which consists of three mutually

perpendicular, intersecting flat

surfaces, & hence reflects em

waves back to source.

So tail angle should be kept acute to

decrease detection. As Shown below:

•Exhaust Plume of a normal Aircraft

• Stealth Aircraft without Exhaust.

4. Exhaust plume

2. Difference In Aircraft Design

When we are using normal shape

When using stealth technology.

Normal fighter plane showing the engine.

Engines of the stealth aircraftare covered.

3. Engine position

2. Radar Absorbing Materials(RAM)

Nano structural composite material,

absorbing without reflection radar

wave.

Magnetic ferrite-based substance

RAM reduces the radar cross

selection making the object

appear smaller.

Radiation Absorbing honeycomb

Structural material usually incor-

porated with skin of aircraft

Frequency Selective Surfaces(FSS) Planar periodic structures that behave like filters to

electromagnetic energy.

They are like metallic

screens with frequency

selective properties

Used as ‘spatial filters’

through which a specific

range of Em energy

may be propagated

The Lockheed Martin F-35 Lightning II usesnew stealthy radar absorbent material in itsconstruction which includes fiber-mat.

Plasma Stealth The Russian Scientists proposed to create a plasma formation

around protected object.

The aircraft injects a stream of ionized

gas in the form of plasma cloud.

Prevents radars from seeing it by

absorbing the radar energy in this

plasma cloud

The artificially created plasma cloud surrounding the plane reduces its RCS by a factor of 100.

Infrared Stealth Infra-red radiation are emitted by all matter above

absolute temperature zero

Hot zones such as engine exhaust , wing surface [ friction due to air ] get heated which rather increases the visibility.

These part should be kept cool as possible it can be ,

Option would be mixing of cool air with the hot engine exhaust .

Use compressed gas or liquid nitrogen to cool their internal parts.

Stealth Technology Today The F-117A, B-2 and B1-B can be regarded as the three

emblematic LO aircraft of the late '80s.

The famous F-22A Raptor (1st flight in 1997,production ended in 2011, with 195planes built, 182planes operating today) is a Lockheed Martin’s (L.M.)5th generation air superiority stealth fighter.

The Lockheed Martin (L.M.) F-35 Lightning II.

A multirole 5th generation fighter with stealthcapabilities (first flight in 2006, currently in initialproduction and testing).

The Sukhoi PAK FA A 5th gen., multirole, twin-engine jet fighter, developed

by Sukhoi for the Russian Air Force

Its prototype, T-50, flew

for the first time in 2010

Based on PAK FA,

Sukhoi will develop

with HAL (Hindustan

Aeronautics Limited),

the “5th Generation

Fighter Aircraft”

(FGFA) for India.

Stealth Technology In Future Although U.S. is the dominating country having

most advanced stealth aircrafts but

Advantages Reduces the causality rates during war

Saving military budget.

Utmost importance in anti

terrorist operations

Develop the military secretes

Bluff the anti-detective device

Stealth aircraft are invisible to

Radar

Actually a fight between radar

technology and stealth technology

Disadvantages Still not a guaranteed technology

Not much reliable

Most of the Stealth Aircrafts can’t fly fast. However technical advancements re making them capable of it,

They are not maneuverable.

Can carry only limited amount of payload.

High cost of maintenance.

Very economic.

Reliability hugely depends upon the tracking radar system.

Conclusions A technology of future

Lots of opportunities lies for scientists, researchers as wellas for students also.

Success yet to be proved extensively.

Huge investment is required.

Opportunity for developing countries to learn thetechnology.

Consider as a war between radar technology and stealthtechnology.

U.S is the leading country with other countries alsoinvesting a huge amount of their investments in thetechnology.