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.