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INTRODUCTION
Stealth technology referred as “VLO” ie “VERY LOW
OBSERVABLE TECHNOLOGY”
•
•Fighter
planes are made so they are harder to be
detected by the radar and other devices
•The
first combat use of stealth aircraft was in December
1989 during Operation Just Cause in Panama
•Well
known examples include the United States' F-117
Nighthawk (1980s-2008), the B-2 Spirit "Stealth Bomber,"
and the F-22 Raptor
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HISTORY
•The
first true "stealth"
aircraft may have been
the Horten Ho
229 flying
wing fighter-bomber,
developed in
Germany during the
last years of WWII.
•SR
71 the first Stealth
airplane launched. It is
well known as 'black
bird'.
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STEALTH
TECHNOLOGY
•The
goal of stealth technology is to make an airplane invisible
to radar
•There
are two different ways to create invisibility:
1.
The airplane can be shaped so that any radar signals it
reflects are reflected away from the radar equipment.
2.
The airplane can be covered in materials that absorb radar
signals
•stealth
aircraft has to be stealthy in six disciplines: radar,
infrared,
visual, acoustic, smoke and contrail.
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coventional aircraft
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stealth fighter
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SHAPING OF STEALTH
•The
shape should be flat or rectilinear and at the same time
oblique to the incoming waves
•Another
method bounce back on a very limited number of
directions, maybe only one or two
•a
compact, smoothly blended external geometry to achieve a
continuously varying curvature
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RAM & RAS
RAM
Reffers to “RADAR ABSORBENT MATERIALS”
Most such material consists of an active ingredient—a
dielectric, such as carbon, or magnetic ferrites—which is
moulded into a non-lossy dielectric matrix, usually a plastic of
some kind.

RAS
reffers to “RADAR ABSORBENT STRUCTURE”
To
achieve a high degree of absorption over a wide
bandwidth is to use “honeycomb “ structure
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ACTIVE
CANCELLATION
•Active
cancellation
is a theoretical
military
jamming system tha
t involves the
sampling of an
incoming radar
signal, analyzing it,
then returning ths
signal slightly out of
phase, thus
"cancelling" it out.
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PLASMA STEALTH
•Plasma
stealth is a proposed process that uses ionized
gas (plasma) to reduce the radar cross se ction (RCS) of
an aircraft.
•conductivity
of the plasma allows it to interact
strongly with the incoming radio wave, but the wave
can be absorbed and converted into thermal energy
rather than reflected.
•plasma
might also be used to modify the reflected
waves to confuse the opponent's radar system
•Absorption
of EM RADIATION by plasma stealth
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DETECTION BY INFRARED
RADIATION
•Passive
IR detection devices rely on the fact that every atom of
matter, including clouds and rain, continuously sends out
electromagnetic radiation at an IR wavelength which
corresponds to its temperature.
•For
aircraft detection, IR seekers look for contrasts between hot
parts on the airframe
•
•In
engine exhausts, carbon dioxide produces most of the IR
signature at 4.2 microns
•IR
sensors can 'see' at two different wavelengths, (medium: 3-5
microns and long:8-14 microns) to provide good target
discrimination.
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INFRARED STEALTH
•to
degrading the performance of IRST systems is to ensure
that the exhaust dissipates as quickly as possible after
leaving the aircraft.
• Some of the techniques are follows
1. engines can be fitted with flow mixers to blend the cold
bypass air with the hot air that passes through the
combustor and the turbine
2.
The exhausts geometry can be adapted to a wide and flat
shape
3.
Interaction between the exhaust stream and the airflow
over the aircraft can be engineered to create an
additional vortex which further promotes mixing
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OTH Radar (Over the Horizon Radar)
•Over-the-horizon
radar is a
design concept that increases
radar's effective range over
conventional radar
•It
is claimed that the Australian
JORN Jindalee Operational Radar
Network can overcome certain
stealth characteristics.
•It
is claimed that the HF
frequency used and the method of
bouncing radar from ionosphere
overcomes the stealth
characteristics of the F-117A.
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USE OF STEALTH
AIRCRAFT
stealth aircraft have been
used in
•conflicts,
including Operation Desert
Storm, Operation Allied
Force and the 2003 invasion
of Iraq.
•employed
to strike highvalue targets
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NOT
STEALTH
DO NOT HAVE BAY DOORS
STEALTH
– THE TWO SIDE-BAY
DOORS ARE OPEN HERE
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SUMMARY
•Stealth
technology referred as “VLO” ie “VERY LOW OBSERVABLE
TECHNOLOGY”
•first
true "stealth" aircraft may have been the Horten Ho 229 flying wing
•The
goal of stealth technology is to make an airplane invisible to radar
•RAM
reffers to “RADAR ABSORBENT MATERIALS” .RAM Reffers to
“RADAR ABSORBENT MATERIALS” .
•Active
cancellation is a theoretical military jamming system
•
•Plasma
stealth is a proposed process that uses ionized gas (plasma) to
reduce the radar cross se ction (RCS) of an aircraft.
•to
degrading the performance of IRST systems is to ensure that the exhaust
dissipates as quickly as possible after leaving the aircraft.
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