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Watercraft Stealth
Technologies
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{
Stealth ShipA ship which employs stealth technology construction techniques in
an effort to ensure that it is harder to detect by one or more of radar,
visual, sonar, and infrared methods. These techniques borrow from
stealth aircraft technology, although some aspects such as wake and
acoustic signature reduction are unique to stealth ships' design.
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Radar cross section (RCS) is a measure of how detectable anobject is with a radar. A larger RCS indicates that an object ismore easily detected.
An object reflects a limited amount of radar energy. A number ofdifferent factors determine how much electromagnetic energyreturns to the source such as:
material of which the target is made;
absolute size of the target;
relative size of the target (in relation to the wavelength of theilluminating radar);
the incident angle (angle at which the radar beam hits aparticular portion of target which depends upon shape of targetand its orientation to the radar source);
reflected angle (angle at which the reflected beam leaves thepart of the target hit, it depends upon incident angle);
Radar Cross Section (RCS)
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In designing a ship with reduced radar signature, the main concernsare radar beams originating near or slightly above the horizon (asseen from the ship) coming from distant patrol aircraft, other ships
or sea-skimming anti-ship missiles with active radar seekers.
Therefore, the shape of the ship avoids vertical surfaces, whichwould perfectly reflect any such beams directly back to the emitter.Retro-reflective right angles are eliminated to avoid causing thecat'seyeeffect. A stealthy ship shape can be achieved by constructing the
hull and superstructure with a series of slightly protruding andretruding surfaces. This design was developed by several Germanshipyards, and is thus extensively applied on ships of the GermanNavy.
Stealth Ship Shaping
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Stealth Ship Examples
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{
An experimental stealth shipbuilt by Lockheed for theUnited States Navy.
Though the program wasbegun in the mid-1980s but itwas only in 1993-1994, thecraft was revealed to thepublic.
Has only 12 bunks aboard &max it can take 24 at once tosea, it doesn't have muchroom for a large crew.Measuring a bit over 160-feet-long it has one smallmicrowave oven, a
refrigerator & table.
Sea Shadow
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{Designed to elude radar
detection, acoustic detection,
infrared detection & visual
detection, it was the first
stealth ship to enter service.
Carbon fiber reinforced
plastic is used to construct itssurface.
Visby
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{
The Stiletto, a Twin M hull vessel, is 80
ft in length providing a rectangular area
equivalent to a conventional
displacement craft 160 ft in length. The
vessel's draft fully loaded is 3 ft and isdesigned for a speed of 50-60 kts.
The design and construction of this
vessel made from carbon fiber for
reduced weight and added rigidity.
Largest U.S. Naval vessel built using
carbon fibre composite and epoxybuilding techniques, which yields a very
light, but strong hull.
Has been popular for its efficiency, low
cost, innovation, higher payload fraction,
agility, shock mitigation, shallow draft
and stealth which are the new prioritiesfor the next generation naval craft.
M80 Stiletto
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{Sea Jet, with a length of morethan 133-foot & a full load
displacement of 120 tons
[239,000 pounds] houses a
Rolls Royce Naval Marine
advanced water jet propulsion
system, the AWJ-21, which
improves surface shipefficiency & maneuverability
by reducing noise & wake.
Sea Jet
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{
It is tall enough to withstand
high sea states, yet foldable so
it can be taken aboard mother
ships and can operate in very
shallow waters," explains a
spokesman for the Lockheed
Martin Maritime Systems &
Sensors division, which is
based in Moorestown, N.J.
The roughly 36-ft.-long craftwould ride on a pair of buoyant
pods. With the pods drawn
inward, CHARC would sit
about 14 ft. above the
waterline. CHARC could avoid
visual, radar and infrared
detection as its water jetpropulsion system speeds it
along at 60 knots.
Charc
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{The currently developed
under DD(X) - is the US
version of a stealth ship.
DDG-1000
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{
A new range of superfast,
large stealth missile craft,also known as MTBs
(missile torpedo boats).
The word Skjold means
shield in Norwegian. The
flexibility inherent in Skjold
is interesting also to other
navies.
They are among the fastest
warships in the world and
can reach speeds of up to 60
knots / 110 km/t.
Skjold ClassPatrol Boats
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{Its hull form design can
enhance the sea keeping
capability of future small
combatant craft.
Sea Lion
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{It's a stealth look alike,
which has lots of windows,
perhaps a rich & famous
prized possession.
Navy Seals Boat
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Stealth Watercraft List
Braunschweig class corvette
De Zeven Provincin class frigate
Future Dutch Navy offshore patrol
vessels
Rotterdam class amphibious transportdock
F125 class frigate
Type 45 destroyer
Formidable class frigate
Hamina class missile boat
Kolkata Class Destroyer
Kedah class New Generation Patrol
Vessels
La Fayette class frigate
Littoral combat ship
Project 17A class frigate
Shivalik class frigate
Visby class corvette
Type 052C destroyer
Type 054A frigate
Zumwalt class destroyer
Houbei class missile boat Milgems
Tartarstan/Gepard class frigate
Project 21630 Buyan
Project 20380 Steregushchiy
Admiral Grigorovich class frigate
Gorshkov class frigate
Project 21956 destroyer
FREMM multipurpose frigates
Horizon CNGF
Skjold class patrol boat
Sea Shadow (IX-529)
Sachsen class frigate
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Intentional emission of radio frequency signals tointerfere with the operation of a radar by saturating its
receiver with noise or false information.
There are two types of radar jamming:Mechanical
andElectronic jamming.
Radar Jamming
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It is caused by devices which reflect or re-reflect radar
energy back to the radar to produce false target returns
on the operator's scope.
Mechanical jamming devices includechaff, corner
reflectors, and decoys.
Mechanical Jamming
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Madeof different length metallic strips, which reflect different
frequencies, so as to create a large area of false returns in which
a real contact would be difficult to detect.
It is oftenaluminum for weight purposes and is usually coated
with something such as a plastic to make it more slick and less
likely to bind up in large clumps.
Chaff
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Multiple-sided objects that re-radiate radar energymostly back toward its source. An aircraft cannot carry
as many corner reflectors as it can chaff.
Have the same effect as chaff but are physically very
different.
Corner Reflectors
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Maneuverable flying objects intended to deceive a radar
operator into believing that they are actually aircraft.
Dangerous: Can clutter up a radar with false targets
making it easier for an attacker to get within weapons
range and neutralize the radar.
Can be fitted on decoys to make them appear larger than
they are, thus furthering the illusion that a decoy is an
actual aircraft. Some decoys have the capability to
perform electronic jamming or drop chaff. Have a deliberatelysacrificial purpose i.e. defenders may
fire guided missiles at the decoys, thereby depleting
limited stocks of expensive weaponry which might
otherwise have been used against genuine targets.
Decoys
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A form ofElectronic Warfare where jammers radiate
interfering signals toward an enemy's radar, blocking
the receiver with highly concentrated energy signals.
The two main technique styles are noise techniques
and repeater techniques.
The three types ofnoise jamming are spot, sweep,and barrage.
Electronic Jamming
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Occurs when a jammer focuses all of its power on a
single frequency. While this would severely degradethe ability to track on the jammed frequency, a
frequency agile radar would hardly be affected
because the jammer can only jam one frequency.
While multiple jammers could possibly jam a range
of frequencies, this would consume a great deal ofresources to have any effect on a frequency-agile
radar, and would probably still be ineffective.
Spot jamming
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When a jammer's full power is shifted from one
frequency to another.
While this has the advantage of being able to jam
multiple frequencies in quick succession, it does not
affect them all at the same time, and thus limits the
effectiveness of this type of jamming. Although,
depending on the error checking in the device(s) this
can render a wide range of devices effectively
useless.
Sweep Jamming
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Jamming of multiple frequencies at once by a single
jammer.
Advantage: Multiple frequencies can be jammed
simultaneously; however, the jamming effect can be
limited because this requires the jammer to spread its
full power between these frequencies. So the morefrequencies being jammed, the less effectively each is
jammed.
Barrage Jamming
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Class of materials used in stealth technology todisguise a vehicle or structure from radar detection.
RAM cannot perfectly absorb radar at any frequency,but any given composition does have greaterabsorbency at some frequencies than others; there isno one RAM that is suited to absorption of all radarfrequencies.
Can significantly reduce an object's radar cross-sectionin specific radar frequencies, but it does not result in"invisibility" on any frequency. Bad weather maycontribute to deficiencies in stealth capability.
Radar Absorbent Material