Stealth technology - AbsoluteAstronomy.com

Stealth technology also termed LO technology (low observable technology) is a sub-discipline of military tactics and passive electronic countermeasures

Electronic countermeasures

An electronic countermeasure is an electrical or electronic device designed to trick or deceive radar, sonar or other detection systems, like infrared or lasers. It may be used both offensively and defensively to deny targeting information to an enemy...

, which cover a range of techniques

Technology

Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...

used with personnel, aircraft

Stealth aircraft

Stealth aircraft are aircraft that use stealth technology to avoid detection by employing a combination of features to interfere with radar as well as reduce visibility in the infrared, visual, audio, and radio frequency spectrum. Development of stealth technology likely began in Germany during...

, ships

Stealth ship

A stealth ship is a 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...

, submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s, and missiles, to make them less visible (ideally invisible) to radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

, infrared

Infrared

Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

, sonar

Sonar

Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

and other detection methods.

Development in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

occurred in 1958, where earlier attempts in preventing radar tracking of its U-2

Lockheed U-2

The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...

spy planes during the Cold War

Cold War

The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

by the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

had been unsuccessful. Designers turned to develop a particular shape for planes that tended to reduce detection, by redirecting electromagnetic waves

Electromagnetic radiation

Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

from radars. Radar-absorbent material was also tested and made to reduce or block radar signals that reflect off from the surface of planes. Such changes to shape and surface composition form stealth technology as currently used on the Northrop Grumman B-2 Spirit "Stealth Bomber".
The concept of stealth is to operate or hide without giving enemy forces any indications as to the presence of friendly forces. This concept was first explored through camouflage

Camouflage

Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

by blending into the background visual clutter. As the potency of detection and interception technologies (radar

Radar

, IRST, surface-to-air missile

Surface-to-air missile

A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

s etc.) have increased over time, so too has the extent to which the design and operation of military personnel and vehicles have been affected in response. Some military uniforms are treated with chemicals to reduce their infrared

Infrared

signature. A modern "stealth" vehicle will generally have been designed from the outset to have reduced or controlled signature

Spectral signature

Spectral Signatures are the specific combination of reflected and absorbed electromagnetic radiation at varying wavelengths which can uniquely identify an object. The spectral signature of stars indicates the spectrum according to the EM spectrum...

. Varying degrees of stealth can be achieved. The exact level and nature of stealth embodied in a particular design is determined by the prediction of likely threat capabilities.

History

In England, irregular units of gamekeepers in the 17th century were the first to adopt drab colours (common in the 16th century Irish units) as a form of camouflage

Camouflage

, following examples from the continent.

Yehudi lights

Yehudi lights

Yehudi lights are lamps placed on the underside or wing leading edge of an aircraft to raise luminance, to disguise the aircraft against the background sky. The technique was successfully employed in World War II by RAF Short Sunderland aircraft in attacks on U-boats.In 1945 a Grumman Avenger with...

were successfully employed in World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

by RAF

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

Shorts Sunderland aircraft in attacks on U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s. In 1945 a Grumman Avenger with Yehudi lights got within 3000 yards (2,743.2 m) of a ship

Ship

Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

before being sighted. This ability was rendered obsolete by the radar

Radar

of the time.

The U-boat U-480

German submarine U-480

U-480 was an experimental Kriegsmarine Type VIIC U-boat of World War II, considered by many to be the first stealth submarine. It was equipped with a special rubber coating that made it harder to detect by British ASDIC sonar.-The coating:The Germans developed a...

may have been the first stealth submarine. It featured a rubber coating, one layer of which contained circular air pockets to defeat ASDIC sonar.

One of the earliest stealth aircraft seems to have been the Horten Ho 229

Horten Ho 229

The Horten H.IX, RLM designation Ho 229 was a late–World War II prototype fighter/bomber designed by Reimar and Walter Horten and built by Gothaer Waggonfabrik...

flying wing. It included carbon powder in the glue to absorb radio waves. Some prototypes were built, but it was never used in action.

During the 1950s, the Avro Vulcan

Avro Vulcan

The Avro Vulcan, sometimes referred to as the Hawker Siddeley Vulcan, was a jet-powered delta wing strategic bomber, operated by the Royal Air Force from 1956 until 1984. Aircraft manufacturer A V Roe & Co designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced,...

, a British bomber

Bomber

A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...

, had a remarkably small appearance on radar despite its large size, and occasionally disappeared from radar screens entirely.

In 1958, the CIA requested funding for a reconnaissance aircraft, to replace U-2

Lockheed U-2

spy planes in which Lockheed

Lockheed Corporation

The Lockheed Corporation was an American aerospace company. Lockheed was founded in 1912 and later merged with Martin Marietta to form Lockheed Martin in 1995.-Origins:...

secured contractual rights to produce the aircraft. "Kelly" Johnson

Clarence Johnson

Clarence Leonard "Kelly" Johnson was an aircraft engineer and aeronautical innovator. As a member and first team leader of the Lockheed Skunk Works, Johnson worked for more than four decades and is said to have been an "organizing genius"...

and his team at Lockheed's Skunk Works

Skunk works

Skunk Works is an official alias for Lockheed Martin’s Advanced Development Programs , formerly called Lockheed Advanced Development Projects. Skunk Works is responsible for a number of famous aircraft designs, including the U-2, the SR-71 Blackbird, the F-117 Nighthawk, and the F-22 Raptor...

were assigned to produce the A-12 or OXCART the first of the former top secret classified Blackbird series which operated at high altitude of 70,000 to 80,000 ft and speed of Mach

Mach number

Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...

3.2 to avoid radar detection. Radar absorbent material had already been introduced on U-2 spy planes, and various plane shapes had been developed in earlier prototypes named A1 to A11 to reduce its detection from radar. Later in 1964, using prior models, an optimal plane shape taking into account compactness was developed where another "Blackbird", the SR-71

SR-71 Blackbird

The Lockheed SR-71 "Blackbird" was an advanced, long-range, Mach 3+ strategic reconnaissance aircraft. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed Skunk Works. Clarence "Kelly" Johnson was responsible for many of the...

, was produced, surpassing prior models in both altitude of 90,000 ft and speed of Mach

Mach number

3.3. The Lockheed SR-71 included a number of stealthy features, notably its canted vertical stabilizers, the use of composite materials in key locations, and the overall finish in radar absorbing paint.

During 1970s, the U.S. Department of Defence then launched a project called Have Blue to develop a stealth fighter. Bidding between both Lockheed and Northrop

Northrop Corporation

Northrop Corporation was a leading United States aircraft manufacturer from its formation in 1939 until its merger with Grumman to form Northrop Grumman in 1994. The company is known for its development of the flying wing design, although only a few of these have entered service.-History:Jack...

for the tender was fierce to secure the multi-billion dollar contract. Lockheed incorporated in its program paper written by a Soviet/Russian

Russians

The Russian people are an East Slavic ethnic group native to Russia, speaking the Russian language and primarily living in Russia and neighboring countries....

physicist Pyotr Ufimtsev

Pyotr Ufimtsev

Pyotr Yakovlevich Ufimtsev is a Soviet/Russian physicist and mathematician, considered the seminal force behind modern stealth aircraft technology...

in 1962 titled Method of Edge Waves in the Physical Theory of Diffraction, Soviet Radio, Moscow, 1962. In 1971 this book was translated into English with the same title by U.S. Air Force, Foreign Technology Division (National Air Intelligence Center ), Wright-Patterson AFB, OH, 1971. Technical Report AD 733203, Defense Technical Information Center of USA, Cameron Station, Alexandria, VA, 22304-6145, USA. This theory played a critical role in the design of American stealth-aircraft F-117 and B-2. The paper was able to find whether a plane's shape design would minimise its detection by radar or its radar cross-section (RCS) using a series of equations could be used to evaluate the radar cross section of any shape. Lockheed used it to design a shape they called the Hopeless Diamond, securing contractual rights to mass produce the F-117 Nighthawk

F-117 Nighthawk

The Lockheed F-117 Nighthawk was a single-seat, twin-engine stealth ground-attack aircraft formerly operated by the United States Air Force . The F-117A's first flight was in 1981, and it achieved initial operating capability status in October 1983...

.

The F-117 project began with a model called "The Hopeless Diamond" (a wordplay on the Hope Diamond

Hope Diamond

The Hope Diamond, also known as "Le bleu de France" or "Le Bijou du Roi", is a large, , deep-blue diamond, now housed in the Smithsonian Natural History Museum in Washington, D.C. It is blue to the naked eye because of trace amounts of boron within its crystal structure, but exhibits red...

) in 1975 due to its bizarre appearance. In 1977 Lockheed produced two 60% scale models under the Have Blue contract. The Have Blue program was a stealth technology demonstrator that lasted from 1976 to 1979. The success of Have Blue lead the Air Force to create the Senior Trend program which developed the F-117.

Principles

Stealth technology (or LO for "low observability") is not a single technology. It is a combination of technologies that attempt to greatly reduce the distances at which a person or vehicle can be detected; in particular radar cross section reductions, but also acoustic

Acoustic signature

Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

, thermal, and other aspects:

Radar cross-section (RCS) reductions

Almost since the invention of radar

Radar

, various methods have been tried to minimize detection. Rapid development of radar during WWII led to equally rapid development of numerous counter radar measures during the period; a notable example of this was the use of chaff

Chaff (radar countermeasure)

Chaff, originally called Window by the British, and Düppel by the Second World War era German Luftwaffe , is a radar countermeasure in which aircraft or other targets spread a cloud of small, thin pieces of aluminium, metallized glass fibre or plastic, which either appears as a cluster of secondary...

.

The term "stealth" in reference to reduced radar signature aircraft became popular during the late eighties when the Lockheed Martin F-117 stealth fighter

F-117 Nighthawk

became widely known. The first large scale (and public) use of the F-117 was during the Gulf War

Gulf War

The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

in 1991. However, F-117A stealth fighters were used for the first time in combat during Operation Just Cause, the United States invasion of Panama

United States invasion of Panama

The United States Invasion of Panama, code-named Operation Just Cause, was the invasion of Panama by the United States in December 1989. It occurred during the administration of U.S. President George H. W...

in 1989. Increased awareness of stealth vehicles and the technologies behind them is prompting the development of means to detect stealth vehicles, such as passive radar

Passive radar

Passive radar systems encompass a class of radar systems that detect and track objects by processing reflections from non-cooperative sources of illumination in the environment, such as commercial broadcast and communications signals...

arrays and low-frequency radar

Low-frequency radar

Low-frequency radar uses frequencies lower than 1 GHz, as opposed to the usual radar bands, which range from 2 Ghz and up,and the maximum is 40 Ghz.The radar cross section of any target depends on the radar transmitted frequency...

s. Many countries nevertheless continue to develop low-RCS vehicles because they offer advantages in detection range reduction and amplify the effectiveness of on-board systems against active radar guidance threats.

Vehicle shape

The possibility of designing aircraft in such a manner as to reduce their radar cross-section was recognized in the late 1930s, when the first radar tracking systems were employed, and it has been known since at least the 1960s that aircraft shape makes a significant difference in detectability. The Avro Vulcan

Avro Vulcan

, a British bomber

Bomber

A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...

of the 1960s, had a remarkably small appearance on radar despite its large size, and occasionally disappeared from radar screens entirely. It is now known that it had a fortuitously stealthy shape apart from the vertical element of the tail. In contrast, the Tupolev 95

Tupolev Tu-95

The Tupolev Tu-95 is a large, four-engine turboprop-powered strategic bomber and missile platform. First flown in 1952, the Tu-95 entered service with the former Soviet Union in 1956 and is expected to serve the Russian Air Force until at least 2040...

Russian long range bomber (NATO reporting name

NATO reporting name

NATO reporting names are classified code names for military equipment of the Eastern Bloc...

'Bear') appeared especially well on radar. It is now known that propeller

Propeller (aircraft)

Aircraft propellers or airscrews convert rotary motion from piston engines or turboprops to provide propulsive force. They may be fixed or variable pitch. Early aircraft propellers were carved by hand from solid or laminated wood with later propellers being constructed from metal...

s and jet turbine blades produce a bright radar image; the Bear had four pairs of large (5.6 meter diameter) contra-rotating propellers

Contra-rotating propellers

Aircraft equipped with contra-rotating propellers, also referred to as coaxial contra-rotating propellers, apply the maximum power of usually a single piston or turboprop engine to drive two propellers in contra-rotation...

.

Another important factor is internal construction. Some stealth aircraft have skin that is radar transparent or absorbing, behind which are structures termed re-entrant triangles. Radar waves penetrating the skin get trapped in these structures, reflecting off the internal faces and losing energy. This method was first used on the Blackbird series (A-12 / YF-12A / SR-71).

The most efficient way to reflect radar waves back to the emitting radar is with orthogonal metal plates, forming a corner reflector

Corner reflector

A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat surfaces, which reflects waves back directly towards the source, but shifted . Unlike a simple mirror, they work for a relatively wide-angle field of view. The three intersecting surfaces often have...

consisting of either a dihedral (two plates) or a trihedral (three orthogonal plates). This configuration occurs in the tail of a conventional aircraft, where the vertical and horizontal components of the tail are set at right angles. Stealth aircraft such as the F-117 use a different arrangement, tilting the tail surfaces to reduce corner reflections formed between them. A more radical method is to eliminate the tail completely, as in the B-2 Spirit

B-2 Spirit

The Northrop Grumman B-2 Spirit is an American heavy bomber with low observable stealth technology designed to penetrate dense anti-aircraft defenses and deploy both conventional and nuclear weapons. The bomber has a crew of two and can drop up to eighty -class JDAM GPS-guided bombs, or sixteen ...

.

In addition to altering the tail, stealth design must bury the engines within the wing

Wing

A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

or fuselage

Fuselage

The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...

, or in some cases where stealth is applied to an extant aircraft, install baffles in the air intakes, so that the turbine blades are not visible to radar. A stealthy shape must be devoid of complex bumps or protrusions of any kind; meaning that weapons, fuel tanks, and other stores must not be carried externally. Any stealthy vehicle becomes un-stealthy when a door or hatch opens.

Planform

Planform

In aviation, a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing. Of all the myriad planforms used, they can typically be grouped into those used for low-speed flight, found on general aviation aircraft, and those used for high-speed flight, found on many military...

alignment is also often used in stealth designs. Planform alignment involves using a small number of surface orientations in the shape of the structure. For example, on the F-22A Raptor, the leading edges of the wing and the tail surfaces are set at the same angle. Careful inspection shows that many small structures, such as the air intake bypass doors and the air refueling aperture, also use the same angles. The effect of planform alignment is to return a radar signal in a very specific direction away from the radar emitter rather than returning a diffuse signal

Diffuse reflection

Diffuse reflection is the reflection of light from a surface such that an incident ray is reflected at many angles rather than at just one angle as in the case of specular reflection...

detectable at many angles.

Stealth airframe

Airframe

The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...

s sometimes display distinctive serrations on some exposed edges, such as the engine ports. The YF-23

YF-23 Black Widow II

The Northrop YF-23 or Northrop–McDonnell Douglas YF-23 was an American single-seat, twin-engine fighter aircraft designed for the United States Air Force . The design was a finalist in the USAF's Advanced Tactical Fighter competition, battling the Lockheed YF-22 for a production contract...

has such serrations on the exhaust ports. This is another example in the use of re-entrant triangles and planform alignment, this time on the external airframe.

Shaping requirements have strong negative influence on the aircraft's aerodynamic properties. The F-117 has poor aerodynamics, is inherently unstable

Relaxed stability

In aviation, relaxed stability is the tendency of an aircraft to change its attitude and angle of bank of its own accord. An aircraft with relaxed stability will oscillate in simple harmonic motion around a particular attitude at an increasing amplitude....

, and cannot be flown without a fly-by-wire control system.

Ships have also adopted similar methods. The Skjold class patrol boat

Skjold class patrol boat

The Skjold class patrol boats is a new class of superfast, large stealth missile craft, formerly known as MTBs . From 2009, the Royal Norwegian Navy officially label them as coastal corvettes because their seaworthiness is seen as comparable to corvettes. They are built at the Umoe Mandal yard...

was the first stealth ship

Stealth ship

A stealth ship is a 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...

to enter service, though the earlier Arleigh Burke class destroyer

Arleigh Burke class destroyer

The Arleigh Burke class of guided missile destroyers is the United States Navy's first class of destroyer built around the Aegis combat system and the SPY-1D multi-function phased array radar. The class is named for Admiral Arleigh "31-Knot" Burke, the most famous American destroyer officer of...

incorporated some signature-reduction features. Other examples are the French La Fayette class frigate

La Fayette class frigate

The La Fayette class units are light multi-mission frigates built by DCN and operated by French Marine Nationale...

, the German Sachsen class frigate

Sachsen class frigate

The F124 Sachsen class is Germany's latest class of highly advanced air-defense frigates. The design of the Sachsen class frigate is based on that of the F123 Brandenburg class but with enhanced stealth features intended to deceive any opponent's radar and acoustic sensors and incorporate also the...

s, the Swedish Visby class corvette

Visby class corvette

The Visby is the latest class of corvette to be adopted by the Royal Swedish Navy after the Göteborg and the Stockholm class corvettes. The ship's design heavily emphasizes "low visibility" or stealth technology. The first ship in the class is named after Visby, the main city on the island of Gotland...

, the USS San Antonio

USS San Antonio (LPD-17)

USS San Antonio , the lead ship of her class of amphibious transport dock or landing platform dock, is the first ship of the United States Navy to be named for the city of San Antonio, Texas...

amphibious transport dock

Amphibious transport dock

An amphibious transport dock, also called a landing platform/dock , is an amphibious warfare ship, a warship that embarks, transports, and lands elements of a landing force for expeditionary warfare missions. Several navies currently operate this kind of ship...

, and most modern warship

Warship

A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

designs.

Similarly, coating the cockpit canopy with a thin film

Thin film

A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....

transparent conductor (vapor-deposited

Physical vapor deposition

Physical vapor deposition is a variety of vacuum deposition and is a general term used to describe any of a variety of methods to deposit thin films by the condensation of a vaporized form of the desired film material onto various workpiece surfaces...

gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

or indium tin oxide

Indium tin oxide

Indium tin oxide is a solid solution of indium oxide and tin oxide , typically 90% In2O3, 10% SnO2 by weight. It is transparent and colorless in thin layers while in bulk form it is yellowish to grey...

) helps to reduce the aircraft's radar profile, because radar waves would normally enter the cockpit, reflect off objects (the inside of a cockpit has a complex shape, with a pilot helmet alone forming a sizeable return), and possibly return to the radar, but the conductive coating creates a controlled shape that deflects the incoming radar waves away from the radar. The coating is thin enough that it has no adverse effect on pilot vision.

Non-metallic airframe

Dielectric

A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...

composites

Composite material

Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...

are more transparent to radar, whereas electrically conductive materials such as metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

s and carbon fiber

Carbon fiber

Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...

s reflect electromagnetic energy incident on the material's surface. Composites may also contain ferrites

Ferrite (magnet)

Ferrites are chemical compounds consisting of ceramic materials with iron oxide as their principal component. Many of them are magnetic materials and they are used to make permanent magnets, ferrite cores for transformers, and in various other applications.Many ferrites are spinels with the...

to optimize the dielectric and magnetic properties of a material for its application.

Radar-absorbing material

Radar-absorbent material (RAM), often as paints, are used especially on the edges of metal surfaces. While the material and thickness of RAM coatings is classified, the material seeks to absorb radiated energy from a ground or air based radar station into the coating and convert it to heat rather than reflect it back.

Low-frequency radar

Shaping offers far fewer stealth advantages against low-frequency radar

Low-frequency radar

. If the radar wavelength

Wavelength

In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...

is roughly twice the size of the target, a half-wave resonance

Resonance

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

effect can still generate a significant return. However, low-frequency radar is limited by lack of available frequencies-many are heavily used by other systems, by lack of accuracy of the diffraction-limited systems given their long wavelengths, and by the radar's size, making it difficult to transport. A long-wave radar may detect a target and roughly locate it, but not provide enough information to identify it, target it with weapons, or even to guide a fighter to it. Noise poses another problem, but that can be efficiently addressed using modern computer technology; Chinese "Nantsin" radar and many older Soviet-made long-range radars were modified this way. It has been said that "there's nothing invisible in the radar frequency range below 2 GHz".

Multiple emitters

Much of the stealth comes from reflecting radar emissions in directions different than a direct return. Thus, detection can be better achieved if emitters are separate from receivers. One emitter separate from one receiver is termed bistatic radar

Bistatic radar

Bistatic radar is the name given to a radar system which comprises a transmitter and receiver which are separated by a distance that is comparable to the expected target distance. Conversely, a radar in which the transmitter and receiver are collocated is called a monostatic radar...

; one or more emitters separate from more than one receiver is termed multistatic radar

Multistatic radar

A multistatic radar system contains multiple spatially diverse monostatic radar or bistatic radar components with a shared area of coverage. An important distinction systems based on these individual radar geometries is the added requirement for some level of data fusion to take place between...

. Proposals exist to use reflections from emitters such as civilian radio transmitter

Transmitter

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

s, including cellular telephone radio towers

Cell site

A cell site is a term used to describe a site where antennas and electronic communications equipment are placed, usually on a radio mast, tower or other high place, to create a cell in a cellular network...

Moore's law

By Moore's law

Moore's Law

Moore's law describes a long-term trend in the history of computing hardware: the number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years....

the processing power behind radar systems is rising over time. This will erode the ability of physical stealth to hide vehicles.

Ship's wakes and spray

Synthetic Aperture sidescan radars can be used to detect the location and heading of ships from their wake patterns. These may be detectable from orbit. When a ship moves through a seaway it throws up a cloud of spray which can be detected by radar.

Acoustics

Acoustic stealth plays a primary role in submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

stealth as well as for ground vehicles. Submarines use extensive rubber mountings to isolate and avoid mechanical noises that could reveal locations to underwater passive sonar arrays.

Early stealth observation aircraft

Surveillance aircraft

A surveillance aircraft is an aircraft used for surveillance — collecting information over time. They are operated by military forces and other government agencies in roles such as intelligence gathering, battlefield surveillance, airspace surveillance, observation , border patrol and fishery...

used slow-turning propeller

Propeller (aircraft)

s to avoid being heard by enemy troops below. Stealth aircraft that stay subsonic can avoid being tracked by sonic boom

Sonic boom

A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion...

. The presence of supersonic and jet-powered stealth aircraft such as the SR-71 Blackbird

SR-71 Blackbird

indicates that acoustic signature

Acoustic signature

Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...

is not always a major driver in aircraft design, although the Blackbird relied more on its extremely high speed and altitude.

Visibility

The simplest stealth technology is simply camouflage

Camouflage

; the use of paint or other materials to color and break up the lines of the vehicle or person.

Most stealth aircraft use matte paint and dark colors, and operate only at night. Lately, interest in daylight Stealth (especially by the USAF) has emphasized the use of gray paint in disruptive schemes

Dazzle camouflage

Dazzle camouflage, also known as Razzle Dazzle or Dazzle painting, was a camouflage paint scheme used on ships, extensively during World War I and to a lesser extent in World War II...

, and it is assumed that Yehudi lights

Yehudi lights

could be used in the future to mask shadows in the airframe

Airframe

The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...

(in daylight, against the clear background of the sky, dark tones are easier to detect than light ones) or as a sort of active camouflage

Active camouflage

Active camouflage or adaptive camouflage, is a group of camouflage technologies which allow an object to blend into its surroundings by use of panels or coatings capable of altering their appearance, color, luminance and reflective properties...

. The original B-2 design had wing tanks for a contrail

Contrail

Contrails or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines...

-inhibiting chemical, alleged by some to be chlorofluorosulfonic acid, but this was replaced in the final design with a contrail sensor from Ophir that alerts the pilot when he should change altitude and mission planning also considers altitudes where the probability of their formation is minimized.

Infrared

An exhaust plume contributes a significant infrared signature

Infrared signature

The term infrared signature is used by defense scientists and the military to describe the appearance of objects to infrared sensors. An infrared signature depends on many factors, including the shape and size of the object, temperature and emissivity, reflection of external sources from the...

. One means to reduce IR signature is to have a non-circular tail pipe

Exhaust system

An exhaust system is usually tubing used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes...

(a slit shape) to minimize the exhaust cross-sectional volume and maximize the mixing of hot exhaust with cool ambient air. Often, cool air is deliberately injected into the exhaust flow to boost this process. Sometimes, the jet exhaust is vented above the wing surface to shield it from observers below, as in the B-2 Spirit

B-2 Spirit

, and the unstealthy A-10 Thunderbolt II

A-10 Thunderbolt II

The Fairchild Republic A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support for ground forces by attacking tanks,...

. To achieve infrared stealth, the exhaust gas is cooled to the temperatures where the brightest wavelengths it radiates

Wien's displacement law

Wien's displacement law states that the wavelength distribution of thermal radiation from a black body at any temperature has essentially the same shape as the distribution at any other temperature, except that each wavelength is displaced on the graph...

are absorbed by atmospheric carbon dioxide and water vapor, dramatically reducing the infrared visibility of the exhaust plume. http://www.ausairpower.net/optical-warfare.html Another way to reduce the exhaust temperature is to circulate coolant

Coolant

A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...

fluids such as fuel inside the exhaust pipe, where the fuel tanks serve as heat sink

Heat sink

A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...

s cooled by the flow of air along the wings.

Ground combat includes the use of both active and passive infrared sensors and so the USMC ground combat uniform requirements document specifies infrared reflective quality standards.

Reducing radio frequency (RF) emissions

In addition to reducing infrared and acoustic emissions, a stealth vehicle must avoid radiating any other detectable energy, such as from onboard radars, communications systems, or RF leakage

TEMPEST

TEMPEST is a codename referring to investigations and studies of compromising emission . Compromising emanations are defined as unintentional intelligence-bearing signals which, if intercepted and analyzed, may disclose the information transmitted, received, handled, or otherwise processed by any...

from electronics enclosures. The F-117 uses passive infrared and low light level television sensor systems to aim its weapons and the F-22 Raptor

F-22 Raptor

The Lockheed Martin/Boeing F-22 Raptor is a single-seat, twin-engine fifth-generation supermaneuverable fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack, electronic warfare, and signals...

has an advanced LPI radar

Low probability of intercept

A low-probability-of-intercept radar is designed to be difficult to detect by passive radar detection equipment while it is searching for a target or engaged in target tracking...

which can illuminate enemy aircraft without triggering a radar warning receiver

Radar warning receiver

Radar warning receiver systems detect the radio emissions of radar systems. Their primary purpose is to issue a warning when a radar signal that might be a threat is detected. The warning can then be used, manually or automatically, to evade the detected threat...

response.

Measuring

The size of a target's image on radar is measured by the radar cross section

Radar cross section

Radar cross section is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.An object reflects a limited amount of radar energy...

or RCS, often represented by the symbol σ and expressed in square meters. This does not equal geometric area. A perfectly conducting sphere of projected cross sectional area 1 m² (i.e. a diameter of 1.13 m) will have an RCS of 1 m². Note that for radar wavelengths much less than the diameter of the sphere, RCS is independent of frequency. Conversely, a square flat plate of area 1 m² will have an RCS of σ = 4π A² / λ² (where A=area, λ=wavelength), or 13,982 m² at 10 GHz if the radar is perpendicular to the flat surface. At off-normal incident angles, energy is reflected away from the receiver, reducing the RCS. Modern stealth aircraft are said to have an RCS comparable with small birds or large insects, though this varies widely depending on aircraft and radar.

If the RCS was directly related to the target's cross-sectional area, the only way to reduce it would be to make the physical profile smaller. Rather, by reflecting much of the radiation away or by absorbing it, the target achieves a smaller radar cross section.

Tactics

Stealthy strike aircraft such as the F-117, designed by Lockheed Martin

Lockheed Martin

Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....

's famous Skunk Works

Skunk works

, are usually used against heavily defended enemy sites such as Command and Control

Command and Control (military)

Command and control, or C2, in a military organization can be defined as the exercise of authority and direction by a properly designated commanding officer over assigned and attached forces in the accomplishment of the mission...

centers or surface-to-air missile

Surface-to-air missile

A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

(SAM) batteries. Enemy radar will cover the airspace around these sites with overlapping coverage, making undetected entry by conventional aircraft nearly impossible. Stealthy aircraft can also be detected, but only at short ranges around the radars, so that for a stealthy aircraft there are substantial gaps in the radar coverage. Thus a stealthy aircraft flying an appropriate route can remain undetected by radar. Many ground-based radars exploit Doppler

Doppler radar

A Doppler radar is a specialized radar that makes use of the Doppler effect to produce velocity data about objects at a distance. It does this by beaming a microwave signal towards a desired target and listening for its reflection, then analyzing how the frequency of the returned signal has been...

filter to improve sensitivity

Clutter (radar)

Clutter is a term used for unwanted echoes in electronic systems, particularly in reference to radars. Such echoes are typically returned from ground, sea, rain, animals/insects, chaff and atmospheric turbulences, and can cause serious performance issues with radar systems.- Backscatter coefficient...

to objects having a radial velocity component with respect to the radar. Mission planners use their knowledge of enemy radar locations and the RCS pattern of the aircraft to design a flight path that minimizes radial speed while presenting the lowest-RCS aspects of the aircraft to the threat radar. To be able to fly these "safe" routes, it is necessary to understand an enemy's radar coverage (see Electronic Intelligence). Airborne or mobile radar systems such as AWACS can complicate tactical strategy for stealth operation.

Research

Negative index metamaterials

Negative index metamaterials or negative index materials are artificial structures where the refractive index has a negative value over some frequency range. This does not occur in any known natural materials, and thus is only achievable with engineered structures known as metamaterials...

are artificial structures which refractive index has a negative value for some frequency range, such as in microwave, infrared, or possibly optical. These offer another way to reduce detectability, and may provide electromagnetic near-invisibility in designed wavelengths.

Plasma stealth

Plasma stealth

Plasma stealth is a proposed process to use ionized gas to reduce the radar cross section of an aircraft. Interactions between electromagnetic radiation and ionized gas have been extensively studied for many purposes, including concealing aircraft from radar as stealth technology...

is a phenomenon proposed to use ionized gas (plasma

Plasma (physics)

In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

) to reduce RCS of vehicles. Interactions between electromagnetic radiation

Electromagnetic radiation

Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

and ionized gas have been studied extensively for many purposes, including concealing vehicles from radar. Various methods might form a layer or cloud of plasma around a vehicle to deflect or absorb radar, from simpler electrostatic to RF

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

more complex laser discharges, but these may be difficult in practice.

Several technology research and development efforts exist to integrate the functions of aircraft flight control systems such as aileron

Aileron

Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...

s, elevators

Elevator (aircraft)

Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...

, elevon

Elevon

Elevons are aircraft control surfaces that combine the functions of the elevator and the aileron , hence the name. They are frequently used on tailless aircraft such as flying wings. An elevon that is not part of the main wing, but instead is a separate tail surface, is a stabilator...

s, flap

Flap (aircraft)

Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...

s, and flaperon

Flaperon

A flaperon is a type of aircraft control surface that combines aspects of both flaps and ailerons. In addition to controlling the roll or bank of an aircraft as do conventional ailerons, both flaperons can be lowered together to function similarly to a dedicated set of flaps...

s into wings to perform the aerodynamic purpose with the advantages of lower RCS for stealth via simpler geometries and lower complexity (mechanically simpler, fewer or no moving parts or surfaces, less maintenance), and lower mass, cost (up to 50% less), drag (up to 15% less during use) and, inertia

Inertia

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

(for faster, stronger control response to change vehicle orientation to reduce detection). Two promising approaches are flexible wings, and fluidics.

In flexible wings, much or all of a wing surface can change shape in flight to deflect air flow. The X-53 Active Aeroelastic Wing is a NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

effort. The Adaptive Compliant Wing

Adaptive Compliant Wing

The Adaptive Compliant Wing is a wing design developed by FlexSys, Inc., which is flexible so that aspects of its shape can be changed in flight....

is a military and commercial effort.

In fluidics

Fluidics

Fluidics or Fluidic logic is the use of a fluid to perform analog or digital operations similar to those performed with electronics.The physical basis of fluidics is pneumatics and hydraulics, based on the theoretical foundation of fluid dynamics...

, fluid injection is being researched for use in aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

to control direction, in two ways: circulation control and thrust vectoring. In both, larger more complex mechanical parts are replaced by smaller, simpler fluidic systems, in which larger forces in fluids are diverted by smaller jets or flows of fluid intermittently, to change the direction of vehicles.

In circulation control, near the trailing edges of wings, aircraft flight control systems are replaced by slots which emit fluid flows.

In thrust vectoring

Thrust vectoring

Thrust vectoring, also thrust vector control or TVC, is the ability of an aircraft, rocket or other vehicle to manipulate the direction of the thrust from its engine or motor in order to control the attitude or angular velocity of the vehicle....

, in jet engine

Jet engine

A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...

nozzles, swiveling parts are replaced by slots which inject fluid flows into jets to divert thrust. Tests show that air forced into a jet engine exhaust stream can deflect thrust up to 15 degrees. The U.S. FAA has conducted a study about civilizing 3D military thrust vectoring to help jetliners avoid crashes. According to this study, 65% of all air crashes can be prevented by deploying thrust vectoring means.

Fully stealth types

Braunschweig class corvette
Braunschweig class corvette
The K130 Braunschweig class is Germany's newest class of ocean-going corvettes. They supplement the Gepard class fast attack craft that are currently used.-Technical details:...
De Zeven Provinciën class frigate
De Zeven Provinciën class frigate
The De Zeven Provinciën class frigates are highly advanced air-defence and command frigates in service with the Koninklijke Marine . This class of ships is also known as LCF...
Future Dutch Navy offshore patrol vessels
Future Dutch Navy offshore patrol vessels
The Holland class Offshore Patrol Vessels are new patrol boats under construction for the Royal Netherlands Navy. They are designed to fulfil patrol and intervention tasks against lightly armed opponents, such as pirates and smugglers.-History:...
Rotterdam class amphibious transport dock
F125 class frigate
F125 class frigate
F125 is the project name for the Type 125 Baden-Württemberg class of frigates, currently in development for the German Navy by ARGE F125, a joint-venture of Thyssen-Krupp and Lürssen...
Type 45 destroyer
Type 45 destroyer
The United Kingdom's Type 45 destroyer is an air defence destroyer programme of the Royal Navy which will replace its Type 42 destroyers. The first ship in the class, HMS Daring, was launched on 1 February 2006 and commissioned on 23 July 2009. The ships are now built by BAE Systems Surface Ships...
Formidable class frigate
Formidable class frigate
The Formidable class multi-role stealth frigates are the latest surface platforms to enter into service with the Republic of Singapore Navy, and are multi-mission derivatives of the French Navy’s La Fayette class frigate. The frigates are key information nodes and fighting units, and are described...
Hamina class missile boatHamina class missile boat
The Hamina class missile boat is a 4-strong class of fast attack craft of the Finnish Navy. Technically they are classified as "missile fast attack craft", ohjusvene, literally "missile boat" in Finnish.-History:...

Kolkata Class Destroyer
Kolkata class destroyer
The Kolkata class of guided-missile destroyers of the Indian Navy were conceptualized under Project 15A, and include land-attack capability as well as some signature reduction features. Three ships of the class are being built at Mazagon Dock Limited . The first vessel is expected to join the fleet...
Kedah class New Generation Patrol Vessels
La Fayette class frigate
La Fayette class frigate
The La Fayette class units are light multi-mission frigates built by DCN and operated by French Marine Nationale...
Littoral combat ship
Littoral combat ship
A Littoral Combat Ship is a type of relatively small surface vessel intended for operations in the littoral zone . It is "envisioned to be a networked, agile, stealthy surface combatant capable of defeating anti-access and asymmetric threats in the littorals." Two ship classes are the first...
Project 17A class frigate
Project 17A class frigate
The Project 17A is the follow on the Project 17 frigates for the Indian Navy. A total of seven ships will be built. The ships will be built at Mazagon Dock Limited and at GRSE. The Indian shipyards would start the construction of the first ship by 2011 after the process of upgradation of the...
Sachsen class frigate
Sachsen class frigate
The F124 Sachsen class is Germany's latest class of highly advanced air-defense frigates. The design of the Sachsen class frigate is based on that of the F123 Brandenburg class but with enhanced stealth features intended to deceive any opponent's radar and acoustic sensors and incorporate also the...
Sea Shadow (IX-529)
Sea Shadow (IX-529)
Sea Shadow is an experimental stealth ship built by Lockheed for the United States Navy to determine how a low radar profile might be achieved and to test high stability hull configurations which have been used in oceanographic ships....
Shivalik class frigate
Shivalik class frigate
The Shivalik class frigates or Project 17 class frigates are multi-role frigates with stealth features being built for the Indian Navy. They are the first warships being built in India with such features. The lead vessel of the class was commissioned on April 29, 2010.The Shivalik class will be the...
Skjold class patrol boat
Skjold class patrol boat
The Skjold class patrol boats is a new class of superfast, large stealth missile craft, formerly known as MTBs . From 2009, the Royal Norwegian Navy officially label them as coastal corvettes because their seaworthiness is seen as comparable to corvettes. They are built at the Umoe Mandal yard...
Visby class corvette
Visby class corvette
The Visby is the latest class of corvette to be adopted by the Royal Swedish Navy after the Göteborg and the Stockholm class corvettes. The ship's design heavily emphasizes "low visibility" or stealth technology. The first ship in the class is named after Visby, the main city on the island of Gotland...
Type 052C destroyer
Type 054A frigate
Type 054A frigate
The Type 054A frigate is a Chinese multi-role warship that entered service with the People's Liberation Army Navy in 2007...
Zumwalt class destroyer
Zumwalt class destroyer
The Zumwalt class destroyer is a planned class of United States Navy destroyers, designed as multi-mission ships with a focus on land attack. The class is a scaled-back project that emerged after funding cuts to the larger DD-21 vessel program. The program was previously known as the "DD"...
Houbei class missile boat
Houbei class missile boat
The Houbei class missile boat is a class in the People's Liberation Army Navy. The first boat was launched in April 2004 by the Qiuxin Shipbuilding Factory at Shanghai. The boats incorporate stealth features and wave-piercing catamaran hulls...
Milgem
Milgem
The MİLGEM project, from the Turkish words Milli Gemi , is a Turkish national warship program, the purpose of which is to build a modern littoral combat warship with indigenous anti-submarine warfare and high-seas patrol capabilities, extensively using the principles of stealth technology in its...

s
Tartarstan/Gepard class frigate
Tartarstan/Gepard class frigate
The Gepard class frigates were intended as a successor to the earlier Koni, Grisha, and Parchim-class corvettes. The first unit of the class, Yastreb , was laid down at the Zelenodol'sk Zavod shipyard at Tatarstan in 1991. It was launched in July 1993, after which it began fitting out...
Project 21630 Buyan
Buyan class corvette
The Buyan class corvette was designed by Zelenodolsk Design and designated Project 21630 by the Russian Government. This is the newest corvette of the Russian Navy. The first ship of her class, the Astrakhan was commissioned on January 2006, and assigned to the Caspian Flotilla.In Aug 2010 some...
Project 20380 Steregushchiy
Admiral Grigorovich class frigate
Admiral Grigorovich class frigate
The Admiral Grigorovich class is the latest class of frigates ordered by the Russian Navy for the Black Sea Fleet. Three ships have been ordered so far to be built by the "Yantar" shipyard in Kaliningrad. The frigates are based on the Talwar-class frigate, six of which were ordered by the Indian...
Gorshkov class frigate
Admiral Sergei Gorshkov class frigate
The Admiral Gorshkov-class frigates, also known as Project 22350, are a class of frigate of the Russian Navy. They have been designed by the Severnoye Design Bureau, Saint Petersburg, the lead ship being named after Sergey Gorshkov.- Design :...
Project 21956
Project 21956
The Project 21956 multi-purpose destroyer represents the fourth generation of Russian surface fighting ships developed by the Severnoye Design Bureau.- Design :...

destroyer
FREMM multipurpose frigates
Horizon CNGF

Reduced RCS types

Gerald R. Ford class aircraft carrier
Arleigh Burke class destroyer
Arleigh Burke class destroyer
The Arleigh Burke class of guided missile destroyers is the United States Navy's first class of destroyer built around the Aegis combat system and the SPY-1D multi-function phased array radar. The class is named for Admiral Arleigh "31-Knot" Burke, the most famous American destroyer officer of...
San Antonio class amphibious transport dock
San Antonio class amphibious transport dock
The San Antonio class is the United States Navy's new primary class of amphibious transport dock in the beginning of the 21st century...
Atago class destroyer
Atago class destroyer
The is an improved version of the Japan Maritime Self-Defense Force 's Kongō class destroyers. It is a Japanese variant of the United States Navy Arleigh Burke-class destroyer ....
Sejong the Great destroyer
Neustrashimy class frigate
Neustrashimy Class frigate
Neustrashimy class frigates are the most modern large frigates in the Russian Navy. The Soviet designation is Project 1154 Yastreb .-Design:...

External links

Grant, Rebecca
Rebecca Grant (political expert)
Rebecca L. Grant is the Director of the General Billy Mitchell Institute for Airpower Studies at the Air Force Association and a contributing editor for their Air Force Magazine.She is also a senior fellow at the Lexington Institute. She earned her Ph.D...

, The Radar Game: Understanding Stealth and Aircraft Survivability, Iris Independent Research
The Advent, Evolution and New Horizons of United States Stealth Aircraft
What is Stealth Technology?
Stealth design used for military aircraft?
Stealth Satellites
Stealth in strike warfare
Stealth technology
The Paradigm Shift in Air Superiority (Stealth)
Stealth Technology
USAF Stealth Fighters briefing
Pyotr Ufimstev biography
Advancement of Plasma antennas in stealth

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

History

Principles

Radar cross-section (RCS) reductions

Vehicle shape

Non-metallic airframe

Radar-absorbing material

Low-frequency radar

Multiple emitters

Moore's law

Ship's wakes and spray

Acoustics

Visibility

Infrared

Reducing radio frequency (RF) emissions

Measuring

Tactics

Research

Fully stealth types

Reduced RCS types

See also

External links