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102-744: The AGM-158C LRASM ( Long Range Anti-Ship Missile ) is a stealth air launch anti-ship cruise missile developed for the United States Air Force and United States Navy by the Defense Advanced Research Projects Agency ( DARPA ). Derived from the AGM-158B JASSM-ER , the LRASM was intended to pioneer more sophisticated autonomous targeting capabilities than the U.S. Navy's current Harpoon anti-ship missile , which has been in service since 1977. In June 2009, DARPA awarded

204-560: A B-1B flying over the Point Mugu Sea Range. In May 2018 a second flight test, involving two LRASMs, was successfully completed. In December 2018, the LRASM was integrated on the USAF's B-1 Lancer , reaching initial operational capability . The missile achieved early operational capability on Navy Super Hornets in November 2019. In 2020, The US Navy began plans to integrate the LRASM on

306-466: A corner reflector 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

408-614: A radial velocity component relative 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 airborne early warning and control (AEW&C, AWACS) can complicate tactical strategy for stealth operation. After

510-451: A British bomber 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. Despite being designed before a low radar cross-section (RCS) and other stealth factors were ever a consideration, a Royal Aircraft Establishment technical note of 1957 stated that of all

612-546: A complex signal environment, and then calculates precise target locations for the missile control unit. On 17 September 2013, Lockheed launched an LRASM Boosted Test Vehicle (BTV) from a Mk 41 VLS canister. The company-funded test showed the LRASM, fitted with the Mk 114 rocket motor from the RUM-139 VL-ASROC , could ignite and penetrate the canister cover and perform a guided flight profile. In January 2014, Lockheed demonstrated that

714-508: A contract to Lockheed Martin for the two-phase LRASM demonstration program. In December 2013, DARPA publicized its intent to award a sole-source follow-on contract to Lockheed Martin for continued maturation of the LRASM subsystems and system design, which will be transitioned to the Navy. In March 2014, Raytheon / Kongsberg filed a joint protest with the U.S. Government Accountability Office (GAO) against DARPA's decision. In June 2014, GAO denied

816-413: A data-link, and passive electronic support measures (ESM) and radar warning receiver sensors. Artificial intelligence software combines these features to locate enemy ships and avoid neutral shipping in crowded areas. Automatic dissemination of emissions data is classified, located, and identified for path of attack; the data-link allows other assets to feed the missile a real-time electronic picture of

918-402: A digital glitch in the processing system. Stealth airframes sometimes display distinctive serrations on some exposed edges, such as the engine ports. The YF-23 has such serrations on the exhaust ports. This is another example in the parallel alignment of features, this time on the external airframe. The shaping requirements detracted greatly from the F-117 's aerodynamic properties. It

1020-476: A door or hatch opens. Parallel alignment of edges or even surfaces is also often used in stealth designs. The technique involves using a small number of edge orientations in the shape of the structure. For example, on the F-22A Raptor , the leading edges of the wing and the tail planes are set at the same angle. Other smaller structures, such as the air intake bypass doors and the air refueling aperture, also use

1122-472: A missile prototype was planned to fly in "early 2013" and the first canister launch was intended for "end 2014". On 1 October 2012, Lockheed received a contract modification to perform risk reduction enhancements in advance of the upcoming flight test of the air-launched LRASM-A version. On 5 March 2013, Lockheed received a contract to begin conducting air and surface-launch tests of the LRASM. On 3 June 2013, Lockheed successfully conducted "push through" tests of

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1224-422: A number of stealthy features including special fuel to reduce the signature of the exhaust plume, canted vertical stabilizers, the use of composite materials in key locations, and the overall finish in radar-absorbent paint. In 1960, the USAF reduced the radar cross-section of a Ryan Q-2C Firebee drone. This was achieved through specially designed screens over the air intake, and radiation-absorbent material on

1326-675: A part in the development of composite material and curvilinear surfaces, low observables, fly-by-wire, and other stealth technology innovations. The success of Have Blue led the Air Force to create the Senior Trend program which developed the F-117. In the early 21st century, the proliferation of stealth technology began outside of the United States. Both Russia and China tested their stealth aircraft in 2010. Russia manufactured 10 flyable prototypes of

1428-557: A person or vehicle can be detected; more so radar cross-section reductions , but also acoustic , thermal , and other aspects. Almost since the invention of radar , various methods have been tried to minimize detection. Rapid development of radar during World War II led to equally rapid development of numerous counter radar measures during the period; a notable example of this was the use of chaff . Modern methods include radar jamming and deception . The term stealth in reference to reduced radar signature aircraft became popular during

1530-447: A planned route to autonomous guidance. It autonomously detected its moving target, a 260 ft (79 m) unmanned ship out of three in the target area, and hit it in the desired location with an inert warhead. The purpose of the test was to stress the sensor suite, which detected all the targets and only engaged the one it was told to. Two more flight tests were planned the year, involving different altitudes, ranges, and geometries in

1632-465: A primary role for submarines and ground vehicles. Submarines use extensive rubber mountings to isolate, damp, and avoid mechanical noises that can reveal locations to underwater passive sonar arrays. Early stealth observation aircraft used slow-turning propellers to avoid being heard by enemy troops below. Stealth aircraft that stay subsonic can avoid being tracked by sonic boom . The presence of supersonic and jet-powered stealth aircraft such as

1734-439: A production-representative, tactical configuration. The missile was dropped from a B-1B Lancer, navigated through all planned waypoints, transitioned to mid-course guidance and flew toward a moving maritime target using inputs from its onboard sensor, then descended to low altitude for final approach, positively identifying and impacting the target. The weapon was successfully fired against multiple targets on 13 December 2017, by

1836-426: A simulated LRASM on the Mk 41 Vertical Launch System (VLS). Four tests verified the LRASM can break the canister's forward cover without damaging the missile. On 11 July 2013, Lockheed reported successful completion of captive-carry testing of the LRASM on a B-1B . On 27 August 2013, Lockheed conducted the first flight test of the LRASM, launched from a B-1B . Halfway to its target, the missile switched from following

1938-487: 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. Ships have also adopted similar methods. Though the earlier Arleigh Burke-class destroyer incorporated some signature-reduction features. the Norwegian Skjold-class corvette

2040-439: A square flat plate of area 1 m will have an RCS of σ=4π A / λ (where A =area, λ =wavelength), or 13,982 m 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

2142-477: A stealth vehicle must avoid radiating any other detectable energy, such as from onboard radars, communications systems, or RF leakage 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 has an advanced LPI radar which can illuminate enemy aircraft without triggering a radar warning receiver response. The size of

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2244-420: A target's image on radar is measured by the radar cross section (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 m (i.e. a diameter of 1.13 m) will have an RCS of 1 m . Note that for radar wavelengths much less than the diameter of the sphere, RCS is independent of frequency. Conversely,

2346-417: Is inherently unstable , and cannot be flown without a fly-by-wire control system . Similarly, coating the cockpit canopy with a thin film transparent conductor ( vapor-deposited gold or indium tin oxide ) 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

2448-543: Is a phenomenon proposed to use ionized gas, termed a plasma , to reduce RCS of vehicles. Interactions between electromagnetic radiation 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 radio frequency (RF) more complex laser discharges, but these may be difficult in practice. Several technology research and development efforts exist to integrate

2550-507: Is a sub-discipline of military tactics and passive and active electronic countermeasures . The term covers a range of methods used to make personnel, aircraft , ships , submarines , missiles , satellites , and ground vehicles less visible (ideally invisible ) to radar , infrared , sonar and other detection methods. It corresponds to military camouflage for these parts of the electromagnetic spectrum (i.e., multi-spectral camouflage ). Development of modern stealth technologies in

2652-414: Is assumed that Yehudi lights could be used in the future to hide the airframe (against the background of the sky, including at night, aircraft of any colour appear dark ) or as a sort of active camouflage. The original B-2 design had wing tanks for a contrail -inhibiting chemical, alleged by some to be chlorofluorosulfonic acid, but this was replaced in the final design with a contrail sensor that alerts

2754-453: Is based on the AGM-158B JASSM-ER , but incorporates a multi-mode passive RF , a new weapon data-link and altimeter, and an uprated power system. It can be directed to attack enemy ships by its launch platform, receive updates via its datalink , or use onboard sensors to find its target. LRASM will fly towards its target at medium altitude then drop to low altitude for a sea skimming approach to counter missile defenses . The AGM-158B JASSM-ER

2856-414: Is essential, and mistakes can lead to detectability enhancement rather than the desired reduction. An exhaust plume contributes a significant infrared signature. One means to reduce IR signature is to have a non-circular tail pipe (a slit shape) to minimize the exhaust cross sectional area and maximize the mixing of hot exhaust with cool ambient air (see Lockheed F-117 Nighthawk , rectangular nozzles on

2958-516: Is expected the LRASM will compete against the joint Kongsberg / Raytheon offering of the Joint Strike Missile for air-launch needs and an upgraded Raytheon Tomahawk cruise missile for surface-launch needs. In August 2015, the missile was officially designated AGM-158C . Unlike current anti-ship missiles, the LRASM is expected to be capable of conducting autonomous targeting, relying on on-board targeting systems to independently acquire

3060-460: Is proportional to the fourth root of RCS; thus, reducing detection range by a factor of 10 requires a reduction of RCS by a factor of 10,000. 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 ,

3162-477: Is radar transparent or absorbing, behind which are structures termed reentrant 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 , Lockheed SR-71 Blackbird . The most efficient way to reflect radar waves back to the emitting radar is with orthogonal metal plates, forming

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3264-516: Is related to the type of radar or the type of vehicle that carries it, often with a distinction made between ground-based radars and airborne radars. The typical airborne RWR system consists of multiple wideband antennas placed around the aircraft which receive the radar signals. The receiver periodically scans across the frequency band and determines various parameters of the received signals, like frequency, signal shape, direction of arrival, pulse repetition frequency , etc. By using these measurements,

3366-456: Is to omit the tail, as in the B-2 Spirit . The B-2's clean, low-drag flying wing configuration gives it exceptional range and reduces its radar profile. The flying wing design most closely resembles a so-called infinite flat plate (as vertical control surfaces dramatically increase RCS), the perfect stealth shape, as it would have no angles to reflect back radar waves. In addition to altering

3468-571: Is to use metasurfaces which can redirect scattered waves without altering the geometry of a target. Such metasurfaces can primarily be classified in two categories: (i) checkerboard metasurfaces, (ii) gradient index metasurfaces. Similarly, negative index metamaterials are artificial structures for 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

3570-602: The Boeing P-8 Poseidon . In February 2021, U.S. Navy and Air Force awarded a $ 414 million contract to Lockheed Martin for continued production of the air-launched variant of LRASM, now operational on the U.S. Navy F/A-18E/F and U.S. Air Force B-1B. In 2015, Sweden publicly expressed interest in the LRASM in response to concerns of Russian actions in Eastern Europe . The United Kingdom , Singapore , Canada , Australia and Japan have also expressed interest in

3672-524: The F/A-18E/F Super Hornet and B-1B Lancer , which has the capacity to carry 24 LRASMs. In 2020, the U.S. Navy began the process of integrating the LRASM onto the P-8 Poseidon maritime patrol aircraft, to be completed by 2026. Some naval advisors have proposed increasing the LRASM's capabilities to serve dual functions as a ship-based land attack weapon in addition to anti-ship roles. By reducing

3774-527: The Lockheed Martin F-22 , and serrated nozzle flaps on the Lockheed Martin F-35 ). Often, cool air is deliberately injected into the exhaust flow to boost this process (see Ryan AQM-91 Firefly and Northrop B-2 Spirit ). The Stefan–Boltzmann law shows how this results in less energy ( Thermal radiation in infrared spectrum) being released and thus reduces the heat signature. In some aircraft,

3876-463: The SR-71 Blackbird indicates that acoustic signature is not always a major driver in aircraft design, as the Blackbird relied more on its very high speed and altitude. One method to reduce helicopter rotor noise is modulated blade spacing . Standard rotor blades are evenly spaced, and produce greater noise at a given frequency and its harmonics . Using varied spacing between the blades spreads

3978-425: 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. Stealth aircraft attempt to minimize all radar reflections, but are specifically designed to avoid reflecting radar waves back in

4080-500: The 5th century BC, and by Frontinus in his work Strategemata in the 1st century AD. In England, irregular units of gamekeepers in the 17th century were the first to adopt drab colours (common in 16th century Irish units) as a form of camouflage , following examples from the continent. During World War I , the Germans experimented with the use of Cellon ( Cellulose acetate ), a transparent covering material, in an attempt to reduce

4182-515: The B-1 Lancer. For surface launches, LRASM will be fitted with a modified Mk 114 jettisonable rocket booster to give it enough power to reach altitude. Although priority development is on air and surface-launched variants, Lockheed is exploring the concept of a submarine-launched variant, and deployment from a topside canister launcher for smaller ships. As part of OASUW Increment 1, the LRASM will be used only as an air-launched missile to be deployed from

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4284-688: The Harpoon and to prioritize defeating enemy warships, which has been neglected since the end of the Cold War but taken on importance with the modernization of the People's Liberation Army Navy . In March 2014, the Navy said it will hold a competition for the Offensive Anti-Surface Warfare (OASuW)/Increment 2 anti-ship missile as a follow-on to LRASM to enter service in 2024. The OASuW Increment 2 competition will be completely open and start by FY 2017. It

4386-689: The Kriegsmarine on submarines in World War II. Tests showed they were effective in reducing radar signatures at both short (centimetres) and long (1.5 metre) wavelengths. In 1956, the CIA began attempts to reduce the radar cross-section (RCS) of the U-2 spyplane. Three systems were developed, Trapeze, a series of wires and ferrite beads around the planform of the aircraft, a covering material with PCB circuitry embedded in it, and radar-absorbent paint. These were deployed in

4488-524: The LRASM conducted its third successful flight test, conducted to evaluate low-altitude performance and obstacle avoidance. Dropped from a B-1B , the missile navigated a series of planned waypoints, then detected, tracked, and avoided an object deliberately placed in the flight pattern in the final portion of the flight to demonstrate obstacle-avoidance algorithms. In August 2015, the Navy began load and fit checks of an LRASM mass simulator vehicle on an F/A-18 Super Hornet. Initial airworthiness flight testing of

4590-472: The LRASM could be launched from a Mk 41 VLS with only modified software to existing shipboard equipment. On 12 November 2013, an LRASM scored a direct hit on a moving naval target on its second flight test. A B-1B bomber launched the missile, which navigated using planned waypoints that it received in-flight before transitioning to autonomous guidance. It used onboard sensors to select the target, descend in altitude, and successfully impact. On 4 February 2015,

4692-578: The LRASM simulator with the Super Hornet began on 3 November 2015, with the first flight occurring on 14 December, and load testing completed on 6 January 2016. In July 2016, Lockheed successfully conducted the third surface launch of the LRASM following two tests at the Navy's Desert Ship, firing it from the Navy's Self Defense Test Ship (formerly the USS ; Paul F. Foster ). Tied to a Tactical Tomahawk Weapon Control System (TTWCS) for guidance and boosted by

4794-427: The Mk 114 motor, it flew a planned, low-altitude profile to its pre-determined endpoint. While the missile is currently planned to be exclusively air-launched, future requirements for employment across several launch platforms led to investment in risk-reduction for the future competition. On 4 April 2017, Lockheed announced the first successful release of the LRASM from an F/A-18 Super Hornet. On 26 July 2017, Lockheed

4896-554: 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. Stealthy strike aircraft such as the Lockheed F-117 Nighthawk , are usually used against heavily defended enemy sites such as command and control centers or surface-to-air missile (SAM) batteries. Enemy radar will cover

4998-458: The RWR display. The pilot then can take evasive action to break the missile lock-on or dodge the missile . The pilot may even be able to visually acquire the missile after being alerted to the possible launch. What's more, if an actively guided missile is tracking the aircraft, the pilot can use the direction and distance display of the RWR to work out which evasive maneuvers to perform to outrun or dodge

5100-447: The RWR. Especially at high altitude (more than 30,000 feet AGL ), very few threats exist that don't emit radiation. As long as the pilot is careful to check for aircraft that might try to sneak up without radar, say with the assistance of AWACS or GCI , it should be able to steer clear of SAMs, fighter aircraft and high altitude, radar-directed AAA . SEAD and ELINT aircraft often have sensitive and sophisticated RWR equipment like

5202-463: The Su-57, while China produced two stealth aircraft, Chengdu J-20 and Shenyang FC-31 . In 2017, China became the second country in the world to field an operational stealth aircraft, challenging the United States and its Asian allies. Stealth technology (or LO for low observability ) is not one technology. It is a set of technologies, used in combinations, that can greatly reduce the distances at which

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5304-643: The U.S. Central Intelligence Agency requested funding for a reconnaissance aircraft to replace the existing U-2 spy planes, and Lockheed secured contractual rights to produce it. "Kelly" Johnson and his team at Lockheed's Skunk Works were assigned to produce the A-12 (or OXCART), which operated at high altitude of 70,000 to 80,000 ft (21,000 to 24,000 m) and speed of Mach 3.2 (2,400 mph; 3,800 km/h) to avoid radar detection. Various plane shapes designed to reduce radar detection were developed in earlier prototypes, named A-1 to A-11. The A-12 included

5406-415: The U.S. HTS ( HARM targeting system) pod which is able to find and classify threats which are much further away than those detected by a typical RWR, and may be able to overlay threat circles on a map in the aircraft's multi-function display (MFD), providing much better information for avoiding or engaging threats, and may even store information to be analyzed later or transmitted to the ground to help

5508-557: The U.S. Department of Defense launched project Lockheed Have Blue , with the aim of developing a stealth fighter. There was fierce bidding between Lockheed and Northrop to secure the multibillion-dollar contract. Lockheed incorporated into its bid a text written by the Soviet-Russian physicist Pyotr Ufimtsev from 1962, titled Method of Edge Waves in the Physical Theory of Diffraction , Soviet Radio, Moscow, 1962. In 1971, this book

5610-489: The United States began in 1958, where earlier attempts to prevent radar tracking of its U-2 spy planes during the Cold War by the Soviet Union had been unsuccessful. Designers turned to developing a specific shape for planes that tended to reduce detection by redirecting electromagnetic radiation waves from radars. Radiation-absorbent material was also tested and made to reduce or block radar signals that reflect off

5712-577: The Vulcan's shape as acting to reduce the RCS. In contrast, the Tupolev 95 Russian long-range bomber ( NATO reporting name 'Bear') was conspicuous on radar. It is now known that propellers and jet turbine blades produce a bright radar image; the Bear has four pairs of large 18-foot (5.6 m) diameter contra-rotating propellers . Another important factor is internal construction. Some stealth aircraft have skin that

5814-423: The aircraft so far studied, the Vulcan appeared by far the simplest radar echoing object, due to its shape: only one or two components contributing significantly to the echo at any aspect (one of them being the vertical stabilizer , which is especially relevant for side aspect RCS), compared with three or more on most other types. While writing about radar systems, authors Simon Kingsley and Shaun Quegan singled out

5916-652: 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; 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. Even if a stealth aircraft is detected, fire-control radars operating in C , X and Ku bands cannot paint (for missile guidance) low observable (LO) jets except at very close ranges. Many ground-based radars exploit Doppler filter to improve sensitivity to objects having

6018-407: The coating and convert it to heat rather than reflect it back. Current technologies include dielectric composites and metal fibers containing ferrite isotopes. Ceramic composite coating is a new type of material systems which can sustain at higher temperatures with better sand erosion resistance and thermal resistance. Paint comprises depositing pyramid-like colonies on the reflecting superficies with

6120-440: The commanders plan future missions. The RWR can be an important tool for evading threats if avoidance has failed. For example, if a SAM system or enemy fighter aircraft has fired a missile (for example, a SARH -guided missile ) at the aircraft, the RWR may be able to detect the change in mode that the radar must use to guide the missile and notify the pilot with much more insistent warning tones and flashing, bracketed symbols on

6222-535: The correct target is hit in a specific area of the ship. An LRASM can find its own target autonomously by using its passive radar homing to locate ships in an area, then using passive measures once on terminal approach. Like the JASSM, the LRASM is capable of hitting land targets. LRASM is designed to be compatible with the Mark 41 Vertical Launching System used on many U.S. Navy warships and to be fired from aircraft, including

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6324-416: The current aircraft heading (i.e. a radar straight ahead displayed at the top of the circle, directly behind at the bottom, etc.). The distance from the center of the circle, depending on the type of unit, can represent the estimated distance from the generating radar, or to categorize the severity of threats to the aircraft, with tracking radars placed closer to the center than search radars. The symbol itself

6426-577: The direction they came from (since in most cases a radar emitter and receiver are in the same location). They are less able to minimize radar reflections in other directions. Thus, detection can be better achieved if emitters are in different locations from receivers. One emitter separate from one receiver is termed bistatic radar ; one or more emitters separate from more than one receiver is termed multistatic radar . Proposals exist to use reflections from emitters such as civilian radio transmitters , including cellular telephone radio towers . By Moore's law

6528-507: The effort to make transparent aircraft ceased. In 1916, the British modified a small SS class airship for the purpose of night-time reconnaissance over German lines on the Western Front . Fitted with a silenced engine and a black gas bag, the craft was both invisible and inaudible from the ground but several night-time flights over German-held territory produced little useful intelligence and

6630-428: The enemy battlespace. Multiple missiles can work together to share data to coordinate an attack in a swarm. Aside from short, low-power data-link transmissions, the LRASM does not emit signals, which combined with the low- RCS JASSM airframe and low IR signature reduces detectability. Unlike previous radar-only seeker-equipped missiles that went on to hit other vessels if diverted or decoyed, the multi-mode seeker ensures

6732-568: The exhaust plume. Another way to reduce the exhaust temperature is to circulate coolant fluids such as fuel inside the exhaust pipe, where the fuel tanks serve as heat sinks cooled by the flow of air along the wings. Ground combat includes the use of both active and passive infrared sensors. Thus, the United States Marine Corps (USMC) ground combat uniform requirements document specifies infrared reflective quality standards. In addition to reducing infrared and acoustic emissions,

6834-426: The ferrite layer. FSS are used for filtration and microwave absorption. Shaping offers far fewer stealth advantages against low-frequency radar . If the radar wavelength is roughly twice the size of the target, a half-wave resonance 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

6936-403: The field on the so-called dirty birds but results were disappointing, the weight and drag increases were not worth any reduction in detection rates. More successful was applying camouflage paint to the originally bare metal aircraft; a deep blue was found to be most effective. The weight of this cost 250 ft in maximum altitude, but made the aircraft harder for interceptors to see. In 1958,

7038-619: The functions of aircraft flight control systems such as ailerons , elevators , elevons , flaps , and flaperons 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 (for faster, stronger control response to change vehicle orientation to reduce detection). Two promising approaches are flexible wings, and fluidics. Radar warning receiver Depending on

7140-530: The fuselage, and radar-absorbent paint. The United States Army issued a specification in 1968 which called for an observation aircraft that would be acoustically undetectable from the ground when flying at an altitude of 1,500 ft (460 m) at night. This resulted in the Lockheed YO-3A Quiet Star , which operated in South Vietnam from late June 1970 to September 1971. During the 1970s,

7242-532: The gaps filled with ferrite-based RAM. The pyramidal structure deflects the incident radar energy in the maze of RAM. One commonly used material is called iron ball paint . It contains microscopic iron spheres that resonate in tune with incoming radio waves and dissipate most of their energy as heat, leaving little to reflect back to detectors. FSS are planar periodic structures that behave like filters to electromagnetic energy. The considered frequency-selective surfaces are composed of conducting patch elements pasted on

7344-586: The idea was dropped. Diffused lighting camouflage , a shipborne form of counter-illumination camouflage, was trialled by the Royal Canadian Navy from 1941 to 1943. The concept was followed up for aircraft by the Americans and the British: in 1945, a Grumman Avenger with Yehudi lights reached 3,000 yards (2,700 m) from a ship before being sighted. This ability was rendered obsolete by radar . Chaff

7446-418: The invention of electromagnetic metasurfaces , the conventional means to reduce RCS have been improved significantly. As mentioned earlier, the main objective in purpose shaping is to redirect scattered waves away from the backscattered direction, which is usually the source. However, this usually compromises aerodynamic performance. One feasible solution, which has extensively been explored in recent time,

7548-476: The jet exhaust is vented above the wing surface to shield it from observers below, as in the Lockheed F-117 Nighthawk, and the unstealthy Fairchild Republic A-10 Thunderbolt II . To achieve infrared stealth , the exhaust gas is cooled to the temperatures where the brightest wavelengths it radiates are absorbed by atmospheric carbon dioxide and water vapor , greatly reducing the infrared visibility of

7650-701: The late eighties when the Lockheed Martin F-117 stealth fighter became widely known. The first large scale (and public) use of the F-117 was during the Gulf War 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 in 1989. Stealth aircraft are often designed to have radar cross sections that are orders of magnitude smaller than conventional aircraft. The radar range equation meant that all else being equal, detection range

7752-405: The market the RWR system is designed for, it can be as simple as detecting the presence of energy in a specific radar band, such as the frequencies of known surface-to-air missile systems. Modern RWR systems are often capable of classifying the source of the radar by the signal's strength, phase and signal details. The information about the signal's strength and waveform can then be used to estimate

7854-415: The material's surface. Composites may also contain ferrites to optimize the dielectric and magnetic properties of a material for its application. Radiation-absorbent material (RAM), often as paints, are used especially on the edges of metal surfaces. While the material and thickness of RAM coatings can vary, the way they work is the same: absorb radiated energy from a ground- or air-based radar station into

7956-520: The missile. On 7 February 2020, the U.S. Department of State announced it had approved a possible foreign military sale to Australia of up to 200 LRASMs and related equipment for an estimated cost of US$ 990 million. In July 2020, Australia announced that it was acquiring the LRASM for their F/A-18F Super Hornet fighters. [REDACTED]   United States [REDACTED]   Australia Stealth technology Stealth technology , also termed low observable technology ( LO technology ),

8058-408: The missile. For example, the rate of closure and aspect of the incoming missile may allow the pilot to determine that if they dive away from the missile, it is unlikely to catch up, or if it is closing fast, that it is time to jettison external supplies and turn toward the missile in an attempt to out-turn it. The RWR may be able to send a signal to another defensive system on board the aircraft, such as

8160-488: The noise or acoustic signature of the rotor over a greater range of frequencies. The simplest technology is visual camouflage ; the use of paint or other materials to color and break up the lines of a 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 , and it

8262-501: The outset to have a chosen spectral signature . The degree of stealth embodied in a given design is chosen according to the projected threats of detection. Camouflage to aid or avoid predation predates humanity, and hunters have been using vegetation to conceal themselves, perhaps as long as people have been hunting. The earliest application of camouflage in warfare is impossible to ascertain. Methods for visual concealment in war were documented by Sun Tzu in his book The Art of War in

8364-399: The pilot when he should change altitude and mission planning also considers altitudes where the probability of their formation is minimized. In space, mirrored surfaces can be employed to reflect views of empty space toward known or suspected observers; this approach is compatible with several radar stealth schemes. Careful control of the orientation of the satellite relative to the observers

8466-400: The potency of detection and interception technologies ( radar , infrared search and tracking , surface-to-air missiles , etc.) have increased, 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 signature . A modern stealth vehicle is designed from

8568-418: The processing power behind radar systems is rising over time. This will eventually erode the ability of physical stealth to hide vehicles. Synthetic aperture sidescan radars can be used to detect the location and heading of ships from their wake patterns. These are detectable from orbit. When a ship moves through a seaway it throws up a cloud of spray which can be detected by radar. Acoustic stealth plays

8670-597: The protest, holding an award to any other source would be likely to cause substantial duplication of costs that were not expected to be recovered through competition, and unacceptable delays in meeting the Government's needs. The Navy was authorized by the Pentagon to put the LRASM into limited production as an operational weapon in February 2014 as an urgent capability stop-gap solution to address range and survivability problems with

8772-405: The same angles. The effect of this is to return a narrow radar signal in a very specific direction away from the radar emitter rather than returning a diffuse signal detectable at many angles. The effect is sometimes called "glitter" after the very brief signal seen when the reflected beam passes across a detector. It can be difficult for the radar operator to distinguish between a glitter event and

8874-410: The signals are first deinterleaved to sort the mixture of incoming signals by emitter type. These data are then further sorted by threat priority and displayed. The RWR is used for identifying, avoiding, evading or engaging threats. For example, a fighter aircraft on a combat air patrol (CAP) might notice enemy fighters on the RWR and subsequently use its own radar set to find and eventually engage

8976-428: The size of its 1,000 lb (450 kg) warhead to increase range from some 300 mi (480 km) to 1,000 mi (1,600 km), the missile would still be powerful enough to destroy or disable warships while having the reach to hit inland targets. With the proper guidance system, a single missile would increase the Navy's flexibility rather than needing two missiles specialized for different roles. The program

9078-487: The surfaces of aircraft. Such changes to shape and surface composition comprise stealth technology as currently used on the Northrop Grumman B-2 Spirit "Stealth Bomber". The concept of stealth is to operate or hide while giving enemy forces no indication as to the presence of friendly forces. This concept was first explored through camouflage to make an object's appearance blend into the visual background. As

9180-442: The tail, stealth design must bury the engines within the wing or fuselage , or in some cases where stealth is applied to an extant aircraft, install baffles in the air intakes, so that the compressor 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

9282-404: The target area. Two launches from vertical launch systems were planned for summer 2014. The missile had a sensor designed by BAE Systems . The sensor is designed to enable targeted attacks within a group of enemy ships protected by sophisticated air defense systems. It autonomously located and targeted the moving surface ship. The sensor uses advanced electronic technologies to detect targets within

9384-438: The target without the presence of prior, precision intelligence, or supporting services like Global Positioning Satellite navigation and data-links. These capabilities will enable positive target identification, precision engagement of moving ships and establishment of initial target cueing in extremely hostile environments. The missile will be designed with counter-countermeasures to evade hostile active defense systems. The LRASM

9486-549: The threat. In addition, the RWR helps identify and classify threats—it's hard to tell which blips on a radar console-screen are dangerous, but since different fighter aircraft typically have different types of radar sets, once they turn them on and point them near the aircraft in question it may be able to tell, by the direction and strength of the signal, which of the blips is which type of fighter. A non-combat aircraft , or one attempting to avoid engagements, might turn its own radar off and attempt to steer around threats detected on

9588-452: The type of threat the detected radar poses. The RWR usually has a visual display somewhere prominent in the cockpit (in some modern aircraft, in multiple locations in the cockpit) and also generates audible tones which feed into the pilot's (and perhaps RIO /co-pilot/ GIB 's in a multi-seat aircraft) headset. The visual display often takes the form of a circle, with symbols displaying the detected radars according to their direction relative to

9690-568: The visibility of military aircraft. Single examples of the Fokker E.III Eindecker fighter monoplane, the Albatros C.I two-seat observation biplane, and the Linke-Hofmann R.I prototype heavy bomber were covered with Cellon . However, sunlight glinting from the material made the aircraft even more visible. Cellon was also found to degrade quickly from both sunlight and in-flight temperature changes, so

9792-597: Was applied by Lockheed in computer simulation to design a novel shape they called the "Hopeless Diamond", a wordplay on the Hope Diamond , securing contractual rights to produce the F-117 Nighthawk starting in 1975. 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 Northrop Grumman Tacit Blue also played

9894-434: Was awarded the first production award for the air-launched LRASM; low-rate initial production Lot 1 includes 23 missiles. On 27 July 2017, Lockheed announced they had successfully conducted the first launch of an LRASM from an angled topside canister using a Mk 114 booster, demonstrating the missile's ability to be used on platforms lacking vertical launch cells. On 17 August 2017, the LRASM conducted its first flight test in

9996-636: Was estimated to have a maximum range of 500 nmi (930 km). However, LRASM's range is shorter than the JASSM-ER it is based upon, due to the extra space for the navigation/sensor/passive radar needs. Lockheed Martin has claimed the missile's range is greater than 200 nmi (370 km). To ensure survivability to and effectiveness against a target, the LRASM is equipped with a BAE Systems -designed seeker and guidance system, integrating jam-resistant GPS/INS, an imaging infrared (IIR infrared homing ) seeker with automatic scene/target matching recognition ,

10098-592: Was initiated in 2009 and started along two different tracks. LRASM-A is a subsonic cruise missile based on Lockheed Martin's 500 nm-range AGM-158 JASSM-ER ; Lockheed Martin was awarded initial development contracts. LRASM-B was planned to be a high-altitude supersonic missile along the lines of the Indo-Russian BrahMos , but it was cancelled in January 2012. Captive carry flight tests of LRASM sensors began in May 2012;

10200-558: Was invented in Britain and Germany early in World War II as a means to hide aircraft from radar. In effect, chaff acted upon radio waves much as a smoke screen acted upon visible light. The U-boat U-480 may have been the first stealth submarine. It featured an anechoic tile rubber coating, one layer of which contained circular air pockets to defeat ASDIC sonar. Radar-absorbent paints and materials of rubber and semiconductor composites (codenames: Sumpf , Schornsteinfeger ) were used by

10302-899: Was the first coastal defence and the French La Fayette-class frigate the first ocean-going stealth ship to enter service. Other examples are the Dutch De Zeven Provinciën class frigates, the Taiwanese Tuo Chiang stealth corvette , German Sachsen-class frigates , the Swedish Visby-class corvette , the USS San Antonio amphibious transport dock , and most modern warship designs. Dielectric composite materials are more transparent to radar, whereas electrically conductive materials such as metals and carbon fibers reflect electromagnetic energy incident on

10404-509: Was translated into English with the same title by the U.S. Air Force, Foreign Technology Division. The theory played a critical role in the design of American stealth-aircraft F-117 and B-2. Equations outlined in the paper quantified how a plane's shape would affect its detectability by radar, termed radar cross-section (RCS). At the time, the Soviet Union did not have supercomputer capacity to solve these equations for actual designs. This

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