October 19, 2019
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Fire and forget
Laser guided bombs and munitions

Nowadays, laser and GPS guided weapons have become a requisite for advanced air forces, which means that fighters need an integrated weapon in order to remain competitive. LGBs are maneuverable, free-fall weapons requiring no electronic interconnect to the aircraft. They have an internal semi-active guidance system that detects laser energy and guides the weapon to a target illuminated by an external laser source. The designator can be located in the delivery aircraft, another aircraft, or a ground source.

The development of laser guided weapons has dramatically improved the accuracy of weapon guidance and delivery. With the assistance of build-up guidance kits, general GP bombs are turned into laser-guided bombs (LGBs). The kits consist of a computer- control group (CCG), guidance canards attached to the front of the warhead to provide steering commands, and a wing assembly attached to the aft end to provide lift.

Laser-guided weapons were first developed in the United States in the early 1960s and used operationally in Vietnam, starting in 1968. Although there were a variety of technical and operational problems, the results were generally positive. LGBs proved to offer a much higher degree of accuracy than unguided weapons. Confronted with tough targets and strong air defenses in the bombing campaign against North Vietnam, the US Navy and Air Force developed glide bombs guided by television and laser beams, and such weapons have been refined ever since.

Guidance kit

Most laser-guided bombs are produced in the form of strapon kits: seeker heads, and steering fins that can be attached to a standard general-purpose bomb or penetration bomb. Such kits are modular, allowing relatively easy upgrades, and are considerably cheaper than purpose-built weapons.

A laser guidance kit is integrated with each bomb to add the requisite degree of precision. The kit consists of a computer control group at the front end of the weapon and an airfoil group at the back. When a target is illuminated by a laser - either airborne or ground-based - the guidance fins (canards) react to signals from the control group and steer the weapon to the target. Wings on the airfoil group add the lift and aerodynamic stability necessary for in-flight maneuvering.

All LGB weapons have a CCG, a warhead (bomb body with fuze), and an airfoil group. The computer section transmits directional command signals to the appropriate pair(s) of canards. The guidance canards are attached to each quadrant of the control unit to change the flight path of the weapon. The canard deflections are always full scale (referred to as “bang, bang” guidance).

The LGB flight path is divided into three phases: ballistic, transition, and terminal guidance. During the ballistic phase, the weapon continues on the unguided trajectory established by the flight path of the delivery aircraft at the moment of release. During the transition phase, the weapon attempts to align its velocity vector with the line-of-sight vector to the target. During terminal guidance, it attempts to keep its velocity vector aligned with the instantaneous line-of- sight.

Laser-guided munitions use a laser designator to mark a target. The reflected laser light from the target is then detected by the seeker head of the weapon, which sends signals to the weapon’s control surfaces to guide it toward the designated point.

With their capability to pierce hard surfaces, the LGBs can also be used to destroy the enemy’s concrete runways and fortified locations.

While LGBs are highly accurate under ideal conditions, they present several challenges for successful use. The first problem is target designation. To overcome these problems, GPS guidance is being seen as a viable backup to upgrade LGBs to function in all weather conditions. These weapons such as the US Air Force Enhanced Guided Bomb Unit (part of the Paveway family of LGBs), use laser designation for precision attacks, but contain an inertial navigation system (INS) with GPS receiver for back-up.

The Indian Air Force (IAF) used the laser-guided bombs for the first time during the 1999 Kargil War. The IAF learnt its lessons well from the Kargil experience and has made sincere efforts to enhance its precision attack capabilities by widening the use of LGBs on its different combat aircraft fleets. The IAF also continues to enhance its arsenal of LGBs through indigenous and direct import routes.

Almost all frontline fighter aircraft of IAF have the capability to launch LGBs. The IAF plans to induct more than 100 bunker-buster LGBs for its Jaguar warplanes to destroy strongly fortified enemy targets. For that Lockheed Martin has bagged a deal expected of around Rs 100 crore for supplying laser-guided bombs (LGBs) for the Jaguar fighter aircraft fleet in the Indian Air Force.

LGBs are guided projectiles that use lasers to strike a designated target with greater accuracy than a gravity bomb and were used with high accuracy by the IAF against Pakistani Army posts during the Kargil war in 1999. Around the same time, the US had supplied some Paveway bombs to India which could be launched from the Jaguar and Mirage 2000 planes for accurately striking enemy targets.

In its continuous efforts to do so, India has successfully developed its first type of laser guided bomb (LGB), lifting the precision attack capability of the IAF. The indigenous LGB, called Sudarshan, is developed by DRDO as part of self-dependency in the advanced weapon developments. The weight of the LGB is about 450 kg. The bomb contains a laser designator, which could illuminate the ground target and guide the bomb to launch its precise attack, said the official.

Currently, LGBs are one of the most common precision-guided munitions in the world, and widely deployed by the world’s air forces, such as the United States, Russia, France and Britain.

Paveway bombs

The Paveway family of laser guided bombs has revolutionized tactical air-to-ground warfare by converting “dumb” bombs into precision guided munitions. Paveway bombs have been put to the test in every major conflict and proved themselves, time and again, as the weapon of choice by the end-users. Paveways made up more than half the air-to-ground precision guided weapons used in Operation Iraqi Freedom.

Newer versions of Paveway include GPS/INS guidance capabilities. This innovation combines the accuracy and flexibility of traditional laser-guided weapons with the all-weather capability of GPS guidance, resulting in a weapon that decreases the required sortie count and weapon inventory while simultaneously increasing the mission success rate.

In the early 1970s, the initial Paveway was replaced by the Paveway II, which featured an enhanced but also simpler and cheaper seeker head and pop-out fins to improve the weapon’s glide characteristics and make it easier to fit to an aircraft. The new LGBs based on the Paveway II were given the designations GBU-12 (225 kilograms), GBU-16 (450 kilograms), and GBU-10 (900 kilograms). The Paveway II required the launch aircraft to operate from medium altitude, leaving the aircraft vulnerable to ground defenses.

As the Vietnam War progressed and experience with laser guided bombs increased, Air Force leaders discovered the need for a greater variety of LGBs to increase effectiveness against certain targets. A smaller bomb with greater maneuverability was also required to attack the many small and moving targets on the Ho Chi Minh trail. The Air Force adapted the 500 lb Mk-82 GP, later called the GBU-12.

The Guided Bomb Unit-12 (GBU-12) utilizes a Mk82 500-pound general purpose warhead. The operator illuminates a target with a laser designator and then the munition guides to a spot of laser energy reflected from the target.

The GBU-12 is a member of the Paveway II series of laser guided bombs (LGBs). These weapons are hybrids. At the core of each is a bomb: a 500-pound Mk 82 for the GBU-12, a 1,000-pound Mk 83 for the GBU-16 and a 2,000-pound Mk 84 for the GBU-10. The munition was used during Operation Desert Storm, and, according to the Air Force, hit 88 percent of its targets.

There are two generations of GBU-12 LGBs: Paveway I with fixed wings and Paveway II with folding wings. Paveway II models have the following improvements: detector optics and housing made of injection-molded plastic to reduce weight and cost; increased detector sensitivity; reduced thermal battery delay after release; increased maximum canard deflection; laser coding; folding wings for carriage, and increased detector field of view.

The Enhanced-GBU-12 [EGBU-12] is a dual-mode guided bomb designed to effectively operate in all-weather conditions. Enhanced Paveway II features a GPS-aided Inertial Navigation System as well as a laser guidance system to offer one precision guided weapon for all situations. The resulting dual-mode capability offers true all-weather operational flexibility not found in other weapons systems being produced: GPS guidance for poor weather conditions and precise laser guidance when required for mobile targets of opportunity.

French AASM

French - France’s Armement Air-Sol Modulaire (AASM) is similar in concept to the American GPS-guided JDAM bomb, but its execution includes several key differences. The global trend toward GPS-guided weapons makes a French entry important for industrial as well as operational reasons, and the Sagem/MBDA team hope AASM will earn them a market niche.

The AASM is a rocket propelled bomb with terminal guidance, capable of very high precision attacks on targets at a range of more than 60 km. In other words, it can be fired by Rafale or Mirage fighters from a comfortable standoff distance, outside the reach of enemy air defenses. The AASM stands out because it’s a modular weapon system, totally autonomous and jam-proof, flying resolutely towards its target once the coordinates have been manually loaded into the onboard computer by the pilot. The most advanced AASM models, like the Laser version now undergoing final tests, allow the modification of terminal guidance if needed to hit moving targets.

The AASM made a discreet debut in the spring of 2008, when the French air force deployed a 250-kg version in Afghanistan. Today, it is part of the standard combat suite carried by the Dassault Rafale F3 multirole fighter. In fact, it’s an integral part of the tactical air-to-ground arsenal deployed by both the French air force and naval air arm, and has also been chosen by the Royal Moroccan air force as part of their current program to modernize Mirage F1 fighters. The AASM Hammer is a medium-range guided weapon that can be used day or night and under all weather conditions – which is not the case of regular laser guided bombs, which have to be launched in the vicinity of air defense systems. Furthermore, these bombs’ guidance may be compromised, or even rendered ineffective by cloud cover or hard rain.

Furthermore, the AASM ”Hammer” is a family of precision weapons, with guidance and propulsion kits fitted to standard bombs of different sizes: 125 kg, 250 kg, 500 kg and 1,000 kg – the latter dubbed the “bunker buster” because of its ability to penetrate several meters of reinforced concrete. The aft-mounted propulsion kit comprises a solid rocket motor and four winglets for flight control, deployed when the weapon is released.

The most commonly used version today is the SBU-38 (Smart Bomb Unit) AASM 250, with hybrid inertial/GPS guidance. There is also the SBU-54 version, combining an inertial guidance system (INS), GPS correction and terminal guidance via an infrared imager (IIR). The latest addition to the family is the SBU-64, which adds laser terminal guidance to the INS/GPS hybrid package, enabling the AASM to hit moving or even highly agile targets.

The AASM’s sophisticated terminal guidance means that this weapon features capabilities unmatched by a conventional laser guided bomb. In particular, the AASMoffers a virtually vertical terminal trajectory, enabling it to attack, for example, a tank hidden behind a sand embankment or a concrete wall, or even a target in a narrow street or trench.

To date, the French air force has deployed about one hundred bombs in combat, all the SBU-38 INS/GPS version. This uses the basic guidance kit, with three inertial gyros whose directional pulses are managed by a Kalman filter and corrected in real time by satellite data from a military-standard GPS.

Deploying both Mica air-to-air missiles and Hammer air-to-ground weapons, the Rafale fighters deployed in Libya have demonstrated unprecedented operational flexibility.

Israeli MLGB

The Medium-weight Laser Guided Bomb (MLGB) is a small dual-mode guided weapon developed by Israel Aerospace Industries (IAI) and intended for carriage by light attack aircraft and UAVs. Israel Aerospace Industries (IAI) unveiled the MLGB (Medium Range Laser Guided Bomb) at Le Bourget in 2011.

The evolving MLGB program demonstrates that Israeli designers have joined the wider trend to develop and field lightweight precision guided munitions (PGMs), with an emphasis on those than can be carried by UAVs. IAI describes the MLGB as “a cost effective weapon for precision attacks and close air support against various types of targets such as buildings, small bunkers, time critical targets and moving targets.”The MLGB is a dual-mode weapon that incorporates both semi-active laser homing and a GPS satellite guidance function. These two modes can be combined for greater accuracy, or used independently when target conditions or a lack of targeting data precludes the use of one particular mode.

The MLGB is capable of dual mode guidance: homing in on a target via a laser beam or feeding coordinates into its GPS mechanism. The bomb is designed to attack both stationary and mobile objects. Mission parameters are transmitted to the weapon prior to its release from the aircraft. Once in flight, it corrects its path until final approach to target.

The MLGB can be dropped from fighter planes or light attack aircraft. Weighing 115 kilos and 170 cm long, it’s especially suited for tasks demanding minimal collateral damage thanks to its high degree of accuracy and relatively small warhead. In addition, MLGB has a multi-purpose fuze that can be used above the target, on the target, or to penetrate the target. MLGB is highly effective against variety of target types, including static or moving ground targets and ships.

Combined with an on-board targeting and laser designation system, or coordinated with laser designators on other platform or on the ground, MLGB provides rapid look-shoot target attack.

The bomb provided as a unified weapon (unlike other laser guidance kits) comes with GPS/INS and laser guidance, and a three-mode fuse, offering airburst, impact or delayed detonation of the warhead effectively defeating soft, surface or semi-protected targets such as buildings or vehicles.

Terminal homing on a laser designation spot enables pinpoint accuracy when required. Prior to release, the MLGB is powered up and mission parameters are loaded.  Upon release, a midcourse navigation trajectory is executed with transition to terminal homing taking place in the final flight stage, using a combination of GPS and semi- active laser (SAL) guidance. With high precision and relatively lightweight warhead MLGB provides an option for an offensive effect while minimizing collateral damage and risk of fratricide.

The MBT division of IAI produces conversion kits for “smart bombs”: the 5m-CEP Griffin LGB (Laser Guided Bomb) and the NGLGB (Next Generation Laser Guided Bomb).

These weapons provide Air Forces with high precision, 12km standoff strike capability against ground targets such as bunkers, entrenched tanks, armored vehicles and other hardened targets. This capability enables to attack highly defended targets while eliminating aircraft and aircrew losses, and ensures cost effective operations, killing more targets with less ammunition.

The conversion kits are compatible with the Mk-82/83/84 GP and other bombs. The kit comprises a front guidance section and a rear fins section, which are attached to a standard bomb, converting it to a “smart” bomb”. MBT’s smart bombs are combat proven. They can be carried by many types of fighter aircraft, and used with all available designators.

Chinese LGB

The LeiTing-2 (LT-2, LeiTing = “Thunder”), also known as GB1 in its export name, is the first Chinese domestically built laser guided bomb (LGB) that has entered operational service with the PLA. First revealed to the public in October 2006, the LT-2 bears a great deal of similarity to the Russian KAB-500L in appearance, forcing one to think that it may be a licensed or reverse-engineered copy of the Russian design. The 500kg bomb can be carried by a range of aircraft including JH-7, Q-5, FC-1, J-8B, and J-10.

China has been developing the LGB technology since the late 1980s, but with no known success before the introduction of the LT-2. Initially the Chinese LGB development used the US design as a prototype.

In the early 1990s China North Industries Group Corporation (NORINCO) revealed a LGB similar to the US Paveway-II in appearance. China has also developed a range of laser targeting pods to be carried by combat aircraft for weapon guidance. An early design known as “Blue Sky” introduced in the late 1990s appeared to be similar to the US LANTIRN navigation and targeting pod. But development of the LGB accelerated after 2000 with Russian assistance.

The LT-2 uses a semi-active laser guidance system, which requires a laser designator to “illuminate” the target for the weapon. The LT-2 could be guided by a laser targeting pod either carried by the same aircraft or onboard another aircraft. Alternatively it could also be guided by a land-based laser designator operated by the ground crew. The operational range is 15km for the airborne laser targeting pod and 7km for the land-based laser designator. The accuracy is estimated to be around 6.5m CEP.

Russian bomb

Russia’s family of KAB-1500, KAB-500 and KAB-250 smart bombs is an equivalent to the US Paveway II/III, GBU-8/15, and GBU-31/32 JDAM families of guided bombs. Sharing common design modules with unique seeker designs, and a range of standard warhead types, this family of weapons encompasses all of the baseline capabilities in their US equivalents.

The KAB (Korrektiruyeskaya Aviatsionnaya Bomba) family of weapons were developed during the 1970s by Moscow based GNPP Region, now part of Tactical Missiles Corporation. A number of different seeker/guidance packages are available for these weapons, which can be supplied with a wide range of compatible warheads. In this fashion the optimal configuration for specific roles and missions can be chosen.

The Su-27/30 Flanker and Su-34 Fullback are cleared to lift up to 6 KAB-500s or 3 KAB-1500s on wing stations 3 and 4, inlet stations 9 and 10, and centreline tandem stations 1 and 2. The KAB-500 is carried on a BD-3U adaptor, the KAB-1500 on a BD4 adaptor. The APK-9E Tekon datalink pod, used for some variants, is carried on inlet station 9, as is the Thales Damocles pod.

Russian industry manufactures a number of laser designators such as the Klyon PM/PS, Kaira 24M, I-25 Shkval, or a targeting pod such as the Sapsan-E. Recently the French Thales Damocles pod was licensed, with the laser exciter configured with Russian seeker coding.

ATK guided munition

ATK is developing a lightweight precision guided munition, compact and light enough to be carried by the dozens or even hundreds by unmanned aerial aircraft. The miniature guided weapon from ATK weighs about six pounds. Fitted with three folding air surfaces and moving tail fins for flight control, the weapon uses laser and GPS to home in on targets designated by the UAV or by supported ground forces.

The weapon weighs about six pounds (2.7 kg). Its hand-grenade size warhead makes more than half that weight. The resulting effect offers maximum lethality against exposed targets, with minimal collateral damage to their surrounding.

The new glide weapon is packed into a conformal container launcher carried under the wing of the Shadow, fitted on top of the strut root. Upon release the weapon’s fins are extracted and three airfoils pop into place, as the weapon glides on its path to the ground. As the three laser detectors are activated, they seek laser signals reflected from the designated target. Once the laser spot is detected, the weapon’s flight control processor computes the necessary corrections and activates the tail fins to point the weapon on the course homing in on the spot, hitting the target with high precision.

The miniature guided weapon currently under development could, potentially, replace current cluster weapons banned by international treaties. When employed in weapon systems, individually targeted guided weapons could be directed to scatter over the area to focus on specific target location, guided by GPS or disperse over a specific area in a pattern maximizing the desired effect. Optional carriers such as new cruise missiles, or loitering weapons, will be able to employ such guided sub-munitions to attack multiple targets along their flight path, on a single mission.

Lockheed weapon

The Lockheed Martin Paveway II Dual Mode Laser Guided Bomb (DMLGB) is the next generation laser guided bomb kit that uses the existing Paveway II Laser Guided Bomb infrastructure and upgrades the existing Computer Control Group (CCG) system with an Inertial Navigation System/Global Positioning System (INS/GPS), an all-weather guidance system that provide dual-mode guidance capability.

With the combination of the upgraded INS/GPS system, existing SAL (semi-active laser) seeker and anti-jam technology, the DMLGB minimizes collateral damage and improves mission effectiveness by providing precision strike capabilities in all weather at extended standoff ranges. The DMLGB is effective against fixed, relocatable and moving targets.

Recently, keeping in mind the increasing combat role of tactical UAVs, Lockheed Martin successfully launched the ‘Shadow Hawk’ precision-guided weapon from a Shadow 200 Unmanned Aircraft System (UAS), achieving a direct hit on the target.

The new guided munition is a five kg (11-pound) class, seven centimeter diameter (2.75-inch), 68 cm long (27-inch) drop-glide guided weapon that uses semi-active laser (SAL) seeker for terminal guidance. Shadow Hawk provides better than one meter precision and has effective off-axis capability, enabling engagement of designated targets off the aircraft’s wing. The weapon is equipped with an anti-personnel warhead optimized for the mission at hand and the TUAV platform class. Its low weight enables the Shadow UAS to maintain longer time-on-station for performing critical reconnaissance, surveillance and target acquisition operations.

Shadow Hawk’s sensor package, guidance electronics and control section successfully navigated the weapon to the target, hitting it just eight inches off the laser spot center. For this initial demonstration, the target was designated with a ground location laser designator.

Few years ago Lockheed Martin conducted another small weapon in a similar test profile. The Scorpion was about twice the size of the current Shadow Hawk. Back then the ‘Scorpion’ was launched from a C-130 aircraft, probably as part of the evaluation of weapon alternatives for the Marine Corps’ KC-130J Harvest Hawk program.

This weapon was designed to glide and hit targets at a maximum range of over 10 nautical miles. At that time the company said the Scorpion is adaptable to multiple launch platforms, including manned and unmanned systems. Scorpion was also said as being able to mount various seekers, including SAL, imaging infrared, shortwave infrared or millimeter wave seekers. The typical targets attributed to the Scorpion were described as structures, personnel, lightly armored vehicles, trucks, cars, missile launchers, and artillery or gun positions. Both weapons are based on elements developed for the 2.753 /70mm DAGR laser guided rocket, also developed by Lockheed Martin Missiles & Fire Control Systems.

Other companies that have demonstrated similar compact, lightweight precision attack munitions for UAVs include Raytheon, ATK and DRS Technologies. Among these systems the Small Tactical Munition II from Raytheon weighs about 13.5 pounds. Raytheon proposes stacking two such miniature guided weapons carried in tandem in a CLT. The Shadow could take a total of four such weapons, or only two, in an asymmetric configuration, providing more fuel for extended endurance. Another weapon developed by ATK is the Hatchet. It is even smaller, each weighing about four pounds. ATK designed a specialized pylon for the Shadow, also carrying two Hatchets.

MBDA SABER

MBDA Missile Systems have unveiled a small laser plus GPS/INS guided weapon. The weapon called Small Air Bomb Extended Range (SABER) can be configured as a rocket or glide weapon, according to the customer’s requirements. The dual mode warhead uses blast-fragmentation or shaped charge, for reduced collateral damage and penetration effect. The SABER uses a semi-active laser seeker for terminal guidance, and GPS/INS mid-course navigation enabling the weapon to fly off-axis, regardless to the direction of the launching platform.

The unpowered version of SABER weighs only 10 pounds, and its range is dependent on the launch altitude, with the rocket powered version adapted for low altitude launch, weighing about 30 pounds.

The 13-pound Saber is essentially a much smaller version of the Small Diameter Bomb used onboard Air Force fighters. It uses both laser-based and GPS guidance systems to track potential targets. The current weapon of choice for larger unmanned aircraft, like the Air Force Predator or Army Gray Eagle, is the Hellfire rocket. But the smaller Shadow can’t support the Hellfire’s massive size and weight. The Saber, on the other hand, can be fielded by the Shadow.  

An alternative seeker employing TV/IR sensor with data-link communications enabling ‘man in the loop’ control is currently in development.

SABER provides exceptional lethality and precision for UAS weapon systems by using GPS/INS guidance and SAL seeker. The SABER family provides 120 or 30lb rocket or glide capability depending on customer requirements.

Rafael’s Spice

The SPICE (Smart, Precise-Impact and Cost-Effective Guidance Kits) converts a standard MK-83 or MK-84 bomb into a stand-off autonomous weapon system with high accuracy in all operational scenarios.

Spice uses state-of-the-art navigation, guidance and homing techniques to achieve accurate and effective destruction of high-value enemy targets. Spice’s Automatic Target Acquisition capability employs unique scene-matching technology that is robust to scenery changes, counter-measures, navigation errors and target location errors. The technology compares a real-time image received from the dual CCD/IIR seeker to a reference image stored in the weapon’s computer.

In the homing phase, after successful completion of the scene-matching process, Spice acquires the target automatically. The weapon homes in accurately and autonomously to the exact target location in the pre-defined impact angle and azimuth.

Spice-2000 consists of an add-on kit for warheads such as the MK-84, BLU-109, RAP-2000 and others. Spice-1000 consists of an add-on kit for warheads such as the MK-83, BLU-110, RAP-1000 and others. The weapon has unique deployable wings that substantially increase its range and facilitate the integration to light fighter aircraft.

Spice has day, night and adverse weather capabilities, based on its dual CCD/IIR seeker. The Automatic Target Acquisition capability is implemented by a unique scene-matching technology that is robust to scenery changes, countermeasures, navigation errors and Target Location Errors. Spice navigates autonomously by means of INS/GPS and its seeker provides positive target identification.

Spice is combat-proven in the Israeli Air Force and is in service with leading air forces throughout the world. The system is also being considered by other international customers.

Spice is easily carried and operated from single and dual-seater fighter aircraft such as the F-15, F-16, F-18, Tornado, Mirage, Rafale Gripen and Eurofighter. Use of a common aircraft interface and sophisticated weapon software simplify the effort needed for aircraft integration.

With the missions of Tactical Unmanned Aerial Systems (TUAS) evolving from pure reconnaissance into armed recce, targeting and selectively engaging targets at very short response cycles, Air Forces and Armies around the world are looking for low cost, high precision and compact aerial weapons that could be delivered from TUAS in the most effective way without compromising mission performance. This requirement demanded the introduction of a new class of lightweight guided weapons. Several companies have already demonstrated such weapons. LGBs and PGMs can greatly improve the aerial striking accuracy on the ground targets. The IAF still has a long way to go before it acquires desired level of ‘PGM’ capability.