v1.6.0 / chapter 11 of 13 / 01 nov 06 / greg goebel / public domain
* The development of smart bombs and missiles has taken a jump forward in the last decade. This chapter outlines leading-edge developments in smart air-to-surface munitions. It also covers "smart" artillery munitions as a footnote; such weapons are not air-launched, but the technology is so similar that it makes sense to discuss it here.
* The WCMD can be used to improve the accuracy of cluster bomb canisters carrying a wide variety of submunitions. One new submunition that can be used in this fashion is the "CBU-97/B Sensor Fuzed Weapon (SFW)" cluster bomb. The SFW carries a smart antiarmor submunition, designated the "BLU-108/B", that allows a single CBU to engage and destroy multiple armored targets simultaneously.
The SFW is an outgrowth of work on smart weapons by Textron Defense Systems beginning in the mid-1980s under the "Assault Breaker" effort. Development of such systems was accelerated by the defense cutbacks in the 1990s that have required the military to obtain "force multipliers" to make the best use of limited resources. Tests of the SFW began in the early 1990s and demonstrated the lethality of the weapon. In a test conducted in late 1991, for example, an F-16 dropped four SFW canisters from low altitude, which then dispersed a total of 40 BLU-108/B submunitions over a column of 24 vehicles. 17 hits were scored on 11 of the vehicles.
The CBU-97/B SFW is based on the standard TMD canister, and has a loaded weight of 450 kilograms (1,000 pounds). The SFW can attack armored vehicles over a wide footprint. The munition can be delivered at altitudes from 60 meters to 6 kilometers (200 to 20,000 feet). An F-16 can carry 4 SFWs, with each canister carrying ten BLU-108/B submunitions in two rows of 5, and each submunition containing four smart hockey-puck shaped "Skeet" warheads each. An F-15E can carry 10 SFWs.
Once a dispenser is released, a pyrotechnic charge pops open the TMD's three panels to release the ten submunitions. Each submunition is a cylinder that is decelerated by a small parachute. The parachute also orients the submunition vertically over the target area. Chute deployment timing is staggered to allow the submunitions to disperse, and the actual area covered is a function of aircraft speed and the timing interval selected.
As the cylinder descends, the four Skeet warheads flip out from the body of the submunition. Each Skeet consists of a 13.3 centimeter (5.25 inch) diameter disk of flat copper backed by an explosive charge that is boresighted to a protruding infrared sensor. Once the cylinder is aligned properly over the target area, the parachute is cut loose as a rocket motor fires through two nozzles, which are canted so that they stop the cylinder's fall and start it spinning. Once the cylinder is spinning rapidly, the Skeets are released in pairs to spin away from the cylinder. They wobble in flight to allow the infrared sensor to scan over the ground below in a spiral pattern.
When a Skeet flies over a vehicle, the warhead's infrared sensor identifies it as a target and fires the explosive charge. This slams the wadded-up copper plate into the target at about 1,500 KPH (930 MPH), punching through armor and sending splinters through the interior. Explosive reactive armor is ineffective against such a "kinetic kill" projectile. If the Skeets don't find a target after a certain length of flight, they explode into fragments as a harassment measure and to prevent "pollution" of the landscape by hazardous dud submunitions.
The infrared sensor is capable of working through fog, since it is close to the target, and works at night and through electronic countermeasures. Not all the warheads are expected to find targets, but the dispersal pattern of the 40 Skeets carried by an SFW is expected to be effective against concentrated targets such as an armor column.
Although SFW development proved more troublesome than expected, baseline SFWs are now in the US military's inventory, and tests have demonstrated they are more lethal than required by their specifications. The US Air Force plans to obtain 5,000. They were introduced to combat during air strikes during the Kosovo campaign in 1999, with SFW-loaded CBUs acquiring the nickname of "cans of whup-ass".
Further development of the basic CBU-97 SFW has focused on adding the WCMD inertial guidance tailkit, resulting in the CBU-105/B SFW. The latest SFW configuration includes seeker improvements to permit attacks on naval vessels and even parked, cool aircraft and ground vehicles. The explosively-formed projectile scheme is being modified and enhanced, and a highly reliable self-destruct system is being considered to reduce collateral damage. The new projectile includes a ring of 16 explosively formed penetrators around the central main penetrator, providing an additional shotgun effect. In addition, a more insensitive explosive is used to meet Navy requirements for shipboard storage and handling.
* The Russians have fielded an SFW-class submunition, designated "SPBE-D" when used with a cluster-bomb unit and "MOTIV-3M" when used with the Smerch multiple-launch rocket system.
A Smerch rocket can carry five MOTIV-3M submunitions. Each MOTIV-3M submunition measures 284 x 255 x 186 millimeters (11.2 x 10 x 7.3 inches) and weighs 15 kilograms (33.1 pounds). When the missile arrives in the target area, the five submunitions are dispensed, with each popping out a parachute and then hunting for a target with a dual-band infrared seeker with a field of view of 30 degrees. At about 150 meters (500 feet) above the target, the submunition fires on its target, using an explosively-formed penetrator that can punch through 7 centimeters (2.75 inches) of armor.
* There has been work on new, much smarter submunitions. The US Air Force worked with Lockheed Martin to conduct a lengthy investigation of a submunition designated the "Low Cost Autonomous Attack System (LOCAAS)", which was effectively a small cruise missile, loaded up four to a TMD dispenser, that would conduct a search pattern around a target area, recognizing targets with a laser radar system and then attacking them with an explosively-formed projectile warhead.
While LOCAAS got as far as tests, there was no commitment to production and the program seems to have gone quiet. The Air Force does seem to be pursuing a number of loitering submunitions along the lines of LOCAAS with a confusing variety of designations -- the Boeing "Air Dominator" and the Lockheed-Martin "Surveilling Miniature Attack Cruise Missile (SMACM)" -- but it wise to take them with a grain of salt. The concept of "vaporware", invented by the computer industry, also applies to the arms industry.
This should not be interpreted as a slam. Investigation programs are just that, investigations, and there's no particular reason to believe that most weapon concepts being investigated will advance to operational status. The investigation may prove that the weapon isn't practical -- ineffective, too expensive, too unreliable, beyond the limits of current technology -- or even if it is, military requirements or funding may change, pushing the weapon off the bottom of the priority queue. Even weapons that do reach operational status may follow a confusing evolution through various programs, sometimes with changes in definition, before they reach the front lines.
As a good case in point, the US Army and Northrop Grumman developed another smart submunition, the "Brilliant Antiarmor Munition (BAT)". This 20 kilogram (44 pound) weapon looked like a cylinder about 1.5 meters (5 feet) long with a bulbous head when stored in its dispensing system. When released, the BAT popped out four wraparound tailfins and four long, straight cruciform gliding wings around the midbody. The bulbous nose was fitted with an infrared sensor, and the wingtips were fitted with long spikes fitted with acoustic sensors.
Once deployed, the BAT glided to a preprogrammed target location, with a cluster of BATs dispersing to ensure that they didn't attack the same targets, and used the acoustic sensors to identify the general location of a tank. Once a target was boxed by the acoustic sensors, the infrared sensor took over, directing the BAT to hit the target directly from the top, destroying it with a two-stage penetrating warhead. An Improved BAT (IBAT), with a combined millimeter-wave radar / infrared imager seeker, was also developed.
The plan was to deploy the BAT on the Block II version of the Army Tactical Missile System (ATACMS or "Attack 'Ems"), updated to carry a warload of 13 BATs. However, the Block II ATACMS was cancelled in 2003, and now it is unclear that BAT will ever be fielded. It seems plausible that a smart weapon that could smash enemy armor concentrations was no longer a particularly relevant weapon for the "dirty little wars" the Army was suffering through by that time. It might have been a nice thing to have, but other weapons were needed at the time.
The irony was that a simplified BAT ended up being a perfectly useful weapon. In the spring of 2003, the Army performed a demonstration of a laser-guided version of BAT named "Viper Strike". The weapons were carried on an Army Hunter drone at the end of March 2003 and scored seven hits out of nine drops. The lightweight, accurate Viper Strike seemed like an ideal weapon for drones, themselves good weapons for dirty little wars, and quickly went into service as the "GBU-44/B". The BAT smart submunition didn't prove to be what was needed at the time, but the Viper Strike proved a handy little glide bomb.
Viper Strike is intended for high-precision "top down" attacks on targets, particularly in urban or other built-up areas where collateral damage is a concern. Some Viper Strikes have been modified from such stockpiles of BATs as were accumulated before that program went on hold, with these weapons retaining the wingtip probes for the BAT acoustic sensors, but the probes have been deleted from new-build GBU-44/Bs.
The Air Force Special Operations Command is evaluating use of the Viper Strike with the Lockheed-Martin AC-130 Spectre gunship. Viper Strike improvements are being considered, such as a backup GPS-INS unit, a fragmentation belt for the shaped-charged warhead to add anti-personnel effects, and replacement of the current fixed "staring" laser seeker to a gimbal-mounted unit with a wider field of view.
* While the JDAM and WCMD projects have provided the US military with a degree of short range standoff attack capability, other programs have worked on weapons to attack targets at greater ranges. One of the most important of these, the US Navy and Air Force "Joint Stand Off Weapon (JSOW)" is now in operation and has been used in combat.
The JSOW project was initiated in 1986 under the initial name of "Advanced Interdiction Weapon System (AIWS)", the goals being a lightweight, low cost, fire and forget weapon with medium range and the capability to carry different types of warloads. A development contract was awarded to Texas Instruments in 1992. Texas Instruments was later acquired by Raytheon. Initial tests of JSOW began in 1994.
JSOW is an unpowered glide bomb with popout switchblade wings and a GPS-INS
navigation system. The weapon is smart enough to fly a preplanned path to
its target, making turns and hiding behind mountains. If the proper
preplanned launch point cannot be reached, the pilot can release it and, as
long as the target is within a pie-slice wedge on the cockpit display, let
the weapon determine its own flight plan. JSOW is light enough to be carried
by smaller attack aircraft such as the F/A-18, the F-16, or AV-8B Harrier.
AGM-154A JSOW:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 2.7 meters 8 feet 11 inches
length 4 meters 13 feet
total weight 475 kilograms 1,050 pounds
speed subsonic glide weapon
range at altitude 75 kilometers 47 MI / 40 NMI
_____________________ _________________ _______________________
The first version of JSOW to be developed was the "AGM-154A" or "JSOW-A",
which entered full-scale production in 1999. The AGM-154A carries 145
BLU-97A/B CEMs for use on "soft" targets. When the weapon makes its final
attack dive on a target, it blows off covers on either side of its boxy
fuselage, and a gas-inflated aluminum bladder scatters the submunitions out
the sides. The CEM submunitions produce armor-piercing, fragmentation, and
incendiary effects.
JSOW was introduced to combat in January 1999, during air strikes by US Navy strike aircraft on Iraqi air-defense sites, and was used in later combat actions. The results of these strikes exceeded expectations, and the US Air Force accelerated its efforts to get JSOW into full service. Some of the strikes demonstrated that JSOW wasn't able to correct for wind drift as well as desired, but Raytheon has implemented software fixes to correct this problem. A new multiple ejector rack has been developed to allow carriage of two JSOWs, or other weapons of similar size, on a single stores pylon. This will allow a small attack aircraft to carry four JSOWs instead of two.
* Both the US Air Force and the Navy considered an antiarmor version of the JSOW, the "AGM-154B" or "JSOW-B", with six BLU-108/B SFW submunitions, but it was cancelled. The Air Force decided that the WCMD-ER, described previously, was a better standoff antiarmor solution. The WCMD-ER could carry 10 SFW submunitions instead of six, could be developed quickly, and could leverage off the huge stockpile of 100,000 Tactical Munitions Dispensers built. The Navy decided they couldn't afford the AGM-154B on their own.
The US Navy has acquired a variant with a unitary warhead, the "AGM-154C", featuring a British-developed two-stage "Broach" penetrating warhead. It also features an imaging infrared seeker and datalink, compatible with the existing pylon-mounted control pod for the Navy Walleye glide bomb, to allow precision strikes on a target. The seeker, inherited from the SLAM-ER cruise missile, is capable of autonomous operation for "fire and forget" attacks. Low-rate production of the AGM-154C began in the summer of 2003, with operational introduction in 2005 on the F/A-18.
Raytheon has developed a low-cost JSOW with using a Mark 82 225 kilogram (500 pound) unitary warhead, with this variant designated the "AGM-154A-1" and mostly intended for the export market. A new "Block II" JSOW airframe is now being introduced, featuring an improved antijam GPS receiver and various simplifications to reduce cost. A "Block III" airframe is in development, featuring further cost reductions and a two-way datalink to provide strike assessment and midcourse mission changes.
A version of JSOW powered by a Williams International WJ-24 turbojet and named the "Griffin-36" was offered for the British Conventionally Armed Standoff Missile (CASOM) competition in 1996, but was not selected. Further JSOW developments include advanced ladar or millimeter-wave seeker, and a revived jet powered version. The baseline JSOW design actually includes space for an engine, so a powered version would not require major redesign of the airframe.
Turkey and Poland, ordered JSOW for their F-16s, with Singapore also ordering the JSOW for their new F-15s. Several other nations have expressed interest.
* A European standoff weapon system, developed by DASA of Germany, is available in both glide and powered forms. The best developed of this family of weapons is the "BombKapsel 90 (BK-90)" gliding cluster munition dispenser, developed primarily for the Swedish Air Force's JAS-39 Gripen fighter. It has been named "Mjoelnir", after the thunder god Thor's mighty hammer.
The Mjoelnir is a descendant of an MBB (ancestor of DASA) concept for a "Container Weapons System (CWS)" proposed in the 1980s. The idea behind CWS was to essentially take the core of the MW-1 cluster munitions dispenser, used by Luftwaffe Tornadoes, and fit it out with various modular nose, tail, and fin kits to allow it to be used as a short-range glide weapon, a long-range glide weapon with popout wings, or a rocket-propelled standoff weapon.
This scheme was apparently a bit too complicated, since the Mjoelnir follows
the same basic design configuration as the CWS but abandoned the modular
approach. The weapon is something like a "flying MW-1". The BK-90 contains
12 submunitions launch tubes on each side, with multiple submunitions
contained in each tube. It has a boxy fuselage with very stubby wings, as
well as tail fins on each corner of the fuselage box.
BK-90 MJOELNIR:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 1 meters 3 feet 4 inches
length 3.5 meters 11 feet 6 inches
total weight 600 kilograms 1,320 pounds
speed unpowered glide weapon
range at altitude 22 kilometers 14 MI / 12 NMI
_____________________ _________________ _______________________
The BK-90 is intended to be released at high speed and low altitude.
Essentially it allows a strike aircraft to "toss" the weapon onto a target,
with the weapon using INS navigation and terrain-following radar to navigate
into the target area. It can be also released from high altitude for more
standoff range, and has an optional GPS-INS capability for such long range
attacks. Toss range at low altitude is up to about 8 kilometers (5 miles),
while the range at high altitude is up to 22 kilometers (14 miles).
Once over the target, the BK-90 blasts its submunitions out of the ejector tubes, with the submunitions deploying small chutes to stabilize their descent. The dispersal pattern is up to about 250 by 400 meters (800 by 1,300 feet). There are two types of submunitions:
The BK-90 is being built and marketed in the US as the "Autonomous Free-Flight Dispenser System (AFDS)" by an American subsidiary of DASA named CMD. The AFDS has been evaluated by the USAF.
DASA also refers to the BK-90 as the "Dispenser Weapon System 39 (DWS-39)" because of its association with the JAS-39 Gripen, as well as "DWS-24", with the "24" designating the number of dispenser tubes. DASA offers other variants of the BK-90 of different sizes and weights: the 400 kilogram (880 pound) "DWS-16" with 16 tubes; the 1,000 kilogram (2,200 pound) "DWS-40" with 40 tubes; and the 1,400 kilogram (3,100 pound) "DWS-60" with 60 tubes.
* Alenia-Marconi of Italy has developed a new family of "Precision Guided Munitions (PGM)" conceptually similar to the US AGM-130, consisting of a rocket-boosted bomb with glide fins, midcourse guidance system with a command update capability, and a terminal seeker system giving a CEP of two meters (less than 7 feet). Cruciform fins are fitted to the tail, while a pair of small winglets are fitted to the nose.
The company offers two versions of the PGM, including the "PGM-500", which is unsurprisingly a 500 kilogram (1,100 pound) weapon sized for smaller fighters, and the "PGM-2000", which is a 2,000 kilogram (4,400 pound) weapon. Laser-homing, TV, and imaging infrared seekers are offered. The PGMs are intended for platforms such as the Dassault Mirage 2000, F-16, Northrop F-5, and BAE Hawk. The United Arab Emirates apparently obtained PGMs in the mid-1990s, naming the weapon the "Hakim".
* Israeli Military Industries (IMI) has developed a switchblade-wing glide dispenser named the "Modular Stand-Off Vehicle (MSOV)" that is similar to JSOW, and apparently based on the "Tactical Air Launched Decoy (TALD)" glider manufactured by the company. MSOV weighs 1,050 kilograms (2,300 pounds) and can carry a 675 kilogram (1,490 pound) load of submunitions, including antiarmor mines, runway penetrators, combined effects bomblets, and so on. It uses GPS-INS guidance. First trials were performed in 1998.
* Guidance systems developed for air-launched munitions had obvious applications to other munitions, such as artillery shells, and in fact, as mentioned, the design studies that led to the Paveway LGB started out as investigations into laser-guided artillery rounds. Following these studies, in the early 1970s the US Army initiated development of the "Cannon-Launched Guided Projectile (CLGP)", better known as the "M-712 Copperhead".
Copperhead is a laser-guided artillery round for launch from 155 millimeter (6.1 inch) guns. Martin Marietta conducted studies for the CLGP in the late 1970s, leading to a production contract in 1979. However, full development of a smart munition that could be fired out of an artillery piece, subjecting it to on the order of 10,000 gees of acceleration, proved difficult, and Copperhead didn't enter service until the mid-1980s.
Copperhead is 1.37 meters (4 feet 6 inches) long, of course is 155 millimeters in diameter, and weighs 62.4 kilograms (137.5 pounds). Maximum range is 16 kilometers (10 miles). It is fired like a conventional artillery round, and requires little special handling or training, though there are switches on the munition to specify trajectory and laser designation options.
On firing, a thermal battery and a timer inside the Copperhead are activated, a gyro is spun up, tailfins pop open, and the laser seeker begins to scan. The seeker acquires laser reflections from a target as the munition falls toward the earth, and then fins pop open from the midbody to guide the Copperhead into its target, which is destroyed by the shell's hollow charge warhead. Work was performed on a Copperhead variant with a radar-homing seeker, but this version did not go into production.
* In the 1990s, the US military's infatuation with GPS led to development of a new generation of GPS-guided artillery shells, with the designation "Extended Range Guided Munition (ERGM)". Two similar shells are being developed by Raytheon, including the US Army's "XM-982" 155 millimeter munition, and the US Navy's "EX-171" 127 millimeter (5 inch) munition.
The Army and Navy weapons have similar electronics, though the Army munition uses a silicon INS while the Navy munition uses a fiber-optic gyro INS. Of course, the shell size is different, and the Navy's 1.5 meter (5 foot) long EX-171 has a rocket booster that gives it a maximum range of 100 kilometers (62 miles). ERGM has pop-out tail and nose fins for guidance, and has a 20 meter (66 foot) CEP. ERGM will have an secondary seeker mode where it will home in on GPS jammer transmissions, giving it an aggressive antijamming capability. ERGM's baseline configuration is as a cargo shell, with 72 "EX-1" submunitions, a derivative of the US Army M80 DPICM. Initial firing of an "all-up" ERGM round was in June 2002.
Efforts have been put into developing cargo shells with smart submunitions. The US Army worked with Aerojet to develop such an munition with the designation of "M898 Sense And Destroy Armor (SADARM)". SADARM consists of two submunitions in a 155-millimeter shell. As the shell descends into the target area after launch, it ejects the two submunitions, which then release a ballute to stabilize themselves, and finally release parachutes to slow their descent. Each submunition carries an infrared and a millimeter-wave sensor, and as the submunition descends it scans the area below it for the signature of an armored vehicle. On targeting an armored vehicle, the submunition fires an explosively-formed projectile into the thin-skinned top of the vehicle. SADARM went into production in 1996. Over a hundred were expended during the US invasion of Iraq in 2003 and the munition was regarded as more effective than expected.
The German GIFS "SMART-155" munition features a multimode seeker featuring an IR sensor, microwave radar, and microwave radiometer; stabilizing ballute and fins, and braking parachute; and explosively-formed kinetic-energy penetrating warhead. Initial live-fire tests of the SMART-155 were performed in 1996, and is now in service with the German, Swiss, and Greek armies.
* Bofors of Sweden has developed the "Strix" smart mortar round, which fires a single smart munition. The Strix looks much like a conventional mortar round, with tailfins that unwrap from the end of the round. The Strix has been in service with the Swedish Army since 1994, and has been ordered by the Swiss Army. Bofors developed a 155-millimeter shell, the "BONUS-155", with two such submunitions, but there's no indication that it has gone into production.
The Strix is the only Western smart mortar round to be introduced so far. The US Army has worked on a smart round for the 120 millimeter mortar, with the designation "M395 Precision Guided Mortar Munition (PGMM)", in the form of a hollow-charge gliding munition with popout fins and a laser seeker. The program has been protracted, though for the moment it seems to be on track.
There has been a debate on the usefulness of smart mortar rounds. Critics have suggested that the limited range and destructive capability of mortar rounds make them too limited to make adding a relatively expensive seeker worthwhile. Advocates have replied that the PGMM's glide capability extends its reach by an order of magnitude compared to a conventional mortar bomb, and that a large munition isn't needed for a pinpoint attack -- indeed, a larger weapon may just cause more collateral damage.
There are a number of other smart shell / mortar round development efforts in the works in the West, but again, it is worthwhile to take them with a grain of salt. These programs seem to pop up in the press and then disappear again, sometimes finally being cancelled, or sometimes emerging again in a different form.
* The Soviets developed their answer to the US Copperhead laser-guided artillery projectile, the "Krasnopol" series of munitions. As with Copperhead, it was to be used to perform precision strikes on hard targets, with the target laser-designated by reconnaissance assets or special ops teams. Work on the Krasnopol munition was begun at the KBP organization in Tula in the late 1970s. The munition was to be fired out of a standard 152 millimeter howitzer, giving it a range of 10 to 20 kilometers (6 to 12 miles). The Soviets found developing a guidance system that could withstand thousand of gees as troublesome as did the Americans, and the munition didn't begin to reach service units until 1987.
The Krasnopol system is built around a laser-guided projectile, which is 1.3 meters (4 feet 4 inches) long, with the rest of the system consisting of fire-control apparatus and a laser target designator. The munition will not fit into automatic loaders and has to be hand-loaded, but the operational cycle takes only about 90 seconds. The fire-control system is linked to the laser designator to ensure that it is only turned on about ten seconds before impact, otherwise the munition will try to drop into a flat trajectory to the target, robbing it of kinetic energy and range. During midcourse flight, the munition is guided by an INS. The target has to be within about a kilometer from the precalculated impact point. Kill probability is about 90% in clear weather conditions.
A second-generation version of the munition, the "Krasnopol-M", was developed in the 1990s. It reduced the length to 95 centimeters (3 feet 1.4 inches), allowing it to be used in automatic loaders, though it has shorter range. The Krasnopol-M is available in both 152 millimeter and 155 millimeter variants. It has been exported to at least twelve nations, and Russian forces have used it to fight the insurgency in Chechnya.
Tula KBP also sells a 122 millimeter laser-guided munition, the "Kitolov-2", which is derived from the Krasnopol, as well as a comparable 120 millimeter laser-guided mortar round, the "Kitolov-2M". These have not been fielded by the Russian military and seem to be for the export market.
