* Much of the technology incorporated into modern air-launched munitions turns out to be applicable to artillery as well. This chapter discusses artillery "cargo shells" -- cluster munitions, more or less -- and "smart" guided shells.
* Cluster munition artillery shells are also in service; although they are not air-launched munitions, they are very similar to CBUs and so worth commenting on here. They are generally referred to as "cargo munitions" or "cargo shells", a broad term for any artillery shell that dispenses a payload instead of carrying an explosive charge.
The history of the concept is obscure. The idea has probably been around for as long as air-dropped cluster munitions, but trying to trace out its evolution is troublesome. One of the earlier cargo munition to carry a load of submunitions, usually called "grenades" in this context, was the US Army "M483" 155-millimeter round. It is a "separate loading" munition, fired with bagged powder charges instead of as an integrated cartridge, and loaded with 88 "Dual Purpose Improved Conventional Munition (DPICM)" antipersonnel / antiarmor impact-fuzed grenades resembling large flashlight batteries.
The grenades are of straightforward configuration, with a hollow charge in a metal case and a streamer that each grenade deploys after the M483 case bursts open. There are two types of grenades: 64 "M42" grenades with prefragmented cases forward, and 24 "M46" grenades in the rear, with heftier non-prefragmented casings so they can handle the shock of firing. The shell can be fitted with a charge to detonate all the grenades at once without dispersal; this is used to register fire on targets, since a standard unitary shell doesn't have the same flight characteristics. Some sources also mention a 203 millimeter (8 inch) cargo shell, the "M404" with 104 grenades, and a more modern 203 millimeter follow-on, the "M509" with 195 grenades, but details are very hard to find.
* As long as an artillery shell had been developed to disperse grenades, there was no particular reason why the same basic technology couldn't be used to disperse other offensive payloads, leading to the 155-millimeter "Area Denial Antipersonnel (ADAM)" mine shell and the "Remote Anti-Armor Mine (RAAM)" shell:
* The M483 family appears to have become something of a standard for Western armies. The M483 has since been followed by the "M864", which is a "base burn" projectile. An artillery shell leaves turbulence in its wake that can rob the projectile of energy, reducing its range; a base burn projectile features a pyrotechnic load in the base of the shell that generates gas to drive out the turbulence, substantially enhancing range. Fit of the base burn system meant that the number of grenades had to be reduced to 70 from 88, with 46 M42 grenades and 24 M46 grenades.
* Cargo rounds have been developed for other weapons besides the 155 millimeter gun. The US Army has obtained a 105-millimeter cargo round, carrying 42 "M80" DPICM grenades, similar to the M42 but with an improved fuzing system. This is a cartridge-type round, not requiring a separate propellant load, and there are two variants: the "M915" with a large charge for long range and the "M916" with a small charge for short range. Cargo rounds have also been developed for the 107 millimeter (4.2 inch) mortar and 120 millimeter mortar, though details are obscure.
Of course, cargo rounds have been developed elsewhere. Rheimetall of Germany developed the 155-millimeter "DM642", a more aerodynamic cargo shell with greater range than the M483. It carries 63 grenades, again much along the lines of the M42. The DM642 has since been followed by the "Rh49", which is an extended-range base bleed munition with the load reduced to 43 grenades. It is a sure bet that the Russians have a complete line of cargo shells, but details are also very hard to find.
Cargo shells are a fairly standard weapon in modern warfare. The M483 was used in the 1991 Gulf War, as well as in the invasion of Iraq in 2003, when it was joined by the M864 base burn shell; the M864 was available at time of the Gulf War, but operational procedures hadn't been implemented for its use. During the last days of the Israeli fight with Hezbollah militia in southern Lebanon in the summer of 2006, Israeli artillery plastered the region with large numbers of cargo shells. The Israelis apparently produce copies of American cargo shells but have also developed their own, in 155 and 105 millimeter formats.
BACK_TO_TOP* Guidance systems developed for air-launched munitions had obvious applications to other munitions, such as artillery shells, and in fact, as mentioned earlier 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 "M712 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.
From the 1990s, the US Army also worked to develop a precision munition for 120 millimeter smoothbore tank guns. The effort went in fits and starts, finally stabilizing in 2007 with award of a contract to Raytheon for development of the "XM1111 Mid-Range Munition (MRM)". Guidance will be provided by an imaging infrared sensor in combination with a laser seeker.
* From the 1990s, the US military's infatuation with GPS led to introduction of GPS-guided artillery shells. Raytheon has developed the "Excalibur / XM982" 155 millimeter munition for the US Army. Raytheon worked on the program with assistance from Bofors of Sweden, a BAE Systems subsidiary.
The munition has a pop-out tail and nose fins for guidance, and was designed with a 20 meter (66 foot) CEP. Excalibur has a secondary seeker mode to home in on GPS jammer transmissions, providing aggressive antijamming capability. Initial firing of an "all-up" round was in June 2002, with the Army introducing the XM-982 into service in Iraq on a combat evaluation in 2006. The munition proved all that was expected of it, with a CEP of 4 meters (13 feet) 92% of the time, and the Army is enthusiastic about ramping up production. Other US guided shell efforts are in progress:
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 judged 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 has been obtained by the Australian, British, German, Greek, and Swiss armies.
* Bofors has developed the "BONUS-155" smart artillery round, which is comparable to SMART-155, carrying two smart submunitions. The BONUS-155 is now in service with the Swedish and French armies, and work is underway for an improved follow-on with a better seeker and more insensitive warhead. Bofors has also developed the "Strix" smart mortar round, which carries a single BONUS 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.
The Strix is the only Western smart mortar round to be introduced so far. The US Army has sponsored development by ATK of 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, but the PGMM has seen operational use in Afghanistan.
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, an important consideration in urban combat.
The small size may also be an advantage in other contexts. General Dynamics has tested a "roll controlled fixed canard (RCFC)" fuze that can be screwed into 81 millimeter mortar rounds in place of a traditional fuze, providing them with GPS-INS guidance using moving fins on the fuze body. At the outset, the RCFC fuze was defined for use of 81 millimeter rounds as an air-dropped munition, the small size of the mortar round making it appropriate for small UAVs. A standard 81 millimeter mortar round with fuze weighs 4.1 kilograms (9.1 pounds); using the RCFC fuze raises the weight to only 4.9 kilograms (10.8 pounds). There is the minor disadvantage that mortar rounds aren't designed for airdrop -- they don't have lugs -- requiring the development of a clamp-type UAV stores carriage system.
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 canceled, 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.
BACK_TO_TOP* I never really planned to write this document. I found an article on laser-guided bombs in AVIATION WEEK in October 1996. I wanted to slum a bit and throw together something quickly to keep up my monthly production of aviation documents. This led to a short document on LGBs, and then a few other documents on other guided weapons, and one thing led to another. Finally, after a number of years I decided to do a job of it, which led to a great deal of frustrating detective work. The first revision was released in 1999, with further revisions following every year or two.
* Sources for this document include:
I acquired all the back issues of WORLD AIR POWER JOURNAL and WINGS OF FAME in mid-1999, and currently subscribe to the successor to these two publications, the INTERNATIONAL AIR POWER REVIEW. I have used the my archive of these magazines as a major source for this document. I have not generally cited specific issues, since I found tiny (and often frustratingly terse) bits and pieces of materials on air-launched munitions in a large number of them.
I found various old volumes of JANE'S ALL THE WORLD AIRCRAFT in local libraries and uncovered various fragments of information in them as well. Alas, JANE'S also tends to be terse, and in the last decade or so air-launched missiles were relegated to a specific JANE's on missiles instead of being part of the aircraft publication. Since this volume is unbelievably expensive, it is hard to find.
I performed many searches of the Web to see if I could find anything of use. This was a major scavenger hunt that yielded many bits and pieces of information, though there were a few more substantial websites as well. One of the most interesting, as mentioned, was the "English Bombs Of World War II" page, which was a neat little article with nice details on Barnes Wallis and his bombs. The Federation Of American Scientists website contains many documents on specific munitions, plus a little tutorial named "Bombs For Beginners". Many minor details were also obtained from the MISSILES.INDEX website in Japan.
The Boeing and USAF Eglin websites were good sources for many of the new smart weapons. The website for the USAF Museum at Wright Patterson Air Force Base in Ohio was also useful. When I visited the museum a few years back, I was surprised to find the obscure US glide bombs well represented among the exhibits. Then I learned most of them had been developed there. "Duh."
* The individual articles on which this document is based were initially released with the following titles, in the following order:
* Revision history:
v1.0 / 01 nov 99
v1.1 / 01 jan 00 / Polishing and minor updates.
v1.2 / 01 feb 01 / Incremental upgrade with refinements.
v1.3.0 / 01 feb 02 / Incremental upgrade with format changes.
v1.4.0 / 01 aug 02 / Incremental upgrade.
v1.4.1 / 01 dec 02 / Rewrite of laser pod material, other changes.
v1.5.0 / 01 nov 04 / Yanked cruise missiles, general update.
v1.6.0 / 01 nov 06 / Cleanup and simplification.
v1.7.0 / 01 nov 08 / General update and cleanup.
v2.0.0 / 01 may 10 / Quick reorganization, cut back targeting pods.
v3.0.0 / 01 apr 12 / Cut antiship missiles, put in separate document.
Cancellation of NGM.
BACK_TO_TOP
