Bunker Busters
IN THIS SECOND INSTALLMENT IN THE SERIES, SOTECH LOOKS AT SOME OF THE OTHER OPTIONS AVAILABLE TO SOF WHEN THEY NEED TO KNOCK HARD.
A November 20, 2006 sources sought announcement from the U.S. Army Program Manager for Close Combat Systems in conjunction with the U.S. Army Research, Development, and Engineering Command, Armament Research, Development, and Engineering Center, highlighted an ongoing military interest in bunker buster technologies.
Part I of this series highlighted several representative systems developed for or employed in this role by U.S. forces. Those included TOW missiles modified with specialized bunker buster warheads, the Javelin missile and the 84 mm Carl Gustaf M3 Multi-Role Anti-Armor Anti-Personnel Weapon System (MAAWS).
In addition to these platforms, a variety of man-portable, shoulder-fired systems have been developed and/or modified in recognition of the bunker busting needs of current battlefields. Representative samplings of these myriad activities include modifications to the M72 LAW, the SMAW series, the AT4 and Predator.
LAW
The M72A3 Light Anti-Armor Weapon (LAW), manufactured by Talley Defense Systems, is a lightweight, self-contained, antiarmor system consisting of a 66 mm rocket packed in a compact, disposable launcher. It is man-portable and may be fired from either shoulder. The launcher, which consists of two tubes, serves as a watertight packing container for the rocket and houses a percussion-type firing mechanism that activates it. The M72 LAW is capable of penetrating half a foot of armor, with an effective range of up to 220 meters.
Late in 2006, Nammo AS, (Raufoss, Norway) and Talley Defense Systems (Mesa, Ariz.) signed an agreement, whereby Nammo acquired 100 percent of Talley. The M72 LAW was initially developed in the United States and was licensed to Nammo in the early 1960s. Although initially designed for attacking armored targets, representatives at Nammo note that the M72 has recently been modified with expanded capabilities.
Nammo’s Terje Homb points to the M72 Enhanced Capacity (EC) design as one example. The EC model, which was qualified by the Norwegian Army in 2006, incorporates improvements to the warhead—including the use of PBXW-11 IM type explosive—as well as launcher improvements ranging from weight reductions through the use of a carbon fiber inner tube to increased hit probability through the use of an axial trigger and reflex sight.
The new reflex sight for the M72 provides improved operability day and night. The sight, which can be used by both right- and left-handed operators and with or without night vision goggles, features a ballistic reticle with moving target aim point. Reticle illumination is provided either by daylight or external light sources.
Other new M72 improvements that position the system in the bunker buster category are incorporated in the M72 Anti- Structure Munition (ASM) Reduced Caliber (M72 ASM RC).
Designed for urban warfare applications, the M72 ASM RC combines the launcher improvements found in the M72 EC with a reduced caliber warhead (for enhanced penetration) and an enhanced blast explosive. Other improvements include a new dual safety fuze.
“It is a dual mode fuze with a manual switch between short delay—wall breaking— and long delay—penetration and detonation inside the target,” Homb said, adding, “The M72 ASM RC is under development and expected to be qualified by the end of this year.”
SMAW-NE
Other recent bunker buster efforts involve Talley’s Shoulder-launched Multipurpose Assault Weapon (SMAW), which has been employed by the United States Marine Corps for more than two decades.
Warhead versatility of the SMAW series has recently been expanded from follow through grenade (FTG), common practice round (CPR), high explosive dual purpose (HEDP) and high explosive anti-armor (HEAA) to include a new novel explosive (NE) design, described as a “dual purpose, dual safe, self discriminating warhead for urban destruction.”
Although the SMAW-NE functions like the original SMAW HEDP round, the new round contains a much larger explosive fill: four pounds of PBXN-113, an aluminized high explosive composition with similar characteristics to the 2.4-pound load of Aluminized Composition A3 fill in the SMAWHEDP.
Although originally developed with an eye toward application in the caves of Afghanistan, the use of delayed fuzing allows the SMAW-NE warhead to detonate after penetrating light structures. The expanded capability has reportedly been proven during urban combat operations in Iraq.
PREDATOR/SRAW-MPV
Other post-9/11 bunker buster activities involved the “Predator” shoulder-fired, short-range anti-armor missile. Developed by Lockheed Martin for the Marine Corps, the Predator features a portable, inertiallyguided, point-and-shoot system designed to defeat advanced armor targets at ranges from 17 to 600 meters. The complete system weighs less than 22 pounds and uses a fly-over, shoot-down trajectory to attack tanks at their most vulnerable point.
Predator entered low rate initial production in early 2002.
However, the bunker busting exigencies of the new millennium soon led to efforts to convert the anti-tank missile for urban assault applications. Renamed the Short-Range Assault Weapon-Multiple Purpose Variant (SRAW-MPV), the new urban assault missile has a multiple-purpose blast warhead, enabling it to defeat a variety of targets such as buildings and bunkers, as well as light-armored vehicles.
In late May 2005, Lockheed Martin announced that it had responded to the urgent warfighter request with the delivery of 400 SRAW-MPV rounds to the Marine Corps.
“The conversion of Predator from a topdown anti-armor weapon to a direct-fire urban assault weapon was prompted by the need for fire-from-enclosure assault weapons, which has become paramount to support current actions,” said Andy Hawkins, SRAW-MPV program manager at Lockheed Martin Missiles and Fire Control. “Other current short-range assault weapon systems cannot meet the requirement.”
“This variant of the Predator weapon system is uniquely suited to the urban warfare environment that is prevalent in military operations today,” Hawkins added. “The SRAW-MPV is the only short-range soft-launch assault weapon in the world. It can be safely fired from buildings with single hearing protection, which protects the gunner by minimizing exposure to enemy counter-fire. In addition, its pointand- shoot, fire-and-forget inertial guidance system minimizes gunner operations and corrects for in-flight disturbances such as cross-wind.”
A recent check on program status drew the following response from a Lockheed Martin spokesperson: “All of the government- funded production equipment has been returned to government control. It’s our understanding that there is testing still ongoing with the Marine Corps to demonstrate the system’s effectiveness, but there are no plans to re-open production at this time or to offer this weapons system to the marketplace. Lockheed Martin is exploring several new concepts to re-enter the shoulder-fired market, available in the near term.”
SMAW-D
The SMAW-D [disposable], designated M141 Bunker Defeat Munition (BDM), represents another response to urgent warfighter requests.
The M141 BDM is a shoulder launched munition fielded to meet an urgent U.S. Army Forces Command requirement to fill an identified bunker buster void in the Army inventory. The man-portable system is highly effective against targets including fortified positions (earth and timber bunkers) and is also capable of breaching masonry walls and neutralizing light armored vehicles at ranges of 15-500 meters.
According to Talley Defense, the SMAWD is a single shot, disposable version of combat-proven U.S. Marine Corps’ shoulder- launched multipurpose assault weapon with the same massive target over-match effects against field fortifications, urban structures, and lightly armored vehicles as the SMAW. It can breach 8-inch reinforced concrete walls and 12-inch triple brick walls.”
In addition to satisfying the urgent needs, late 2006 saw the release of the sources sought announcement noted above, explaining that PM-CCS RDECOMARDEC were seeking sources for a bunker defeat munition (BDM). The BDM is an 83 mm handheld, single shot, disposable, stand-alone, direct fire munition designed to defeat earth and timber bunkers. It is manportable, self-contained, air-jumpable, air-deliverable (by pallet), and contains an interface for attachment of various night vision and aiming devices. Specifically designed for the close fight on urban and complex terrain, the BDM is quickly trained and employed in a manner similar to the AT4. As an expendable round of ammunition, the lightweight (not to exceed 17 pounds), compact (not to exceed 40 inches), disposable BDM provides a highly lethal capability delivered in a safe, easy to operate weapon that can be readily transported. As a stand-alone, selfcontained munition, the BDM requires no maintenance, nor dependence on other systems; however, its ease of use and lethality greatly enhances combat effectiveness.
AT4
Referenced in the sources sought announcement, the M136 AT4 is the Army’s primary light anti-tank weapon. It is a recoilless rifle used primarily by infantry forces for engagement and defeat of armor threats. The rifle’s design permits accurate delivery of an 84 mm high explosive antitank (HEAT) warhead providing excellent penetration capability and lethal after-armor effects. The system weighs approximately 15 pounds and consists of a free flight, finstabilized rocket packed in an expendable, one-piece, fiberglass-wrapped tube. The launcher is watertight for ease of transportation and storage. The M136 AT4’s warhead uses an extremely destructive, 440-gram shaped-charge explosive that can penetrate more than 14 inches (35.6 cm) of armor.
Recent system enhancements have optimized the AT4 for urban combat.
“The AT4 Combined Space (CS) HEAT RS—reduced sensitivity—has been in use by USSOCOM for one and a half to two years,” says Leif Jilsmo, product director for ground combat systems within Saab Bofors Dynamics AB, Karlskoga, Sweden. “That provided a confined space capability, so they can use it from inside small rooms.” As described in a recent government procurement solicitation, “The AT4-CS will provide the U.S. Army and special operation forces with the capability to defeat medium (e.g. BMP-3) armored targets encountered in urban combat environments. The capability of the AT4-CS to be safely fired from confined (or enclosed) spaces will provide field commanders and soldiers with an effective capability that will increase mobility, flexibility in the application of force and lethality by significantly increasing engagement locations while limiting exposure to gunners. The U.S. Army, in cooperation with USSOCOM, intends to procure the AT4-CS RS weapon system for use in urban warfare.
“Hopefully the [larger] Army will also have it within a couple of months or so,” Jilsmo added. “They are just waiting for the safety release.”
According to Jilsmo, the “reduced sensitivity” designation means that the round does not completely meet all of the requirements for “insensitive munitions” (IM) designation but still satisfies many, as in the PBX explosive warhead.
“It’s a pre-loaded system,” he said. “So if you ignite the propulsion system it does not meet IM, so it is not ‘fully IM compliant’ but we have certainly taken a step in the right direction.”
Looking toward the future, Jilsmo described some of the ongoing efforts surrounding the AT4-CS Anti-Structure Tandem (AST).
In its April 2005 sources sought announcement, PM-CCS, in conjunction with ARDEC, Picatinny Arsenal, N.J., called for improved non-developmental items (NDI) or near-NDI warheads and fuzing for the 84 mm AT4-CS weapon system providing U.S. Army and SOF the ability to defeat personnel behind complex targets (to include reinforced concrete and brick walls) being encountered during urban combat environments. The U.S. Army and U.S. special operations forces both utilize the M136 AT4 weapon and AT4-CS. The U.S. Army, in cooperation with the USSOCOM, intends to conduct test and evaluation of improved warheads with the AT4-CS weapon that will increase its operational effectiveness in urban warfare.
In late September, the Army announced its intention to solicit and negotiate with Saab Bofors Dynamics AB for a four month contract for the purchase of 30 AT4-CS AST weapon systems, plus a 14 month option for the integration of the Multi-Role Anti-Armor Anti-Personnel Weapon System (MAAWS) Multi-target (MT) round to the AT4 and the purchase of 30 AT4-CS MTs.
“The AT4-CS AST is a new AT4-CS version that will undergo company qualification in the middle of this year,” Jilsmo explained. “So we are just now producing components for that qualification. So we have a company qualification this year and the time schedule is that, if everything goes well, the U.S. Army will qualify in the beginning of 2008.”
“The AST will provide a lot of things,” he continued. “It has two modes in the warhead: one short delay and one long delay. And with the short delay you detonate the charge in the wall, so you can open up a corridor or a new entrance. And if you put in a long delay it will pass the wall and detonate behind it.”
“And it has a ‘novel explosive’ in the main follow-through charge,” he added. “Not in the precursor but in the main charge. And it uses PBX explosive as well.”
UAW
Along with the plethora of options designed to support the urgent needs of today’s warfighters, military planners are looking forward to new systems to meet tomorrow’s bunker busting requirements.
One such vision is found in descriptions of the Urban Assault Weapon (UAW) presented by PM-CCS.
Describing UAW as “the Army’s next generation shoulder-launched munition,” one recent program overview notes, “It is designed for use by the Objective Force Warrior to dominate complex and urban terrain in order to fight and finish the enemy. UAW will also contribute to survivability by enabling the soldier to engage targets from protected positions without exposing himself to enemy fires and effects.”
“The UAW will be a disposable, shoulder- fired weapon capable of defeating light armored vehicles and personnel within bunkers or behind masonry and brick walls,” it continues. “It will not require any maintenance or a dedicated gunner, and will use existing or future night sights. The UAW will replace the M72A3 LAW, M136 A-4 and M141 Bunker Defeat Munition.” ♦