Multiwarhead Tomahawk Could Strike Many Targets

Spin-Offs May Affect Other Munitions as Engineers Leverage Sub-Warhead Technology

By HUNTER C. KEETER
Associate Editor

NAVAL SURFACE WARFARE CENTER, DAHLGREN, Va.--An advanced version of the Tomahawk Land Attack Missile (TLAM), armed with seven warheads rather than one, could dramatically improve the Navy's land attack capability while helping to maintain the competitive edge of this key weapon, according to officials here and a senior congressional analyst. As demonstrated in conflicts such as Operation Iraqi Freedom, the military requires the ability to strike precisely at numerous targets in complicated terrain. Improving the capability of mainstay systems such as TLAM is one way the Navy plans to get more from investments already made in long-range striking power.

The Tomahawk missile long has been the Navy's premier land attack weapon. Nearly 300 missiles were launched in Operation Desert Storm in 1991, and more than 700 were launched against Saddam Hussien's army in Operation Iraqi Freedom by attack submarines and surface ships. Built by Raytheon Company's Missile Systems Unit, Tucson, Ariz., the 20-foot cruise missile, guided by terrain comparison and digital scene mapping computer software and Global Positioning System satellites, usually is armed with a 700-pound titanium blast-fragment warhead.

The Navy now is buying an upgraded version of the TLAM, known as Block IV, or Tactical Tomahawk. The new TLAM is expected to offer increased range, and more flexible guidance, as well as the ability to loiter over a target area after being launched from a ship or submarine. Using coded radio messages, the missile could be re-directed to attack a new target.

Here at Dahlgren, ordnance designers hope to take the new TLAM's warhead capability one step further. Under a project titled Multiple Responsive Ordnance (MRO) the Tomahawk could be fitted with seven independent warheads, each with its own guidance system and capable of acting independently or together as a single weapon. The TLAM could release some of its payload to attack opportune targets on the way to destroy a site programmed into the missile's memory banks before launch.

Walter E. Hoye, principal scientist for ordnance systems, told Sea Power the MRO concept could build upon the Tomahawk's proven capability to penetrate and destroy hardened structures, such as enemy bunkers. In the near future, several Tomahawks could be launched to destroy a target and, finding their objective already eliminated by earlier rounds, follow-on missiles could be diverted to use their independently programmable warheads to kill additional targets.

"Here is an elaboration or more advanced concept for implementing a long-standing idea of having the TLAM carry multiple munitions," Ronald O'Rourke, a senior analyst with the Congressional Research Service, told Sea Power. "The MRO project would allow the Tomahawk to take better advantage of improvements in precision guidance and small munitions that are becoming available to the manned aircraft community. This has the potential to make the Tomahawk more cost effective in the sense that a single weapon could attack multiple targets."

Hoye and other scientists at Dahlgren's weapons lab point to the difference between sub-warheads and sub-munitions. A sub-munition is generally thought of in association with cluster bombs or other types of weapons that may be able to spread unguided mine-like, or grenade-like, objects around a target area. A sub-warhead, when it separates from the main weapon, would be independently targeted and guided to its goal.

"The Tomahawk is getting away from some of the smaller sub-munitions because these have been found not to be as effective as desired," David Cooke, head of Dahlgren munitions program's strike group, told Sea Power. "Under the MRO project, if you needed a unitary warhead, you could keep the individual sub-warheads in the package and take them all into the target. But each of the sub-warheads could have its own guidance system and could be released at some earlier point, and they would know to go to specific targets."

The Tomahawk program also is under pressure from new concepts such as the Affordable Weapon, being developed by the Office of Naval Research, O'Rourke noted. With the newest version of TLAM expected to cost half a million dollars, the Affordable Weapon cruise missile, offering a price tag closer to $50,000 per unit, has the attention of some in the Navy and Congress. The Affordable Weapon system is not expected to have the range or payload capacity of Tomahawk, but improving the ability of the more expensive missile precisely to strike at multiple targets may go a long way toward maintaining TLAM's competitive edge, according to O'Rourke. Last year, the Office of Naval Research continued its relationship with the San Diego-based firm, International Systems, under a $25 million contract operating through April 2004.

The Navy's efforts to improve current cruise missile capability, whether through advanced warhead concepts such as the one conceived at Dahlgren, or the TLAM's competitor, Affordable Weapon, fit into an overall plan to boost striking power from the sea to shore. With ships and submarines being improved to carry large volumes of weapons, such as the SSGN conversion plan to refit four Trident nuclear ballistic-missile submarines to carry as many as 154 TLAMs, added capacity in the weapons themselves could further amplify the conventional striking power of tomorrow's fleet.

Spin-off technology from efforts such as Dahlgren's MRO for TLAM could benefit other systems. The Navy is considering sub-warhead technology's application for the Joint Stand-Off Weapon, a glide bomb launched by manned aircraft, and for the CBU-97 sub-munitions bomb. The Air Force's Conventional Air Launched Cruise Missiles, and the Army's Tactical Missile Systems, are examples of products that could also employ sub-warhead technology.

Meanwhile, other efforts are underway at the Dahlgren weapons lab. One of those is a project to reduce the collateral damage of a conventional blast-fragment warhead on a bomb or missile. Under a project titled Dense Inert Metal Explosive (DIME), Dahlgren scientists are studying the effects of adding dense metallic particles, such as tungsten, to a high-explosive chemical mixture. According to tests performed at Eglin Air Force Base, Fla., the detonation of such a mixture shows increased deadly effects at a slightly greater range from the center of blast, contrasted with conventional explosives. But the DIME mixture's lethality falls sharply a short range from the blast center, reducing the chance of destroying something other than the intended target.

The DIME concept is particularly interesting to the Navy for use in urban areas. Cook explains: "a normal blast-frag warhead has high-explosive putting fragments out. You get a high probability of kill, but it lasts for quite a distance. That means that if you were to drop a blast-frag weapon in the middle of a city block you would be doing a lot of damage in an urban area," which is not always the effect U.S. forces want to achieve. With DIME, the blast effect equals that of a blast-fragment weapon, but the chances of collateral damage appear to be substantially less, said Cook. Another series of DIME technology tests is planned later this year at Eglin Air Force Base. *