Engineer Bulletin February 1998

The Grizzly: Mobility Support for Force XXI

By Lieutenant Colonel Donald P. Kotchman, Wesley I. Glasgow, and Lieutenant Colonel Harry Greene

"The capability to rapidly breach obstacles has evidenced almost no improvement since World War II. Techniques in use are conceptually the same as those used in the 1940s."

Headquarters, U.S. Department of the Army,
After Action Report for Operation Desert Storm, 1991

Changes are on the horizon. With the fielding of the Grizzly in FY 2004, the U.S. Army will have a survivable, mobile, complex-obstacle-reduction system. These capabilities do not exist in any army today and respond to a growing threat.


The Challenge

As we look to the 21st century and Force XXI operations, our Army expects to have a technological advantage in information and weapons over any potential adversary. To counter our advantages, adversaries will attempt to use asymmetric threats, such as obstacles, which cost little but provide them great benefits.

Obstacles are expected at all levels of conflict, and obstacle technology is improving and proliferating. Rapid ditching machines; artillery-, rocket-, and air-delivered mines; and ground minelayers are available on world markets. They allow our adversaries to rapidly emplace complex obstacles, giving friendly forces little or no warning of their existence. Mine fuzings for hand-emplaced and scatterable mines are moving toward greater sophistication and lethality that overmatch our current reduction assets. A low-cost fuze upgrade to a World War II-era mine (millions of which are available around the world) transforms a simple, pressure-fuzed mine into a full-width, multisensor mine capable of killing our $6 million tanks. We can expect an increase in enemy countermobility operations as a counter to our superiority in information and weapons technology.

"Breaching a complex obstacle covered by enemy fire is the toughest attack mission a unit can get."

General Frederick Franks Jr. (Retired)
Commander, VII Corps
Operation Desert Storm


Preparation for breaching operations traditionally includes the following requirements:

The complex nature of these requirements necessitates deliberate breaches for all but the most simple obstacles, with a corresponding loss of tempo.

Executing a breach is difficult today due to the large number of vehicles involved and the synchronization required for success. For example, approximately 30 percent of the tank assets in the combined arms battalions of Force XXI will be dedicated to carrying rollers and plows to support breaches. The smaller, more agile units of Force XXI will use information to dominate maneuver. The ability of potential adversaries to rapidly emplace increasingly destructive and effective minefields and complex obstacles mandates new ways to execute breaches to enable dominant maneuver.

Operational Advantage

Today's methods of defeating complex obstacles require a complex operation involving several types of specialized equipment, none of which offer the versatility, mobility, or survivability of the Grizzly. Using current systems, the task force commander and engineer must orchestrate a variety of reduction assets to conduct breaches. Since each complex obstacle is unique, each breach requires employment of the various assets in a different order, effectively preventing the use of battle drills, complicating task organization, and mandating the requirement for lengthy reconnaissance and rehearsals.

Consider a complex obstacle consisting of wire, minefields, and antitank ditches. After completing the preamble to the breach (reconnaissance, planning, assembly of equipment, etc.), the breach begins with removing the wire, typically accomplished by soldiers using wire cutters, bangalore torpedoes, or an M58 mine-clearing line charge (MICLIC). Their efforts may be complicated by antipersonnel mines and fires. After the soldiers create a lane in the wire, they fire a series of MICLICs into the minefield. The number of MICLICs needed depends on the linear depth of the minefield. When the first MICLIC is fired, the breach site is immediately visible to the enemy. After each MICLIC is fired, the lane must be proofed, typically with a mine roller or plow mounted on an M1 tank. Using current allocation rules and the decreased size of the Force XXI combined arms battalion, 30 percent of the combat vehicles are required to push either rollers or plows. The resulting lane is cleared only along the width of the M1 tank tracks, requiring that additional passes or sappers improve the lane for follow-on forces.

The presence of antitank ditches adds complications since neither tanks equipped with battalion countermine sets nor MICLICs are effective against this obstacle. Either an armored combat earthmover (ACE) or an armored vehicle-launched bridge (AVLB) (Wolverine in the future) must be brought to the lane to breach the ditch. Both the ACE and the AVLB lack the Grizzly's survivability. If more mines are encountered beyond the ditch, additional assets are required to continue the breach. The assault force will be very vulnerable to counterattack until sufficient lanes are created to push additional combat power through the breach. In summary, breaching operations currently require a high degree of coordination, skill, and training on the part of the soldiers attempting to accomplish the mission (Figure 1).

This situation is complicated by emerging full-width, multisensor mine fuzings designed to defeat our current reduction assets. The Grizzly will more easily and rapidly defeat this threat and provide an integrated breach system.



The Solution

The Grizzly promises to greatly improve the effectiveness of our maneuver forces. Under development as a variant of the proven M1 Abrams main battle tank, the Grizzly takes advantage of the M1's mobility and survivability features. With these capabilities, it can maintain the operating tempo of the Bradley- and Abrams-equipped Force XXI combined arms battalions. The Grizzly's integrated system has the capability to reduce all parts of typical obstacles (mines, wire, ditches, rubble, and log obstacles), providing responsive support to the force. The Grizzly incorporates both countermine and counterobstacle capabilities into a single survivable system that, in one pass, creates a lane trafficable by the entire maneuver force. Figure 2 compares the breach capability of current equipment with the Grizzly. Only the Grizzly is effective across the full spectrum of the threat.


Contrast the previous situation with the same breach conducted by a Grizzly-equipped force. The Grizzly is capable of breaching wire, mines, and ditches; thus, battle drills for the breach are possible. Battle drills eliminate the orchestration of obstacle reduction and ease the battle command challenge. The task force commander can concentrate on suppressing, obscuring, and securing the breach site, leaving obstacle reduction to the engineer and his Grizzly. A Grizzly crew of two can complete a breach that currently requires numerous soldiers in less survivable systems, and the Grizzly allows tanks to fight rather than breach. Perhaps most importantly, the additional tempo provided by the Grizzly allows the assault force to pass combat power sooner than is possible today.

The presence of a rapidly employed, complex obstacle system may be decisive in a battle if it permits adversaries to slow the tempo of our forces. Employing the Grizzly with maneuver task forces allows them to rapidly react to aerial- or artillery-delivered scatterable mines, point obstacles at chokepoints, mechanically emplaced mines, or a combination of these. The Grizzly enables friendly forces to dominate maneuver and strike before the enemy can effectively react. Figure 3 illustrates some of the differences the Grizzly can make to the maneuver force during a breaching operation.


Key Features

Key to the Grizzly's success is an automatic depth-control system that enables the blade to move at a consistent depth regardless of terrain conditions. This system detects changes in terrain contours and automatically directs hydraulic controllers to adjust blade height, pitch, and roll (angle). Unlike a bulldozer, which provides a final planar surface regardless of the ground contour, the Grizzly blade maintains a constant plow depth while following an undulating surface. The primary system consists of tactile sensor units, which "feel" the surface of the ground. A backup depth-control system is provided by a series of strain gages that measure shear forces on the blade and adjust the depth to maintain a constant force. Manual controls in the crew station provide additional redundancy for depth control. Research continues on sensing technologies for future product improvements.

The mine blade provides a tremendous improvement over the existing mine plow. It is designed to survive mine blasts and retract for road travel while not significantly degrading the mobility of the M1 chassis. The blade incorporates a series of tines (see photo above) that uplift mines onto the dirt spoil moving in front of the blade. The mines are then rolled to the side and deposited with soil astride the cleared lane as the vehicle moves forward. Blade action helps preclude detonation of pressure-fused mines. The Grizzly blade is also effective against the full spectrum of the the mine threat. Perhaps most importantly, the Grizzly clears the full width of the lane, in contrast to the track-width clearance available today.

A power-driven arm (Figure 4) on the Grizzly is adapted from commercial construction equipment. It provides lifting, grappling, and dirt-moving capabilities to breaches. Working together, the arm and the blade enable the crew to reduce tank ditches and log cribs and move rubble.

The Grizzly is designed for under-armor operations, which require external cameras to permit day, night, and all-weather operations. In addition, the Grizzly will be fully integrated into the Force XXI digital information system using the Force XXI Battle Command, Brigade and Below (FBCB2) software. The Grizzly will be the first drive-by-wire (computer-controlled) vehicle in the Army inventory.


Program Status

United Defense Limited Partnership is under contract to mature existing prototype vehicles for gov-ernment evaluation and testing before the low-rate initial production decision, which is scheduled for the spring of FY 2000. Testing will include operational tests with soldiers, technical testing, and live-fire tests (including mine-blast tests). A total buy of 366 vehicles is planned, with fielding to heavy division and corps (mechanized) engineer battalions scheduled to begin in FY 2004.


The Force XXI Army promises to possess an information advantage over our adversaries. Effective mobility support is essential to exploit this advantage. The Grizzly provides a revolutionary capability to the force--the ability to defeat complex obstacles while maintaining the pace and momentum of the attack. The Grizzly is essential for our Army to meet the Force XXI objectives to dominate maneuver and win the information war.


Lieutenant Colonel Kotchman, an ordnance officer with more than 18 years of service, is product manager for the Grizzly program at the Detroit Arsenal, Warren, Michigan. He is a graduate of the U.S. Military Academy and holds a master's degree from Rensselaer Polytechnic Institute, Troy, New York.

Mr. Glasgow is a military equipment analyst and technical writer with Camber Corporation, in Warren, Michigan. A former U.S. Army officer, he trained as a research, development, and acquisition specialist with assignments as an operational tester at Fort Sill and materiel developer at the U.S. Army Tank-Automotive and Armaments Command, Warren, Michigan.

Lieutenant Colonel Greene is Division Chief, TRADOC Systems Manager, Engineer Combat Systems, U.S. Army Engineer School, Fort Leonard Wood, Missouri. He is an engineer officer in the Army Acquisition Corps and a registered professional engineer. LTC Greene holds a doctorate from the University of Southern California.