QUANTICO, Va. — General Dynamics [GD] was able to look within its existing portfolio for a base vehicle that could be tweaked to meet the Marine Corps requirement for an off-the-shelf amphibious personnel vehicle.
It settled on evolving the Stryker 8×8 combat vehicle for use at sea as well as on land and offered the resulting vehicle for the Marines’ personnel carrier trials, which is now serving as the basis for the amphibious combat vehicle (ACV) 1.1 program.
“To some extent, yes, it is an evolution of the Stryker, but really been designed for the Marines and for the land and the sea,” Scott Stilson, GD’s ACV program manager, told Defense Daily at the Modern Day Marine technology expo at Quantico, Va. “there’s a lot of evolutionary technology in it, but it has been specifically designed for the Marines and their missions.”
GD’s ACV can be built in the existing facilities that have built over 10,000 Stryker family vehicles, many of which have seen extensive combat in Iraq, Afghanistan and elsewhere, Stilson said. The company’s ACV offering incorporates the proprietary double-V hull design that all Strykers are now fitted with to greatly increase troop protection against improvised explosive devices.
Placed nose to nose with competing vehicles from Lockheed Martin [LMT], BAE Systems and SAIC [SAIC], GD’s ACV has a noticeably stubbier bow, which give the driver and commander greater field of vision, Stilson said. The abbreviated length of the vehicle also provides buoyancy.
A Caterpillar [CAT] engine can propel the vehicle faster than 6 knots through the water, a fairly standard speed for the major competitors. The vehicle displayed at Modern Day Marine was configured to carry 12 Marines plus three crew members.
The Marine Corps originally–and may yet–wanted a tracked vehicle because they have greater mobility in sand than wheeled vehicles. Each company has developed unique drive-train architectures to allow the wheels to be operated independently or locked together, providing the attributes of both wheels and tracks. GD’s vehicle has the ability to lock pairs of tires together on either side so when one lifts or dips, the other moves the opposite direction, keeping constant contact with the ground.
“We tried to keep everything very simple for the Marine to maintain it and to operate it,” Stilson said.
In the interest of simplicity, GD designed a mechanical drive train and water propulsion system. Other candidates have incorporated an independent hydraulic in-water propulsion system, which Stilson said increases the complexity and decreases reliability of the system. The same controls are used during both land and sea modes. Using a shifter much like in a manual car, the driver simply switches differentials that apply engine power to either the wheels or to the props, Stilson said.
“It’s more efficient in transferring power back to the propulsion system,” he said. “We don’t have losses in hydraulic pumps or motors. From a maintenance point of view, hydraulics leak, you need new fittings, passthroughs in the hull and more parts.”
The vehicle also has a height-management system that allows it to lower onto its suspension for stowage aboard ship or to drive under an overhead obstacle and to increase its ground clearance to drive over obstacles. Raising the hull away from the ground also increases survivability in case of an underbelly blast.
GD designed in reserve buoyancy, payload capacity and excess power generation to support anticipated requirements for an ACV 1.2, which is expected to introduce turreted and command variants, higher water speed and the ability to launch and recover from the well deck of an amphibious assault ship. Both the hull and suspension were designed to structurally accept the weight of a 30mm gun turret, which is a requirement expected in ACV 1.2.
“We tried to look forward and integrate those things into the core system and components–the drive line, the suspension, the power pack–so that they can grow the vehicle and keep it around for the next 20, 30 years.”