Ever since the first primitive tanks appeared on the Western Front a hundred years ago, it has been the firm conviction of armored-warfare experts that tracked vehicles equipped with treads were better suited to mobility in mud and sand than wheeled vehicles. As a result, all of the major combat vehicles bought by the U.S. military during the Cold War — the tanks, the troop carriers, the self-propelled howitzers, the amphibious vehicles — were tracked systems. But a combination of new threats, new technology and fiscal realities is now leading military planners to rethink the conventional wisdom.
The change in thinking began when the Army fielded an eight-wheel “interim armored vehicle” after 9-11 called the Stryker that was designed to be more flexible and deployable than traditional tracked vehicles. With wars raging in Iraq and Afghanistan, the Army learned quickly how to equip and use the Stryker to achieve tactical objectives while affording maximum protection to occupants. The vehicle, which is produced in multiple variants based on a common chassis, now looks likely to remain in the Army’s active inventory through mid-century. Meanwhile, the Marine Corps has abandoned plans to buy a new tracked amphibious assault vehicle, and is seeking wheeled solutions that can accomplish ship-to-shore maneuvers.
Marine planners say wheeled technology is good enough, given limits on available funding. Of course, one reason they can say that is that the new vehicle will be teamed with the existing Assault Amphibious Vehicle — a tracked system. But the fact the Marines are willing to consider a wheeled vehicle for use in the unforgiving environment of amphibious warfare suggests that they have reassessed what wheeled-vehicle technology can deliver. That shouldn’t come as a big surprise: repeated efforts by the Army and Marine Corps to develop next-generation tracked combat vehicles have faltered, while wheeled technology has advanced steadily by adapting dual-use innovations from the commercial world.
Four types of improvement stand out. First, suspension systems designed to carry more weight have been developed that enhance the mobility, availability and stability of wheeled combat vehicles while allowing them to keep up with tracked systems in most terrain. Second, more powerful, fuel-efficient engines have greatly improved the ability of wheeled vehicles to operate in soft soil such as mud. Third, new drivetrains have been developed carrying power from engines to wheels that increase speed, reduce maintenance, bolster stability and can be readily adapted to diverse climate or terrain conditions. Finally, survivability upgrades have been introduced such as the “double-V hull” on the Stryker that give wheeled vehicles better protection against improvised explosive devices — in fact, better underside protection than most tracked systems offer.
So does all this innovation signal that wheeled combat vehicles can now deliver the same mobility as tracked systems in deep mud or sand dunes? Nope — not yet. But they are closing the performance gap, and the cost of operating wheeled vehicles is much lower than the cost of using tracks. If combat vehicles were routinely operating in knee-high mud, then users would simply have to live with the higher cost of tracks. But with most combat scenarios involving less demanding terrain, it’s a judgment call as what kind of cost burden the services should be willing to bear so they are ready for every eventuality. As military acquisition practices increasingly shift to a commercially-driven, dual-use model, wheeled options for combat missions are likely to look increasingly attractive.
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