Wheels vs. Tracks Redux

In the Army’s quest to develop a new armored combat vehicle in the wake of the fiasco that was the FCS program, Army Chief Gen. George Casey has vowed to start with a “clean sheet of paper.” He even went so far as to say the Army was considering a wheeled vehicle, as the basis for a future armored fleet. I asked Casey whether the Army really wanted to revisit the wheeled versus tracks debate from the early days of FCS and he assured me it was a serious option.

It seems every time the Army discusses developing a new armored vehicle the same question arises: which is better, wheeled versus tracks? There are clear advantages and disadvantages with each.

An argument can be made that with the rapid urbanization of the planet’s surface, the much greater mobility of wheeled vehicles on paved roads, and the fact that they’re much kinder to those roads, means wheels makes tremendous sense. As troop carriers, wheels offer a far gentler ride than tracks. And as monster truck fans know, wheeled drive trains and axles allow the chassis to be raised far above the ground, important on current and future IED strewn battlefields.

The problem with wheeled vehicles is they fast reach an upper weight limit, around the 30 ton range, where performance goes completely out the window; wheels just offer far less footprint to spread the weight around than tracks. As designers start adding heavier armor packages and bigger guns, tracks become the only option. Some European companies build wheeled big howitzers, but their off-road performance is really poor (western European combat vehicle procurement over the past decade has shifted away from tracks to medium weight wheeled vehicles). With its various bolt-on armor and electronics packages, the Army’s Stryker has run into weight related performance problems, Army vice chief Gen. Peter Chiarelli said recently.

Once off-road and in soft ground or deep sand, wheeled vehicles get into real trouble; tracks provide much greater off-road mobility, whether in Bosnian mud and snow or the soft sands of Iraq’s western desert. Also, the mud brick wall crushing ability of tracks often comes in handy, as the Canadians discovered (as the Russians did before them) when fighting the Taliban in the “green belts” of southern Afghanistan where farm fields are divided by thick walls. The Canadians airlifted Leopard tanks to provide troops there armored, mobile direct fire support; the tank’s big guns proved very useful in blowing “mouse holes” in walls and buildings, allowing troops to move through rather than around structures. As the U.S. military learned in Baghdad, the 70 ton Abrams is a most effective mobile pillbox.

The first question the Army must answer is whether they want their future combat vehicle to be a replacement for the Abrams tank or a lighweight, rapidly deployable vehicle, because the requirements for the two are very different. That the service has convened a “Ground Combat Vehicle Blue Ribbon Panel,” inviting input from a range of experts to help them craft vehicle requirements, shows they haven’t yet made up their mind on what exactly they want in a new vehicle.

When former Army chief Gen. Eric Shinseki first pitched FCS back in 1999, he envisioned lightweight vehicles that would permit deployment of a full brigade anywhere within 96 hours; the Stryker brigades were also part of the Army’s new “expeditionary” theme (A former Shinseki aide, now a high ranking general, told me about the behind-the-scenes anti-Stryker campaign the Marines ran in Congress in an effort to prevent the Army from impinging on their expeditionary turf). Army planners said the new FCS vehicles would be much lighter than an M-1 Abrams, although just as lethal and survivable.

It’s that last bit that proved FCS’ undoing, said armored vehicle historian Steven Zaloga, when I spoke to him recently about the Army’s combat vehicle efforts. Active protection systems - adorning tanks with defensive radars and projectiles to shoot down incoming rounds - were not technologically advanced enough to supplant thick armor. Improved situational awareness is not an adequate substitute either. Iraq and Afghanistan showed the vulnerability of lightly armored vehicles to readily available anti-armor weapons in irregular wars. As Chiarelli told lawmakers, while transportability might be an important feature for planners, for troops in the field, survivability trumps all.

When the Army designed the Abrams, its most successful tank program ever, it knew exactly what it wanted: a heavily armored, large gunned, low slung, Soviet tank killer, Zaloga said. The vehicle portion of FCS never really got off the ground because the Army wasn’t sure what it wanted in a new vehicle. It also got too hung up on building common vehicles with shared parts to cut down on logistics. Combat vehicles should be based on the tactical requirements of combat, not trimming the logistics tail.

Historically, the Army has had trouble developing a forced entry vehicle because it always wants to give it a tank killing ability, Zaloga said, which means a big gun, which immediately creates problems with recoil and weight (see Stryker Mobile Gun System). Yet, as he points out, typical rapid entry scenarios don’t envision tank-versus-tank engagements. If it wants a rapid entry vehicle, the Army would be better off putting a short barreled howitzer or a rapid fire cannon on a lightweight vehicle and relying on anti-armor missiles to kill tanks.

In his excellent study of medium armored forces, In the Middle of the Fight, (a must read for all those blue ribbon panel members), RAND’s David Johnson writes that medium weight vehicles have proven particularly valuable in contingencies at the lower end of the conflict scale by providing protected mobility, mobile firepower and rapid reaction that light troops lack. The rescue of Army Rangers and Delta in Mogadishu in 1993 by an armored column is a good example.

As the Army designs its future combat vehicle(s) it must answer the question of whether it wants an expeditionary force vehicle or something that can slug it out with the Russian built T-series tanks sitting in most developing world depots. Since its rebuilding thousands of Abrams tanks, it appears those monsters will be around for a while, and they do fit on a C17. The proliferation of lethal anti-armor weapons on hybrid battlefields will put the stress on survivability, which means heavier armor, even if the Army wants a more deployable vehicle.