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FCS And The Sherman Dilemma


Beware the “Sherman dilemma,” military historian and RAND analyst David Johnson warned the Army’s FCS program. In World War II, the U.S. War Department said tanks must not exceed 30 tons, because any heavier and it would be too hard to ship them to Europe and they would be too heavy to cross the Army’s pontoon bridges. The result was the U.S. Army went to war with the M4 Sherman, a tank “clearly outclassed by the German heavy armor and antitank weapons it confronted… and, U.S. soldiers paid a heavier price than they should have,” Johnson writes in a study he did for the Army on the history of medium armored forces.

The Army's FCS program ran into its own “Sherman dilemma.” The service originally wanted a new class of armored vehicles transportable by C-130, so they could be rapidly flown to crisis zones, which meant they couldn’t weigh much more than 20 tons. That C-130 requirement became FCS’s “pontoon bridge,” Johnson told me. The weight constraints severely limited the amount of heavy steel armor the vehicles could be designed to carry, in addition to the engine, weapons and running gear. But FCS designers didn't adequately account for what the vehicle was supposed to do once it reached the battlefield.

The fighting in Iraq and Afghanistan has revealed the vulnerability of lightly armored vehicles to simple and often crude, yet readily available and highly lethal weapons such as the IED and RPG. In response, FCS builders added more armor and the vehicle’s weight climbed, but the original design constraints limited how much they could add.

It was the lightweight FCS vehicle’s vulnerability to anti-armor weapons that compelled Defense Secretary Robert Gates to cut the bulk of the program this week. “The program that was designed nine years ago had not really adequately integrated the lessons learned in Afghanistan and Iraq,” Gates told reporters this week, particularly, “the vulnerability of lighter armor to Explosively Formed Penetrators and IEDs.” FCS also failed to account for “operational realities,” including the value of heavy armor in low-intensity fights where lethality is very high because of readily available anti-armor weaponry.

FCS vehicles had a flat bottom, a design flaw that proved lethal to Humvees in Iraq hit by IEDs because it creates a gas trap that focuses the blast, said Vice Chairman of the Joint Chiefs of Staff Gen. James Cartwright. As FCS designers kept adding armor it became questionable whether the vehicle’s axles and transmission could handle more weight. In the end, the Army was trying to cram the mobility of an 18-ton wheeled Stryker and the survivability of a 70-ton Abrams tank into the same vehicle, and it just wasn’t going to happen, Cartwright said.

"At the low end, you're trying to be offensive and move through an area very quickly through any kind of terrain. At the very high end, you're moving slowly, you're probing, you're accepting the fact that you're going to take on heavy fire and that you're going to have to withstand it... a single vehicle to do this is really questionable," Cartwright said.

Pentagon sources told me that once the FCS program’s progress on developing an active protection system -- a complex defensive suite designed to shoot down incoming projectiles -- ran into technological roadblocks, the FCS vehicles were doomed. The Army has long said active protection would give the FCS vehicles survivability approaching that of the 70-ton Abrams main battle tank. Former FCS program manager Army Maj. Gen. Charles Cartwright once said active protection would be one of the program’s early “spin outs” to the current battle fleet.

But the FCS active protection system has suffered serious technological challenges, as GAO auditors recently discovered. The whole effort has been classified and active protection was dropped from the list of potential FCS spin outs. Sources told me the FCS program could not successfully pull off a mobile firing test of the system. So then it came back to the issue of how much armor they could hang on the vehicles, and at less than 30 tons they just did not have enough.

The Army thought they could substitute information for heavy armor. That technology would pierce the fog of war and they could see the enemy clearly on the battlefield. That was a fantasy. Retired Army Gen. Bob Scales once told me that the FCS "bubble of information as protection" idea worked when you're talking about a wide open battlefield. But once you get into close combat in urban areas, where engagement ranges are often measured in a few feet, the whole concept breaks down. As Gates told reporters, he was troubled by the "reliance on the situational awareness... traded off against armor" given the battlefield experiences from Iraq and Afghanistan.

“When you’re inside a real city, where you can’t see the guy with the RPG who’s hiding in an interior room, and there are 20 of them out there hiding with RPGs, you have real problems if you can’t survive RPGs,” Johnson told me. “You must have sufficient armor protection to at least stop RPGs.” The FCS vehicles did not. Nor were they protected through design against IEDs. To survive on future battlefields, combat vehicles, at a minimum, must be protected against the most common threats.

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